U.S. patent application number 09/784037 was filed with the patent office on 2001-08-16 for warm-up control device of hybrid electric vehicle.
Invention is credited to Ogata, Makoto, Yanase, Takashi.
Application Number | 20010013702 09/784037 |
Document ID | / |
Family ID | 18562314 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010013702 |
Kind Code |
A1 |
Yanase, Takashi ; et
al. |
August 16, 2001 |
Warm-up control device of hybrid electric vehicle
Abstract
The invention provides a warm-up control device of a hybrid
electric vehicle, which warms up an engine for generator while
extending the life of the engine and improves the quietness. If an
engine temperature is not greater than a set temperature after the
start of the engine for generator, the warm-up control device
controls a load of the generator and controls an engine output in
accordance with the load of the generator so as to maintain an
engine revolution speed at a predetermined low revolution
speed.
Inventors: |
Yanase, Takashi; (Kanagawa,
JP) ; Ogata, Makoto; (Kanagawa, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
18562314 |
Appl. No.: |
09/784037 |
Filed: |
February 16, 2001 |
Current U.S.
Class: |
290/40C ;
180/65.245; 180/65.27; 180/65.28; 180/65.285; 290/40B; 290/40R;
903/903 |
Current CPC
Class: |
F02D 41/068 20130101;
B60W 10/08 20130101; Y02T 10/70 20130101; B60L 2220/12 20130101;
B60K 6/46 20130101; F02D 2041/026 20130101; B60L 2240/445 20130101;
Y02T 10/62 20130101; B60W 2710/0644 20130101; Y10S 903/903
20130101; B60W 20/00 20130101; B60L 50/61 20190201; B60W 2510/0676
20130101; B60L 50/62 20190201; B60L 2220/14 20130101; B60L 2240/441
20130101; B60W 10/06 20130101; B60L 2270/145 20130101; Y02T 10/7072
20130101; F02D 41/083 20130101 |
Class at
Publication: |
290/40.00C ;
290/40.00B; 290/40.00R |
International
Class: |
H02P 009/04; F02N
011/06 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 16, 2000 |
JP |
2000-38602 |
Claims
What is claimed is:
1. A hybrid electric vehicle comprising: a generator being rotated
by a driving force of an engine to generate power and supply the
power to a battery or a motor; a temperature sensing device for
sensing a temperature of said engine; and a warm-up control device
for controlling a load of said generator and an output of said
engine so as to maintain a revolution speed of said engine at a
predetermined revolution speed, if the temperature of said engine
sensed by said temperature sensing device is not greater than a set
temperature.
2. A hybrid electric vehicle according to claim 1, wherein: said
warm-up control device changes the load of said generator according
to the temperature sensed by said temperature sensing device.
3. A hybrid electric vehicle according to claim 1, wherein: said
warm-up control device increases the load of said generator as the
temperature sensed by said temperature sensing device is
lowered.
4. A hybrid electric vehicle according to claim 1, wherein: said
warm-up control device has a first set load and a second set load
higher than said first set load in order to change the load of said
generator, and determines which of said set loads is to be applied
to said generator according to the temperature sensed by said
temperature sensing device.
5. A hybrid electric vehicle according to claim 4, wherein: if the
temperature sensed by said temperature sensing device is higher
than a first predetermined temperature lower than said set
temperature, said warm-up control device changes the load of said
generator to said first set load; and if the temperature sensed by
said temperature sensing device is lower than said first
predetermined temperature, said warm-up control device changes the
load of said generator to said second set load.
6. A hybrid electric vehicle according to claim 1, wherein: said
warm-up control device finishes controlling the load of said
generator and the output of said engine when the temperature sensed
by said temperature sensing device exceeds a second preset
temperature higher than said set temperature.
7. A hybrid electric vehicle comprising: a generator being rotated
by a driving force of an engine to generate power and supply the
power to a battery or a motor; and a warm-up control device for
increasing a load of said generator and controlling an output of
said engine so as to maintain a revolution speed of said engine at
a predetermined revolution speed after starting said engine in a
cold state.
8. A method for warming up an engine from a cold state in a hybrid
drive system wherein the engine drives an electric generator,
comprising the steps of: sensing a condition indicative of said
engine being in a cold state; starting said engine and bringing the
revolution speed of said engine to a predetermined minimum level;
placing a predetermined load on said generator; and maintaining
said predetermined minimum level of revolution speed on said engine
against said predetermined load on said generator to reduce time
and engine noise associated with engine warm-up.
9. The method of claim 8, including the further steps of sensing a
second condition indicative of a warmed-up state of said engine;
and removing the constraints placed upon said engine revolution
speed and generator load during engine warm-up.
10. The method of claim 8, wherein said engine has a plurality of
cold states; and said generator has a like plurality of loads
selectively associated with a respective cold state to optimize the
warm-up of said engine.
Description
BACKGROUND OF THE INVENTION
[0001] Applicant's hereby claim the right of priority, under 35
U.S.C. .sctn. 119, based on Japanese Application No. 2000-38602,
filed on Feb. 16, 2000, the entire contents of which are hereby
incorporated by reference.
[0002] 1. Field of the Invention
[0003] The present invention generally relates to a hybrid electric
vehicle, and more particularly to a technique for warming up an
engine for driving a generator in such a vehicle.
[0004] 2. Description of Related Art
[0005] In recent years, there has been developed a series hybrid
vehicle, that is a vehicle equipped with a motor as a source of
driving force for the vehicle and a secondary battery, which
supplies power to the motor, that is charged by a generator driven
by a relatively-small engine. Normally, the series hybrid vehicle
operates the engine to run the generator in order to charge the
battery if a charging level (SOC: state of charge) of the battery
is low.
[0006] In general, the series hybrid vehicle, however, does not
always charge the battery while the vehicle is running, but charges
the battery if the engine is cold after being static for a long
period of time. Therefore, if the engine is cold and a large amount
of power is required to be generated, the forcible increase in an
engine output increases fuel consumption causing a deterioration in
fuel economy and also increases oil consumption. This shortens the
life of the engine.
[0007] To address this problem, Japanese Patent Provisional
Publication No. 5-328528 discloses a device, which raises an engine
revolution speed to warm up an engine used to drive a generator
when the engine is cold.
[0008] The rise in the engine revolution speed as disclosed in the
above publication, however, results in the increase in noise and
vibration. Moreover, if the engine is cold and is not completely
smooth, the rise in the engine revolution speed results in the
damage on each sliding part of the engine. The increase in the
noise and vibration and the damage on each sliding part shorten the
life of the engine.
SUMMARY OF THE INVENTION
[0009] It is therefore an object of the present invention to
provide a warm-up control device of a hybrid electric vehicle,
which warms up an engine used to drive a generator while extending
the life of the engine and improving the quietness.
[0010] The above object can be accomplished by providing a hybrid
electric vehicle comprising: a generator being rotated by a driving
force of an engine to generate power and supply the power to a
battery or a motor; a temperature sensing device for sensing a
temperature of the engine; and a warm-up control device for
controlling a load of the generator and an output of the engine so
as to maintain a revolution speed of the engine at a predetermined
revolution speed, if the temperature of the engine sensed by the
temperature sensing device is not greater than a set
temperature.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The nature of this invention, as well as other objects and
advantages thereof, will be explained in the following with
reference to the accompanying drawings, in which like reference
characters designate the same or similar parts throughout the
figures and wherein:
[0012] FIG. 1 is a schematic diagram showing a series hybrid
vehicle, to which a warm-up control device of a hybrid electric
vehicle according to the present invention is applied;
[0013] FIG. 2 is a flow chart showing a control routine of a
warm-up control according to the present invention; and
[0014] FIG. 3 is a drawing showing a relationship between a
generator revolution speed Ng (=Ne) and a generated torque Tg,
i.e., load, and showing a relationship between a load equivalent to
a small power generation (the first set load Tg1: black circle) and
a load equivalent to a medium power generation (the second set load
Tg2: white circle).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0015] A preferred embodiment of the present invention will be
described hereinbelow.
[0016] FIG. 1 is a schematic diagram showing a series hybrid
vehicle, to which a warm-up control device of a hybrid electric
vehicle according to the present invention is applied. With
reference to FIG. 1, there will now be described the structure of
the warm-up control device of the hybrid electric vehicle according
to the present invention. For example, a large vehicle such as an
omnibus, which runs at a low speed in a city, can be such a series
hybrid vehicle.
[0017] As shown in FIG. 1, the series hybrid vehicle is equipped
with a traction motor 10 as a source of driving force. The traction
motor 10 is electrically connected to a high-voltage secondary
battery 12, which supplies power, through a first inverter 14. The
traction motor 10 is an induction motor, but may also be a
permanent electromagnet synchronous type motor.
[0018] When the vehicle is braked, the traction motor 10 functions
as an energy regenerative brake, i.e., a generator that utilizes
braking energy. More specifically, when a driver of the vehicle
operates a brake (not shown), the traction motor 10 generates a
braking force and power at the same time. The generated power is
charged in the battery 12. The first inverter 14 supplies stable
power to the traction motor 10 by adjusting a voltage and a current
supplied from the battery 12 or a later-described generator 22, or
supplies stable power to the battery 12 by adjusting a voltage and
a current generated by the traction motor 10.
[0019] As shown in FIG. 1, a pair of driving wheels WR, WL is
connected to a rotary shaft of the traction motor 10 through
reduction gears 16 and a differential gear 18. The reduction gears
16 are not necessarily always provided. The battery 12 and the
first inverter 14 are electrically connected to the generator 22
through a second inverter 20. A rotary shaft of the generator 22 is
connected to an output shaft of an engine 24, which is an internal
combustion engine for driving the generator. The generator 22 is a
permanent electromagnet type generator but may be of any suitable
type.
[0020] The second inverter 20 is also electrically connected to an
auxiliary motor 26, which drives auxiliaries such as an air
compressor 27 for an air brake and a power steering pump 28. As is
the case with the first inverter 14, the second inverter 20
supplies stable power to the battery 12 or the traction motor 10 by
adjusting a voltage and a current generated by the generator 22, or
supplies stable power to the auxiliary motor 26 by adjusting the
voltage and the current from the battery 12. The inverter 20 also
has a function of adjusting the voltage and the current from the
battery 12 and supplying them to the generator 22.
[0021] A relay fuse 30 is mounted between the battery 12 and the
first and second inverters 14, 20. The relay fuse 30 is
electrically connected to the inverter 14, and allows a current to
flow from the battery 12 to the traction motor 10 or prevents an
excessive current from flowing from the battery 12 to the traction
motor 10 in accordance with information from the inverter 14. The
relay fuse 30 also has a function of preventing the generator 22 or
traction motor 10 during regenerative braking (the engine
regeneration) from excessively charging the battery 12.
[0022] As shown in FIG. 1, the battery 12 and the first and second
inverters 14, 20 are electrically connected to an electronic
control unit (ECU) 40 so that the battery 12 and the first and
second inverters 14, 20 can communicate with the ECU 40. The first
inverter 14 and the second inverter 20 are electrically connected
to the traction motor 10 and the generator 22, respectively, so
that they can communicate with one another. The ECU 40 is connected
to a battery controller 46, which monitors a charging level (SOC:
state of charging), etc. of the battery 12, and an engine
controller 48, which controls the operation of the engine 24. The
engine controller 48 also has a function of sensing an engine
revolution speed Ne and sensing an engine temperature Te from a
coolant temperature of the engine 24 by a suitable temperature
sensing device (not shown).
[0023] In the hybrid vehicle that is constructed in the
above-mentioned manner, a required motor torque signal
corresponding to a control input of an accelerator pedal (not
shown) is supplied to the first inverter 14 while the vehicle is
running. In accordance with the signal, the first inverter 14
adjusts the voltage and the current from the battery 12, and
therefore, the traction motor 10 generates a desired motor torque.
If the battery controller 46 senses a drop in the SOC of the
battery 12, the engine controller 48 starts the engine 24 to
operate the generator 22, which generates power to charge the
battery 12 in accordance with the SOC. If the SOC of the battery 12
is low, the power equivalent to a power consumption of the traction
motor 10 is directly fed from the generator 22 to the traction
motor 10 so that the surplus power from the generator 22 can be
charged in the battery 12.
[0024] If, for example, a brake pedal (not shown) is operated to
brake the vehicle and the control input of the accelerator pedal is
zero, the traction motor 10 performs regenerative braking and
generates power to charge the battery 12. While the vehicle is
running, the power from the battery 12 appropriately runs the
auxiliary motor 26 in order to drive the auxiliaries such as the
compressor 27 and the power steering pump 28.
[0025] If the SOC of the battery 12 is decreased, the engine 24 is
started to cause the generator 22 to generate power as stated
above. If, however, the engine 24 is static for a long period of
time, the engine 24 becomes cold. Thus, the engine 24 must be
warmed up in order to acquire a stable output. There will now be
described the operation of the warm-up control device in the hybrid
electric vehicle, i.e., the warm-up control for the engine 24.
[0026] FIG. 2 is a flow chart showing a control routine of the
warm-up control according to the present invention, which is
executed by the ECU 40. A description will hereunder be given with
reference to the flow chart. When a drop in the SOC of the battery
12 is sensed in accordance with the information from the battery
controller 46, the engine controller 48 starts the engine 24.
First, it is determined in a step S10 whether the engine 24 has
been started or not in accordance with the information from the
engine controller 48. If Yes, the process goes to a step S12.
[0027] In the step S12, it is determined whether the engine
temperature Te is higher than a preset temperature (Tw) (Te>Tw)
or not in accordance with the engine temperature information Te
from the engine controller 48. If Yes, the process goes out of the
routine. If No, the process goes to a step S14.
[0028] In the step S14, it is determined whether the engine
temperature Te is higher than a first preset first temperature Twa
(Twa<Tw) (Te<Twa) or not. If Yes, i.e., the engine
temperature Te is determined as being higher than the first preset
temperature Twa and being not greater than the set temperature Tw,
the process goes to a step S16.
[0029] In the step S16, a small power generation load is applied.
More specifically, a load equivalent to a small power generation
(the first set load) is applied to the engine 24 to thereby warm up
the engine 24. In more detail, the small power generation load (the
first set load) is applied to the generator 22 in order to cause
the generator 22 to generate a small amount of power. On the other
hand, the engine controller 48 issues an engine output command to
the engine 24 in order to maintain the engine revolution speed Ne
at a predetermine low revolution speed Ne1 (e.g., 500 rpm) against
the small power generation load (the first set load) of the
generator 22. More specifically, fuel injection information is
supplied to a fuel injection valve (not shown) of the engine 24 in
order to make it possible to maintain the engine revolution speed
Ne at the predetermined low revolution speed Ne1 against the small
power generation load (the first set load) of the generator 22.
[0030] Therefore, the engine 24 injects a larger quantity of fuel
from the fuel injection valve than fuel required for operating the
unloaded generator 22 to thereby achieve an engine output in
opposition to the small power generation load (the first set load)
of the generator 22 although the engine revolution speed Ne is as
low as the predetermined low revolution speed Ne1. This generates a
large amount of combustion heat, and facilitates the warm-up of the
engine 24. More specifically, loading the generator 22 makes it
possible to warm up the engine 24 more quickly within a shorter
period than in the case where the unloaded generator 22 is
operated. In this case, there is no necessity of raising the engine
revolution speed Ne.
[0031] If the engine revolution speed Ne is maintained at the
predetermined low revolution speed Ne1 (e.g., 500 rpm) during the
warm-up of the engine 24, the engine 24 can be kept quiet with
reduced noise and vibration. Moreover, it is possible to prevent
each sliding part of the engine 24 from being damaged by the
increase in the engine revolution speed in the case where the
engine 24 is cold and is not completely smooth. This extends the
life of the engine 24.
[0032] More specifically, the warm-up control device of the present
invention can warm up the engine 24 while extending the life of the
engine 24. In a next step S18, it is determined whether or not the
engine temperature Te is higher than a second predetermined
temperature Twe (Twe>Tw) preset as a warm-up completion
temperature (Te>Twe). If No, the warm-up of the engine 24 is
continued in the step S16. If Yes, the process goes to a step S24
where it is determined that the warm-up is completed and the
application of the power generation load is finished.
[0033] If No, i.e., it is determined in the step S14 that the
engine temperature Te is not greater than the first predetermined
temperature and the engine 24 is quite cold, the process goes to a
step S20. In the step S20, a medium power generation load (the
second set load) is applied. More specifically, a load equivalent
to a medium power generation (the second set load) is applied to
the engine 24 to thereby warm up the engine 24.
[0034] In more detail, as is the case with the application of the
small power generation load, the medium power generation load (the
second set load) higher than the small power generation load (the
first set load) is applied to the generator 22 to cause the
generator 22 to generate medium power. On the other hand, the
engine controller 48 issues an engine output command to the engine
24 in order to maintain the engine revolution speed Ne at a
predetermine low revolution speed Ne1 (e.g., 500 rpm) against the
medium power generation load (the second set load). More
specifically, fuel injection information is supplied to a fuel
injection valve (not shown) of the engine 24 in order to make it
possible to maintain the engine revolution speed Ne at the
predetermined low revolution speed Ne1 against the medium power
generation load (the second set load) of the generator 22.
[0035] FIG. 3 shows the relationship between a generator revolution
speed Ng (=Ne) and a generation torque Tg of the generator 22 or a
load. If the load (the second set load) equivalent to the medium
power generation is applied to the engine 24, the medium power
generation load (the second set load Tg2: white circle) higher than
the small power generation load (the first set load Tg1: black
circle) is applied to the generator 22. The engine 24 is controlled
so as to maintain the generator revolution speed Ng (=Ne) at the
predetermined low revolution speed Ng1 (=Ne1: 500 rpm).
[0036] Therefore, the engine 24 injects a larger quantity of fuel
from the fuel injection valve than fuel required for operating the
unloaded generator 22 to thereby achieve an engine output in
opposition to the medium power generation load (the second set
load) of the generator 22 although the engine revolution speed Ne
is as low as the predetermined low revolution speed Ne1. This
generates a large amount of combustion heat, and facilitates the
warm-up of the engine 24.
[0037] More specifically, the medium power generation (the second
set load) higher than the small power generation (the first set
load) is applied to the generator 22, and the engine 24 is
controlled so as to maintain the engine revolution speed Ne at the
predetermined low revolution speed Ne1. This makes it possible to
warm up the engine 24 more quickly within a shorter period than in
the case where the generator 22 with the small power generation
load (the first set load) is operated. At the same time, it is
possible to maintain the quietness of the engine 24 and extend the
life of the engine 24.
[0038] As is the case with the step S18, it is determined in a step
S22 whether the engine temperature Te is higher than the second
predetermined temperature Twe (Te>Twe) or not. If No, the
warm-up of the engine 24 is continued in the step S20. If Yes, the
process goes to the step S24 where it is determined that the
warm-up is completed. Accordingly, the application of the power
generation load is finished.
[0039] If the warm-up of the engine 24 is completed, the engine
revolution speed Ne is raised from the predetermined revolution
speed Ne1 as is normal to cause the generator 22 to start
generating the power.
[0040] According to the above embodiment, the load of the generator
22 can be divided into the following two stages: the small power
generation load equivalent to the small power generation the first
set load) and the medium power generation load equivalent to the
medium power generation (the second set load). The present
invention, however, should not be restricted to this. For example,
the load of the generator 22 may be changed in a plurality of
stages according to the engine temperature Te, and accordingly, the
engine 24 may be controlled so as to maintain the engine revolution
speed Ne at the predetermined low revolution speed Ne1.
[0041] According to the above embodiment, whether the engine is
cold or not is determined according to the engine temperature. The
present invention, however, should not be restricted to this. For
example, whether the engine is cold or not may be determined
according to a period from the stop to the start of the engine.
[0042] It should be understood, however, that there is no intention
to limit the invention to the specific forms disclosed, but on the
contrary, the invention is to cover all modifications, alternate
constructions and equivalents falling within the spirit and scope
of the invention as expressed in the appended claims.
* * * * *