Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Electric vehicle
Reexamination Certificate
1998-11-24
2001-12-11
Louis-Jacques, Jacques H. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Electric vehicle
C701S054000, C701S110000, C180S065230, C180S065800
Reexamination Certificate
active
06330498
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control system for controlling a hybrid vehicle having an internal combustion engine and an electric motor as separate propulsion sources.
2. Description of the Related Art
There have heretofore been known hybrid vehicles each having an internal combustion engine and an electric motor as separate propulsion sources. One known control system for controlling the propulsion sources of such a hybrid vehicle is a control system mounted on a large-size bus as disclosed in Japanese laid-open patent publication No. 3-121928.
The disclosed control system, which controls a hybrid vehicle having a diesel engine and an electric motor, determines an assistive power to be generated by the electric motor based on the rotational speed NE of the diesel engine and the position of a control rack of a fuel supply pump. The control system controls the electric motor to generate an assistive power for the diesel engine when the diesel engine is subject to a high load range higher than a predetermined level. The diesel engine is thus operated only in a load range smaller than a full load range for the purpose of improving engine exhaust gases containing nitrogen oxides and black smoke. The control system primarily controls the electric motor to generate an assistive power when the large-size bus starts to move, posing a high load on the diesel engine. However, it is preferable for the electric motor to generate an assistive power depending on the propulsive force that is needed by the hybrid vehicle even when the hybrid vehicle is normally accelerated. Since the conventional control system does not pay much attention to the generation of an assistive power from the electric motor when the hybrid vehicle is further accelerated while the diesel engine is rotating at a high speed or the hybrid vehicle is running at a high speed, the conventional control system suffers drawbacks as described below.
When the hybrid vehicle is to be accelerated while it is running at a high speed, the driver tends to press the accelerator pedal deeply though it does not intend to accelerate the hybrid vehicle so rapidly. Therefore, the control system may control the electric motor to generate an assistive power even if such an assistive power generated by the electric motor is not in fact required. When this happens, a certain amount of stored electric energy is wasted by the electric motor, and it may be too large to energize the electric motor to generate a sufficient assistive power that may be necessary next time to accelerate the hybrid vehicle from a low speed. When the hybrid vehicle is running at a high speed or the diesel engine is rotating at a high speed, since the resistance to the running of the hybrid vehicle (running resistance) and the counterelectromotive force of the electric motor are large, a large amount of stored electric energy is needed to energize the electric motor to generate an assistive power.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a control system for controlling the electric motor on a hybrid vehicle to generate an assistive power depending on a manipulated variable from a drive power control means for the hybrid vehicle such that the assistive power generated by the electric motor is reduced when the hybrid vehicle is running at a high speed, for thereby saving electric energy stored for energizing the electric motor, and the electric motor generates a sufficient assistive power when the engine is to be effectively assisted thereby as when the hybrid vehicle is running at a low speed.
Another object of the present invention is to provide a control system for reducing the output power of an electric motor on a hybrid vehicle when the rotational speed of the engine on the hybrid vehicle or the speed of the hybrid vehicle exceeds a predetermined level.
Still another object of the present invention is to provide a control system for reducing the output power of the electric motor on a hybrid vehicle when a detected manipulated variable from a drive power control means for controlling the drive power of the hybrid vehicle is lower than a reference level established on the basis of the rotational speed of an engine on the hybrid vehicle or the speed of the hybrid vehicle.
Yet another object of the present invention is to provide a control system for increasing the output power of the engine on a hybrid vehicle in synchronism with a reduction in the output power of the electric motor on the hybrid vehicle when the engine is rotating in a high speed range or the hybrid vehicle is running in a high speed range.
According to the present invention, there is provided a control system for controlling a hybrid vehicle having an engine for rotating a drive axle, an electric motor for assisting the engine in rotating the drive axle, and electric energy storage means for supplying electric energy to the electric motor, comprising drive assistance control means for calculating an output power of the electric motor depending on an operating status of the hybrid vehicle and assisting the engine based on the calculated output power of the electric motor, and detecting means for detecting a rotational speed of the engine or a speed of the hybrid vehicle, the drive assistance control means comprising means for reducing the output power of the electric motor when the detected rotational speed of the engine or the detected speed of the hybrid vehicle exceeds a predetermined value.
With the above arrangement, when the detected rotational speed of the engine or the detected speed of the hybrid vehicle exceeds the predetermined value, the output power of the electric motor is reduced, and hence the assistive power generated by the electric motor is reduced. Therefore, the electric energy stored for energizing the electric motor is saved when the engine outputs a high power as when the speed of the hybrid vehicle or the rotational speed of the engine is high. The electric motor is controlled to generate a sufficient assistive power when the engine is to be effectively assisted thereby as when the hybrid vehicle is running at a low speed.
According to the present invention, there is also provided a control system for controlling a hybrid vehicle having an engine for rotating a drive axle, an electric motor for assisting the engine in rotating the drive axle, electric energy storage means for supplying electric energy to the electric motor, and drive power control means for controlling a demand drive power of the hybrid vehicle, comprising drive assistance control means for calculating an output power of the electric motor depending on the demand drive power of the hybrid vehicle and assisting the engine based on the calculated output power of the electric motor, and manipulated variable detecting means for detecting a manipulated variable from the drive power control means, the drive assistance control means comprising means for reducing the output power of the electric motor when the detected manipulated variable from the drive power control means is smaller than a predetermined reference value.
With the above arrangement, when the detected manipulated variable from the drive power control means is smaller than the predetermined reference value, the output power of the electric motor is reduced. The assistive power generated by the electric motor is reduced, thus saving electric energy stored for energizing the electric motor, when there is no or little need to assist the engine. If the reference value is established so as to increase as the rotational speed of the engine or the speed of the hybrid vehicle increases, then since it is more likely for the output power of the electric motor to be reduced when the engine outputs a high power, the electric energy stored for energizing the electric motor is saved when the engine outputs a high power. The electric motor is controlled to generate a sufficient assistive power when the engine is to be effectively assisted thereby as when the h
Ishikawa Motoshi
Oshima Yoshikazu
Tamagawa Yutaka
Yano Toru
Arent Fox Kintner & Plotkin & Kahn, PLLC
Broadhead Brian J
Honda Giken Kogyo Kabushiki Kaisha
Louis-Jacques Jacques H.
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