U.S. patent application number 09/785226 was filed with the patent office on 2001-09-06 for control apparatus for idling stop of internal combustion engine and vehicle with the apparatus mounted thereon.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. Invention is credited to Hirose, Kiyoo, Ito, Yukikazu, Kato, Senji, Kitamura, Tooru, Takahashi, Jun.
Application Number | 20010018903 09/785226 |
Document ID | / |
Family ID | 18580495 |
Filed Date | 2001-09-06 |
United States Patent
Application |
20010018903 |
Kind Code |
A1 |
Hirose, Kiyoo ; et
al. |
September 6, 2001 |
Control apparatus for idling stop of internal combustion engine and
vehicle with the apparatus mounted thereon
Abstract
The technique of the present invention reduces or even omits
potential shocks and vibrations arising due to the coupling action
of a coupling mechanism at the time of starting an internal
combustion engine, and ensures a quick restart of the internal
combustion engine. In a vehicle with an idling stop control
apparatus of the present invention mounted thereon, a control unit
inputs an inverted phase current Eon, which is determined according
to the energy absorbing state of a transmission belt, into an
auxiliary machinery driving electric motor, so as to brake
rotations of the auxiliary machinery driving electric motor. After
the input of the inverted phase current Eon into the auxiliary
machinery driving electric motor, the control unit couples an
electromagnetic clutch to link a crankshaft of the internal
combustion engine with the auxiliary machinery driving electric
motor. The value of the inverted phase current Eon is varied
according to the energy absorbing state of the transmission belt.
The braking force of the auxiliary machinery driving electric motor
is thus varied according to the energy absorbing state of the
transmission belt.
Inventors: |
Hirose, Kiyoo; (Nagoya-shi,
JP) ; Kato, Senji; (Nishikamo-gun, JP) ;
Takahashi, Jun; (Toyota-shi, JP) ; Ito, Yukikazu;
(Nishikamo-gun, JP) ; Kitamura, Tooru;
(Nishikamo-gun, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
277 S. WASHINGTON STREET, SUITE 500
ALEXANDRIA
VA
22314
US
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
|
Family ID: |
18580495 |
Appl. No.: |
09/785226 |
Filed: |
February 20, 2001 |
Current U.S.
Class: |
123/179.4 ;
180/65.25; 180/65.27; 180/65.28; 307/10.6; 903/919 |
Current CPC
Class: |
Y02T 10/64 20130101;
F02D 41/042 20130101; B60L 2240/421 20130101; Y10S 903/919
20130101; B60W 10/06 20130101; Y02T 10/62 20130101; B60K 6/547
20130101; B60W 2710/081 20130101; F02D 2041/389 20130101; B60W
20/00 20130101; B60W 2555/20 20200201; B60W 2510/0676 20130101;
B60K 6/48 20130101; B60L 2240/441 20130101; B60W 2510/0638
20130101; B60W 10/30 20130101 |
Class at
Publication: |
123/179.4 ;
307/10.6 |
International
Class: |
F02N 011/00; H02G
003/00; F02P 009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 6, 2000 |
JP |
2000-060139 |
Claims
What is claimed is:
1. An idling stop control apparatus mounted on a vehicle, wherein
auxiliary machinery is driven by means of either one of an internal
combustion engine and an electric motor, and an output shaft of
said internal combustion engine and an output shaft of said
electric motor are linked with each other via a coupling mechanism
that is coupled to connect said internal combustion engine with
said electric motor and is released to disconnect said internal
combustion engine from said electric motor, said coupling mechanism
being released and said auxiliary machinery being driven by means
of said electric motor via a transmission belt while said internal
combustion engine is at a stop, said idling stop control apparatus
comprising: a decision unit that determines whether a driving stop
condition or a driving restart condition of said internal
combustion engine is fulfilled; a braking load specification unit
that, when the driving restart condition of said internal
combustion engine is fulfilled, specifies a braking load to be
applied to said electric motor, in order to reduce electric motor
velocity or number of revolutions of said electric motor according
to a kinetic energy absorbing state of said transmission belt; a
drive stand-by unit that, when the driving restart condition of
said internal combustion engine is fulfilled and said coupling
mechanism is released, causes said output shaft of said internal
combustion engine to be coupled with said output shaft of said
electric motor via said coupling mechanism after application of the
specified braking load to said electric motor; and an internal
combustion engine operation control unit that executes a series of
processing to restart operation of said internal combustion engine
after said internal combustion engine is coupled with said electric
motor via said coupling mechanism.
2. An idling stop control apparatus in accordance with claim 1,
wherein said vehicle further comprises a transmission belt
elasticity measurement unit that measures elasticity of said
transmission belt, and said braking load specification unit
determines the kinetic energy absorbing state of said transmission
belt based on the observed elasticity of said transmission belt and
increases the braking load with a decrease in observed elasticity
of said transmission belt.
3. An idling stop control apparatus in accordance with claim 1,
wherein said vehicle comprises a transmission belt temperature
measurement unit that measures temperature of said transmission
belt, and said braking load specification unit determines the
kinetic energy absorbing state of said transmission belt based on
the observed temperature of said transmission belt and increases
the braking load with a decrease in observed temperature of said
transmission belt.
4. An idling stop control apparatus in accordance with claim 3,
wherein said transmission belt temperature measurement unit
comprises a cooling fluid temperature measurement unit that
measures temperature of a cooling fluid passing through said
internal combustion engine, and said braking load specification
unit determines the kinetic energy absorbing state of said
transmission belt based on the observed temperature of the cooling
fluid and increases the braking load with a decrease in observed
temperature of the cooling fluid.
5. An idling stop control apparatus in accordance with claim 3,
wherein said transmission belt temperature measurement unit
comprises an engine velocity accumulation unit that accumulates
engine velocity or number of revolutions of said internal
combustion engine from a start to a stop of driving of said
internal combustion engine, and said braking load specification
unit determines the kinetic energy absorbing state of said
transmission belt based on the accumulated engine velocity and
decreases the braking load with an increase in accumulated engine
velocity.
6. An idling stop control apparatus in accordance with claim 3,
wherein said transmission belt temperature measurement unit
comprises an electric motor velocity accumulation unit that
accumulates the electric motor velocity or the number of
revolutions of said electric motor after a stop of driving of said
internal combustion engine, and said braking load specification
unit determines the kinetic energy absorbing state of said
transmission belt based on the accumulated electric motor velocity
and decreases the braking load with an increase in accumulated
electric motor velocity.
7. An idling stop control apparatus in accordance with either one
of claims 5 and 6, wherein said transmission belt temperature
measurement unit further comprises an outside air temperature
measurement unit that measures outside air temperature, and said
braking load specification unit increases a rate of decrease of the
braking load with an increase in observed outside air
temperature.
8. A vehicle having an idling stop function to selectively stop and
restart driving an internal combustion engine according to a
driving state of said vehicle, wherein auxiliary machinery is
driven by means of an electric motor while said internal combustion
engine is at a stop and by means of said internal combustion engine
while said internal combustion engine is in active state, said
vehicle comprising: a coupling mechanism that links an output shaft
of said internal combustion engine with an output shaft of said
electric motor, such as to be coupled to connect said internal
combustion engine with said electric motor and to be released to
disconnect said internal combustion engine from said electric
motor; a transmission belt that is laid through said output shaft
of said internal combustion engine, an input shaft of said
auxiliary machinery, and said output shaft of said electric motor;
a transmission belt state detection unit that detects a kinetic
energy absorbing state of said transmission belt; and an idling
stop control unit that specifies a rate of decrease in electric
motor velocity or number of revolutions of said electric motor
based on the detected kinetic energy absorbing state of said
transmission belt, and when a driving restart condition for
restarting operation of said internal combustion engine is
fulfilled, lowers the electric motor velocity by the specified rate
of decrease, causes said output shaft of said internal combustion
engine to be coupled with said output shaft of said electric motor
via said coupling mechanism, and subsequently carries out a series
of processing to restart driving said internal combustion
engine.
9. A vehicle in accordance with claim 8, wherein said transmission
belt state detection unit detects the kinetic energy absorbing
state of said transmission belt based on elasticity of said
transmission belt, and said idling stop control unit enhances the
rate of decrease in electric motor velocity with a decrease in
elasticity of said transmission belt.
10. A vehicle in accordance with claim 8, wherein said transmission
belt state detection unit detects the kinetic energy absorbing
state of said transmission belt based on temperature of said
transmission belt, and said idling stop control unit enhances the
rate of decrease in electric motor velocity with a decrease in
temperature of said transmission belt.
11. A vehicle in accordance with claim 10, said vehicle further
comprising: a heat dissipation unit that is arranged on a windward
side of said transmission belt to dissipate heat of a cooling
fluid, which has passed through and cooled down said internal
combustion engine; and a cooling fluid temperature measurement unit
that measures temperature of the cooling fluid, wherein said
transmission belt state detection unit calculates the temperature
of said transmission belt from the observed temperature of the
cooling fluid and detects the kinetic energy absorbing state of
said transmission belt based on the calculated temperature of said
transmission belt.
12. A vehicle in accordance with either one of claims 10 and 11,
said vehicle further comprising an engine velocity accumulation
unit that accumulates engine velocity or number of revolutions of
said internal combustion engine from a start to a stop of driving
of said internal combustion engine, wherein said transmission belt
state detection unit calculates the temperature of said
transmission belt from the accumulated engine velocity and detects
the kinetic energy absorbing state of said transmission belt based
on the calculated temperature of said transmission belt.
13. A vehicle in accordance with either one of claims 10 and 11,
said vehicle further comprising an electric motor velocity
accumulation unit that accumulates electric motor velocity or
number of revolutions of said electric motor after a stop of
driving of said internal combustion engine, wherein said
transmission belt state detection unit calculates the temperature
of said transmission belt from the accumulated electric motor
velocity and detects the kinetic energy absorbing state of said
transmission belt based on the calculated temperature of said
transmission belt.
14. A vehicle in accordance with either one of claims 12 and 13,
said vehicle further comprising an outside air temperature
measurement unit that measures outside air temperature, wherein
said transmission belt state detection unit calculates the
temperature of said transmission belt from the observed outside air
temperature in addition to at least one of the observed temperature
of the cooling fluid, the accumulated engine velocity, and the
accumulated electric motor velocity and detects the kinetic energy
absorbing state of said transmission belt based on the calculated
temperature of said transmission belt.
15. A vehicle in accordance with any one of claims 8 through 14,
wherein said idling stop control unit stops driving said internal
combustion engine and releases said coupling mechanism when a
driving stop condition of said internal combustion engine is
fulfilled.
16. A vehicle having an idling stop function to selectively stop
and restart driving an internal combustion engine according to a
driving state of said vehicle, wherein auxiliary machinery is
driven by means of an electric motor via a transmission belt while
said internal combustion engine is at a stop and by means of said
internal combustion engine while said internal combustion engine is
in active state, said vehicle comprising: a coupling mechanism that
links an output shaft of said internal combustion engine with an
output shaft of said electric motor, such as to be coupled to
connect said internal combustion engine with said electric motor
and to be released to disconnect said internal combustion engine
from said electric motor; a target braking velocity determination
unit that determines a target braking velocity for braking said
electric motor prior to a restart of driving of said internal
combustion engine by taking into account temperature of said
transmission belt; and an idling stop control unit that, when a
driving restart condition for restarting operation of said internal
combustion engine is fulfilled, drives said electric motor at the
target braking velocity, causes said output shaft of said internal
combustion engine to be coupled with said output shaft of said
electric motor via said coupling mechanism, and subsequently
carries out a series of processing to restart driving said internal
combustion engine.
17. A vehicle in accordance with claim 16, said vehicle further
comprising: a heat dissipation unit that is arranged on a windward
side of said transmission belt to dissipate heat of a cooling
fluid, which has passed through and cooled down said internal
combustion engine; and a cooling fluid temperature measurement unit
that measures temperature of the cooling fluid, wherein said target
braking velocity determination unit takes into account the
temperature of said transmission belt based on the observed
temperature of the cooling fluid and lowers the target braking
velocity with a decrease in observed temperature of the cooling
fluid.
18. A vehicle in accordance with claim 17, said vehicle further
comprising an engine velocity accumulation unit that accumulates
engine velocity or number of revolutions of said internal
combustion engine from a start to a stop of driving of said
internal combustion engine, wherein said target braking velocity
determination unit takes into account the temperature of said
transmission belt based on the accumulated engine velocity and
raises the target braking velocity with an increase in accumulated
engine velocity.
19. A vehicle in accordance with claim 17, said vehicle further
comprising an electric motor velocity accumulation unit that
accumulates electric motor velocity or number of revolutions of
said electric motor after a stop of driving of said internal
combustion engine, wherein said target braking velocity
determination unit takes into account the temperature of said
transmission belt based on the accumulated electric motor velocity
and raises the target braking velocity with an increase in
accumulated electric motor velocity.
20. A vehicle in accordance with either one of claims 18 and 19,
said vehicle further comprising an outside air temperature
measurement unit that measures outside air temperature, wherein
said target braking velocity determination unit varies a rate of
increase in target braking velocity according to the observed
outside air temperature.
21. A vehicle in accordance with claim 20, wherein said target
braking velocity determination unit enhances the rate of increase
in target braking velocity with an increase in observed outside air
temperature.
22. A vehicle in accordance with any one of claims 16 through 21,
wherein said idling stop control unit stops driving said internal
combustion engine and releases said coupling mechanism when a
driving stop condition of said internal combustion engine is
fulfilled.
23. A method of controlling idling stop in a vehicle that has an
idling stop function to selectively stop and restart driving an
internal combustion engine according to a driving state of said
vehicle, wherein auxiliary machinery is driven by means of an
electric motor while said internal combustion engine is at a stop,
said method comprising the steps of: detecting a kinetic energy
absorbing state of a transmission belt that is laid through said
internal combustion engine, said electric motor, and said auxiliary
machinery; determining whether or not a driving restart condition
for restarting operation of said internal combustion engine is
fulfilled; when it is determined that the driving restart condition
is fulfilled, specifying a rate of decrease in electric motor
velocity or number of revolutions of said electric motor based on
the detected kinetic energy absorbing state of said transmission
belt; and lowering the electric motor velocity by the specified
rate of decrease and subsequently causing said output shaft of said
internal combustion engine to be coupled with said output shaft of
said electric motor via said coupling mechanism, so as to restart
driving said internal combustion engine.
24. A method in accordance with claim 23, said method further
comprising the steps of: measuring elasticity of said transmission
belt; detecting the kinetic energy absorbing state of said
transmission belt based on the observed elasticity of said
transmission belt; and enhancing the rate of decrease in electric
motor velocity with a decrease in observed elasticity of said
transmission belt.
25. A method in accordance with claim 23, said method further
comprising the steps of: measuring temperature of said transmission
belt; detecting the kinetic energy absorbing state of said
transmission belt based on the observed temperature of said
transmission belt; and enhancing the rate of decrease in electric
motor velocity with a decrease in observed temperature of said
transmission belt.
26. A method in accordance with claim 25, said method further
comprising the steps of: measuring temperature of a cooling fluid
that passed through said internal combustion engine; and enhancing
the rate of decrease in electric motor velocity with a decrease in
observed temperature of the cooling fluid.
27. A method in accordance with claim 26, said method further
comprising the steps of: accumulating engine velocity or number of
revolutions of said internal combustion engine from a start to a
stop of driving of said internal combustion engine; and lowering
the rate of decrease in electric motor velocity with an increase in
accumulated engine velocity.
28. A method in accordance with claim 26, said method further
comprising the steps of: accumulating electric motor velocity or
number of revolutions of said electric motor after a stop of
driving of said internal combustion engine; and lowering the rate
of decrease in electric motor velocity with an increase in
accumulated electric motor velocity.
29. A method in accordance with either one of claims 27 and 28,
said method further comprising the steps of: measuring an outside
air temperature; and enhancing the rate of decrease in electric
motor velocity with an increase in observed outside air
temperature.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a technique that controls
idling stop of an internal combustion engine, which is carried out
according to the driving state of a vehicle.
[0003] 2. Description of the Related Art
[0004] Some proposed vehicles have an idling stop control function
that stops driving an internal combustion engine at a temporary
stop of the vehicle, for example, at a traffic light during a drive
of the vehicle, and restarts driving the internal combustion engine
in response to a driver's requirement for a start. In such vehicles
having the function of automatically stopping and restarting the
operation of the internal combustion engine, an auxiliary machinery
driving electric electric motor is linked with the internal
combustion engine and auxiliary machinery via fan belts to allow
mutual connection thereof. While the internal combustion engine is
at a stop, the auxiliary machinery like a water pump is driven by
means of the auxiliary machinery driving electric electric motor.
In the active state of the internal combustion engine, on the other
hand, the auxiliary machinery is driven by means of the internal
combustion engine. In order to disconnect the internal combustion
engine from the driving system and reduce the loading of the
auxiliary machinery driving electric electric motor while the
auxiliary machinery is driven by means of the auxiliary machinery
driving electric electric motor, a clutch (coupling mechanism) is
interposed between the internal combustion engine and the auxiliary
machinery driving electric electric motor to couple and release the
internal combustion engine with and from the auxiliary machinery
driving electric motor.
[0005] The auxiliary machinery driving electric motor also
functions as the electric motor that restarts driving the internal
combustion engine. At a start of driving the internal combustion
engine, the clutch couples the internal combustion engine with the
auxiliary machinery driving electric motor, which is currently
driving the auxiliary machinery. This raises the velocity of the
internal combustion engine to a starting speed of revolutions. One
proposed technique couples the clutch after reduction of the
velocity of the auxiliary machinery driving electric motor at a
restart of driving the internal combustion engine, in order to
reduce the occurrence of potential shocks and vibrations due to the
velocity difference between the internal combustion engine and the
auxiliary machinery driving electric motor, which is currently
driving the auxiliary machinery.
[0006] In some driving states of the vehicle, the shocks and
vibrations (energy) arising due to the coupling action of the
clutch are not sufficiently absorbed by the fan belt. For example,
in the cold time, partly because of the low temperature of the fan
belt, the shocks and vibrations occurring due to the coupling
action of the clutch are not sufficiently absorbed in the course of
restarting the internal combustion engine under the idling stop
control. Enhancing the rate of decrease in number of revolutions of
the auxiliary machinery driving electric motor or in electric motor
velocity to ensure the sufficient absorption, on the other hand,
does not fulfil the requirement of quick restart of the internal
combustion engine.
SUMMARY OF THE INVENTION
[0007] The object of the present invention is thus to reduce or
even omit potential shocks and vibrations arising due to the
coupling action of a coupling mechanism at the time of starting an
internal combustion engine, and to ensure a quick restart of the
internal combustion engine.
[0008] At least part of the above and the other related objects is
attained by an idling stop control apparatus mounted on a vehicle,
wherein auxiliary machinery is driven by means of either one of an
internal combustion engine and an electric motor, and an output
shaft of the internal combustion engine and an output shaft of the
electric motor are linked with each other via a coupling mechanism
that is coupled to connect the internal combustion engine with the
electric motor and is released to disconnect the internal
combustion engine from the electric motor. The coupling mechanism
is released and the auxiliary machinery is driven by means of the
electric motor via a transmission belt while the internal
combustion engine is at a stop. The idling stop control apparatus
includes: a decision unit that determines whether a driving stop
condition or a driving restart condition of the internal combustion
engine is fulfilled; a braking load specification unit that, when
the driving restart condition of the internal combustion engine is
fulfilled, specifies a braking load to be applied to the electric
motor, in order to reduce electric motor velocity or number of
revolutions of the electric motor according to a kinetic energy
absorbing state of the transmission belt; a drive stand-by unit
that, when the driving restart condition of the internal combustion
engine is fulfilled and the coupling mechanism is released, causes
the output shaft of the internal combustion engine to be coupled
with the output shaft of the electric motor via the coupling
mechanism after application of the specified braking load to the
electric motor; and an internal combustion engine operation control
unit that executes a series of processing to restart operation of
the internal combustion engine after the internal combustion engine
is coupled with the electric motor via the coupling mechanism.
[0009] In the idling stop control apparatus of the present
invention, the braking load to be applied to the electric motor is
specified, in order to reduce the number of revolutions of the
electric motor or the electric motor velocity according to the
kinetic energy absorbing state of the transmission belt. This
arrangement effectively reduces or even omits potential shocks and
vibrations arising due to the coupling action of the coupling
mechanism at the time of starting the internal combustion engine,
and ensures a quick restart of the internal combustion engine.
[0010] In accordance with one aspect of the idling stop control
apparatus of the present invention, the vehicle has a transmission
belt elasticity measurement unit that measures elasticity of the
transmission belt, and the braking load specification unit
determines the kinetic energy absorbing state of the transmission
belt based on the observed elasticity of the transmission belt and
increases the braking load with a decrease in observed elasticity
of the transmission belt. In accordance with another aspect, the
vehicle has a transmission belt temperature measurement unit that
measures temperature of the transmission belt, and the braking load
specification unit determines the kinetic energy absorbing state of
the transmission belt based on the observed temperature of the
transmission belt and increases the braking load with a decrease in
observed temperature of the transmission belt.
[0011] The kinetic energy absorbing state of the transmission belt
represents the state that is capable or incapable of sufficiently
absorbing energy like shocks and vibrations, and correlates with
the properties, such as the elasticity and the hardness, of the
transmission belt. Namely measurement of the elasticity of the
transmission belt results in specifying the kinetic energy
absorbing state of the transmission belt. The properties like the
elasticity and the hardness of the transmission belt correlate with
the temperature of the transmission belt. These properties can thus
be specified according to the temperature of the transmission belt.
Under the condition of low temperatures, the transmission belt
tends to be cured and lose its elasticity and thus hardly absorbs
the potential shocks and vibrations (energy) arising due to the
coupling action of the coupling mechanism. Under the condition of
high temperatures, on the contrary, the transmission belt readily
absorbs the potential shocks and vibrations arising due to the
coupling action of the coupling mechanism. The arrangement of
varying the braking load by taking into account such conditions
attains both the requirement of absorbing potential shocks and
vibrations arising due to the coupling action of the coupling
mechanism and the requirement of quickly restarting the internal
combustion engine.
[0012] In one example of the above aspect that measures the
temperature of the transmission belt, the transmission belt
temperature measurement unit is a cooling fluid temperature
measurement unit that measures temperature of a cooling fluid
passing through the internal combustion engine. The braking load
specification unit determines the kinetic energy absorbing state of
the transmission belt based on the observed temperature of the
cooling fluid and increases the braking load with a decrease in
observed temperature of the cooling fluid. This arrangement enables
the temperature of the transmission belt to be obtained
indirectly.
[0013] In another aspect of this application, the transmission belt
temperature measurement unit is an engine velocity accumulation
unit that accumulates engine velocity or number of revolutions of
the internal combustion engine from a start to a stop of driving of
the internal combustion engine. In this aspect, the braking load
specification unit determines the kinetic energy absorbing state of
the transmission belt based on the accumulated engine velocity and
decreases the braking load with an increase in accumulated engine
velocity. In still another aspect of this application, the
transmission belt temperature measurement unit is an electric motor
velocity accumulation unit that accumulates electric motor velocity
or number of revolutions of the electric motor after a stop of
driving of the internal combustion engine. In this aspect, the
braking load specification unit determines the kinetic energy
absorbing state of the transmission belt based on the accumulated
electric motor velocity and decreases the braking load with an
increase in accumulated electric motor velocity. These arrangements
enable the temperature of the transmission belt to be obtained by
taking into account the frictional heat evolved due to the sliding
motions.
[0014] In either one of the above aspects, the transmission belt
temperature measurement unit further includes an outside air
temperature measurement unit that measures outside air temperature,
and the braking load specification unit increases a rate of
decrease of the braking load with an increase in observed outside
air temperature. This arrangement enables the temperature of the
transmission belt to be obtained by taking into account the outside
air temperature.
[0015] The present invention is also directed to a first vehicle
having an idling stop function to selectively stop and restart
driving an internal combustion engine according to a driving state
of the vehicle, wherein auxiliary machinery is driven by means of
an electric motor while the internal combustion engine is at a stop
and by means of the internal combustion engine while the internal
combustion engine is in active state. The first vehicle includes: a
coupling mechanism that links an output shaft of the internal
combustion engine with an output shaft of the electric motor, such
as to be coupled to connect the internal combustion engine with the
electric motor and to be released to disconnect the internal
combustion engine from the electric motor; a transmission belt that
is laid through the output shaft of the internal combustion engine,
an input shaft of the auxiliary machinery, and the output shaft of
the electric motor; a transmission belt state detection unit that
detects a kinetic energy absorbing state of the transmission belt;
and an idling stop control unit that specifies a rate of decrease
in electric motor velocity or number of revolutions of the electric
motor based on the detected kinetic energy absorbing state of the
transmission belt, and when a driving restart condition for
restarting operation of the internal combustion engine is
fulfilled, lowers the electric motor velocity by the specified rate
of decrease, causes the output shaft of the internal combustion
engine to be coupled with the output shaft of the electric motor
via the coupling mechanism, and subsequently carries out a series
of processing to restart driving the internal combustion
engine.
[0016] In the first vehicle of the present invention, the rate of
decrease in electric motor velocity is specified based on the
kinetic energy absorbing state of the transmission belt. This
arrangement effectively reduces or even omits potential shocks and
vibrations arising due to the coupling action of the coupling
mechanism at the time of starting the internal combustion engine,
and enables the vehicle to be quickly restored to the drivable
state.
[0017] In accordance with one preferable application of the first
vehicle of the present invention, the transmission belt state
detection unit detects the kinetic energy absorbing state of the
transmission belt based on elasticity of the transmission belt, and
the idling stop control unit enhances the rate of decrease in
electric motor velocity with a decrease in elasticity of the
transmission belt. In accordance with another preferable
application of the first vehicle of the present invention, the
transmission belt state detection unit detects the kinetic energy
absorbing state of the transmission belt based on temperature of
the transmission belt, and the idling stop control unit enhances
the rate of decrease in electric motor velocity with a decrease in
temperature of the transmission belt.
[0018] In one aspect of the above application that takes into
account the temperature of the transmission belt, the vehicle
further includes: a heat dissipation unit that is arranged on a
windward side of the transmission belt to dissipate heat of a
cooling fluid, which has passed through and cooled down the
internal combustion engine; and a cooling fluid temperature
measurement unit that measures temperature of the cooling fluid. In
this aspect, the transmission belt state detection unit calculates
the temperature of the transmission belt from the observed
temperature of the cooling fluid and detects the kinetic energy
absorbing state of the transmission belt based on the calculated
temperature of the transmission belt. In this structure, the
transmission belt is affected by the amount of heat dissipated by
the heat dissipation unit, that is, by the temperature of the
cooling fluid. Measurement of the temperature of the cooling fluid
thus enables the temperature of the transmission belt to be
obtained indirectly.
[0019] In another aspect of this application, the vehicle further
includes an engine velocity accumulation unit that accumulates
engine velocity or number of revolutions of the internal combustion
engine from a start to a stop of driving of the internal combustion
engine. In this aspect, the transmission belt state detection unit
calculates the temperature of the transmission belt from the
accumulated engine velocity and detects the kinetic energy
absorbing state of the transmission belt based on the calculated
temperature of the transmission belt. In still another aspect of
this application, the vehicle further includes an electric motor
velocity accumulation unit that accumulates electric motor velocity
or number of revolutions of the electric motor after a stop of
driving of the internal combustion engine. In this aspect, the
transmission belt state detection unit calculates the temperature
of the transmission belt from the accumulated electric motor
velocity and detects the kinetic energy absorbing state of the
transmission belt based on the calculated temperature of the
transmission belt. These arrangements enable the temperature of the
transmission belt to be obtained by taking into account the
frictional heat evolved due to the sliding motions.
[0020] In either one of the above aspects, the vehicle further
includes an outside air temperature measurement unit that measures
outside air temperature. The transmission belt state detection unit
calculates the temperature of the transmission belt from the
observed outside air temperature in addition to at least one of the
observed temperature of the cooling fluid, the accumulated engine
velocity, and the accumulated electric motor velocity and detects
the kinetic energy absorbing state of the transmission belt based
on the calculated temperature of the transmission belt. This
arrangement enables the temperature of the transmission belt to be
obtained by taking into account the outside air temperature.
[0021] In the first vehicle having any of the above configurations,
the idling stop control unit stops driving the internal combustion
engine and releases the coupling mechanism when a driving stop
condition of the internal combustion engine is fulfilled.
[0022] The present invention is further directed to a second
vehicle having an idling stop function to selectively stop and
restart driving an internal combustion engine according to a
driving state of the vehicle, wherein auxiliary machinery is driven
by means of an electric motor via a transmission belt while the
internal combustion engine is at a stop and by means of the
internal combustion engine while the internal combustion engine is
in active state. The second vehicle includes: a coupling mechanism
that links an output shaft of the internal combustion engine with
an output shaft of the electric motor, such as to be coupled to
connect the internal combustion engine with the electric motor and
to be released to disconnect the internal combustion engine from
the electric motor; a target braking velocity determination unit
that determines a target braking velocity for braking the electric
motor prior to a restart of driving of the internal combustion
engine by taking into account temperature of the transmission belt;
and an idling stop control unit that, when a driving restart
condition for restarting operation of the internal combustion
engine is fulfilled, drives the electric motor at the target
braking velocity, causes the output shaft of the internal
combustion engine to be coupled with the output shaft of the
electric motor via the coupling mechanism, and subsequently carries
out a series of processing to restart driving the internal
combustion engine.
[0023] In the second vehicle of the present invention, the target
braking velocity for braking the electric motor is determined by
taking into account the temperature of the transmission belt. This
arrangement effectively reduces or even omits potential shocks and
vibrations arising due to the coupling action of the coupling
mechanism at the time of starting the internal combustion engine,
and enables the vehicle to be quickly restored to the drivable
state.
[0024] In accordance with one preferable application of the present
invention, the second vehicle further includes: a heat dissipation
unit that is arranged on a windward side of the transmission belt
to dissipate heat of a cooling fluid, which has passed through and
cooled down the internal combustion engine; and a cooling fluid
temperature measurement unit that measures temperature of the
cooling fluid. In this application, the target braking velocity
determination unit takes into account the temperature of the
transmission belt based on the observed temperature of the cooling
fluid and lowers the target braking velocity with a decrease in
observed temperature of the cooling fluid. In this structure, the
transmission belt is affected by the amount of heat dissipated by
the heat dissipation unit, that is, by the temperature of the
cooling fluid. Measurement of the temperature of the cooling fluid
thus enables the temperature of the transmission belt to be taken
into account.
[0025] Like the first vehicle discussed above, in the second
vehicle of the present invention, the target braking velocity
determination unit takes into account the temperature of the
transmission belt based on the accumulated engine velocity or the
accumulated electric motor velocity, namely based on the frictional
heat evolved due to the sliding motions. The rate of increase in
target braking velocity may be varied according to the observed
outside air temperature.
[0026] In the second vehicle having any of the above
configurations, the idling stop control unit stops driving the
internal combustion engine and releases the coupling mechanism when
a driving stop condition of the internal combustion engine is
fulfilled.
[0027] The present invention is also directed to a method of
controlling idling stop in a vehicle that has an idling stop
function to selectively stop and restart driving an internal
combustion engine according to a driving state of the vehicle,
wherein auxiliary machinery is driven by means of an electric motor
while the internal combustion engine is at a stop. The method
includes the steps of: detecting a kinetic energy absorbing state
of a transmission belt that is laid through the internal combustion
engine, the electric motor, and the auxiliary machinery;
determining whether or not a driving restart condition for
restarting operation of the internal combustion engine is
fulfilled; when it is determined that the driving restart condition
is fulfilled, specifying a rate of decrease in electric motor
velocity or number of revolutions of the electric motor based on
the detected kinetic energy absorbing state of the transmission
belt; and lowering the electric motor velocity by the specified
rate of decrease and subsequently causing the output shaft of the
internal combustion engine to be coupled with the output shaft of
the electric motor via the coupling mechanism, so as to restart
driving the internal combustion engine.
[0028] In the method of the present invention, the rate of decrease
in electric motor velocity is specified based on the kinetic energy
absorbing state of the transmission belt. This arrangement
effectively reduces or even omits potential shocks and vibrations
arising due to the coupling action of the coupling mechanism at the
time of starting the internal combustion engine, and ensures a
quick restart of the internal combustion engine.
[0029] In accordance with one preferable application of the present
invention, the method further includes the steps of: measuring
elasticity of the transmission belt; detecting the kinetic energy
absorbing state of the transmission belt based on the observed
elasticity of the transmission belt; and enhancing the rate of
decrease in electric motor velocity with a decrease in observed
elasticity of the transmission belt. In accordance with another
preferable application of the present invention, the method further
includes the steps of: measuring temperature of the transmission
belt; detecting the kinetic energy absorbing state of the
transmission belt based on the observed temperature of the
transmission belt; and enhancing the rate of decrease in electric
motor velocity with a decrease in observed temperature of the
transmission belt. The kinetic energy absorbing state of the
transmission belt in the method is synonymous with the kinetic
energy absorbing state of the transmission belt in the idling stop
control apparatus of the present invention discussed above.
[0030] In one aspect of the above application that measures the
temperature of the transmission belt, the method further includes
the steps of: measuring temperature of a cooling fluid that passed
through the internal combustion engine; and enhancing the rate of
decrease in electric motor velocity with a decrease in observed
temperature of the cooling fluid. This arrangement enables the
temperature of the transmission belt to be obtained indirectly.
[0031] In another aspect of this application, the method further
includes the steps of: accumulating engine velocity or number of
revolutions of the internal combustion engine from a start to a
stop of driving of the internal combustion engine; and lowering the
rate of decrease in electric motor velocity with an increase in
accumulated engine velocity. In still another aspect of this
application, the method further includes the steps of: accumulating
electric motor velocity or number of revolutions of the electric
motor after a stop of driving of the internal combustion engine;
and lowering the rate of decrease in electric motor velocity with
an increase in accumulated electric motor velocity. These
arrangements enable the temperature of the transmission belt to be
obtained by taking into account the frictional heat evolved due to
the sliding motions.
[0032] In either one of the above aspects, the method further
includes the steps of: measuring an outside air temperature; and
enhancing the rate of decrease in electric motor velocity with an
increase in observed outside air temperature. This arrangement
enables the rate of decrease in electric motor velocity to be
varied according to the observed outside air temperature.
[0033] These and other objects, features, aspects, and advantages
of the present invention will become more apparent from the
following detailed description of the preferred embodiment with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1 is a block diagram schematically illustrating the
structure of a vehicle to which an idling stop control apparatus is
applied as one embodiment of the present invention;
[0035] FIG. 2 shows the arrangement of an engine, auxiliary
machinery, and an auxiliary machinery driving electric motor
mutually linked via a transmission belt in the embodiment;
[0036] FIG. 3 shows a control system adopted in the vehicle of the
embodiment;
[0037] FIG. 4 is a state transition diagram showing a series of
idling stop control process;
[0038] FIG. 5 is a flowchart showing a routine of controlling an
electromagnetic clutch executed at the time of restarting operation
of the engine;
[0039] FIG. 6 is a flowchart showing a routine of determining the
inverted phase current, which is to be input into the auxiliary
machinery driving electric motor, by taking into account the
temperature of the transmission belt;
[0040] FIG. 7 is a map used to specify a cooling fluid temperature
correction value Ew based on the temperature of the cooling fluid
passing through the engine;
[0041] FIG. 8 is a map used to specify an electric motor velocity
correction value Em based on the outside air temperature and the
accumulated electric motor velocity Nmsum of the auxiliary
machinery driving electric motor; and
[0042] FIG. 9 is a timing chart showing variations in coupling
timing of the electromagnetic clutch, the driving state of the
auxiliary machinery driving electric motor, the number of
revolutions of the damper or damper velocity, and the number of
revolution of a crankshaft or crankshaft velocity with time.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0043] An idling stop control apparatus embodying the present
invention is described below with referring to the drawings.
[0044] The description first regards the structure of a vehicle, on
which the idling stop control apparatus of the embodiment is
mounted, based on the illustrations of FIGS. 1 and 2. FIG. 1 is a
block diagram schematically illustrating the structure of a vehicle
to which the idling stop control apparatus of the embodiment is
applied. FIG. 2 shows the arrangement of an engine, auxiliary
machinery, and an auxiliary machinery driving electric motor
mutually linked via a transmission belt.
[0045] The vehicle includes an engine (internal combustion engine)
10 that functions as a power source, a torque converter 20 that
amplifies the output torque of the engine 10, and an automatic
transmission (AT) 22 that automatically varies the gear ratio
between a maximum gear ratio and a minimum gear ratio discretely.
The engine 10 is linked with a power input shaft of the torque
converter 20 via a crankshaft (output shaft) 11. A power output
shaft of the torque converter 20 is linked with a power input shaft
of the AT 22. A power output shaft of the AT 22 is linked with a
drive shaft 24. The drive shaft 24 is connected with wheels 27 via
a differential gear to (including a final gear) 25 and an axle
26.
[0046] The engine 10 is a direct injection gasoline engine, in
which a fuel (for example, gasoline) is directly injected into a
cylinder. The engine 10 has a high-pressure injector 12 to inject a
supply of gasoline into the cylinder and an ignition plug 13 to
ignite a gaseous mixture of the gasoline injected into the cylinder
and the intake air. A high-pressure supply of gasoline, which is
pressurized by a high-pressure fuel pump (not shown), is led into
the high-pressure injector 12. When the high-pressure injector 12
is activated to open in response to an injection signal output from
a control unit 60, the supply of gasoline is sprayed into the
cylinder. A high voltage is applied from an igniter 14 to the
ignition plug 13 in response to an ignition signal output from the
control unit 60. The engine 10 is provided with a cooling fluid
temperature sensor 50 that measures the temperature of a cooling
fluid used to cool down the engine 10. An outside air temperature
sensor 51 that measures the outside air temperature is disposed on
the front side of the engine 10 (that is, on the foreside of the
vehicle and on the left side in FIG. 1).
[0047] Referring to FIGS. 1 and 2, auxiliary machinery 30 including
a water pump 301, a compressor 302 for air conditioner, and a pump
303 for power steering and an auxiliary machinery driving electric
motor 31 used to drive the auxiliary machinery 30 while the engine
10 is at a stop by a series of idling stop control process are
arranged in the periphery of the engine 10. Pulleys 124 are
attached to the respective one ends of power input shafts of the
auxiliary machinery 301, 302, and 303, whereas a pulley 125 is
attached to one end of the crankshaft 11 of the engine 10. A
transmission belt 16 is spanned between the pulley 125 of the
engine 10 and a pulley 126 of the auxiliary machinery driving
electric motor 31 to start the engine 10 by means of the auxiliary
machinery driving electric motor 31. The pulley ratio of the pulley
125 to the pulley 126 is generally in the range between 1 to 2 and
1 to 3. A transmission belt 17 is laid along the pulleys 124 and
125. The output of the engine 10 is transmitted to the respective
power input shafts of the auxiliary machinery 30 via the
transmission belt 17, while the output of the auxiliary machinery
driving electric motor 31 is transmitted to the respective power
input shafts of the auxiliary machinery 30 via the transmission
belts 16 and 17. The transmission belts 16 and 17 may be V-shaped
belts having a trapezoidal cross section or V rib belts that are
thinner and wider than the V-shaped belts and have a plurality of
V-shaped grooves along the direction of rotations. The material of
the transmission belts 16 and 17 varies its shock- and
vibration-absorbing properties, depending upon the temperature. A
radiator 18 is disposed in front of (that is, on the windward side
of) the transmission belts 16 and 17 to dissipate the heat of the
cooling fluid that has passed through the engine 10.
[0048] A wet multi-plate electromagnetic clutch 15 is interposed
between the crankshaft 11 and the pulley 125. The electromagnetic
clutch 15 has a clutch plate 151 and a fly wheel 152. The
electromagnetic clutch 15 may be provided separately from the
pulley 125 as shown in FIG. 1 or alternatively be incorporated in
the pulley 125. The electromagnetic clutch 15 connects and
disconnects the power transmission between the crankshaft 11 and
the transmission belt 16. The electromagnetic clutch 15 includes a
damper (not shown) to relieve potential shocks and vibrations
occurring at the time of coupling.
[0049] While the vehicle runs or while the vehicle stops in the
active state of the engine 10, the electromagnetic clutch 15 is
coupled to transmit the driving force of the crankshaft 11 via the
transmission belt 17. The water pump 301, the compressor 302 for
air conditioner, and the pump 303 for power steering are
accordingly driven by means of the engine 10. While the engine 10
is at a stop by the series of idling stop control process, on the
other hand, the electromagnetic clutch 15 is released to
mechanically separate the crankshaft 11 from the transmission belt
17 (that is, from the pulley 125). The water pump 301, the
compressor 302 for air conditioner, and the pump 303 for power
steering are accordingly driven by the auxiliary machinery driving
electric motor 31 via the transmission belt 16 and the pulley 125.
Under such conditions, the crankshaft 11 is mechanically separated
from the pulley 125 and the transmission belts 16 and 17. The
auxiliary machinery driving electric motor 31 is thus not required
to drive the crankshaft 11. This arrangement desirably relieves the
loading applied to the auxiliary machinery driving electric motor
31.
[0050] The auxiliary machinery driving electric motor 31 is a
three-phase electric motor that has three-phase coils on a stator
and functions as the driving source to drive the crankshaft 11 at
the time of restarting the engine 10 as well as the driving source
to drive the auxiliary machinery 30. The auxiliary machinery
driving electric motor 31 also functions as an alternator that is
driven by the engine 10 in the active state to generate electric
power. The auxiliary machinery driving electric motor 31 is driven
and controlled by an inverter 200 in response to a driving signal
output from the control unit 60. The inverter 200 is connected to a
high voltage battery 210 and a DC-DC converter 220. The high
voltage battery 210 is specifically used as the power source to
drive the auxiliary machinery driving electric motor 31. While the
auxiliary machinery driving electric motor 31 works as the
alternator, the generated electric power is stored in the high
voltage battery 210. The DC-DC converter 220 is connected to the
control unit 60 to lower the voltage of the high voltage battery
210 or the voltage of the electric power generated by the auxiliary
machinery driving electric motor 31 and thereby charge a battery
230. The battery 230 is used as the power source to drive a starter
electric motor 41, an oil pump driving electric motor 45, and the
control unit 60 (all discussed later). The structure of this
embodiment includes both the high voltage battery 210 to drive the
auxiliary machinery driving electric motor 31 and the battery 230
to drive the control unit 60 and the other electric motors 41 and
45. A modified structure may include only the high voltage battery
210 and supply the electric power of the lowered voltage via the
DC-DC converter 220 to the control unit 60 and the other electric
motors 41 and 45.
[0051] A starter ring gear 40 linked with the crankshaft 11 is
interposed between the engine 10 and the torque converter 20. A
gear of the starter electric motor 41 is arranged to allow
engagement with the starter ring gear 40. The starter electric
motor 41 uses the battery 230 as the power source and drives and
rotates the engine 10 only at the time of starting the engine 10 in
response to an operation of an ignition switch (not shown), that
is, at the time of starting the engine 10 except the occasions of
restarting the engine 10 in the series of idling stop control
process. The gear of the starter electric motor 41 engages with the
starter ring gear 40 only at the time of starting the engine 10
under the condition that an ignition position sensor 58 detects a
change of the ignition position from ON to STA. The gear of the
starter electric motor 41 otherwise disengages from the starter
ring gear 40 but is kept at a separate stand-by position. As
mentioned previously, the auxiliary machinery driving electric
motor 31 functions as the starter electric motor at the time of
restarting the engine 10 in the series of idling stop control
process. In the structure of the embodiment, at the time of
starting the operation of the engine 10 (that is, at the first time
of starting the engine 10), the starter electric motor 41 is in
charge of starting the engine 10. At the time of restarting the
operation of the engine 10, the auxiliary machinery driving
electric motor 31 is in charge of starting the engine 10. The
starter electric motor 41 starts the engine 10 via the ring gear 40
that naturally causes gear noise. The gear noise makes a
significant problem in the case of frequent repetition of the
starting operation. Another potential problem under the idling stop
control process is wear of the gear due to the frequent repetition
of the starting operation. The auxiliary machinery driving electric
motor 31 is linked with the crankshaft 11 via the transmission belt
16. The crankshaft 11 may thus not be driven or rotated under the
condition of high viscosity of a lubricant, for example, in the
cold and may fail to start the engine 10. At the first time of
starting the engine 10, the starter electric motor 41 is
accordingly used to start the engine 10. At the time of restarting
the engine 10, the auxiliary machinery driving electric motor 31 is
used to start the engine 10.
[0052] The torque converter 20 is a general fluid torque converter,
which amplifies the driving torque input into the input shaft and
outputs the amplified torque from the output shaft. The detailed
structure and functions of the torque converter are well known in
the art and are thus not specifically described here. The automatic
transmission (AT) 22 includes a planetary gear and automatically
varies the gear combination via a hydraulic actuator (not shown)
according to the vehicle speed and the step-on amount of the
accelerator pedal, so as to change the gear ratio. The output shaft
of the AT 22 is linked with the drive shaft 24, and the driving
force output from the output shaft of the AT 22 is transmitted to
the wheels 27 via the drive shaft 24, the differential gear 25, and
the axle 26. The oil pump driving electric motor 45 is disposed in
the vicinity of the AT 22 to keep the hydraulic pressure of the
driving system even during a stop of the engine 10. The oil pump
driving electric motor 45 is driven with the battery 230 as the
power source.
[0053] The control system of the vehicle in this embodiment is
described below with referring to FIG. 3. FIG. 3 shows the control
system adopted in the vehicle of the embodiment. The control unit
60 includes an idling stop ECU (electronic control unit) 600, an
engine ECU 610, and a brake ECU 620. Each of the ECUs 600, 610, and
620 includes a CPU, a ROM, a RAM, and other related elements. These
ECUs are only illustrative. For example, an ECU for controlling the
AT 22 may be separate from the idling stop ECU 600.
[0054] The idling stop ECU 600 is mainly in charge of the idling
stop control carried by the control unit 60. The idling stop ECU
600 is connected to the engine ECU 610 and the brake ECU 620 via
signal lines to allow mutual communications. The idling stop ECU
600 connects via signal lines with a cooling fluid temperature
sensor 50 that measures the temperature of an engine cooling fluid,
an outside air temperature sensor 51 that measures the temperature
of the outside air, an electric motor velocity sensor 52 that
measures the number of revolutions or velocity of the auxiliary
machinery driving electric motor 31, an engine velocity sensor 53
that measures the number of revolutions or velocity of the
crankshaft 11 of the engine 10, a vehicle speed sensor 54 that
measures the vehicle speed, a gearshift position sensor 55 that
detects the current gear position, an accelerator travel sensor 56
that specifies the position of the accelerator pedal as the
accelerator travel, a brake pedal sensor 57 that specifies the
step-on state of the brake pedal, and an ignition position sensor
58 that detects the position of the ignition switch. The idling
stop ECU 600 is also connected to the inverter 200, the starter
electric motor 41, the electromagnetic clutch 15, the DC-DC
converter 220, the oil pump driving electric motor 45, the AT 22,
and a gauge panel 46.
[0055] The idling stop ECU 600 regulates the velocity of the
auxiliary machinery driving electric motor 31 via the inverter 200,
so as to make the auxiliary machinery 30 driven while the engine 10
is at a stop by the idling stop control process. In order to
restart driving the engine 10 that is in the idling stop state, the
auxiliary machinery driving electric motor 31 drives and rotates
the crankshaft 11 of the engine 10 and raises the engine velocity
to a starting speed, instead of the starter electric motor 41. The
idling stop ECU 600 controls an electromagnetic actuator (not
shown) of the electromagnetic clutch 15 to couple and release the
clutch plate 151 with and from the fly wheel 152, thereby
controlling transmission and blockage of the power. The idling stop
ECU 600 controls the hydraulic actuator (not shown) based on the
data sent from the vehicle speed sensor 54, the gearshift position
sensor 55, and the accelerator travel sensor 56, and changes the
gear ratio at an optimum change speed point. Programs for executing
the idling stop control process of this embodiment are stored in
the ROM of the idling stop ECU 600.
[0056] The engine ECU 610 regulates the amount of fuel injection
via the injector 12 and controls the ignition timing via the
igniter 14 in response to a request from the idling stop ECU 600,
thereby controlling the driving conditions of the engine 10. While
the vehicle is at a stop according to the idling stop control
process, the engine ECU 610 ceases the fuel injection via the
injector 12 to the engine 10 in response to a request from the
idling stop ECU 600, so as to stop operation of the engine 10.
[0057] The brake ECU 620 is connected with a brake actuator 47 and
controls the brake actuator 47 to keep the brake hydraulic pressure
until the driving force of the engine 10 rises to a sufficient
level in the process of restarting the engine 10 that is in the
idling stop state. The state in which the driving force of the
engine 10 rises to the sufficient level means that the vehicle is
kept at a stop, for example, on a slope even when the brake pedal
is released.
[0058] General operations of the vehicle having the above
construction are discussed below with reference to FIGS. 1 through
3. When the ignition position sensor 58 detects a change of the
ignition position from ON to STA (the engine starting position)
while the gearshift lever is either in a parking position P or a
neutral position N, the idling stop ECU 600 causes the gear of the
starter electric motor 41 to engage with the ring gear 40 and
subsequently drives the starter electric motor 41 to rotate the
crankshaft 11 to the engine starting speed. The idling stop ECU 600
simultaneously requests the engine ECU 610 to carry out an engine
starting process. The engine ECU 610 causes a preset quantity of
the fuel to be supplied into the cylinder of the engine 10 via the
injector 12 and carries out the engine starting process that
ignites the fuel supplied into the engine cylinder via the igniter
14 and the ignition plug. When the engine 10 starts driving, the
gear of the starter electric motor 41 is separate from the ring
gear 40 and returned to its stand-by position. When the driver
shifts the gearshift lever to a drive position D and steps on the
accelerator pedal, the vehicle starts. The idling stop ECU 600 and
the engine ECU 610 then control operations of the engine 10 and the
change speed process of the AT 22, based on the data sent from, for
example, the engine velocity sensor 53, the vehicle speed sensor
54, and the accelerator travel sensor 56.
[0059] In the structure of this embodiment, the idling stop ECU 600
carries out the idling stop control process to stop driving the
engine 10 at a temporary stop of the vehicle, for example, at a
traffic light during a drive of the vehicle under predetermined
conditions. The details of the idling stop control process are
discussed below with reference to FIG. 4. FIG. 4 is a state
transition diagram showing a series of idling stop control
process.
[0060] When the ignition position sensor 58 detects a change of the
ignition position from OFF to ON, the idling stop ECU 600 selects a
mode `0` that represents the inactive state of the engine 10 by any
processing other than the idling stop control process. In the state
of mode `0`, an indicator lamp, which is lit during execution of
the idling stop control process, on the gauge panel 46 is off. When
the ignition position sensor 58 detects a change of the ignition
position from ON to STA, the starter electric motor 41 starts
driving the engine 10 as described previously. The idling stop ECU
600 here selects a mode `1` that represents the active state of the
engine 10. In the state of mode `1`, the vehicle is either in the
driving state or at a stop while the engine 10 continues driving.
In this state, the idling stop ECU 600 couples the electromagnetic
clutch 15 to link the crankshaft 11 with the transmission belt 17.
The auxiliary machinery 30 is thus driven by the driving force of
the engine 10. The auxiliary machinery driving electric motor 31 is
driven by the engine 10 via the transmission belt 16 and functions
as the alternator or is at an idle when the high-voltage battery
210 is in the full charge level.
[0061] When it is determined that predetermined conditions of the
idling stop control process are fulfilled, the idling stop ECU 600
selects a mode `2` that represents the transient state to stop
driving the engine 10. The predetermined conditions of the idling
stop control process include that the vehicle speed measured by the
vehicle speed sensor 54 is equal to zero, that the step-on of the
brake pedal is detected by the brake pedal sensor 57, and that
current gearshift position detected by the gearshift position
sensor 55 is the neutral position N. In the state of mode `2`, the
idling stop ECU 600 requests the engine ECU 610 to stop the fuel
supply. The idling stop ECU 600 also request the brake ECU 620 to
keep the braking state. The brake ECU 620 regulates the brake
actuator 47 and keeps the brake hydraulic pressure corresponding to
the step-on amount of the brake pedal.
[0062] When it is determined that the engine 10 is at a stop, based
on the data sent from the engine velocity sensor 53, the idling
stop ECU 600 selects a mode `3` that represents the inactive state
of the engine 10 by the idling stop control process. In the state
of mode `3`, the idling stop ECU 600 lights on the indicator lamp
on the gauge panel 46 to show the execution of the idling stop
control process. The idling stop ECU 600 also releases the
electromagnetic clutch 15 to disconnect the crankshaft 11 from the
transmission belts 16 and 17 and causes the auxiliary machinery
driving electric motor 31 to drive the respective auxiliary
machinery 301, 302, and 303 via the transmission belt 17.
[0063] In response to detection of a request to terminate the
idling stop control process, the idling stop ECU 600 selects a mode
`4` that represents the engine starting control state to restart
driving the engine 10. The idling stop ECU 600 detects the request
to terminate the idling stop control process, for example, when the
gearshift lever is shifted from the neutral position N to the drive
position D, when the brake pedal is released, when the charging
rate of the battery becomes lower than a lower limit or a charging
requirement level, when the air conditioner has insufficient
cooling performances, and when some system trouble occurs. In the
state of mode `4`, the idling stop ECU 600 brakes the auxiliary
machinery driving electric motor 31 to reduce the number of
revolutions or velocity of the auxiliary machinery driving electric
motor 31, prior to the coupling of the electromagnetic clutch 15.
The idling stop ECU 600 couples the electromagnetic clutch 15 at a
coupling timing determined by an electromagnetic clutch coupling
timing delay process (discussed later) and subsequently raises the
velocity of the auxiliary machinery driving electric motor 31 to
the engine starting speed. The idling stop ECU 600 also requests
the engine ECU 610 to carry out the fuel supply and spark ignition.
In response to detection of any serious system trouble that leads
to failure of driving, the idling stop ECU 600 selects the mode
`0`.
[0064] In response to detection of a start of the engine 10, the
idling stop ECU 600 selects the mode `1`. The idling stop ECU 600
determines that the engine 10 is at a start, for example, when the
engine velocity measured by the engine velocity sensor 53 is not
less than 500 rpm. The idling stop ECU 600 here requests the brake
ECU 620 to release the sustained brake hydraulic pressure. The
brake ECU 620 regulates the brake actuator 47 to release the
sustained brake hydraulic pressure and sets the non-braking state.
In the state of mode `1`, when the ignition position sensor 58
detects a change of the ignition position from ON to OFF, the
idling stop ECU 600 selects the mode
[0065] The following describes a series of processing to control
the electromagnetic clutch 15 and the auxiliary machinery driving
electric motor 31, which is executed at the time of restarting
operation of the engine 10 in this embodiment, with referring to
FIGS. 5 through 9. FIG. 5 is a flowchart showing a processing
routine of controlling the electromagnetic clutch 15 and the
auxiliary machinery driving electric motor 31, which is executed at
the time of restarting operation of the engine 10. FIG. 6 is a
flowchart showing a routine of determining the quantity of power
generation (the inverted phase current) of the auxiliary machinery
driving electric motor 31 by taking into account the temperature of
the transmission belt 16. FIG. 7 is a map used to specify a cooling
fluid temperature correction value Ew based on the temperature of
the cooling fluid passing through the engine 10. FIG. 8 is a map
used to specify an electric motor velocity correction value Em
based on the outside air temperature and the accumulated electric
motor velocity Nmsum of the auxiliary machinery driving electric
motor 31. FIG. 9 is a timing chart showing variations in coupling
timing of the electromagnetic clutch 15, the driving state of the
auxiliary machinery driving electric motor 31, the number of
revolutions of the electromagnetic clutch 15 (damper) or damper
velocity, and the number of revolution of the crankshaft 11 or
crankshaft velocity with time.
[0066] The processing routine of FIG. 5 is executed at preset time
intervals. When the program enters this processing routine, the
idling stop ECU 600 first determines whether or not a request is
given to terminate the idling stop control process (that is, an
engine restart request) at step S100. Namely the idling stop ECU
600 determines whether a restart request signal is changed from OFF
to ON in the timing chart of FIG. 9. When there is no engine
restart request, that is, in the case of negative answer at step
S100, the idling stop ECU 600 immediately exits from this
processing routine. When there is an engine restart request, that
is, in the case of affirmative answer at step S100, on the other
hand, the idling stop ECU 600 determines an inverted phase current
Eon, which is to be supplied to the auxiliary machinery driving
electric motor 31, at step S110. In accordance with a concrete
procedure, the process of step S110 specifies the magnitude of the
braking force (the reverse torque) of the auxiliary machinery
driving electric motor 31 by taking into account the energy
absorbing state of the transmission belt 16. The detailed process
of determining the inverted phase current Eon will be discussed
later with reference to FIGS. 6 through 8.
[0067] The idling stop ECU 600 then drives the auxiliary machinery
driving electric motor 31 at the predetermined inverted phase
current Eon at step S120. As a result, the reverse torque arises in
the auxiliary machinery driving electric motor 31 to interfere with
its rotations and reduce the number of revolutions or velocity of
the auxiliary machinery driving electric motor 31. The idling stop
ECU 600 subsequently couples the electromagnetic clutch 15 at step
S130 and exits from this processing routine.
[0068] Referring to the timing chart of FIG. 9, after the restart
request signal is changed from OFF to ON and the braking operation
of the auxiliary machinery driving electric motor 31 starts, an
electromagnetic clutch control signal is set ON to start suction of
the clutch plate 151 by means of the magnetic force (clutch
suction). In the transient state between a start of coupling
(contact) of the clutch plate 151 with the fly wheel 152 and
completion of the coupling, the electromagnetic clutch 15 is in the
slipping state. In this state, the electromagnetic clutch 15
(damper) has the lowered number of revolutions or velocity, while
the velocity of the crankshaft 11 starts rising. When the coupling
of the clutch plate 151 with the fly wheel 152 is completed, the
velocity of the electromagnetic clutch 15 is equal to the velocity
of the crankshaft 11. On completion of the coupling of the
electromagnetic clutch 15, the auxiliary machinery driving electric
motor 31 rotates the crankshaft 11 to the engine starting speed, in
order to start the engine 10. The engine ECU 610 then carries out
the engine starting process. When explosion and combustion starts
in any cylinder of the engine 10 (initial explosion), the auxiliary
machinery driving electric motor 31 is driven by the engine 10 to
generate electric power or to be at an idle.
[0069] The following describes the detailed process of determining
the inverted phase current Eon with referring to FIGS. 6 through 8.
The absorbing state of the kinetic energy (shocks and vibrations)
of the transmission belt 16 depends upon the temperature. Direct
measurement of the temperature of the transmission belt 16 is
accordingly the best way to determine the kinetic energy absorbing
state of the transmission belt 16. It is, however, difficult to
come in direct contact with the moving transmission belt 16 and
measure its temperature. The technique of this embodiment thus
indirectly determines the kinetic energy absorbing state
(temperature) of the transmission belt 16 according to the
following procedure. In this embodiment, the temperature of the
transmission belt 16 does not mean the absolute temperature of the
transmission belt 16 but represents the relative temperature of the
transmission belt 16 relative to variations in cooling fluid
temperature Tempw and in accumulated electric motor velocity Nmsum,
which are related in advance. The temperature of the transmission
belt 16 may be measured directly by means of an infrared sensor or
another suitable means as described later.
[0070] When the program enters the processing routine of FIG. 6,
the idling stop ECU 600 first obtains the cooling fluid temperature
Tempw from the cooling fluid temperature sensor 50 at step S200 and
reads a cooling fluid temperature correction value Ew mapped to the
input cooling fluid temperature Tempw from the map of FIG. 7 at
step S210. The transmission belt 16 is generally located behind the
radiator 18 and is exposed to the blast passing through the
radiator 18. The temperature of the transmission belt 16
accordingly varies in proportion to a variation in temperature of
the radiator 18 (that is, the cooling fluid temperature Tempw). The
cooling fluid temperature Tempw is thus used as the indication of
the temperature of the transmission belt 16. As shown in the map of
FIG. 7, the cooling fluid temperature correction value Ew is
related to the cooling fluid temperature Tempw and is used as a
base value to determine the coupling timing. In the map of FIG. 7,
the rate of change in cooling fluid temperature correction value Ew
varies at a thermostat on temperature of the radiator 18, for
example, approximately 80.degree. C. In the temperature range close
to the temperature of completing the warm-up of the engine 10, the
temperature of the transmission belt 16 has reached a specific
temperature range, in which the sufficient energy absorption is
expected. The rate of decrease in cooling fluid temperature
correction value Ew is accordingly enhanced in this temperature
range.
[0071] The idling stop ECU 600 subsequently obtains the accumulated
electric motor velocity Nmsum at step S220. The accumulated
electric motor velocity Nmsum represents the accumulated number of
revolutions of the auxiliary machinery driving electric motor 31
during a time period between a start of rotations of the auxiliary
machinery driving electric motor 31 after the stop of the engine 10
by the idling stop control process and a start of the braking
operation. The temperature of the transmission belt 16 is basically
proportional to the temperature of the blast passing through the
radiator 18 (that is, the cooling fluid temperature Tempw), but may
rise independently of the cooling fluid temperature Tempw during
rotations by means of the frictional heat caused by friction of the
transmission belt 16 against the pulleys 125 and 126. The
temperature rise of the transmission belt 16 by means of the
frictional heat is proportional to the accumulated number of
revolutions of the auxiliary machinery driving electric motor 31.
The accumulated electric motor velocity Nmsum is accordingly used
as the indication of the temperature rise of the transmission belt
16 by means of the frictional heat. The outside air temperature
also affects the temperature rise of the transmission belt 16 by
means of the frictional heat. The idling stop ECU 600 accordingly
obtains the outside air temperature Tempo from the outside air
temperature sensor 51 at step S230. The high outside air
temperature accelerates the temperature rise of the transmission
belt 16. The low outside air temperature, on the other hand,
interferes with the temperature rise of the transmission belt 16.
The idling stop ECU 600 reads an electric motor velocity correction
value Em mapped to the input accumulated electric motor velocity
Nmsum and the input outside air temperature Tempo from the map of
FIG. 8 at step S240. In this embodiment, the electric motor
velocity correction value Em monotonously decreases in proportion
to an increase in accumulated electric motor velocity Nmsum. The
map of FIG. 8 shows three characteristic curves with regard to the
variation in outside air temperature, that is, the low temperatures
(for example, lower than 0.degree. C.), the intermediate
temperatures (for example, not lower than 0.degree. C. but lower
than 30.degree. C.), and the high temperatures (for example, not
lower than 30.degree. C.). The electric motor velocity correction
value Em increases with a decrease in outside air temperature Tempo
with regard to an identical accumulated electric motor velocity
Nmsum. The idling stop ECU 600 calculates the inverted phase
current Eon as the sum of the cooling fluid temperature correction
value Ew and the electric motor velocity correction value Em at
step S250, and returns to the processing routine of FIG. 5.
[0072] The following describes the effects of the braking control
of the auxiliary machinery driving electric motor 31 (the
regulation of the amount of power generation) discussed above with
referring to the timing chart of FIG. 9. In the timing chart of
FIG. 9, the solid curves represent the case of no enhancement of
the braking force (including the prior art) except the restart
request signal. The broken curves represent the case of enhancement
of the braking force (at the time of delay). It is here assumed
that an identical axis of revolution is applied for the crankshaft
velocity and the electromagnetic clutch velocity.
[0073] When the braking force is enhanced with a decrease in
temperature of the transmission belt 16, the greater force is
applied to brake the rotations of the auxiliary machinery driving
electric motor 31 (that is, the greater amount of power generation
and the greater inverted phase current). This leads to a large rate
of decrease in velocity of the auxiliary machinery driving electric
motor 31. At the time of starting the coupling of the
electromagnetic clutch 15 to be in the clutch slipping state, the
velocity of the electromagnetic clutch 15 under the enhanced
braking force is reduced by approximately 60 to 70%, compared with
the case of no enhancement of the braking force. This represents
the difference in velocity under the coupled clutch. This decreases
the difference in velocity between the crankshaft 11 and the
electromagnetic clutch 15 and accordingly relieves the potential
shocks and vibrations arising due to the coupling of the
electromagnetic clutch 15. This arrangement results in the low
energy of causing vibrations and shocks and thus relieves the
potential shocks and vibrations transmitted to the vehicle body
even when the temperature of the transmission belt 16 is relatively
low to only insufficiently absorb the kinetic energy thereof. The
inverted phase current Eon is varied according to the kinetic
energy state of the transmission belt 16 (that is specified by the
temperature as the indication). In the case where the transmission
belt 16 can absorb the shocks and vibrations arising due to the
coupling of the electromagnetic clutch 15, the coupling timing is
advanced to give the preference to the starting ability of the
engine 10.
[0074] In the case where the braking force of the auxiliary
machinery driving electric motor 31 is fixed irrespective of the
temperature of the transmission belt 16, the greater braking force
applied to the auxiliary machinery driving electric motor 31 by
taking into account the cold time lowers the velocity of the
auxiliary machinery driving electric motor 31 below the required
level and delays the time required for restarting the engine 10
even under the condition of the high temperatures of the
transmission belt 16. The smaller braking force applied to the
auxiliary machinery driving electric motor 31 by giving the
preference to the starting ability of the engine 10, on the other
hand, causes the shocks and vibrations to be transmitted to the
vehicle body especially when the temperature of the transmission
belt 16 is relatively low to only insufficiently absorb the kinetic
energy thereof.
[0075] The idling stop control apparatus of the present invention
is described above with the preferred embodiment. The above
embodiment is to be considered in all aspects as illustrative and
not restrictive. There may be many modifications, changes, and
alterations without departing from the scope or spirit of the main
characteristics of the present invention. All changes within the
meaning and range of equivalency of the claims are therefore
intended to be embraced therein.
[0076] For example, in the structure of the embodiment where the
transmission belts 16 and 17 are located behind the radiator 18,
the temperature (the energy absorbing state) of the transmission
belt 16 is specified based on the cooling fluid temperature of the
engine 10. In a modified structure where the transmission belts 16
and 17 are located on the surface of the radiator 18, the
temperature of the transmission belt 16 may be specified based on
the outside air temperature measured by the outside air temperature
sensor 51. The kinetic energy absorbing state of the transmission
belt 16 may be detected by non-contact means. For example, the
temperature of the transmission belt 16 may be measured with a
non-contact temperature sensor, for example, a thermocouple or an
infrared sensor. Another applicable procedure measures the
temperature of either one of the pulleys 125 and 126 that are in
contact with the transmission belt 16, so as to specify the
temperature of the transmission belt 16.
[0077] The technique of the embodiment specifies the temperature
rise of the transmission belt 16 by means of the frictional heat
based on the accumulated electric motor velocity Nmsum, which
represents the accumulated number of revolutions of the auxiliary
machinery driving electric motor 31 since the starting time of
driving the auxiliary machinery 30. The accumulated velocity of the
crankshaft 11 until an end of operation of the engine 10 may be
used instead of the accumulated electric motor velocity Nmsum. Both
the accumulated velocities can be used as the indication to
estimate the temperature rise due to the friction of the
transmission belt 16 against the respective pulleys 125 and
126.
[0078] In the structure of the embodiment, the damper is included
in the electromagnetic clutch 15. The damper may alternatively be
provided separately from the electromagnetic clutch 15. For
convenience of explanation, the crankshaft pulley 125 and the
electromagnetic clutch 15 are illustrated as separate elements in
FIG. 1. The electromagnetic clutch 15 may, however, be incorporated
in the crankshaft pulley 125.
[0079] The automatic transmission (AT) 22 used in the embodiment
may be replaced by a manual transmission or an automatic continuous
transmission. The structure using either of such alternative
transmissions enables execution of the idling stop control process
discussed above and exerts the similar effects to those of the
embodiment using the automatic transmission.
[0080] The above embodiment regards the vehicle having only the
engine 10 as the power source of the vehicle. The technique of the
present invention is also applicable to a hybrid vehicle having
both the engine 10 and a vehicle driving electric motor as the
driving source. In the hybrid vehicle, the auxiliary machinery 30
is driven by means of the auxiliary machinery driving electric
motor 31 during the execution of the idling stop control process.
At the time of restarting the engine 10, the electromagnetic clutch
15 is coupled to link the rotor of the auxiliary machinery driving
electric motor 31 with the crankshaft 11 of the engine 10 and
thereby start driving the engine 10. Application of the present
invention effectively reduces or even omits the potential shocks
and vibrations arising due to the coupling of the electromagnetic
clutch 15.
[0081] The scope and spirit of the present invention are indicated
by the appended claims, rather than by the foregoing
description.
* * * * *