Motor vehicles – Power – Electric
Reexamination Certificate
2000-07-26
2001-09-18
Hess, Douglas (Department: 2167)
Motor vehicles
Power
Electric
C180S065310, C701S110000
Reexamination Certificate
active
06290012
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control device for a hybrid vehicle which is propelled by drive from an engine and a motor. In particular the invention relates to a control device for a hybrid vehicle for performing control of the driving force in the case where the output from the engine is rapidly increased from a situation where there is no assistance from the motor such as at the time of vehicle deceleration.
2. Description of the Related Art
Heretofore, there is known a hybrid vehicle incorporating a motor in addition to an engine as a drive source for vehicle propulsion. For one type of such hybrid vehicle, there is a parallel hybrid vehicle where the motor is used as an auxiliary drive source for assisting the output from the engine. With this parallel hybrid vehicle, for example, at the time of acceleration, the output from the engine is assisted by means of the motor, while at the time of deceleration, charging to a battery is performed by deceleration regeneration of the motor. Thus, with the parallel hybrid vehicle, various control is carried out, so that the residual capacity (electrical energy) of the battery can be maintained while satisfying the requirements of the driver. Such a parallel hybrid vehicle is disclosed, for example, in Japanese Patent Application, First Publication No. Hei 7-123509.
According to the control device for the abovementioned conventional hybrid vehicle, assistance (auxiliary drive) by the motor is provided during acceleration of the hybrid vehicle. However, in the case where, for example, after a condition where fuel supply to the engine has been stopped such as at the time of vehicle deceleration, fuel supply is suddenly reopened to move to acceleration, the driving force suddenly increases following the increase in output from the engine. Therefore, there is the problem of a sudden change occurring in the driving conditions of the hybrid vehicle. In order to address this problem, there is known a method where a sudden increase in driving force is suppressed by, for example, retarding the ignition timing of the engine, or by gradually increasing the throttle opening with the throttle actuator rather than following the movement of the throttle pedal, even in the case where the driver rapidly presses on the throttle pedal. However, with such a method where only the engine is controlled to suppress a rapid increase in the driving force, there is a problem of a deterioration in fuel consumption.
SUMMARY OF THE INVENTION
The present invention takes into consideration the above situation, with the object of providing a control device for a hybrid vehicle, which can suppress a rapid increase in driving force to maintain smooth travelling in the case where the output from the engine is increased in a situation where there is no assistance from the motor.
To achieve this object, a control device for a hybrid vehicle according to the present invention comprises characteristic devices. That is, the hybrid vehicle includes an engine for outputting a propulsion force for a vehicle, a motor for assisting the output from the engine, and a storage unit for storing generated energy when the motor is used as a generator under the output from the engine and regenerated energy obtained from regenerative braking of the motor at the time of vehicle deceleration. Moreover, the control device comprises an engine output detection device for detecting a change in output from the engine, and a motor control device for, in the case where an increase in output from the engine is detected at the time of vehicle travelling when the motor is not assisting the output from the engine, simultaneous with the increase in output, converting the increase amount in output into the generated energy using the motor.
According to the control device for a hybrid vehicle of the above construction, in the case where an increase in output from the engine is detected when the vehicle is travelling without the motor assisting the output from the engine such as for example at the time of vehicle deceleration, or at the time of cruise mode where the hybrid vehicle is travelling by the drive force of the engine without the motor driving, then simultaneous with this increase in output, the motor is regeneratively braked so that temporarily the increase amount in output is converted to generated energy. As a result, a sudden increase in drive force can be prevented, and the occurrence of a sudden change in the travelling conditions for the hybrid vehicle can be prevented. Furthermore, since the increase amount in the output is converted into generated energy, the storage unit can be charged by this, and a loss in energy due to the increase in drive force being suppressed can be prevented.
Here, simultaneous with the sudden increase in output from the engine, the motor is regeneratively braked so that temporarily the increase amount in output from the engine is converted into generated energy. After this, the amount out of the increase amount in output from the engine, which is converted into generated energy, may be gradually reduced, so that the amount of generated energy becomes zero at a point in time when motor assistance commences. In this way, the drive force can be smoothly increased, and the travelling feeling at the time of acceleration can be improved. Moreover, a lower limit threshold value for the amount of generated energy in this case may be set, and the decreasing of the amount of generated energy may be stopped at a point in time when this lower threshold value is reached. In this way, in the case where the amount out of the increase amount of the output from the engine, which is converted to generated energy, is gradually decreased in order to gradually transmit the increase amount in output from the engine as a drive force, due to the set lower limit threshold value, operation can be selectively moved to either of for example a condition where a comparatively small amount of generated energy is being produced such as a vehicle deceleration condition or in cruise mode, or a condition for an acceleration mode where the drive force of the engine is being assisted by the drive force from the motor.
REFERENCES:
patent: 5806617 (1998-09-01), Yamaguchi
patent: 5839533 (1998-11-01), Mikami et al.
patent: 5898282 (1999-04-01), Drozdz et al.
patent: 6123163 (2000-09-01), Otsu et al.
patent: 6140780 (2000-10-01), Oshima et al.
patent: 07-123509 (1995-05-01), None
Iwamoto Takashi
Kitajima Shinichi
Kiyomiya Takashi
Matsubara Atsushi
Sawamura Kazutomo
Armstrong Westerman Hattori McLeland & Naughton LLP
Gort Elaine
Hess Douglas
Honda Giken Kogyo Kabushiki Kaisha
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