U.S. patent application number 13/324475 was filed with the patent office on 2012-05-10 for method for operating an internal combustion engine.
This patent application is currently assigned to AVL LIST GMBH. Invention is credited to Peter Ebner, Robert Fischer, Gunter Fraidl, Paul Kapus, Carsten Kaup, Wolfgang Kriegler, Thomas Pels.
Application Number | 20120116625 13/324475 |
Document ID | / |
Family ID | 37488147 |
Filed Date | 2012-05-10 |
United States Patent
Application |
20120116625 |
Kind Code |
A1 |
Pels; Thomas ; et
al. |
May 10, 2012 |
Method for Operating an Internal Combustion Engine
Abstract
A method for operating a hybrid drive in a vehicle with an
internal combustion engine and at least one electric machine
connected thereto which is in connection with at least one energy
storage device including operating the internal combustion engine
is operated in overload mode in at least one preferably exceptional
operating situation of the hybrid drive in order to avoid power
losses at low loading state of the energy storage device.
Inventors: |
Pels; Thomas; (Heiden,
DE) ; Kapus; Paul; (Judendorf, AT) ; Ebner;
Peter; (Graz, AT) ; Fischer; Robert; (Graz,
AT) ; Fraidl; Gunter; (Graz, AT) ; Kriegler;
Wolfgang; (Graz, AT) ; Kaup; Carsten;
(Coesfeld, DE) |
Assignee: |
AVL LIST GMBH
|
Family ID: |
37488147 |
Appl. No.: |
13/324475 |
Filed: |
December 13, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11991311 |
May 6, 2008 |
8136615 |
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PCT/AT2006/000359 |
Aug 31, 2006 |
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13324475 |
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Current U.S.
Class: |
701/22 ;
180/65.265; 60/605.3 |
Current CPC
Class: |
B60W 30/18054 20130101;
B60W 30/184 20130101; F01M 2001/0215 20130101; B60W 10/115
20130101; B60W 10/06 20130101; B60W 10/30 20130101; F16H 2059/446
20130101; B60W 2510/0623 20130101; B60K 6/48 20130101; B60W 20/15
20160101; Y02T 10/72 20130101; B60L 2260/12 20130101; H02P 21/00
20130101; Y02T 10/64 20130101; F01M 2001/123 20130101; Y02T 10/70
20130101; B60L 2240/28 20130101; B60W 20/00 20130101; F02B 39/14
20130101; B60L 2240/80 20130101; Y02T 10/7072 20130101; Y02T 10/62
20130101; F01M 2011/021 20130101; B60K 6/28 20130101; B60W 10/26
20130101; B60L 2210/20 20130101; B60K 6/46 20130101; B60L 2260/22
20130101; B60W 2710/065 20130101; B60Y 2400/435 20130101; B60L
50/61 20190201; B60L 2240/443 20130101; B60W 2520/10 20130101; B60W
10/02 20130101; B60W 10/10 20130101; B60W 2510/0657 20130101 |
Class at
Publication: |
701/22 ;
60/605.3; 180/65.265 |
International
Class: |
B60L 15/20 20060101
B60L015/20; F01M 1/12 20060101 F01M001/12 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 1, 2005 |
AT |
A 1432/2005 |
Sep 22, 2005 |
AT |
A 1565/2005 |
Nov 24, 2005 |
AT |
A 1904/2005 |
Nov 29, 2005 |
AT |
A 1927/2005 |
Claims
1-29. (canceled)
30. A method for operating an internal combustion engine which
comprises at least one turbocharger and at least one oil pump,
comprising the step of operating the oil pump for at least a
duration of the minimum coasting period with a cut-off command
following a high-load or full-load phase of the internal combustion
machine.
31. The method according to claim 30, with the oil pump being
driven by the internal combustion engine, comprising operating the
internal combustion engine driving the oil pump for at least the
duration of a minimum coasting period with a cut-off command
following a high-load or full-load phase.
32. The method according to claim 30, especially with an
electrically drivable oil pump, comprising operating the oil pump
for at least a minimum coasting period after the internal
combustion engine is cut off.
33. The method according to claim 32, wherein the minimum coasting
period is determined depending on at least one operating parameter,
including the speed of the turbocharger, the torque or the
injection quantity of the internal combustion engine.
34. The method according to claim 33, wherein the minimum coasting
period is predefined.
35. A method for operating a vehicle which comprises a serial
hybrid drive train with at least one internal combustion engine and
at least a first and second electric machine, with the first
electric machine being operated by the internal combustion machine
in the manner of a generator in at least one operating range and
the second electric machine drives directly or indirectly at least
one drive wheel of the vehicle, comprising operating the internal
combustion engine under partial load or in idle running at
standstill of the vehicle and/or when a door of the vehicle is
opened.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a method for operating a hybrid
drive in a vehicle with an internal combustion engine and at least
one electric machine connected thereto which is in connection with
an energy storage device. The invention further relates to a method
for determining differences in compression in a multi-cylinder
internal combustion engine which is mechanically rigidly connected
with a preferably variable-speed electric induction machine. The
invention further relates to a method for operating an internal
combustion engine, especially a hybrid vehicle which comprises at
least one exhaust turbocharger and at least one oil pump. The
invention further relates to a method for operating a vehicle which
comprises a serial hybrid drive train with at least one internal
combustion engine and at least a first and second electric machine,
with the first electric machine being operated in the manner of a
generator by the internal combustion engine in at least one
operating range and the second electric machine driving at least
one drive wheel of the vehicle in a direct or indirect manner.
[0003] 2. The Prior Art
[0004] A control system for a hybrid vehicle is known from JP
2003-041966 A, in which the internal combustion engine compensates
a torque loss of the electric machine when the electric machine is
not ready for operation.
[0005] The electric machine of a hybrid shall increase driving
power in many cases by positive moment (boosting function). The
reproducibility of this function is problematic, especially in the
case that the energy storage device is depleted or the electric
machine is unable to provide its maximum output, e.g. due to
overheating. In known systems, such situations will lead to drops
in performance of the vehicle drive which the driver may neither
foresee nor understand.
[0006] The compression of the cylinders is conventionally measured
via the spark plug or glow plug bores. This is relatively
time-consuming because spark plugs or glow plugs need to be removed
prior to measurement.
[0007] A device for testing an internal combustion engine is known
from JP 60256029 A2. The internal combustion engine is driven by an
electromotor and the drive torque is measured.
[0008] JP 60256028 A2 and JP 60256027 A2 also disclose similar
methods. The amount of the frictional resistances is derived on the
basis of the measured torque.
[0009] Especially in the case of hybrid vehicles with an internal
combustion engine with turbocharger, the lubrication of the
turbocharger is critical during the switch-off process of the
internal combustion engine after an operating phase with high speed
(e.g. in so-called start-stop operation) because the oil pump,
which is driven by the internal combustion engine for example, will
no longer convey any lubricating oil after switch-off although the
turbocharger can still run at high speed.
[0010] A control device for the generator of an electric vehicle is
known from JP 2003-134608 A2, with the operating range of the
vehicle being distinguished in manned and unmanned operation. In
manned operation, the generator is stopped as soon as a
predetermined loading state of the battery has been reached. In
unmanned operation, the generator is driven in such a way that it
will supply the more current to the battery the lower its loading
state is.
[0011] JP 2003-134607 A2 describes a similar method.
[0012] In the case of vehicles with serial hybrid drive train, the
internal combustion engine is operated with constant nominal speed
for driving the first electric machine. This allows high
efficiency, low consumption and low emissions. Such vehicles are
used for example in the operation of public-transit buses. The
disadvantageous aspect is that especially during the standstill of
the vehicle in the area of the bus stops for example there will be
a relatively high noise development by the internal combustion
engine.
[0013] It is the object of the invention to avoid such
disadvantages and to improve the drive behaviour of a hybrid
vehicle. It is also the object of the invention to provide a method
with which the compression of the individual cylinders can be
determined with as little effort as possible. It is a further
object of the invention to enable sufficient lubrication of the
turbocharger during the cut-off process. It is further an object of
the invention to reduce the noise emissions in vehicles with serial
hybrid drive trains.
SUMMARY OF THE INVENTION
[0014] This is achieved in accordance with the invention in such a
way that the internal combustion engine is operated in overload
mode in at least one preferably exceptional operating situation of
the hybrid drive.
[0015] It is preferably provided that the internal combustion
engine is operated in overload mode when the loading state of the
energy storage device falls under a minimum value and/or the
demanded power is higher than the sum total of the driving power of
the internal combustion engine and the electric machine.
[0016] Especially in hazardous situations, a sufficiently high
torque can be provided to overcome critical situations through
temporary overload operation of the internal combustion engine.
[0017] The internal combustion engine is operated in an "overload
manner" in overload operation without taking into account the
emissions and fatigue strength. This occurs by larger injected
quantities, changed ignition point, increased boost pressure,
etc.
[0018] It is especially advantageous when the internal combustion
engine is operated in overload mode when, outside of the proper
application area of the electric machine, the full drive power of
the internal combustion engine operated in normal load mode is
demanded and additionally charge power for loading the energy
storage device is to be provided. In this way it is possible to
provide sufficient drive torque and recharge the empty energy
storage device.
[0019] It is further advantageous when the internal combustion
engine, within the ordinary application area of the electric
machine, is operated in overload mode when respective drive power
is demanded and support power for the internal combustion engine
operated in normal load mode is not available by the electric
machine.
[0020] By additional enrichment of the mixture and/or by increasing
the boost pressure of the charged internal combustion engine and/or
by adjusting the control times or the stroke of the charge-changing
valves it is possible to operate the same in overload mode.
[0021] The energy management is designed in such a way that in the
case of repeated starting and acceleration processes the consumed
and recharged energy is the same and thus enables reciprocating
operation.
[0022] A displacement of the load point can be made via the
transmission which can be arranged as a manual transmission or dual
clutch transmission. The gear ratio in the last gear can be
designed at 40 to 55 kph for 1000 min.sup.-1 engine speed.
[0023] As an alternative to this, a displacement of the load point
can also be achieved by loading the electric machine or supporting
the internal combustion engine by the electric machine.
[0024] During the so-called "turbo lag", the electric machine can
be operated in a supporting manner in order to compensate power
losses in this phase.
[0025] When the vehicle is driven only electrically by the electric
machine, then it is advantageous to separate the internal
combustion engine from the drive train by a clutch in order to
avoid drag losses.
[0026] It is also possible to reduce the friction of the dragged
internal combustion engine by adjusting the control times, change
of valve stroke or valve deactivation.
[0027] Double-layer capacitors are best suited for rapid recharging
processes. Rechargeable batteries can be used as energy storage
device for normal hybrid functions however. It is especially
advantageous when, depending on the requirements, different energy
storage devices are used, i.e. both double-layer capacitors as well
as batteries.
[0028] In order to determine the compression of individual
cylinders in a simple manner it is provided that phase currents
and/or the phase voltages and the speed of the induction machine
are measured continuously or discontinuously and the torque on the
shaft of the induction machine is derived therefrom, and that the
torque curve is associated with a compression pressure curve, with
preferably the internal combustion engine being operated at the
measuring time in a non-ignited manner and dragged by the induction
machine.
[0029] An especially simple measuring possibility is obtained when
differences in compression between the cylinders is derived from
the different torque peaks.
[0030] In the case of field-oriented feedback control systems for
induction machines, the torque on the shaft is calculated from
phase currents, phase voltage and speed for the torque. Various
methods are known which are based on stator, air-gap or rotor flux
of the induction machine and differ in the machine model. The
common aspect in this method is the goal of determining magnetic
flux without any constructional interventions for detection by
measurement. The machine model calculates state quantities of the
machine which are made available as actual values to the flux and
moment controller. In such systems, the torque is the actuating
variable for speed and voltage regulations. No additional measured
quantities are required in the method in accordance with the
invention because the torque is usually calculated anyway for speed
and voltage regulation.
[0031] The electric induction machine is mechanically rigidly
connected with the internal combustion engine. In order to ensure
that all working strokes of a cylinder are detected, the torque
progression with reference to crank angle is recorded over at least
two rotations of the crankshaft. Differences in compression in the
individual cylinders can be derived from the torque progression of
the induction machine by comparison of the extreme values. The
torque amplitude is thereby dependent on the pressure in the
cylinders. When an internal combustion engine is cranked in a
non-ignited manner by a crankshaft starter-generator, it can be
derived from the comparison of the torque amplitudes which cylinder
has reduced compression pressure. When the electric induction
machine is driven with constant torque, the compression pressure
can be derived from the speed progression.
[0032] A diagnostic function implemented in the application
software can provide information on the compression loss in
individual cylinders in a rapid and simple way. It is not necessary
to make any mechanical changes such as the removal of spark or glow
plugs for example. Optionally, operating points can be found which
allow diagnostics during operation of the vehicle and indicate a
defect early on.
[0033] With the method in accordance with the invention, the
compression test by means of a diagnostic function can be
substantially simplified with the help of an electric machine. It
is especially possible to monitor the cylinder compression
continually.
[0034] A sufficient lubrication of the turbocharger during a
cut-off process can be achieved when the oil pump is continued to
be operated over a minimum coasting period during a cut-off command
preferably following a high-load or full-load phase of the internal
combustion engine
[0035] Especially in the case of an oil pump driven by the
crankshafts in the internal combustion engine, it is especially
advantageous when the internal combustion engine is operated under
partial load or idle running for at least a minimum coasting
period. When using an electrically drivable oil pump however, it
can be provided that the oil pump is operated for at least a
minimum coasting period after the cut-off of the internal
combustion engine. This ensures a sufficient lubrication of the
bearings of the exhaust-gas turbine.
[0036] In order to keep the minimum coasting period as short as
possible, it is advantageous when the minimum coasting period is
determined depending on at least one operating parameter,
preferably the speed of the turbocharger, the torque or the
injection quantity of the internal combustion engine, preferably at
the time of the cut-off command.
[0037] In order to reduce noise emissions, it is provided that the
internal combustion engine is operated under partial load or idle
running at standstill of the vehicle and/or when the vehicle door
is opened.
[0038] Due to the fact that the internal combustion engine is
operated in partial load or in idle running when charging is
required, i.e. when the battery charge state is low, the sound
pressure level can thus be reduced considerably. Although the
internal combustion engine does not run in the optimal operating
range, the comfort of the vehicle and thus the acceptance of the
drive concept will thus be improved. The operating strategy can be
employed not only at bus stops but also at stops caused by the
traffic such as before crossings or the like.
[0039] The invention is now explained in greater detail below by
reference to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] FIG. 1 shows a torque-speed diagram;
[0041] FIG. 2 schematically shows a hybrid drive for performing the
method in accordance with the invention;
[0042] FIG. 3 schematically shows an arrangement for performing the
method in accordance with the invention;
[0043] FIG. 4 shows a torque-crank angle diagram, and
[0044] FIG. 5 shows an internal combustion engine for a hybrid
vehicle.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0045] FIG. 1 shows a diagram in which the torque M is entered over
the engine speed n. M.sub.E designates the torque of the electric
machine 3 and M.sub.M the torque of internal combustion engine 2.
The part of the torque characteristics of internal combustion
engine 2 designated with M.sub.O shows the overload range.
[0046] For realization purposes, a simple hybrid drive 1 (so-called
mild hybrid) with an internal combustion engine 2 and an electric
machine 3 which is connected with an energy storage device 4 is
suitable. The electric machine 3 is mechanically connected with the
crankshaft 5 of the internal combustion engine. A transmission 7
which is arranged as a manual transmission or dual clutch
transmission for example is arranged in the drive train to the
drive wheels 6. The clutch 8 can be arranged between the internal
combustion engine 2 and the electric machine 3. It is also possible
to install two clutches 8, 9.
[0047] In this embodiment, the electric machine 3 supports the
internal combustion engine 2 beneath a speed of 1500 min.sup.-1, so
that the torque is obtained as the sum total of the torque M.sub.M
of internal combustion engine 2 and torque M.sub.E of electric
machine 3. Beyond 1500 min.sup.-1 the driving torque is only
provided by the internal combustion engine 2. The driver is always
provided with the same torque. When the energy storage device 4 is
empty, the internal combustion engine is operated in overload mode.
The energy storage device is loaded and the nominal full-load
torque is supplied to the output shaft.
[0048] When the energy storage device 4 is emptied after a number
of moving off processes it is possible to increase the torque
M.sub.M of the internal combustion engine 2 above 1500 min.sup.-1
to such an extent that loading of the electric energy storage
device 4 is enabled, although a torque of approximately 300 Nm is
still available for driving the vehicle. This is achieved in such a
way that the internal combustion engine 2 is operated by increasing
the boost pressure and slight enrichment in overload mode. The
overload can also occur for example by changing the control times
and/or the valve stroke. A combination of several measures is also
possible.
[0049] An exemplary critical situation is moving off when on a
mountain with a speed only slightly above the idling speed (e.g.
1250 min.sup.-1). Shifting up to the next gear occurs at 2000
min.sup.-1 for example. In the operating range from 1250 min.sup.-1
to 1500 min.sup.-1, energy is taken from the energy storage device
4 and the electric machine 3 supplies torque. In the operating
range between 1500 min.sup.-1 to 2000 min.sup.-1, the internal
combustion engine 2 is operated in overload mode (when energy
storage device 4 is depleted). The torque M which lies over the
nominal torque (300 Nm in the example) is used for recharging the
energy storage device 4. It is desirable in this respect that at
the lowest possible speed n it is possible to recharge the energy
storage device 4 with nominal output of the electric machine 3.
[0050] It is the goal of the operation that the energy which is
required beneath 1500 min.sup.-1 can be recharged in operation
above 1500 min.sup.-1 up to a switching speed (worst case
condition: low switching speed). The overload energy must cover the
recharging of the energy storage device 4 and the efficiency of the
recharging at the lowest possible speed n.
[0051] In contrast to current hybrid concepts, this means the
following for the internal combustion engine: The maximum torque
(crossover between consumption and recharging) must occur at the
lowest possible speeds n. In the case of known hybrid concepts, an
especially cost-effective internal combustion engine will be used,
or an internal combustion engine which is designed rather for
lowest consumption than for best torque.
[0052] In contrast to conventional hybrid concepts, the charged
internal combustion engine 2 which has a high torque at low speeds
allows with the hybrid drive in accordance with the invention a
hybrid concept without power split. The displacement of the load
point does not mainly occur via power splitting between electric
machine 3 and internal combustion engine 2, but via a transmission
with long final gear ratio. Therefore, no power-splitting
transmission and consequently no high development and investment
costs are required. At the same time, the concept as described here
can also be used as an additional function for existing
transmissions. A slight additional displacement of the load point
is still possible. Costs can thus be reduced substantially.
[0053] The electric machine 3 can be used as follows: [0054] Load
point displacement: When the energy storage device 4 is provided
with sufficient energy, the electric machine 3 can be used in a
supporting manner; when the energy storage device is depleted or
loadable, it can be used in a loading manner in order to shift the
internal combustion engine to the optimal operating point (minimum
consumption point). [0055] Transient support: The electric machine
3 can be used for bridging the so-called "turbo lag". During the
period of the run-up of the turbocharger, a linear build-up of
torque can be ensured by means of the electric machine 3. [0056]
Electric driving: It is possible to drive in a purely electric way
when the electric energy storage device 4 is sufficiently loaded.
In the case of a rigid connection between the electric machine 3
and the internal combustion engine 2, the electric machine 3 is
supplied with current in such a way that the unevenness in rotation
of the dragged internal combustion engine 2 is compensated. The
internal combustion engine 2 is operated in a mode minimizing
friction. When using a clutch 8 between electric machine 3 and
internal combustion engine 2, it is possible to drive electrically
when the internal combustion engine 2 is uncoupled.
[0057] The energy storage device 4 can consist of double-layer
capacitors (supercaps) and/or conventional rechargeable batteries.
Double-layer capacitors are especially suitable for rapid
recharging. For electric driving operation it is possible to use
rechargeable batteries. In the overall concept it is therefore
possible to also use two different energy storage devices.
[0058] The method in accordance with the invention is not limited
to certain types and arrangements of hybrid concepts, but can
rather be used in a large variety of hybrid drives.
[0059] A variable-speed electric induction machine 12 is connected
in a mechanically rigid way to an internal combustion engine 11
with several cylinders, as is shown in FIG. 3. The feedback control
of the induction machine 12 occurs by means of a machine controller
13 through pulse-width modulation PWM. Reference numeral 14 relates
to a flux controller and reference numeral 5 to a speed
controller.
[0060] The torque M on the shaft is calculated in the
field-oriented machine controller 13 for the induction machine 12
from the phase currents, the phase voltage and the speed n of the
crankshaft of the internal combustion engine 11. The magnetic flux
.PHI. is determined for measurement detection without any
constructional interventions. The machine model 16 calculates the
state quantities of torque M and magnetic flux .PHI. of the
induction machine 12 which are made available as actual values to
the flux controller 14 and the torque controller 17. The torque M
forms the actuating variable in speed and voltage feedback
control.
[0061] FIG. 4 shows the curve of the torque M over the crank angle
.alpha. for a multi-cylinder internal combustion engine 11. The
cyclic fluctuations of the torque M are caused by the compression
of the individual cylinders. Differences in compression between the
cylinders can be concluded from the clearly recognizable different
torque peaks.
[0062] A rapid evaluation of the results can be achieved when a
diagnostic function is implemented in the application software.
[0063] FIG. 5 schematically shows an internal combustion engine 21
for a hybrid vehicle, comprising an intake strand 22 and an exhaust
strand 23. An exhaust-gas turbocharger 24 is arranged in the intake
and exhaust strand 22, 23 whose bearings 25 are supplied with
lubricating oil by an oil pump 27 driven by the crankshaft 26 of
the internal combustion engine 21. Especially in the case of hybrid
vehicles there will be operating phases in which the internal
combustion machine 21 is switched off directly after full-load
operation. Since the oil pump 27 is usually driven with the other
secondary drives via the crankshaft 26, it no longer supplies any
lubricating oil to the bearings 25 of the exhaust-gas turbocharger
24 after the cut-off of the internal combustion engine, although
the turbocharger 24 can still revolve at high speed. This can lead
to a lack of lubricating oil of the bearings 25 of the exhaust-gas
turbocharger 24 and to its destruction:
[0064] In order to avoid this, a minimum coasting period is
determined from which a destruction-free cut-off is possible on the
basis of the profile of output-specific engine parameters (moment,
injected quantity), the speed profile of the internal combustion
engine 21 and/or the speed of the exhaust-gas turbocharger 24. The
progression of the specific quantities is examined in a time window
and the coasting duration .DELTA.t or the earliest possible cut-off
time is determined. Once the command for cut-off has been given to
the internal combustion engine 21, it will coast for a
predetermined coasting period .DELTA.t in order to supply the
bearings 25 of the exhaust-gas turbocharger 24 sufficiently with
lubricating oil via the oil pump 27.
* * * * *