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

• Current Assignee: General Motors Corporation (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Thornburgh, William F.
• Primary Examiner(s): Cox, Ronald B.
• Application Number:
  US05/856,654
• Time in Patent Office: 522 Days
• Field of Search: 123/136
• US Class Current: 123/520
• CPC Class Codes: F02M 25/0872 Details of the fuel vapour pipes or conduits

Abstract

In an evaporative emission control system for a vehicle, the flow of fuel vapor from the fuel tank to the vapor storage canister in the system is controlled by a vapor flow control valve having a housing with a chamber therein in flow communication with the fuel tank to receive fuel vapor therefrom this chamber being connected to the vapor storage canister by a first vapor passage means and by a second vapor passage means, with flow from the chamber through the first vapor passage means being controlled by a diaphragm valve means that is normally biased closed by a spring, and which is responsive to either engine vacuum on one side thereof or to a predetermined fuel vapor pressure on its opposite side whereby to permit vapor flow and, the second vapor passage means including a sized bleed orifice passage used to control the rate of vapor flow to the storage canister via this second vapor passage means.

Claims

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.

2. In an evaporative emission control system according to claim 1 wherein said controlled flow passage means of said vapor flow control valve further includes a second valve seat at the opposite end of said boss with a flow passage means extending therethrough in communication with said sized orifice passage, a diaphragm valve means positioned in said housing to further divide said cavity into said vapor chamber on one side of said diaphragm valve means and an atmospheric pressure chamber on the opposite side of said diaphragm valve means, said housing having an aperture means therein to effect communication between said pressure chamber and the atmosphere, said diaphragm valve means being movable in said housing relative to said second valve seat between a first position blocking flow from said vapor chamber to said flow passage and a second position permitting flow from said vapor chamber to said flow passage and a second spring means, of a second predetermined force less than said predetermined force of said spring means, operatively positioned relative to said diaphragm valve means to normally bias said diaphragm valve means to said second position.

3. In an evaporative emission control system for an internal combustion engine having an induction system with flow therethrough controlled by a throttle valve and including a fuel tank for supplying fuel to the engine, a vapor storage canister to store fuel vapors for delivery to the engine, the fuel tank having a vapor passage connected by vent means including a vapor flow control valve to a vapor inlet of the vapor storage canister, the improvement wherein said vapor flow control valve includes a housing having a cavity therein with an inlet means thereto operatively connected to the vapor passage of the fuel tank and an outlet means therefrom operatively connected to the vapor inlet of the vapor storage canister, a diaphragm actuated valve means positioned in said housing to divide said cavity into a vacuum chamber on one side of said diaphragm actuated valve means and operative between a closed position and an open position to control vapor flow from said inlet to said outlet, spring means operatively positioned in said housing to normally bias said diaphragm actuated valve means to said closed 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 system downstream of the throttle valve whereby during engine operation induction vacuum is applied to said one side of said diaphragm actuated valve means for moving said diaphragm actuated valve means to said open position during engine operation, said diaphragm actuated valve means also being movable to said open position when the fuel vapor pressure in said inlet means reaches some predetermined pressure to overcome the bias action of said spring means and, a controlled flow passage means including a sized orifice passage in said housing providing a secondary flow connection between said inlet means and said outlet means.

4. In an evaporative emission control system according to claim 3 wherein said controlled flow passage means of said vapor flow control valve further includes a pressure actuated valve means controlling flow through said controlled flow passage means upstream of said sized orifice passage in terms of the direction of flow from said inlet means to said outlet means, said pressure actuated valve means being operable to permit vapor flow through said controlled flow passage means when the fuel vapor pressure in said inlet means reaches some second predetermined pressure, said second predetermined pressure being less than said predetermined pressure required for actuating said diaphragm actuated valve to said open position.