Abstract:
A valve mechanism is disclosed, the valve mechanism including a rotor and stator adapted for selectively providing a flow of hydrogen to and selectively bleeding the hydrogen from a plurality fuel cell stacks.

Description:
FIELD OF THE INVENTION 
     The invention relates generally to a fuel cell system valve mechanism, and more particularly, to a valve mechanism adapted for selectively providing a flow of hydrogen to and selectively bleeding the hydrogen from a plurality fuel cell stacks. 
     BACKGROUND OF THE INVENTION 
     Fuel cells have been proposed as a power source for electric vehicles and other applications. In proton exchange membrane (PEM) type fuel cells, hydrogen is supplied to an anode of the fuel cell and oxygen is supplied as an oxidant to a cathode. A typical fuel cell system includes a plurality of fuel cells stacked together in a fuel cell stack. Typically, numerous fuel cell stacks are required to power a fuel cell powered vehicles. Large amounts of hydrogen, stored in fuel tanks on an undercarriage of the vehicle, are supplied to each of the fuel cell stacks to power the vehicle. 
     Current fuel cell systems include a valve mechanism associated with an inlet and a bleed conduit of the anode subsystem of each fuel cell stack. As many as eight valve mechanisms may be required to properly supply hydrogen to and bleed hydrogen from the fuel cell stacks. Each valve mechanism may include associated components, such as an injector, a solenoid, and a control system, for example. Numerous valve mechanisms and associated components occupy a relatively large amount of space in the fuel cell vehicle. 
     It would be desirable to develop an improved anode subsystem valve mechanism adapted for selectively providing a hydrogen flow to and selectively bleeding the hydrogen from a plurality of fuel cell stacks. 
     SUMMARY OF THE INVENTION 
     Concordant and congruous with the present invention, an anode subsystem valve mechanism adapted for selectively providing a hydrogen flow to and selectively bleeding the hydrogen from a plurality of fuel cell stacks, has surprisingly been discovered. 
     In one embodiment, A valve mechanism comprises a valve body having an inlet in fluid communication with a source of fluid; an actuator disposed in said valve body; a stator disposed in said body valve and having a plurality of apertures; and a rotor having a flow channel formed therein, said rotor rotatably connected to said actuator and disposed between said actuator and said stator in said valve body, rotation of said rotor facilitating selective flow of a fluid from the fluid source, through said valve body, through at least one of the apertures, and selectively to one of a plurality of fuel cell stacks. 
     In another embodiment, A fuel cell system comprises a plurality of fuel cell stacks; a valve body having an inlet in fluid communication with a fluid, disposed adjacent said actuator; an actuator disposed in said valve body; a stator disposed in said valve body having a plurality of apertures, wherein the plurality of apertures includes at least a first flow aperture in fluid communication with a first fuel cell stack and a second flow aperture in fluid communication with a second of fuel cell stack; and a rotor having a flow channel formed therein, said rotor rotatably connected to said actuator and disposed between said actuator and said stator in said valve body, rotation of said rotor facilitating selective flow of a fluid from the fluid source, through said valve body, selectively through at least one of the flow apertures, and to one of a plurality of fuel cell stacks, wherein the flow channel of said rotor is positioned over the plurality of apertures to selectively permit a flow of the fluid to or a bleed of the fluid from the plurality of fuel cell stacks. 
     In another embodiment, A valve mechanism comprises a valve body having an inlet in fluid communication with a fluid, disposed adjacent said actuator; an actuator disposed in said valve body; a stator having a first flow aperture, a second flow aperture, a first bleed aperture, and a second bleed aperture, wherein the first flow aperture is in fluid communication with a first fuel cell stack and the second flow aperture is in fluid communication with a second fuel cell stack; a rotor having a flow channel formed therein, said rotor rotatably connected to said actuator and disposed between said actuator and said stator in said valve body, rotation of said rotor facilitating selective flow of a fluid from the fluid source, through said valve body, selectively through at least one of the flow apertures, and to one of a plurality of fuel cell stacks, wherein the flow channel of said rotor is positioned over the plurality of apertures to selectively permit a flow of the fluid to or a bleed of the fluid from the plurality of fuel cell stacks. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which: 
         FIG. 1  is an exploded perspective view of a valve mechanism according to an embodiment of the invention; 
         FIG. 2  is an end view of a stator of the valve mechanism of  FIG. 1 ; 
         FIG. 3  is an elevational view of a rotor of the valve mechanism of  FIG. 1 ; 
         FIG. 4   a  is an elevational view of the rotor and the stator shown in  FIG. 1  illustrating the valve mechanism in a first position; 
         FIG. 4   b  is an elevational view of the rotor and the stator shown in  FIG. 1  illustrating the valve mechanism in a second position; 
         FIG. 4   c  is an elevation view of the rotor and the stator shown in  FIG. 1  illustrating the valve mechanism in a third position; 
         FIG. 4   d  is an elevational view of the rotor and the stator shown in  FIG. 1  illustrating the valve mechanism in a fourth position; 
         FIG. 5  is a schematic view of a plurality of fuel cell stacks with a sectional view of the valve mechanism of  FIG. 1 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following detailed description and appended drawings describe and illustrate various exemplary embodiments of the invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner. 
       FIG. 1  shows a valve mechanism  10  according to an embodiment of the invention. The valve mechanism  10  includes an actuator  12 , a valve body  14 , a stator  16 , and a rotor  18 . It is understood that the valve mechanism  10  may be formed any conventional material such as steel, a steel alloy, a ceramic composite, a plastic composite, and a combination thereof, for example. 
     The actuator  12  is disposed in the valve body  14  of the valve mechanism  10  and is connected to the rotor  18  by a rotatable axle  20 . It is understood that the actuator  12  may be any conventional actuator such as a rotary solenoid, a DC motor, a stepper motor, or a torque motor, for example. It is further understood that the actuator  12  may be disposed outside and adjacent to the valve mechanism  10  as desired. 
     The valve body  14  includes an inlet  22  in fluid communication with a source (not shown) of a first fluid (not shown). The first fluid may be any fluid such as hydrogen, oxygen, nitrogen, or air, for example. In the embodiment shown, the valve body  14  has a generally cylindrical shape with a circular cross-sectional shape. The valve body  14  forms a cavity  32  adapted to receive the actuator  12 , the stator  16 , and the rotor  18 . It is understood that the valve body  14  may have any shape, as desired. It is further understood that the actuator  12 , the stator  16 , and the rotor  18  may be fully disposed in, partially disposed in, or substantially abutting an exterior of the valve body  14 , as desired. 
     The stator  16  includes a first flow aperture  24 , a second flow aperture  26 , a first bleed aperture  28 , and a second bleed aperture  30 . In the embodiment shown, the stator  16  is disposed in the valve body  14  of the valve mechanism  10  and abuts the rotor  18 , also disposed in the valve body  14 . As shown in  FIG. 5 , the first flow aperture  24  is in fluid communication with an anode side (not shown) of a first fuel cell stack  40 , and the second flow aperture  26  is in fluid communication with an anode side (not shown) of a second fuel cell stack  42 . The first bleed aperture  28  and the second bleed aperture  30  are in fluid communication with the fuel cell system exhaust which is in communication with ambient air. It is understood that the bleed apertures  28 ,  30  may be in fluid communication with the first and the second fuel cell stacks  40 ,  42  and the ambient air, as desired. As shown in  FIG. 2 , the stator  16  has a substantially circular shape. It is understood that the stator  16  may have any shape, as desired. The flow apertures  24 ,  26  are substantially circular. The bleed apertures  28 ,  30  are substantially circular and have a diameter less than a diameter of the flow aperture  24 ,  26 . It is understood that the apertures,  24 ,  26 ,  28 ,  30  may have any shape and diameter, as desired. 
     The rotor  18  includes a flow channel  34  is connected to the axle  20  of the actuator  12  to be rotatable therewith. The rotor  18  is disposed in the cavity  32  of the valve body  14  substantially abutting the stator  16 . As shown in  FIG. 3 , the rotor  18  has a circular shape with a circle sector  36  removed. A circle sector, also known as a pie piece, is defined as the portion of a circle enclosed by two radii and an arc. It is understood that the rotor  18  may have any shape, as desired. It is further understood that the portion of the rotor  18  removed may have any shape, such as a crescent shape, a substantially triangular shape, and a substantially rectangular shape, for example. A flow channel  34  is formed in a surface of the rotor  18 . In the embodiment shown, the flow channel  34  is substantially a y-shaped, however, it is understood that the flow channel  34  may have any shape such as a t-shape and a v-shape, for example. 
     Generally, during operation of a fuel cell power system, such as the fuel cell power system of U.S. Pat. No. 6,939,631 for FUEL CELL SYSTEM AND METHOD OF OPERATION hereby incorporated by reference, a stream of hydrogen is fed into the anode side of the fuel cell stack. Concurrently, a stream of oxygen is fed into the cathode side of the fuel cell stack. On the anode side, the hydrogen in the hydrogen stream is catalytically split into protons and electrons. The oxidation half-cell reaction is represented by: H 2             2H + +2e − . In a polymer electrolyte membrane fuel cell, the protons permeate through the membrane to the cathode side. The electrons travel along an external load circuit to the cathode side creating the current of electricity of the fuel cell stack. On the cathode side, the oxygen in the oxidant stream reacts with the protons permeating through the membrane and the electrons from the external circuit to form water molecules. This reduction half-cell reaction is represented by: 4H + +4e − +O 2           2H 2 O. Anode exhaust from the anode side flows through a backpressure control valve (not shown) to a combustor. Cathode exhaust from the cathode side flows through a second backpressure control valve (not shown) to the combustor. A control module (not shown) regulates the conditions of the hydrogen stream, oxygen stream, and exhaust streams by operating various control valves (not shown), backpressure control valves (not shown), and compressors (not shown) in response to signals from pressure sensors (not shown) and electrical power sensors (not shown) connected to the fuel cell stacks  40 ,  42 .
     During operation of the fuel cell system, the valve mechanism  10  is in fluid communication with the hydrogen source, the first fuel cell stack  40 , and the second fuel cell stack  42 . A stream of hydrogen is caused to flow from the hydrogen source and through the inlet  22  into the valve mechanism  10 . As the hydrogen flows into the valve mechanism  10 , the actuator  12  is caused to rotate the rotor  18  by a controller (not shown). The rotor  18  is caused to rotate relative to the stator  16  to one of four positions based on input from the controller. It is understood that the number of positions in which the rotor  18  may be positioned depends upon the size and shape of the rotor, the number of fuel cell stacks to be supplied with hydrogen, and other similar design considerations. It is further understood that the controller may cause the actuator  12  to rotate the rotor based on a desired flow to the first fuel cell stack  40  or the second fuel cell stack  42 , whether the fuel cell stacks  40 ,  42  are cold-starting or are at steady state, and other control variables, as desired. By providing fluid communication between the hydrogen source and each of the first fuel stack and the second fuel stack through the valve mechanism  10 , a redundancy of valve mechanisms, conduit systems, and other components is avoided and the space occupied by the valve mechanism is minimized. 
     In a first position shown in  FIG. 4   a , the rotor  18  is caused to block the second flow aperture  26 , the first bleed aperture  28 , and the second bleed aperture  30  of the stator  16 . The circle sector  36  is positioned over the first flow aperture  24 . With the circle sector  36  over the first flow aperture  24 , hydrogen is allowed to flow from the source, through the inlet  22 , through the valve mechanism  10  and the first flow aperture  24 , and to the first fuel cell stack  40 . 
     In a second position shown in  FIG. 4   b , the rotor  18  is caused to block the first bleed aperture  28 , while the flow channel  34  of the rotor  18  is positioned over the second flow aperture  26  and the second bleed aperture  30 . The circle sector  36  is positioned over the first flow aperture  24  to allow fluid communication between the first flow aperture  24  and the valve mechanism  10 . The second position allows a flow of hydrogen from the hydrogen source, through the valve mechanism  10 , and to the first fuel cell stack  40  while simultaneously allowing a bleed of hydrogen fluid from the second fuel cell stack  42  through the second flow aperture  26 , through the flow channel  34 , and out of the valve mechanism  10  through the second bleed aperture  30 . 
     In a third position shown in  FIG. 4   c , the rotor  18  is caused to block the first flow aperture  24 , the first bleed aperture  28 , and the second bleed aperture  30  of the stator  16 . The circle sector  36  is positioned over the second flow aperture  26 . With the circle sector  36  positioned over the second flow aperture  30 , hydrogen is allowed to flow from the source, through the inlet  22 , through the valve mechanism  10  and the first flow aperture  24 , and to the second fuel cell stack  42 . 
     In a fourth position shown in  FIG. 4   d , the rotor  18  is caused to block the second bleed aperture  30 , while the flow channel  34  of the rotor  18  is positioned over the first flow aperture  24  and the first bleed aperture  28 . The circle sector  36  is positioned over the second flow aperture  26  to allow fluid communication between the second flow aperture  26  and the valve mechanism  10 . The fourth position allows a flow of hydrogen from the hydrogen source to the second fuel cell stack  42  while simultaneously allowing a bleed of hydrogen fluid from the first fuel cell stack  40  through the first flow aperture  26 , through the flow channel  34 , and out of the valve mechanism  10  through the first bleed aperture  28 . 
     By proving a single valve mechanism  10  in fluid communication with the hydrogen source and each of the first fuel stack and the second fuel stack, a redundancy of valve mechanisms, conduit systems, and other components is avoided. By minimizing redundant components, the space occupied by the components is minimized thereby maximizing the space available to be occupied by a fuel tank (not shown), the first fuel stack, the second fuel stack, or other system components, as desired. Additionally, a single actuator  12  is provided to control the valve mechanism  10  thereby reducing the number of actuators required and further maximizing the space available for other system components. By minimizing the number of actuators and valve mechanisms adapted to regulate the hydrogen feed, the overall control of the hydrogen feed and the hydrogen bleed is simplified. 
     From the foregoing description, one ordinarily skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications to the invention to adapt it to various usages and conditions.