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Valve timing control system for internal combustion engine

  • US 6,397,803 B1
  • Filed: 08/15/2001
  • Issued: 06/04/2002
  • Est. Priority Date: 02/22/2001
  • Status: Expired due to Fees
First Claim
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1. A valve timing control system for an internal combustion engine, comprising:

  • sensor means for detecting operating states of an internal combustion engine;

    an intake valve driving cam shaft and an exhaust valve driving cam shaft for driving intake and exhaust valves, respectively, of said internal combustion engine in synchronism with rotation of a crank shaft of said engine;

    actuator means operatively connected to at least one of said intake valve driving cam shaft and said exhaust valve driving cam shaft for changing open/close timings of the relevant valve(s);

    actual valve timing detecting means for detecting an actual valve timing of at least one of said intake and exhaust valves;

    oil supply means for supplying a hydraulic pressure for driving said actuator means;

    a locking mechanism for retaining said actuator means at a lock-up position within a driving range within which said actuator means can be driven;

    an unlocking mechanism for releasing said locking mechanism in response to a predetermined hydraulic pressure supplied from said oil supply means; and

    control means for controlling the hydraulic pressure supplied from said oil supply means to said actuator means in dependence on said operating states of said internal combustion engine to thereby change a relative phase of said cam shaft relative to said crank shaft;

    said control means including;

    power supply interruption detecting means for detecting a time point when electric power supply is interrupted upon stoppage of said engine;

    desired valve timing setting means for setting a desired valve timing on the basis of said engine operation state; and

    actual valve timing control means for driving said actuator means so that said actual valve timing coincides with said desired valve timing, wherein said actual valve timing control means is designed to control said oil supply means over a predetermined time period extending from said power supply interruption time point in response to a result of detection of said power supply interruption detecting means for thereby allowing said actuator means to be retained at said lock-up position.

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