Internal-combustion engines – Engine speed regulator – Idle speed control
Patent
1984-02-22
1986-11-04
Cox, Ronald B.
Internal-combustion engines
Engine speed regulator
Idle speed control
F02D 1110
Patent
active
046205179
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an apparatus for controlling the rotational speed of an engine through intermittent control of an actuator serving to adjust the engine speed.
BACKGROUND ART
In the automobile engine, it is generally customary to lower the idling speed thereof for attaining an improved fuel economy as well as reducing the amount of exhaust gas. However, considering the variation in engine capabilities and the subsequent secular change induced therein, a certain limit is existent in lowering the idling speed. Under such circumstances, it is the latest trend to employ an electronic control apparatus which is capable of achieving accurate and stable control of the idling speed continuously for a long time.
FIG. 1 is a block diagram of an exemplary conventional apparatus used for control of an idling speed by changing the stopper position of a throttle valve with employment of a DC motor. The apparatus shown comprises an ignition coil 1, an ignition coil controller 2, a period measuring circuit 3, an actual speed computing circuit 4 (second unit), a desired speed computing circuit 5 (first unit), a load switch 51 for an air conditioner or the like, a cooling water temperature sensor 52, a difference detecting circuit 6 (third unit), a control pulse width computing circuit 7 (fourth unit), a pulse width counter 8, a control period counter 9, a control signal generating circuit 10 (fifth, unit), a driving circuit 11 (sixth unit), a throttle valve actuator 12, a throttle valve 13, and an accelerator pedal 14. The throttle valve actuator 12 comprises a DC motor 121, a reduction mechanism 122 for converting the rotary motion of the DC motor 121 into a linear motion, an idle switch 123 for detecting the fully closed position of the accelerator pedal 14, a throttle stopper 124 moved linearly by the reduction mechanism 122, and a cam mechanism 125 interlocked with the throttle valve 13.
In the conventional apparatus mentioned above, the following operation is performed. Period measuring circuit 3 is connected to ignition coil 1 so as to measure the time interval between ignition signals. Actual speed computing circuit 4 converts the output of period measuring circuit 3, which represents the time interval between ignition signals, into a speed signal of a weight corresponding to the actual rotational speed. Desired speed computing circuit 5 computes a desired idling speed and feeds the result to difference detecting circuit 6. Then the circuit 6 compares the output of actual speed computing circuit 4 with the output of desired speed computing circuit 5 and feeds the difference therebetween as a rotational speed difference signal to control pulse width computing circuit 7 while outputting a signal, which represents the numerical relationship between the output values of computing circuits 4 and 5, to both control pulse width computing circuit 7 and control signal generating circuit 10. Control pulse width computing circuit 7 computes an optimal time for driving DC motor 121 in accordance with the aforesaid two signals and feeds the result to pulse width counter 8. FIG. 2 graphically shows the relationship between the rotational speed difference signal and the DC motor driving time, wherein the speed difference is plotted along the abscissa while the driving time is plotted along the ordinate. Since the driving time is zero within a range where the speed difference is less than a dead zone speed Nd, DC motor 121 is not driven so that the position of throttle stopper 124 remains unchanged. The right side from the zero point of the speed difference corresponds to a range where the actual engine speed is lower than the desired idling speed, representing the relationship between the speed difference and the driving time in the case of opening throttle valve 13 by rotating DC motor 121 in its forward direction and shifting cam mechanism 125 via throttle stopper 124. To the contrary, the left side from the zero point of the speed difference corresponds to a range where the actual engine spee
REFERENCES:
patent: 4391244 (1983-07-01), Kobashi
patent: 4453518 (1984-06-01), Nakamura
patent: 4484552 (1984-11-01), Kobayashi
patent: 4484554 (1984-11-01), Nakajima
patent: 4524738 (1985-06-01), Chastagner
patent: 4524739 (1985-06-01), Kashiwaya
Ishii Mitsuaki
Kakinuma Hideo
Miyazaki Masaaki
Nakamura Noboru
Cox Ronald B.
Mitsubishi Denki & Kabushiki Kaisha
Mitsubishi Jidosha Kogyo Kabushiki Kaisha
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