U.S. patent application number 12/308706 was filed with the patent office on 2010-03-11 for control device for hybrid vehicle and control method therefor.
This patent application is currently assigned to TOYOTA JIDOSHA KABSHIKI KAISHA. Invention is credited to Makoto Ogiso.
Application Number | 20100063659 12/308706 |
Document ID | / |
Family ID | 38896730 |
Filed Date | 2010-03-11 |
United States Patent
Application |
20100063659 |
Kind Code |
A1 |
Ogiso; Makoto |
March 11, 2010 |
CONTROL DEVICE FOR HYBRID VEHICLE AND CONTROL METHOD THEREFOR
Abstract
In a hybrid vehicle that includes an internal combustion engine
(1) in conjunction with an electric motor (2), when one of a
process of regenerating the purification capacity of an exhaust gas
purifying device (10) and a process of charging a battery (7) is
performed (S102), the presence or absence of a request to perform
the other process is determined (S103) so that the two processes
may be performed as simultaneously as possible to reduce
deterioration in driveability and in the fuel efficiency as much as
possible.
Inventors: |
Ogiso; Makoto; (Mishima-shi,
JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 320850
ALEXANDRIA
VA
22320-4850
US
|
Assignee: |
TOYOTA JIDOSHA KABSHIKI
KAISHA
TOYOTA-SHI
JP
|
Family ID: |
38896730 |
Appl. No.: |
12/308706 |
Filed: |
September 25, 2007 |
PCT Filed: |
September 25, 2007 |
PCT NO: |
PCT/IB2007/002782 |
371 Date: |
December 22, 2008 |
Current U.S.
Class: |
701/22 ;
180/65.265; 60/285; 60/286; 60/295; 60/716 |
Current CPC
Class: |
B60Y 2300/476 20130101;
Y02T 10/12 20130101; Y02T 10/70 20130101; B60L 50/61 20190201; B60W
20/00 20130101; F02D 41/0245 20130101; B60W 10/06 20130101; Y02T
10/26 20130101; Y02T 10/62 20130101; Y02T 10/705 20130101; Y02T
10/7077 20130101; F02D 41/029 20130101; F02D 2041/026 20130101;
Y02T 10/7044 20130101; F02D 41/028 20130101; Y02T 10/6286 20130101;
Y02T 10/6217 20130101; B60L 2270/12 20130101; Y02T 10/40 20130101;
B60W 10/26 20130101; Y02T 10/54 20130101; Y02T 10/6221 20130101;
B60L 7/14 20130101; B60L 50/16 20190201; B60W 10/08 20130101; B60W
20/15 20160101; Y02T 10/7005 20130101; F02D 41/0275 20130101; B60K
6/48 20130101; Y02T 10/7072 20130101 |
Class at
Publication: |
701/22 ; 60/295;
60/286; 60/285; 60/716; 180/65.265 |
International
Class: |
G06F 19/00 20060101
G06F019/00; F01N 3/023 20060101 F01N003/023; F01N 9/00 20060101
F01N009/00; F02D 43/00 20060101 F02D043/00; F02B 73/00 20060101
F02B073/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 26, 2006 |
JP |
2006-260691 |
Claims
1-5. (canceled)
6. A control device for a hybrid vehicle that includes: an internal
combustion engine; an electric motor operable by electric power to
assist the output power of the internal combustion engine; an
exhaust gas purifying device, provided in an exhaust passage,
through which exhaust gas from the internal combustion engine flows
to purify the exhaust gas flowing through the exhaust passage, the
purification capacity of the exhaust gas purifying device being
regenerated by a regenerating process; a battery for serving at
least as a source of electric power to operate the electric motor
and charged by electric power supplied during a charging process;
and a power generator for generating electric power proportional to
the engine load or engine speed and supplying the electric power to
the battery during the charging process; the control device
comprising: a regenerating portion that performs the regenerating
process by increasing the engine load and/or engine speed based on
a request to perform the regenerating process from the exhaust gas
purifying device; a charging portion that performs the charging
process by increasing the engine load and/or engine speed based on
a request to perform the charging process from the battery, and at
least one of: a first multitasking portion that executes the
regenerating process and determines whether execution of the
charging process is requested when execution of the regenerating
process is requested, and a second multitasking portion that
executes the charging process and determines whether execution of
the regenerating process is requested when execution of the
charging process is requested, wherein the first multitasking
portion determines whether execution of the charging process is
requested after relaxing a prescribed first execution condition for
determining whether execution of the charging process is requested,
and wherein the second multitasking portion determines whether
execution of the regenerating process is requested after relaxing a
prescribed second execution condition for determining whether
execution of the regenerating process is requested.
7. The control device for a hybrid vehicle according to claim 6,
wherein the first execution condition is satisfied when the amount
of charge in the battery is equal to or smaller than a threshold
charge amount, and the first multitasking portion determines the
presence or absence of a request to perform the charging process
after relaxing the prescribed first execution condition by
increasing the value of the threshold charge amount.
8. The control device for a hybrid vehicle according to claim 6,
wherein the second execution condition is satisfied when the amount
of matter accumulated in the exhaust gas purifying device is equal
to or greater than a threshold amount, and the second multitasking
portion determines the presence or absence of a request to perform
a regenerating process after relaxing the prescribed second
execution condition by decreasing the value of the threshold
amount.
9. A control method for a hybrid vehicle that includes: an internal
combustion engine; an electric motor operable by electric power to
assist the output power of the internal combustion engine; an
exhaust gas purifying device, provided in an exhaust passage,
through which exhaust gas from the internal combustion engine flows
to purify the exhaust gas flowing through the exhaust passage, the
purification capacity of the exhaust gas purifying device being
regenerated by a regenerating process; a battery for serving at
least as a source of electric power to operate the electric motor
and charged by electric power supplied during a charging process; a
power generator for generating electric power proportional to the
engine load or engine speed and supplying the electric power to the
battery during the charging process; a regenerating portion for
performing the regenerating process by increasing the engine load
and/or engine speed based on a request to perform the regenerating
process from the exhaust gas purifying device; and a charging
portion for performing the charging process by increasing the
engine load and/or engine speed based on a request to perform the
charging process from the battery, the control method comprising at
least one of: executing the regenerating process and determining
whether execution of the charging process is requested when
execution of the regenerating process is requested, wherein the
first multitasking portion determines whether execution of the
charging process is requested after relaxing a prescribed first
execution condition for determining whether execution of the
charging process is request, and executing the charging process and
determining whether execution of the regenerating process is
requested when execution of the charging process is requested,
wherein the second multitasking portion determines whether
execution of the regenerating process is requested after relaxing a
prescribed second execution condition for determining whether
execution of the regenerating process is requested.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a control device for a
hybrid vehicle and a control method therefor, and, more
particularly, to a control device for regenerating the purification
capacity of an exhaust gas purifying device and for charging a
battery, and a control method therefor.
[0003] 2. Description of the Related Art
[0004] In recent years, hybrid vehicles which have an internal
combustion engine combined with an electric motor and runs on the
output power from the internal combustion engine in conjunction or
combination with the output power from the electric motor are in
practical use. In such hybrid vehicles, the internal combustion
engine is operated intermittently as needed and is selectively
operable in high-efficiency operating ranges. Therefore, the hybrid
vehicles have advantages in terms of fuel efficiency and exhaust
gas purification performance as compared with vehicles, which run
on only the output power from an internal combustion engine.
[0005] However, even the hybrid vehicles cannot run without
emitting exhaust gas derived from the operation of the internal
combustion engine, and require an exhaust gas purifying device for
purifying the exhaust gas from the internal combustion engine.
[0006] As the exhaust gas purifying device, a storage-reduction
type NOx catalyst for purifying NOx in exhaust gas from an internal
combustion engine (which is hereinafter referred to also as "NOx
catalyst") and a particulate filter for purifying particulate
matter in exhaust gas (which is hereinafter referred to also as
"filter") are known.
[0007] As for the NOx catalyst, a process in which the temperature
of the NOx catalyst bed is increased and a reducing agent is
supplied to the NOx catalyst (which is hereinafter referred to as
"SOx regenerating process") is performed to eliminate SOx
poisoning, which is a phenomenon where SOx in the exhaust gas is
stored in the NOx catalyst and reduces the storage capacity of the
NOx catalyst.
[0008] As for the filter, when a large amount of collected
particulate matter (PM) is accumulated, the filter is clogged and
the back pressure in the exhaust gas is increased to the extent
that the engine performance is reduced. Therefore, a process of
increasing the temperature of the filter is performed by, for
example, increasing the temperature of exhaust gas to be introduced
into the filter to remove the collected particulate matter by
oxidation (which is hereinafter referred to as "PM regenerating
process").
[0009] In the SOx regenerating process and the PM regenerating
process, the engine load or the engine speed is set to a value
greater than that during normal operation in order to increase the
temperature of exhaust gas.
[0010] In addition, the above hybrid vehicles require a process of
charging a battery for serving at least as an electric power source
of the electric motor. In the battery charging process, the engine
load or the engine speed is set to a value greater than that during
normal operation as in the SOx regenerating process and the PM
regenerating process. Therefore, every time any of the above
processes is performed, the driveability and the fuel efficiency of
the hybrid vehicle as a system may deteriorate.
SUMMARY OF THE INVENTION
[0011] The present invention provides for a process of charging a
battery and a process of regenerating the purification capacity of
an exhaust gas purifying device to be performed more efficiently in
a hybrid vehicle that runs using an internal combustion engine in
conjunction or combination with an electric motor to improve the
driveability or the fuel efficiency of the hybrid vehicle.
[0012] One aspect of the present invention is that, in a hybrid
vehicle, when one of a process of regenerating the purification
capacity of an exhaust gas purifying device and a process of
charging a battery is performed, the presence or absence of a
request to perform the other process is determined so that the two
processes can be performed as simultaneously as possible to reduce
the opportunities for deterioration of the driveability and the
fuel efficiency as much as possible.
[0013] More specifically, a first aspect of the present invention
includes: an internal combustion engine; an electric motor operable
by electric power to assist the output power of the internal
combustion engine; an exhaust gas purifying device, provided in an
exhaust passage, through which exhaust gas from the internal
combustion engine flows to purify the exhaust gas flowing through
the exhaust passage, the purification capacity of the exhaust gas
purifying device being regenerated by a regenerating process; a
battery for serving at least as a source of electric power to
operate the electric motor and charged by electric power supplied
during a charging process; a power generator for generating
electric power proportional to the engine load or engine speed and
supplying the electric power to the battery during the charging
process; regenerating means for performing the regenerating process
by increasing the engine load and/or engine speed based on a
request to perform the regenerating process from the exhaust gas
purifying device; and charging means for performing the charging
process by increasing the engine load and/or engine speed based on
a request to perform the charging process from the battery, and
further includes at least either first multitasking means for
performing the regenerating process and determining the presence or
absence of a request to perform the charging process when there is
a request to perform the regenerating process, or second
multitasking means for performing the charging process and
determining the presence or absence of a request to perform the
regenerating process when there is a request to perform the
charging process.
[0014] A second aspect of the present invention includes: an
internal combustion engine; an electric motor operable by electric
power to assist the output power of the internal combustion engine;
an exhaust gas purifying device, provided in an exhaust passage,
through which exhaust gas from the internal combustion engine flows
to purify the exhaust gas flowing through the exhaust passage, the
purification capacity of the exhaust gas purifying device being
regenerated by a regenerating process; a battery for serving at
least as a source of electric power to operate the electric motor
and charged by electric power supplied during a charging process; a
power generator for generating electric power proportional to the
engine load or engine speed and supplying the electric power to the
battery during the charging process; regenerating means for
performing the regenerating process by increasing the engine load
and/or engine speed based on a request to perform the regenerating
process from the exhaust gas purifying device; and charging means
for performing the charging process by increasing the engine load
and/or engine speed based on a request to perform the charging
process from the battery, and further includes at least either
performing the regenerating process and determining the presence or
absence of a request to perform the charging process when there is
a request to perform the regenerating process, or performing the
charging process and determining the presence or absence of a
request to perform the regenerating process when there is a request
to perform the charging process.
[0015] In a hybrid vehicle, the process of charging a battery and
the process of regenerating the purification capacity of an exhaust
gas purifying device must be performed. In the process of charging
the battery, the engine load and/or engine speed are increased to
increase the electricity that is generated by the power generator.
Then, the battery is switched from a discharging state to a
charging state and the electric power generated by the power
generator is supplied to the battery. In the process of
regenerating the purification capacity of the exhaust gas purifying
device (more specifically, a PM regenerating process or an SOx
regenerating process), the engine load and/or engine speed may be
also increased to increase the temperature of exhaust gas in order
to increase the temperature of the exhaust gas purifying
device.
[0016] When the process of charging the battery and the process of
regenerating the purification capacity of the exhaust gas purifying
device are performed independently, the driveability or the fuel
efficiency is adversely affected when either processes is performed
and each process cannot be performed efficiently.
[0017] The control device for a hybrid vehicle of the present
invention further includes at least either of first multitasking
means for performing a PM regenerating process or SOx regenerating
process, when there is a request to perform a PM regenerating
process or SOx regenerating process, and determining the presence
or absence of a request to perform a battery charging process, and
second multitasking means for performing a battery charging
process, when there is a request to perform a battery charging
process, and determining the presence or absence of a request to
perform a PM regenerating process or SOx regenerating process.
[0018] Therefore, since the energy increased by increasing the
engine load and/or engine speed can be used for both the PM
regenerating process or the SOx regenerating process and the
battery charging process, the energy can be used effectively. As a
result, the driveability and the fuel efficiency of the hybrid
vehicle are improved.
[0019] In the aspect of the present invention, the first
multitasking means may determine the presence or absence of a
request to perform the charging process after relaxing a prescribed
first execution condition to determine the presence or absence of a
request to perform the charging process. In addition, the second
multitasking means may determine the presence or absence of a
request to perform the regenerating process after relaxing a
prescribed second execution condition to determine the presence or
absence of a request to perform the regenerating process.
[0020] When the PM regenerating process or the SOx regenerating
process is performed, it is determined whether a request for the
battery charging process has been issued. At this time, the first
execution condition to determine whether to perform the battery
charging process is relaxed. In other words, a state in which a
request for the battery charging process is likely to be issued is
established.
[0021] Similarly, when a battery charging process is performed, it
is determined whether a request for the PM regenerating process or
SOx regenerating process has been issued. At this time, the second
execution condition to determine whether to issue a request for the
PM regenerating process or SOx regenerating process is relaxed to
establish a state in which a request for the PM regenerating
process or SOx regenerating process is likely to be issued.
[0022] Therefore, the possibility that the battery charging process
and the PM regenerating process or SOx regenerating process are
performed simultaneously may be increased, and the driveability and
the fuel efficiency of the hybrid vehicle can be improved more
reliably.
[0023] The first execution condition is that the amount of charge
in the battery is equal to or smaller than a prescribed charge
amount, and the first multitasking means may determine the presence
or absence of a request to perform the charging process after
relaxing the prescribed first execution condition by increasing the
value of the prescribed charge amount. The second execution
condition is that the amount of matter to be purified accumulated
in the exhaust gas purifying device is equal to or greater than a
prescribed amount of accumulated matter, and the second
multitasking means may determine the presence or absence of a
request to perform a regenerating process after relaxing the
prescribed second execution condition by decreasing the value of
the prescribed amount of accumulated matter.
[0024] The means for solving the problem of the present invention
can be used in combination with one another if at all possible.
[0025] The present invention improves the driveability or the fuel
efficiency of a hybrid vehicle that runs using an internal
combustion engine in conjunction with an electric motor by allowing
a process of charging a battery and a process of regenerating the
purification capacity of an exhaust gas purifying device to be
performed more efficiently in the hybrid vehicle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The foregoing and further features and advantages of the
invention will become apparent from the following description of
example embodiments with reference to the accompanying drawings,
wherein like numerals are used to represent like elements, and
wherein:
[0027] FIG. 1 illustrates the general configuration of a hybrid
vehicle according to first and second embodiments of the present
invention.
[0028] FIG. 2 shows a flowchart of a battery charging routine 1 in
the first embodiment of the present invention.
[0029] FIG. 3 shows a flowchart of a battery charging routine 2 in
the first embodiment of the present invention.
[0030] FIG. 4 shows a flowchart of a PM regenerating routine 1 in
the second embodiment of the present invention.
[0031] FIG. 5 shows a flowchart of a PM regenerating routine 2 in
the second embodiment of the present invention.
DETAILED DESCRIPTION OF EMBODIMENTS
[0032] FIG. 1 illustrates the general configuration of a hybrid
vehicle according to first and second embodiments of the present
invention. The hybrid vehicle has an engine 1 and a motor 2 as
driving sources.
[0033] The motor 2 is constituted as, for example, an AC motor, and
has an output shaft connected to driving wheels 4 as a load via a
reduction gear 3 so that the driving wheels 4 can be rotated by
driving the motor 2. In addition, when the rotational energy of the
driving wheels 4 is used to cause the motor 2 to generate
electricity, electrical energy can be stored in a battery 7.
[0034] The engine 1 is an internal combustion engine that includes
an output shaft connected to the driving wheels 4 via a power
distribution mechanism 5 and a reduction gear 3 so that the driving
wheels 4 can be also rotated by driving the engine 1. A generator 6
is constituted as, for example, an AC power generator, and has a
rotating shaft connected to the output shaft of the engine 1 via
the power distribution mechanism 5. The driving energy of the
engine 1 can be therefore converted into electrical energy, and the
electrical energy can be stored in the battery 7 or used to drive
the motor 2. An inverter 8 is provided among the generator 6, the
motor 2 and the battery 7, and the inverter 8 controls electric
power. The battery 7 is provided with a charge amount sensor 15 for
detecting the amount of charge in the battery.
[0035] This hybrid vehicle also has an exhaust pipe 9 connected to
the engine 1 via an exhaust manifold, and a DPNR 10 in which a
storage-reduction type NOx catalyst (which is hereinafter referred
to as "NOx catalyst") for purifying NOx in exhaust gas from the
engine 1 and a filter for collecting particulate matter in the
exhaust gas are combined is provided in the exhaust pipe 9.
[0036] The hybrid vehicle is provided with an ECU (electronic
control unit) 20 having an input/output device, a storage device
(ROM, RAM, or the like) for storing control programs and control
maps, a central processing unit (CPU), a timer counter, and so on
(which are not shown). The ECU 20 is a device which comprehensively
controls the engine 1, the generator 6, the motor 7 and so on based
on information from various sensors including the charge amount
sensor 15, and performs control on the process of charging the
battery 7 and the process of regenerating the purification capacity
of the DPNR 10.
[0037] In the DPNR 10, an SOx regenerating process in which the
temperature of the NOx catalyst bed is increased and a reducing
agent is supplied to the NOx catalyst is performed to eliminate SOx
poisoning, which is a phenomenon where SOx in the exhaust gas is
stored in the NOx catalyst and reduces the purification capacity of
the NOx catalyst. Also, when a large amount of collected
particulate matter (PM) is accumulated in the DPNR 10, the filter
is clogged and the back pressure in the exhaust gas is increased to
the extent that the engine performance is lowered. Therefore, a PM
regenerating process in which the temperature of the filter is
increased to remove the collected particulate matter by oxidation
is performed.
[0038] In either of the SOx regenerating process or the PM
regenerating process according to the first and second embodiments,
the energy of the exhaust gas is increased by increasing the engine
load and engine speed to increase the temperature of the exhaust
gas. Then, by introducing the high-temperature exhaust gas into the
DPNR 10, the temperature of the DPNR 10 is increased to a
temperature at which the PM regenerating process or the SOx
regenerating process may be performed.
[0039] Battery charge control in this hybrid vehicle is next
described. When the amount of charge in the battery 7 is small, the
ECU 20 performs charge control. That is, the engine load and engine
speed is increased to increase the amount of electricity to be
generated by the generator 6, and the generated electric power is
supplied to the battery.
[0040] The charging state/discharging state of electric power to
and from the battery 7 is controlled by controlling the amount of
electricity generated by the generator 6. That is, the ECU 20
controls the amount of electricity generated by controlling the
driving of the generator 6 by the engine 1, and controls the
charging state/discharging state of electric power to and from the
battery 7 by adjusting the relation between the amount of charge to
the battery 7 and the amount of discharge from the battery 7.
[0041] As described above, in this hybrid vehicle, the engine load
and engine speed is increased to perform a PM regenerating process,
an SOx regenerating process and a battery . charging process.
Because the operating conditions of the engine 1 are forcibly
changed when these processes are performed, the driveability or the
fuel efficiency of the vehicle may deteriorate if these processes
are frequently performed.
[0042] Therefore, in the first and second embodiments, the PM
regenerating process or the SOx regenerating process and the
battery charging process are performed as simultaneously as
possible to decrease the frequency of the control that increases
the engine load and engine speed.
[0043] FIG. 2 shows a flowchart of a first battery charging routine
1 in the first embodiment. The first battery charging routine 1 is
a program stored in the ROM of the ECU 20, and is executed at
predetermined intervals by the ECU 20 when the power switch of the
hybrid vehicle is ON.
[0044] When the first battery charging routine 1 is started, it is
first determined whether a request to charge the battery 7 has been
issued in step S101. Here, the presence or absence of a request to
charge the battery 7 is determined based on whether a battery
charge request flag is ON. The battery charge request flag is set
to ON when an output from the charge amount sensor 15 is read into
the ECU 20 and the amount of charge is equal to or less than, for
example, 50% of the maximum amount of charge (the value 50% as a
threshold is hereinafter referred to as "threshold charge amount").
If it is determined that a battery charge request has not been
issued here, the first battery charging routine 1 is then ended. If
it is determined that a battery charge request has been issued, the
first battery charging routine 1 proceeds to step S102.
[0045] In step S102, the battery charging process is started. More
specifically, in the battery charging process, the engine load and
engine speed are set to Q1 and N1, respectively.
[0046] Fixed values obtained experimentally in advance or values
corresponding to the output value from the charge amount sensor 15
read from a map may be used as the values Q1 and N1. When step S102
is completed, the routine proceeds to step S103.
[0047] In step S103, it is determined whether a request for PM
regeneration has been issued. Here, whether a request for PM
regeneration has been issued is determined based on whether a PM
regeneration request flag is ON. The PM regeneration request flag
may be set to ON when an output from a differential pressure sensor
(not shown) provided upstream and downstream of the DPNR 10 is read
into the ECU 20 and the amount of accumulated PM, which is
estimated from the differential pressure, is determined to be equal
to or greater than a threshold PM accumulation amount obtained
experimentally in advance or may be set to ON when the distance
that the vehicle traveled after the previous PM regenerating
process is counted and the amount of accumulated PM estimated from
the travel distance is determined to be equal to or greater than
the threshold PM accumulation amount.
[0048] If it is determined that a request for PM regeneration has
not been issued, the routine proceeds to step S106 because no PM
regenerating process is performed. If it is determined that a
request for PM regeneration has been issued, the routine proceeds
to step S104.
[0049] In step S104, the PM regenerating process is started. More
specifically, the engine load and engine speed may be changed to Q2
and N2, respectively. That is, when the engine load and engine
speed necessary to remove the PM in the DPNR 10 by oxidation are
greater than the engine load Q1 and the engine speed N1,
respectively, necessary to charge the battery 7, the engine load
and engine speed may be changed to those necessary to remove the PM
in the DPNR 10 by oxidation. When the engine load and engine speed
necessary to remove the PM in the DPNR 10 by oxidation are,
respectively, equal to or smaller than the engine load Q1 and the
engine speed N1 necessary to charge the battery 7, the engine load
and engine speed may be maintained at Q1 and N1, respectively. The
engine load Q2 and the engine speed N2 necessary to remove the PM
in the DPNR 10 by oxidation may be fixed values obtained
experimentally in advance, or values corresponding to the output
from the differential pressure sensor or the distance traveled
after the previous PM regenerating process may be read from a map.
When step S104 is completed, the routine proceeds to step S105.
[0050] In step S105, it is determined whether the PM regenerating
process has been completed. The PM regeneration may be determined
to be completed when the output value from the differential
pressure sensor is equal to or smaller than a PM regeneration
completing differential pressure obtained experimentally in advance
or when the duration of the PM regenerating process is equal to or
longer than a PM regeneration completing period obtained
experimentally in advance.
[0051] If it is determined that the PM regenerating process has
been completed in step S105, the routine proceeds to step S106. If
it is determined that the PM regenerating process has not been
completed yet, the routine returns to the upstream side of step
S104 and the PM regenerating process is continued.
[0052] In step S106, it is determined whether a request for SOx
regeneration has been issued. More specifically, it is determined
whether an SOx regeneration request flag is ON. The SOx
regeneration request flag may be set to ON when the amount of SOx
stored in the DPNR 10, which is estimated from an output value from
an NOx sensor (not shown) provided downstream of the DPNR 10,
becomes equal to or greater than a threshold SOx storage amount
obtained experimentally in advance or may be set to ON when the
amount of SOx estimated from the distance that the vehicle traveled
after the previous SOx regenerating process becomes equal to or
greater than the threshold SOx storage amount.
[0053] If it is determined that there is no request for SOx
regeneration in step S106, the routine proceeds to step S109. If it
is determined that there is a request for SOx regeneration, the
routine proceeds to step S107.
[0054] In step S107, the SOx regenerating process is started. More
specifically, after changing the engine load and engine speed to Q3
and N3, respectively, a rich spike control, in which a reducing
agent is supplied from a reducing agent adding device (not shown)
to the DPNR 10 in a spike manner, is executed. That is, the engine
load Q3 and the engine speed N3 necessary to increase the
temperature of the DPNR 10 to a temperature sufficiently high to
reduce and release the SOx stored in the DPNR 10 are greater than
the engine load Q1 and the engine speed N1 necessary to charge the
battery 7 as well as the engine load Q2 and the engine speed N2
necessary for the PM regenerating process, the engine load and
engine speed may be changed to Q3 and N3, respectively.
[0055] When the engine load Q3 and the engine speed N3 necessary to
increase the temperature of the DPNR 10 to a temperature
sufficiently high to reduce and release the SOx stored in the DPNR
10 are lower than the engine load and engine speed currently set,
the engine load and engine speed may be maintained at the current
values. The engine load Q3 and the engine speed N3 may be fixed
values obtained experimentally in advance, or values corresponding
to the output from the NOx sensor or the distance traveled after
the previous SOx regenerating process may be read from a map. When
step S107 is completed, the routine proceeds to step S108.
[0056] In step S108, it is determined whether the SOx regenerating
process has been completed. The SOx regenerating process may be
determined to be completed when the output value from the NOx
sensor is equal to or smaller than an SOx regeneration completing
concentration obtained experimentally in advance or when the
duration of the SOx regenerating process is equal to or longer than
a regeneration completing period obtained experimentally in
advance.
[0057] If it is determined that the SOx regenerating process has
been completed in step S108, the routine proceeds to step S109. If
it is determined that the SOx regeneration process has not been
completed yet in step S108, the routine returns to the upstream
side of step S107 and the SOx regenerating process is
continued.
[0058] Then, in step S109, it is determined whether the battery
charging process has been completed. The battery charging process
may be determined to have been completed when, for example, the
output value from the charge amount sensor 15 is 95% or higher of
full charge or when the duration of the battery charging process is
equal to or longer than a battery charge completing period obtained
experimentally in advance. If it is determined that the battery
charging process has not been completed yet in step S109, the
routine returns to the upstream side of step S102. If it is
determined that the battery charging process has been completed,
the first battery charging routine 1 is then ended.
[0059] As described above, in the first battery charging routine 1,
when a battery charging process is performed, the engine load and
engine speed are increased and the presence or absence of a request
for the PM regenerating process and a request for the SOx
regenerating process is determined. When there is a request for the
PM regenerating process or SOx regenerating process, the state in
which the engine load and engine speed have been increased is also
used for the process.
[0060] Therefore, the opportunities where the engine load and
engine speed is increased independently from the driver's intention
may be reduced as much as possible to reduce the opportunities for
deterioration of the driveability of the hybrid vehicle as much as
possible, and the fuel efficiency can be improved.
[0061] Next, a second battery charging routine 2, according to the
first embodiment is described. The second battery charging routine
2 is similar to the first battery charging routine 1 in that the
presence or absence of a request for the PM regenerating process
and a request for the SOx regenerating process is determined when a
battery charging process is performed, but differs in that a step
of decreasing the value of the threshold PM accumulation amount to
determine whether to issue a request for the PM regenerating
process and a step of decreasing the value of the threshold SOx
storage amount as a criterion to determine whether to output a
request for the SOx regenerating process are included before
determining the presence or absence of a request for the PM
regenerating process and before determining the presence or absence
of a request for the SOx regenerating process, respectively.
[0062] FIG. 3 shows a flowchart of a second battery charging
routine 2 according to the first embodiment. The second battery
charging routine 2 differs from the first battery charging routing
1 in that step S201 is inserted before step S103 and step S202 is
inserted before step S106. Here, only the differences between the
first and second battery charging routine 1 and 2, respectively,
are described.
[0063] In step S201, the threshold PM accumulation amount, used to
determine whether to issue a request for PM regeneration, is
decreased. For example, the threshold PM accumulation amount may be
decreased to 80% of the value used in the battery charging routine.
After decreasing the value of the threshold PM accumulation amount,
the routine proceeds to step S103 and it is determined whether
there is a request for PM regeneration.
[0064] In step S202, the threshold SOx storage amount, used to
determine whether to issue a request for SOx regeneration, is
decreased. For example, the threshold SOx storage amount may be
decreased to 80% of the value used in the battery charging routine.
After decreasing the value of the threshold SOx storage amount, the
routine proceeds to step S106 and it is determined whether there is
a request for SOx regeneration.
[0065] As described above, in the second battery charging routine
2, before determining the presence or absence of a request for PM
regeneration or a request for SOx regeneration, the condition to
determine whether to issue a request is relaxed. Thus, a state in
which a request for PM regeneration or a request for SOx
regeneration is more likely to be issued than in a normal state can
be established.
[0066] Therefore, the probability that the battery charging process
and the PM regenerating process or the SOx regenerating process can
be performed simultaneously is increased, and the driveability and
the fuel efficiency of the hybrid vehicle can be improved more
reliably.
[0067] In the above, when the ECU 20 performs steps S104, S105,
S107 and S108, it functions as the regenerating means according to
the present invention. When the ECU 20 performs steps S102 and
S109, it functions as the charging means according to the present
invention. Finally, when performing steps S102, S103 and S106, the
ECU 20 functions as the second multitasking means according to the
present invention.
[0068] While the threshold PM accumulation amount is used as a
criterion to determine whether to set the PM regeneration request
flag to ON and the threshold SOx storage amount is used as a
criterion to determine whether to set the SOx regeneration request
flag to ON in the above, the history of operating conditions of the
engine 1 may be used as an additional criterion. Here, either of
the threshold PM accumulation amount or the threshold SOx storage
amount may be regarded as a prescribed amount of accumulated matter
in the present invention. Also, any of the criteria including these
values and the history of operating conditions of the engine 1 may
be regarded as a second execution conditions in the present
invention.
[0069] A second embodiment of the present invention is next
described. In the second embodiment, the presence or absence of a
request for the battery charging process is determined during a PM
regenerating process in contrast to the first embodiment.
[0070] FIG. 4 shows a flowchart of a first PM regenerating routine
1 according to the second embodiment. When the first PM
regenerating routine 1 is started, it is first determined whether a
request for PM regeneration has been issued in step S301. Whether a
request for PM regeneration has been issued is determined based on
whether the PM regeneration request flag is ON, as in the first
embodiment. If it is determined that a request for PM regeneration
has not been issued, the first PM regenerating routine 1 ends. If
it is determined that a request for PM regeneration has been
issued, the routine proceeds to step S302.
[0071] In step S302, the PM regenerating process is started. More
specifically, the engine load and engine speed may be changed to Q2
and N2, respectively. This control is the same as the process in
step S104 in the first embodiment. When step S302 is completed, the
routine proceeds to step S303.
[0072] In step S303, it is determined whether a request to charge
the battery 7 has been issued. Here, the presence or absence of a
request to charge the battery 7 is determined based on whether a
battery charge request flag is ON, as in the first embodiment. If
it is determined that a battery charge request has not been issued
here, the routine proceeds to step S306. If it is determined that a
battery charge request has been issued, the routine proceeds to
step S304.
[0073] In step S304, the battery charging process is started. More
specifically, the engine load and engine speed are set to Q1 and
N1, respectively. As the values Q1 and N1, fixed values obtained
experimentally in advance may be used or values corresponding to
the output value from the charge amount sensor 15 may be read from
a map. When the values Q2 and N2 are greater than the values Q1 and
N1, respectively, the engine load and engine speed may be
maintained at Q2 and N2, respectively. When step S304 is completed,
the routine proceeds to step S305.
[0074] In step S305, it is determined whether the battery charging
process has been completed. The battery charging process may be
determined to have been completed when, for example, the output
value from the charge amount sensor 15 is 95% or higher of full
charge or when the duration of the battery charging process is
equal to or longer than a battery charge completing period obtained
experimentally in advance. If it is determined that the battery
charging process has not been completed yet here, the routine
returns to the upstream side of step S304 and the battery charging
process is continued. If it is determined that the battery charging
process has been completed, the routine proceeds to step S306.
[0075] In step S306, it is determined whether the PM regenerating
process has been completed. The PM regeneration may be determined
to have been completed when the output value from the differential
pressure sensor is equal to or smaller than a PM regeneration
completing differential pressure obtained experimentally in advance
or when the duration of the PM regenerating process is equal to or
longer than a PM regeneration completing period obtained
experimentally in advance.
[0076] If it is determined that the PM regenerating process has not
been completed yet in step S306, the routine returns to the
upstream side of step S302 and the PM regenerating process is
continued. If it is determined that the PM regenerating process has
been completed, the routine is then ended.
[0077] As described above, in this routine, the presence or absence
of a battery charge request is determined when a PM regenerating
process is performed in contrast to the first embodiment, and, if
there is a battery charge request, a battery charging process is
performed simultaneously with the PM regenerating process. The
driveability and fuel efficiency of the engine 1 can be also
improved by this control.
[0078] In the second embodiment, the threshold charge amount as a
criterion to determine whether to issue a battery charge request
may be also increased before determining the presence or absence of
a battery charge request.
[0079] FIG. 5 shows a flowchart of a second PM regenerating routine
2 in the above case. In this routine, step S401 is inserted before
step S303. In step S401, the threshold charge amount, used to
determine whether to issue a battery charge request (to set the
battery charge request flag to ON), is increased. For example, the
threshold charge amount is increased from 50% shown in the first
embodiment to 60%.
[0080] Then, a state in which a battery charge request is more
likely to be issued can be established, and the probability that a
PM regenerating process and a battery charging process can be
simultaneously performed is increased. As a result, the
driveability and the fuel efficiency of the engine 1 can be
improved more reliably.
[0081] In the second embodiment, when performing steps S302 and
S303, the ECU20 functions as the first multitasking means of the
present invention.
[0082] While the threshold charge amount is used as a criterion to
determine whether to set the battery charge request flag to ON in
the second embodiment, the rate of decrease in the amount of charge
in the battery 7 and the duration of use of the battery 7 itself
may be added as other criteria. Here, the threshold charge amount
may be regarded as a prescribed charge amount in the second
embodiment. Also, any of the criteria including the value, the rate
of decrease in the amount of charge in the battery 7 and the
duration of use of the battery 7 may be regarded as a first
execution condition in the present invention.
[0083] Also, in the above, it is needless to say that the control
device of the hybrid vehicle may use both the first and second
battery charging routines and the first and second PM regenerating
routines.
[0084] In the first and second embodiments, the control in which
the engine load and engine speed are increased to increase the
temperature of the DPNR 10 in a PM regenerating process or SOx
regenerating process is described as an example, the concept of the
present invention may be applied to the control in which a reducing
agent is added from upstream of the DPNR 10 to increase the
temperature of the DPNR 10 in a PM regenerating process or SOx
regenerating process. In this case, the engine load and engine
speed have been increased for the battery charging process and
therefore the temperature of exhaust gas from the engine 1 has been
increased to some extent, the amount of reducing agent to be added
from upstream of the DPNR 10 can be reduced. Improvement of the
fuel efficiency can be expected for this reason as well.
[0085] While the invention has been described with criterion to
example embodiments thereof, it is to be understood that the
invention is not limited to the described embodiments or
constructions. To the contrary, the invention is intended to cover
various modifications and equivalent arrangements. In addition,
while the various elements of the example embodiments are shown in
various combinations and configurations, other combinations and
configurations, including more, less or only a single element, are
also within the spirit and scope of the invention.
* * * * *