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Malfunction detection apparatus for detecting malfunction in evaporated fuel purge system

  • US 5,158,054 A
  • Filed: 10/10/1991
  • Issued: 10/27/1992
  • Est. Priority Date: 10/15/1990
  • Status: Expired due to Term
First Claim
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1. An evaporated fuel purge system for use in an internal combustion engine, comprising:

  • a fuel tank in which fuel is evaporated into a fuel vapor;

    a canister containing an adsorbent for adsorbing the fuel vapor from the fuel tank, an air inlet port at a bottom portion of the canister, and an air inlet passage connecting the air inlet port to the atmosphere;

    a vapor passage connecting said fuel tank to said canister for feeding the fuel vapor from said fuel tank into said canister;

    a purge passage connecting said canister to an intake passage of the internal combustion engine for feeding the adsorbed fuel vapor in said adsorbent in said canister into said intake passage;

    a first control valve provided at an intermediate portion in said purge passage for controlling a flow of the adsorbed fuel vapor being fed, due to a vacuum pressure in said intake passage, from said canister to said intake passage;

    a second control valve provided in said air inlet passage of said canister for controlling a flow of external air being fed, due to a vacuum pressure in said vapor passage, into the vapor passage through the canister;

    a pressure sensor provided at an intermediate portion in said air inlet passage between said canister and said second control valve for outputting a signal indicating pressure in said air inlet passage;

    valve control means for controlling opening and closing operations of each of said first and second control valves when a malfunction detection is made; and

    malfunction detection means, responsive to said signal outputted by said pressure sensor, for determining whether there is a malfunction in said evaporated fuel purge system,wherein a malfunction detection is made by said malfunction detection means, both when the first and second control valves are closed by said valve control means, and when the second control valve is closed and the first control valve is opened by said valve control means.

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