The present invention relates to a valve assembly for controlling fluid flow to and from a high-pressure reservoir.
Valves are employed in a multitude of industries to control flow of liquids and/or gases. One application for such control valves appears in vehicles with stored fuel to control a vehicle's evaporative emissions resulting from gasoline vapors escaping from the vehicle's fuel system. Evaporative emissions of modern vehicles are strictly regulated in many countries. To prevent fuel vapors from venting directly to the atmosphere, a majority of vehicles manufactured since the 1970's include specifically designed evaporative emissions systems. Additionally, in recent years vehicle manufacturers began developing fully sealed fuel delivery to their engines.
In a typical evaporative emissions system, vented vapors from the fuel system are sent to a purge canister containing activated charcoal. The activated charcoal used in such canisters is a form of carbon that has been processed to make it extremely porous, creating a very large surface area available for adsorption of fuel vapors and/or chemical reactions. During certain engine operational modes, with the help of specifically designed control valves, the fuel vapors are adsorbed within the canister. Subsequently, during other engine operational modes, and with the help of additional control valves, fresh air is drawn through the canister, pulling the fuel vapor into the engine where it is burned.
An embodiment of the invention is a valve assembly for controlling fluid flow between a first reservoir and a second reservoir. The valve assembly includes a relief valve arranged inside the housing and configured to open the first fluid flow path when a pressure inside the first reservoir is above a first predetermined pressure value.
The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings.
Referring to the drawings wherein like reference numbers correspond to like or similar components throughout the several figures,
Evaporative emissions control system 16 includes a valve assembly 20. Valve assembly 20 is configured to control a flow of fuel vapor between the fuel tank 12 and the purge canister 18. Although valve assembly 20 as shown is located between fuel tank 12 and purge canister 18, nothing precludes locating the valve assembly in a different position, such as between the purge canister 18 and the engine 13. Valve assembly 20 includes a housing 22, which retains all internal components of the valve assembly in a compact manner. Housing 22 connects to fuel tank 12 via a connector 24, and to the purge canister via a connector 26. Housing 22 accommodates a relief valve 28. Relief valve 28 includes a piston 30, which may be formed from a suitable chemically-resistant material such as an appropriate plastic or aluminum. Relief valve 28 may also include a compliant seal 32, which may be formed from a suitable chemically-resistant elastomeric material. Seal 32 may be an inward-sloped dynamic pressure seal, i.e., such that the seal's outer edge or lip is angled toward a central axis Y1. In operation, seal 32 makes initial contact with the housing 22 along the seal's angled outer edge. After the initial contact with housing 22, the outer edge of seal 32 deflects to conform to the housing and hermetically closes a passage 34. The inward slope of the seal's outer edge provides enhanced control of fuel vapor flow at small openings between seal 32 and housing 22.
Piston 30 and seal 32 may be combined into a unitary piston assembly via an appropriate manufacturing process such as overmolding, as understood by those skilled in the art. Piston 30 and seal 32 are urged to close passage 34 by a spring 36. As shown in
The over-pressure condition of fuel tank 12 may depend on design parameters typically specified according to appropriate engineering standards and commonly includes a factor of safety to preclude operational failure of the fuel tank. Pressure in the fuel tank 12 may vary in response to a number of factors, such as the amount and temperature of the fuel contained therein. The first predetermined pressure value may be established based on the design parameters of the fuel tank 12 and of the engine's fuel delivery system, as well as based on empirical data acquired during testing and development.
Valve assembly 20 also includes a solenoid assembly 40 arranged inside housing 22, and adapted to receive electrical power from a vehicle alternator or from an energy-storage device (not shown), and be triggered or energized by a control signal from controller 14. Solenoid assembly 40 includes an armature 42, a solenoid spring 44, and a coil 46, as understood by those skilled in the art. Solenoid spring 44 is configured to generate a force sufficient to urge armature 42 out of the solenoid assembly 40, when the solenoid assembly is not energized. Coil 46 is configured to energize solenoid assembly 40, and to withdraw armature 42 into the solenoid assembly by overcoming the biasing force of spring 44.
Valve assembly 20 additionally may include a flow restrictor 50. Flow restrictor 50 is arranged inside the housing 22, and includes a piston 52 which may be formed from a suitable chemically-resistant material such as an appropriate plastic or aluminum. Flow restrictor 50 also includes a compliant seal 54, which may be formed from a suitable chemically-resistant rubber. Seal 54 is an inward-sloped dynamic pressure seal, i.e., such that the seal's outer edge or lip is angled toward a central axis Y2. In operation, seal 54 makes initial contact with the housing 22 along the seal's angled outer edge. After the initial contact with housing 22, the outer edge of seal 54 deflects to conform to the housing and to hermetically close a passage 56. The inward slope of the seal's outer edge provides enhanced control of fuel vapor flow at small openings between seal 54 and housing 22.
Similar to the piston 30 and seal 32 above, piston 52 and seal 54 may be combined into a unitary piston assembly via an appropriate manufacturing process such as overmolding. Piston 52 and seal 54 are urged to close passage 56 by the action of a spring 58. In the embodiment shown in
As shown in
The rate of fluid flow from fuel tank 12 may vary in response to a number of factors, such as the amount, temperature and pressure of the fuel contained therein. The predetermined reference value of the rate of fluid flow may be set at, for example, approximately 260 liters per minute (LPM), but may also be established in relation to a higher or a lower predetermined reference value. The reference value is typically predetermined or established in accordance with operating parameters of a particular engine's fuel delivery system, as understood by those skilled in the art. The predetermined rate of fluid flow, however, must be sufficiently high to compress spring 58 and thereby expose passage 56, and the rate of spring 58 should therefore be selected accordingly.
Piston 52 and seal 54 are urged to close passage 56 by a spring 58. Relief valve 28 is configured to open a third fuel vapor flow path represented by arrow 62A, as shown in
As shown in
The catch mechanism 74 is configured to permit the plunger 42B to move or translate away from the flow restrictor 50 for a distance 76 that is sufficient to open the third fuel vapor flow path 62B without the need for the piston 42A to also be displaced away from the flow restrictor. Therefore, the separate piston 42A and plunger 42B permit friction between the piston 42A and the bore 72 to not impact the initial opening of the third fuel vapor flow path 62B. A stop plate 78 is provided to limit travel of the piston 42A within the bore 72.
As shown in the embodiment of
As shown in
As noted above, relief valve 28 is additionally configured to open the third fuel vapor flow path being traversed by the fuel vapor flowing in the direction represented by arrow 62B when the fuel tank 12 is below a second predetermined pressure value (shown in
In the embodiments shown in
While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.
This application is a Continuation In Part of U.S. Utility application Ser. No. 12/749,924, filed Mar. 30, 2010, which claims the benefit of U.S. Provisional Application Ser. No. 61/171,548, filed Apr. 22, 2009, the disclosure of which is hereby incorporated by reference.
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Number | Date | Country | |
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Parent | 12749924 | Mar 2010 | US |
Child | 13011676 | US |