U.S. patent application number 09/846279 was filed with the patent office on 2002-04-18 for apparatus for protecting automatic clutch from overheating.
Invention is credited to Nakashima, Masami.
Application Number | 20020045516 09/846279 |
Document ID | / |
Family ID | 18791771 |
Filed Date | 2002-04-18 |
United States Patent
Application |
20020045516 |
Kind Code |
A1 |
Nakashima, Masami |
April 18, 2002 |
Apparatus for protecting automatic clutch from overheating
Abstract
An apparatus for protecting an automatic clutch from
overheating, capable of holding down the generation of heat in the
clutch even when the condition in which a traveling load at a
vehicle starting time exceeds a predetermined level continues for a
predetermined period of time. The automatic clutch is provided in a
transmission path extending between an internal combustion engine
and a transmission adapted to change a speed represented by an
output from the internal combustion engine. The apparatus comprises
a control unit adapted to receive signal outputs from a pressure
sensor for detecting a pressure in an intake manifold of the
internal combustion engine, a degree of opening of accelerator
sensor for detecting an operation amount of an accelerator and a
vehicle speed sensor for detecting a traveling speed of a vehicle,
to detect a traveling load at a vehicle starting time, and to move
and close the throttle valve to a position of a predetermined set
level by operating a throttle actuator when the condition in which
the traveling load is not lower than a predetermined level and the
traveling speed is not higher than a predetermined value.
Inventors: |
Nakashima, Masami;
(Kobe-shi, JP) |
Correspondence
Address: |
SUGHRUE MION ZINN MACPEAK & SEAS, PLLC
2100 Pennsylvania Avenue, NW
Washington
DC
20037-3213
US
|
Family ID: |
18791771 |
Appl. No.: |
09/846279 |
Filed: |
May 2, 2001 |
Current U.S.
Class: |
477/174 ;
477/175; 477/179; 477/181 |
Current CPC
Class: |
B60W 10/02 20130101;
B60W 2540/10 20130101; B60W 30/1819 20130101; B60W 2510/0638
20130101; B60W 30/18 20130101; B60W 2540/16 20130101; B60W 10/06
20130101; B60W 2510/0671 20130101; B60W 2520/10 20130101; B60W
10/04 20130101 |
Class at
Publication: |
477/174 ;
477/175; 477/179; 477/181 |
International
Class: |
B60K 041/02 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 12, 2000 |
JP |
P 2000-312120 |
Claims
What is claimed is:
1. An apparatus for protecting an automatic clutch from
overheating, wherein the automatic clutch is provided in a power
transmission path between an internal combustion engine mounted on
a vehicle and a transmission adapted to change a speed represented
by an output from the engine, the apparatus comprising: a pressure
sensor adapted to detect a pressure in an intake manifold of the
internal combustion engine, a degree of opening of accelerator
sensor adapted to detect an operation amount of an accelerator, a
vehicle speed sensor adapted to detect a traveling speed of a
vehicle, and a control unit adapted to detect a traveling load of
the vehicle at a vehicle starting time on the basis of the outputs
of the pressure sensor, the degree of opening of accelerator
sensor, and the vehicle speed sensor, and to control a throttle
actuator by which a throttle valve provided in the intake manifold
of the internal combustion engine is operated, wherein the control
unit being adapted to control the throttle valve so that the
throttle valve is moved to and closed in a position of a preset
level when the traveling load is not lower than a predetermined
level with the vehicle speed continuing to be not higher than a
predetermined value for a period of time not shorter than a
predetermined period of time, and thereby protect the automatic
clutch.
2. The apparatus for protecting an automatic clutch from
overheating according to claim 1, wherein, when the condition in
which the traveling load is not lower than the predetermined level
and the vehicle speed is not higher than the predetermined value
continues for the predetermined period of time, the control unit
operates the throttle valve being closed so that an internal
combustion engine attains an idling rotational speed, and the
automatic clutch thereby release to disconnect the internal
combustion engine and the transmission.
3. The apparatus for protecting an automatic clutch from
overheating according to claim 1, wherein an electromagnetic powder
clutch is used as the automatic clutch.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a control apparatus for an
automatic clutch mounted on a vehicle, and more particularly to an
apparatus for protecting the automatic clutch from overheating.
[0003] 2. Description of the Related Art
[0004] In order to engage a clutch when starting an
automatic-clutch-mounted vehicle, the clutch is controlled so that
a smooth engagement thereof can be attained, by gradually
increasing transmission torque of the clutch in accordance with a
rotational speed of an internal combustion engine and a vehicle
speed. During this time, a semi-clutch-engaged condition is
necessarily continued as a clutch engaging force is increased from
an engagement starting time to an engagement completion time. In
this semi-clutch-engaged condition, the clutch is in a slipping
state, so that heat is generated greatly. When a traveling load at
a vehicle starting time is large, the semi-clutch-engaged condition
continuation time increases, and this causes the burning of the
clutch in some cases. In order to prevent such burning of a clutch,
various kinds of measures are taken. For example, the techniques
disclosed in Japanese Laid-Open Patent No. 89795/1994 constitute an
example of these measures.
[0005] According to the techniques disclosed in this publication, a
judgement that a traveling load is large is given when not shorter
than a predetermined period of time has elapsed after the arrival
of the time at which a vehicle started at such a level of
rotational frequency of an internal combustion engine that is in
the vicinity of a stall point is to reach a set vehicle speed, and
a signal the level of which corresponds to the length of the
mentioned time elapsed is outputted so as to increase in a current
setting unit of an electromagnetic clutch the gradient of the
rising characteristics of a clutch current with respect to a
rotational speed of the internal combustion engine. Namely, when a
traveling load is judged large, the engagement of the clutch is
effected earlier by hastening the increasing of a clutch current,
and a slipping period is thereby shortened. This prevents the heat
from doing damage to the clutch.
[0006] Thus, in a related art clutch, the measures for preventing
the burning of the same by hastening the engagement thereof are
taken. Such techniques are effective when the weight onboard is
increased, and when a vehicle runs up a slope. However, an increase
in a traveling load is encountered not only in such a case. Such a
load increase also occurs when a parking brake is not disengaged,
and when the starting of a vehicle is prevented by objects of a
larger height, such as a vehicle stops which the vehicle cannot get
over. When the above-mentioned system having a function of
protecting a vehicle from overheating is put in operation in such
cases, the clutch is controlled so that it is forcibly engaged.
This causes brakes to be overheated, the momentary overheating of
the clutch to occur, or a shock and an engine failure to occur.
SUMMARY OF THE INVENTION
[0007] The present invention has been made in view of the
above-mentioned circumstances, and provides an apparatus for
protecting an automatic clutch from overheating, capable of holding
down the heating of the clutch by minimizing an output from an
internal combustion engine when a traveling load exceeds a
predetermined level with this excessive load condition continuing
for a predetermined period of time, and thereby returning the
operation of the engine to a normal condition without stopping the
engine.
[0008] According to an aspect of the present invention, the
apparatus for protecting an automatic clutch from overheating,
wherein the automatic clutch is provided in a power transmission
path between an internal combustion engine mounted on a vehicle and
a transmission adapted to change a speed represented by an output
from the engine, the apparatus comprising:
[0009] a pressure sensor adapted to detect a pressure in an intake
manifold of the internal combustion engine,
[0010] a degree of opening of accelerator sensor adapted to detect
an operation amount of an accelerator,
[0011] a vehicle speed sensor adapted to detect a traveling speed
of a vehicle, and
[0012] a control unit adapted to detect a traveling load of the
vehicle at a vehicle starting time on the basis of the outputs of
the pressure sensor, the degree of opening of accelerator sensor,
and the vehicle speed sensor, and to control a throttle actuator by
which a throttle valve provided in the intake manifold of the
internal combustion engine is operated,
[0013] wherein the control unit being adapted to control the
throttle valve so that the throttle valve is moved to and closed in
a position of a preset level when the traveling load is not lower
than a predetermined level with the vehicle speed continuing to be
not higher than a predetermined value for a period of time not
shorter than a predetermined period of time, and thereby protect
the automatic clutch.
[0014] On the basis of such a structure, the throttle valve is
closed in a predetermined period of time even when a vehicle is
tried to be started in a case where the starting of the vehicle is
hindered by an unreleased parking brake or a block which the
vehicle cannot get over. This enables the generation of heat
ascribed to the continuation of a slipping condition of the
automatic clutch to be held down, and the burning of the clutch to
be prevented.
[0015] According to another aspect of the present invention, the
apparatus for protecting an automatic clutch from overheating,
wherein, when the condition in which the traveling load is not
lower than the predetermined level and the vehicle speed is not
higher than the predetermined value continues for the predetermined
period of time, the control unit operates the throttle valve being
closed so that an internal combustion engine attains an idling
rotational speed, and the automatic clutch thereby release to
disconnect the internal combustion engine and the transmission.
[0016] On the basis of such a structure, the generation of heat in
and the burning of the automatic clutch can be prevented, and a
subsequent operation can be carried out without accompanying an
engine stall.
[0017] According to still another aspect of the present invention,
the apparatus for protecting an automatic clutch from overheating,
wherein an electromagnetic powder clutch is used as the automatic
clutch.
[0018] On the basis of such a structure, the above-mentioned
operation for protecting the clutch from heating can be carried out
with a high accuracy by simple electric circuit and program.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Preferred embodiments of the present invention will be
described in detail with reference to the following figures,
wherein:
[0020] FIG. 1 is a construction diagram of a system describing one
embodiment of the apparatus for protecting an automatic clutch from
overheating according to the present invention;
[0021] FIG. 2 is a diagram showing function blocks of a control
unit for one embodiment of the apparatus for protecting an
automatic clutch from overheating according to the present
invention;
[0022] FIG. 3 is a flow chart describing an operation of one
embodiment of the apparatus for protecting an automatic clutch from
overheating according to the present invention;
[0023] FIG. 4 is a flow chart describing an operation of one
embodiment of the apparatus for protecting an automatic clutch from
overheating according to the present invention;
[0024] FIG. 5 is a flow chart describing an operation of an another
embodiment of the apparatus for protecting an automatic clutch from
overheating according to the present invention; and
[0025] FIG. 6 is a flow chart describing an operation of the
another embodiment of the apparatus for protecting an automatic
clutch from overheating according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiment 1
[0026] FIGS. 1-4 are drawings for describing the embodiment 1 of
the apparatus for protecting an automatic clutch from overheating
according to the present invention. FIG. 1 is a construction
diagram of a system of a vehicle mounted with an automatic clutch,
FIG. 2 a diagram showing function blocks of a control unit, FIG. 3
a flow chart of an operation for judging a traveling load, and FIG.
4 a flow chart of a throttle control operation. Referring to the
drawings, a reference numeral 1 denotes an internal combustion
engine mounted on a vehicle, 2 an output shaft of the internal
combustion engine 1, which is connected to a drive member 3a of an
electromagnetic clutch 3, 4 an output shaft of the clutch 3, by
which a driven member 3b of the electromagnetic clutch 3 and a
transmission 5 are connected together, 3c an exciting coil of the
electromagnetic clutch 3, 6 a propeller shaft by which the
transmission 5 and a differential gear 7 are connected together,
and 8 a driving wheel of the vehicle. An electromagnetic powder
clutch capable of easily controlling a force for combining the
drive member 3a and driven member 3b together in accordance with a
current value of the exciting coil 3c is used as the
electromagnetic clutch 3.
[0027] A reference numeral 9 denotes a control unit including a
microprocessor 9a, a memory 9b, bus line 9c, an input port 9d and
an output port 9e, and having a function block which will be
described later, and which is shown in FIG. 2. A reference numeral
10 denotes a throttle actuator adapted to control a flow rate of
suction air by regulating a degree of opening of a throttle valve
12 provided in a suction passage 11 of the internal combustion
engine, 13 a vehicle speed sensor adapted to detect a traveling
speed of the vehicle, 14 a degree of opening of accelerator sensor
adapted to detect an amount of operation of the accelerator, 15 a
shift range switch adapted to detect a position of a shift lever,
16 a boost pressure sensor adapted to detect a pressure in an
intake manifold of the internal combustion engine 1, and 17 a
rotational speed sensor adapted to detect a rotational speed of the
internal combustion engine 1. The control unit 9 is adapted to
receive at the input port 9d signal outputs from these sensors, and
output from the output port 9e a driving signal to the throttle
actuator 10 and electromagnetic clutch 3 in accordance with a
program stored in the memory 9b.
[0028] The function blocks of the control unit 18 includes as shown
in FIG. 2 a clutch control device 18, a throttle actuator control
device 19, a traveling load judgement device 20, a clutch
disengagement control device, and a degree of opening of throttle
control device 22.
[0029] The clutch control device 18 is adapted to receive an output
signal from the shift range switch 15, an output signal Vs from the
vehicle speed sensor 13, an output signal Ne from the rotational
speed sensor 17 and an output signal .theta. from the degree of
opening of accelerator sensor 14. The clutch control device 18
judges whether the transmission of torque is required or not on the
basis of information from the shift range switch 15, and judges
that the clutch is in a semi-engaged (slipping) state or in a
directly engaged state on the basis of outputs Vs, Ne, .theta. from
the vehicle speed sensor 13, rotational speed sensor 17 and degree
of opening of accelerator sensor 14 respectively. When a vehicle is
started, transmission torque corresponding to output torque from
the internal combustion engine 1 which is calculated on the basis
of signals from the degree of opening of accelerator sensor 14 and
rotational speed sensor 17 is generated. Therefore, an exciting
current of the exciting coil 3c is controlled on the basis of a
predetermined operation expression. The exciting current is
increased in accordance with an increase in a rotational frequency
of the internal combustion engine 2, and the electromagnetic clutch
3 is thereby smoothly engaged.
[0030] The throttle actuator control device 19 is adapted to
receive an output signal .theta. from the degree of opening of
accelerator sensor 14 and a judgement output from the traveling
load judgement device 20, control the throttle actuator 10 in
accordance with an accelerator pedal stepping amount, regulate the
degree of opening of the throttle valve 12, maintain when releasing
the accelerator the degree of opening of the throttle valve 12 at
an idling level so that a rotational speed of the internal
combustion engine 1 is maintained at a stable idling level, and
control when a signal is inputted from the traveling load judgement
device 20 as will be described later the throttle valve 12 so that
the throttle valve 12 is moved to and closed in a predetermined
position.
[0031] The traveling load judgement device 20 is adapted to receive
an output signal from the shift range switch 15, an output signal
Pb from the boost pressure sensor 16, an output signal Vs from the
vehicle speed sensor 13 and an output signal .theta. from the
degree of opening of accelerator sensor 14. This judgement device
is adapted to judge that a traveling load of a vehicle is large
when the condition having the shift range switch in a traveling
range and a boost pressure at a high level with an increase in a
vehicle speed corresponding to the degree of opening of the
accelerator impossible to attain continues for a predetermined
period of time, and supply a signal of the judgement to the degree
of opening of throttle control device 22. When the degree of
opening becomes smaller than a return judgement level, the
judgement that the traveling load is large is canceled.
[0032] The degree of opening of throttle control device 22 is
adapted to supply a signal to the throttle actuator control device
19 when a signal of judgement that the traveling load is large is
inputted from the traveling load judgement device 20 thereinto,
lower output torque from the internal combustion engine 1 by moving
and closing the throttle valve 12 to and in a position of a
predetermined degree of opening, and thereby hold down the
generation of heat ascribed to the slipping of the electromagnetic
clutch 3.
[0033] A judgement by and actions of the embodiment 1 of the
apparatus for protecting an automatic clutch from overheating
according to the present invention thus constructed are made as
follows. First, a judgement made by the traveling load judgement
device is as shown in the flow chart of FIG. 3. Referring to FIG.
3, a shift position is judged from an output signal from the shift
range switch 15 as to whether the shift position is in a traveling
range or not in Step 301. When the shift position is in neither a
parking range (which will hereinafter be referred to P) nor a
neutral range (which will hereinafter be referred to N), the
operation is advanced to Step 302. In Step 302, the pressure in the
intake manifold is judged on the basis of an output signal Pb from
the boost pressure sensor 16 as to whether the pressure is higher
than a judgement level or not. When this pressure is not lower than
a level at which a load of the engine 1 can be judged high, the
operation is advanced to Step 303.
[0034] In Step 303, a vehicle speed Vs is read from an output from
the vehicle speed sensor 13. When the vehicle speed is lower than a
predetermined level at which a judgement that the vehicle does not
travel can be given, a judgement that there is the possibility that
a traveling load is large is given, and the operation is advanced
to Step 304. In Step 304, 1 is added to a timer T adapted to judge
the condition of the traveling load, and the time of this timer and
judgement time are compared with each other in Step 305. This
routine is repeated for a predetermined period of time. Therefore,
when the condition in which the traveling load is large continues,
the addition in Step 304 keeps being made, and the time of the
timer compared with the judgement time in Step 305 becomes larger
than the judgement time. When the time of the timer exceeds the
judgement time, the operation is advanced to Step 306, and the
traveling load is judged large.
[0035] When the shift range is P or N in Step 301, the operation is
advanced to Step 307, and the timer T is cleared. When the pressure
in the intake manifold is not higher than a predetermined level in
Step 302, or when the vehicle speed is not lower than a
predetermined level in Step 303, the operation is also advanced to
Step 307, and the timer T is cleared. When the timer T is cleared
in Step 307, the operation is advanced to Step 308. When the time
of the timer T is not higher than a judgement level in Step 305,
the operation is also advanced to Step 308. In Step 308, the degree
of opening of the accelerator is judged on the basis of an output
signal .theta. from the degree of opening of accelerator sensor 14.
When the degree of opening of the accelerator is lower than a
preset return judgement level, the judgement that the traveling
load is large is canceled in Step 309. When the degree of opening
of the accelerator is higher than the return judgement level, the
judgement that the traveling load is large is maintained.
[0036] A control routine of the throttle actuator control device 19
is as shown in FIG. 4. First, in Step 401, whether or not the
results of judgement in Step 306 of the traveling load judgement
routine indicates that the traveling load is large is detected on
the basis of a signal from the degree of opening of throttle
control device 22. When a judgement that the traveling load is
large is not given, the operation is advance to Step 402, and a
target degree of opening of the throttle valve 12 is set to a level
detected by the degree of opening of accelerator sensor 14. When a
judgement that the traveling load is large is given, the operation
is advanced to Step 403, and the target degree of opening of the
throttle valve 12 is set to a set level used during an operation
for protecting the automatic clutch from overheating, output torque
from of the internal combustion engine being thereby lowered.
[0037] Thus, in the embodiment 1 of the apparatus for protecting an
automatic clutch from overheating according to the present
invention, the traveling load judgement device 20 predictively
judges by a traveling load judgement routine whether the automatic
clutch 3 is ready to be overheated or not. The results of this
judgement are outputted to the throttle actuator control device 19.
When the overheating of the clutch is not predicted, a throttle
control operation corresponding to the degree of opening of the
accelerator is carried out. When the overheating of the clutch is
predicted, the throttle valve 12 is moved to and closed in a
position of a set degree of opening to reduce output torque from
the engine 1. Accordingly, even when a traveling load at the
vehicle starting time becomes large due to an obstacle, so that the
starting of the vehicle is prevented, the burning of the automatic
clutch 3 can be avoided.
Embodiment 2
[0038] FIG. 5 is a flow chart of a throttle control operation
describing the embodiment 2 of the apparatus for protecting an
automatic clutch from overheating according to the present
invention, and FIG. 6 a flow chart of a clutch control operation.
This embodiment 2 is formed as follows. When the traveling load
judgement device 20 judges that the traveling load is large in the
embodiment 1, the judgement device 20 supplies a signal to a degree
of opening of throttle control device 22 and a clutch disengagement
control device 21. Consequently, a throttle actuator control device
19 sets a degree of opening of a throttle valve 12 to a level of
the idling rotation of the engine 1 in accordance with a signal
from the degree of opening of throttle control unit 22, and a
clutch control device 18 disengages an electromagnetic clutch 3 in
accordance with a signal from the clutch disengagement control
device 21.
[0039] In a throttle control routine of FIG. 5, whether or not the
results of judgement in Step 306 in the traveling load judgement
routine described with reference to FIG. 3 for the embodiment 1
indicate that the traveling load is large is detected in Step 501.
When a judgement that the traveling load is large is not given, the
operation is advanced to Step 502, and a target degree of opening
of the throttle valve 12 is set to a level detected by a degree of
opening of accelerator sensor 14. When the traveling load is judged
large in Step 501, the operation is advanced to Step 503, and the
target degree of opening of the throttle valve 12 is set to a level
at which the engine 1 can continue to make an idling rotation
stably.
[0040] At the same time, in a control routine of FIG. 6, whether or
not the results of judgement in a traveling load judgement routine
indicate that the traveling load is large is detected in Step 601.
When a judgement that the traveling load is large is not given,
whether or not a shift position is in a traveling range is judged
in Step 602 on the basis of a signal from a shift range switch 15.
When the shift position is neither in a P range nor in a N range,
the operation is advanced to Step 603. In Step 603, an actual
vehicle speed is compared with a vehicle speed attained when the
clutch is directly engaged. When the actual vehicle speed is not
lower than the vehicle speed a directly engaged condition, a
judgement that the clutch is in a direct engagement mode is given
in Step 604. When the actual vehicle speed is lower than the
vehicle speed in a directly engaged condition, a judgement that the
clutch is in a slipping mode in which a semi-clutch-engaged
condition at a vehicle starting time is controlled is given in Step
605.
[0041] When a judgement that a traveling load is large is given in
Step 601, it is identical with the judgement given in the
above-mentioned traveling load judgement routine in Step 306.
Therefore, the operation is advanced to Step 606, in which the
clutch control device 18 changes the mode of the electromagnetic
clutch 3 into a disengagement mode. When a judgement that the shift
range is a P range or a N range is given in Step 602, the operation
is also advanced to Step 606, and the mode of the electromagnetic
clutch 3 is changed into a disengagement mode.
[0042] When a judgement that a traveling load is large is thus
predictively given in this embodiment of the apparatus for
protecting an automatic clutch from overheating, the rotation of
the internal combustion engine 1 is controlled to be an idling
rotation in accordance with a signal from the degree of opening of
throttle control device 22, and the electromagnetic clutch 3 is
controlled to be disengaged in accordance with a signal from the
clutch disengagement control device 21. Therefore, just as in the
case of the embodiment 1, the burning of the automatic clutch 3 can
be avoided even when a traveling load at the vehicle starting time
becomes large. Moreover, since the electromagnetic clutch 3 is
disengaged, a subsequent normal operation can be carried out
without accompanying an engine stall.
[0043] Although the above description of the control operation of
the control device 9 is narrowed down to a description of only the
controlling of a traveling load, the control unit 9 also carries
out the controlling of the transmission 5, and the controlling of
the electromagnetic clutch 3 and throttle actuator 10, which is
incidental to the controlling of the transmission 5, on the basis
of inputs of various kinds of sensors and a control program stored
in the memory 9b.
* * * * *