U.S. patent application number 10/121234 was filed with the patent office on 2002-09-26 for method of controlling a torque transmission system and torque transmission system for carrying out the method of controlling.
This patent application is currently assigned to LuK Getriebe System GmbH. Invention is credited to Muller, Bruno, Rauser, Martin, Reuschel, Michael, Salecker, Michael, Wagner, Alfons, Wagner, Uwe.
Application Number | 20020134637 10/121234 |
Document ID | / |
Family ID | 27435921 |
Filed Date | 2002-09-26 |
United States Patent
Application |
20020134637 |
Kind Code |
A1 |
Salecker, Michael ; et
al. |
September 26, 2002 |
Method of controlling a torque transmission system and torque
transmission system for carrying out the method of controlling
Abstract
A method of monitoring a torque transmission system with a
manually switchable gearbox in the power train of a motor vehicle
involves the utilization of at least one sensor unit at the input
side of the torque transmission system to ascertain relevant
positions of the shift lever of the gearbox and the driving torque
of the engine of the motor vehicle. The thus obtained shift lever
signals are memorized, together with comparison signals which are
obtained as a result of filtering of the shift lever signals, and
various characteristics of such signals are recognized and
identified to indicate the intention of the operator of the vehicle
regarding the switching of the gearbox. The thus obtained switching
intention signals are transmitted to a controlled clutch operating
system.
Inventors: |
Salecker, Michael; (Achern,
DE) ; Wagner, Uwe; (Buhl-Weitenung, DE) ;
Reuschel, Michael; (Buhl, DE) ; Rauser, Martin;
(Buhl-Balzhofen, DE) ; Muller, Bruno; (Buhlertal,
DE) ; Wagner, Alfons; (Buhl, DE) |
Correspondence
Address: |
DARBY & DARBY P.C.
Post Office Box 5257
New York
NY
10150-5257
US
|
Assignee: |
LuK Getriebe System GmbH
|
Family ID: |
27435921 |
Appl. No.: |
10/121234 |
Filed: |
April 12, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10121234 |
Apr 12, 2002 |
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09563094 |
May 2, 2000 |
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6386351 |
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09563094 |
May 2, 2000 |
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09227003 |
Jan 7, 1999 |
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6105743 |
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09227003 |
Jan 7, 1999 |
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08788011 |
Jan 21, 1997 |
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5890992 |
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08788011 |
Jan 21, 1997 |
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08393316 |
Feb 22, 1995 |
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5679091 |
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Current U.S.
Class: |
192/54.1 ;
477/86 |
Current CPC
Class: |
B60W 10/04 20130101;
B60W 2510/0241 20130101; F16H 45/02 20130101; B60W 2510/0638
20130101; B60W 2540/12 20130101; F16D 2500/308 20130101; F16H
59/044 20130101; F16D 2500/3056 20130101; F16D 2500/70626 20130101;
F16H 59/14 20130101; F16H 63/46 20130101; F16D 2500/70434 20130101;
B60W 30/18 20130101; F16H 2061/145 20130101; B60W 2510/0671
20130101; F16D 2500/1024 20130101; F16H 61/143 20130101; F16D
48/064 20130101; F16D 2500/1085 20130101; B60W 2050/0031 20130101;
F16H 61/66 20130101; B60W 2710/027 20130101; F16H 59/0217 20130101;
F16D 2500/7041 20130101; B60K 28/165 20130101; F16D 2500/3144
20130101; F16H 59/36 20130101; B60W 2510/0623 20130101; F16D
2500/70217 20130101; F16H 61/12 20130101; B60W 2050/0011 20130101;
B60W 2050/021 20130101; B60W 2050/0052 20130101; F16D 48/06
20130101; F16D 2500/306 20130101; Y02T 10/40 20130101; B60W 30/20
20130101; F16H 61/662 20130101; F16D 2500/70615 20130101; B60W
10/101 20130101; B60W 2050/0042 20130101; B60W 2510/0657 20130101;
B60W 2710/025 20130101; F16D 2500/3161 20130101; F16H 61/664
20130101; F16H 2059/385 20130101; F16H 2061/0087 20130101; F16D
48/066 20130101; F16D 48/068 20130101; F16D 2500/70426 20130101;
B60W 2710/105 20130101; F16H 2061/0015 20130101; F16D 2500/7044
20130101 |
Class at
Publication: |
192/54.1 ;
477/86 |
International
Class: |
F16D 043/20 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 23, 1994 |
DE |
P 44 05 719.9 |
May 26, 1994 |
DE |
P 44 18 273.2 |
Jul 21, 1994 |
DE |
P 44 25 932.8 |
Oct 24, 1994 |
DE |
P 44 37 943.9 |
Claims
We claim:
1. A torque transmission system for transmitting torque from an
input side to an output side of a drive train of a motor vehicle
having an engine and a cone pulley gearbox, the torque transmission
system comprising: at least one component adapted to transmit
torque, wherein the torque transmission system is controlled in
such a way that the torque which can be transmitted by the torque
transmission system is always less than the torque which can be
transmitted by the cone pulley gearbox.
2. The torque transmission system according to claim 1, wherein the
cone pulley gearbox comprises: a variator assembled of two pairs of
cone pulley sets; an endless torque transmitting device; and a
control system, which regulates the contact pressure of the endless
torque transmitting device between the pairs of cone pulley
sets.
3. The torque transmission system according to claim 1, wherein the
at least one component comprises at least one clutch a torque-flow
path before or after the cone pulley gearbox.
4. The torque transmission system according to claim 1, wherein the
torque transmission is controlled to prevent rotary oscillations
originating from the engine and causing an excessive contact
pressure to be exerted on the endless drive.
5. The torque transmission system according to claim 2, wherein the
torque transmission system is controlled to protect the variator
from torque surges at the output side.
6. The torque transmission system according to claim 1, wherein the
at least one component comprises a discrete safety clutch.
7. The torque transmission system according to claim 1, wherein the
at least one component comprises a lockup clutch of a torque
converter.
8. The torque transmission system according to claim 1, wherein the
at least one component comprises a clutch of a turning set.
9. The torque transmission system according to claim 2, wherein
said torque transmission system has an additional clutch for
adjusting the variator.
10. A torque transmission system for transmitting torque from an
input side to an output side of a drive train of a motor vehicle
having an engine and a cone pulley gearbox, the torque transmission
system comprising: at least one clutch for transmitting torque,
wherein the at least one clutch is controlled in such a way that
the torque which can be transmitted by the torque transmission
system is always less than the torque which can be transmitted by
the cone pulley gearbox.
11. The torque transmission system according to claim 10, wherein
the cone pulley gearbox comprises: a variator assembled of two
pairs of cone pulley sets; an endless torque transmitting device;
and a control system, which regulates the contact pressure of the
endless torque transmitting device between the pairs of cone pulley
sets.
12. The torque transmission system according to claim 10, wherein
the at least one clutch is selected from the group consisting of a
discrete safety clutch; a lockup clutch of a torque converter, and
a clutch of a turning set.
13. The torque transmission system according to claim 10, wherein
said torque transmission system includes an additional clutch for
adjusting the variator.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This patent application is a divisional of U.S. patent
application Ser. No. 09/563,094, filed on May 2, 2000, which is a
continuation of U.S. patent application Ser. No. 09/227,003, filed
on Jan. 7, 1999, which is a divisional of patent application Ser.
No. 08/788,011, filed Jan. 21, 1997, now U.S. Pat. No. 5,890,992
which is a continuation of patent application Ser. No. 08/393,316,
filed Feb. 22, 1995, now U.S. Pat. No. 5,679,091, all of which are
incorporated by reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] The invention relates to a method of controlling a torque
transmission system, to a torque transmission system for carrying
out the method of controlling, and to a method of monitoring torque
transmission systems.
[0003] It is known from the vehicle industry that, when changing
the transmission ratio of a gear between a driving machine and a
gearbox unit, the required clutching processes can be assisted or
automated by a control or regulating algorithm. This facilitates
the servicing of the engine unit or gearbox, and the clutching
operation can be carried out in an energy saving manner with
careful treatment of the materials. Furthermore, the control of a
torque transmission system which is mounted at the output side of
an automatic gearbox can be helpful, for example, in undertaking or
guaranteeing adjustment processes and protective functions in the
case of, for example, cone pulley belt contact gearboxes.
[0004] WO 94/04852 discloses a method of controlling torque
transmission systems in conjunction with an automatic gearbox. The
torque transmission system comprises a load branching out with a
torque converter which is mounted in parallel with a friction
clutch. In accordance with this method, a driving torque
transmitted by an engine unit is broken up into a hydraulic part
which is to be transmitted by the converter and a mechanical part
which is to be transmitted by the friction clutch, such as a lockup
clutch. A central computer unit determines or calculates, in
dependency upon the relevant operating condition of the system, the
torque which is to be transmitted each time by the friction clutch.
The remaining torque to be transmitted by the hydraulic torque
converter constitutes the difference between the applied torque and
the torque transmitted by the friction clutch and corresponds
directly to a slip between the input and output parts of the torque
transmission system.
[0005] Such method of controlling can be resorted to only in
conjunction with an automatic gearbox and a lockup clutch. However,
the acceptability of automatic gearboxes is only minimal in many
fields of use. Furthermore, a lockup clutch of such kind is
cost-intensive and bulky.
OBJECTS OF THE INVENTION
[0006] An object of the invention is to provide a method of
controlling which can be used practically universally, the
regulating quality of which is high, and which exhibits a clearly
improved load change behavior for torque transmission systems.
[0007] In addition, one should achieve cost advantages in
comparison with conventional torque transmission systems.
Furthermore, an object is to provide a torque transmission system
which can be utilized for the practice of such controlling
method.
SUMMARY OF THE INVENTION
[0008] The above objects are accomplished in that the clutch torque
which can be transmitted from an input side to an output side of a
torque transmission system with or without load distribution or
branching out is utilized as a control value and such control value
is calculated and/or determined in dependency upon an input or
driving torque.
[0009] This amounts to a realization of a torque matching concept.
The basic concept underlying the method of such kind resides in
controlling the setting member primarily in such a way that the
clutch torque which can be transmitted by the torque transmitting
parts is mainly just above or just below the driving torque at the
input side or drive side of the torque transmission system.
[0010] As a rule, a torque transmission system must be designed for
the transmission of two to three times the maximum driving torque
of a driving machine, such as an engine. However, the driving
torque which is typical of the operation is but a fraction of the
maximum driving torque. The torque matching renders it possible to
establish only that force-locking engagement which is required
between the torque transmitting parts in lieu of a quasi permanent
excessive overpressure.
[0011] A further advantage resides in the provision of a
controlling method. In contrast to a regulation, the feedback of
condition values of the torque transmission system is not
absolutely necessary. It serves merely for a possible enhancement
of the control but is not required in order to establish the
operation of the torque transmission system. The task of a torque
transmission system of such kind is to transmit torque. Therefore,
it is expedient to use the transmittable clutch torque as a control
value.
[0012] An advantageous embodiment of the invention is characterized
in that, in a method of controlling a torque transmission system
with or without load distribution or branching out which controls
the torque adapted to be transmitted from an input side to an
output side of the torque transmission system, the latter comprises
a sensor system for detecting the values to be measured and a
central control or computer unit which is connected with the sensor
system, the torque which can be transmitted by the torque
transmitting system being controlled in such a way that the
transmittable torque is calculated, adapted and controlled as a
function of a driving torque, and deviations from an ideal state
are compensated for long-term through corrections.
[0013] Furthermore, it can be of advantage to resort to a method
which serves to control a torque transmission system, especially
for motor vehicles, wherein the torque transmission system is
installed in the power flow downstream of a driving machine and in
the power flow upstream or downstream of a shiftable device, such
as a gearbox, and controls the torque which can be transmitted from
an input side to an output side of the torque transmission system,
and the power transmission system includes a control or computer
unit which is in signal connection with sensors and/or other
electronic units, the torque which can be transmitted by the torque
transmitting system being calculated as a function of a driving
torque and being adaptively controlled, with deviations from an
ideal condition compensated for long-term through corrections.
[0014] According to another embodiment, the control value can be
triggered by means of a setting member supplied with a setting
value which is functionally dependent upon the transmittable clutch
torque, in such a way that the transmittable clutch torque lies
within a predetermined tolerance range at a slip limit wherein this
slip limit is reached when the effect of a torque being applied at
the input side exceeds the clutch torque which can be transmitted
by the torque transmitting parts.
[0015] The method according to such embodiment can be carried out
particularly in such a way that the torque which can be transmitted
by a torque transmission system, such as a friction clutch and/or a
hydrodynamic torque converter with or without converter lockup
clutch and/or a starter clutch for automatic gearboxes and/or a
turning set clutch and/or a torque transfer system connected in
front of or behind an infinitely adjustable gearbox, such as a cone
pulley belt contact gearbox, can be controlled as a function of a
driving torque so that in the case of systems with load
distribution or load branching, such as a hydrodynamic torque
converter with converter lockup clutch, the torque which can be
transmitted by the clutch is determined in accordance with the
torque equation
M.sub.KSoll=K.sub.ME*M.sub.AN
[0016] and
M.sub.Hydro=(1-K.sub.ME)*M.sub.AN
[0017] wherein the two equations apply for K.sub.ME.ltoreq.1
and
M.sub.KSoll=K.sub.ME*M.sub.AN
[0018] and
M.sub.Hydro=0
[0019] applies for K.sub.ME>1 with
[0020] K.sub.ME torque division factor
[0021] M.sub.KSoll=desired clutch torque
[0022] M.sub.AN applied torque
[0023] M.sub.Hydro=torque transmittable by the hydrodynamic torque
converter
[0024] and a torque difference between the torque M.sub.AN applied
to the torque transmission system by the driving aggregate and the
torque M.sub.KSoll transmittable by the clutch is transmitted
through the hydrodynamic torque converter wherein a minimum slip is
established independently between the engine and the output of the
torque transmission system in dependency upon the torque division
factor K.sub.ME and deviations from the ideal condition are
adoptively detected, processed and compensated for long-term.
[0025] A further embodiment of the method according to the
invention proposes that the torque transmittable by the torque
transmission system be controlled as a function of a driving torque
so that in the case of systems without load distribution, such as a
friction clutch and/or a starting clutch and/or a turning set
clutch and/or a torque transmission system of an automatic gearbox
or an infinitely adjustable gearbox, such as a cone pulley belt
contact gearbox, the torque which can be transmitted by the
friction clutch or starting clutch
M.sub.KSoll=K.sub.ME*M.sub.AN
[0026] is ascertained and a definite overpressing of the torque
transmitting parts is carried out for K.sub.ME.gtoreq.1.
[0027] Furthermore, it can be advantageous if the torque which can
be transmitted by a torque transmission system is varied as a
function of a driving torque in such a way that in the case of
systems without load distribution, such as a friction clutch and/or
a starter clutch and/or a torque transfer system of an automatic
gearbox and/or an infinitely adjustable cone pulley belt contact
gearbox, the torque which can be transmitted by the torque
transmission system
M.sub.KSoll=K.sub.ME*M.sub.AN+M.sub.Sicher
[0028] is ascertained and for K.sub.ME<1 a fictitious load
distribution is reconstructed through a supporting control loop to
be a copy of the behavior of a parallel-connected torque
transmission system, such as a hydrodynamic torque converter, and a
proportion of the transmittable torque is transmitted through the
torque control and the remaining torque is subsequently transmitted
in dependency upon slip through a safety torque M.sub.Sicher.
[0029] Furthermore, it can be advantageous if the safety torque
M.sub.Sicher is selected in dependency upon each operating
point.
[0030] Similarly, it can be advantageous if the safety torque
M.sub.Sicher is ascertained and/or controlled in functional
dependency upon the slip .DELTA.n or the throttle valve position d
according to
M.sub.sicher=f(.DELTA.n, d).
[0031] Similarly, it can be expedient if the safety torque
M.sub.Sicher is ascertained and/or controlled in accordance
with
M.sub.Sicher=const.*.DELTA.n.
[0032] Furthermore, it can be advantageous if the torque division
factor K.sub.ME is constant within the entire operating range of
the power train.
[0033] Similarly, it can be advantageous if the torque division or
branching off factor K.sub.ME assumes an individual value which is
ascertained for each operating point and/or assumes at least in a
portion of the operating range a relevant constant value each time;
the values set in different portions of the operating range can be
different.
[0034] In this manner, it is advantageously possible to divide the
entire operating range into partial ranges wherein, in each partial
range, the K.sub.ME value is kept constant and the constant
K.sub.ME value can vary from operating range to operating
range.
[0035] Furthermore, it may be advantageous if the value of the
torque division factor K.sub.ME is in functional relationship
dependent upon the input RPM and/or the vehicle speed.
[0036] In accordance with the inventive concept, it can be
advantageous if the value of the torque division factor K.sub.ME is
dependent exclusively upon the speed of the driving aggregate.
[0037] It can be equally advantageous if the value of the torque
division factor is dependent, at least in a portion of the entire
operating range, both upon the RPM and upon the input torque of the
driving aggregate.
[0038] Furthermore, it may be advantageous if the value of the
torque division factor K.sub.ME is dependent not only upon the
output RPM but also upon the torque of the driving aggregate.
[0039] Furthermore, it can be advantageous if a certain desired
clutch torque is transmitted by the torque transmission system
substantially at each point in time. It can thereby be expedient if
the transmittable clutch torque follows the existing torque.
[0040] Such embodiment exhibits the advantage that the contact
pressure of the torque transmission system need not be maintained
permanently at the highest value. According to the teaching of
prior art, a torque transmission system (such as a clutch) is acted
upon by a multiple of the nominal engine torque.
[0041] In an automated torque transmission system, the following of
the transmittable torque entails that the setting device or actor
not only initiates the opening and closing processes during
switching and starting but that the setting device selects the
transmittable torque at each operating point to a value which
corresponds at least substantially to the desired value.
[0042] In order that the setting device or actor need not be
constantly active during follow-up, it may be expedient if the
torque which can be transmitted by the torque transmission system
is controlled with an overpressure and the overpressure lies within
a narrow scatter band in relation to the desired value.
[0043] It can be expedient if the overpressure AM is dependent upon
the operating point.
[0044] It can be particularly advantageous if the operating range
is divided into partial ranges and the contact pressure and/or the
maximum overpressure is fixed for each partial range.
[0045] In accordance with a further embodiment of the invention, it
may be advantageous if the application of the contact pressure
and/or of the overpressure and/or of the transmittable clutch
torque is variable in time.
[0046] Similarly, according to the inventive concept, it may be
advantageous if the transmittable clutch torque which is to be
selected does not drop below a minimum value M.sub.Min. The minimum
torque can depend upon the operating point and/or upon the
momentary operating range and/or upon the time.
[0047] Furthermore, the torque follow-up can be carried out by a
combination of a time-variable follow-up with a minimum value which
follow-up is specific to the operating point.
[0048] According to the inventive concept, it can be advantageous
if an operating point or the existing operating condition of a
torque transmission system and/or of a combustion engine is
ascertained on the basis of condition values determined or
calculated from measurement signals, such as in dependency upon the
engine RPM and the throttle valve angle, in dependency upon the
engine RPM and the fuel throughput, in dependency upon the engine
RPM and the inlet manifold underpressure, in dependency upon the
engine RPM and the injection time or in dependency upon the
temperature and/or friction value and/or slip and/or the load lever
and/or the load lever gradient.
[0049] In a torque transmission system with a combustion engine
mounted at the input side, it is of advantage if the input torque
of the combustion engine can be determined from at least one of the
condition values of the operating point, such as the engine RPM,
throttle valve angle, fuel throughput, inlet manifold
underpressure, injection time or temperature.
[0050] Still another embodiment of the method proposes that the
torque M.sub.AN*K.sub.ME which is applied at the input side of the
torque transmission system is influenced and/or altered with a
dependency taking into account the dynamics of the system, the
dynamics of the system being adapted to be caused by the dynamic
behavior as a result of the mass moment of inertia and/or free
angles and/or damping elements.
[0051] It can be advantageous to provide means which purposefully
restrict or influence the dynamics of the system.
[0052] Similarly, it can be advantageous if the dynamics of the
system are realized to influence M.sub.AN*K.sub.ME in a form
corresponding to that of gradient restriction.
[0053] The gradient restriction can be realized as a limitation of
a permissible increment.
[0054] Furthermore, it can be advantageous if the gradient
restriction is realized in that the time-dependent change and/or
the time-dependent increased intensity of a signal is compared with
the maximum permitted slope or slope function and, when the maximum
permissible increment is exceeded, the signal is replaced with a
substitute signal which is incremented with a previously defined
slope.
[0055] Furthermore, it can be advantageous if the influencing or
restriction of the dynamics of the system is set up according to
the principle of a timely dynamic and/or variable filter wherein
the characteristic time constants and/or amplifications are time
variable and/or dependent upon the operating point.
[0056] Advantageously, the dynamics of the system are taken into
account and/or processed with a PT.sub.1 filter.
[0057] It can likewise be advantageous if the dynamics of the
system are characterized by a maximum restriction wherein, when a
certain threshold value is exceeded, the desired value is
represented by the threshold value and, consequently, the desired
value does not exceed a maximum value which is represented by the
threshold value.
[0058] Furthermore, it can be advantageous to connect in series at
least two means for controlling the system, such as a gradient
restriction and a filter stage.
[0059] It can likewise be advantageous to connect in parallel at
least two means for influencing the dynamics of the system, such as
a gradient restriction and a filter.
[0060] It is particularly advantageous if the dynamics of the
combustion engine and the dynamics of the secondary consumers which
cause a load distribution are taken into account when determining
the driving torque M.sub.AN. In such instances, it is especially
advantageous if the mass moments of inertia of the utilized
flywheel masses and/or elements are resorted to in order to take
into account the dynamics of the combustion engine.
[0061] It can likewise be advantageous if the injection behavior of
the combustion engine is relied upon and/or forms the basis for the
consideration of the dynamics of the combustion engine.
[0062] It is likewise within the scope of the controlling method
according to the invention to compensate for deviations from the
ideal state long-term by taking into consideration the secondary
consumers and/or the correction and/or the compensation for
disturbances and/or sources of disturbances.
[0063] It can be advantageous if the torque being applied at the
input side of the torque transmission system is detected and/or
calculated as a difference between the engine torque M.sub.mot and
the sum of the torques taken up or branched off by the secondary
consumers. For example, the secondary consumers to be considered
can include the climate control and/or the dynamo and/or the servo
pumps and/or the steering aid pumps.
[0064] According to the inventive concept, it can be advantageous
if system condition values, such as the engine RPM and the throttle
valve angle, the engine RPM and the fuel throughput, the engine RPM
and the inlet manifold underpressure, the engine RPM and the
injection time, the engine RPM and the load lever are used to
determine the value of the engine torque M.sub.mot.
[0065] Furthermore, it can be advantageous if system condition
values are relied upon to ascertain the engine torque M.sub.mot
from a characteristic field of the engine. Analogously, it can be
advantageous if system condition values are used to determine the
engine torque M.sub.mot and the engine torque is determined through
the solution of at least one equation or an equation system. The
solution of the equation or the equation system can be carried out
numerically and/or can be ascertained from the characteristic field
data.
[0066] Furthermore, it can be advantageous if the torque takeup
resp. the load distribution of the secondary consumers is
determined from measured values, such as voltage and/or current
measured values of the dynamo and/or switch-on signals of the
relevant secondary consumers and/or other signals indicating the
operating condition of the secondary consumers.
[0067] Furthermore, it can be advantageous if the torque takeup of
the secondary consumers is determined by means of measured values
from the characteristic fields of the relevant secondary consumers.
Likewise, the torque takeup of the secondary consumers can be
determined by solving at least one equation or an equation
system.
[0068] According to the inventive concept, it can be expedient if
the corrected transmittable clutch torque can be determined
according to the torque equation
M.sub.KSoll=K.sub.ME(M.sub.AN-M.sub.Korr)+M.sub.Sicher
[0069] and the correction torque M.sub.Korr is obtained from a
correction value which is dependent upon the sum of torques taken
up or branched off by the secondary aggregates.
[0070] Furthermore, it can be advantageous if a correction is
carried out for disturbances or breakdowns which influence
measurable system input values.
[0071] It can be particularly advantageous for the novel method if
measurable disturbance factors are detected and/or identified and
are at least partially compensated for and/or corrected through a
parameter adaption and/or a system adaption. Furthermore, it can be
advantageous if one utilizes measurable system input values in
order to identify disturbance or breakdown values and/or to correct
and/or to compensate at least partially for such values through
parameter adaption and/or system adaption.
[0072] In order to identify a disturbance value and/or to correct
the same by means of a parameter adaption and/or system adaption
and/or to compensate for the same, at least in part, it is possible
to use as parameters certain system input values such as for
example temperatures, RPM, friction value and/or slip.
[0073] It can be particularly advantageous for the method if a
compensation and/or correction of measurable disturbance factors is
carried out through adaption of the characteristic field of the
engine.
[0074] In such instances, it may very well be the case that one
observes or registers a disturbance or breakdown value which need
not be causally connected with the characteristic field of the
engine but a correction of such disturbance value through an
adaption of the characteristic field of the engine can be
advantageous. In such instance, the cause of the disturbance is not
corrected or compensated for.
[0075] Furthermore, it can be of advantage if a correction field of
characteristic lines is established on the basis of a comparison
between the desired clutch torque and the actual clutch torque, and
a correction value is or can be ascertained for each operating
point; such correction value is linked, additively and/or
multiplicatively, with the value of the engine torque from the
characteristic field of the engine.
[0076] Furthermore, it can be particularly expedient if, in view of
a deviation detected at an operating point between the desired
value and the actual value, analyses and/or undertakings are
introduced in order to calculate and/or establish deviations and/or
correction values at other operating points of the entire operating
range.
[0077] Furthermore, it can be advantageous if, in the light of a
deviation detected at an operating point, one introduces analyses
and/or measures in order to calculate or establish deviations
and/or correction values at other operating points of a limited
operating range. As concerns the method, it can be of advantage if
the limited operating ranges are set up in dependency upon the
characteristic field.
[0078] Advantageously, an embodiment of the invention can be
characterized in that the analyses and/or undertakings for the
determination and/or calculation of deviations and correction
values at the additional operating points take into account the
entire operating range or a restricted operating range.
[0079] Furthermore, it can be advantageous if the analyses and/or
undertakings for the calculation of deviations and/or correction
values at the further operating points embrace only partial areas
around the actual operating point. It can be particularly
advantageous if the analyses and/or undertakings for the
determination and/or calculation of deviations and/or correction
values are carried out at the further operating points in such a
way that weighting factors evaluate or emphasize different portions
of the entire operating range in different ways.
[0080] It can be advantageous if the weighting factors are selected
and/or calculated as a function of the operating point. It can
likewise be advantageous if the weighting factors can depend upon
the type of the disturbance or breakdown value and/or upon the
cause of the breakdown.
[0081] Furthermore, it can be particularly advantageous if, upon
completed determination of the correction value and/or subsequent
to weighting of the characteristic correction field, a time
behavior is impressed upon the correction value. For example, such
time behavior may take into account the dynamic behavior of the
system.
[0082] It can be advantageous if the time behavior is determined
through a pulse frequency, a scanning of the correction value
and/or if the time behavior is determined by at least one digital
and/or analog filter.
[0083] It can be particularly advantageous in an embodiment of the
invention if the time behavior is varied for different breakdown
values and/or different breakdown sources, namely in the event of
using a relevant filter the parameters of the filter are set in
dependency upon the nature and the manner of action of the
breakdown source. Thus, the time constants and amplifications of
the filters conform to the respective breakdown sources in order to
guarantee an at least substantially optimal adaption.
[0084] It can be advantageous if the time behavior is selected in
dependency upon the value of the corrections. It can be
particularly advantageous if the driving torque is adapted with an
adaption method with greater or smaller time constant than the time
constant of the adaption method of the clutch torque. It is
advantageous if the time constant is within a range of between 1
second and 500 seconds, but preferably within a range of between 10
seconds and 60 seconds and most preferably within a range of
between 20 seconds and 40 seconds.
[0085] In accordance with a further embodiment, it can be expedient
if the time constant is dependent upon the operating point and/or
if the time constant is selected and/or ascertained differently for
different operating ranges. Furthermore, it can be of advantage if
a compensation for and/or correction of measurable breakdown values
is carried out through adaption of the inverse transfer function of
the transmission unit with setting member.
[0086] A further advantageous embodiment of the method provides
that indirectly measurable breakdown values, such as especially the
aging and/or straying of individual component parts of the torque
transmission system are detected in that some characteristic values
of the torque transmission system are monitored and the actually
disturbed parameters are detected and corrected in dependency upon
such monitoring and/or virtual breakdown sources can be put to use
in the form of program modules in order to correct and/or
compensate for the influence of the breakdown values.
[0087] Furthermore, it can be advantageous if disturbances from
non-measurable influence values, the straying of individual
component parts and/or the aging are detected and/or compensated
for through deviations from condition values of the system.
Furthermore, it can be advantageous if disturbances or breakdowns,
such as straying or aging or other non-measurable influence values,
are not detected from measurable input values but are recognized
only by observing reactions of the system.
[0088] It can likewise be advantageous if the deviations from
system condition values or condition values and/or observations of
system reactions are measured directly and/or calculated from other
measured values in a method model. It can likewise be advantageous
to carry out the detection of deviations from calculated method
models by resorting to characteristic reference fields and/or
unequivocal characteristic reference values of the system.
[0089] Another advantageous further development of the invention
provides that, for the correction and/or for the compensation of a
detected disturbance or breakdown from non-measurable input values
a breakdown source be localized and/or a breakdown source be fixed
and the deviations at these breakdown sources be corrected and/or
compensated for. Furthermore, it can be expedient if, for the
correction of and/or for the compensation for a detected breakdown,
one fixes a fictional breakdown source which need not have a causal
connection with the breakdown and at which the detected deviation
is corrected.
[0090] Advantageously, the fixed breakdown source can be an
actually existing function block and/or the fixed breakdown source
can constitute a virtual breakdown model whilst preserving the
correcting action.
[0091] According to a further development of the invention, the
timely progress of the actual clutch torque is monitored and
analyzed to ascertain whether conclusions regarding the type of
error and/or the detection of the breakdown source and/or the
localization of the breakdown source can be arrived at.
[0092] Furthermore, it can be advantageous to permanently carry out
the adaptive correction of the breakdown value.
[0093] A further advantageous embodiment proposes that the adaptive
correction of the breakdown values be carried out only at certain
operating points and/or within certain operating ranges and/or time
ranges.
[0094] Furthermore, it can be advantageous if the adaption can be
active when the control is inactive. In this context, "inactive"
can denote that the control does not engage in or cause or carry
out any activity of the setting member since, for example, an
operating range is selected or actually exists in which a torque
follow-up is not carried out but, instead, a stationary value is
set. In this operating range, one can carry out an adaption of the
parameter without carrying out an active control.
[0095] Furthermore, it can be advantageous if the adaption is not
carried out within special operational ranges, especially in the
event of pronounced acceleration.
[0096] It can be expedient if, within the operating ranges of
inactive adaption, one utilizes correction values of the setting
values which were detected within the previously determined
operating ranges of active adaption. Furthermore, for such
procedure, it may be expedient if the previously detected values
for an adaption are stored in an intermediate memory and can be
addressed in situations of a deactivated adaption.
[0097] In a further embodiment of the invention, it may be
expedient if, within the operating ranges of inactive adaption, one
applies correction values of the breakdown values which can be
extrapolated with active adaption from correction values in
previously detected operating ranges.
[0098] In accordance with a further method according to the
invention, it can be expedient if one adopts virtual breakdown
models and/or virtual breakdown values for the areas of the engine
torque and/or for the area of the net engine torque, after taking
into account the secondary consumers,and/or for the desired clutch
torque.
[0099] Furthermore, it can be advantageous if one introduces and/or
employs the inverse transfer function of the transmitting unit with
setting member as a virtual breakdown source.
[0100] Furthermore, it can be expedient if the characteristic field
of the engine is used as the virtual breakdown source.
[0101] It is particularly advantageous if virtual breakdown sources
are used to define breakdown values whose original causes cannot be
localized, such as for example straying in the region of
manufacturing tolerances of the individual component parts.
[0102] A further novel concept of the invention relates to a method
of controlling a torque transmission system with or without load
distribution wherein the clutch torque adapted to be transmitted
from an input side to an output side of the torque transmission
system is used as a control value and such control value is put to
use by means of a setting member to which is assigned a setting
value which is functionally dependent upon the transmittable clutch
torque, so that the transmittable clutch torque always lies within
a predetermined tolerance band around the slip limit, and the slip
limit is reached at the exact time when the action of the torque
developing at the input side exceeds that clutch torque which can
be transmitted by the torque transmitting parts.
[0103] Furthermore, it can be advantageous if the setting member is
assigned as a setting value a value which corresponds to the clutch
torque adapted to be transmitted between the torque transmitting
parts of the torque transmission system.
[0104] A further expedient development of the invention proposes
that the setting value be determined in dependency upon a
transmittable clutch torque and that, in order to calculate such
transmittable clutch torque, one establishes a difference between
the value of the driving torque and a correction value wherein the
correction value is increased or reduced in dependency upon at
least one condition value of the torque transmission system.
[0105] Furthermore, it can be expedient if the correction value is
determined in dependency upon a differential RPM between an input
RPM and an output RPM, designated slip RPM, the correction value
being increased as long as the slip RPM is below a predetermined
threshold slip value and the correction value being reduced as long
as the slip RPM is above such or another predetermined threshold
slip value.
[0106] Furthermore, it can be of advantage if the correction values
are increased incrementally as long as the slip RPM is below the
one threshold slip value and the correction value is reduced
stepwise as long as the slip RPM is above the one or another
threshold slip value. Stopping phases of adjustable length are
provided between the relevant stages and, during each stopping
stage, the correction value is kept constant at a value set at the
outset of each stopping stage.
[0107] Furthermore, it can be advantageous if the times during
which the input RPM exceeds the output RPM by a defined slip RPM
are recognized as the slip phase and at the end of each slip phase
the correction value is set again to a definite value.
[0108] An advantageous embodiment of the invention proposes that
the times during which the input RPM exceeds the output RPM by a
definite slip RPM be recognized as slip phases, and that the
relevant correction value at which the slip RPM assumes its maximum
value be stored in an intermediate memory and at the end of a slip
phase the actual correction value be again replaced by the stored
correction value.
[0109] It can likewise be advantageous if the correction value be
kept constant at its relevant value for a fixable interval of time
at the end of each slip phase. According to another embodiment of
the invention, it can be advantageous if the setting member is
assigned a preset value in dependency upon a characteristic field
or a characteristic line which embraces the area of all
transmissible clutch torques or has at least one partial area
within which only one preset value is allocated for the setting
member for all transmissible clutch torques.
[0110] Furthermore, it can be advantageous that, in order to
calculate the transmissible clutch torque, one forms a difference
between an input torque value and the correction value, and this
difference is increased by a torque value which is dependent upon
slip.
[0111] According to a further embodiment of the invention, it may
be of advantage if the rise of the actual clutch torque is
restricted in the form of a gradient restriction in that the
relevant actual value of the transmissible clutch torque is
compared with a comparison torque value which consists of a
previously detected transmissible clutch torque value and an
additive fixable limiting value and that, in dependency upon such
comparison, the smaller torque value is assigned to the setting
member as the new preset value.
[0112] It can be particularly advantageous if several condition
values, such as for example the engine RPM, throttle valve angle
and/or suction intake pressure, are ascertained from a combustion
engine mounted at the input side of the torque transmission system
and the input torque of the combustion engine is detected from
these condition values by means of stored characteristic lines or
characteristic line fields. Furthermore, the invention proposes
that eventual branchings of output between the drive and the torque
transmission system be monitored at least partially or at least
temporarily and the thus obtained measured values be used to
calculate the input torque actually arising at the input side of
the torque transmission system.
[0113] It can be advantageous if each time a part of the input
torque corresponding to a proportion factor be used to calculate
the transmissible clutch torque and if such proportion factor is
determined each time from the stored characteristic line fields or
characteristic lines.
[0114] Furthermore, it can be expedient if, with torque
transmission systems without load distribution, a load distribution
is reconstructed through a slave control program.
[0115] According to the inventive concept, it can be advantageous
if measurable breakdown values, such as in particular temperatures
and/or RPM, are detected and are compensated for at least partially
through a parameter adaption and/or through a system adaption.
[0116] An expedient further development proposes that indirectly
measurable breakdown values of the control method, such as in
particular aging and/or straying of individual component parts of
the torque transmission system, be detected by monitoring some
condition values of the torque transmission system and, in
dependency upon such monitoring, the actually affected parameters
are recognized and corrected and/or virtual breakdown sources which
can be switched on in the form of program modules are used in order
to correct and/or compensate for the influence of the breakdown
values.
[0117] Furthermore, it can be advantageous if a first engagement of
the clutch is made possible only subsequent to checking of the
authority of the user.
[0118] It can likewise be advantageous if a display, such as a user
display, is controlled in dependency upon the status of the control
method in such a way that a switching recommendation is given for
the user. This switching recommendation can be carried out through
the display in an optical manner or, alternatively, in an acoustic
manner.
[0119] It can also be advantageous if phases of idleness,
particularly of a vehicle, are recognized by monitoring significant
operating values, such as accelerator pedal and/or gear linkage
position and/or tacho RPM and, upon elapse of a defined time
period, the driving unit is arrested and restarted when
necessary.
[0120] Furthermore, it can be advantageous if operating phases of
the torque transmission system with minimal or without load takeoff
are recognized as freewheel phases and if the clutch is disengaged
during such freewheel phases and is reengaged at the end of the
freewheel phase. The end of the freewheel phase can take place or
can be recognized, for example, through a detected change of the
position of the load lever and/or of the load lever gradient.
[0121] According to a further embodiment of the invention, an
antiblocking system can be assisted by applying the control method
in such a way that, when the ABS system is active, the clutch is
completely disengaged.
[0122] Furthermore, it can be advantageous if the setting member is
controlled within certain operating ranges after actuation of the
antislip control.
[0123] The invention not only relates to the aforedescribed method
of controlling a torque transmission system but also relates
especially to a torque transmission system for the transmission of
torque from an input side to an output side wherein an internal
combustion engine, such as a motor, is disposed at the input side
and a gearbox is disposed at the output side and the torque
transmission system has a clutch, a setting member and a control
device.
[0124] Furthermore, the invention relates to a torque transmission
system which can be controlled by means of the method described
above and serves to transmit torque from an input side to an output
side, wherein the output of the torque transmission system is
connected in the power flow of a driving unit, such as a combustion
engine, and a variable-transmission device, such as a gearbox, is
installed in the power flow at the upstream or at the downstream
side, and the torque transmission system comprises or contains a
clutch and/or a torque converter with lockup clutch and/or a
starting clutch and/or a turning set clutch and/or a safety clutch
for limiting the transmissible torque, a setting member and a
control device.
[0125] According to the inventive concept, particularly
advantageous if the clutch is a self-adjusting or self resetting
clutch.
[0126] It can be equally advantageous if the clutch automatically
adjusts or compensates for wear, for example, upon the friction
linings.
[0127] According to the inventive concept, it can be of advantage
in actual practice of the invention if, in order to transmit the
torque from an input side to an output side, the torque
transmission system have a clutch, a setting member and a control
unit wherein the clutch is operatively connected with the setting
member through a hydraulic conduit which contains a slave clutch
cylinder and the setting member is actuated by the control
unit.
[0128] A further advantage resides in the utilization of a setting
member having an electric motor which acts through an eccentric
upon a hydraulic master cylinder which is attached to the hydraulic
conduit which, in turn, is connected to the clutch, a clutch path
sensor being mounted in the housing of the setting member.
[0129] In order to achieve a compact and flexible solution for the
arrangement of the device according to the invention, it is
advantageous if the electric motor, the eccentric, the master
cylinder, the clutch path sensor and the required control and load
electronics are mounted in the housing of the setting member.
[0130] It can likewise be of advantage if the axes of the electric
motor and of the master cylinder are mounted to extend in
parallelism with each other. It is particularly advantageous if the
axes of the electric motor and of the master cylinder are mounted
to extend in parallelism with each other in two different planes
and are operatively connected to each other by the eccentric.
[0131] It can furthermore be of advantage if the axis of the
electric motor extends in parallelism with a plane which is formed
essentially by the board of the control and output electronics.
[0132] According to a further development of the novel torque
transmission system, the mode of operation of the transmission
system can be optimized by mounting a spring concentrically with
the axis of the master cylinder in the housing for the setting
member.
[0133] Furthermore, it can be advantageous if a spring is mounted
in the housing of the master cylinder concentrically with the axis
of the master cylinder.
[0134] It can be advantageous for the functioning of the apparatus
according to the invention if a characteristic curve of the spring
is selected in such a way that the maximum force to be applied by
the electric motor to engage and disengage the clutch is
approximately the same in the pull and push directions.
[0135] Furthermore, it can be advantageous if the characteristic
curve of the spring is designed in such a way that the resulting
progress of the forces acting upon the clutch is linearized during
disengagement and engagement of the clutch. According to a further
development, the power requirement and thus the size of the
electric motor is minimized. Those forces which are required for
the disengagement of the clutch are decisive for the dimensioning
of the electric motor to be used since a greater force is needed
for the disengagement than for the engagement of the clutch because
the force of the spring assists the disengagement and, therefore,
one can use a weaker electric motor.
[0136] By using a spring within the master cylinder piston, no
additional space is required for the spring.
[0137] Furthermore, it can be of advantage if the electric motor
having a motor output shaft acts upon a segment wheel through a
worm and the segment wheel carries a crank which is operatively
connected with the piston of the master cylinder by a piston rod in
such a way that it is possible to transmit pushing and pulling
forces.
[0138] It can likewise be of advantage if the worm and the segment
wheel constitute a self-locking transmission.
[0139] The invention does not, however, relate only to the
aforedescribed method of controlling a torque transmission system
and to the torque transmission system itself, but also encompasses
a monitoring method for a torque transmission system with a
manually actuatable gearbox, wherein relevant gear lever positions
and an input torque of a driving unit at the input side are
detected with a sensor system and at least one corresponding gear
lever signal and at least one comparison signal are recorded and
different possible characteristics of the progress of these
signals, such as for example a difference, are recognized and
identified as the switching intention and a switching intention
signal is then transmitted to a clutch operating system at the
output side.
[0140] As concerns the inventive concept, it can be advantageous if
at least one progress of the gear lever signal is evaluated to
detect the selected gear and such information is used to identify a
switching intention.
[0141] The monitoring method ascertains the gear which is engaged
at that time, and such information can be used to determine the
comparison signal.
[0142] In this manner, one provides a method with which an eventual
switching intention of the user is recognized at a high speed and
in a highly reliable manner without it being necessary to use a
specific sensor. A predominantly automated torque transmission
system requires early information regarding a possible switching
intention in order to disengage the clutch in good time.
[0143] It can be advantageous if a gear lever signal and a
comparison signal are evaluated in such a way that intersecting
points of these signal paths are detected and then a switching
intention signal is transmitted to the clutch operating system at
the output side. If, in order to detect the switching intention,
only two signal paths are investigated or evaluated for
intersecting points, there is no longer any need for expensive
software or hardware.
[0144] According to the inventive concept, it can be advantageous
if, with the switching gearbox, a selection path is differentiated
between the switching lanes and a switching path within the
switching lanes. The switching path and/or the selection path can
be monitored in order to determine the relevant gear lever
position.
[0145] Also, there is no need for additional sensor systems for the
generation of the comparison signal since, as a rule, the single
input value (namely the input torque) can already be determined.
Since the comparison signal is formed from a filter signal wherein
the filter signal is intensified and/or weakened by a constant
value and an offset signal, it is practically ensured that the gear
lever signal and the comparison signal intersect only if a
switching intention actually exists.
[0146] In accordance with an advantageous further development, the
existence of a switching intention is detected during monitoring of
the two signal paths of the gear lever signal and the comparison
signal if an intersection point is detected and, at such time, the
switching intention is verified by means of a switching intention
counter. With the claimed switching intention counter, one ensures
that a definite interval of time elapses between the realization of
the switching intention and the transmission of the switching
intention signal, and such interval of time suffices to ascertain
whether a switching operation is actually initiated. In this
manner, the torque transmission system is effectively protected
against an unintentional release.
[0147] The gear lever signal is filtered with an adjustable time
delay in order to generate a filter signal.
[0148] It can be particularly advantageous if the gear lever signal
can be processed to form the filter signal with a PT1
characteristic.
[0149] Furthermore, it can be advantageous if the gear lever signal
is monitored and a change of the switching path within a defined
portion of the gear lever path is evaluated within a fixable
measuring period in such a way that a switching intention signal is
transmitted to devices at the output side when a fixable switching
path change threshold is not reached.
[0150] The gear lever signal, which is used to ascertain the
existence of a switching intention, which in turn is passed on, can
be tuned by means of individually adjustable filters, which are
universally usable through filter parameters, in such a way that a
wide variety of torque transmission systems can be monitored by
resorting to the same method. It is advantageous if the measuring
period is fixed in such a way that it is always clearly greater
than a half vibration period resp. vibration amplitude of the gear
lever which is not actuated during operation of the vehicle.
[0151] It can be expedient if the defined portion of the gear lever
path is outside of the gear lever path areas within which the
non-operated gear lever moves when the vehicle is in operation.
[0152] In order to practice the method according to the invention,
it is necessary as a rule to average the gear lever vibration
periods. In this manner, the duration of the measuring period can
be fixed in dependency upon the formation of average value of the
gear lever vibration period.
[0153] In accordance with a further development, one can ascertain
whether the gear lever vibrates freely during operation of the
vehicle or has a different vibration behavior, especially when a
hand is placed thereon. The mean value formation to determine the
length of the measuring periods is carried out in dependency upon
the results of such monitoring.
[0154] According to a further development of the invention, it can
be advantageous if the direction of movement of the gear lever is
detected and when such direction of movement is reversed, a control
signal is transmitted to the switching intention counter and/or an
already transmitted switching intention signal is rescinded.
[0155] In this manner, the direction of movement of the gear lever
is additionally observed and a reversal of such direction of
movement entails a rescinding of a switching intention signal which
would otherwise be transmitted as a result of vibration of the gear
lever.
[0156] Furthermore, it can be advantageous if the constant value
for the generation of the comparison signal is selected in
dependency upon the typical operating vibration amplitude of the
non-operated gear lever of the torque transmission system.
[0157] It can likewise be advantageous if the delay time with which
the filter signal is generated is caused to conform to the
vibration frequency of the gear lever which is not actuated during
operation of the vehicle.
[0158] In accordance with the inventive concept, it can be
particularly advantageous for a control method if the driving load
is monitored and, on exceeding a fixable driving load, a control
signal is transmitted to the switching intention counter. In this
manner, one can prevent that, in the event of an increased torque
at the engine side, the clutch is unintentionally disengaged or
engaged. It can likewise be advantageous if the offset signal is
applied in dependency upon the relevant throttle valve angle in a
combustion engine which is used as the driving unit.
[0159] In accordance with the inventive concept, it is expedient if
the switching or selection path of the gear lever is ascertained by
a potentiometer. It can likewise be advantageous if the switching
and/or selection path of the gear lever is ascertained by a
potentiometer in such a way that the gear setting can be recognized
by the potentiometer.
[0160] However, the invention does not relate only to the
aforediscussed method of controlling a torque transmission system
but also encompasses those processes for controlling a torque
transmission system having a device for controlling the torque
transmission system, the torque transmission system is mounted at
the output side in the power flow of a driving unit and at the
input and/or output side in the power flow of a variable
transmission device, the variable transmission device being
provided with endless flexible means which transmit torque from a
first means to a second means, the first means being operatively
connected with the input shaft of a gearbox and the second means
being operatively connected with an output shaft of the gearbox,
the endless flexible means is in frictional contact with the first
and the second means through contact pressure or tensioning and the
contact pressure or tensioning of the endless flexible means being
controlled in dependency upon the operating point, characterized in
that the torque transmission system is started with follow-up
torque, namely with a transmissible torque which is dimensioned at
each operating point in such a way that the endless flexible means
of the variable transmission device does not begin to slip. This
means that the slip limit of the torque transmission system is
controlled at each operating point so that the slip limit of the
endless flexible means is always greater and if the applied torque
is excessive, the torque transmission system always begins to slip
before the endless flexible means slips.
[0161] Furthermore, it can be advantageous if the contact pressure
and/or tensioning of the endless flexible means is determined and
applied at each operating point in dependency upon the applied
engine torque and/or the load distribution or branching off
regarding the secondary consumers and an additional safety
tolerance and the transmissible torque of the torque transmission
system is controlled in dependency upon the operating point and the
torque transmissible by the torque transmission system entails, in
the event of torque fluctuations, slippage of the torque
transmission system before the slip limit of the endless flexible
means is reached.
[0162] It is particularly expedient if the slip limit of the torque
transmission system at each operating point is lower than the slip
limit of the endless flexible means of the variable transmission
device.
[0163] In accordance with the novel concept, it can be of
additional advantage if the torque transmission system with its
slip limit dependent upon the operating point isolates and/or damps
torque fluctuations and torque surges at the input side and/or at
the output side and protects the endless flexible means against
slip. Thus, the endless flexible means is protected against
slippage because the slippage under the above outlined
circumstances could lead to destruction of the endless flexible
means and thus to a breakdown of the gearbox.
[0164] According to the inventive concept, it is expedient to
control the contact pressure or the tensioning of the endless
flexible means in dependency upon the operating point and, in
addition to the applied torque, to take into account a safe reserve
which can be caused to approximate and/or to conform to the
transmissible torque through the selection of the transmissible
torque of the torque transmission system. The adaptation of safety
torque can be carried out in this case in such a way that the
selected safety reserve can be less than in accordance with prior
art proposals.
[0165] It can be particularly advantageous if the safety reserve of
the contact pressure or tensioning is as low as possible as a
result of protection of the torque transmission system against
slip.
[0166] It is particularly expedient if the torque transmission
system slips or slides only briefly in the event of torque surges.
It is thus possible to isolate or damp or filter torque surges at
the input side or at the output side; such surges may occur in
extreme driving situations and could damage or destroy the endless
flexible means.
[0167] The invention relates not only to the aforedescribed method
but also to an apparatus, such as a variable transmission device,
which is controlled in accordance with the aforementioned method
and wherein the variable transmission device can be an infinitely
adjustable gearbox. It may be especially advantageous if the
variable transmission device is an infinitely adjustable cone
pulley belt contact gearbox. It can also be particularly
advantageous if the torque transmission system which is part of the
apparatus is a friction clutch or a converter lockup clutch or a
turning set clutch or a safety clutch. The clutch can be a dry
clutch or a wet clutch. Furthermore, it may be expedient to provide
a setting member which controls the transmissible torque and is
controlled electrically and/or hydraulically and/or mechanically
and/or pneumatically, or the actuation of the setting member is
effected by a combination of these undertakings.
[0168] The invention does not relate only to the aforedescribed
methods but especially also to an apparatus with at least one
sensor for the detection of the effective gear ratio or the engaged
gear of a gearbox, a central computer unit being provided to
process the sensor signals and to calculate the gearbox input
speed. For such calculation, it is further necessary to take into
consideration the transmission ratios, such as the transmission
ratios of the differential.
[0169] It can be of advantage if the ascertained rotational speeds
of the wheels are averaged and the thus obtained averaged signal is
utilized to ascertain or to calculate the gearbox input RPM by
taking into consideration the transmissions in the power train and
the transmission ratio of the gearbox.
[0170] It is of advantage if the rotational speed of the wheels is
ascertained by utilizing one to four sensors, and is particularly
advantageous if one employs 2 or 4 sensors.
[0171] The apparatus can be constructed in a particularly
advantageous manner and way if the sensors which serve to detect
the rotational speeds of the wheels are in signal transmitting
connection with the antiblocking system or constitute component
parts of an antiblocking system.
[0172] The invention will be explained in greater detail with
reference to an embodiment in the vehicle industry.
BRIEF DESCRIPTION OF THE DRAWINGS
[0173] There are shown in:
[0174] FIG. 1a a block diagram of a torque transmission system with
load distribution,
[0175] FIG. 1b a block diagram of a torque transmission system
without load distribution wherein a fictitious load distribution is
copied through a slave control program,
[0176] FIG. 2a to 2e diagrammatic illustrations of different
physical properties of a torque transmission system as a function
of the torque division factor K.sub.ME;
[0177] 2a: acoustics as a function of K.sub.ME;
[0178] 2b: thermal stressing as a function of K.sub.ME;
[0179] 2c: pulling force as a function of K.sub.ME;
[0180] 2d: fuel consumption as a function of K.sub.ME;
[0181] 2e: load change behavior as a function of K.sub.ME,
[0182] FIG. 3 a block diagram resp. a signal diagram of a control
method with adaption,
[0183] FIG. 4 a block diagram resp. a signal diagram of a control
method with adaption,
[0184] FIG. 5a to 5 c the effect of disturbance values upon the
torque as a function of time; a: additive interference through,
e.g., additional aggregates; b: multiplicative interferences; c:
additive disturbance values,
[0185] FIG. 6 a characteristic correction field of engine torque as
a function of the engine torque and the RPM,
[0186] FIG. 6a a diagrammatic illustration of a breaking up of a
characteristic field,
[0187] FIG. 6b a diagrammatic illustration of a breaking up of a
characteristic field,
[0188] FIG. 7 a block diagram for the control method with
adaption,
[0189] FIG. 8 a block diagram for a control method with
adaption,
[0190] FIG. 9 a block diagram for a control method with
adaption,
[0191] FIG. 10 a diagrammatic illustration of a vehicle with a
torque transmission system,
[0192] FIG. 11a a longitudinal sectional view through a setting
member unit of a torque transmission system,
[0193] FIG. 11b a cross sectional view of the setting member unit
at III,
[0194] FIG. 12a a longitudinal sectional view of a setting member
unit in a torque transmission system,
[0195] FIG. 12b a cross sectional view of the setting member unit
at IV,
[0196] FIG. 13 a force diagram showing the behavior of the setting
member,
[0197] FIG. 14 a diagram for the determination of a clutch
torque,
[0198] FIG. 15 a characteristic line field for the determination of
the position of a setting member,
[0199] FIG. 15a to 15e diagrams of the positioning of the setting
member as a function of time,
[0200] FIG. 16 a circuit diagram of a manual gearbox,
[0201] FIG. 17 a signal diagram for detecting the switching
intention,
[0202] FIG. 18 a signal diagram for the generation of a comparison
signal,
[0203] FIG. 19 a further signal diagram for ascertaining the
switching intention,
[0204] FIG. 20 a signal diagram for verification of the detection
of the switching intention,
[0205] FIG. 21 a functional diagram of an electrohydraulically
controlled torque transmission system,
[0206] FIG. 22 a characteristic curve,
[0207] FIG. 23 a block circuit diagram,
[0208] FIG. 24 the progress of a signal as a function of time,
[0209] FIG. 25 the progress of a signal as a function of time,
[0210] FIG. 26 the progress of a signal as a function of time,
[0211] FIG. 27 the progress of a signal as a function of time,
[0212] FIG. 28 a characteristic curve with support position
adaption,
[0213] FIG. 29a a gearbox with a torque transmission system
disposed at the input side, and
[0214] FIG. 29b a gearbox with a torque transmission system
disposed at the output side.
[0215] Each of the FIGS. 1a and 1b is a diagrammatic illustration
of a portion of a power train in a vehicle wherein a driving torque
is being transmitted by an engine 1 with a mass moment of inertia 2
to a torque transmitting system 3. The torque which can be
transmitted by the torque transmitting system 3 can be transmitted,
for example, to a downstream part in a gearbox, such as an input
part, and such part is not explained in detail.
[0216] FIG. 1a is a diagrammatic illustration of a torque
transmission system 3 with load branching or distribution or
splitting wherein, for example, a Fottinger clutch or a
hydrodynamic torque converter 3a is disposed in the power flow and
is connected in parallel with a converter lockup clutch 3b. A
control unit regulates the operation of the torque transmitting
system 3 in such a way that, at least under certain operating
conditions, the applied torque is transmitted substantially in
parallel, either only by the hydrodynamic torque converter 3a, only
by the Fbttinger clutch or the converter lockup clutch 3b, or
simultaneously by the two torque transmitting devices 3a, 3b.
[0217] In some of the operating ranges, it may be desirable to
resort to intentionally transmittable torque between the selected
parallel torque transmission devices 3a, 3b and can be carried out
accordingly. The ratio of the torque being transmitted, for
example, by the converter lockup clutch 3b and the hydrodynamic
torque converter can be caused to conform to specific requirements
within the individual operating ranges.
[0218] FIG. 1b is a diagrammatic illustration of a torque
transmission system 3 without load distribution. A torque
transmission system 3 of such kind without load distribution can
constitute, for example, a clutch, such as a friction clutch and/or
a turning set clutch and/or a starting clutch and/or a safety
clutch. A slave control program copies a fictitious load
distribution and controls the torque transmission system
accordingly.
[0219] The diagrammatic sketches or block diagrams which are shown
in FIGS. 1a and 1b and form part of a partially illustrated power
train, with the torque transmitting system 3 mounted in the power
flow at the input side with or without load distribution, merely
constitute examples of possible arrangements or designs of torque
transmission systems.
[0220] Furthermore, it is also possible to employ arrangements of
torque transmission systems wherein the selected torque
transmission system can be mounted in the power flow upstream or
downstream of the component part or parts determining the
transmission ratio of the gearbox. Thus, for example, a torque
transmission system (such as a clutch) can be mounted in the power
flow upstream or downstream of the variator of an infinitely
adjustable cone pulley belt contact gearbox.
[0221] An infinitely adjustable gearbox, such as an infinitely
adjustable cone pulley belt contact gearbox, can likewise be
realized with a torque transmission system mounted at the input
side or at the output side.
[0222] Systems with load distribution of the character shown in
Figure 1a, such as a hydrodynamic torque converter 3a with lockup
clutch 3b, can be controlled by resorting to a control method
according to the invention in such a way that the torque which can
be transmitted by the individual parallel-connected torque
transmission systems, such as the torque converter 3a and the
lockup clutch 3b, is adapted to be started or controlled. As a
rule, the transmission of torque to be transmitted by one of the
two torque transmission systems which are arranged in parallel is
started and the torque which is to be transmitted by the torque
transmission system connected in parallel therewith is set
automatically.
[0223] As a rule, in torque transmission systems with more (N) than
two parallel-connected transmission systems, the torques which can
be transmitted must be controlled by (N-1) transmission systems and
the transmittable torque of the (N-th) transmission system is then
set automatically.
[0224] In systems without load distribution, such as, e.g., in a
friction clutch, the transmission of torque can be initiated
through a control loop, which underlies the control, in such a way
that the control simulates a system with fictitious load
distribution. The friction clutch 3c is adjusted by such control,
e.g., to a desired value which is less than 100% of the
transmissible torque. The difference between the thus selected
desired torque and the 100% of the entire transmittable torque is
established by the controls through a slip-dependent safety clutch
3d. In this manner, one ensures that, on the one hand, the friction
clutch is not engaged with a contact pressure higher than that
which would be necessary for the transmission of the required
torque and, on the other hand, due to the operation with slip, one
can ensure a damping of torsional vibrations and peak values of
torque, such as surges of the torque in the power train.
[0225] Within another stage of the operating range of the torque
transmission system, it can be advantageous if the torque
transmission system (such as a friction clutch or another clutch)
is engaged with a low but well-defined overpressure or excessive
contact pressure. Within these operating ranges (e.g., at high
rotational speeds), it is now possible to avoid pronounced slip and
to thus also avoid excessive consumption of fuel by the internal
combustion engine.
[0226] With a contact pressure at about 110% of the applied
averaged torque, it is possible to establish an intentional slip or
sliding of the clutch in response to the development of
short-lasting peak values of torque. Thus, a damping of the peak
values can be achieved with a substantially engaged clutch.
[0227] Furthermore, it is possible to damp or insulate surges of
torque having peak values by operating the clutch with only slight
overpressure in order to establish a short-lasting slip or sliding
of the clutch.
[0228] That parameter which is characteristic of the division of
torque between the parallel-connected torque transmission devices
of the torque transmission system 3 is the torque dividing factor
K.sup.ME which is defined by the ratio of torque adapted to be
transmitted by a clutch or another torque transmission device (such
as, e.g., a converter lockup clutch) to the entire torque which can
be transmitted by the torque transmission system.
[0229] The torque dividing or division factor KME thus indicates
the ratio of the transmissible torque, e.g., of that torque which
can be transmitted by a clutch 3b, to the overall transmissible
torque.
[0230] When the value of K.sub.ME is less than one, this indicates
that the transmissible torque is divided between the
parallel-connected devices 3a, 3b and the torque being actually
transmitted by the device 3a or 3b is less than the overall applied
torque or the overall torque to be transmitted.
[0231] When K.sub.ME=1, the transmissible torque is being
transmitted only by one of the parallel-connected devices 3a, 3b,
especially by the clutch 3b. If the torque develops temporary peaks
with values which are above the value of the transmissible torque,
this can result in a slip or sliding of the clutch or of the torque
transmission devices. However, if the operating range has no torque
peaks, the entire torque is being transmitted by one of the devices
3a, 3b.
[0232] If the value of K.sub.ME exceeds one, the entire applied
torque is likewise transferred by one device; however, for example,
the contact pressure of the clutch corresponds to a transmissible
torque which is greater than the applied torque. It is thus
possible to filter off greater torque irregularities which lie
above a threshold value and slight torque irregularities are not
filtered.
[0233] A further advantage of a defined overpressure, as opposed to
the completely engaged clutch, is the shorter reaction time of the
system until, for example, the clutch is disengaged. The system
need not disengage the clutch from the completely engaged condition
but only from the actually existing condition. However, a slightly
slower actuator can be used at the same interval of time.
[0234] FIGS. 2a to 2e illustrate the behavior of physical
characteristics or physical values of torque transmission systems
as a function of the torque division factor K.sub.ME, with
reference to a hydrodynamic torque converter with a converter
lockup clutch. The plus and minus signs along the ordinates
indicate more positive or more negative influences of the KME
factor upon the illustrated physical properties.
[0235] FIG. 2a shows the acoustic properties of the power train of
a motor vehicle. The curves indicate the progress of torques being
transmitted by a torque transmission system with a damper and the
progress of torque being transmitted by a torque transmission
system without a damper, as a function of K.sub.ME. The curves for
the two torque transmission systems, with and without damper, run
parallel as a function of K.sub.ME. The torque transmission system
with a damper has a slightly improved quality regarding acoustics
as compared with the torque transmission system without a
damper.
[0236] It can be seen that, as a function of the value of K.sub.ME,
when K.sub.ME=0, the acoustics assume their most favorable value.
With increasing K.sub.ME, the acoustic properties drop monotonously
until, at high K.sub.ME values, the acoustic properties show a
transition to a value which is independent of K.sub.ME.
[0237] Such behavior of the acoustic properties in dependency upon
the torque division factor K.sub.ME can be explained through the
increased uncoupling of the power train from the torque
irregularities and torque peaks of the driving aggregate as a
result of an increase of slip as a function of a reduced K.sub.ME
value.
[0238] With decreasing slip in the torque transmission system and
increasing K.sub.ME, the torque irregularities in the drive train
are transmitted more pronouncedly and the damping action is reduced
simultaneously until, at a certain K.sub.ME value, the damping
becomes minimal or no longer exists at all. Thus, a constant
acoustic behavior can be arrived at as a function of a further
rising K.sub.ME value. The K.sub.ME value at which a constant
acoustic behavior is established as a function of the torque
division factor is dependent upon the then existing characteristic
of the power train. With characteristic systems, this value lies at
about K.sub.ME=2. At this value, the clutch of the torque
transmission system is engaged to such an extent that practically
each and every torque fluctuation is being transmitted.
[0239] FIG. 2b shows the thermal stressing of a hydrodynamic torque
converter with a converter lockup clutch as a function of the
K.sub.ME value. The expression "thermal stressing" can denote, for
example, the energy input into the system as the result of friction
or as the result of different speeds of the component parts. More
specifically, for example, one can take into consideration the
energy input in a torque converter or into the fluid of a torque
converter. Likewise, such term can denote the energy input into the
friction faces of a converter lockup clutch and/or friction
clutch.
[0240] The low value of the thermal stressing when K.sub.ME=0 rises
with an increased value of K.sub.ME. The expression "thermal
stressing" is intended to denote, inter alia, the energy input as a
result of differences of RPM. With an increasing K.sub.ME, the
energy input decreases as a result of speed differences in the
converter until, when K.sub.ME=1, the converter lockup clutch is
engaged and the RPM differences equal zero; therefore, the thermal
stressing assumes its most favorable value. For K.sub.ME.gtoreq.1,
the thermal stressing is constant and equal to the value for
K.sub.ME=1.
[0241] FIG. 2c shows the change of the pulling force which
decreases as a function of a rising K.sub.ME value since, at a low
K.sub.ME; value, the conversion area of the torque converter is put
to better use and/or the low K.sub.ME allows another, more
favorable, operating point of the internal combustion engine to be
achieved.
[0242] FIG. 2d shows a fuel consumption which becomes more
favorable as the K.sub.ME value rises. Owing to a reduced slip, for
example, in the range of the hydrodynamic torque converter, it is
possible for the fuel consumption to be reduced with a clutch which
becomes increasingly engaged as the K.sub.ME value rises.
[0243] FIG. 2e shows the load change behavior as a function of the
K.sub.ME value. The load change behavior is shown to be most
satisfactory when K.sub.ME=1, i.e., with a clutch engaged in this
manner, the torque which can be transmitted by the clutch
corresponds exactly to the applied torque.
[0244] FIG. 3 is a diagrammatic illustration of a block circuit
diagram of a control method. In this diagram, the setting member
and the control circuit are denoted by a block 4. The control
method 5 and the adaption 6 (system adaption and/or parameter
adaption) can likewise be denoted by common blocks.
[0245] The control path with a setting member, or a transmission
unit with a setting member 31, and the disturbances acting upon
such system are denoted by the block 4. A driving assembly 16, such
as an internal combustion engine or motor, transmits an engine
torque M.sub.mot 33 in dependency upon the input values 14, such as
for example the quantity of injected fuel, load lever, RPM of the
driving aggregate, etc. or the characteristic system values 32,
such as temperature, etc. The engine torque M.sub.mot 33 is
branched off in part through secondary consumers 34, such as a
dynamo, a climate control, servo pumps, steering aid pumps, etc.
These secondary consumers are taken into account in the block 35 by
subtracting the branched off torque 34a from the engine torque 33
to arrive at a resulting net torque 36.
[0246] The dynamics of the engine 16 and/or power train such as,
e.g. as a result of the mass moment of inertia of the flywheel, are
considered in the block 37. The dynamics can take into account
especially the moments of inertia of the respective component parts
and the effect of such moments of inertia upon the net input
torque. The torque M.sub.dyn 38, which is corrected in view of the
dynamics of the system, is transmitted through a transmission unit
with a setting member or selector 31 and is transmitted from there
as the actual clutch torque 48 to the gearbox or to the vehicle 39
connected to the output of the gearbox.
[0247] The transmission unit 31 with a setting member 31 is
influenced by the values 40, such as the temperature, the friction
coefficient of the friction linings, the rotational speeds (RPM),
the slip, etc. In addition, the transmission unit like the motor 16
can be disturbed and/or influenced through tolerances, aging or
interference (unanticipated undesirable influences) by influence
values which cannot be directly measured. Such influencing is
represented by the block 41.
[0248] The adaption 6 can be divided basically into three areas. On
the one hand, one takes into account the secondary consumers or
secondary assemblies 7, and the adaption strategies or adaption
procedures related thereto are used in the adaption of the
breakdown or disturbance values and the influence of such breakdown
values. The secondary consumers can include the climate control,
the dynamo, the steering aid pump, the servo pumps and additional
secondary consumers which cause a division or branching off of the
torque.
[0249] In order to compensate for the secondary consumers 7,
signals and data 8 pertaining to these secondary consumers 7 are
used in order to be in a position to determine and/or calculate the
status of the secondary consumers 7. The status indicates, inter
alia, whether a particular secondary consumer branches off a torque
because it is switched on or switched off and, if it is switched
on, how great the branched off torque is at the corresponding point
of time.
[0250] FIG. 3 makes it clear that, in addition to the secondary
consumer adaption 7, the system adaption distinguishes between
first and second adaption loops 9, 11. The influences of measurable
breakdown values 10 are considered in the first adaption loop 9.
The influences of only indirectly measurable breakdown or
disturbance values or straying in the light of directly measurable
deviations and system condition values 12 are ascertained in the
second adaption loop 11.
[0251] A correction and/or compensation for such breakdown
influences is carried out either by changing the parameters which
influence the breakdown values and/or in that the breakdown values
are reconstructed by virtual breakdown values and are compensated
for on the basis of such virtual breakdown values.
[0252] In both instances, the breakdown value is corrected or
compensated for so that the breakdown influences or the breakdown
values are eliminated or reduced to a permissible level. By copying
the breakdown values with virtual breakdown values, the actual
cause of a breakdown cannot be localized conclusively; however, the
influence of the breakdown value upon the overall system can be
positively influenced in the above sense.
[0253] FIG. 3 further shows a block circuit diagram of a torque
system regulation with adaption and its cooperation with a selected
path and setting member. The torque regulation to be described
hereinafter can be used for systems, such as torque transmission
systems, with or without load distribution or branching off.
[0254] Compensation or adaption for the secondary consumers takes
place in the adaption block 7. The secondary assemblies, such as,
e.g., a dynamo, a steering wheel pump or a climate control,
establish one branch of the torque- and/or output flow in that a
part of the input torque M.sub.mot supplied by the engine is taken
up by the corresponding aggregate. For a clutch regulation, this
means that one proceeds from an input torque M.sub.mot which is not
actually available, i.e., that the desired clutch torque derived
from the supposedly higher engine torque, and hence also the thus
detected correcting variable or setting value, are excessive.
[0255] The detection of such load distribution which, hereinafter,
will be designated, as adaption of the secondary consumers, can
occur for example by evaluating corresponding additional signals
denoting measured values, such as the switching on or switching off
of the climate control compressor, climate control unit and other
secondary consumers.
[0256] Correction for interferences which can be caused by
measurable values, such as for example temperatures (e.g., the
cooling water temperature has an effect upon the engine torque) or
RPM or the friction coefficient can be changed due to slip, is
carried out in a second adaption loop 9. Hereinafter, such
corrections will be designated as "adaption 1". In this case, a
correction and/or compensation can take place either through
parameter adaption, e.g., a correction of the friction value, in
the further compensation block 28 or in the transfer block 30 as a
function of temperature or by a system adaption in the form of
theoretically or empirically established disturbance or breakdown
models or patterns, e.g., a non-linear correction of the engine
torque as a function of temperature.
[0257] In the third adaption block 11, interferences--which can be
caused through non-measurable system input values and/or aging
and/or straying--are corrected and/or compensated for. Since this
class of disturbances, such as e.g., aging or straying, cannot be
detected on the basis of measurable input values, it must be
detected by observing system reactions. This means that such
disturbances cannot be compensated for by preventive undertakings
prior to actually taking effect; instead, the reaction of the
system as a deviation from the expected behavior must be observed
to be thereafter corrected and/or compensated for.
[0258] These deviations can either be measured directly, e.g., by
means of a torque sensor at the clutch or, alternatively, they can
be calculated from other measured values by resorting to a method
model or pattern. In the event of detection, it is necessary to
obtain corresponding characteristic reference fields or unequivocal
reference values of the system. In order to compensate for a thus
detected disturbance or breakdown, it is necessary either to
thereupon localize (single out) and correct the source of the
breakdown or, alternatively, one assumes for example the existence
of a virtual breakdown source A or B at which the detected
deviation is corrected. In the same way, a disturbance or breakdown
can be attributed to an existing block, such as for example the
engine block 13 or the inverse transmission function of the
transmission unit in the transmission block 30.
[0259] The ascribing of the disturbance can be fictitious, i.e.,
such a block is not actually responsible for the disturbance.
Therefore, and in contrast with the regulation, the detection of
the condition values or parameters need not be carried out
permanently and can be limited to certain operating ranges.
[0260] In those phases where no adaption takes place, one utilizes
the adapted parameters which were detected during an earlier
adaption phase.
[0261] As shown in FIG. 3, the input torque 15 M.sub.mot supplied
by the driving assembly 16, such as for example an internal
combustion engine, is formed and/or calculated in the
characteristic engine block 13 from a variety of input values
14.
[0262] The values which are used to this end comprise at least two
of the following values, namely the RPM of the driving aggregate,
the load lever position or the accelerator pedal position denoting
the rate of fuel delivery, the subatmospheric pressure in the
suction intake manifold, the injection time, the fuel consumption,
etc. Furthermore, when forming or calculating the input torque
M.sub.mot 15, it is possible to process the information already
obtained and relating to possible breakdown influences (wear,
temperature).
[0263] In the interlinking block 17, there is established an
interlinking which effects a correction of the driving torque by
taking into account the secondary consumers in the adaption block
7. Such correction is carried out additively in such a way that the
branched off torques of the secondary consumers detected in 7 are
subtracted from the engine torque 15 M.sub.mot. Hereinafter, this
corrected engine torque will be referred to as M.sub.Netto 18. The
engine torque which is corrected by the branched off torques of the
secondary consumers constitutes the input value for the block 19
which serves as a compensation block for the breakdown value
correction or comparison. By resorting to corresponding correction
factors or corrective undertakings, the compensation block 19
renders it possible to simulate breakdown sources whose breakdown
values are or can be comparable to the actually occurring breakdown
values. The virtual breakdown values are returned to the adaption
block 9 and constitute the balance of the difference between (a)
the deviations and/or fluctuations which occur in the system as a
result of for example manufacturing tolerances, contamination, etc.
and (b) the desired conditions.
[0264] The correction can be carried out through additive,
multiplicative, functional and/or non-linear proportions. In
general, it is of importance to compensate for or to reduce the
effect of the disturbances to an acceptable level within a range of
acceptable limit values. For example, additive disturbances or
breakdowns can be taken into consideration in the form of a virtual
consumer and thus superimposed upon the driving torque even if the
disturbance or breakdown has a different physical cause.
[0265] In a dynamic block 20, the dynamics of the method to be
regulated, e.g., in the form of taking into consideration the mass
moments of inertia (for example, of the moving mass of the engine)
can be subjected to follow-up control if this is advantageous for
the behavior of the system or for the control. For example, this
enhances the quality of the regulation in the event of pronounced
accelerations or delays. Hereinafter, the thus dynamically
corrected driving torque 21 will also be designated as
M.sub.AN.
[0266] In an operating point detection block 22, the desired clutch
torque M.sub.KSoll is established in dependency upon the then
prevailing operating point. This is calculated from a percentual
share of the dynamically corrected torque MAN and a safety torque
M.sub.Sicher which is described in a safety block 25. The
percentual share is determined in a further characteristic field
block 23 by the torque division factor K.sub.ME. The percentual
share of the dynamically corrected torque can be altered by a
further correction block 24.
[0267] In systems with a genuine load distribution or branching
off, such as in the case of a converter with a lockup clutch, the
proportion of the safety function can become M.sub.Sicher=0 since a
torque is built up by way of the converter in the event of
slip.
[0268] In the case of an overall system without load distribution,
the safety function M.sub.Sicher must ensure that, for example, in
the event of slip, an additive torque is added to the existing
torque to thus prevent the buildup of an excessive slip value.
[0269] The correct proportion factor K.sub.ME for each operating
point is fixed or ascertained in the characteristic field block 23.
This factor K.sub.ME is memorized or stored in the corresponding
characteristic fields or characteristic lines in which one or more
of several values including the engine RPM, the engine torque, the
driving speed, etc. are entered. This K.sub.ME factor represents,
in the case of two systems with a load distribution in the manner
of a converter with lockup clutch, the ratio to be set by the
control between the transmissible clutch torque and the available
shaft torque.
[0270] In systems without load distribution, the direct proportion
of the torque regulation is fixed by the proportion factor
K.sub.ME. The remaining torque is transmitted in the form of
slip-dependent safety torque which is ascertained in the safety
block 25.
[0271] A further dynamic correction and/or compensation for the
previously detected percentual share of the torque can take place
in the correction block 24. This correction and/or compensation can
be carried out in such a way that one limits the rise of the
desired torque and it will hereinafter be referred to as "gradient
restriction".
[0272] For example, the gradient restriction can be carried out in
the form of a maximum permissible increment per scanning step or
through a predetermined modus operandi as a function of time. In
view of such undertaking, the activation of the power train is
restricted to a maximum permissible value and a satisfactory and
comfortable load change behavior is thereby achieved.
[0273] A safety torque M.sub.Sicher is determined in the safety
block 25 at each operating point. For example, such safety torque
can be calculated in dependency upon the slip RPM. In this case,
the safety torque would become greater in response to increasing
slip. In this manner, one can protect the clutch in systems without
load distribution.
[0274] Furthermore, a safety function of such kind renders it
possible to prevent or reduce thermal overloading of the
transmission system. The functional interdependence between the
safety torque and the slip can be described by a corresponding
function or can be predetermined through characteristic lines or
characteristic fields. The output value, namely the desired clutch
torque, of a superposed block 26 can be expressed by
MK.sub.Soll=K.sub.MEM.sub.AN+M.sub.Sicher
[0275] wherein the correction block 24 is not considered in
equation.
[0276] If the block 24 is taken into account, the desired clutch
torque can be described as
MK.sub.Soll=d.sub.Dyn(K.sub.ME*M.sub.AN)+M.sub.Sicher
[0277] wherein d.sub.Dyn (K.sub.ME*M.sub.AN) contains the
correction dynamics or accounting for the dynamics in the block
24.
[0278] The desired clutch torque is determined through those values
of the torque division factor K.sub.ME and safety torque
M.sub.Sicher 25 which are dependent upon the operating point
detected at 22.
[0279] It is possible to again carry out a correction of the
desired clutch torque M.sub.KSoll with a second virtual breakdown
source B in the further compensation block 28.
[0280] Such corrected desired clutch torque M.sub.KSollkorr 29 is
converted into a setting value in a transfer block 30 by an inverse
transmission function of the transmission unit of the setting
member 31. The transmission unit with the setting member 31 is
controlled by means of this setting value so that the transmission
unit then carries out the corresponding operations.
[0281] The transfer unit with setting member indicated at 31 is
intended to embrace, inter alia, systems with load distribution
such as torque converters with lockup clutches or systems without
load distribution in the form of a clutch, such as for example
friction clutches. For example, clutches which are used in systems
without load distribution can be wet clutches, dry clutches,
magnetic powder clutches, turning set clutches, safety clutches,
etc.
[0282] The generation of the energy/force required to operate the
setting member 31 can take place, for example, electromotorically,
hydraulically, electrohydraulically, mechanically, pneumatically or
in another way.
[0283] FIG. 4 is a block circuit diagram of a control method with
adaption and shows the overlapping control block 5 as well as
individual adaption blocks. The block 4 of the control path (not
shown in this Figure) with setting member of FIG. 3 is equally
valid for the FIG. 4 and can be taken over from FIG. 3.
[0284] Starting from the characteristic field block 13, one should
assume the presence of an engine torque 15 which is processed
additively with a correction torque 42 in such a way that the
correction torque 42 is subtracted from the engine torque 15. The
torque differential 43 is likewise additively corrected by the
branched off torques of the secondary consumers 7 and, here again,
the torques of all relevant secondary aggregates are subtracted
from the torque differential 43 in accordance with their
condition.
[0285] The thus treated moments or torques of the secondary
consumers or secondary aggregates are ascertained or calculated
from data or signals of the operating point 22 of the individual
aggregates and/or from additional signals 44, such as for example
switch on and/or changeover and/or switch off signals or typical
operational signals, such as for example current-voltage signals of
the dynamo.
[0286] For example, the detection can be carried out in that
typical operational signals are stored in a characteristic field or
a characteristic line and thus an associated torque requirement of
the secondary consumers is determined by reading a characteristic
field or a characteristic line. An equally possible alternative
mode of detection is to store equations or equation systems where
the signal values are entered as parameters and the solving of such
equations or equation systems determines the torque
requirements.
[0287] The corrected signal can undergo a dynamic correction in
dependency upon the dynamic block 20. For example, the dynamic
block 20 takes into consideration the moments of inertia of the
rotary components, such as engine parts and for example the
flywheel, or the moments of inertia of other components of the
power train. The operating point 22 is ascertained or calculated
from the condition values 40 of the system. This can be made
possible by ascertaining data from characteristic fields or by
solving the equations or equation systems, the condition values
being introduced into such equations as parameters.
[0288] For example, the torque division factor K.sub.ME 23 is
ascertained from a characteristic field at the operating point 22.
A dynamically corrected signal 46 is multiplied by the torque
division factor 23 to thus determine the torque which is
transmitted, for example, by a converter lockup clutch of a
hydrodynamic torque converter with converter lockup clutch. Again,
the signal can be corrected with assistance from the dynamic block
24.
[0289] In the example which is shown in FIG. 4, the dynamic block
24 is realized as a gradient restriction, i.e., a restriction of
the maximum rise of the torque. Thus, this gradient restriction can
be realized in such a way that the rise of the torque is compared,
as a function of time within a fixed interval of time, with a
maximum permissible value, such as for example a ramp and, when the
actual rise exceeds the maximum value of the ramp, the ramp signal
is used as the real value.
[0290] A further possibility of limiting the gradient can be
achieved with a dynamic filter. The time behavior of the filter as
a function of time can be selected in a number of ways depending
upon the operating point so that, when using for example a PT.sub.1
filter, the time constant can be set as a function of the operating
point.
[0291] As shown in FIG. 4, an output signal 47 of the block 24,
namely the desired clutch torque M.sub.KSoll, to the transfer unit
is transmitted to the transfer unit with setting member. Such
desired clutch torque is compared with the actual clutch torque
MKIST 48 at a junction 49. Such comparison is ensured by an
additive method according to which the actual clutch torque 48 is
subtracted from the desired clutch torque 47 to thus arrive at a
difference .DELTA.M 50. The torque difference .DELTA.M is processed
in the next-following blocks 51, 53, 54 of the block circuit
diagram into the correction torque 42 which is processed with the
engine torque 15 at the junction 52.
[0292] The adaption of, in this example, FIG. 4 does not carry out
any localization of the breakdown values but traces the
disturbances to fictitious breakdown values or disturbances. The
correction of and/or the compensation for real breakdown values by
means of fictitional breakdown values no longer requires a
localization and, accordingly, no longer the correction of real
causes of defects and errors. In the example of FIG. 4, the engine
torque or characteristic field of the engine is regarded as the
fictional breakdown source so that all developing errors and
disturbances are regarded as disturbances of the engine torque and
are compensated for or corrected by an engine correction torque
M.sub.mot.sub..sub.--.sub.korr.
[0293] The purpose of the adaption is to realize the most accurate
achievable setting of the torque division factor K.sub.ME as
regards the quality of reaction to disturbances and optimizing of
the physical behavior of the system.
[0294] The correction value M.sub.mot.sub..sub.--.sub.korr can be
ascertained by solving the equations or equation systems and/or by
using a characteristic correction field. The characteristic
correction field can be arrived at in such a way that the
correction value is recorded for example over two parameters. When
determining the characteristic correction field, it is possible for
example to use the same parameters through which the characteristic
engine field is recorded, such as for example the fuel consumption
and the engine RPM. However, it is also possible to use as one
parameter of this characteristic correction field a value which
reflects a dependency of the transfer function upon the path, such
as for example the turbine RPM.
[0295] The design of such a characteristic correction field over
the engine torque and the engine RPM can be effected for example by
fixing three supporting points. By resorting to three supporting
points, it is possible to fix a plane which determines the
characteristic correction field as a function of the two dimensions
or parameters. A further possibility consists in the selection of
four supporting points to define a surface which determines the
characteristic correction field. In this context, a block 51
carries out a weighting or evaluation of the supporting points as a
function of the respective operating point. This weighting of the
supporting points is carried out since an indication concerning the
correction values as at other operating points can be made over the
surface of the characteristic correction field from each operating
point. However, since this can result in errors, and the
indications in partial areas of the characteristic correction field
cannot be linearly transferred into other partial areas, one
introduces the weighting of the supporting points.
[0296] The consequence of such weighting is that, depending upon
the corresponding operating point or the region of the operating
point, the supporting points are weighted differently and thus the
influence of points in the characteristic correction field which
are more distant from the operating point has a lesser or greater
significance. The weighting of the supporting points takes place in
a block 53 which influences the time behavior of the adaption. A
block 54 constitutes a characteristic correction field block which
determines, on the basis of the operating point 22, the correction
value 42 of the engine torque and such correction value is
processed with the engine torque 15 at the junction 52.
[0297] FIGS. 5a to 5c show diagrammatically the possible
disturbances of the engine torque as a function of time. FIG. 5a
shows the desired torque as a horizontal line, and the actual
torque is shown as a horizontal line with a step. This step can be
identified as an additive portion of the engine torque which, for
example, is caused by additional aggregates. For example, a step in
the actual torque develops when an additional aggregate is turned
on, into or off a particular operating condition. Depending upon
whether the branched off load is increased or reduced, the step can
increase or lower the actual torque. Based on the height of the
step and its behavior as a function of time, it is possible to
obtain an indication as to which additional aggregate was turned
on, off or over.
[0298] FIG. 5b shows the desired torque and the actual torque at an
operating state different from that represented in FIG. 5a. The
difference between the two curves can be designated as a breakdown
value which influences a multiplicative share of the clutch torque.
Thus, a compensation and/or correction of such breakdown value must
exhibit a multiplicative characteristic.
[0299] FIG. 5c again shows the desired and actual torques but the
two torques are separated from each other by an additive portion.
The correction and/or compensation for such disturbance can be
undertaken through an additive portion of the clutch torque. For
example, the example of FIG. 5b can be explained as a result of a
change of the friction value and the example of FIG. 5c can be
explained as being based upon a deviation of the setting value.
[0300] FIG. 6 illustrates a characteristic correction field wherein
the engine correction torque is represented as a function of the
engine torque and the engine RPM. The four corner points of the
value range are used primarily as supporting points 55. The
weighting of the supporting points 55 in the block 51 of FIG. 4 can
be carried out, for example, in that at a certain operating point
the vertical positions or levels of the supporting points are
changed so that the area closely surrounding the operating point
undergoes a greater weighting. Such weighting as a result of a
change of the vertical positions of the supporting points can be
designed, depending upon the operating point, in such a way that
the change is experienced by one to four supporting points.
[0301] The fixing of the four supporting points 55 which define a
surface can also be modified in that one starts with six supporting
points 55 (see FIG. 6a) with three supporting points always
arranged along an axis and the six supporting points define two
surfaces each with four supporting points, two supporting points
being common to two surfaces.
[0302] A further embodiment can be characterized in that one
employs nine supporting points (see FIG. 6b) in order to define
four surfaces. The characteristic field is set up in such a way
that the points of each pair of neighboring supporting points
belonging to a common surface are connected with one another by a
straight line so that the definition range of such surface is
bounded by four straight lines and the projection of the
characteristic field onto the definition range constitutes a
polygon, as a rule not a rectangle or a square. The connecting
lines between two opposing straight boundary lines of the
characteristic field which lie in a common plane spanned by a
straight marginal line of the characteristic field and the axis of
the definition area of the characteristic field likewise constitute
sections of straight lines.
[0303] A further embodiment of the characteristic field of FIG. 6
can represent a curved surface which is generated in a
three-dimensional space according to a functional connection, such
as for example a parabola of the second order. The surface which
characterizes the characteristic field can be a curved surface
which is defined by certain supporting points and/or by a
functional connection or an equation or equation system.
[0304] FIG. 7 shows a block circuit diagram resp. a flow or
development diagram of a torque regulation with adaption of a
torque transmission system which will be explained in greater
detail below. For example, the torque transmission system can be a
clutch, such as a friction clutch and/or a starting clutch of an
automatic gearbox and/or a transfer means of an infinitely
adjustable cone pulley belt contact gearbox and/or a hydrodynamic
torque converter with a converter lockup clutch and/or a turning
set clutch and/or a safety clutch. The actuation of the torque
transmitting parts can be carried out by way of an
electromechanical, an electrohydraulic and/or a mechatronic and/or
a mechanical and/or a hydraulic and/or a pneumatic setting
member.
[0305] As shown in FIG. 7, the driving torque 62 of a driving
aggregate 61, especially an internal combustion engine, is first
calculated from different input values 60. The values used here
comprise at least two of the following values, namely the RPM of
the driving aggregate, the load lever position or accelerator pedal
position of the fuel supply, subatmospheric pressure in the suction
intake manifold, injection time, consumption, etc. As already
stated above, the driving aggregate is denoted by the block 61 and
the input torque of the driving aggregate is indicated at 62. The
block 63 represents a junction which effects a correction of the
input torque. Such correction is carried out by means of correction
factors which are supplied by the system adaption 64. This system
adaption 64 can constitute a program module which, based on
additional input values 65, on analytically or numerically
determined values, and on values of characteristic line fields,
carries out a correction of the average input torque. These
correction factors can compensate for deviations from a desired
state which deviations develop in the system, namely by
compensating for such deviations by additive, multiplicative and/or
nonlinear shares.
[0306] A block 66 represents the determination or selection or
calculation of a torque division factor K.sub.ME which is correct
for each existing operating condition and which (as a rule) is
between 0 and 2. However, system conditions can also occur which
render it necessary to use a larger K.sub.ME factor. This K.sub.ME
factor denotes the torque ratio M.sub.Kupplung to
M.sub.Antrieb-korrigiert to be set by the controls as one of the
values fixed in advance for each operating point in the manner of a
characteristic field from the relevant selected weighting of the
criteria indicated in FIG. 2, i.e., the K.sub.ME factor is
memorized in a characteristic field for the individual operating
conditions.
[0307] However, the K.sub.ME factor can also be considered to be
constant within the entire operating range. Fixing or calculation
of the K.sub.ME factor can also be undertaken through an equation
or through an equation system whereby the solution of the equation
or equation system determines the K.sub.ME factor.
[0308] Condition values or parameters of the vehicle and the design
of torsion dampers which may be present can be realized or
considered in the characteristic field of the K.sub.ME factor or in
the analytical equations for determining the K.sub.ME factor. The
design of the damper or dampers, if used, for example in a lockup
clutch, is of particular importance since if a damper is present,
the K.sub.ME factor can be kept constant at least within a
comparatively large section of the operating range of the internal
combustion engine or of the hydrodynamic torque converter.
[0309] A K.sub.ME factor which is kept constant within a wide
operating range can also be arrived at for clutches, such as
friction clutches or starting clutches.
[0310] The ratio of clutch torque to input torque is fixed by the
torque division factor K.sub.ME. This renders it possible to
operate, for example, with torque-controlled slip. In systems
having a load distribution (e.g., in converters with lockup
clutches), that share of the torque which is to be transmitted by
the lockup clutch is fixed by such factor. In systems without load
distribution, e.g., in clutch systems, not less than 100% of the
torque existing at the input side can be transmitted in a
stationary operation. In such instances, the factor determines that
proportion which is directly transmitted by the torque control. The
remaining share of the torque is controlled by follow up through a
slip-dependent safety torque which copies a converter-like
behavior. The calculation of the desired clutch torque is carried
out at 67 by means of the then existing KME factor, and the
corrected input torque of the driving aggregate. A further
correction of the desired clutch torque can be carried out at a
junction 68 by additive, multiplicative and/or non-linear shares
resulting from the system adaption 64. Thus, it is possible to
provide the junction 68. In this manner, one arrives at a corrected
desired clutch torque. it is sufficient, for many applications, if
only one of the two junctions 63, 68 is provided; it is preferred
to retain the junction 63.
[0311] The calculation of the setting value is carried out at 69 on
the basis of the corrected desired clutch torque of the inverse
transfer function of the path which represents the lockup clutch or
the clutch. A block 70 represents the inverse transfer function of
the setting member which is resorted to in order to calculate the
setting value which is required for a setting member 71. The
setting value thus influences a control path 72 which, in turn,
influences the vehicle 73. The value selected by a setting member
can be reintroduced into the control device in order to enhance the
quality of the control method. For example, this can relate to the
position of the master cylinder of a hydraulic system set by the
electric motor of an electrohydraulic setting member. Such
reintroduction takes place in two blocks 74 and 75. A further block
76 denotes a calculator unit which serves to simulate a model of
the vehicle and of the torque transmission system.
[0312] A block 77 denotes the transmission of those measured values
or parameters of the vehicle which are processed as input values at
another location, namely in a block 78.
[0313] The broken line denotes in FIG. 7 the transition area
between a central computer or control unit and the vehicle. The
regulator output value can be calculated at 70, and such value is
formed on the basis of the setting value ascertained at 69 and the
inverse transfer function of the setting member. The setting member
preferably constitutes an electrohydraulic or electromechanic
setting member. It is advantageous to use a proportional valve or a
pulse width modulated valve.
[0314] A feedback of the setting value can take place at 75 in the
form of a regulation or adaption. However, such feedback can be
dispensed with. A measurement of the actual clutch torque can be
carried out at 79, e.g., through a torque sensor or through an
expansion type measuring strip (DMS).
[0315] In lieu of measuring the actual clutch torque at 79, it is
also possible to carry out a calculation of such torque on the
basis of the condition values and the vehicle and converter
physics. For example, to this end the characteristic field of the
engine and/or the characteristic field of the converter or values
representing such fields can be processed in a processor or in a
central processor unit and/or they can also be stored in a memory.
Furthermore, it is also possible to memorize for this purpose a
characteristic field (or a value representing such field) denoting
the torque transmitting capacity of, e.g., a converter lockup
clutch.
[0316] If a determination of the actual clutch torque is carried
out at 79 as well as at 76, it is possible to balance the measured
actual clutch torque with the actual clutch torque which was
calculated by resorting to a model. The balancing can take place as
a logical interlinking, e.g., on the basis of the minimum-maximum
principle or as a probability comparison. The system adaption which
is shown at 64 in FIG. 7 can be utilized to carry out, inter alia,
the following comparisons and to complete the corresponding
corrections:
[0317] A: Comparison of the corrected desired clutch torque with
the actual clutch torque. Such comparison can also be made a
long-term comparison, e.g., by observing the deviation through a
simultaneously moving time window. One can make a comparison
between the corrected driving torque and the backwardly calculated
driving torque, and such comparison can also be carried out
long-term, e.g., by observing the deviations through a
simultaneously moving time window. Likewise, it is possible to
carry out an evaluation of additional signals, such as for example
switching on or off of additional aggregates, for example, the
climate control, the compressor, the gear shift, etc.
[0318] B: Detection of the system deviation determined at A into
additive, multiplicative and/or non-linear shares of M.sub.Antrieb
and M.sub.Kupplung and the resulting division into the
corresponding adaption loops 80 and 81 or into the junctions 63 and
68.
[0319] The detection or determination of the corresponding shares
of M.sub.Antrieb and M.sub.Kupplung can be carried out, for
example, according to the three diagrams of FIGS. 5a to 5c.
[0320] FIG. 7 shows a development diagram of the control method
with the individual process steps. In a first process step, a
driving torque of the engine is determined on the basis of a
plurality of input values. There follows a first correction of this
value according to the prorating by a system adaption. This system
adaption is a program module which carries out a correction of the
average driving torque on the basis of additional input values,
analytically determined values and characteristic line fields. In a
further process step, such corrected driving torque is multiplied
with a proportion factor K.sub.ME which can be between zero and
two. Such proportion factor K is memorized in a characteristic
field for the individual operating conditions. This characteristic
field can store parameters or condition values of the vehicle and
the design of the torsion damper or dampers, if any. The ratio of
clutch torque and driving torque is fixed by the proportion factor
K.sub.ME. In this manner, it is possible to achieve an operation
with controlled slip.
[0321] In systems with load distribution (converter with lockup
clutch), such factor determines that percentage of the torque which
is to be transmitted by the lockup clutch. In systems without load
distribution (clutch system without a parallel-connected
converter), not less than 100% of the torque existing at the input
side can be transmitted in a stationary operation. In this case,
the factor fixes that part of the torque which is directly
transmitted through the torque control. The remaining part of the
torque is controlled afterwards through a slip-dependent safety
torque which copies a converter-like behavior.
[0322] The achieved desired clutch torque is corrected again in a
next process step on the basis of system adaption. In this manner,
one arrives at a corrected desired clutch torque. In the last step,
a setting value is ascertained from such corrected desired clutch
torque with assistance from an inverse transfer function of the
control path. By using the inverse transfer function for the
setting member, the value appearing at the output of the control
device is obtained from such setting value. The thus obtained
output value is transmitted to the setting member which, in turn,
acts upon the control path and the vehicle. The value set by the
setting member can be retransmitted to the control device to
improve the quality of the regulating method. For example, this can
involve the position of the master cylinder as selected by the
electric motor. Furthermore, additional system values, such as for
example the clutch path, or vehicle values, can be transmitted to
the control device. These additional input values are then
introduced into the described regulating or control method through
system adaption.
[0323] FIG. 8 shows a simple model of an adaption which is limited
to additive correction of the input torque. The deviations which
result from the difference between the desired and actual clutch
torques are adapted through virtual breakdown sources. The block 61
of FIG. 8 denotes the driving aggregate, such as an internal
combustion engine, which generates an engine torque 62. A block 90
represents the adaption by means of virtual breakdown sources, and
its output signal is processed additively with the engine torque 62
at a junction 91. The corrected engine torque is corrected
dynamically in the block 2 by means of dynamic correction based
upon moments of inertia of the flywheel.
[0324] The torque arising for example at the torque converter with
lockup clutch is divided into two parts by the torque division
factor. One part is transmitted by the lockup clutch 3b, and the
differential between the existing torque and the torque transmitted
by the lockup clutch is transmitted by the torque converter 3a.
[0325] FIG. 9 shows a block or flow diagram of a control method for
torque transmission systems. The broken line in the lower half of
FIG. 9 represents the separation between the central computer unit
and the vehicle. The regulating or control method of the block
circuit diagram shown in FIG. 9 represents a simplified adaption.
The lockup clutch is started electrohydraulically through a
proportional valve or a pulse width modulated valve. The output
signal of the regulating computer or the computer output value is a
setting current which is set in proportion to a scanning ratio
being applied, for example, at a pulse width modulated output of
the computer. For example, the clutch torque results from the
pressure differential applied in this way to the converter lockup
clutch or between the two plenum chambers of the lockup clutch. The
system adaption is restricted to the adaptive correction of the
input torque whose deviation results from the difference between
the desired and actual torques.
[0326] In comparison with FIG. 7, the embodiment of the control or
regulating method according to FIG. 9 omits the junction 68 or the
return transmission of the corrected input torque (M.sub.ANkorr) In
FIG. 9, the desired pressure differential DP.sub.Soll is determined
at 100, namely as the main value in dependency upon the desired
clutch torque and, where applicable, also in dependency upon the
corrected input torque MANkorr and the turbine RPM N-turbine as
parameters.
[0327] An additional function block 101, corresponding to the block
70 of FIG. 7, is divided into two subfunction blocks 101a and 101b.
Feedback couplings 102a and 102b are provided for the respective
function blocks 101a and 101b. The input value of the inverse
transfer function of the setting member (101=101a and 101b) is the
desired pressure differential (DP.sub.Soll) which is calculated in
the block 100. The output value is obtained through the associated
scanning ratio and constitutes the regulator output value.
[0328] The setting member, which follows, is divided into an
electrical setting member portion which is formed by an end phase
and the valve winding, as well as into the hydraulic setting member
portion which is relevant for the corresponding pressure
application at the converter lockup clutch, see the block 103. The
input value of the electrical setting member portion is the
scanning ratio. This is converted at the output side into an actual
current. Depending upon this actual current (I-Ist), the hydraulic
setting member portion selects a corresponding pressure application
to the converter lockup clutch. This takes place by selecting a
corresponding pressure differential between the chambers of the
converter lockup clutch.
[0329] The block 101a denotes the inverse function of the hydraulic
setting member portion in that the corresponding desired current is
calculated from the desired pressure. Such portion of the setting
member includes a feedback of the measured actual pressure in the
form of a pressure adaption which is denoted by the block 102a.
This pressure adaption 102a supplies the corrected desired current.
The second part 101b of the inverse transfer function 101 of the
setting member constitutes the electrical portion which calculates
the corresponding scanning ratio from the corrected desired
current. A PID regulating algorithm is used to this end. The input
value I.sub.Soll-R for the inverse transfer behavior of the
electrical setting member portion is calculated with the PID
regulator from the control deviation
I.sub.Soll-Korr=.sup.-I.sub.Ist (I.sub.Ist is measured past the
valve winding).
[0330] The numbering of individual blocks which is selected in FIG.
9 corresponds essentially to the numbering of the individual blocks
in FIG. 7. In this way, the individual function blocks of the
special electrohydraulic embodiment shown in FIG. 9 can be related
to those of the generic design according to FIG. 7.
[0331] The individual reference characters shown in FIG. 9 denote
the following:
[0332] DP.sub.Soll=110=desired pressure differential at the lockup
or converter lockup clutch. It corresponds to the differential
between the pressures prevailing in the chambers at opposite sides
of the piston of the lockup clutch.
[0333] DP.sub.Ist111=actual pressure differential between the two
chambers of the converter lockup clutch.
[0334] P.sub.Nach=, pressure downstream of the lockup or converter
lockup clutch.
[0335] I.sub.Soll=113=desired current for the electrohydraulic
valve.
[0336] .DELTA.114=RPM differential between the pump and the turbine
of the converter; thus, .DELTA.N=N pump-N turbine.
[0337] The parameters of the vehicle 115 indicated in FIG. 9 in
front of the block 76 are indicative of the slip in the lockup
clutch or in the converter.
[0338] As can be seen in FIG. 9, the RPM differential .DELTA.N=N
pump-N turbine does not represent any regulating value as is the
case in connection with conventional slip regulations. In
accordance with the novel torque regulation or control, this RPM
differential .DELTA.N is used as a condition value of the path to
be controlled to monitor possible torque deviations which, in turn,
have a correcting backlash effect upon the regulation in the
adaption through corresponding junctions. The ascertained torque
values can be stored, e.g., in the manner of a simultaneously
moving time window, for a certain period of time in order to detect
the proportions of deviations at the clutch and at the engine. This
takes place in a system adaption shown at 116.
[0339] The control or regulation according to the invention
exhibits the additional advantage that the adaption of the
breakdown proportions of the driving torque can also take place
with the lockup or converter lockup clutch fully disengaged, i.e.,
with K.sub.ME=0. To this end, the nominal driving torque is
compared with the torque acting upon the converter; this takes
place at the junction 63 shown in FIG. 7 or at the process step of
FIGS. 7 and 9. Through this adaption, and in anticipation of a
later engagement of the lockup clutch, possible deviations of
driving torque are considered already in the disengaged condition
of the lockup clutch. To this end, the torque being applied to the
converter is determined in the system adaption 116 or 64.
Preferably, the converter characteristic field is stored or
memorized in this system adaption for such purpose. By determining
the RPM differential between the turbine and the pump of the
converter, it is thus possible to determine the applied torque.
Such converter torque is then compared with the nominal input
torque of the engine or driving aggregate. This input torque can be
derived from a stationary characteristic field of the engine which
is memorized in the block 61 of FIGS. 7 and 9, namely as a result
of the measured condition values such as especially the engine RPM,
load lever position, fuel consumption, injection amount or
injection time, etc. The RPM differential between the turbine and
the pump of the torque converter can be determined in the block
76.
[0340] Furthermore, it is possible to determine the converter
torque already in the block 76; the converter characteristic field
is then memorized in the block 76.
[0341] FIG. 10 shows a vehicle 201 with a combustion engine 202
which acts upon a gearbox 204 through a clutch 203 which is self
adjusting or compensates for wear. The gearbox 204 is connected,
through a drive shaft 205, with a driving axle 206 of the vehicle
201. With the self adjusting clutch 203 or with a clutch which
compensates for wear, one distinguishes between an input side 207
which is adjacent the combustion engine 202 and an output side 208
facing the gearbox 204. The engaging and disengaging system for the
clutch 203 is connected with a slave cylinder 210 which is
connected with a master cylinder 211 through a hydraulic conduit
209. A clutch engaging and disengaging system, such as a mechanical
disengaging bearing, can come into contact with the tongues or
prongs of the diaphragm spring in such a way that it determines the
bias of the diaphragm spring upon the pressure plate in a direction
toward the engine and thus the bias upon the friction linings
between the pressure plate and the flywheel. The hydraulic conduit
209 is connected, by the master cylinder 211, with an electric
motor 212 which is confined in a housing together with the master
cylinder 211 to constitute therewith a setting member 213. A clutch
movement detector 214 is mounted in the same housing immediately
adjacent the master cylinder 211. Furthermore, a control apparatus
(not shown in the drawings) is mounted on a circuit board 227 (FIG.
11b) in the setting member housing. This electronic control device
contains the output and also the control electronics and is thus
mounted entirely within the housing of the setting member 213.
[0342] The control apparatus is connected to a throttle valve
sensor 215 which is mounted directly on the combustion engine 202,
with an engine RPM sensor 216, and with a tacho sensor 217 which is
mounted on the driving axle 206. Furthermore, the vehicle 201
comprises a gear shift lever 218 which acts upon the gearbox 204
through a switching linkage. A switching path sensor 219 is
provided on the gear shift lever 218 and is likewise in signal
transmitting connection with the control apparatus.
[0343] The control apparatus provides the electric motor 212 with a
setting value in dependency upon the attached sensor system (214,
215, 216, 217, 219). To this end, a control program is implemented
in the control apparatus, either as hardware or as software.
[0344] The electric motor 212 acts upon the self adjusting clutch
203 through the hydraulic system (209, 210, 211) in dependency upon
the signals from the control apparatus. The mode of operation of
clutches corresponding to the clutch 203 is described in detail in
published German patent applications Nos. 42 39 291, 43 06 505, 42
39 289 and 32 22 677. The disclosures of these publications are
referred to herein as forming part of the disclosure of the present
application. An advantage of a self adjusting clutch 203 is that
the forces which are necessary to operate the clutch are
considerably smaller than in conventional clutches due to the wear
compensating design of the self adjusting clutch. Thus, the
electric motor 212 can be dimensioned to consume and transmit
smaller amounts of power and, therefore, the apparatus can employ a
more compact setting member 213. The setting member 213 of FIG. 10
is not drawn to scale as compared with the other components of the
vehicle 201.
[0345] The setting member 213 will be explained in greater detail
with reference to FIGS. 11a, 11b and 12a, 12b. The electric motor
212, preferably a direct-current motor, acts through an engine
shaft 220 upon a worm which meshes with a segment gear 222. The
segment gear 222 carries a pusher crank which is operatively
connected with a piston 225 of the master cylinder 211 by a piston
rod 224. A snifting member 250 with a snifting bore or hole 251 is
provided on the master cylinder 211 to compensate for thermal
influences upon the hydraulic fluid.
[0346] The electric motor 212, such as a direct-current motor,
exerts a pull or push upon thepiston 225 of the hydraulic master
cylinder 211 through the gearbox which can be self locking. Such
forces are transmitted to the clutch 203 through the hydraulic
conduit 209. In this manner, the clutch 203 is engaged or
disengaged in a controlled manner.
[0347] Since the parallel axes of the master cylinder 211 and the
engine shaft 220 are located in different planes, i.e., they are
offset, the setting member 213 occupies even less room.
[0348] A servo spring 226 is provided in the piston 225 or within
the master cylinder housing 221 concentrically with the master
cylinder 211. This servo spring 226 supports the electric motor 212
during disengagement of the clutch. The spring 226 is tensioned, in
that its bias is overcome, during engagement of the clutch.
[0349] The cooperation between the electric motor 212 and the
spring 226 will be explained with reference to the diagram of FIG.
13. The progress of forces is entered over the clutch movement. The
solid line 237 denotes the force which is supplied by the electric
motor 212 during engagement and disengagement of the clutch 203.
The upper part of this line denotes the force path during
disengagement and the lower part during engagement. Such progress
of force indicates that the disengagement necessitates the
application of greater forces than the engagement. The dot-dash
line 239 is the characteristic curve of the servo spring 226. The
broken line 238 denotes the cooperation of forces of the spring 226
and the electric motor 212.
[0350] The overall force 238 to be applied by the electric motor
212 is greatly reduced, as shown by the displacement of the broken
force line 228 in the direction of smaller forces. Owing to the
supporting action of the properly selected servo spring 226, the
characteristic curve of the electric motor or the diaphragm spring
is shifted in the negative direction and the maximum values
observable in FIG. 13 in the positive and in the negative
directions of the broken line are approximately equal. Due to such
supporting action of the servo spring 226, it is possible to reduce
the dimensions of the electric motor 212 in comparison with the
dimensioning without the assistance from the servo spring 226. The
assistance by the servo spring in this way presupposes that the
electric motor is used in the pull and push directions.
[0351] In FIG. 12a, the servo spring 226 is mounted in the actor
housing wherein it is installed between two abutments 227a, 227b.
The abutment 227a is spring biased against a spring ring 228 which
is connected to the piston rod, and the abutment 227b bears against
a portion of the actor housing. The gearbox is protected against
contamination by a rubber membrane 229 which is adjacent the
abutment 227a. Furthermore, the housing is provided with an
aeration or ventilation bore 230 which allows drainage in the event
of the escape of hydraulic fluid.
[0352] The carrying out of the control or regulation method which
can be implemented with the control apparatus to regulate the
torque in the torque transmission system, such as a friction
clutch, is shown in simplified form in FIG. 14. The regulating
method is stored as a software program, for example, in an
eight-bit processor of the control apparatus. This regulating
method can be used for example, to control the operation of
212.
[0353] The input torque M.sub.Mot of the engine 202 is ascertained
with assistance from the throttle valve sensor 215 and the engine
RPM sensor 216, and is made available to the control program as an
input value. The engine RPM sensor 216 detects an engine RPM N1,
and the tacho sensor 217 registers an RPM of the driving axle 206;
the additional input values are also transmitted to the control
program. A gearbox input RPM N2 is calculated based on the RPM of
the driving axle 206. The difference between the rotational speeds
N1, N2 is designated a slip RPM. The slip RPM is determined
analytically within the control program and is monitored in order
to ascertain whether or not it exceeds a threshold value of the
slip. The rise of the slip beyond the threshold value is detected
as a slip phase S. Such slip phase S prevails until the actual slip
decreases below the threshold value.
[0354] The clutch torque M.sub.K is calculated by means of a
correction value M.sub.Korr in accordance with the equation
M.sub.K=M.sub.mot-M.sub.- korr.
[0355] The correction value M.sub.korr is a torque which is
increased incrementally with the computer cycle and is reduced
during the intervals detected as slip phases S in accordance with
the control program. This method ensures that the clutch 203 is
continuously close to a slip limit R. The slip limit R is the
instant when the engine RPM Nl begins to exceed the gearbox input
RPM N2. This happens exactly when the torque being applied at the
input side is greater than the then transmissible clutch torque.
Such method is satisfactory also when the input torque is not
constant.
[0356] The characteristic line field which is illustrated in FIG.
15 is evaluated prior to transmission of the setting value to the
setting member, especially in a torque transmission system such as
a friction clutch.
[0357] The region of possible positioning of the setting member,
i.e., the range of transmissible clutch torque, is measured along
the abscissa. This region is divided into partial zones 240 one of
which is highlighted by hatching. This highlighted area or zone 240
denotes that clutch torque which can be transmitted between 100 and
140 Nm. As long as the transmissible clutch torque which has been
calculated according to the regulating method of the invention is
within this partial zone, a permissible value of 140 Nm is assigned
to the setting member. The procedure is analogous within other
partial zones 240.
[0358] In accordance with this method, the number of setting
movements of the setting member is further reduced. The setting
movement, namely from one plateau to another plateau, is limited to
a certain magnitude. This design of the characteristic field
regarding the setting movement can be such that the number of
blocks or zones 240 can vary in dependency upon the nature of
application. In general, these undertakings prolong the life
expectancy and reduce the energy requirements of the actuatorism of
the torque transmission system.
[0359] FIGS. 15a to 15e show a selection of setting member
positions to be assumed in accordance with the regulating method
for a desired clutch torque.
[0360] By automating the actuation of the clutch, it is necessary
to provide an actor to facilitate the conversion of control signals
into disengaging or engaging steps or movements of the clutch. An
adaptive control of the setting behavior of the actor can be
carried out in such a way that one achieves a torque matching or
torque follow up. The reliance upon torque matching is advantageous
because it can ensure that the setting member not only carries out
the engagement and disengagement during gear shifting and starting
but also sets the clutch contact pressure during each stage of the
driving operation so that the transmissible clutch torque always
corresponds to a desired clutch torque reflecting the driving
conditions or the operating point, or a corresponding desired
contact pressure or reduced contact pressure in comparison with the
clutch torque can be established. This ensures that, during gear
shifting, the setting device or setter need not move from the fully
engaged position and through the entire setting range in order to
disengage the clutch since, as a result of torque matching or
follow up, the setting device already occupies a position which
corresponds to the actually selected torque plus a desired offset
value. In this manner, the demands upon the dynamic behavior of the
system, especially of the actor, can be reduced to ensure a maximum
adjustment speed since, as a rule, shorter adjustment distances
must be covered.
[0361] A dynamic torque matching or follow up designed in the above
outlined manner renders it necessary that the actor and the
electric motor remain in operation during the entire period of
operation or driving time in order to be able to carry out a quasi
instantaneous adjustment according to dynamic changes of the actual
torque.
[0362] With a regulating or control method which ensures a
continuous torque matching, an electric motor must constantly copy
for example variations of the transmissible torque. A possibility
of using the electric motor only when required can lead to a
copying of the clutch torque which is realized in stages or in a
stepwise fashion.
[0363] The regulating or control method can ensure at all times
that the clutch can transmit a desired clutch torque as determined
at each successive interval of time. Copying of the clutch torque
entails that one can tolerate slight overpressures .DELTA..sub.m
within a certain scatter band. This, in turn, means that follow-up
movements of and thus the load upon the setting member can be
reduced. The curve 241 of FIG. 15a denotes the calculated desired
clutch torque wherein the function 242 corresponds to the desired
clutch torque plus a certain scatter band. The values of the
scatter band of the function 242 are derived from the step height
.DELTA.M and from the requirement that the selected clutch torque
may not exceed the calculated clutch torque as well as that a
change of the selected clutch torque is carried out only if the
change exceeds a threshold value.
[0364] FIG. 15b shows by way of example a mode of operation in
accordance with a control or regulating method wherein the desired
clutch torque is adjusted above a threshold value 243. When the
value of the desired clutch torque is less than or equal to the
threshold value, the selected clutch torque assumes a value which
can be the same as or different from the threshold value. By fixing
the scatter band and a corresponding starting up, a definite
excessive contact pressure develops within certain operating ranges
which, however, leads to a timely shortened action of the setter
and, hence, the load upon the setter is also reduced. The method
according to FIG. 15b shows that a minimum clutch torque is
selected at low desired clutch torques and thus the setter
movements which are associated with a stressing of the setting
system can be reduced. For example, the minimum clutch torque 243
can be dependent upon the operating point, e.g. , upon the
transmission ratio, the setting of the gearbox, the engine RPM, the
position of the accelerator pedal, or upon a brake signal. FIG. 15c
shows a dependency of the minimum clutch torque as a function of
the operating point; the stepped curve 244 conforms to the dynamic
behavior of the operating point and the copied clutch torque 241 is
adapted accordingly.
[0365] The method which is shown in FIG. 15d leads to a minimum
clutch torque which is dependent upon the operating point plus a
behavior combined according to the method of stepwise matching in
relation to a scatter band.
[0366] FIG. 15e indicates a behavior of the clutch torque as
determined by a minimum clutch torque 243 which, however, cannot be
illustrated in areas with constant value because it is a function
of the time. This minimum torque is caused to conform through a
step function 245 and, when the desired clutch torque 241 exceeds
the minimum clutch torque, a quasi instantaneous copying of the
torque is carried out without undertaking an adaption in relation
to a scatter band.
[0367] FIG. 16 shows the circuit diagram of a conventional
H-circuit. One distinguishes between individual shift lanes 250 and
a selection path 251 for the selection of individual shift lanes
250. The path covered by the gear lever 218 within the shift lanes
250 is designated as a shift path 252. The directions of movement
along the shift path 252 and the selection path 251 are indicated
in FIG. 16 by corresponding arrows.
[0368] The position of the shift lever 218 can be monitored by two
potentiometers, especially linear potentiometers. One of the
potentiometers monitors the shift path, and the other potentiometer
monitors the selection path. In order to carry out the monitoring
operation which can likewise be implemented in the control
apparatus, one monitors and evaluates the shift path and/or the
selection path. The mode of practicing the monitoring method will
be explained with reference to FIG. 17. In FIG. 17, the signal
paths which are relevant for the monitoring method are shown in the
form of a diagram as a function of the time t. The coordinate
inscriptions correspond to any desired subdivision of the monitored
shift path 252 within a computer. More specifically, a gear lever
signal 260 is plotted as a function of time t and such signal is
directly proportional to the monitored shift path 252.
[0369] The plotted path of the gear lever signal 260 corresponds to
a typical gear shifting procedure. The gear lever 218 remains in
its position approximately up to the time t denoted here as 8.3
seconds. Up to such time, the gear lever signal 260 exhibits only
the vibrations which are typical of a driving operation. Such
vibrations typically develop in the torque transmission system and
are additionally caused to develop from the outside, for example,
due to unevenness of the road surface. After elapse of the time
interval of 8.3 seconds, the gear lever 218 is moved along the
shift lane 250 so that the intensity of the gear lever signal 260
increases from an approximate value of 200 increments to about 480
increments. This value remains constant for a certain interval of
time and corresponds either to a holding still by the user or to
the interval of time which is required to complete the advancement
along a selection path 251. Finally, a gear is engaged. The value
of the gear lever signal 260 increases to about 580 increments and
remains substantially constant for a certain period of time. This
corresponds to the time interval which is required for the
synchronization of the gearbox ratio to be engaged. The intensity
of the gear lever signal then rises to a value which corresponds to
the newly selected and engaged gear ratio. In addition, the gear
lever signal 260 is subjected to a digital or analog filtering with
an adjustable time delay so that one obtains a linearized filter
signal 261 following the gear lever signal 260. The filter signal
261 is acted upon by a constant value and by an offset signal which
is a function of the input torque of the driving unit 202. The thus
obtained sum signal is shown in the diagram of FIG. 17 as a
comparison signal 262.
[0370] The switching intent detection is carried out in dependency
upon the monitoring of the time dependencies of the progresses of
the gear lever signal 260 and the comparison signal 262. As soon as
the path of the gear lever signal 260 crosses the path of the
comparison signal 262, a switching intention counter is set to zero
and the monitoring of the time dependencies started. This point of
time is shown in the diagram, as at t.sub.1. The count of the
switching intention counter thereupon progresses in dependency upon
a computer cycle toward a predetermined maximum point of the
counting value. In this manner, one provides an accurately
determined control time interval during which the detected
switching intent is verified. During such interval, the counter can
be stopped and reset to zero at any time in response to the
application of control signals. Such control signals can be
transmitted by an attached system of sensors. These sensors monitor
further influence values, such as the input torque, the attached
load or the further progress of movement of the gear lever 218. As
soon as this sensor system picks up measured values which
contradict the detected switching intention, a control signal is
transmitted to the switching intention counter. In this manner, the
torque transmission system is protected by the aforedescribed
monitoring method against faulty releases. A switching intention
signal is transmitted to the next following operating system only
when the switching intention counter reaches the predetermined
count prior to transmission thereto of a control signal.
[0371] The gear lever signal 260 and the filter signal 261
generated thereby are again shown drawn to a different scale. In
order to generate the comparison signal 262, the intensity of the
filter signal 261 is increased by a constant value and by an offset
signal which is dependent upon the input torque. The constant value
must be sufficiently large to ensure that the path of upon the
input torque. The constant value must be sufficiently large to
ensure that the path of the gear lever signal 260 does not
intersect the path of the comparison signal 262, without the
existence of a switching intention, as a result of typical
operational vibrations of the gear lever 218 during operation of
the vehicle lever signal 260 because this could lead to undesired
releases. This must apply even if the input torque, for example, as
a result of an interruption of fuel admission, has become zero and
thus the offset signal has become zero. The time point for the
withdrawal of the driving torque is designated as t.sub.2 (FIG.
18). Thereafter, the comparison signal 262 corresponds to an
intermediate comparison signal 263 which is obtained additionally
only from the filter signal 261 and a constant value. In operation,
the constant value preferably conforms to the elasticity of the
gear shift linkage and thus to the potential extent of vibration,
such as the vibration amplitude of the gear lever.
[0372] FIG. 19 shows the progress of a gear lever signal 260 in the
course of an extremely slow gear changing operation. When the gear
shifting is carried out with such pronounced delay, there exists
the danger that the gear lever signal will not intersect the
comparison signal. This would entail that the existing shift
intention would not be reliably recognized. For this reason, the
monitoring method is additionally expanded by the illustrated
monitoring of the gear lever change, i.e., of a change of the gear
lever path as a function of time. Thus, the change of the gear
lever signal 260 is monitored in that the path change ascertained
in a time window in a predetermined zone outside of the space which
the non-operated gear lever occupies is checked to ascertain
whether the intensity of the signal has decreased below a threshold
value. If the intensity of the gear lever signal has decreased
below such threshold value, this is presumed to denote a switching
intention independently of the progress of the comparison signal
262. In the illustrated case, the shifting operation begins a time
point t.sub.3. The monitoring area of the gear lever path extends
from a first path s.sub.1 to a second path s.sub.2. The monitoring
time window extends from a time point t.sub.4 to a time point
t.sub.5. The path change established during the time interval
.DELTA.t between the time points t.sub.4 and t.sub.5 within an area
s is below a memorized threshold value and, accordingly, a
switching intention signal is transmitted to the following
operating systems.
[0373] The mode of operation of the switching intention counter
will be explained with reference to FIG. 20. In the embodiment
which is shown in FIG. 20, the gear lever signal 260 reaches a peak
at the time point t.sub.5. This peak causes a crossing of the gear
lever signal 260 with the comparison signal 262. Thus, the
switching intention counter is started at the time point t.sub.5.
In addition, a timer is started simultaneously with the switching
intention counter. The timer receives a signal when the peak of the
gear lever signal path 260 decreases which results in a renewed
crossing of the gear lever signal 260 with the comparison signal
262. The timer is thereby arrested and the then indicated time is
compared with a memorized minimum time interval. In the present
case, it is assumed that the time detected by the timer is shorter
than the memorized time interval. As a consequence, a control
signal is transmitted to the switching intention counter. The
switching intention counter is thereby arrested and is reset to
zero. Thus, a switching intention has been recognized through the
peak at the time point t.sub.5 and, consequently, the switching
intention counter has been started but a transmission of the
switching intention signal to the following operating systems has
not taken place since a control signal was detected within the
control time interval between the starting of the switching
intention counter and the reaching of the maximum count. In
contrast to the above, the switching intention actually existing at
the time point t.sub.6 is recognized and evaluated in the described
way. A switching intention signal is transmitted to the following
operating systems shortly after the time point t.sub.6.
[0374] FIG. 21 is a diagrammatic illustration of a clutch operating
system 300 for a motor vehicle. The total path which is being
considered is established essentially by the partial system
including the engine, a setting member 301 (such as for example an
electric setter), a connecting transmission system 302 and a torque
transmission system 303 (such as a clutch).
[0375] The setting member 301 can constitute a mechanical or
hydraulic or pneumatic setting member. The connecting system which
is mounted between the setting member 301 and the torque
transmission system 302 (such as a clutch) can be a linkage in the
widest sense or a hydraulic connecting unit. One embodiment of a
hydraulic unit is illustrated in FIG. 21 wherein a master cylinder
304 is connected to a slave cylinder 306 by a hydraulic conduit
305.
[0376] A power amplifying device 307 can be mounted in the master
cylinder 304 and/or in the slave cylinder 306. For example, the
power amplifying device 307 can be a spring or a diaphragm
spring.
[0377] The torque transmission system 303, such as a clutch, can be
a friction clutch and/or a self adjusting clutch or a clutch such
as a SAC clutch which automatically compensates or adjusts for
wear.
[0378] The regulating or control method with path adaption of the
clutch operating system is based on that, as a prerequisite for a
successful adaption, the individual parts of the system are
examined for possible changes.
[0379] In order to ensure the success of such adaption, it must
first be understood which problems or which effects can play a role
in or can affect the individual parts of the system and/or can
influence an adaption. For this reason, the components mentioned
above will be briefly dealt with again and anticipated sources of
defects and problem areas will be pointed out.
[0380] The engine torque is generally determined or calculated from
a characteristic field on the basis of the engine RPM and the
subatmospheric pressure in the suction intake manifold (or, as an
alternative, the angle of the throttle valve). In the same way, the
solution of the same system or systems can be used to determine the
engine torque. Errors in the characteristic field and/or when
determining the subatmospheric pressure in the suction intake
manifold can result in deviations from the actual torque.
Furthermore, the torque takeup of the auxiliary aggregates is not
known. To this extent, there develops a further departure from an
accurate determination of the actual engine torque. Still further,
special features of the engine control (idling regulator, knocking
control, coasting switch off) can likewise entail faulty
conclusions in connection with the determination of engine torque.
An adaption of these special features of the engine control can be
taken into consideration in connection with an adaption strategy in
order to ensure an accurate determination of the engine torque. The
electronic systems which are provided, for example, to turn off the
coasting render it possible to process, for example, signals which
in relation to terminating a coasting operation transmit a signal
to the electronic clutch management in order to ensure as accurate
determination of engine torque as possible.
[0381] The setting member 301 can constitute an electric setter. In
this system, a selection of a desired path, for example, of the
clutch pressure plate, is converted through a path control or
regulation. For a regulation, the knowledge of the actual path is
absolutely necessary in order to be able to regulate in the system
without permanent control deviation. The actual path can be
measured and is thus available for further calculations. On the
basis of a theoretical clutch characteristic line, it is possible
to calculate from the actual path a theoretical actual torque
M.sub.KIstth (thus, it is not necessary to use the desired path and
to approximate time behavior of the controls through a model).
[0382] A further possibility of obtaining an additional auxiliary
value for the adaption is to calculate a theoretical push force by
way of the tension and resistance. By means of this push force, it
is possible to calculate a second theoretical torque M.sub.Kist2.
Any changing of the push force must reflect changes of the clutch
torque. If this is not the case, then corresponding corrections can
be carried out. A further possibility resides in the utilization of
general forces for the transmission of torque in that the relevant
actual value of the forces can be compared with the corresponding
value of the actual torque in order to determine whether
correspondence of the numerical value is established in the engaged
and/or disengaged condition of the clutch.
[0383] If a hydraulic system is used as a connection between the
setting member and the clutch, the temperature of the system and
the viscosity of the torque transmitting hydraulic fluid medium
play a decisive role. Furthermore, the length of the conduits and
the cross sections of the pipes can be taken into consideration
since, in the event of temperature changes and temperature
differences, these parameters are subject to variation and may lead
to inaccuracies. For example, the connecting conduit between the
slave cylinder and the master cylinder can be subjected to
expansion, such as a change of length or a change of the cross
section each of which would be indicative of a position other than
the actual position of the clutch.
[0384] The torque transmission system can be a clutch or a self
adjusting clutch. The so-called influences are to be ascertained as
a change of the contact pressure forces or a change of the friction
value. The changes which develop in relation to the contact
pressure forces will be described hereinbelow.
[0385] An adaption can also involve a change of the friction value
over the energy input and a change of the friction radius as a
change of the friction energy input.
[0386] An adaption strategy can provide that the clutch torque is
adapted only from a certain minimum value, see FIG. 22.
[0387] An adaption of the overall setting system of the clutch
actuator unit (comprising the engine, the setting member, a
hydraulic system and a clutch) provides for an identification of
the contributions of the individual partial systems. Each partial
system is analyzed and the possible sources of defects can be
detected and the consequences of these possible sources of defects
can be estimated and eliminated or reduced. It can also be
ascertained which sources of defects are important and which can be
disregarded.
[0388] The adaption can provide for additive shares which are taken
into account. The additive shares are intended to encompass those
shares which are independent of the absolute value or the absolute
level of the torque. For example, the additive share can be taken
up e.g., by auxiliary aggregates (consumers ahead of the clutch).
However, defects of the characteristic field of the engine torque
can also be compensated for through additive shares.
[0389] FIG. 23 illustrates a diagrammatic model or a block circuit
diagram which takes into consideration the additive shares. A block
400 contains the engine with the applied engine torque Man. A block
401 shows the taking into account of the additive shares of e.g.,
secondary aggregates and defects in the characteristic field of the
engine. The correction torque M.sub.Korr to be introduced thereby
is taken into consideration at the junction 402. It applies
that:
M.sub.anKorr=M.sub.an-M.sub.Korr.
[0390] The moment of inertia of the system is considered at the
block 403. This can mean that, for example, only the moment of
inertia of the flywheel or also of the parts of the power train is
taken into consideration. A dynamically corrected torque is formed
at 403 in order to determine the torque being applied by a clutch
404.
[0391] The torque can be corrected or adapted by a multiplicative
share. Sources for the necessity of multiplicative shares are, for
example, the changing friction value, e.g., as a function of the
temperature and aging of springs for the linings with their changed
spring characteristics.
[0392] If the assumed and the actual friction values differ from
each other, the error becomes greater the greater the required
clutch torque.
[0393] A block 406 in the block circuit diagram of FIG. 23 denotes
the vehicle mass.
[0394] An adaption method can be designed in that, in the case of a
consumer adaption, one ensures that the clutch torque
(M.sub.KSoll-Korr) is reduced to such an extent that it leads to
slippage of the clutch. This can be explained in that the value of
M.sub.Korr (correction of the aggregates) is increased according to
the equation
M.sub.KSoll-Korr=K.sub.me*(M.sub.an-M.sub.Korr)+M.sub.sicher
[0395] until the development of a slip. During such slip phase, the
clutch torque can be increased again according to a predetermined
always accurately defined function (e.g., ramp-like lowering of
M.sub.Korr) until the slip is reduced. Based on such behavior, an
evaluation of the consumer can take place; the evaluation can be
carried out each time or only once or several times per slip
cycle.
[0396] In an ideal case when the actual characteristic curve of the
clutch corresponds to the assumed characteristic line, the value of
M.sub.Korr contains that proportion of the torque which the
consumers branch off or require. On the basis of such estimation or
calculation, and assuming the presence of a defect in the engine
torque, it is possible to furnish information concerning the
friction value.
[0397] Since there are no negative consumers, negatively adapted
consumers can be adapted or interpreted as a friction value which
is too low. Furthermore, the torque takeup of the individual
consumers is restricted, and the corresponding absolute level need
not be known at all. Thus, exceeding a threshold value can be
interpreted as a friction value which is excessive.
[0398] Based on an appropriate selection, fixing of an upper
barrier or threshold value renders it possible to avoid the
selection of a value which is excessive so that the detection of a
change of the friction value would be too late. It can likewise be
avoided that, when the threshold value is too low, the secondary
consumers would be interpreted as a change of the friction
value.
[0399] It can be advantageous if the adaption is carried out only
in the course of a pulling operation; in such event, the adaption
should be carried out above a minimum torque.
[0400] Such simple adaption method (see also FIG. 14) entails that
a splitting of the adaption model into an additive portion
(consumers, etc.) and a multiplicative portion takes place only by
fixing or determining the limits. Within the limits, the portion is
assumed to be additive, and outside of the limits the portion is
assumed to be multiplicative defects of other causes, such as for
example of the engine torque.
[0401] In this manner, an error or a breakdown of the engine torque
is added to the consumers or to the characteristic curve of the
clutch.
[0402] FIG. 24 provides an example of an embodiment, namely an
estimate or appraisal of the additive and multiplicative portions
in the slip phases with different load conditions.
[0403] The curve 450 denotes the timely progress of the corrected
clutch torque. The curve 451 indicates the timely progress of the
engine RPM n.sub.mot, and the curve 452 the timely progress of the
gearbox input RPM n.sub.Getr.
[0404] At the onset of the observation time point shown in this
example, the engine RPM 451 is approximately equal to the gearbox
RPM 452. The corrected clutch torque shows a slightly decreasing
time behavior.
[0405] A slip phase takes place during the time interval 453 and
the engine RPM 451 is slightly above the value of the gearbox RPM.
The clutch torque 450 rises after the detection of the slip phase.
At the time instant 456, the engine RPM 451 reaches a relative
maximum and the increase of the clutch torque permits the engine
RPM to drop again.
[0406] A so-called tip-in takes place at the beginning of the time
period 454, i.e., an increase of the engine RPM is introduced for a
short interval of time. No adaption takes place during this phase
and the gearbox RPM follows the engine RPM 451 with a time
delay.
[0407] The time period 455 involves a slip phase, the same as the
time period 453.
[0408] Since the consumer adaption is or can always be close to the
slip limit, there exists the additional possibility of evaluating
those slip phases at which the overall contact pressure changes or
has changed, i.e., the desired torques at the clutch or at the
torque transmission system lie at different levels, for example, by
showing different engine torques and/or load conditions. A
prerequisite for this is that the actual consumer has not changed,
i.e., too long a time span between the slip phases is not a very
favorable indication.
[0409] If the consumer value, does not change at different load
conditions, such as in the slip phases 453 and 455, it can be taken
for granted that the assumed and/or determined and/or calculated
friction value corresponds to the actual friction value of the
clutch.
[0410] In such a case, the friction value can be corrected or a
correction can be carried out.
[0411] In this embodiment, it is advantageous to carry out a
division into an additive to and a multiplicative portion.
[0412] In the event of a consumer change during the interval of
adaption, a separation of a friction value change and a consumer
change cannot be correctly carried out; however, this can be
compensated for to a large extent through an increased frequency of
the adaption procedure.
[0413] Furthermore, it is possible to carry out adaption during the
constant phase after load changes, and such adaption can be
combined with other adaption strategies as a result of potentially
long intervals of time.
[0414] It is also possible to carry out an adaption of the
multiplicative portion in dynamic areas or cases, such as e.g. a
tip-in and/or during starting. In the event of a slip, it applies
that 1 M an - M korr - ist theo * M KSoll korr = J * d dt .
[0415] By means of this equation, it is possible to detect the
unknown values, .mu.ist and .mu.theo being the actual and
theoretical friction values.
[0416] This adoption method will be explained in greater, detail
with reference to FIG. 25 which shows the timely behavior of the
applied torque 500, of the actual clutch torque 502, engine RPM
501, J*d.omega./dt 503, the gearbox RPM 504 and the corrected
desired clutch torque 505.
[0417] In the phase 506 in which the applied engine torque 500 is
constant, a change of J*d.omega./dt 503 must be correlated with a
change of the corrected desired clutch torque when the selected
clutch torque 505 does not change. However, such condition is
fulfilled in most situations since, as a rule, the consumers hardly
change on short notice. If these alterations are not correlated,
i.e., if a change of the corrected desired clutch torque 505 does
not entail a change of J*d.omega./dt (503), the friction value must
be corrected accordingly. If the change of the corrected desired
clutch torque 505 exceeds that of 503, the theoretical friction
value must be lowered because the actual friction value is less
than the assumed value. If the reverse happens, it is necessary to
proceed accordingly.
[0418] This method renders it possible to directly calculate or
determine the friction value. It is therefore possible to calculate
the level of the value of the secondary consumers at a point of
time when the engine RPM gradient is zero, such as e.g. at the
positions 507, because the engine torque is known. At such time, it
applies that: 2 M korr = M an - ist theo * M Ksoll korr
[0419] Since the setting member lies between the calculated desired
torque .sup.MKsollkorr 505 and the actual torque of the clutch 502,
and since as a rule the setting behavior is not to be disregarded,
it is possible to carry out a modelling of the setting member in
order to further enhance the quality of adaption in dynamic cases.
If the setting device of an electronic clutch management system is
operated by an electric motor, it is possible to calculate, based
on a path measurement, for example, in the master cylinder, a
theoretical actual torque 502 from the measured actual path and a
characteristic line. This can be used in lieu of the desired torque
and shall be designated as MK.sub.ist 502 . In this manner, one
circumvents the dynamic proportion which arises through the path
regulation. The adaption method is particularly advantageous under
all driving conditions when a slip occurs. It is likewise
advantageous that a division into a multiplicative and an additive
portion can take place.
[0420] A further possibility for adaption offers the identification
of the multiplicative portion through the evaluation of starting
speeds. This simple possibility of identifying the additive and
multiplicative portions consists in the evaluation of a starting
procedure. At the point of time when the engine is idling at an
idling speed, the driver has not caused the admission of any fuel
and the torques being applied by the engine are used to satisfy the
needs of the engine and to compensate for the auxiliary aggregates.
Therefore, the value of the engine torque which is assumed to exist
in such situation can be assumed as the reference or starting point
for the value of the corrected torque. During starting, when the
driver steps on the gas pedal, the reached engine RPM is evaluated
at a certain point of time. The engine RPM is related to the
applied clutch torque which is the actual engine torque minus the
engine torque shortly prior to the admission of fuel. It is
possible to resort to a table in order to compare whether the
engine RPM pertaining to the applied engine torque corresponds to
the actual engine RPM. In the case of larger deviations, a change
of the friction value exists and the friction value stored in the
control computer can then be corrected accordingly.
[0421] FIG. 26 shows the applied engine torque 510 and the engine
RPM 511 as well as the gearbox input RPM 512 as a function of time.
The vehicle is idling prior to a time 517, and the power or torque
takeoff of the auxiliary aggregates is evaluated based on the
values in the range 513. During the interval following the time
point 518 which is fixed after an acceleration phase, a desired
engine RPM can be determined from the value of the applied engine
torque and this desired RPM can be compared with the actual value
511 of the engine RPM and thus an estimation can be made of the
friction value. This procedure allows a division into a
multiplicative and an additive portion. No effects can be detected
in the case of a dynamic change of the setting member. The adaption
according to this method is characterized in that it is only
possible when starting and a defect of the engine torque signal can
influence the adaption.
[0422] A further possible method of adaption can consist in that
the identification of the entire characteristic curve is carried
out using point-like supporting spots. This possibility, for
systems with a detectable setting value, such as the position of
the disengaging system or the disengagement path, can
advantageously be applied for the calculation if at the beginning
of a dynamic adaption the adaptive part, the consumer torques
and/or aggregate losses are known at least approximately. A
calculation of the offset signal in the case of unknown consumer
torques and aggregate losses could also be carried out by
undertaking the determination through numerical processes.
[0423] In order to identify the characteristic curve, one could
compare, at certain path points or supporting points of the
characteristic curve, the corresponding calculated theoretical
clutch torque 520 (FIG. 27) with that based on the characteristic
clutch curve and the actual path 521. In the event of a departure,
the supporting spots would then be corrected incrementally, and it
then applies that:
.sup.Mkupplungtheo=.sup.Man-.sup.Mkorr-J*d.omega./dt.
[0424] FIG. 27 shows a change of the actual distance covered by the
setting member on the basis of the actual value 522 in a time
window 523 and the gearbox RPM 525. By using the supporting spots
526, it is possible to determine from the actual path and from the
knowledge of the characteristic curve of the torque transmission
system the corresponding calculated clutch torque 520 which can be
compared with the actual clutch torque. FIG. 27 shows these values
as a function of time, the supporting spots 526 being adapted to be
defined by using the information regarding the location of the path
of the setting member, and the spreading out of individual
supporting spots takes place according to the speed of movement of
the setting member.
[0425] FIG. 28 shows a characteristic clutch curve 530 with
supporting spots 531 at which the clutch torque is determined and
calculated. Furthermore, there is shown the adaption range 532
which need not be fixed for the entire length of the characteristic
clutch curve. It can be advantageous if the torque area is adapted
above a threshold value 533 and an adaption below the threshold
value 533 takes place in order to set a minimum value as proposed,
for example, in FIGS. 15a to 15e. Such adaption can be independent
of the recorded basic path of the characteristic curve. Errors of
the theoretical characteristic curve are compensated for.
[0426] Consequently, the adaption of supporting spots also affects
the operating areas which do not lie on the supporting spots;
however, an extrapolation is necessary in such cases since the
adapted operating points are not or need not necessarily be
touched.
[0427] FIG. 29a shows diagrammatically a power train of a vehicle
with a driving unit 600 and a torque transmission system 601
connected in the power flow at the output side of the driving unit.
An automatic gearbox 610 is installed at the output side of the
torque transmission system, the automatic gearbox being illustrated
diagrammatically as a cone pulley belt contact gearbox without
being restricted thereto. The gearbox can also be an automatic
infinitely adjustable gearbox, such as for example a friction wheel
gearbox or a friction ring gearbox.
[0428] The cone pulley belt contact consists essentially of a
variator which is assembled of two pairs of cone pulley sets 602a,
602b, 603a, 603b, and an endless torque transmitting device such as
an endless belt or chain 604.
[0429] At least one fixed transmission stage 605 is connected at
the output side of the variator of the cone pulley belt gearbox and
acts upon a differential 606.
[0430] FIG. 29b shows the same structural arrangement except for
the position of the torque transmission system 611 which is
installed in the power flow at the output side of the gearbox 610,
such as a variator.
[0431] The contact pressure of the device 604 is selected in such a
way that it does not permit a slip of this device relative to the
sets of cone pulleys. A control system regulates the contact
pressure of the endless device 604 between the pairs of cone
pulleys in order to prevent a slip since slipping can lead locally
to damage and even to destruction of the endless flexible
device.
[0432] In the event of a change of the applied engine torque, an
adaptive regulation can select the transmissible torque in advance
or as a follow-up and a change in the operating point can result in
slipping of the contact or endless flexible device, such as a
chain.
[0433] The pressure of the endless device must take place with an
excess contact pressure in order to avoid, in the event of for
example torsional vibrations in the power train, any slipping as a
result of a temporarily increased adjoining torque.
[0434] The application of contact pressure with the lowest possible
excess contact pressure is desirable since the excess contact
pressure leads to friction losses and thus to a reduction of the
efficiency and an increased fuel consumption. A reduction of the
excess contact pressure can lead to the danger of slippage of the
device 604.
[0435] The aforedescribed fluctuations of the torque which is being
applied and which is to be transmitted by the variator can be
calculated and taken into account by means of a control method
since a dependency upon the operating point can be adapted.
[0436] Furthermore, unforeseen torque surges can take place at the
output side, such as for example if the vehicle passes with turning
tires from a smooth road surface to a non-skid road surface. Under
such circumstances, a torque surge which cannot be calculated in
advance develops at the output side. Neither the timely progress
nor the amplitude of such surges can be calculated in advance.
[0437] In order to protect the variator from such torque surges,
and as shown in FIGS. 29a and 29b, a torque transmission system
601, 611 is mounted in the power train and is controlled in such a
way that the torque which can be transmitted by the torque
transmission system is always less than the torque which can be
transmitted by the variator.
[0438] The application of transmissible torque of the torque
transmission system 601, 611 guarantees at each operating point
that the torque which can be transmitted by the variator is greater
than the torque which can be transmitted by the torque transmission
system. Thus, the torque transmission system constitutes a
torque-guided overload clutch which can be adaptievely controlled
at each operating point. Due to the adaptive control of the torque
transmission system, it is possible to reduce the contact pressure
of the contact means so that the safety reserves for protecting
against slippage of the contact means can be reduced. Thus, the
efficiency of the gearbox can be increased without endangering the
safety of the variator.
[0439] The torque transmission system can be used as a discrete
safety clutch and/or as a turning set clutch and/or as a lockup
clutch in a torque converter or additionally as a clutch for
adjusting the variator.
[0440] The mounting of the torque transmission system at the output
side is particularly advantageous because load surges are detected
earlier at the output side than in an arrangement at the input side
since, in the case of introduction of a torque, the rotary masses
of the variator are still effective.
[0441] An arrangement at the output side exhibits the additional
advantage that, when the vehicle is at a standstill but the engine
is running, the variator rotates and rapid adjustment or an
adjustment from standstill can be carried out more rapidly.
[0442] If the torque transmission system is installed at the output
side, it is necessary when determining and/or when calculating the
applied engine torque to take into account the transmission ratio
of the variator and the losses.
[0443] The invention is not limited to the illustrated and
described embodiments but also encompasses especially those
modifications which can be arrived at through a combination of
features and elements described in connection with the present
invention. Furthermore, individual features and methods described
in connection with the drawings can be considered to constitute
independent inventions.
[0444] The applicants reserve the right to claim, as being
important for the invention, additional features which at the
present time are disclosed only in the specification, especially in
connection with the drawings. Thus, the claims filed with this
application are merely proposed formulations without prejudice to
achieving broader patent protection.
* * * * *