JP2005276697A - Gas pump for fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas pump making stable power generation possible by efficiently supplying gas of a flow rate of small pulsation in a fuel cell system. <P>SOLUTION: Opposite direction magnetic force alternately acts to a permanent magnet 28 by an electromagnet 29 to reciprocate a driving rod 27, a moving body 25 fixed to both ends of the driving rod is moved in front and the rear to alternately increase and decrease the volume of a pair of pump chambers 24. When the volume of one pump chamber is increased and gas flows in the pump chamber through an admission valve from a suction passage, the volume of the other pump chamber is decreased, gas is discharged to a discharge passage 36, through a delivery valve 33, and since this action is continuously repeated, gas is continuously supplied from a pair of pump chambers to the discharge passage, and joined in the discharge passage to relieve flow rate variation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gas pump used in a fuel cell system that generates a reformed gas from supplied reforming fuel gas and water vapor and supplies the reformed gas to a fuel cell.

  In a fuel cell system, a reforming fuel gas (for example, a hydrocarbon fuel gas such as natural gas or LP gas) supplied by controlling the flow rate with a gas pump and pure water are flow-controlled and supplied to a water evaporator. The generated steam is mixed and supplied to the reforming section to generate reformed gas. Then, carbon monoxide is reduced from the reformed gas to generate a so-called hydrogen-rich reformed gas, and this reformed gas is supplied to the fuel cell. The fuel cell generates power by a chemical reaction between hydrogen in the supplied reformed gas and oxygen in the air.

In Patent Document 1, a piston that is reciprocated by an attractive force of an electromagnet and a resilient force of a return spring is fitted into a cylinder to define a pump chamber at the front of the cylinder, and a suction valve is provided in the pump chamber by retreating the piston. There is disclosed a gas pump that sucks gas through and discharges gas from a pump chamber through a discharge valve by advance of a piston.
JP 2003-021061 A (second page, FIG. 5) JP-A-8-222253 JP 2002-303143 A

   When the gas pump described above is used as, for example, a gas pump that supplies reforming fuel gas to a reforming device of a fuel cell system, gas is discharged when the piston moves forward, but gas is discharged when the piston moves backward. As shown in FIG. 6, the flow rate of the reforming fuel gas supplied to the reforming device is intermittently greatly changed and does not flow uniformly, so that the amount of reformed gas generated changes, The amount of hydrogen supplied to the fuel cell changed, and it was not possible to generate power efficiently. Furthermore, since gas is intermittently discharged only when the piston moves forward, there is a problem that pump efficiency is poor and power consumption is increased.

   The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a gas pump that efficiently supplies a gas with a small pulsation in a fuel cell system and enables stable power generation.

  In order to solve the above problems, the structural feature of the invention according to claim 1 is that a fuel cell system that generates reformed gas from water vapor and reforming fuel gas and supplies the reformed gas to the fuel cell. In the gas pump used in the present invention, a movable body that forms two or more pump chambers in the housing and increases or decreases the volume of the pump chamber is housed in the housing, and a suction valve chamber and a pump valve corresponding to each of the pump chambers individually. A discharge valve chamber is provided, a suction valve that allows only the flow from the suction valve chamber to the pump chamber is provided between each suction valve chamber and the corresponding pump chamber, and between each pump chamber and the corresponding discharge valve chamber. A discharge valve that allows only the flow from the pump chamber to the discharge valve chamber is provided, a suction path that communicates with each suction valve chamber and a discharge path that communicates with each discharge valve chamber are formed, and the suction path is drilled in the housing Communication with the suction port Wherein the discharge passage communicates with the discharge port which is formed in said housing, said is to periodically reciprocate with a predetermined phase difference with each other to the movable member.

  The structural feature of the invention according to claim 2 is that, in claim 1, the pump chambers are formed at both ends in the axial direction of the housing, and the movable body forms an inner wall of each pump chamber and the axis of the housing. The suction valve chamber and the discharge valve chamber are provided at both ends of the housing, the suction passage and the discharge passage are formed in the housing in the axial direction, and the movable bodies are mutually connected with a predetermined phase difference. In order to reciprocate periodically, a drive rod connected to each movable body at both ends is provided in a central hole formed in the housing between the pump chambers. Permanent magnets are provided with both poles aligned in the axial direction, and an electromagnet for reciprocating the drive rod in the axial direction by alternately applying a magnetic force in the opposite direction to the permanent magnet is fixed to the central hole.

  According to a third aspect of the present invention, in the first or second aspect of the invention, in order to absorb the pulsation of the gas pressure discharged from each pump chamber, the volume of the discharge path is increased and the discharge retention chamber It is that.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the discharge port is formed in the housing at a central portion of the discharge path in a direction perpendicular to the axial direction of the discharge path. In addition, it acts as a throttle for the gas discharged from each pump chamber.

  The structural feature of the invention according to claim 5 is that a pair of shielding plates are provided on both sides of the inlet portion of the discharge port in order to prevent pressure from directly propagating from each discharge valve chamber to the discharge port. That is.

  In the invention according to claim 1 configured as described above, the movable bodies are periodically reciprocated with a predetermined phase difference, and the volumes of the pump chambers are increased or decreased with a predetermined phase difference. When the volume of the pump chamber increases and gas flows into the pump chamber from the suction path through the suction valve, the volume of the other pump chamber decreases and the gas is discharged to the discharge path through the discharge valve This is repeated continuously, and gas is continuously supplied from the pump chambers to the discharge passages, and merged in the discharge passages to reduce fluctuations in flow rate. Thus, for example, when the reforming fuel gas is supplied to the reforming unit by the gas pump, the flow rate of the reforming fuel gas becomes continuous, the pulsation is suppressed, and the reformed gas can be generated continuously. In addition, the amount of hydrogen supplied to the fuel cell can be stabilized and power can be generated efficiently. Further, since the pulsation of the flow rate of the discharged gas is suppressed, the detection accuracy is improved when detecting the flow rate.

   In the invention according to claim 2 configured as described above, the magnetic force in the opposite direction is alternately applied to the permanent magnet by the electromagnet, so that the drive rod is reciprocated, and the movable body fixed to both ends of the drive rod is reciprocated. Thus, the volume of each pump chamber is increased or decreased alternately. When the volume of one pump chamber increases and gas flows into the pump chamber from the suction passage through the suction valve, the volume of the other pump chamber decreases and the gas is discharged to the discharge passage through the discharge valve. Therefore, the gas is continuously supplied from the pump chambers to the discharge passage, and merged in the discharge passage to reduce the flow rate fluctuation. Thus, the same effect as that of the invention according to claim 1 can be obtained, and the gas is discharged during any reciprocation of the operating rod, so that the pump efficiency can be improved and the power consumption can be reduced.

  In the invention according to claim 3 configured as described above, since the gas discharged from each pump chamber is once retained in the discharge retention chamber, the pulsation of the flow rate of the gas discharged from each pump chamber can be simplified. It can absorb efficiently by the configuration.

  In the invention according to claim 4 configured as described above, since the discharge port is formed in the housing at the central portion of the discharge path in a direction perpendicular to the axial direction of the discharge path, the gas pressure from each discharge valve chamber is Is directly transmitted to the outside from the discharge port. Furthermore, since the discharge port acts as a throttle for the gas discharged from the pair of pump chambers, it is possible to further suppress the pulsation of the flow rate of the gas sent from the discharge residence chamber through the discharge port.

   In the invention according to claim 5 configured as described above, since the pressure propagated from each discharge valve chamber is shielded by each shielding plate and prevented from directly propagating to the discharge port, the pressure is sent through the discharge port. The pulsation of the gas flow rate can be further suppressed.

  Hereinafter, a first embodiment of a gas pump for a fuel cell system according to the present invention will be described. As shown in FIG. 1, the fuel cell system includes a fuel cell 11 and a reformer 12 that generates and supplies hydrogen gas necessary for the fuel cell 11. A reformed gas is supplied from the reformer 12 to the fuel electrode of the fuel cell 11, and air from the outside is supplied to the air electrode of the fuel cell 11 by an air pump. The gas and oxygen gas in the air react to generate power.

  The reformer 12 includes a reformer 13 that reforms a hydrocarbon-based reforming fuel gas such as natural gas or LPG into hydrogen gas, and water that evaporates pure water supplied from a water pump to generate water vapor. The evaporator 15, the cooling unit 16 stacked below the reforming unit 13, the carbon monoxide contained in the reformed gas that is stacked below the cooling unit 16 and generated by the reforming unit 13 and cooled by the cooling unit 16. A carbon monoxide shift reaction unit (hereinafter referred to as a CO shift unit) 17 to be removed, and a carbon cell contained in the reformed gas sent from the CO shift unit 17 connected to the CO shift unit 17 are further removed to form a fuel cell. 11, a carbon monoxide selective oxidation unit (hereinafter referred to as a CO purification unit) 18 that is supplied to 11.

  The reforming unit 13 includes a reaction chamber 19 filled with a catalyst, a heating chamber 20 that surrounds the upper and outer periphery of the reaction chamber 19 and heats the reaction chamber 19, and a combustion fuel gas sent by a gas pump 22. Combustion air sent by an air pump is mixed and burned, and a burner 21 that supplies high-temperature combustion gas to the heating chamber 20 is configured. The reforming fuel gas pumped by the gas pump 22 is mixed with the steam generated by the water evaporator 15, preheated by the cooling unit 16 and supplied to the reaction chamber 19, and the reforming fuel gas and steam are heated. The reformed gas is generated by the steam reforming reaction and the carbon monoxide shift reaction by the catalyst.

   FIG. 2 is a diagram showing the configuration of the gas pump 22. The gas pump 22 is formed with a pair of pump chambers 24 at both axial ends of the housing 23. A diaphragm 25 is hermetically fixed inside each pump chamber 24 and forms an inner wall of each pump chamber 24. Each diaphragm 25 functions as a movable body that is accommodated in the housing 23 and moves in the axial direction to increase or decrease the volume of each pump chamber 24. A central hole 26 is formed in the housing 23 between the pair of pump chambers 24, and both ends of a drive rod 27 disposed in the central hole 26 are airtightly connected to the central portion of each diaphragm 25. A permanent magnet 28 is fixed to the central portion of the drive rod 27 with the north and south poles aligned in the axial direction. A pair of electromagnets 29 are fixed in the central hole 26 so as to face both poles of the permanent magnet 28, and the magnetic poles of the respective electromagnets 29 respectively facing both poles of the permanent magnet 28 are alternately cut to the same N pole or S pole. The direction of the current flowing through the coil of each electromagnet is controlled to be switched so that the opposite magnetic force acts alternately from the pair of electromagnets 29 to the permanent magnet 28, the drive rod 27 is reciprocated in the axial direction, and each diaphragm 25. Are reciprocated periodically with a predetermined phase difference of 180 degrees.

   Corresponding to each pump chamber 41 individually, a suction valve chamber 30 and a discharge valve chamber 31 are formed at both ends of the housing 23 across the outer wall of each pump chamber 24. Between each suction valve chamber 30 and the pump chamber 24, a suction valve 32 that allows only a flow from the suction valve chamber 30 toward the pump chamber 24 is provided, and between each pump chamber 24 and the discharge valve chamber 31. Is provided with a discharge valve 33 that allows only a flow from the pump chamber 24 toward the discharge valve chamber 31. Each suction valve chamber 30 communicates with a suction passage 34 formed in the housing 23 in the axial direction. The suction passage 34 is formed in the central portion of the suction passage 34 in the axial direction so as to be opened in the direction perpendicular to the axial direction. A suction port 35 is connected. A diversion projection 39 is formed in the intake passage 34 so as to face the opening of the intake port 35, and the gas sucked from the intake port 35 flows smoothly toward the intake valve chambers 30 on both sides by the diversion projection 39. Change and divert.

   Each discharge valve chamber 31 is communicated by a discharge passage 36 formed in the housing 23 in the axial direction. The discharge passage 36 has an axial central portion in the axial direction of the housing 23 at a central portion between the pair of pump chambers 24. The discharge port 37 is formed in a direction perpendicular to the opening and opened to the outside. The discharge path 36 is formed with a large volume and serves as a discharge retention chamber in order to absorb the pulsation of the gas pressure discharged from the pair of pump chambers 24. The discharge port 37 is formed in a cross-sectional area that acts as a throttle for the gas discharged from the pair of pump chambers 24. On both sides of the inlet portion of the discharge port 37 in the discharge retention chamber 34, the pressure propagated in the axial direction from each discharge valve chamber 31 toward the discharge port 37 is reflected to the opposite side of the discharge port 37 at right angles to the axial direction. A pair of shielding plates 38 are provided to prevent the pressure from propagating directly to the discharge port 37.

   Next, the operation of the above embodiment will be described. In the reforming unit 13, combustion fuel gas and combustion air are supplied to the burner 21, and combustion gas generated by burning the combustion fuel gas flows through the heating chamber 20 to heat the catalyst in the reaction chamber 19. The reforming fuel gas sent from the gas pump 22 and the water vapor generated by the water evaporator 15 are mixed and sent to the cooling unit 16 to exchange heat with the high-temperature reformed gas reformed by the reforming unit 13. Then, it is preheated and sent to the reaction chamber 19 of the reforming section 13. In the reaction chamber 19, a reformed gas is generated by a steam reforming reaction and a carbon monoxide shift reaction using a catalyst in which steam and reforming fuel gas are heated. The reformed gas generated in the reforming unit 13 is supplied to the fuel cell 11 after the carbon monoxide gas is reduced in the CO shift unit 17 and the CO purification unit 18.

   In the gas pump 22, each of the electromagnets 29 is alternately arranged so that the opposing magnetic poles of the pair of electromagnets 29 respectively facing the N pole and the S pole of the permanent magnet 28 simultaneously become the N pole and then simultaneously become the S pole. Since the direction of the current supplied to the coil is alternately switched and controlled, when the opposing magnetic pole of each electromagnet 29 becomes the S pole, the N pole of the permanent magnet 28 is attracted to the opposing magnetic pole, and the S pole is repelled. On the contrary, when each counter magnetic pole becomes N pole, the permanent magnet 28 is attracted to the counter magnetic pole, and the N pole is repelled and moved to the right. Accordingly, the drive rod 27 is reciprocated, the diaphragms 25 are reciprocated in the axial direction, and when one of the pair of pump chambers 24 expands, the other contracts repeatedly. In the expanding pump chamber 24, the discharge valve 33 is closed, the suction valve 32 is opened, and the reforming fuel gas is sucked into the pump chamber 24 from the suction valve chamber 30. The suction valve chamber 30 has a suction port 35 and a suction passage 34. The reforming fuel gas is replenished. In the contracting pump chamber 24, the suction valve 32 is closed, the discharge valve 33 is opened, and the reforming fuel gas is discharged from the pump chamber 24 to the discharge valve chamber 31. As shown in FIG. 3 (a), the reforming fuel gas is discharged from one pump chamber 24 to the discharge valve chambers 31 when the drive rod 27 moves forward and from the other pump chamber 24 when the drive rod 27 moves backward. The chamber 36 is continuously supplied. Since the reforming fuel gas discharged from the pair of pump chambers 24 is temporarily retained in the discharge retention chamber 36 having a large volume, in combination with the throttle action of the discharge port 37 as shown in FIG. The pulsation of the gas pressure of the reforming fuel gas discharged from the pair of pump chambers 24 is absorbed, and the flow rate of the reforming fuel gas is leveled. As the reforming fuel gas is discharged from each pump chamber 24, the pressure propagated from each discharge valve chamber 31 is shielded by each shielding plate 38 and is not directly propagated to the discharge port 37. The pulsation of the flow rate of the reforming fuel gas delivered to the reforming unit 13 is further suppressed.

   Next, a second embodiment of the fuel cell system gas pump will be described with reference to FIGS. A pair of pump chambers 41 are formed at both ends in the longitudinal direction of the housing 40, and a diaphragm 42 is airtightly fixed below each pump chamber 41 to form a lower wall of each pump chamber 41. Each diaphragm 42 functions as a movable body that is accommodated in the housing 40 and moves in the axial direction to increase or decrease the volume of each pump chamber 41. A crank chamber 43 is formed in the housing 40 below each diaphragm 42, and each upper end of a drive rod 44 disposed in the crank chamber 43 on both sides is airtightly connected to the center of each diaphragm 42. A motor 45 is fixed between the crank chambers 43 on both sides, and the rotation shafts 46 projecting on both sides in the longitudinal direction of the motor 45 extend into the crank chambers 43 on both sides, via the drive rods 44 and the crank mechanisms 47. Are connected to each other. The rotation phase difference between the crank mechanisms 47 is 180 degrees, the rotation of the rotating shaft 46 of the motor 45 is converted into the reciprocating motion of the drive rod 44 by the crank mechanism 47, and the diaphragms 42 have a predetermined phase difference of 180 degrees from each other. It is reciprocated periodically.

   Corresponding to each pump chamber 41 individually, a suction valve chamber 48 and a discharge valve chamber 49 are formed at both upper ends in the longitudinal direction of the housing 23 with the upper wall of each pump chamber 41 interposed therebetween. Between each suction valve chamber 48 and the pump chamber 41, a suction valve 50 that allows only a flow from the suction valve chamber 48 toward the pump chamber 41 is provided, and between each pump chamber 41 and the discharge valve chamber 49. Is provided with a discharge valve 51 that allows only a flow from the pump chamber 41 toward the discharge valve chamber 49. Each suction valve chamber 48 is communicated with a suction passage 52 formed in the longitudinal direction at the upper end portion of the housing 40, and is formed in the housing 40 at a center portion in the longitudinal direction in a direction perpendicular to the longitudinal direction. A suction port 53 that opens to the outside communicates. A diversion projection 54 is formed in the intake passage 52 so as to face the opening of the intake port 53, and the gas sucked from the intake port 53 smoothly flows toward the intake valve chambers 48 on both sides by the diversion projection 54. Change and divert.

   Each discharge valve chamber 49 is communicated with a discharge passage 55 formed in the housing 40 in the axial direction, and the discharge passage 55 has a longitudinal central portion in the longitudinal direction of the housing 40 at a central portion between the pair of pump chambers 41. A discharge port 56 is formed in a direction perpendicular to the opening and opened to the outside. The discharge path 55 is formed with a large volume and serves as a discharge retention chamber in order to absorb the pulsation of the gas pressure discharged from the pair of pump chambers 41. The discharge port 56 is formed in a cross-sectional area that acts as a throttle for the gas discharged from the pair of pump chambers 41. On both sides of the inlet portion of the discharge port 56 in the discharge staying chamber 55, the pressure propagated in the longitudinal direction from each discharge valve chamber 49 toward the discharge port 56 is reflected to the opposite side of the discharge port 56 at right angles to the longitudinal direction. A pair of shielding plates 57 are provided to prevent the pressure from directly propagating to the discharge port 56.

   In the gas pump 58 according to the second embodiment, when the motor 45 is started and the rotating shaft 46 is rotated, the drive rod 44 is reciprocated via the crank mechanism 47, and each diaphragm 42 is reciprocated with a phase difference of 180 degrees. It is moved, and when one of the pair of pump chambers 41 expands, the other contracts repeatedly. In the expanding pump chamber 41, the discharge valve 51 is closed, the suction valve 52 is opened, and the reforming fuel gas is sucked into the pump chamber 41 from the suction valve chamber 48. The suction valve chamber 48 has a suction port 53 and a suction passage 52. The reforming fuel gas is replenished. In the contracting pump chamber 41, the suction valve 50 is closed, the discharge valve 51 is opened, and the reforming fuel gas is discharged from the pump chamber 41 to the discharge valve chamber 49. At this time, similarly to the gas pump 22 according to the first embodiment, pulsation of the flow rate of the reforming fuel gas that is sent through the discharge port 56 and delivered to the reforming unit 13 is suppressed.

   In the above embodiment, the two pump chambers formed in the housing are alternately expanded and contracted with a phase difference of 180 degrees. However, two or more pump chambers are formed in the housing, and the volume of each pump chamber is increased or decreased. Each movable body to be moved may be reciprocated periodically with a predetermined phase difference of an angle obtained by dividing 360 degrees by the number of pump chambers, for example.

   In the above embodiment, the gas pump for the fuel cell system is used as the gas pump 22 for sending the reforming fuel gas to the reforming unit 13, but the air pump supplies air to the air electrode or the burner 21 of the fuel cell 11. Alternatively, it may be used in a gas pump or the like that supplies combustion fuel gas to the burner 21.

The schematic diagram showing the outline of the fuel cell system provided with the gas pump concerning the embodiment of the present invention. Sectional drawing of the gas pump for this fuel cell system. The figure which shows the discharge flow volume of the gas pump for this fuel cell system. Sectional drawing of the gas pump which concerns on 2nd Embodiment. Sectional drawing cut | disconnected along line 5-5 of FIG. The figure which shows the discharge flow volume of the conventional gas pump.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Fuel cell, 12 ... Reformer, 13 ... Reforming part, 15 ... Water evaporator, 16 ... Cooling part, 17 ... Carbon monoxide shift reaction part (CO shift part), 18 ... Carbon monoxide selective oxidation part (CO purification unit), 19 ... reaction chamber, 20 ... heating chamber, 21 ... burner, 22, 58 ... gas pump, 23, 40 ... housing, 24, 41 ... pump chamber, 25, 42 ... diaphragm (movable body), 26 ... central hole, 27, 44 ... drive rod, 28 ... permanent magnet, 29 ... electromagnet, 30, 48 ... suction valve chamber, 31, 49 ... discharge valve chamber, 32, 50 ... suction valve, 33, 51 ... discharge valve, 34, 52 ... suction path, 35, 53 ... suction port, 36, 55 ... discharge path (discharge staying chamber), 37, 56 ... discharge port, 38, 57 ... shielding plate, 43 ... crank chamber, 45 ... motor, 47 ... Crank mechanism.

Claims (5)

In a gas pump used in a fuel cell system that generates reformed gas from steam and reforming fuel gas and supplies the reformed gas to a fuel cell,
Two or more pump chambers are formed in the housing, and a movable body for increasing or decreasing the volume of the pump chamber is accommodated in the housing, and a suction valve chamber and a discharge valve chamber are provided corresponding to each of the pump chambers. A suction valve that allows only the flow from the suction valve chamber to the pump chamber is provided between each suction valve chamber and the corresponding pump chamber, and the discharge valve from the pump chamber is disposed between each pump chamber and the corresponding discharge valve chamber. A discharge valve that allows only the flow toward the chamber is provided, and a suction passage that communicates with each suction valve chamber and a discharge passage that communicates with each discharge valve chamber are formed, and the suction passage communicates with a suction port formed in the housing. A gas pump for a fuel cell system, wherein the discharge passage is communicated with a discharge port formed in the housing, and the movable bodies are periodically reciprocated with a predetermined phase difference.   2. The pump chamber according to claim 1, wherein the pump chamber is formed at both axial ends of the housing, and the movable body is movable in the axial direction of the housing by forming an inner wall of each pump chamber. Chambers are provided at both ends of the housing, the suction passage and the discharge passage are formed in the housing in the axial direction, and the movable bodies are reciprocated periodically with a predetermined phase difference. A drive rod having both ends connected to the body is provided in a central hole formed in the housing between the pump chambers, and a permanent magnet is provided in the central portion of the drive rod with both poles aligned in the axial direction. A gas pump for a fuel cell system, wherein an electromagnet for reciprocating a drive rod in an axial direction by alternately applying a magnetic force in the opposite direction to the permanent magnet is fixed to the central hole.   The gas pump for a fuel cell system according to claim 1 or 2, wherein a volume of the discharge path is increased to form a discharge retention chamber in order to absorb pulsation of gas pressure discharged from each pump chamber.   4. The discharge port according to claim 1, wherein the discharge port is formed in the housing at a central portion of the discharge passage in a direction perpendicular to the axial direction of the discharge passage, and for the gas discharged from each pump chamber. A gas pump for a fuel cell system characterized by acting as a throttle.   5. The fuel cell system according to claim 4, wherein a pair of shielding plates are provided on both sides of the inlet portion of the discharge port in order to prevent pressure from directly propagating from each discharge valve chamber to the discharge port. Gas pump.

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