U.S. patent application number 11/711438 was filed with the patent office on 2007-09-06 for exhaust purification system for hybrid vehicle.
This patent application is currently assigned to Nissan Motor Co., Ltd.. Invention is credited to Hiroshi Ishii.
Application Number | 20070204594 11/711438 |
Document ID | / |
Family ID | 38470290 |
Filed Date | 2007-09-06 |
United States Patent
Application |
20070204594 |
Kind Code |
A1 |
Ishii; Hiroshi |
September 6, 2007 |
Exhaust purification system for hybrid vehicle
Abstract
An exhaust purification system for a hybrid vehicle with an
internal combustion engine and an electric motor capable of being
driven by the engine includes a battery, an exhaust gas passage, an
exhaust purification device and at least one controller. The
battery is connected to the electric motor and selectively charged
with electric power generated by the electric motor. The exhaust
gas passage is connected to the internal combustion engine and the
exhaust purification device is disposed in the exhaust gas passage.
The at least one controller selectively performs regeneration
control of the exhaust purification device and controls the engine
and the electric motor to ensure that the battery does not become
overcharged.
Inventors: |
Ishii; Hiroshi; (Kanagawa,
JP) |
Correspondence
Address: |
RADER, FISHMAN & GRAUER PLLC
39533 WOODWARD AVENUE, SUITE 140
BLOOMFIELD HILLS
MI
48304-0610
US
|
Assignee: |
Nissan Motor Co., Ltd.
|
Family ID: |
38470290 |
Appl. No.: |
11/711438 |
Filed: |
February 27, 2007 |
Current U.S.
Class: |
60/274 ; 60/285;
60/299; 60/301 |
Current CPC
Class: |
B60L 2240/445 20130101;
B60W 2510/068 20130101; F01N 3/023 20130101; B60W 10/08 20130101;
F01N 3/0842 20130101; Y02T 10/6221 20130101; F01N 3/106 20130101;
F02D 2200/0804 20130101; Y02T 10/54 20130101; Y02A 50/20 20180101;
B60W 10/06 20130101; Y02T 10/6286 20130101; B60K 6/48 20130101;
B60W 2050/0026 20130101; F01N 3/0871 20130101; F01N 13/009
20140601; F02D 2041/026 20130101; Y02T 10/40 20130101; Y02T 10/62
20130101; F02D 41/029 20130101; B60Y 2300/476 20130101; F01N 3/035
20130101; B60K 6/543 20130101; B60L 7/10 20130101; B60W 2530/12
20130101; B60W 10/26 20130101; B60W 20/00 20130101; Y02A 50/2322
20180101; B60W 10/30 20130101; B60W 20/16 20160101; F02D 2200/0812
20130101 |
Class at
Publication: |
60/274 ; 60/285;
60/301; 60/299 |
International
Class: |
F01N 3/00 20060101
F01N003/00; F01N 3/10 20060101 F01N003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 2, 2006 |
JP |
2006-055628 |
Mar 3, 2006 |
JP |
2006-057522 |
Claims
1. An exhaust purification system for a hybrid vehicle comprising:
an internal combustion engine having an exhaust purification device
disposed in an exhaust gas passage of the engine to treat exhaust
gas components contained in exhaust gas from the engine; a motor
generator capable of generating electric power by being driven by
the engine; a battery arranged and configured to be selectively
charged with electric power generated by the motor generator; and
at least one controller arranged and configured to selectively
perform a regeneration control of the exhaust purification device
under a predetermined regeneration condition, in which deposits
accumulated in the exhaust purification device are burned and
removed by increasing exhaust gas temperature through an increase
in power output of the engine, and an excess power output caused by
the increase in power output of the engine is used to generate the
electric power by the motor generator, and wherein the at least one
controller is further arranged and configured to control the engine
and the motor generator so that the battery is prevented from
overcharging by the electric power associated with the regeneration
control of the exhaust purification device.
2. The exhaust purification system according to claim 1, wherein a
state of charge of the battery is reduced by selectively increasing
a power output of the motor generator before the regeneration
control.
3. The exhaust purification system according to claim 2, wherein a
target value of the state of charge of the battery is determined
corresponding to an accumulated level of the deposits in the
exhaust purification device.
4. The exhaust purification system according to claim 3, wherein
the target value of the state of charge of the battery becomes
smaller as the accumulated level of the deposits becomes
larger.
5. The exhaust purification system according to claim 2, wherein a
determination as to timing for increasing the power output of the
motor generator before the regeneration control is made in
accordance with an accumulated level of the deposits.
6. The exhaust purification system according to claim 2, further
including a compensation selectively adjusting a distribution of
the power output of the engine with respect to a requested total
power output of the vehicle.
7. The exhaust purification system according to claim 6, wherein
the requested total power output where the engine starts the power
output of the internal combustion engine is set to increase with
the compensation.
8. The exhaust purification system according to claim 6, wherein an
upper limit value that is set for the power output of the engine is
set to reduce with the compensation.
9. The exhaust purification system according to claim 6, wherein
the distribution of the power output of the engine with respect to
at least one of the requested total power output and the power
output of the motor generator is set to reduce with the
compensation.
10. The exhaust purification system according to claim 6, wherein a
compensation amount of the compensation is varied corresponding to
a deviation amount between an actual value and a target value of
the state of charge of the battery.
11. The exhaust purification system according to claim 10, wherein
the compensation selectively performs when the actual value of the
state of charge is larger than the target value of the state of
charge, but not to perform when the actual value is smaller than
the target value.
12. The exhaust purification system according to claim 1, wherein a
fuel injection timing of the engine is retarded in the regeneration
control of the exhaust purification device.
13. The exhaust purification system according to claim 12, wherein
at least one of an amount of the increase in power output of the
engine and an amount of the electric power generated by the motor
generator associated with the increase in power output of the
engine is determined so that a retard amount of the fuel injection
timing is prevented from falling within a range of retard amount
that causes exhaust gas aggravation or oil dilution.
14. The exhaust purification system according to claim 12, wherein
when the state of charge of the battery is lower than a first
predetermined value, the electric power generation by the increase
in power output of the engine is performed without retarding the
fuel injection timing, and when the state of charge of the battery
is higher than the first predetermined value, the fuel injection
timing is retarded and the electric power generation by the
increase in power output of the internal combustion engine is
performed.
15. The exhaust purification system according to claim 14, wherein
the power output of the engine during the regeneration control is
set at a fixed value regardless of a requested total power
output.
16. The exhaust purification system according to claim 14, wherein
at least one of an amount of the increase in power output of the
engine and an amount of the electric power generated by the motor
generator associated with the increase in power output of the
engine in the case where the state of charge of the battery is
larger than the first predetermined value is smaller than that in
the case where the state of charge is lower than the first
predetermined value.
17. The exhaust purification system according to claim 12, wherein
a current control is performed so that an electric power generation
efficiency of the motor generator is reduced when the motor
generator generate the electric power.
18. The exhaust purification system according to claim 14, wherein
a current control is performed so that an electric power generation
efficiency of the motor generator is reduced when the state of
charge of the battery is greater than a second predetermined value
that is higher than the first predetermined value.
19. The exhaust purification system according to claim 17, wherein
the current control is performed corresponding to an amount of the
electric power generated by the motor generator at which the power
output of the engine is larger than the requested total power
output.
20. The exhaust purification system according to claim 14, wherein,
when the state of the charge of the battery is greater than a
second predetermined value that is greater than the first
predetermined value, the hybrid vehicle is driven only by the power
output of the motor generator and the engine is rotated by the
motor generator to supply air to the exhaust purification
device.
21. The exhaust purification system according to claim 20, wherein
the engine is rotated by the motor generator at a rotational speed
where an amount of the air is capable of elevating the temperature
of the exhaust purification device through combustion in the
exhaust purification device.
22. The exhaust purification system according to claim 20, wherein,
under a condition where the exhaust purification device is cooled
down by the air supplied to the exhaust purification device when
the hybrid vehicle is driven only by the power output of the motor
generator, the rotation of the engine driven by the motor generator
is stopped so that the air supply to the exhaust purification
device is stopped.
23. The exhaust purification system according to claim 20, wherein,
under a condition where the exhaust purification device is cooled
down by the air supplied to the exhaust purification device when
the hybrid vehicle is driven by the power output of the motor
generator, a throttle valve of the engine is fully closed so that
the air supply to the exhaust purification device is stopped.
24. The exhaust purification system according to. Claim 20,
wherein, under a condition where the exhaust purification device is
cooled down by the air supplied to the exhaust purification device
when the hybrid vehicle is driven by the power output of the motor
generator, an EGR valve of the engine is fully opened so that the
air supply to the exhaust purification device is reduced.
25. The exhaust purification system according to claim 14, wherein
in the event that the state of charge of the battery is larger than
a second predetermined value that is larger than the first
predetermined value, when the exhaust purification device is
inactive, a current control is performed so that an electric power
generation efficiency of the motor generator is reduced, and when
the exhaust purification device is active, the hybrid vehicle is
driven by the power output of the motor generator and the engine is
rotated by the motor generator, providing an air supply to the
exhaust purification device.
26. An exhaust purification system for a hybrid comprising: an
internal combustion engine; first means for treating exhaust gas
components contained in exhaust gas from the engine; second means
for generating electric power by being driven by the engine; a
battery being selectively charged with electric power generated by
the second means; and third means for performing a regeneration of
the first means under a predetermined regeneration condition, in
which deposits accumulated in the first means are removed by
increasing exhaust gas temperature through an increase in power
output of the internal combustion engine, and an excess power
output caused by the increase in power output of the internal
combustion engine is used to generate electric power by the second
means, and wherein the internal combustion engine and the second
means is controlled so that the battery is prevented from
overcharging by the electric power associated with the regeneration
of the first means.
27. A method of controlling an exhaust purification system for a
hybrid vehicle including an engine and an electric motor capable of
being driven by the engine, a battery being selectively charged
with electric power generated by the electric motor; an exhaust
purification device provided in an exhaust passageway of the
engine, comprising: performing a regeneration of an exhaust
purification device under a predetermined regeneration condition in
which deposits accumulated in the exhaust purification device is
removed by increasing exhaust gas temperature through an increase
in power output of an engine; absorbing an excess power output
associated with the increase in power output of the engine by an
electric motor; and controlling the engine and the electric motor
so that a battery is prevented from overcharging by the electric
power caused by the regeneration of the exhaust purification
device.
28. The method as recited in claim 27, wherein a power output of
the electric motor is increased before performing the regeneration
such that a state of charge of the battery is reduced.
29. The method as recited in claim 27, wherein a fuel injection
timing of the engine is retarded during the regeneration of the
exhaust purification device.
Description
CROSS-REFERENCES TO RELATED APPLICATION
[0001] This application claims priority from Japanese Patent
Application Serial Nos. tokugan2006-055628 filed Mar. 2, 2006, and
tokugan2006-057522 filed Mar. 3, 2006, the entire contents of which
are incorporated herein by reference.
TECHNICAL FIELD
[0002] An exhaust purification system is disclosed related to
hybrid vehicles including, as vehicle drive sources, an internal
combustion engine and an electric motor serving as a power
generator concurrently. More specifically, the disclosed system
relates to regeneration techniques for exhaust purification devices
such as particulate matter (PM) collecting filters and NOx absorber
catalysts for use with an internal combustion engine.
BACKGROUND
[0003] Japanese Patent Application Laid-Open No. 2004-278465
(Patent Document 1, hereafter) discloses a hybrid vehicle. In the
hybrid vehicle deposits (e.g., sulfur) accumulated in an exhaust
purification device, such as one utilizing a NOx absorber catalyst,
provided in an exhaust passageway of an internal combustion engine
is removed by combustion, thereby to implement regeneration (poison
removal) of the exhaust purification device. During regeneration
power output of the engine is increased, the engine undertaking a
high load power generation operation. The exhaust temperature is
increased by operating the engine with a high load. By raising
exhaust temperature, the engine power generation quickly raises the
temperature of the exhaust purification device to a point necessary
for regeneration. At the same time a separate electric motor is
activated using at least some of the additional power output of the
engine. In such an operation, the amount of power generated (or
"power generation amount", herein below) is stored into a battery,
so that surplus energy is usable later on, thereby to restrain fuel
consumption from being aggravated by the regeneration.
[0004] However, the technique described in Patent Document 1 has
problems. For example, when the amount of charge (or "charge
amount", herein below) in the battery is increased to an
overcharged state, the battery may undesirably deteriorate. As
such, depending on the case, the high load power generation
operation cannot be continued further from that state. In turn,
temperature elevation cannot be maintained. Thus, regeneration
could be hindered.
[0005] In view of these circumstances, it is desirable to enable a
high load power generation operation without causing deterioration
of a battery affected by the operation, thereby improving
regeneration efficiency.
SUMMARY
[0006] An exhaust purification system for a hybrid vehicle with an
internal combustion engine and an electric motor capable of being
driven by the engine includes a battery, an exhaust gas passage, an
exhaust purification device and at least one controller. The
battery is connected to the electric motor and selectively charged
with electric power generated by the electric motor. The exhaust
gas passage is connected to the internal combustion engine and the
exhaust purification device is disposed in the exhaust gas passage.
The at least one controller selectively performs regeneration
control of the exhaust purification device and controls the engine
and the electric motor to ensure that the battery does not become
overcharged. This enables the regeneration control to be
implemented without causing deterioration of the battery due to
overcharging. Consequently, the regeneration efficiency can be
improved.
BRIEF DESCRIPTION OF DRAWINGS
[0007] While the claims are not limited to the illustrated
embodiments, an appreciation of various aspects of the system is
best gained through a discussion of various examples thereof.
Referring now to the drawings, illustrative embodiments are shown
in detail. Although the drawings represent the embodiments, the
drawings are not necessarily to scale and certain features may be
exaggerated to better illustrate and explain an innovative aspect
of an embodiment. Further, the embodiments described herein are not
intended to be exhaustive or otherwise limiting or restricting to
the precise form and configuration shown in the drawings and
disclosed in the following detailed description. Exemplary
embodiments of the present invention are described in detail by
referring to the drawings as follows.
[0008] FIG. 1 is a system diagram of a hybrid vehicle, which shows
a first exemplary embodiment of the system;
[0009] FIG. 2 is a control block diagram of the hybrid vehicle of
the first embodiment;
[0010] FIG. 3 is a diagram showing a power output distribution
table in a normal mode (M=0);
[0011] FIG. 4 is a diagram showing an engine operation point
table;
[0012] FIG. 5 is a diagram showing a motor operation point
table;
[0013] FIG. 6 is a diagram showing a power output distribution
table in a mode (M=1) during DPF regeneration;
[0014] FIG. 7 is a diagram showing a power output distribution
table in a mode (M=2) before DPF regeneration;
[0015] FIG. 8 is a diagram showing an example of a PM deposition
amount-SOC target value table;
[0016] FIG. 9 is a diagram showing the relation between a deviation
amount from a target value of a charge amount and a power output
boundary value;
[0017] FIG. 10 is a diagram showing a power output distribution
table in a DPF regeneration initiation mode (M=3);
[0018] FIG. 11 is a flow chart showing a control flow;
[0019] FIG. 12 is a timing chart showing a control flow;
[0020] FIG. 13 is a diagram showing another example of the PM
deposition amount-SOC get value table;
[0021] FIG. 14 is a diagram showing another example of the PM
deposition amount-SOC get value table;
[0022] FIG. 15 is a system diagram of a series hybrid vehicle;
[0023] FIG. 16 is a diagram showing a motor operation point table
in the series hybrid vehicle;
[0024] FIG. 17 is a diagram showing a sulfur deposition amount-SOC
target value table;
[0025] FIG. 18 is a control block diagram of a hybrid vehicle
according to another exemplary embodiment of the system;
[0026] FIG. 19 is a diagram showing a power output distribution
table in a normal mode (M=4);
[0027] FIG. 20 is a diagram showing an engine operation point
table;
[0028] FIG. 21 is a diagram showing a motor operation point
table;
[0029] FIG. 22 is a diagram showing a power output distribution
table in a power generation amount increase mode (M=5);
[0030] FIG. 23 is a diagram showing a power output distribution
table in a power generation amount restriction mode (M=6, 7);
[0031] FIG. 24 is a diagram showing an engine operation point table
in the power generation amount restriction mode (M=6, 7);
[0032] FIG. 25 is a characteristic diagram of an mount of
retardation of fuel injection timing in the power generation amount
restriction mode (M=6, 7);
[0033] FIG. 26 is a diagram showing a current compensation
characteristic in a current compensation mode (M=7);
[0034] FIG. 27 is a diagram showing the relation between a DPF
temperature and an engine speed in a motor driven travel mode
(M=8);
[0035] FIG. 28 is a flow chart showing a control flow in the
exemplary embodiment of FIG. 18;
[0036] FIG. 29 is a timing chart (1) showing the control flow in
the exemplary embodiment of FIG. 18; and
[0037] FIG. 30 is a timing chart (2) showing the control flow in
the exemplary embodiment of FIG. 18.
DETAILED DESCRIPTION
[0038] FIG. 1 is a system diagram of a hybrid vehicle, which shows
a first exemplary embodiment.
[0039] The hybrid vehicle includes, as vehicle drive sources, an
internal combustion engine I (or, simply "engine," here below) and
an electric motor 2 (alternately called "motor generator") 2
concurrently serving as a power generator. The motor 2 is
electrically connected to a battery 4 through an inverter 3.
[0040] Output shafts of the engine 1 and the motor 2, respectively,
are coupled to an input shaft of a final reduction gear device 7
through transmissions (belt continuous variable transmissions 5e
and 5m (each of which herein below will be referred to as "CVT")
and clutches 6e and 6m. Driving wheels are fitted onto output
shafts 8 (axle) of the final reduction gear device 7.
[0041] The engine 1 is, for example, a diesel engine, and is
capable of generating an arbitrary torque by controlling the amount
of fuel injection or the like.
[0042] The motor 2 can generate an arbitrary torque by consuming
the power of the battery 4.
[0043] The engine 1 and the motor 2 are each independently or both
cooperatively capable of driving the vehicle through the clutches
6e and 6m, respectively.
[0044] During deceleration of the vehicle, engine braking by the
engine 1 can be used. Moreover, regenerative braking is possible
whereby the motor 2 functions as a power generator to recapture at
least a portion of the kinetic energy that would otherwise be lost
to heat when braking and making use of that power by charging the
battery 4 through the inverter 3. In addition, during driving by
the engine 1, the motor 2 is driven through the clutch 6m and the
transmission 5m. Thus, the vehicle and the motor 2 are driven by
the engine 1, permitting the generation of power within motor 2
that is also chargeable to the battery 4 through the inverter
3.
[0045] As exemplary exhaust purification devices, an oxidation
catalyst 9, NOx absorber catalyst 10, and diesel particulate filter
(DPF) 11 are provided in an exhaust passageway 12 of the diesel
engine 1.
[0046] The oxidation catalyst 9 performs oxidation treatment of
exhaust and evaporative pollutant of hydrogen and carbon atoms (HC)
and Carbon Monoxide (CO) resulting from unburned fuel contained in
the exhaust gas.
[0047] The NOx absorber catalyst 10 absorbs oxides of nitrogen
(NOx) contained in the exhaust gas, and is capable of performing
absorption purification of NOx in a rich atmosphere.
[0048] The DPF 11 collects a particulate matter (PM) contained in
the exhaust gas, and contains a catalyst that promotes combustion
of PM during regeneration.
[0049] The DPF 11 is subject to plugging through the collection of
increasing deposits of PM, thereby introducing deterioration of
operability due to an increased exhaust resistance. When the
accumulated level or amount of PM deposits (or, "PM deposit
amount," herein below) is larger than a predetermined value,
regeneration is desired. Regeneration timing is the event timing
for addressing the PM deposit amount. When regeneration takes
place, a temperature rise of the DPF 11 is carried out resulting in
combustion of the PM deposit amounts. Thereby, combustion removal
of the PM deposits on the DPF 11 takes place, reducing the PM
deposit amount, and the DPF 11 is regenerated.
[0050] When used for a long time, the NOx absorber catalyst 10 is
poisoned by sulfur (S), thereby being deteriorated in NOx
adsorption efficiency. For this reason, the amount or level of
amount of sulfur deposits (amount of sulfur poisoning) is
estimated. When the estimated amount of sulfur becomes larger than
a predetermined value, regeneration is necessary as a poison
removal process. As with DPF 11, when regeneration takes place, a
temperature rise of the NOx absorber catalyst is carried out,
resulting in combustion of the sulfur deposits. Thereby, combustion
removal of the sulfur deposits on the NOx absorber catalyst takes
place, reducing the amount of sulfur, and the NOx absorber catalyst
is regenerated (poison-removed).
[0051] In the event of regeneration of an exhaust purification
device (DPF 11, NOx absorber catalyst 10), the power output of the
engine 1 is increased, and the motor 2 is driven by using an excess
power output with respect to a requested power output, thereby to
generate power. As a consequence, the high load power generation
operation of the diesel engine 1 is carried out to cause
temperature rise of the exhaust temperature, and the amount of
generated power is charged to the battery 4.
[0052] A controller 100 is connected to the engine 1 and the motor
2. While a single controller 100 is shown, one or more controllers
working together is also possible. The controller 100 performs the
above-described operations of control, such as engine control,
motor control, and control for cooperative control between the
engine and motor, such as distribution of the engine power output
and motor power output with respect to a requested total power
output.
[0053] In addition, in the present exemplary embodiment, the
internal combustion engine 1 and the electric motor 2 undergo
cooperative control before the regeneration control. The
cooperative control is so performed such that the charge amount in
the battery 4 is reduced corresponding to the amount of deposits
(PM, sulfur) in the exhaust purification devices. As a result, the
battery is prevented from being overcharged in the event of the
regeneration control. An example of cooperative control may be
illustrated using the regeneration of the DPF.
[0054] FIG. 2 is a control block diagram of the hybrid vehicle. As
illustrated in FIG. 2, the vehicle includes an operation state
detecting mechanism B1 that detects the operation state of the
vehicle; an operation point determining mechanism B2 that
determines respective operation points of the engine and motor in
accordance with the detection results; an engine control mechanism
B3, which controls the engine 1 in accordance with a determined
engine operation point; and a motor control mechanism B4 that
controls the motor in accordance with a determined motor operation
point.
[0055] More specifically, the operation point determining mechanism
B2 is configured to alter an operation point in accordance with an
operation mode specified by an operation mode altering mechanism B5
in the relation with the regeneration control of the DPF 11. The
operation mode altering mechanism B5 contains information input
from a DPF deposit amount estimating mechanism B6, a DPF
temperature detecting mechanism B7, and a charge amount detecting
mechanism B8.
[0056] The DPF deposit amount estimating mechanism B6 uses, for
example, a differential pressure sensor that detects a differential
pressure between an upstream exhaust pressure in the DPF 11 and a
downstream exhaust pressure therein, thereby to estimate a PM
deposit amount, C, from the detected differential pressure and an
engine operation state (volume of exhaust flow or engine speed and
load defining the volume of exhaust flow). Alternatively, the PM
deposit amount, C, can be estimated using mechanism B6 in such a
manner that the amounts of collected PM per unit time are estimated
from the engine operation state and the results are integrated.
[0057] The DPF temperature detecting mechanism B7 detects a DPF
temperature T by using a sensor that detects, for example, the
temperature of a DPF carrier or exhaust temperatures of a
downstream side and/or upstream side of the DPF 11.
[0058] The charge amount detecting mechanism B8 detects a battery
charge amount, SOC, through the integration of charge and discharge
currents by using a current sensor that detects charge and
discharge currents of the battery. Normally, the charge amount,
SOC, is obtained as a ratio (%) to the full amount of charge.
[0059] Operation modes to be specified by the operation mode
altering mechanism B5 correspondingly to, for example, the state of
the DPF 11 will now be described here below.
[0060] The operation modes are a normal mode (M=0), a DPF
regeneration mode (M=1) during DPF generation, a motor power output
increase mode (charge amount reduction mode; M=2) before DPF
generation, and an engine power output increase mode (power
generation amount increase mode; M=3) in a DPF generation
initiation event. The respective modes will be described here
below.
[0061] The normal mode (M=0) is a normal operation mode. In this
mode, a requested total power output Pt0 requested for the vehicle
is calculated in accordance with operation state information
received from the operation state detecting mechanism B1. In
addition, an engine power output Pe0 and a motor power output Pm0
are determined from the requested total power output Pt0 by using a
hybrid power output (engine/motor power output) distribution table
of FIG. 3, which shows a distribution of hybrid power output with
respect to the total power output. Then, the determined power
outputs Pe0 and Pm0 are supplied for commands to the engine control
mechanism B3 and the motor control mechanism B4. FIG. 3 also
illustrates a total power output lower limit value, Pmc, which is
discussed in greater below with respect to FIG. 7.
[0062] In the engine control mechanism B3, an operation point is
determined by using an engine operation point table as illustrated
in FIG. 4 in accordance with the determined motor power output Pm0.
The operation point table is created by setting combinations of
torques (Te0, Te1, . . . ) and rotational speeds (Ne0, Ne1, . . .
), which optimize fuel consumption, with respect to the respective
engine power output values (Pe0, Pe1, . . . ).
[0063] In the motor control mechanism B4, an operation point is
determined by using a motor operation point table as illustrated in
FIG. 5 in accordance with the determined engine power output Pe0.
The operation point table is created by setting combinations of
torques (Tm0, Tm1, . . . ) and rotational speeds (Nm0, Nm1, . . .
), which optimize fuel consumption, with respect to the respective
motor power output values (Pm0, Pm1, . . . ).
[0064] The DPF regeneration mode (M=1) is an operation mode during
DPF regeneration, and is used to increase the amount of power
generated by slightly increasing the engine power output so as not
to reduce the exhaust temperature. As such, an engine power output
Pe0 and a motor power output Pm0 are determined from a requested
total power output Pt0 by using a hybrid power output distribution
table as illustrated in FIG. 6. Then the determined power outputs
Pe0 and Pm0 are supplied for commands to the engine control
mechanism B3 and the motor control mechanism B4. In the hybrid
power output distribution table of FIG. 6, particularly the engine
power output Pe0 is maintained at a value greater than or equal to
a specified power output P0, whereby, in a low power output zone,
an excess amount (Pe0-Pt0) of the engine power output Pe0 with
respect to the requested total power output Pt0 is set to be an
amount of power generated in the motor.
[0065] The motor power output increase mode (M=2) is an operation
mode before DPF generation (preparatory stage), in which a charge
amount SOC is progressively reduced by increasing the motor power
output ratio. As such, an engine power output Pe0 and a motor power
output Pm0 are determined from a requested total power output Pt0
by using a hybrid power output distribution table of FIG. 7. Then
the determined power outputs Pe0 and Pm0 are supplied for commands
to the engine control mechanism B3 and the motor control mechanism
B4. In the hybrid power output distribution table of FIG. 7, a
requested total power output lower limit value Pmc for starting the
engine power output is increased, and concurrently, an upper limit
value Pec of the engine power output is reduced, thereby to reduce
the engine power output ratio to the requested total power
output.
[0066] Further, in the motor power output increase mode (M=2), by
referencing table of FIG. 8, a target value Et of the charge amount
SOC is set corresponding to the PM deposit amount C. In the event
that the PM deposit amount C is a predetermined value Cp or more,
the target value Et of the charge amount SOC is reduced to be
smaller as the PM deposit amount C becomes larger. In addition,
where the PM deposit amount C is close to a predetermined value for
regeneration timing determination (regeneration-request occurring
deposit amount) Ce, it is set as Et=Es (fixed value).
[0067] Then, as the target value Et of the charge amount SOC
becomes smaller, the engine power output ratio to the requested
total power output is reduced to be smaller, and the motor power
output ratio is increased.
[0068] More specifically, as shown in FIG. 9, as a deviation amount
(.DELTA.E=SOC-Et), i.e., the amount of deviation of an actual value
SOC of the charge amount with respect to the target value Et, is
larger, the requested total power output lower limit value Pmc for
raising the engine power output in the hybrid power output
distribution table of FIG. 7 is compensated to be increased, and
the upper limit value Pec of the engine power output in the same
table is compensated to be reduced. That is, in the motor power
output increase mode (M=2), with respect to the normal mode (M=0),
the requested total power output lower limit value Pmc for raising
the engine power output is compensated to be increased, and the
upper limit value Pec of the engine power output is decrementally
compensated to be reduced. However, instead of the decremental
compensation of the upper limit value Pec of the engine power
output, the ratio of the engine power output Pe to either the
requested total power output Pt0 or motor power output Pm can be
reduced. The compensation in this case is carried out when the
actual value SOC of the charge amount is larger than the target
value Et (i.e., when E>0). The amount of compensation is set to
0 when the actual value SOC of the charge amount is smaller than
the target value Et (i.e., when .DELTA.E<0). That is, the table
of FIG. 3 is set with Pmc and Pec set as defaults or initial
values.
[0069] The engine power output increase mode (M=3) is an operation
mode for use in the DPF regeneration initiation event (when a DPF
regeneration request is present and the DPF temperature is low). In
this mode, the engine power output is largely increased to thereby
largely increase the amount of power generated. The mode is thus
set for the reason that the exhaust temperature is raised by the
high load operation of the engine to thereby promote the elevation
of the DPF temperature. As such, an engine power output Pe0 and a
motor power output Pm0 are determined from a requested total power
output Pt0 by using a hybrid power output distribution table as
illustrated in FIG. 10. Then the determined power outputs Pe0 and
Pm0 are supplied for commands to the engine control mechanism B3
and the motor control mechanism B4. In the hybrid power output
distribution table of FIG. 10, the engine power output Pe0 is set
to a large fixed value in the entire zone. Thereby, in a
low/intermediate power output zone, an excess amount (Pe0-Pt0) of
the engine power output Pe0 with respect to the requested total
power output Pt0 is set to be an amount of power generated in the
motor.
[0070] A flow of control will now be described with reference to a
flow chart as illustrated in FIG. 11.
[0071] In step A1, a determination is made as to the presence or
absence of a DPF regeneration request. More specifically, the
process reads a PM deposit amount (estimated value) C in the DPF
11, which is calculated in a different routine. Then, the process
determines whether or not the read value is greater than or equal
to a predetermined value Ce for regeneration timing determination.
Alternatively, as shown in FIG. 11, C can simply be required to be
greater than Ce.
[0072] If a DPF regeneration request is absent (C<Ce) as a
result of the determination in step A1, the process proceeds to
step A2. In step A2, it is determined whether or not preparation
for DPF regeneration is necessary, that is, whether or not the
state is prior to regeneration control. More specifically, it is
determined whether or not the PM deposit amount (estimated value) C
is greater than or equal to the predetermined value Cp for
regeneration preparation timing determination. Cp is smaller than
Ce (Cp<Ce).
[0073] If the DF regeneration preparation is not necessary (if
C<Cp) as a result of the determination in step A2, the process
proceeds to step A3. In step A3, the mode is set to and maintained
in the normal mode (M=0).
[0074] Alternately, if the DPF regeneration preparation is
necessary (if C>Cp) as a result of the determination in step A2,
the process proceeds to step A6. In step A6, it is determined
whether or not the charge amount SOC in the battery 4, which is
calculated by the different routine, is greater than or equal to
the predetermined value Es. Alternatively, as shown in FIG. 11, SOC
can simply be required to be greater than Es. The predetermined
value Es corresponds to a target charge amount at DPF regeneration
timing (DPF-regeneration-request deposit amount Ce) (see FIG. 10);
that is, after the charge amount is reduced to the level of the
value, the value is sufficiently achievable for charging.
[0075] If SOC>Es as a result of the determination in step A6,
the process proceeds to step A7. In step A7, the mode is set to the
motor power output increase mode (M=2), which is the charge amount
reduction mode before regeneration. Thereby, the charge amount SOC
is reduced to Es.
[0076] Alternately, if SOC<Es as a result of the determination
in step A6, the process proceeds to step A9, in which the mode is
set to the engine power output increase mode (M=3), which is the
power generation amount increase mode. Thereby, conversely to the
above case, the charge amount is prevented from being over-reduced,
and the charge amount SOC is maintained at Es.
[0077] Thereafter, if a DPF regeneration request is present (i.e.,
if C>Ce) as a result of the determination in step A1, the
process proceeds to step A4, in which it is determined whether or
not the mode is the DPF regeneration mode (M=1). If the mode is not
the mode (M=1), the process proceeds to step A5, in which it is
determined whether or not the mode is the motor power output
increase mode (M=2).
[0078] If the mode is the motor power output increase mode (M=2) as
a result of the determination in step A5, the process proceeds to
step A6. If, in step A6, SOC>Es, the motor power output increase
mode (M=2), which is the charge amount reduction mode, is
maintained in step A7.
[0079] Alternately, if SOC<Es as a result of the determination
in step A6, the process proceeds to step A9. In step A9, the mode
is shifted to the engine power output increase mode (M=3), which is
the power generation amount increase mode in the regeneration
initiation event.
[0080] After the mode has been set to the mode (M=3), the mode
(M=2) is not detected in the determination in step A5, so that the
process proceeds from the step A5 to step A8. In step A8, a DPF
temperature T calculated by the different routine is read, and
unless the DPF temperature T is a predetermined value Th or more,
the process proceeds to step A9, in which the engine power output
increase mode (M=3), which is the power generation amount increase
mode in the regeneration initiation event is maintained. Thereby,
the high load power generation operation of the engine 1 is
performed, thereby to raise the exhaust temperature for DPF
regeneration.
[0081] Thereafter, if T (DPF temperature)>Th as a result of the
determination in step A8, the process proceeds from step A8 to step
A10, in which the mode is set to the DPF regeneration mode (M=1),
which is the mode during regeneration. The predetermined value Tb
represents a DPF-regeneration target temperature at which PM
deposited in the DPF 11 is combustible.
[0082] Then, the mode is determined in step A4 to be the DPF
regeneration mode (M=1) until termination of DPF regeneration.
Therefore, the process proceeds from step A4 to step A10, in which
the DPF regeneration mode (M=1) is maintained.
[0083] FIG. 12 illustrates a timing chart for flow control. In the
event that the PM deposit amount C (estimated value) in the DPF 11
exceeds the predetermined value Cp at time t0, the timing of the
event is determined to be pre-generation timing. In this case, the
mode is shifted from the normal mode (M=0) to the motor power
output increase mode (M=2), which is the charge amount reduction
mode before regeneration. Thereby, the motor power output is
increased to thereby reduce the charge amount SOC before
regeneration. In this event, the target charge amount Es is reduced
corresponding to the PM deposit amount C or is reduced to be
smaller as the PM deposit amount C is increased to be larger,
thereby to progressively reduce the charge amount SOC.
[0084] Thereafter, in the event that the PM deposit amount C in the
DPF 11 exceeds the predetermined value Ce at time t1, the timing of
the event is determined to be the regeneration timing. However,
during the period of time in which the battery charge amount SOC
reduces to the final target value Es, the motor power output
increase mode (M=2), which is the charge amount reduction mode, is
maintained.
[0085] Then, in the event that the charge amount SOC has reduced to
the final target value Et at time t2, the mode is shifted to the
engine power output increase mode (M=3), which is the power
generation amount increase mode in the regeneration initiation
event. Thereby, the engine power output is increased and the motor
2 is driven by an excess power output of the engine 1 to thereby
generate the power. Then, with the high load power generation
operation of the engine 1, the exhaust temperature is raised, and
the DPF temperature T is raised. While the amount of power
generated in this event is used to charge the battery 4, the amount
of charge stored in the battery 4 is preliminarily reduced, so that
the battery 4 is prevented from being overcharged. An upper limiter
for the charge amount SOC can be set higher than usual.
[0086] Subsequently, in the event that, at time t3, the DPF
temperature T has reached the target value Tb at which regeneration
is possible, the mode is shifted to the DPF regeneration mode
(M=1), in which operation at a power level not reducing the DPF
temperature is carried out.
[0087] As described above, according to the present embodiment,
control is carried out in the following manner. In the event of
regeneration of the DPF, the power output of the engine is
increased to thereby drive the motor, whereby the high load power
generation operation is carried out to increase the exhaust
temperature. Before the regeneration, the power output of the motor
is increased, thereby to reduce the amount of charge stored in the
battery. Thereby, in the event of regeneration, even more
sufficiently high load power generation operation can be
implemented. Consequently, the exhaust temperature can be quickly
increased, and the battery can be prevented from being deteriorated
due to overcharge.
[0088] Further, according to the exemplary embodiment, the amount
of charge in the battery is varied corresponding to the amount of
deposits of PM in the DPF. Consequently, the amount of charge in
the battery can be adjusted in preparation for a request for the
regeneration of the DPF.
[0089] Control is performed such that, when the PM deposit amount
in the DPF is the predetermined value or more, the charge amount is
reduced to be smaller as the deposit amount is larger. Thereby, the
charge amount is progressively reduced before the initiation of DPF
regeneration, consequently making it possible to implement a
long-term high load power generation operation in the regeneration
initiation event.
[0090] Further, according to the present exemplary embodiment, the
determination of whether or not a mode underway is anterior to
regeneration control is made in accordance with the estimate value
of the amount of deposits. Thereby, the time before the
regeneration can be quantitatively determined, so that the charge
amount reduction control can be performed at appropriate timing
before occurrence of a regeneration request.
[0091] Further, according to the present illustrated embodiment,
the reduction control for the charge amount SOC is carried out in
the following manner. In the power output distribution control for
the engine and the motor with respect to the requested total power
output, at least one of the following processes of control is
performed. They are the incremental compensation for the requested
total power output lower limit value Pmc for raising the engine
power output, decremental compensation for the upper limit value
Pec of the engine power output, and decremental compensation for
the engine power output ratio with respect to the requested total
power output. With the process of control, the cooperative control
is carried out to cause variations of the power output
distributions of the engine and the motor, thereby to direct the
power balance of the motor to the negative trend, whereby the
charge amount SOC can be securely reduced. 100
[0092] According to the present embodiment, the amount of the
compensation described above amount is varied corresponding to the
deviation amount (.DELTA.E=SOC-Et), i.e., the amount of deviation
of an actual value SOC of the charge amount with respect to the
target value Et set corresponding to the PM deposit amount.
Thereby, the power balance of the motor is further directed in the
negative trend as the deviation amount .DELTA.E is larger, thereby
to enable it to improve followability to the target value Et.
[0093] Further, according to the present embodiment, the
compensation described above is performed in the event that the
actual value SOC of the charge amount is larger than the target
value Et, but is not performed in the event that the actual value
SOC is smaller than the target value Et. As a consequence, even in
the case of SOC reduced to a level appropriate for
"temperature-rise power generation", SOC can be maintained to be
that reduced in an early stage when the influence thereof is
considered less on the operability. That is, SOC is not forcedly
increased, thereby to enable the operation to be performed as in an
even more appropriately selected pattern.
[0094] In the present embodiment described above, as shown in FIG.
8, the target value Et of the charge amount SOC corresponding to
the PM deposit amount C is set as a single value. As an alternative
case, however, the target value Et can be set as a target range
defined by an upper limit value and a lower limit value.
[0095] More specifically, for example, as shown in FIG. 13, the
target value can be set as a target range defined by a SOC upper
limit value and a SOC lower limit value. In this case, when the PM
deposit amount C is the predetermined value or more, the SOC upper
limit value is reduced to be smaller as the PM deposit amount C is
larger.
[0096] Still alternatively, the target value can be set as a target
range defined by a SOC upper limit value and a SOC lower limit
value, as shown in FIG. 14. After the PM deposit amount C has
reached a predetermined value C1 larger than the
regeneration-request occurring deposit amount Ce, the SOC upper
limit value is reduced to be smaller as the PM deposit amount is
larger. More specifically, depending on the case, there occurs an
instance in which the charge amount SOC naturally reduces.
Therefore, such an instance is awaited, and SOC is forcedly reduced
at the level larger than the predetermined value C1 in the event
that SOC does not reduce. In this case, the timing of the
regeneration initiation is set to an instance at which the DPF
regeneration request is present and SOC has reached the
regeneration initiation SOC.
[0097] In the event that the target value of the charge amount is
set as a target range such as described above, the amount of
compensation of the respective power output boundary value Pmc, Pec
of FIG. 9 is increased to be greater as the actual SOC, i.e., an
upper limit value (.DELTA.E=actual SOC-SOC), is greater than the
SOC upper limit value in the target range. That is, as the
followability of the actual SOC deviates more greatly with respect
to the SOC upper limit value, the power balance of the motor is
further directed in a negative trend, thereby to improve the SOC
followability.
[0098] While the embodiment has been described with reference to
the parallel hybrid vehicle (shown in FIG. 1), it is adaptable as
well to a series hybrid vehicle.
[0099] FIG. 15 is a system diagram of a series hybrid vehicle to
which the system is adaptable.
[0100] In the system, an output shaft of an engine 1 and an output
shaft of a motor 2 are coaxial and directly coupled together. The
single output shaft is coupled to an input shaft of a final
reduction gear device 7 through a transmission (belt continuous
variable transmission (CVT)) 5 and a clutch 6.
[0101] The illustrated embodiment is adaptable as well to the
hybrid vehicle of the type illustrated in FIG. 1. In this case,
however, the engine 1 and the motor 2 have the same rotational
speed. For this reason, by using the engine operation point table
of FIG. 4, the engine control mechanism B3 determines respective
engine operation points (rotational speeds Ne0 and Ne1, and torques
Te0 and Te1) from the requested engine power outputs Pe0 and Pe1.
However, the motor control mechanism B4 uses an operation point
table as illustrated in FIG. 16 in place of the motor operation
point table illustrated in FIG. 5. As already noted, the engine 1
and the motor 2 have the same rotational speed. Therefore, in the
event of the rotational speeds of Ne0 and Ne1, when the request
motor power outputs are Pm0 and Pm1, motor torques are determined
to be Tm0=Pm0/Ne0 and Tm1=Pm1/Ne1, respectively, as shown in FIG.
16.
[0102] Thus, the first embodiment has been described with reference
to the case where the exhaust purification device is the DPF, and
PM deposited therein is burned out under the predetermined
regeneration condition. However, the embodiment can be applied as
well to the case where the exhaust purification device is a NOx
absorber catalyst, and sulfur deposited therein is burned out under
a predetermined regeneration condition.
[0103] In this case, as shown in FIG. 17, the target value Et of
the charge amount SOC in the battery is set corresponding to the
amount of sulfur deposits (amount of sulfur poisoning) in the NOx
absorber catalyst.
[0104] The amount of sulfur deposits (amount of sulfur poisoning)
can be estimated in such a manner that the amounts of sulfur
poisoning per unit time are estimated from an operational state of
the engine and integrated. Alternatively, the amount of sulfur
poisoning can be simply estimated from an integrated travel
distance.
[0105] The exhaust purification system may be implemented using an
approach both similar to and in some ways different from the
approach discussed above. Once again referring to FIG. 1, the
engine 1 is, for example, a diesel engine, which is capable of
generating an arbitrary torque by controlling the fuel injection
quantity and the like. Further, the engine 1 is capable of raising
the exhaust temperature through retardation in fuel injection
timing (including post-injection in either the expansion stroke or
exhaust stroke).
[0106] However, when the elevation of the exhaust temperature is
implemented simply by the retardation in fuel injection timing,
fuel consumption and exhaust gas (HC) become aggravated, especially
at low speed and low load. Further, there arises a concern about
oil dilution (fuel deposits onto a cylinder wall widely exposed in
a piston descending state, and the fuel deposited on the wall is
mixed into the oil, whereby the oil is diluted).
[0107] Thus, under some circumstances it may be desirable for the
fuel injection timing in the engine 1 to be retarded in a
temperature elevation request event for regeneration of the exhaust
purification device (DPF 11, NOx absorber catalyst 10) as described
above, thereby to elevate the exhaust temperature and to increase
the power output of the engine 1. In addition, the motor 2 is
driven by an excess power output with respect to a requested power
output to generate the power, whereby the high load power
generation operation of the engine 1 is carried out to thereby
elevate the exhaust temperature. That is, the internal combustion
engine 1 and the electric motor 2 undergo the cooperative control
to prevent the battery 4 from being overcharged in the event of
regeneration control. Consequently, the amount of retardation in
the fuel injection timing is maintained to a level that
substantially does not cause, for example, an undesirable
aggravation of the fuel consumption and exhaust gas and oil
dilution. Concurrently, the amount of power generated in the power
generation operation is maintained to a level that does not cause
overcharge, thereby to make it possible to obtain a sufficient
temperature elevation effect. Once again, an example of cooperative
control may be illustrated using the regeneration of the DPF
11.
[0108] FIG. 18 is a control block diagram of the hybrid vehicle.
For convenience, while the actual mechanisms may be somewhat
different as discussed below, the same nomenclature is used between
FIGS. 2 and 18.
[0109] The vehicle includes operation state detecting mechanism BI
for detecting the operation state of the vehicle; operation point
determining mechanism B2 for determining respective operation
points of the engine and motor in accordance with the detection
results; engine control mechanism B3 for controlling the engine in
accordance with a determined engine operation point; and motor
control mechanism B4 for controlling the motor in accordance with a
determined motor operation point.
[0110] More specifically, the operation point determining mechanism
B2 is configured to alter an operation point in accordance with an
operation mode specified by operation mode altering mechanism B5 in
the relation with the regeneration control of the DPF 11. The
operation mode altering mechanism B5 contains information input
from a DPF deposit amount estimating mechanism B6 (sometimes called
the temperature elevation specifying mechanism), DPF temperature
detecting mechanism B7, and charge amount detecting mechanism
B8.
[0111] The DPF deposit amount estimating mechanism B6 estimates a
PM deposit amount in the DPF 11, and determines timing at which the
estimated result is a predetermined value or more to be
regeneration timing, thereby to generate a temperature elevation
request. The DPF deposit amount estimating mechanism B6 uses, for
example, a differential pressure sensor that detects between an
upstream exhaust pressure in the DPF 11 and a downstream exhaust
pressure therein, thereby to estimate a PM deposit amount from the
detected differential pressure and an engine operation state
(volume of exhaust flow or engine speed and load defining the
volume of exhaust flow). Alternatively, the PM deposit amount can
be estimated in such a manner that the amounts of collected PM per
unit time are estimated from the engine operation state, and the
results are integrated.
[0112] The DPF temperature detecting mechanism B7 detects a DPF
temperature T by using, for example, a sensor that detects, for
example, the temperature of a DPF carrier or exhaust temperatures
of a downstream side and/or upstream side of the DPF 11.
[0113] The charge amount detecting mechanism B8 detects a charge
amount SOC in the battery through the integration of charge and
discharge currents by using a current sensor that detects charge
and discharge currents of the battery 4. Normally, the charge
amount SOC is obtained as a ratio (%) with respect to the full
amount of charge.
[0114] A current compensating mechanism B9 is provided in
communication with the motor control mechanism B4. The current
compensating mechanism B9 performs current control to reduce the
power generation efficiency of the motor 2 via an inverter under a
predetermined condition. More specifically, the current
compensating mechanism B9 can reduce the power generation
efficiency by carrying out current compensation via an inverter to
supply AC power corresponding to a phase component with an advance
of an electrical angle of 180 degrees with respect to magnetic
fields of the magnet of the motor 2 (thereby increasing the
amplitude of the AC current).
[0115] Operation modes to be specified by the operation mode
altering mechanism B5 correspondingly to, for example, the state of
the DPF will be described here below.
[0116] The operation modes are a normal mode (M=4), a power
generation amount increase mode (M=5), a power generation amount
restriction mode (M=6), a power generation amount
restriction-plus-current compensation mode (M=7), and a motor
driven travel mode (M=8). The respective modes will be described
here below.
[0117] The normal mode (M=4) is a normal operation mode. In this
mode, a total power output Pt requested for the vehicle is
calculated in accordance with operation state information received
from the operation state detecting mechanism B1. In addition, an
engine power output Pe and a motor power output Pm are determined
from the total power output Pt by using a hybrid power output
(engine/motor power output) distribution table as illustrated in
FIG. 19, which shows a distribution of hybrid power output with
respect to the total power output. Then, the determination results
are supplied for commands to the engine control mechanism B3 and
the motor control mechanism B4.
[0118] In the engine control mechanism B3, an operation point is
determined by using an engine operation point table such as that
illustrated in FIG. 4 in accordance with the determined engine
power output Pe. The operation point table is created by setting
combinations of torques (Te0, Te1, . . . ) and rotational speeds
(Ne0, Ne1, . . . ), which optimize fuel consumption, with respect
to respective engine power output values (Pe0, Pe1, . . . ).
[0119] In the motor control mechanism B4, an operation point is
determined by using a motor operation point table as illustrated in
FIG. 21 in accordance with the determined motor power output Pm0.
The operation point table is created by setting combinations of
torques (Tm0, Tm1, . . . ) and rotational speeds (Nm0, Nm1, . . .
), which optimize fuel consumption, with respect to the respective
motor power output values (Pm0, Pm1, . . . ).
[0120] The power generation amount increase mode (M=5) is an
operation mode for use in the case when a temperature elevation
request for the DPF 11 is present, and the charge amount SOC in the
battery 4 is smaller than a first predetermined value EmL. In this
mode, the engine power output is largely increased to thereby
largely increase the amount of power generated. The mode is thus
set for the reason that the exhaust temperature is raised through a
high load operation of the engine 1 to thereby promote the
elevation of the DPF temperature. As such, the engine power output
Pe and the motor power output Pm are determined from the requested
total power output Pt by using a hybrid power output distribution
table of FIG. 22. Then the determination results are supplied for
commands to the engine control mechanism B3 and the motor control
mechanism B4. In the hybrid power output distribution table as
shown in FIG. 22, the engine power output Pe is set to a relatively
large fixed value Pec in the entire zone. Thereby, in a
low/intermediate power output zone, an excess amount (Pec-Pt) of
the engine power output with respect to the requested total power
output Pt is set to be the amount of power generated in the
motor.
[0121] The power generation amount restriction mode (M=6) is an
operation mode for use in the case when a DPF temperature elevation
request is present, and the battery charge amount SOC is larger
than the first predetermined value EmL and is smaller than a second
predetermined value EmH. In this mode, the amount of power
generated is increased by increasing the engine power output for
exhaust temperature elevation. However, the charge amount SOC is
relatively large, such that the amount of power generated is
restricted, and the fuel injection timing is retarded corresponding
to the restriction, thereby to elevate the exhaust temperature.
More specifically, compared to the case of the power generation
amount increase mode (M=5), in the power generation amount
restriction mode (M=6), the fuel injection timing is retarded, and
the power output increase amount in the internal combustion engine
or the power generation amount corresponding to the power output
increase in the engine is reduced. In this event, a power output
increase amount in the internal combustion engine or the power
generation amount corresponding to the power output increase in the
engine is determined so that the amount of retardation in the fuel
injection timing falls within a range of amount of retardations
that does not cause exhaust gas aggravation or oil dilution. As
such, an engine power output Pe and a motor power output Pm are
determined from a requested total power output Pt by using a hybrid
power output distribution table as illustrated in FIG. 23. Then,
the determined power outputs Pe and Pm are supplied for commands to
the engine control mechanism B3 and the motor control mechanism B4.
In the hybrid power output distribution table of FIG. 23, the
engine power output Pe is set to a relatively small fixed value Pes
in the entire zone. Thereby, in a low power output zone, an excess
amount (Pes-Pt) of the engine power output with respect to the
requested total power output Pt is set to be an amount of power
generated in the motor.
[0122] The engine operation point table to be used in the power
generation amount restriction mode (M=6) can be identical to the
table of FIG. 20. In this case, however, there occurs no operation
such as that, as shown in FIG. 24, in a low speed-plus-low load
region (hatched range) in which, for example, oil dilution and HC
aggravation tend to be caused by the retardation in the fuel
injection timing.
[0123] Further, as shown in FIG. 25, the amount of retardation in
the fuel injection timing (with respect to the power generation
amount increase mode (M=5)) in the power generation amount
restriction mode (M=6) is reduced toward the higher load side in
correspondence to the rotational speed and the torque.
[0124] The power generation amount restriction-plus-current
compensation mode (M=7) is an operation mode for use in the case
where a DPF temperature elevation request is present, the battery
charge amount SOC is larger than the second predetermined value
EmH, and the DPF temperature T is relatively low (in the case where
the catalyst is inactive). In this mode, the power generation
amount has to be further restricted, so that current compensation
is carried out in addition to the operation in the power generation
amount restriction mode (M=6).
[0125] More specifically, in the event of power generation, the
power generation efficiency of the motor 2 is reduced by carrying
out the current compensation via the inverter 3 to supply AC power
corresponding to a phase component with an advance of an electrical
angle of 180 degrees with respect to magnetic fields of the magnet
of the motor 2 (thereby increasing the amplitude of the AC
current). In other words, in the event of control of the AC current
by using the inverter 3, of the amplitudes of components with a
high efficient (loss-free) phase and a low efficient phase (D-axis
phase) of the AC current, the amplitude of components with the low
efficient phase is controlled to be large than usual. Thereby, the
power generation efficiency is reduced, and the energy is converted
to heat.
[0126] In this case, by using the hybrid power output distribution
table of FIG. 23, a current compensation value .DELTA.Id (D-axis
current compensation value) is preferably determined corresponding
to a motor power generation amount .DELTA.P (=Pes-Pt) at which the
engine power output is higher than the requested total power output
Pt. More specifically, as shown in FIG. 26, the current
compensation value .DELTA.Id is preferably set to be larger as the
motor power generation amount AP becomes larger.
[0127] The motor driven travel mode (M=8) is an operation mode for
use in the case where a DPF temperature elevation request is
present, the charge amount SOC in the battery is higher than the
second predetermined value EmH, and the DPF temperature T is
relatively higher (in the case where the catalyst is active). In
this mode, the power output is obtained only from the motor 2
(motor power output: 100%). More specifically, the battery charge
amount SOC is reduced by the motor driven travel, and concurrently,
the engine 1 is draggedly rotated ("dragged," herein below) along
at a predetermined rotational speed, whereby air for combustion is
supplied to the DPF 11. Oxygen contained in the supplied air reacts
with PM in the DPF 11 and causes combustion, thereby making it
possible to elevate the temperature of the exhaust purification
device. In this case, the predetermined rotational speed is a
rotational speed at which a DPF-temperature elevatable amount of
air is supplied, and is set to be not excessively high to the
extent of causing air cooling.
[0128] Under a predetermined condition where the temperature is
reduced by air supply to the DPF 11, however, (where the DPF
temperature is relatively low and the temperature is reduced by air
cooling) and in the event of the motor driven travel, any one of
control processes (1) to (3) described here below may be
implemented.
[0129] (1) The drag rotation is cancelled, and the engine 1 is
stopped, thereby to stop air supply to the DPF 11. More
specifically, as shown in FIG. 27, while the engine 1 is dragged by
bringing a clutch 6e into engagement (as illustrated in FIG. 1)
only when the DPF temperature is not lower than a predetermined
value Tc, the engine 1 is stopped by releasing the clutch 6e when
the DPF temperature is lower than the predetermined value Tc.
[0130] (2) While the engine 1 is dragged, the air supply to the DPF
11 is reduced by setting a throttle valve in an intake system to a
full open position in a fuel cut state.
[0131] (3) While the engine 1 is dragged, the air supply to the DPF
11 is reduced in such a manner that an exhaust gas recirculation
(EGR) valve provided in an EGR passageway for returning the exhaust
gas to the intake system is set to a full open position in a fuel
cut state.
[0132] FIG. 28 is a flow chart illustrating a flow of control. In
step A1, the process determines the presence or absence of a DPF
temperature elevation command (regeneration request). More
specifically, the process reads a PM deposit amount (estimated
value) in the DPF 11, which is calculated in a different routine.
Then, the process determines whether or not the read value is
greater than or equal to a predetermined value for regeneration
timing determination.
[0133] If a DPF temperature elevation command is absent as a result
of the determination in step A1, the process proceeds to step A1.
In step A1, the mode is set to and maintained in the normal mode
(M=4).
[0134] If a DPF temperature elevation command is present as a
result of the determination in step A1, the process proceeds to
step A2. In step A2, it is determined whether or not the battery
charge amount SOC is larger than a first predetermined value EmL.
The first predetermined value EmL is a value set to a level on a
relatively low side, and a value lower than the level does not
cause over discharge even when the battery is sufficiently
charged.
[0135] If SOC<Eml (if SOC is a low level) as a result of the
determination in step A2, the process proceeds to step A9. In step
A9, the mode is set to the power generation amount increase mode
(M=5).
[0136] If SOC>EmL as a result of the determination in step A2,
the process proceeds to step A3, in which the process determines
whether or not the battery charge amount SOC is higher than a
second predetermined value EmH. The second predetermined value EmH
is set to a level on a relatively high side (EmH>EmL), and a
level higher than the level is determined to be a level at which
the power generation is desired to be stopped as early as
possible.
[0137] If SOC<EmH, that is, if EmL<SOC<EMH (i.e., if SOC
is an intermediate level as a result of the determination in step
A3, the process proceeds to step A6. Unless the present mode is the
motor driven travel mode (M=8) as a result of the determination in
step A6, the process proceeds to step A8, in which the mode is set
to the power generation amount restriction mode (M=6). Step A6 will
be described further below.
[0138] Alternately, if SOC>EmH (that is, if SOC is the high
level) as a result of the determination in step A3, the process
proceeds to step A4, wherein the process determines whether or not
the DPF temperature is a catalyst activation temperature or
higher.
[0139] If SOC is at a high level and the DPF temperature is low (if
the DPF 11 is in an inactive state), the process proceeds from step
A4 to step A7. In step A7, the process sets the mode to the power
generation amount restriction-plus-current compensation mode
(M=7).
[0140] Alternately, if SOC is the high level and the DPF
temperature is high (if the DPF 11 is in an active state), the
process proceeds from step A4 to step A5, in which the mode is set
to the motor driven travel mode (M=8).
[0141] Thus, if the exhaust purification device is inactive, then
current control is carried out to reduce the power generation
efficiency of the motor 2. Alternately, if the exhaust purification
device is active, the hybrid vehicle is driven only or exclusively
by the power output of the motor 2, and the internal combustion
engine 1 is driven (rotated). Thereby, the air is supplied to the
exhaust purification device.
[0142] Step A6 will now be further described. As described above,
as SOC reaches a high level, the DPF temperature is at a high
temperature state (active state), and the mode is set in step A5 to
the motor driven travel mode (M=8). Thereafter, SOC is reduced to
an intermediate level by the SOC reduction due to the motor driven
travel operation, and the process proceeds from step A3 to step A6.
As a result of the determination in step A6, "M=8" is detected as a
mode, so that the process proceeds to step A4. If the DPF
temperature is in the high temperature state in step A4, the motor
driven travel mode (M=8) set in step A5 is continued. Alternately,
if the DPF temperature is in the low temperature state, the mode is
shifted to the power generation amount restriction-plus-current
compensation mode (M=7) corresponding to step A7. In the event that
SOC remains in the intermediate level in the state where a
temperature elevation command is present, the process again
proceeds to from step A3 to step A6 in the next operation cycle. As
a result of the determination in step A6, "M=4" is detected, so
that the process proceeds to step A8, in which the mode is set to
the engine power output increase mode (M=3).
[0143] The flow control of FIG. 28 is now discussed with reference
to timing charts of FIGS. 29 and 30. First, the process related to
the timing chart of FIG. 29 is addressed. At time t1, a temperature
elevation command for DPF regeneration turns ON. In this event, if
the battery charge amount SOC is smaller than the first
predetermined value EmL, the mode is shifted from the normal mode
(M=4) to the power generation amount increase mode (M=5). Thereby,
the motor 2 is driven by the engine 1 to generate the power without
retardation in the fuel injection timing in the engine 1.
Concurrently, the exhaust temperature is elevated by the high load
power generation operation of the engine 1, thereby to elevate the
DPF temperature T. The amount of power generated in this case is
charge into the battery 4.
[0144] If the battery charge amount SOC exceeds the first
predetermined value EmL at time t2, the mode is shifted to the
power generation amount restriction mode (M=6). Thereby, the fuel
injection timing in the engine 1 is retarded, and the motor 2 is
driven by the engine 1 to generate the power. Then, the exhaust
temperature is elevated by both the engine 1 and motor 2, thereby
to elevate the DPF temperature T. The amount of power generated in
this case can be reduced corresponding to the temperature elevated
by the retardation in the fuel injection timing.
[0145] Suppose that, at time t3, the battery charge amount SOC has
reached the second predetermined value EmH and the DPF temperature
T has reached the catalyst activation temperature. In this event,
the mode is shifted to the motor driven travel mode (M=8).
Thereafter, even if the battery charge amount SOC reduces, the
motor driven travel mode (M=8) is maintained as long as the value
is not lower than the first predetermined value EmL. Thereby, the
battery charge amount SOC is reduced by the motor driven travel
operation, the engine 1 is dragged along by the motor 2 at a
predetermined rotational speed, and the air for combustion is
supplied to the DPF 11, whereby the temperature elevation is
continued.
[0146] When the temperature elevation command turns OFF at time t4,
the mode is shifted to the normal mode (M=4).
[0147] The case of the timing chart of FIG. 30 will now be
described.
[0148] In the same manner as in the case of FIG. 29, the mode is
shifted from the normal mode (M=4) to the power generation amount
increase mode (M=5) at time t1, and the mode is shifted to the
power generation amount restriction mode (M=6) at time t2.
[0149] However, if at time t3, the battery charge amount SOC has
reached the second predetermined value EmH, but the DPF temperature
T has not yet reached the catalyst activation temperature, the mode
is shifted to the power generation amount restriction-plus-current
compensation mode (M=7). Thereby, the fuel injection timing in the
engine 1 is retarded, the motor 2 is driven by the engine 1 to
thereby generate the power, and current compensation is carried out
to reduce the power generation efficiency of the motor 2.
Consequently, while increase in the battery charge amount SOC is
restrained, and concurrently, the requested temperature elevation
can be accomplished.
[0150] At time t4, the mode is shifted to the normal mode (M=4)
when the temperature elevation command turns OFF.
[0151] As described above, according to the present embodiment, in
response to a temperature elevation request for the DPF 11, the
fuel injection timing in the engine 1 is retarded and the motor 2
is driven by the engine 1 to generate the power. Consequently, the
amount of retardation in the fuel injection timing is restrained to
a level that substantially does not cause, for example, aggravation
of the fuel consumption and exhaust gas. Further, while the power
generation amount in the power generation operation is restrained
that does not cause overcharging, sufficient temperature elevation
effects can be secured.
[0152] Further, according to the present embodiment, the amount of
power generated in the power generation is set to a range in which
the engine power output is maintained at a sufficiently large level
that does not cause aggravation of the exhaust gas due to the
retardation in the fuel injection timing. Consequently, significant
aggravation of the exhaust gas (HC) or oil dilution can be securely
restrained, and the amount of charge can be reduced.
[0153] Further, according to the present embodiment, the
configuration includes a mechanism that detects the battery charge
amount SOC. In the configuration, if the battery charge amount SOC
is lower than the first predetermined value EmL when a DPF
temperature elevation request is present, the motor 2 is driven by
the engine 1 to generate the power without retardation in the fuel
injection timing in the engine 1. On the other hand, if the battery
charge amount SOC is higher than the first predetermined value EmL,
and the motor 2 is driven by the engine 1 to generate the power.
Thus, the amount of power generated in this case is reduced to be
smaller than the amount of power generated in the case where the
battery charge amount SOC is lower than the first predetermined
value EmL. This makes it possible to implement appropriate control
of the power generation amount corresponding to the battery charged
state.
[0154] Further, according to the present embodiment, regardless of
variation in the requested total power output Pt0, the power
generation is performed by controlling the engine power output Pe
to be the fixed value. When the battery charge amount SOC is higher
than the first predetermined value EmL, the constant value is
reduced to be smaller than the constant value in the case where the
battery charge amount SOC is lower than the first predetermined
value EmL (the fixed value Pes in the case of SOC larger than EmL
is reduced to be smaller than the fixed value Pec in the case of
SOC lower than EmL). Thereby, power generation is performed in a
lower power output zone while the motor power output ratio is
increased to increase the number of discharge instances in an
intermediate/high power output zone. Consequently, aggravation of
the exhaust gas (HC) and oil dilution due to the injection timing
retardation in the low power output zone can be restrained, and the
exhaust temperature can be elevated.
[0155] Further, according to the present embodiment, in the event
of power generation, current control is carried out to reduce the
power generation efficiency of the motor 2. Consequently, while the
temperature elevation effects are enhanced by increasing the engine
load, the amount of charge into the battery is reduced to thereby
make it possible to prevent overcharging.
[0156] Further, according to the present embodiment, when the
battery charge amount SOC is higher than the second predetermined
value EmH set higher than the first predetermined value EmL in the
presence of a temperature elevation request for the exhaust
purification device (DPF), the fuel injection timing in the engine
1 is retarded. In addition, the motor 2 is driven by the engine 1
to generate the power, and current control is carried out to reduce
the power generation efficiency of the motor 2. Consequently, in
the state where the charge amount SOC is high, the temperature
elevation effects are enhanced by increasing the engine load, the
amount of charge into the battery is reduced to thereby make it
possible to prevent overcharging.
[0157] Further, according to the present embodiment, the current
control is carried out corresponding to the power generation amount
.DELTA.P (=Pes-Pt) at which the engine power output is higher than
the requested total power output Pt. In this manner, the power
generation efficiency is reduced to be lower as the excess amount
of generated power is larger, thereby to prevent the amount of
generated power being used for discharging. In addition, when the
excess amount of generated power is small, heat generation in the
motor 2 can be prevented by enhancing the power generation
efficiency
[0158] Further, according to the present embodiment, when the
battery charge amount SOC is higher than the second predetermined
value EmH set higher than the first predetermined value EmL in the
presence of a temperature elevation request for the exhaust
purification device (DPF), the operation is shifted to the motor
driven travel operation in which the power output is obtained only
from the motor 2. Concurrently, the engine 1 is dragged by the
motor 2 at the predetermined rotation speed to supply the
combustion air (oxygen) to the exhaust purification device (DPF).
Thereby, while the charge amount SOC is reduced by the motor driven
travel operation, combustion (PM combustion) can be promoted, and
either temperature elevation can be promoted or temperature
reduction can be restrained.
[0159] Further, according to the present embodiment, the
predetermined rotational speed is set to the rotational speed at
which the amount of air capable of elevating the temperature of the
exhaust purification device (DPF) can be supplied. Thereby, it is
possible to prevent an event where the rotational speed is
excessively high to the extent of causing air cooling.
Consequently, temperature elevation can be promoted
effectively.
[0160] Further, according to the present embodiment, under the
predetermined condition where the temperature is reduced by air
supply to the exhaust purification device (DPF) (for example, the
condition where either the DPF is inactive or the PM deposit amount
corresponding to the DPF temperature is not larger than the
predetermined value) during the motor driven travel operation, the
engine 1 is stopped by canceling the drag rotation (by releasing
the clutch) to stop air supply to the exhaust purification device
(DPF). Thereby, while the charge amount SOC is reduced by the motor
driven travel operation, heat insulation of the exhaust
purification device (DPF) can be implemented by cutting out gases
that can serve as coolant.
[0161] Further, according to the present embodiment, under the
predetermined condition where the temperature is reduced by air
supply to the exhaust purification device (DPF) during the motor
driven travel operation, the throttle valve in the engine I is set
to the full open position to reduce the amount of air supply to the
exhaust purification device (DPF). In this manner, while the charge
amount SOC is reduced by the motor driven travel operation, heat
insulation of the exhaust purification device (DPF) can be
implemented by either cutting out or reducing gases that can serve
as coolant.
[0162] Additionally, according to the present embodiment, under the
predetermined condition where the temperature is reduced by air
supply to the exhaust purification device (DPF) during the motor
driven travel operation, the EGR valve in the engine 1 is set to
the full open position to reduce the amount of air supply to the
exhaust purification device (DPF). In this manner, while the charge
amount SOC is reduced by the motor driven travel operation, heat
insulation of the exhaust purification device (DPF) can be
implemented by either cutting out or reducing gases that can serve
as coolant.
[0163] While the embodiment first discussed with respect to FIG. 18
has been described with reference to the parallel hybrid vehicle
(shown in FIG. 1), it is adaptable as well to a series hybrid
vehicle.
[0164] FIG. 15 is a system diagram of a series hybrid vehicle to
which the present embodiment is adaptable.
[0165] In the system, an output shaft of an engine 1 and an output
shaft of a motor 2 are coaxial and directly coupled together. The
single output shaft is coupled to an input shaft of a final
reduction gear device 7 through a transmission (belt continuous
variable transmission (CVT)) 5 and a clutch 6.
[0166] The embodiment is adaptable as well to the hybrid vehicle of
the above-described type. In this case, however, the engine 1 and
the motor 2 have the same rotational speed. As such, by using the
engine operation point table of FIG. 20, the engine control
mechanism B3 determines respective engine operation points
(rotational speeds Ne0 and Ne1, and torques Te0 and Te1) from the
requested engine power outputs Pe0 and Pe1. However, the motor
control mechanism B4 uses the operation point table of FIG. 16 in
place of the motor operation point table of FIG. 21. The engine 1
and the motor 2 have the same rotational speed. For this reason,
when the request motor power outputs are Pm0 and Pm1 in the event
of the rotational speeds of Ne0 and Ne1, motor torques are
determined to be Tm0=Pm0/Ne0 and Tm1=Pm1/Ne1, respectively, as
shown in FIG. 16.
[0167] Thus, the embodiment discussed in FIG. 18 has been described
with reference to the case where the exhaust purification device is
the DPF, and PM deposited therein is burned out under the
predetermined regeneration condition. However, the embodiment can
be applied as well to the case where the exhaust purification
device is a NOx absorber catalyst, and sulfur deposited therein is
burned out under a predetermined regeneration condition. However,
the characteristics in FIG. 27 in the motor driven travel mode
(M=8) are adapted only during the DPF regeneration.
[0168] The preceding description has been presented only to
illustrate and describe exemplary embodiments of the claimed
invention. It is not intended to be exhaustive or to limit the
invention to any precise form disclosed. It will be understood by
those skilled in the art that various changes may be made and
equivalents may be substituted for elements thereof without
departing from the scope of the invention. In addition, many
modifications may be made to adapt a particular situation or
material to the teachings of the invention without departing from
the essential scope. Therefore, it is intended that the invention
not be limited to the particular embodiment disclosed as the best
mode contemplated for carrying out this invention, but that the
invention will include all embodiments falling within the scope of
the claims. The invention may be practiced otherwise than is
specifically explained and illustrated without departing from its
spirit or scope. The scope of the invention is limited solely by
the following claims.
* * * * *