Freeze-tolerant valve
View Patent ↗A valve for reducing the likelihood of ice-related blockage in a fuel cell and methods for starting a fuel cell system. The valve includes a valve plate and coupling plate that are cooperative with one another within a valve body such that flexural forces imparted to the valve plate from a pressurized fluid are transferred to localized contact surfaces between the valve plate and coupling plate. By concentrating these forces to such a localized area, improvements in the ability of the fluid to initiate and propagate a crack in built-up ice around the valve's seating region is improved. In this way, fuel cell starting in cold conditions—such as those associated with temperatures at or below the freezing point of water—is also improved.
1. A flow-control valve for a fuel cell system, said valve comprising:
a fluid inlet configured to receive a fuel cell reactant;
a fluid outlet disposed fluidly downstream of said fluid inlet;
a body defining a fluid reactant passageway therethrough that is cooperative with said fluid inlet and said fluid outlet, said body having a valve seat within said fluid reactant passageway between said fluid inlet and fluid outlet;
a generally rigid coupling plate adjacent said valve seat, said coupling plate including one or more protruding tabs;
a biasing member biasing said coupling plate towards said valve seat and
a valve plate seated on said valve seat interposed between said coupling plate and said body, said valve plate defining a seating region adjacent said coupling plate and having a localized connection surface with one or more apertures receiving therein the one or more tabs of said coupling plate, the localized connection surface pressing against said body and said coupling plate to define a point of inflection within said valve plate such that a flexural force induced in said valve plate by a load imparted thereto causes a moment to form at said localized connection surface to thereby initiate a breakup of ice formed at said localized connection surface.
2. The valve of claim 1 , further comprising an actuating diaphragm cooperative with said valve plate to provide selective actuation thereto.
3. The valve of claim 2 , wherein said seating region defines a substantially curvilinear shape about its periphery.
4. The valve of claim 1 , wherein said valve seat is substantially cylindrical.
5. The valve of claim 1 , wherein said biasing member includes a bias spring pressing said valve plate into a deformed state during a closed state of said valve.
6. The valve of claim 1 , further comprising an actuation member disposed within said body, said actuation member configured to provide a pressure balance within said valve through a bias force imparted to at least one of said valve plate and said coupling plate.
7. The valve of claim 6 , wherein said actuation member comprises a flexible diaphragm abutting said coupling plate, and wherein during a closed state of said valve, said diaphragm substantially prevents said fuel cell reactant from flowing between said fluid inlet and said fluid outlet through said fluid reactant passageway, said diaphragm further configured such that during an open state of said valve, said valve plate becomes unseated to permit said fuel cell reactant to flow between said fluid inlet and said fluid outlet through said fluid reactant passageway.
8. The valve of claim 6 , wherein said actuation member comprises an electrical stepper motor, brushed motor, brushless motor, or solenoid selectively cooperative with said coupling plate such that during a closed state, said stepper motor substantially prevents said fuel cell reactant from flowing between said fluid inlet and said fluid outlet through said fluid reactant passageway, said stepper motor further configured such that during an open state, said stepper motor causes said valve plate to become unseated to permit said fuel cell reactant to flow between said fluid inlet and said fluid outlet through said fluid reactant passageway.
9. A fuel cell system comprising:
at least one fuel cell comprising an anode configured to accept a hydrogen-bearing reactant, a cathode configured to accept an oxygen-bearing reactant, and a medium cooperative with said anode and said cathode such that upon catalytic transformation of at least one of said reactants, said catalytically-transformed reactant travels from one of said anode and said cathode to another of said cathode and said anode through said medium;
an anode flow path in fluid communication with said anode:
a cathode flow path in fluid communication with said cathode, each of said anode flow path and said cathode flow path being cooperative with a respective fluid inlet configured to receive a fuel cell reactant and a respective fluid outlet disposed fluidly downstream of said fluid inlet; and
at least one valve disposed in at least one of said anode flow path and said cathode flow path and defining a fluid reactant passageway therethrough, said at least one valve comprising:
a fluid inlet,
a fluid outlet,
a body defining a fluid reactant passageway therethrough that is cooperative with said fluid inlet and said fluid outlet, said body having a valve seat within the fluid reactant passageway between the fluid inlet and fluid outlet,
an actuation member configured to bias said valve in a preferred position,
a generally rigid coupling plate adjacent said valve seat, said coupling plate including one or more protruding tabs, and
a valve plate seated on said valve seat interposed between said coupling plate and said body, said valve plate defining a seating region adjacent said coupling plate and having a localized connection surface with one or more apertures receiving therein the one or more tabs of the coupling plate, the localized connection surface pressing against said body and said coupling plate to define a point of inflection within said valve plate such that a flexural force induced in said valve plate by a load imparted thereto causes a moment to form at said localized connection surface to thereby initiate a breakup of ice formed at said localized connection surface.
10. The system of claim 9 , further comprising a humidification device placed in fluid communication with at least said cathode flow path such that moisture differentials between a portion of said cathode flow path upstream of said at least one fuel cell and a portion of said cathode flow path downstream of said at least one fuel cell may be reduced through operation of said humidification device.
11. The system of claim 10 , wherein said at least one valve is placed fluidly between said humidification device and an inlet to said cathode flow path.
12. The system of claim 10 , wherein said at least one valve is placed fluidly between said humidification device and an outlet to said cathode flow path.
13. The system of claim 10 , wherein said at least one valve comprises a plurality of valves a first of which is placed fluidly between said humidification device and an inlet to said cathode flow path, and a second of which is placed fluidly between said humidification device and an outlet to said cathode flow path.
14. The system of claim 10 , wherein said at least one valve is placed fluidly between said humidification device and an inlet to said cathode flow path and between said humidification device and an outlet to said cathode flow path.
15. The system of claim 14 , further comprising a back pressure valve fluidly cooperative with said at least one fuel cell to permit a pressure source that is also fluidly cooperative with said at least one fuel cell to build up pressure in said reactant.
16. The system of claim 10 , wherein said at least one valve comprises a plurality of valves comprising:
an inlet valve that is placed fluidly upstream of a dry side of a water vapor transfer unit; and
an outlet valve that is placed fluidly downstream of a wet side of said water vapor transfer unit.
17. The system of claim 10 , wherein said at least one valve comprises a substantial entirety of selective fluid isolation between said at least one fuel cell and said humidification device.
18. The system of claim 9 , wherein said localized connection surface comprises a plurality of tab regions each of which comprises a joining location between said valve plate and said coupling plate such that said initiation of said ice breakup within said localized connection surface takes place adjacent said joining location due to flexural forces imparted to said valve plate.
19. A method of inhibiting freeze-related blockage of a reactant flow path in an automotive fuel cell system, said method comprising:
configuring a valve to be fluidly cooperative with said reactant flow path, said valve comprising:
a fluid inlet configured to receive a fuel cell reactant;
a fluid outlet fluidly downstream of said fluid inlet;
a body defining a fluid reactant passageway therethrough that is cooperative with said fluid inlet and said fluid outlet, said body having a valve seat within said fluid reactant passageway between said fluid inlet and fluid outlet;
an actuation member configured to bias said valve in a preferred position;
a generally rigid coupling plate adjacent said valve seat, said coupling plate including one or more protruding tabs; and
a valve plate seated on said valve seat interposed between said coupling plate and said body, said valve plate defining a seating region adjacent said coupling plate and having a localized connection surface with one or more apertures receiving therein the one or more tabs of the coupling plate, the localized connection surface pressing against said body and said coupling plate to define a point of inflection within said valve plate; and
introducing at least one of a hydrogen-bearing reactant and an oxygen-bearing reactant to said valve plate such that a flexural force induced in said valve plate by said reactant causes a moment to form at said localized connection surface to initiate a breakup of ice formed at said localized connection surface prior in time to a breakup of any ice formed in a substantial remainder of said seating region.
20. The method of claim 19 , wherein said flexural force induced in said valve plate takes place commensurate with or prior to movement of said valve between a closed valve state and an open valve state.
21. The method of claim 19 , wherein said localized connection surface comprises at least one tab region which comprises a joining location between said valve plate and said body such that said initiation of said ice breakup within said localized connection surf ace takes place adjacent said joining location due to flexural forces imparted to said valve plate.
22. The method of claim 19 , wherein said inhibiting freeze-related blockage is performed during a fuel cell stack cold start in an environmental condition where moisture present in a reactant flowstream may be prone to freezing.