Abstract:
In accordance with the teachings of the present invention, a shut-off valve is disclosed that has particular application for opening and closing a high pressure compressed gas storage tank. In one embodiment, the valve includes a single sealing member and a bellows. High pressure is provided at inlet port to one side of the sealing member and a bellows chambers so that both sides of the sealing member are at high pressure to provide equalization. A spring bias is the sealing member against a valve seat in one direction. An electromagnetic coil is energized to draw the sealing member away from the valve seat against the bias of the spring.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a Divisional application of U.S. patent application Ser. No. 11/155,184, titled Hydrogen Valve with Pressure Equalization, filed Jun. 17, 2005. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     This invention relates generally to a valve including pressure equalization and, more particularly, to a shut-off valve for a compressed hydrogen tank, where the valve includes one valve seat and two inlet ports that provide pressure equalization so that the valve can be opened with reduced force at high inlet pressures.  
         [0004]     2. Discussion of the Related Art  
         [0005]     Hydrogen is a very attractive fuel because it is clean and can be used to efficiently produce electricity in a fuel cell. The automotive industry expends significant resources in the development of hydrogen fuel cell systems as a source of power for vehicles. Such vehicles would be more efficient and generate fewer emissions than today&#39;s vehicles employing internal combustion engines.  
         [0006]     A hydrogen fuel cell is an electro-chemical device that includes an anode and a cathode with an electrolyte therebetween. The anode receives hydrogen gas and the cathode receives oxygen or air. The hydrogen gas is dissociated in the anode to generate free hydrogen protons and electrons. The hydrogen protons pass through the electrolyte to the cathode. The hydrogen protons react with the oxygen and the electrons in the cathode to generate water. The electrons from the anode cannot pass through the electrolyte, and thus are directed through a load to perform work before being sent to the cathode. The work acts to operate the vehicle.  
         [0007]     Many fuel cells are typically combined in a fuel cell stack to generate the desired power. For example, a typical fuel cell stack for a vehicle may have two hundred or more stacked fuel cells. The fuel cell stack receives a cathode input gas, typically a flow of air forced through the stack by a compressor. Not all of the oxygen in the air is consumed by the stack and some of the air is output as a cathode exhaust gas that may include water as a stack by-product. The fuel cell stack also receives an anode hydrogen input gas that flows into the anode side of the stack.  
         [0008]     In some vehicle fuel cell systems, hydrogen is stored in one or more compressed gas tanks under high pressure on the vehicle to provide the hydrogen necessary for the fuel cell system. The pressure in the tank can be upwards of 700 bar. In one known design, the, compressed gas tank may include an inner plastic liner that provides a gas tight seal for the hydrogen, and an outer carbon fiber composite layer that provides the structural integrity of the tank. Because hydrogen is a very light and diffusive gas, the inner liner must be carefully engineered in order to act as a permeation barrier. The hydrogen is removed from the tank through a pipe. At least one pressure regulator is provided that reduces the pressure of the hydrogen within the tank to a pressure suitable for the fuel cell system.  
         [0009]     Further, a shut-off valve is required either in the tank or just outside of the tank that closes the tank when the fuel cell system is off. A stiff spring is typically used to maintain the valve in the closed position and prevent hydrogen leaks. Because the pressure in the compressed hydrogen tank may be very high, the pressure difference between the inlet side and the outlet side of the shut-off valve may be very large. Therefore, the force required to open the valve against the pressure difference and the spring bias is significant. Electromagnets are sometimes used in these types of shut-off valves to open the valve. However, electromagnets are generally not the most desirable valve choice because of the amount of energy required to open the valve, and the size and weight of the electromagnet.  
       SUMMARY OF THE INVENTION  
       [0010]     In accordance with the teachings of the present invention, a shut-off valve is disclosed that has particular application for opening and closing a high pressure compressed gas storage tank. In one embodiment, the valve includes a single sealing member and a bellows. High pressure is provided at an inlet port to one side of the sealing member and a bellows chambers so that both sides of the sealing member are at high pressure to provide equalization. A spring biases is the sealing member against a valve seat in one direction. An electromagnetic coil is energized to draw the sealing member away from the valve seat against the bias of the spring.  
         [0011]     Additional features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a cross-sectional view of a shut-off valve including two valve sealing members that provide pressure equalization, according to an embodiment of the present invention;  
         [0013]      FIG. 2  is a cross-sectional view of a shut-off valve including two valve sealing members for providing pressure equalization that has particular application for the inside of a high pressure gas storage tank, according to another embodiment of the present invention;  
         [0014]      FIG. 3  is a cross-sectional view of the shut-off valve shown in  FIG. 2  within the high pressure gas storage tank; and  
         [0015]      FIG. 4  is a cross-sectional view of a shut-off valve including a valve sealing member and a bellows for providing pressure equalization that has particular application for the inside of a high pressure gas storage tank, according to another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0016]     The following discussion of the embodiments of the invention directed to a shut-off valve that provides pressure equalization is merely exemplary in nature, and is in no way intended to limit the invention or its applications or uses. For example, the shut-off valve of the invention has particular application for a compressed hydrogen storage tank in a fuel cell system. However, as will be appreciated by those skilled in the art, the shut-off valve of the invention may have other applications.  
         [0017]      FIG. 1  is a cross-sectional view of a shut-off valve  10  that has application for opening and closing a compressed hydrogen storage tank in a fuel cell system, according to an embodiment of the present invention. The shut-off valve  10  includes a valve body  12  mounted to a flange  20  of a cylindrical support member  14  by bolts  16 . An electromagnetic coil  18  is wound around the member  14 , as shown. The member  14  includes an internal bore  22  in which is positioned a cylindrical pole piece member  24  also having an internal bore  26 . A spring  28  is positioned within the bore  26  against an inside surface of the cylindrical member  14 , as shown. A shaft  32  is mounted to the pole piece member  24  opposite to the spring  28 , and extends into a valve chamber  34  within the body  12 .  
         [0018]     The body  12  includes a first valve seat  42  and a second valve seat  44 . A first annular sealing member  46  is mounted to the shaft  32  proximate the valve seat  42  and a second annular sealing member  48  is mounted to the shaft  32  proximate the valve seat  44 . The body  12  also includes two inlet ports  36  and  38  and one outlet port  40 . The inlet ports  36  and  38  are at tank pressure, which may be upwards of 700 bar for a compressed hydrogen tank associated with a fuel cell system. This pressure from the inlet ports  36  and  38  is introduced into the chamber  34  so that it forces the sealing member  46  against the valve seat  42  and the sealing member  48  away from the valve seat  44 . This configuration provides the pressure equalization of the valve  10 . The bias of the spring  28  in combination with the pressure equalization from the inlet ports  36  and  38  forces the sealing member  46  to seat against the valve seat  42  and the sealing member  48  to seat against the valve seat  44  when the coil  18  is not energized. This is the default closed position of the valve  10  when hydrogen flow is not desired.  
         [0019]     The electromagnetic coil  18  is energized to open the shut-off valve  10 . The magnetic field generated by the coil  18  moves the pole piece member  24  and the shaft  32  against the bias of the spring  28  so that the sealing member  46  moves away from the valve seat  42  and the sealing member  48  moves away from the valve seat  44 . Therefore, hydrogen entering the inlet ports  36  and  38  is allowed to flow through the chamber  34  and out of the outlet port  40 . Because of the pressure equalization, the electromagnetic force provided by the coil  18  does not need to overcome the pressure within the tank, and therefore the amount of energy required to open the valve  10  against the bias of the spring  28  does not need to be significant.  
         [0020]     The shut-off valve  10  has particular application for a compressed hydrogen tank where the valve  10  would be positioned outside of the tank. However, in other designs, it may be desirable to provide the shut-off valve within the tank.  FIG. 2  is a cross-sectional view of a shut-off valve  60  similar to the valve  10  that provides pressure equalization, and is designed for the inside of a pressure tank, according to another embodiment of the present invention.  FIG. 3  is a cross-sectional view of the valve  60  positioned within a pressure tank  62 , where the shut-off valve  60  is mounted within a bore  64  of an adapter  66 . The adapter  66  connects the pressure tank  62  to the outside environment. The adapter  66  may contain several components, such as sensors, valves, filters, etc., depending on the particular design. In this embodiment, a valve body  68  of the valve  60  is positioned within the bore  64 . The valve body  68  includes a valve chamber  70 , a first valve seat  72  and a second valve seat  74 . An outlet port  86  extends through the adapter  64  to the outside environment to remove hydrogen from the tank  62 .  
         [0021]     The valve body  68  is mounted to a flange  76  of a cylindrical member  78 . An internal bore  80  extends completely through the member  78 . A cylindrical pole piece member  82  is positioned within an expanded portion  88  of the bore  80  proximate the valve body  68 , as shown. The pole member  82  includes orifices  84  that allow the bore  80  to be in fluid communication with the chamber  70 . A shaft  90  is mounted to the pole member  82 , where the shaft  90  includes an internal bore  92  also in fluid communication with the bore  80  through a central bore  94  of the member  82 . A filter  96  is mounted over the bore  80  at an open end of the member  78  to prevent particles and the like from entering the bore  80 .  
         [0022]     A first annular sealing member  100  is mounted to the shaft  90  proximate the valve seat  72  and a second annular sealing member  102  is mounted to the shaft  90  proximate the valve seat  74 . A spring  104  is positioned in the chamber  70  between and in contact with the sealing member  100  and the pole member  82 , as shown. An electromagnetic coil  106  is wrapped around the cylindrical member  78  and is used to open the valve  60 .  
         [0023]     The valve  60  is shown in its closed position where the coil  106  is not energized so that the spring  104  forces the first sealing member  100  against the first valve seat  72  and the second sealing member  102  against the second valve seat  74 . Hydrogen pressure within the tank  62  enters the bore  80  through the filter  96 , then through the bore  94 , and through the orifices  84  to apply pressure in combination with the spring bias  104  against the sealing member  100  to force it against the valve seat  72 . The hydrogen pressure within the tank  62  also enters a sub-chamber  110  in the valve chamber  70  through the bore  92  to force the sealing member  102  away from the valve seat  74 . Therefore, the high pressure within the tank  62  is equalized by this configuration. When the valve  60  is to be opened, the coil  106  is energized which magnetically draws the pole member  82  towards the left against the bias of the spring  104  to lift the sealing member  100  off the valve seat  72  and the sealing member  102  off the valve seat  74  to allow the hydrogen to flow from the chamber  70  into the outlet port  74 .  
         [0024]      FIG. 4  is a cross-sectional view of a shut-off valve  120  similar to the shut-off valve  60 , where like elements are identified by the same reference numeral, according to another embodiment of the invention. In this embodiment, the second sealing member  102  and the second valve seat  74  are eliminated, and are replaced with a bellows  122 . The bellows  122  is mounted to the valve body  68  and an end of the valve shaft  90  to create a bellows chamber  124 . When the valve  120  is closed, high pressure from the tank  62  pushes the sealing member  100  against the valve seat  72 , and provides pressure to the bellows chamber  124 . The pressure in the bellows chamber  124  pushes against an opposite side of the sealing member  100  away from the valve seat  72  to provide the pressure equalization, as discussed above. When the coil  106  is energized, the pole member  82  and the shaft  90  move to the left causing the bellows  122  to contract. Because the valve  120  only has one valve seat, high precision production processes are not required.  
         [0025]     The foregoing discussion discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the spirit and scope of the invention as defined in the following claims.