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Fuel tank vapor flow control valve

  • US 4,153,025 A
  • Filed: 12/02/1977
  • Issued: 05/08/1979
  • Est. Priority Date: 12/02/1977
  • Status: Expired due to Term
First Claim
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1. In an evaporative emission control system for an internal combustion engine having a fuel tank for supplying fuel to the throttle valve controlled induction passage of the engine, a vapor storage canister used to store fuel vapor for delivery to the induction passage of the engine during engine operation, and a vent conduit means with a vapor flow control valve therein connecting a fuel vapor passage of the fuel tank to the inlet of the vapor storage canister, the improvement wherein said vapor flow control valve, for controlling flow of fuel vapor from the fuel tank to the vapor storage canister, includes a housing providing an internal cavity with an upstanding boss having a valve seat at one end and having a passage therein extending through said valve seat to be in communication with said cavity, valve means including a diaphragm positioned in said housing to divide said cavity into a vapor chamber on the one side thereof adjacent said valve seat and a vacuum chamber on the other side thereof, said housing having a vapor inlet to said vapor chamber connected to the fuel vapor passage of the fuel tank, an outlet connected at one end to said passage and its other end in communication with the inlet of the vapor storage canister, said valve means being movable in said housing relative to said valve seat between a first position blocking flow from said vapor chamber to said passage and a second position permitting vapor flow from said vapor chamber into said passage to said outlet, said valve means including spring means of a first predetermined force operatively positioned whereby said valve means is normally biased to said first position, a vacuum port in said housing opening at one end into said vacuum chamber and operatively connected at its other end to the induction passage downstream of the throttle valve whereby during engine operation manifold vacuum is applied to one side of said diaphragm to effect movement of said valve means to said second position when manifold vacuum is above a predetermined value, said valve means also being movable to said second position by fuel vapor pressure above a predetermined pressure acting on the side of the diaphragm exposed to the vapor chamber and, controlled flow passage means including a sized orifice passage in said housing providing a secondary vapor flow connection between said vapor chamber and said outlet.

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