| 摘要 |
A fuel shutoff device adapted for incorporation into an automobile fuel supply system as to shut off the fuel supply during deceleration thereby reducing the amount of carbon monoxide and hydrocarbons emitted in exhaust. A throttle valve position detector is operatively associated with a throttle valve so as to produce a voltage signal corresponding to the position of the throttle valve. The voltage signal is applied to a fuel shutoff signal generator which generates a fuel shutoff signal when the time derivative of the voltage signal exceeds a predetermined value. The fuel shutoff signal is applied to a shutoff valve controller which is actuated to close a shutoff valve when the fuel shutoff signal is applied to the controller. The fuel shutoff signal is also applied to a fuel shutoff controller which de-energizes an injection pulse amplifying circuit when the fuel shutoff signal is applied to the controller. The present fuel shutoff device further includes a throttle valve switch which is adapted to be closed when the throttle valve is moved to its fully closed position. The throttle valve switch is connected to the shutoff valve controller. An engine driven triggering device which generates a signal indicating engine speed also is connected to the shutoff valve controller. Operation of the shutoff valve controller is such that with the throttle valve switch closed, when the engine speed rises to a first predetermined level, for example, 2000 rpm, the controller operates in such a manner as to close the shutoff valve. Further, with the throttle valve switch closed, when the engine speed decreases to a second predetermined level, for example, 1000 rpm, the shutoff valve is reopened by the controller. Since, in the present fuel shutoff device, the fuel supply to the cylinders is shut off during deceleration before the throttle valve is reached to its fully closed position, the amount of carbon monoxide and hydrocarbon exhaust is small in comparison with an automobile employing a conventional fuel shutoff device.
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