This invention relates to a motor control apparatus combined with an engine, particularly to a motor control apparatus combined with an engine, in which the engine rotational speed in the idling state is controlled to be constant, so that the stillness or quietness of the noise from the engine is improved.
Some motor vehicles are of a type commonly called a hybrid vehicle having an internal combustion engine and an electric motor (referred to as motor throughout the specification) combined with the engine. The engine and motor are disposed in the vehicle as the power sources of a propulsion system. The hybrid vehicle further includes an engine control means for controlling a running state of the engine and a motor control means for controlling an operating state of the motor. The engine controller and the motor controller detect respective operating states of the engine and the motor when the vehicle is traveling, and then exchange such detected data regarding the running states. As a result, the respective operating states of the engine and the motor are controlled in association with each other. Such a control system attains a high level of required performance (such as fuel efficiency, lower values of detrimental components in exhaust gases, and power performance).
One such example of a control apparatus for a vehicle is disclosed in published Japanese Patent Application Laid-Open No. 5-106474. A power train consists of a tandem connection of an engine with switchable output characteristics and an automatic transmission. Power from a variable output characteristic engine is speed-changed by the automatic transmission. A stall start detecting means detects a stall start in the power train and controls a characteristic restricting means that prohibits the selection of an output characteristic enlarging torque. The engine does not output increased torque at the time of the stall start and degradation of parts in a driving system can be eliminated.
In published Japanese Patent Application Laid-Open No. 10-136508, the power generating control apparatus for a vehicle, including a control apparatus of an AC generator for a vehicle having both a magnetization control circuit for a magnetic field coil and a three aspect full-wave rectification diode, has the following means:
(a) a magnetizing current ratio control means varying a magnetizing current ratio of a magnetization control circuit in a charge voltage of the capacitor charging by a signal from a pulse generating means;
(b) an electric current increase detecting means for detecting an increase of the electric current when one was conductive at least at a minus (xe2x88x92) side of a three aspect full-wave rectification diode; and
(c) magnetizing current ratio increase limit means for reducing an increasing rate of the magnetizing current ratio of the magnetization control circuit, by varying an electric current of the capacitor in the magnetizing current ratio control means when an increase of the electric current is detected.
In a power generating control apparatus for a vehicle, this apparatus detects a sudden increase of electricity load surely and directly, and quickly reduces an increase in engine torque, and controls the magnetizing current ratio of a magnetic field coil according to an engine rotational speed.
Published Japanese Patent Application Laid-Open No. 6-343300 discloses a power generating control apparatus for an internal combustion engine that includes an operation signal output means to output an operation signal in the operation of an electricity load using the output of a power generating unit by an engine drive. A power supply for the output of the power generating unit is charged. A control means stabilizes an engine idling speed by increasing a fuel supply to the engine when an operation signal is output from the operation signal output means during idling of an engine. When an operation signal is output from the operation signal output means during idling of an engine, the control means has an output voltage control function controlling so as to gradually return to the original output voltage in a predetermined time after being controlled, so as to vary a magnetic field electric current of the power generating unit and so as to reduce an output voltage of the power generating unit. By this control means, the stabilization of engine idling speed is planned while restraining fuel consumption in the electricity load operation at engine idling, and an improvement of fuel efficiency is expected.
Also, published Japanese Patent Application Laid-Open No. 10-23604 discloses a control means of a hybrid vehicle that has an engine running by combustion of fuel and an electric motor operating with electric energy as power source for vehicle traveling, and disposes an engine stall determining means to judge the possibility of engine stall during a running operation of the engine. An engine stall prevention motor control means reduces a load of an engine by an electric motor when it is judged by the engine stall determining means that the engine may stall, for preventing the engine stall beforehand.
In published Japanese Patent Application Laid-Open No. 11-41992, a mixed-supply system by an engine driving generator and a battery, using an engine generating unit as a supporting power supply, controls so as to operate a loaded motor or something loaded and so as to do a supporting charge to a battery of a stationary type or laying-on-vehicle type, and so as to control by a hand-operated control unit, in order to maintain a battery in a good accumulation of electricity state. And, the system does a measuring of the battery by sensing an accumulation of electrical charge with an electricity state measuring device controlled by a control mode set inside of a center control unit, and compares with its measured signal value a predetermined value. Moreover, the relative control running to an engine drive power generating unit, improves an electricity supply ability for a load condition, and hereby, an inconvenience of charge may be cancelled, and a function of system running may be improved.
In a usual motor control means combined with an engine, as mentioned in published Japanese Patent Application Laid-Open No. 10-023604, the control means has the engine stall determining means judging the possibility of engine stall, hereby, preventing the engine stall by using a motor generator (electric motor) when it is judged by the engine stall determining means that the engine may stall. In other words, the above control means controls the motor generator (an electric motor) so that an engine stall is not caused.
Here, the control means in above-mentioned published Japanese Patent Application Laid-Open No. 10-023604, has no stabilization control for engine rotational speed in idling, and has not considered vibration and noise in an idling state. As a result, there is the anxiety that quiet vehicle operation is lost in the control and this characteristic is disadvantageous in practical use.
An idling state is controlled fundamentally by an idle speed controller (ISC), but the ISC is not always enough because the control sensitivity and the control speed are influenced by pneumatic speed, therefore, a so-called idle stabilization to hold an engine rotational speed in an idling state at a predetermined constant value is necessary.
In order to obviate the above inconvenience, the present invention provides a motor control apparatus combined with an engine, the engine and an electrical motor having both driving and power-generation functions, and having a determining means for determining an idling state of the engine, comprising an engine rotational speed-detecting means for detecting an engine rotational speed; and, a control means controlling so as to return the engine rotational speed to the predetermined engine rotational speed, varying the engine rotational speed by changing an operating state of the motor, when the engine rotational speed output as a detection signal from the engine rotational speed-detecting means varies from a predetermined engine rotational speed set beforehand for the idling state of the engine.
According to the present invention as previously described, in case of the idling state of an engine, when the engine rotational speed measured by a detection signal from the engine rotational speed detecting means or an engine rotational speed sensor varies from a predetermined engine rotational speed set beforehand, then the control means controls so as to change the engine rotational speed by changing a running state of the motor, and the engine rotational speed is returned to the predetermined engine rotational speed. Hereby, the engine rotational speed in the idling state is converged to the predetermined engine rotational speed, and becomes constant in order to stabilize engine idling.