Motor vehicles – Power – Electric
Reexamination Certificate
2000-09-20
2004-03-09
Johnson, Brian L. (Department: 3618)
Motor vehicles
Power
Electric
C180S065100, C701S022000
Reexamination Certificate
active
06702052
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control apparatus for a hybrid vehicle, and particularly relates to a control apparatus for hybrid vehicles, which is capable of recovering the charge-discharge balance by activating the motor during the travel when the charge-discharge balance of the battery device shifts to an over-discharge state.
2. Background Art
Hybrid vehicles provided with a motor in addition to an engine are conventionally known. There are two types of hybrid vehicles: series hybrid vehicles and parallel hybrid vehicles. Series hybrid vehicles are driven by a motor which is driven by a generator driven by the engine.
Since the motor is not connected mechanically to the engine, the engine can be driven at an approximately constant rotation speed within an speed region wherein the engine can be driven at a lower fuel consumption rate and lower emission rate than the case of a conventional engine.
In contrast, in parallel hybrid vehicles, a motor directly connected to the engine assists the engine in rotating the drive shaft, and the motor is used as a generator for charging electric energy into a battery device, and the electric energy generated by the motor is used for a variety of electric equipment in the hybrid vehicle.
Thus, in parallel hybrid vehicles, since the driving load of the engine can be reduced, the fuel consumption rate and the emission rate can be improved.
There are several types of the above-described parallel hybrid vehicle, one is a type in which the motor for assisting the output of the engine is directly connected to the engine axis, and the motor functions as a generator for charging the battery when the hybrid vehicle decelerates, and the other one is a type in which both or either one of the engine and the motor can generates the driving force and a generator is additionally provided.
In hybrid vehicles such as those described above, the demands of the driver can be satisfied by preserving the electric energy of the battery (hereinafter, called “state of charge”, that is “remaining battery charge”) by carrying out a variety of controls so that the motor assists the engine at the time of acceleration, and the motor charges the battery by deceleration regeneration at the time of deceleration. For example, since a large amount of deceleration regeneration can be obtained after high speed travel, a part of the energy drawn from the battery can be recovered at the time of deceleration. That is, after climbing the uphill, the battery can be charged while travelling downhill (this technique is disclosed in Japanese Unexamined Patent Application, First Publication No. Hei 7-123509).
However, in conventional hybrid vehicles, when driven the hybrid vehicle without sufficient deceleration acceleration, the state of charge gradually decreases while driving the vehicle. Therefore, the problem arises that, when it is necessary to drive the car uphill, and subsequently drive on a flat road, the battery charge consumed at the time of driving the uphill can not be restored because no downhill regeneration is provided.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a control apparatus for a hybrid vehicle, capable of charging the battery device when the driving conditions are such that the state of charge is decreasing rather than increasing, and when the state of charge has decreased by a predetermined amount from the initially read value.
According to the first aspect, a control apparatus for a hybrid vehicle is provided which comprises: an engine for outputting a driving force of the vehicle (for example, the engine E in the embodiment); a motor (for example, the motor M in the embodiment) for generating an auxiliary driving force for assisting the output of the engine; a battery device (for example, the battery
3
in the embodiment) for supplying electric power to the motor and for storing regenerative energy obtained by a regenerative operation of the motor at the time of supplying electric power to the motor during deceleration of the vehicle; an assist determination device (for example, step S
005
in the embodiment) for determining whether it is necessary for the motor to assist the engine output in response to the driving conditions of the vehicle; an assist amount (for example, the final assist command value ASTPERF in the embodiment) determination device (for example, steps S
209
, S
211
, S
216
in the embodiment) for determining the assist amount of the engine output by the motor in response to the engine driving condition when the assist of the engine output is determined by the assist determination device; an assist control device for assisting the output of the engine by the motor based on the assist amount determined by the assist amount determination device; wherein the control apparatus of the hybrid vehicle comprises: a travel start detecting device (for example, step S
050
in the embodiment) for detecting the travel start of the vehicle; a state of charge (for example, SOC in the embodiment) detecting device (for example, the battery ECU
31
in the embodiment) for detecting the state of charge of the battery device; a discharge depth detecting device for detecting a discharge amount of the present state of charge (for example, the discharge depth DOD in step S
063
in the embodiment) by comparison with the initial state of charge (for example, the initial value of the state of charge SOCINT in step S
057
in the embodiment) detected at the time of starting the travel; a lower limit threshold value setting device (for example, step S
060
in the embodiment) for setting the lower limit threshold value (for example, the lower limit threshold value SOCLMTL in step S
060
in the embodiment) of the discharge amount based on the initial state of charge; an upper limit threshold value setting device (for example, step S
061
in the embodiment) for setting the upper limit threshold value (for example, the upper limit threshold value SOCLMTH in step S
061
in the embodiment) of the discharge amount based on the initial state of charge; a mode setting device (for example, step S
054
in the embodiment) for changing the control mode of the motor when the state of charge of the battery device is reduced to the lower limit threshold value; and a mode setting release device (for example, step S
062
in the embodiment) for releasing the setting of the motor control mode set by the mode setting device when the state of charge of the battery device reaches the upper limit threshold value; a determination threshold correction device (for example, step S
103
provided with step S
152
, step S
111
provided with step S
162
, step S
123
provided with step S
172
in the embodiment) for correcting the engine output determination threshold value (for example, the throttle assist trigger threshold value MAST, the suction pipe assist trigger threshold value MASTST, and the suction pipe assist trigger threshold value MASTTH in the embodiment) used as a standard for determination by the assist determination device in response to the discharge depth detected by the discharge depth detecting device when the motor control mode is changed by the mode setting device.
According to the above-described constitution, in the case of driving the hybrid vehicle by repeating sudden acceleration and sudden deceleration or in the case of driving climbing uphill and driving on a flat road subsequently without restoring the state of charge of the battery by the regeneration, the state of charge of the battery can be restored when the state of charge is decreasing and when the state of charge has decreased by a predetermined amount compared to the initial state of charge at the time of starting travel.
In addition, in the case of restoring the state of charge of the battery, a reduction in the state of charge of the battery can be recovered by reducing the frequency of the motor assist by raising the determination threshold value by the determination threshold value correction device depen
Izumiura Atsushi
Kitajima Shinichi
Kuroda Shigetaka
Nakamoto Yasuo
Nakaune Kan
Honda Giken Kogyo Kabushiki Kaisha
Johnson Brian L.
Klebe G B
Westerman Hattori Daniels & Adrian LLP
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