Prime-mover dynamo plants – Electric control – Engine control
Reexamination Certificate
2000-08-07
2002-03-26
Ponomarenko, Nicholas (Department: 2834)
Prime-mover dynamo plants
Electric control
Engine control
C180S065230
Reexamination Certificate
active
06362536
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus and method for controlling power generation in a hybrid vehicle which comprises an engine and an electric motor as a power source for driving the vehicle. In particular, the present invention relates to a technique for controlling power generation amount when the engine is idling.
2. Description of Related Art
Conventionally, hybrid vehicles which carry motors as power sources for driving the vehicles in addition to engines are known. Hybrid vehicles are divided into series hybrid vehicles and parallel hybrid vehicles. In the series hybrid vehicles, the engine drives a generator whose electric power output is used to drive the motor, which in turn drives the wheels. In this case, because the output of the engine is not mechanically connected to the driving wheels, the engine can be constantly driven within an engine-speed range of a high fuel mileage and a low emissions level. Therefore, the series hybrid vehicles can achieve lower fuel consumption and lower emissions levels than conventional engine vehicles.
In contrast, in the parallel hybrid vehicles, as is disclosed in Japanese Unexamined Patent Application, First Publication No. Hei 7-123509, a motor is mechanically coupled to an engine so as to assist the rotation of the drive shaft of the engine. The motor can also act as a power generator to generate electrical power, and the generated electrical energy is stored in a battery. The electrical energy charged in the battery can be supplied to electrical equipment and so on in the vehicle.
In this case, although the output of the engine is mechanically connected to the driving wheels, drive loads on the engine can be reduced. Therefore, the parallel hybrid vehicles can also achieve lower fuel consumption and lower emissions levels than conventional engine vehicles.
The parallel hybrid vehicles can be divided into several types. One is a type in which a motor is connected to an output shaft of an engine so that the motor can assist the output of the engine, and such as when the vehicle decelerates, the motor acts as a generator to charge a battery, etc. Another is a type in which both or either of a motor and an engine can generate driving force, and a generator is independently provided.
These hybrid vehicles perform various controls, for example, when the vehicle accelerates, the motor assists the output of the engine, and when the vehicle decelerates, the motor generates electric power by deceleration regeneration to charge a battery, etc. Therefore, it is possible to constantly maintain electrical energy (the remaining battery charge) in the battery and to respond to the demands by the driver of the vehicle. For example, Japanese Unexamined Patent Application, First Publication No. Hei 7-123509 discloses such a control technique.
In the above-described hybrid vehicles, when power assistance by the motor is not necessary, the motor regenerates electric power to charge a battery. This regeneration of electric power is performed not only when the vehicle decelerates but also when the engine is idling. That is, even when the engine is idling, the motor is rotated by the idling: engine acting as a generator.
However, when the engine is idling, should the total torque load of the load for the power generation by the motor, the load generated by a creep state of an automatic transmission system, and the load for activating an air conditioner, etc., be greater than the torque generated by the engine, there arises a problem that the engine will stall. In particular, when the hybrid vehicle is at high altitudes, this problem occurs more easily because the intake pressure of the engine is lower. If the idling speed of the engine is increased in order to prevent the engine from stalling, there arises another problem that the fuel consumption of the engine will undesirably increase.
Moreover, when starting the vehicle from the idling state, the hybrid vehicle controls the drive motor by automatically selecting one mode from an assistance mode in which the motor assists the output of the engine in accordance with demands, and a non-assistance mode in which the vehicle runs only by the driving power from the engine while charging a battery by the motor. For example, when a relatively large torque is required at the time of starting the vehicle, the assistance mode is selected, and when large torque is not required, the non-assistance mode is selected. Accordingly, depending on the conditions, the motor performs assistance of the driving power.
However, in the case where the non-assistance mode is selected when starting the vehicle, the engine drives the motor to generate electric power, and the generated electric power is charged in the battery. Therefore, the load for driving the motor (that is, power generation torque) is applied to the engine in addition to the torque for driving the vehicle, and the problem arises that smoothness at the time of starting the vehicle will be degraded.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an apparatus for controlling the power generation torque applied to an engine by a motor in accordance with a state of the hybrid vehicle.
In order to achieve the above object, a power generation control apparatus according to the first aspect of the present invention comprises: a detection device which detects a state of the hybrid vehicle in which a torque load to be applied to an engine of the hybrid vehicle should be decreased; and a generation amount control device which decreases the generation amount to be generated by a motor when the state of the hybrid vehicle is detected.
A hybrid vehicle according to another aspect of the present invention comprises: an engine which outputs a driving force for the hybrid vehicle; a motor which outputs an assistant driving force so as to assist the driving force of the engine; a power storage unit which supplies electric power to the motor when the assistant driving force is necessary, and which stores electric power generated by the motor when the assistant driving force is not necessary; and a power generation control apparatus which controls the power generation by the motor. The power generation control apparatus comprises: a detection device which detects a state of the hybrid vehicle in which a torque load to be applied to an engine of the hybrid vehicle should be decreased; and a generation amount control device which decreases the generation amount to be generated by a motor when the state of the hybrid vehicle is detected.
A power generation control method according to another aspect of the present invention comprises: a first step of detecting a state of the hybrid vehicle in which a torque load to be applied to an engine of the hybrid vehicle should be decreased; and a second step of decreasing the generation amount to be generated by a motor when the state of the hybrid vehicle is detected.
According to these aspects, a state of the hybrid vehicle in which a torque load to be applied to an engine of the hybrid vehicle should be decreased is detected, and the generation amount to be generated by a motor is decreased. Therefore, engine stall can be prevented and a smooth start of the vehicle is possible.
The another object of the present invention is to provide an apparatus for controlling the power generation torque applied to an engine by a motor in accordance with a necessary load when in an idling state.
In order to achieve the above object, a power generation control apparatus according to the first aspect of the present invention comprises: a load torque calculation device which calculates load torque to be applied to an engine of the hybrid vehicle for generating electrical power used in the hybrid vehicle when the engine is idling; a generable torque calculation device which calculates torque generable by the engine when the engine is idling; and a power generation load torque determination device which determines a limiting value of a power generation load torque to
Izumiura Atsushi
Kitajima Shinichi
Kiyomiya Takashi
Kuroda Shigetaka
Matsubara Atsushi
Armstrong Westerman & Hattori, LLP
Ponomarenko Nicholas
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