Patent Application
20090014089
The present invention relates to a valve which is able to adjust a flow rate of fluid to a secondary side, a valve controller for the valve, and a fuel cell system provided with the valve.
Hitherto, supply systems supplying fuel stored in a tank to a fuel consuming apparatus are widely known. For example, in a supply system described in Japanese Patent Publication No. 2005-42924, hydride fluid stored in a tank is supplied to semiconductor manufacturing equipments. The tank is provided with a mechanical type regulator valve for adjusting the pressure of the hydride fluid supplied from the tank to the exterior.
However, it is not possible to precisely adjust the flow rate of fuel from tank by the use of the regulator valve attached to the tank. In addition, since the regulator valve is of a mechanical type, the response property is relatively low.
An object of the invention is to provide a valve being able to adjust a flow rate of fluid from a tank, a valve controller for the valve, and a fuel cell system having the valve.
In order to accomplish the above object, a valve according to the invention is configured to adjust a flow rate of fluid to a secondary side and is disposed on a tank so that the secondary side is a discharge side for fluid from inside the tank. The valve is configured so that the flow rate of the fluid from the tank is adjusted by a duty control.
According to the configuration, since the valve which is able to adjust the flow rate of the fluid by the duty control is disposed on the tank, it is possible to adjust the flow rate of the fluid from the tank at high accuracy.
Here, the configuration in which the valve is disposed on the tank can employ a configuration in which the valve is disposed inside the tank, a configuration in which the valve is directly or indirectly attached to an element of the tank and is disposed outside the tank, or a configuration in which a part of the valve is disposed inside the tank and the other of the valve is disposed outside the tank. In arranging the valve, the valve may be attached to a mouthpiece of the tank, or the valve and another valve may form a valve assembly and the valve assembly may be screwed to be engaged in the mouthpiece of the tank.
Preferably, the valve may further include a flow rate adjusting mechanism to adjust the flow rate by the duty control. The flow rate adjusting mechanism may be configured to block the discharge of the fluid from the tank.
According to the configuration, the valve may be made to serve as a shutoff valve.
Here, the flow rate adjusting mechanism may include a valve body, a valve seat which the valve body comes into contact/breaks contact with, and a solenoid for urging the valve body in directions in which the valve body comes into contact/breaks contact with the valve seat. In this configuration, an axial direction of the valve is in coincidence with a direction in which the valve body comes into contact/breaks contact with the valve seat. It is preferable that the valve seat may be more elastic than a base member of the valve or the valve body. Accordingly, it is possible to improve the function of the valve as a shutoff valve. It is preferable that the valve has such a configuration that the valve body comes into contact with the valve seat with the pressure (primary pressure) of the tank to block the discharge of the fluid.
Preferably, the axis line of the valve and the axis line of the tank may be substantially parallel to or coincident with each other.
According to the configuration, the valve can be made to have an easy self cleaning structure. For example, when the valve has the above-mentioned configuration, the contamination such as powdery abrasion dust generated at the time of movement of the valve body may be discharged to the secondary side by the flow of fluid from the primary side to the secondary side.
On the other hand, the valve generally tends to increase in a length thereof in the axial direction as a whole. Accordingly, when the axis line of the valve and the axis line of the tank are coincident with each other, the total length of the valve and the tank is apt to be elongated.
Accordingly, from a viewpoint of relatively reducing the total length of the valve and the tank, the valve may be located outside the body of the tank and the axis line of the valve and the axis line of the tank may be substantially orthogonal to each other.
According to the configuration, the installation space occupied by installing of the valve and the tank cannot be extremely large.
In a preferred embodiment of the present invention, the tank may be provided with a main stop valve independent from the above-said valve may be provided for the tank. The main stop valve may be located at the primary side of the above-described valve.
According to the configuration, it is possible to suppress the fluid pressure acting on the valve by closing the main stop valve. It is also possible to accomplish fail safe of the entire system of the tank.
More preferably, the main stop valve may be located more inside the tank than the mouthpiece portion of the tank and the valve may be located outside the body of the tank.
In order to accomplish the above object, a valve controller according to the invention accomplishes the duty control of the above-mentioned valve of the invention.
With the configuration, it is possible to adequately duty-control the valve and thus to minutely adjust the flow rate of the fluid from the tank to the outside.
In order to achieve the afore-mentioned object, a fuel cell system according to the invention includes the above-mentioned valve; the tank; and a fuel cell supplied with oxidant gas and fuel gas. The fluid in the tank is fuel gas.
With the configuration, it is possible to supply the fuel gas, the flow rate of which has been adjusted by the valve, to the fuel cell. Hence, it is possible to supply desired fuel gas from the tank with a high response property in correspondence with the amount of consumption of the fuel gas in the fuel cell.
According to another aspect of the present invention, there is provided a fuel cell system including: the above-mentioned valve; a tank capable of storing fuel gas; a fuel cell supplied with the fuel gas from the tank; and a main stop valve disposed on the tank so that the main stop valve is located at a primary side of the valve. The main stop valve is closed at the time of stopping of the operation of the fuel cell system.
Hereinafter, a fuel cell system having a valve according to embodiments of the invention will be described with reference to the accompanying drawings. In the fuel cell system, a valve under duty control is disposed on a tank to adjust a flow rate of fuel gas from the tank. In the following description, an injector is described as an example of the valve under duty control.
As shown in
The fuel cell 2 is of, for example, a solid polymer electrolyte type and has a stack structure in which plural unit cells are stacked. The unit cell of the fuel cell 2 has an air electrode on one surface of the electrolyte formed of an ion exchange membrane and a fuel electrode on the other surface. The unit cell has a pair of separators with the air electrode and the fuel electrode interposed therebetween. The fuel gas is supplied to a fuel gas flow channel of one separator and the oxidant gas is supplied to an oxidant gas flow channel of the other separator. The fuel cell 2 generates electric power with the gas supply.
The oxidant gas piping system 3 includes a supply passage 11 in which the oxidant gas supplied to the fuel cell 2 flows and a discharge passage 12 in which oxidant-off gas discharged from the fuel cell 2 flows. The supply passage 11 is provided with a compressor 14 blowing in the oxidant gas through a filter 13 and a humidifier 15 humidifying the oxidant gas pressurized and transported by the compressor 14. The oxidant-off gas flowing in the discharge passage 12 passes through a back-pressure control valve 16, is exchanged in humidity by the humidifier 15, and then is discharged as waste gas from the system to atmospheric air.
The fuel gas piping system 4 includes a hydrogen tank 21 as a fuel source, a supply passage 22 in which the hydrogen gas supplied from the hydrogen tank 21 to the fuel cell 2 flows, a circulation passage 23 for returning hydrogen-off gas (fuel-off gas) discharged from the fuel cell 2 to a merging point A of the supply passage 22, a pump 24 feeding the hydrogen-off gas in the circulation passage 23 under pressure to the supply passage 22, and a discharge passage 25 branched from the circulation passage 23.
The hydrogen tank 21 is configured to store the hydrogen gas of 35 MPa or 70 MPa. When a main stop valve 26 for the hydrogen tank 21 is opened, the hydrogen gas flows in the supply-passage 22. Thereafter, the hydrogen gas is adjusted in flow rate and pressure by the injector 29, is reduced in pressure to, for example, 200 kPa by a pressure reducing valve including a mechanical regulator valve 27, and is then supplied to the fuel cell 2. The main stop valve 26 and the injector 29 are fitted to a valve assembly 30 indicated by a dotted frame line in
A shutoff valve 28 is disposed upstream the merging point A of the supply passage 22. A circulation system of the hydrogen gas includes a downstream flow channel downstream the merging point A of the supply passage 22, a fuel gas flow channel formed in the separator of the fuel cell 2, and the circulation passage 23, which sequentially communicate with each other. A purge valve 33 on the discharge passage 25 is properly opened or closed during the operation of the fuel cell system 1, whereby impurities in the hydrogen-off gas is discharged to a hydrogen diluter not shown along with the hydrogen-off gas. The impurity concentration of the hydrogen-off gas in the circulation passage 23 is lowered with the opening of the purge valve 33, and the hydrogen concentration of the circulating hydrogen-off gas is enhanced.
The controller 7 is constituted as a micro computer having a CPU, an ROM, and an RAM therein. The CPU performs desired calculations in accordance with a control program to perform various processes or control such as a flow rate control of the injector 29. The ROM stores a control program or control data to be processed by the CPU. The RAM is used as various operation areas for the control process. The controller 7 receives detection signals of various pressure sensors or temperature sensors used in gas systems (3, 4) or a coolant system not shown and outputs control signals to the elements. As described later, the controller 7 serves as a valve controller for controlling the injector 29 by a duty control.
First, the hydrogen tank 21 is described.
The hydrogen tank 21 includes a tank body 101 forming a body of the hydrogen tank 21 and having a closed cylindrical shape and a mouthpiece portion 102 located at an end in the longitudinal direction of the tank body 101. The inside of the tank body 101 serves as a reservoir space 104 storing the hydrogen gas with a high pressure. The tank body 2 has a two-layered structure of an inside resin liner 107 having a gas barrier property and a shell 108 covering the outside of the resin liner 107. The shell 108 is formed of FRP.
The mouthpiece portion 102 (mouth portion) is formed of metal such as stainless and is disposed at the center of one spherical end wall of the tank body 101. The valve assembly 30 can be screwed into the mouthpiece portion 102 by the use of an internal thread formed in the inner circumferential surface of the mouthpiece portion 102.
The valve assembly 30 extends to the inside and the outside of the hydrogen tank 21 and forms a gas discharge section of the hydrogen tank 21. The valve assembly 30 has, for example, a single housing 300, and the main stop valve 26 and the injector 29 are fitted in series to the housing 300. In this embodiment, the main stop valve 26 is disposed in a first area 301 of the housing 300 inserted into the hydrogen tank 21, and the injector 29 is disposed in a second area 302 exposed from the hydrogen tank 21. The housing 300 is formed of metal such as SUS or aluminum.
Although the injector 29 and the main stop valve 26 as chief elements of the invention are mainly shown in
An in-valve flow channel 310 allowing the reservoir space 104 to communicate with the outside supply passage 22 is formed in the housing 300. The in-valve flow channel 310 includes a first flow channel 311, a second flow channel 312, and a third channel 313 sequentially from the reservoir space 104. The space between the first flow channel 311 and the second flow channel 312 is opened or closed by the main stop valve 26. The second flow channel 312 forms a primary flow channel of the injector 29. The third flow channel 313 forms a secondary flow channel of the injector 29 and is connected to the outside supply passage 22.
The main stop valve 26 (on-off valve) serves as a source valve for the hydrogen tank 21 and blocks the flow of fluid (hydrogen gas) from, the hydrogen tank 21 to the supply passage 22. The main stop valve 26 is constituted as an electromagnetic shutoff valve. The main stop valve 26 shuts off the in-valve flow channel 310, for example, when a valve rod 321 (mobile) goes in the axial direction by the excitation of a solenoid and a valve body 322 at an end of the valve rod 321 comes into contact with a valve seat 323. On the other hand, when the valve rod 321 goes back in the axial direction by the demagnetization of the solenoid and the valve body 322 breaks contact with the valve seat 323, the hydrogen gas is allowed to flow out of the reservoir space 104. The axial direction X-X of the valve rode 321 and the valve body 322 is equal to the axial direction of the hydrogen tank 21. The axial direction of the main stop valve 26 means the movement direction of the valve body 322 and corresponds to the axial direction X-X of the valve body 322 in this case.
The injector 29 is located outside the outer circumferential surface of the tank body 101 and is electrically connected to the controller 7. The injector 29 is an electromagnetic on-off valve that can adjust the flow rate or the pressure of the hydrogen gas by driving the valve body 401 at a predetermined driving period using an electromagnetic driving power to move the valve body away from the valve seat 402. The injector 29 can control the driving period of the valve body 401 to a high-response region and thus has higher response property than that of a mechanical pressure regulating valve.
The injector 29 has a flow rate adjusting mechanism 290 that can adjust the flow rate and the pressure of the hydrogen gas to the secondary side. The flow rate adjusting mechanism 290 roughly includes a main valve portion 410 and a solenoid portion 420. The main valve portion 410 and the solenoid portion 420 are disposed in the second area 302 of the housing 300 and adjust the flow rate of the hydrogen gas from the hydrogen tank 21 by the duty control.
The main valve portion 410 includes the valve body 401 and the valve seat 402. The valve body 401 is of a poppet type and is formed of metal. The axial direction Y-Y of the valve body 401 is perpendicular to the axial direction X-X of the hydrogen tank 21. The axial direction of the injector 26 means the movement direction of the valve body 401 and corresponds to the axial direction Y-Y of the valve body 401 in this case.
The valve seat 402 is formed of an annular resin member having a seal property and a pressure-resistant property and has an elastic modulus higher than the housing 300 (base member). The center of the valve seat 402 is opened and serves as a jet hole 404 jetting the hydrogen gas to the secondary side. The opening area of the jet hole 404 changes depending on the position of the valve-body 401 in the axial direction. When the valve body 401 comes into contact with the valve seat 402, the opening area of the jet hole 404 is zero and the outflow of the hydrogen gas to the secondary side is prevented. As described above, since the valve seat 402 has an elastic property, the valve body 401 can be made to come closely into contact with the valve seat 402, thereby preventing the outflow of the hydrogen gas to the secondary side with a high sealing property.
The solenoid portion 420 can have a variety of basic structures such as an I plunger type and is for a so-called flat panel type in this embodiment. Specifically, the solenoid portion 420 includes a coil 421, a core 422, and a plunger 423 having a flat panel shape formed integrally with the valve body 401. A gap exists between the core 422 and the plunger 423, and a spring 425 is disposed coaxial (in the Y-Y direction) with the valve body 401. The spring 425 biases the valve body 401 to the valve seat 402.
In the injector 29, the coil 421 is electrified, and then the core 422 is magnetized and attracts the plunger 423 and the valve body 401. Accordingly, the valve body 401 moves in a direction in which it gets apart from the valve seat 402 against the spring 425. On the contrary, when the electrification of the coil 421 is stopped; that is, when the solenoid portion 420 is demagnetized, the valve body 401 moves by the spring force of the spring 425 in a direction in which it gets contact with the valve seat 402. The current supplied to the coil 421 is pulse-like excitation current.
In this way, the injector 29 is configured to change the opening time (ON time) or the opening area of the jet hole 404 by two steps, by multiple steps, continuously (by no step), or linearly, by turning on or off the pulse-like current supplied to the coil 421. The gas jet time and timing of the jet hole 404 are controlled by the control signals output from the controller 7, whereby the injector 29 adjusts the flow rate and the pressure of the hydrogen gas with high precision. The duty control method of changing the duty ratio of the pulse-like excitation current is used as the control method of the injector 29. Here, the duty ratio is obtained by dividing the ON time of the pulse-like excitation current by the switching period as the sum of the ON time and the OFF time of the pulse-like excitation current. By changing the duty ratio, the injector 29 can adjust a secondary pressure to any pressure of 0 to a primary pressure (tank inside pressure).
As shown in
According to the above-mentioned embodiment, the injector 29 is disposed on the hydrogen tank 21, and it is possible to adjust the flow rate and the pressure of the hydrogen gas by the use of the injector 29 when the hydrogen gas is supplied from the hydrogen tank 21 to the supply passage 22. Accordingly, it is possible to adjust the flow rate (supply flow rate) of the hydrogen gas from the hydrogen tank 21 to the fuel cell 2 with higher precision than that of the case where a mechanical pressure regulating valve is disposed on the hydrogen tank 21. In addition, since the injector 29 has higher response property than the mechanical pressure regulating valve, it is possible to supply the fuel cell 2 with the hydrogen gas at a flow rate based on the electricity generated by the fuel cell 2, the consumption of the hydrogen gas, or the operation state.
The injector 29 can block the discharge of the hydrogen gas to the secondary side and the injector 29 can be made to serves as a tank source valve. Particularly, since the hydrogen gas pressure (tank inside pressure) of the primary side acts on the surface of the plunger 423 opposed to the core 422 at the time of blocking, a force in the closing direction acts on the valve body 401 through the plunger 423. Accordingly, it is possible to enhance the degree of close contact between the valve body 401 and the valve seat 402 and thus to enhance the blocking property of the flow channel in the injector 29.
On the other hand, in this embodiment, the main stop valve 26 as the tank source valve is disposed on the primary side of the injector 29. Accordingly, by closing the main stop valve 26 when stopping the fuel cell system 1 (at the time of stop of the hydrogen gas supply), it is possible to prevent the tank inside pressure from acting directly on the injector 29. Even when the blocking property of the injector 29 is deteriorated, it is possible to block the discharge of the hydrogen gas from the hydrogen tank 21 by the use of the main stop valve 26, thereby properly accomplishing fail safe.
In addition, the following advantages are obtained in view of arrangement of the injector 29.
That is, since the injector 29 is disposed outside the hydrogen tank 21, it is possible to enhance the treatment or repair property of the injector 29. Since the heat exchange of the injector 29 with external air is facilitated, it is possible to suppress the influence of a decrease in temperature of the hydrogen tank 21 at the time of discharging gas.
Moreover, since the axial direction Y-Y of the injector 29 is perpendicular to the axial direction X-X of the hydrogen tank 21, it is possible to relatively reduce the total length of the structure in which the valve assembly 30 is disposed on the hydrogen tank 21. Accordingly, it is possible to reduce the size as a whole and to reduce the installation space for the hydrogen tank 21. In view of the limited installation space, the hydrogen tank 21 can be relatively enhanced in the longitudinal direction, thereby enhancing the storage capacity of the hydrogen gas. The axial direction Y-Y of the injector 29 may be made to cross the axial direction X-X of the hydrogen tank 21.
Next, an injector 29 (valve) according to a second embodiment of the invention will be described with reference to
The injector 29 includes a main valve portion 410, a solenoid portion 420, and a handle portion 430. The portions 410, 420, and 430 are disposed on the first area 301 of the valve assembly 30 sequentially along the axial direction X-X of the hydrogen tank 21. That is, in this embodiment, the axial direction of the injector 29 corresponding to the axial direction of the valve body 401 is equal to the axial direction X-X of the hydrogen tank 21.
An annular flow channel or plural flow channels 451 are formed through the handle portion 430. The flow channel 451 extends in the axial direction X-X and communicates with the flow channel 453 in the housing 300. The flow channel 451 extends in the axial direction X-X so that the hydrogen gas flows in the outer circumference of the solenoid portion 420, and communicates with a flow channel 455 on the secondary side of the injector 29. The flow channel 455 is formed in the housing 300 and communicates with the supply passage 22. Accordingly, the hydrogen gas in the reservoir space 104 flows sequentially through the flow channel 451, the flow channel 453, the jet hole 404, and the flow channel 455 in the injector 29 and then flows to the supply passage 22.
The second embodiment is more advantageous than the first embodiment, in that the injector 29 can easily make itself clean due to the injector 29 disposed coaxial with the hydrogen tank 21.
Specifically, contamination such as abrasion dust generated at the time of movement of the valve body 401 in the axial direction can be discharged to the flow channel 455 along with the hydrogen gas flowing in the flow channel 453. Accordingly, the contamination does not stay around the solenoid portion 420 of the injector 29 and thus the injector 29 can make itself clean with a simple structure. The self cleaning effect is advantageous particularly when the outer circumferential surface of the plunger 423 or the outer circumferential surface of the valve body 401 slides on the inside wall of the housing 300. Note that
In a modified example of this embodiment, the axial direction of the injector 29 may not be matched with the axial direction X-X of the hydrogen tank 21 and, for example, both directions may be parallel to each other. In this case, the above-mentioned advantages can be obtained. Note that although the main stop valve 26 has been omitted from the valve assembly 30, the main stop valve 26 may be disposed on the primary side of the injector 29.
The injectors 29 described in the first and second embodiments can be considered as a pressure regulating valve (pressure reducing valve, regulator), since the gas pressure to the secondary side can be adjusted.
The above-mentioned fuel cell system 1 according to the invention can be mounted on a two-wheel or four-wheel vehicle, a train, an air plane, a ship, a robot, and other mobile bodies. The fuel cell system 1 may be stationary, or may be built in a cogeneration system. In addition, the tank having the injector 29 disposed thereon may be a hydrogen storing alloy tank or may store other hydrocarbon fuel gas. For example, the tank may store compressed natural gas, for example, by 20 MPa, and the kind of the stored fluid is not limited to gas or liquid.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-060128 | Mar 2006 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2007/052438 | 2/6/2007 | WO | 00 | 7/31/2008 |
