JP2007024015A - Hydrogen circulating pump and fuel cell system using hydrogen circulating pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen circulating pump which can prevent hydrogen concentration in a motor chamber from reaching the level of an explosive atmosphere and which can manufacture the motor chamber without considering tolerance with respect to hydrogen gas as well as a fuel cell system using the hydrogen circulating pump. <P>SOLUTION: The hydrogen circulating pump P which composes a hydrogen circulating pathway of the fuel cell system is provided with a pump section 31 which transfers hydrogen gas by rotation of a driving rotor 55 and a driven rotor 56 and a drive section 32 comprising an electric motor M installed inside a motor chamber 38 and rotatably driving a drive shaft 46. The hydrogen circulating pump P is also provided with a lip seal 48 which restrains the hydrogen gas from leaking from a pump chamber 35 along the drive shaft 46. The motor chamber 38 is provided with an inlet 32a introducing exhaust gas emitted from the oxygen electrode side of the fuel cell into the motor chamber 38 and an exhaust outlet 32b for exhausting the exhaust gas introduced in the motor chamber 38. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydrogen circulation pump constituting a hydrogen circulation path and a fuel cell system using the hydrogen circulation pump.

  In general, in a fuel cell system mounted on a fuel cell vehicle, hydrogen gas and oxygen gas are required for power generation in order to discharge water generated from the power generation of the fuel cell by the reaction of hydrogen and oxygen from the fuel cell. The fuel cell is supplied more than the amount of consumption. For this reason, hydrogen gas (so-called hydrogen off-gas) discharged from the fuel cell contains unreacted hydrogen that has not been used in the fuel cell. In order to use this hydrogen offgas, the fuel cell system is provided with a hydrogen circulation path for resupplying the hydrogen offgas to the fuel cell, and this hydrogen circulation path is provided with a hydrogen pump for circulating the hydrogen offgas. It has been.

  As the hydrogen pump, for example, an electric roots pump is used. This electric roots type pump is comprised from the pump part and the motor part (drive part) provided with the electric motor. A rotating shaft extends from the electric motor of the motor unit to the pump unit. A pair of rotors are housed in the pump chamber of the pump unit. When the pair of rotors are rotated by the rotation of the rotating shaft accompanying the rotation of the motor unit, the hydrogen off-gas is sucked into the pump chamber, and further discharged from the pump chamber and re-supplied to the fuel cell.

  The hydrogen pump is provided with a configuration for preventing the hydrogen off-gas sucked into the pump chamber from flowing into the motor unit and preventing the hydrogen concentration in the motor unit from becoming an explosive atmosphere due to the hydrogen off-gas. That is, a rubber lip seal is provided between the pump unit and the motor unit and around the rotation shaft. The lip seal suppresses leakage of hydrogen off gas from the pump unit along the rotation shaft to the motor unit, thereby preventing the hydrogen concentration in the motor unit from becoming the explosion atmosphere.

  However, since the lip seal is made of rubber, hydrogen gas passes through the lip seal, leaks from the pump portion, and flows into the motor portion. Therefore, some hydrogen pumps actively introduce high-concentration hydrogen gas into the motor unit to prevent the hydrogen concentration from becoming the explosion atmosphere by making the hydrogen concentration in the motor unit exceed the explosion atmosphere. (For example, refer to Patent Document 1).

The hydrogen pump housing described in Patent Document 1 is provided with a hydrogen gas inlet and outlet, and a motor part (electric motor) and a pump part are sealed in the housing. The high-concentration hydrogen gas supplied from the hydrogen supply source is sucked into the housing from the suction port, the hydrogen concentration in the housing is made higher than the explosion atmosphere, and further compressed by the compressor and discharged from the discharge port. It is discharged out of the housing.
JP 2004-251127 A

  By the way, in the hydrogen pump disclosed in Patent Document 1, high-concentration hydrogen gas is supplied into the motor unit. For this reason, if the motor part is manufactured using a material that becomes brittle by hydrogen, the motor part becomes brittle by high-concentration hydrogen gas. For this reason, in the hydrogen pump disclosed in Patent Document 1, it is necessary to manufacture the motor unit by selecting a material having high resistance to hydrogen gas.

  The present invention uses a hydrogen circulation pump that can prevent the hydrogen concentration in the motor chamber from becoming an explosive atmosphere and can manufacture the motor chamber without considering resistance to hydrogen gas, and the hydrogen circulation pump. It is to provide a fuel cell system.

  The hydrogen circulation pump according to the present invention provides the hydrogen circulation of a fuel cell system including a hydrogen circulation path that can supply hydrogen gas that has not been used in a fuel cell with hydrogen gas supplied from a hydrogen source and supply the hydrogen gas to the fuel cell. A hydrogen circulation pump constituting a path, comprising a housing, a pump chamber and a motor chamber defined in the housing, a rotating shaft disposed at least in the pump chamber and the motor chamber, and the interior of the housing A partition section partitioned into a pump chamber and a motor chamber; a shaft hole formed in the partition section through which the rotating shaft is inserted; and a shaft seal that suppresses leakage of hydrogen gas from the pump chamber to the motor chamber. A gas transfer body for transferring hydrogen gas based on rotation of the rotary shaft in the pump chamber, and an electric motor for rotating the rotary shaft in the motor chamber. The motor chamber is provided with an introduction port for introducing exhaust gas discharged from the oxygen electrode side of the fuel cell into the motor chamber, and at least an exhaust port for discharging the exhaust gas introduced into the motor chamber. .

  According to this, the exhaust gas from the oxygen electrode side of the fuel cell is introduced into the motor chamber from the introduction port, and discharged from the motor chamber to the outside of the motor chamber, whereby the exhaust gas can be circulated into the motor chamber. For this reason, even if hydrogen gas permeates the shaft seal and flows from the pump chamber toward the motor chamber, the hydrogen gas can be discharged out of the motor chamber together with the exhaust gas flowing through the motor chamber. Therefore, the hydrogen gas does not stay in the motor chamber, and the hydrogen concentration in the motor chamber can be kept very low to prevent an explosion atmosphere. Further, since the hydrogen concentration in the motor chamber can be kept very low, the motor chamber can be manufactured without considering the resistance to hydrogen gas.

Further, the introduction port and the discharge port may be provided at a position on the partition portion side in the motor chamber and facing the radial direction of the rotation shaft.
According to this, the exhaust gas is introduced into the motor chamber from the introduction port, and discharged from the discharge port to the outside of the motor chamber, whereby the exhaust gas is circulated in the direction transverse to the radial direction of the rotating shaft on the partition side of the motor chamber. Can be made. As a result, an air curtain made of exhaust gas is formed on the partition portion side of the motor chamber, and hydrogen gas can be prevented from flowing into the electric motor side in the motor chamber by the air curtain.

The introduction port and the discharge port may be provided on both end sides of the motor chamber along the axial direction of the rotation shaft and on the opposite side via the rotation shaft.
According to this, exhaust gas can be circulated from one end side to the other end side of the motor chamber by being introduced into the motor chamber from the introduction port and discharged from the discharge port to the outside of the motor chamber. As a result, most of the hydrogen gas flowing into the motor chamber can be discharged out of the motor chamber together with the exhaust gas.

  Further, the hydrogen circulation pump of the present invention is the fuel cell system provided with a hydrogen circulation path that can supply the hydrogen gas that has not been used in the fuel cell with the hydrogen gas supplied from the hydrogen source to supply the fuel cell. A hydrogen circulation pump constituting a hydrogen circulation path, comprising: a housing; a pump chamber and a motor chamber defined in the housing; a rotary shaft disposed at least in the pump chamber and the motor chamber; A partition portion that partitions the pump chamber and the motor chamber, a shaft hole that is formed in the partition portion and through which the rotating shaft is inserted, and a shaft seal that suppresses leakage of hydrogen gas from the pump chamber to the motor chamber A gas transfer body for transferring hydrogen gas based on the rotation of the rotary shaft in the pump chamber, and the rotary shaft is driven to rotate in the motor chamber. An electric motor, and a gas chamber is defined between the partition portion side in the pump chamber, the partition portion side in the motor chamber, or between the pump chamber and the motor chamber. A rotating shaft is provided, and the gas chamber has an inlet for introducing exhaust gas discharged from the oxygen electrode side of the fuel cell into the gas chamber, and an exhaust for discharging at least the exhaust gas introduced into the gas chamber. And an exit.

  According to this, hydrogen gas that has passed through the shaft seal and has flowed from the pump chamber toward the motor chamber can be introduced into the gas chamber. Then, the exhaust gas from the oxygen electrode side of the fuel cell is introduced into the gas chamber from the introduction port, and discharged from the discharge port to the outside of the gas chamber, whereby the exhaust gas can be circulated into the gas chamber. As a result, the hydrogen gas introduced into the gas chamber can be discharged out of the gas chamber by the exhaust gas from the oxygen electrode side, and the hydrogen gas can be prevented from staying on the motor chamber side than the gas chamber. Therefore, the hydrogen concentration in the motor chamber can be kept very low and an explosion atmosphere can be prevented. Further, since the hydrogen concentration in the motor chamber can be kept very low, the motor chamber can be manufactured without considering the resistance to hydrogen gas.

  The electric motor may be an embedded magnet type motor including a stator and a rotor provided on the rotating shaft inside the stator, and further having a rare earth permanent magnet embedded in the rotor.

  According to this, since the hydrogen concentration in the motor chamber can be kept very low, the electric motor in the motor chamber can be selected without considering the resistance to hydrogen gas. For this reason, an embedded magnet type motor in which a rare earth permanent magnet that is easily embrittled by hydrogen gas is embedded in the rotor can be used as the electric motor. The embedded magnet type motor in which the rare earth permanent magnet is embedded in the rotor is smaller in size than the embedded magnet type motor in which a magnet other than the rare earth permanent magnet is embedded in the rotor, and has high torque and high efficiency. Low heat generation. Therefore, by using an embedded magnet type motor in which a rare earth permanent magnet is embedded in a rotor as an electric motor, the motor chamber can be reduced in size, and as a result, the size of the hydrogen circulation pump can be reduced, and the hydrogen circulation pump Performance can be improved.

  The shaft seal may be a lip seal. According to this, the hydrogen gas flowing from the pump chamber toward the motor chamber is discharged out of the motor chamber by the exhaust gas introduced into the motor chamber. Therefore, a lip seal is sufficient for the structure of the shaft seal that suppresses the leakage of hydrogen gas from the pump chamber along the rotating shaft. For this reason, for example, the structure of the shaft seal can be simplified and downsized as compared with the case where a shaft seal means using a diaphragm, a magnet coupling, or hydraulic pressure is provided as the shaft seal.

  A fuel cell system using a hydrogen circulation pump according to the present invention uses the hydrogen circulation pump according to any one of claims 1 to 6 in a hydrogen circulation path, and the introduction port and the fuel cell. The oxygen electrode side was connected by an introduction pipe, and a discharge pipe was connected to the discharge port.

  According to this, in the fuel cell system, the exhaust gas from the oxygen electrode side of the fuel cell is introduced into the introduction port and discharged from the discharge port, so that hydrogen gas does not stay in the motor chamber, and the hydrogen in the motor chamber does not stay. The concentration can be kept very low to prevent an explosive atmosphere. Therefore, it is possible to prevent the hydrogen concentration in the motor chamber from becoming an explosive atmosphere by using the existing configuration in the fuel cell system and further using the exhaust gas from the oxygen electrode side that has been discharged.

  The introduction pipe may be provided with a flow rate adjusting valve, and the discharge pipe may be provided with a throttle. According to this, the opening degree of the flow rate adjusting valve can be adjusted depending on the amount of hydrogen gas transferred in the pump chamber, and the exhaust gas emission amount can be reduced by the throttle. As a result, it is possible to prevent the pressure in the pump chamber from becoming too high or too low in the housing.

  According to the present invention, the hydrogen concentration in the motor chamber can be prevented from becoming an explosive atmosphere, and the motor chamber can be manufactured without considering the resistance to hydrogen gas.

(First embodiment)
A first embodiment in which the present invention is embodied in a hydrogen circulation pump and a fuel cell system will be described below with reference to FIGS. FIG. 1 is a configuration diagram of a fuel cell system.

  As shown in FIG. 1, the fuel cell system 10 includes a fuel cell 11, an oxygen supply unit 12, and a hydrogen supply unit 13. The fuel cell 11 is composed of, for example, a polymer electrolyte fuel cell, and reacts oxygen supplied from the oxygen supply unit 12 and hydrogen supplied from the hydrogen supply unit 13 to generate DC electric energy (DC power). appear.

  The oxygen supply means 12 includes an air compressor 14 for supplying compressed air. The air compressor 14 is connected to an oxygen supply port (not shown) on the cathode side (oxygen electrode side) of the fuel cell 11 via a conduit 15. A humidifier (not shown) is provided in the middle of the pipe line 15. An oxygen discharge port (not shown) on the oxygen electrode side of the fuel cell 11 is connected to a discharge pipe 16 that discharges water in a steam state generated by a chemical reaction for power generation and unreacted air. Yes. The unreacted air discharged from the oxygen electrode side of the fuel cell 11 has an oxygen concentration lower than that before being supplied to the fuel cell 11, and is an inert gas containing nitrogen gas.

  The hydrogen supply means 13 includes a hydrogen tank 22 as a hydrogen source. The hydrogen tank 22 is connected to a hydrogen supply port (not shown) on the anode side (hydrogen electrode side) of the fuel cell 11 via a pipe 23, and a regulator (not shown) is provided in the middle of the pipe 23. Yes. The regulator is a pressure control valve that reduces the hydrogen gas stored in the hydrogen tank 22 at a high pressure to a predetermined pressure and supplies the hydrogen gas at a constant pressure.

  Further, the hydrogen supply means 13 combines the hydrogen gas (hydrogen) that has not been used in the fuel cell 11 with the hydrogen gas supplied from the hydrogen tank 22 (hydrogen source) to supply the fuel cell 11 with a hydrogen circulation path 17. It has. The hydrogen circulation path 17 is provided with a hydrogen circulation pump P. The hydrogen circulation pump P is configured to send out hydrogen gas. In this embodiment, an electric roots type pump is used. The hydrogen circulation pump P includes a pump unit 31 that transfers hydrogen gas and a drive unit 32 that drives the pump unit 31.

  A pump part 31 of a hydrogen circulation pump P is connected to a hydrogen discharge port (not shown) on the hydrogen electrode side of the fuel cell via a pipe 18, and the pump part 31 supplies hydrogen on the hydrogen electrode side of the fuel cell 11. It is connected to ports (not shown) via pipe lines 19 and 23. The hydrogen circulation path 17 is configured by the hydrogen electrode side of the fuel cell 11, the pipe line 18, the pump portion 31 of the hydrogen circulation pump P, and the pipe lines 19 and 23. In the hydrogen circulation pump P, the drive unit 32 is connected in the middle of the exhaust pipe 16 connected to the oxygen discharge port of the oxygen side electrode through the introduction pipe 24, and in the middle of the introduction pipe 24. A valve V as a flow rate adjusting valve is provided. The valve V adjusts the flow rate of the exhaust gas from the oxygen electrode flowing through the introduction pipe 24 by adjusting the valve opening. A discharge pipe 25 is connected to the drive unit 32, and a throttle 26 is provided in the middle of the discharge pipe 25.

  Next, the hydrogen circulation pump P will be described in detail. FIG. 3 shows a cross-sectional view of the hydrogen circulation pump P of the present embodiment. In FIG. 3, the left side is the front of the hydrogen circulation pump P, and the right side is the rear of the hydrogen circulation pump P.

  As shown in FIG. 3, the housing of the hydrogen circulation pump P of this embodiment includes a rotor housing 33, a gear housing 34 joined to the front end of the rotor housing 33, and a motor joined to the front end of the gear housing 34. And a housing 37. The rotor housing 33 includes a first housing 33a, a second housing 33b, and a third housing 33c.

  In the housing of the hydrogen circulation pump P, a pump chamber 35 defined between the first housing 33a and the second housing 33b is provided. A gear chamber 36 defined between the first housing 33 a and the gear housing 34 is provided in the housing of the hydrogen circulation pump P, and a motor chamber defined between the motor housing 37 and the gear housing 34 is provided. 38 is provided. The housing of the hydrogen circulation pump P is divided into a pump chamber 35 and a motor chamber 38 by the gear housing 34 and the first housing 33a. The gear housing 34 and the first housing 33a are in the pump chamber. A partition portion K that partitions the motor chamber 38 and the motor chamber 38 is formed. An electric motor M is accommodated in the motor chamber 38.

  In the hydrogen circulation pump P, the first housing 33a is provided with a pair of first shaft holes 41, and the second housing 33b is provided with a pair of second shaft holes 42. Further, the gear housing 34 is provided with a third shaft hole 43, and the motor housing 37 is provided with a fourth shaft hole 44.

  The first shaft hole 41, the second shaft hole 42, the third shaft hole 43, and the fourth shaft hole 44 located on the same axis are inserted with a drive shaft 46 as a rotating shaft extending from the electric motor M. Has been. The drive shaft 46 passes through the partition portion K and is disposed in the motor chamber 38 and the pump chamber 35. The first shaft hole 41 and the third shaft hole 43 constitute a shaft hole through which the drive shaft 46 is inserted in the partition portion K.

  The drive shaft 46 includes a first bearing 51 fitted into the first shaft hole 41, a second bearing 52 fitted into the second shaft hole 42, a third bearing 53 fitted into the third shaft hole 43, and It is rotatably supported by the housings 33a, 33b, 34, and 37 through a fourth bearing 54 fitted in the fourth shaft hole 44. A driven shaft 47 parallel to the drive shaft 46 is inserted through the other first shaft hole 41 and second shaft hole 42. The driven shaft 47 is rotatably supported on the housings 33a and 33b via a first bearing 51 fitted in the first shaft hole 41 and a second bearing 52 fitted in the second shaft hole 42. Has been.

  Lip seals 48 as shaft seals are interposed between the peripheral surfaces of the first to third shaft holes 41 to 43 provided along the drive shaft 46 and the peripheral surface of the drive shaft 46. The lip seal 48 provided in the first shaft hole 41 and the third shaft hole 43 suppresses leakage of hydrogen gas from the pump chamber 35 to the motor chamber 38 along the drive shaft 46. The lip seal 48 provided in the second shaft hole 42 suppresses leakage of hydrogen gas from the pump chamber 35 along the drive shaft 46 to the outside of the hydrogen circulation pump P. On the other hand, lip seals 48 serving as shaft seals are interposed between the peripheral surfaces of the first and second shaft holes 41, 42 provided along the driven shaft 47 and the peripheral surface of the driven shaft 47. The lip seal 48 provided in the first shaft hole 41 suppresses leakage of hydrogen gas from the pump chamber 35 to the gear chamber 36 (motor chamber 38 side) along the driven shaft 47 and is provided in the second shaft hole 42. The formed lip seal 48 suppresses leakage of hydrogen gas from the pump chamber 35 along the driven shaft 47 to the outside of the hydrogen circulation pump P.

  As shown in FIG. 2, a drive rotor 55 as a gas transfer body is fixed to the drive shaft 46 disposed in the pump chamber 35, and a driven shaft 47 in the pump chamber 35 is set as a gas transfer body. The driven rotor 56 is fixed. The drive rotor 55 and the driven rotor 56 are formed in a double leaf shape (saddle shape) in a cross-sectional view orthogonal to the axial direction of the drive shaft 46 and the driven shaft 47. The drive rotor 55 and the driven rotor 56 are accommodated in the pump chamber 35 in a state of being engaged with each other.

  The pump chamber 35 is provided with the suction port 31 a for sucking the hydrogen gas discharged from the hydrogen electrode side into the pump chamber 35, and the suction port 31 a is formed through the second housing 33 b of the rotor housing 33. Has been. The suction port 31 a is connected to the hydrogen discharge port of the fuel cell 11 through the pipe line 18. The pump chamber 35 is provided with a discharge port 31b for discharging hydrogen gas from the pump chamber 35. The discharge port 31b is formed in the rotor housing 33 at a position opposite to the suction port 31a. The discharge port 31 b is connected to a hydrogen supply port on the hydrogen electrode side of the fuel cell 11 via pipe lines 19 and 23.

  Then, due to the rotation (transfer operation) of the drive rotor 55 and the driven rotor 56 in the pump chamber 35 based on the rotation of the drive shaft 46 and the driven shaft 47, hydrogen gas is sucked into the pump chamber 35 from the suction port 31a and further discharged. It is discharged out of the pump chamber 35 from the outlet 31b. By the suction and discharge of the hydrogen gas, the hydrogen gas is transferred on the hydrogen circulation path 17.

  As shown in FIG. 3, the gear chamber 36 accommodates a drive gear 58 fixed to the drive shaft 46 and a driven gear 59 fixed to the driven shaft 47 in a meshed state. The drive shaft 46 and the driven shaft 47 are gear-connected by the drive gear 58 and the driven gear 59.

  The electric motor M in the drive unit 32 includes a stator 39 fixed to the inner peripheral surface 37a of the motor housing 37 in the motor chamber 38, and a rotor 40 provided on the drive shaft 46 inside the stator 39. This is an embedded magnet type motor (so-called IPM motor) in which a magnet 40 a is embedded in the rotor 40. A rare earth permanent magnet is used as the magnet 40a. The electric motor M rotates the drive shaft 46 by receiving electric power from a coil (not shown) of the stator 39. In the drive unit 32, gas passages 49 extending in the axial direction of the drive shaft 46 are provided at a plurality of locations between the inner peripheral surface 37 a of the motor housing 37 and the outer peripheral surface of the stator 39.

  The introduction port 32 a is provided through the motor housing 37 on the base end side of the motor chamber 38, that is, on the partition portion K side (the rear side of the motor housing 37). The oxygen electrode side of the fuel cell 11 is connected to the introduction port 32 a via the exhaust pipe 16 and the introduction pipe 24. Further, the discharge port 32 b is provided through the motor housing 37 at the front end side of the motor chamber 38 (front side of the motor housing 37). The discharge pipe 25 is connected to the discharge port 32b. The introduction port 32 a is provided on one end side of the drive shaft 46 in the motor chamber 38, and the discharge port 32 b is provided on the other end side of the drive shaft 46 in the motor chamber 38. That is, the introduction port 32 a and the discharge port 32 b are provided on both ends of the motor chamber 38 along the axial direction of the drive shaft 46 and on the opposite side through the drive shaft 46.

  Next, the operation of the fuel cell system 10 having the above configuration will be described. In the fuel cell system 10, hydrogen gas is supplied from the hydrogen tank 22 to the hydrogen electrode side of the fuel cell 11. Further, the air compressor 14 is driven, and air is pressurized to a predetermined pressure and supplied to the oxygen electrode side of the fuel cell 11. At this time, the supply amount of hydrogen gas (hydrogen) and the supply amount of air (oxygen) are determined by the chemical reaction in the fuel cell 11 while the hydrogen gas and air pass through the passage corresponding to the hydrogen electrode side or the oxygen electrode side. More than the amount consumed. In the fuel cell 11, oxygen and hydrogen react to generate power, and water generated by a chemical reaction for power generation is discharged out of the fuel cell 11 from the exhaust pipe 16 together with unreacted air in the state of water vapor. The

  In the hydrogen circulation pump P, when the drive shaft 46 is rotated by the drive of the electric motor M in the drive unit 32, the driven shaft 47 rotates in a direction different from the drive shaft 46 through the meshing connection of the drive gear 58 and the driven gear 59. To do. Then, in the pump chamber 35, the drive rotor 55 and the driven rotor 56 rotate. Along with the rotation of the drive rotor 55 and the driven rotor 56 (the transfer operation of the gas transfer body), the hydrogen gas discharged from the hydrogen electrode side (hydrogen gas not used in the fuel cell 11) is sucked through the pipe 18 It is sucked into the pump chamber 35 from 31a. Thereafter, the hydrogen gas sucked into the pump chamber 35 is discharged out of the pump chamber 35 from the discharge port 31b. The hydrogen gas discharged from the hydrogen electrode side of the fuel cell 11 by the transfer of the hydrogen gas in the pump portion 31 of the hydrogen circulation pump P is merged with the hydrogen gas supplied from the hydrogen tank 22 through the pipe line 19. Then, it is supplied again to the hydrogen electrode side of the fuel cell 11.

  Further, unreacted air (exhaust gas) discharged from the oxygen electrode side to the exhaust pipe 16 is introduced into the introduction port 32 a of the drive unit 32 through the introduction pipe 24 and introduced into the motor chamber 38. Here, when the amount of hydrogen gas transferred in the pump chamber 35 is large and the pressure in the pump chamber 35 is higher than the pressure in the motor chamber 38, the opening degree of the valve V is increased. Then, a large amount of exhaust gas is introduced into the motor chamber 38, and the pressure in the motor chamber 38 rises due to the throttle 26, and the pressure in the motor chamber 38 approaches the pressure in the pump chamber 35. On the other hand, when the amount of hydrogen gas transferred in the pump chamber 35 is small and the pressure in the pump chamber 35 is lower than the pressure in the motor chamber 38, the opening degree of the valve V is reduced and the pressure in the motor chamber 38 is pumped. The pressure in the chamber 35 is brought close to. That is, by adjusting the opening degree of the valve V and narrowing it with the throttle 26, the pressure difference between the pressure in the pump chamber 35 and the pressure in the motor chamber 38 is reduced, and only the pressure in the pump chamber 35 becomes too high in the housing. Or too low.

  Now, it is suppressed by the lip seal 48 that the hydrogen gas in the pump chamber 35 leaks to the motor chamber 38 along the drive shaft 46, but the hydrogen gas permeates the lip seal 48 and flows into the motor chamber 38. To do. At this time, exhaust gas from the oxygen electrode side is introduced into the motor chamber 38 from the introduction port 32a. This exhaust gas is an inert gas having a low oxygen concentration, and flows in the motor chamber 38 without reacting with hydrogen gas. An introduction port 32 a is provided on the rear side of the motor housing 37, and a discharge port 32 b is provided on the front side of the motor housing 37. That is, the introduction port 32 a and the discharge port 32 b are provided at positions that are displaced in both ends of the motor chamber 38 along the axial direction of the drive shaft 46. Further, a plurality of gas passages 49 extending in the axial direction of the drive shaft 46 are formed between the inner peripheral surface 37 a of the motor housing 37 and the stator 39.

  For this reason, the exhaust gas introduced into the motor chamber 38 from the introduction port 32a circulates in the motor chamber 38 from the rear side to the front side along the axial direction of the drive shaft 46, and then from the discharge port 32b to the outside of the motor chamber 38. Discharged. That is, exhaust gas flows through the entire motor chamber 38. For this reason, hydrogen gas and other gases (for example, gas originally present in the motor chamber 38) flowing from the pump chamber 35 toward the motor chamber 38 are discharged from the discharge port 32b through the motor chamber 38 by the flow of the exhaust gas. The hydrogen gas is prevented from staying in the motor chamber 38 by being discharged to the outside.

According to the above embodiment, the following effects can be obtained.
(1) The introduction port 32a and the discharge port 32b are provided in the motor chamber 38 of the hydrogen circulation pump P, and exhaust gas from the oxygen electrode side of the fuel cell 11 is introduced into the motor chamber 38 from the introduction port 32a. After the inside was circulated, the motor chamber 38 was discharged from the discharge port 32b. For this reason, even if hydrogen gas in the pump chamber 35 passes through the lip seal 48 (shaft seal) and flows from the pump chamber 35 toward the motor chamber 38, the hydrogen gas can be discharged from the motor chamber 38 together with the exhaust gas. . Therefore, in the hydrogen circulation pump P, it is possible to prevent the hydrogen concentration in the motor chamber 38 from rising due to the hydrogen gas flowing in from the pump chamber 35. As a result, the hydrogen concentration in the motor chamber 38 can be kept very low, It is possible to prevent the hydrogen concentration from becoming the explosion atmosphere (4% to 75%).

  (2) Further, in the hydrogen circulation pump P, the hydrogen concentration in the motor chamber 38 can be kept very low. For example, as in the case where high concentration hydrogen gas is introduced into the motor chamber 38, There is no need to manufacture the motor chamber 38 with a material that can withstand a high concentration of hydrogen gas. Therefore, it is not necessary to select a material for manufacturing the motor chamber 38 in consideration of resistance to hydrogen gas, and the selection range of materials for manufacturing the motor chamber 38 can be expanded.

  (3) Since the hydrogen concentration in the motor chamber 38 can be kept very low, the electric motor M in the motor chamber 38 can be selected without considering resistance to hydrogen gas. For this reason, as the electric motor M, it is possible to use an embedded magnet type motor in which a rare earth permanent magnet that is easily embrittled by hydrogen gas (hydrogen) is embedded in the rotor 40. Therefore, as compared with the case where an embedded magnet type motor in which a magnet other than a rare earth permanent magnet is embedded in the rotor 40 is used as the electric motor M, the electric motor M can be reduced in size, and can have high torque and high efficiency.・ Low heat generation can be achieved. Since the electric motor M can be reduced in size, the physique of the hydrogen circulation pump P can be reduced in size, and further, the performance of the hydrogen circulation pump P can be improved by improving the performance of the electric motor M.

  (4) Hydrogen gas leakage from the pump chamber 35 to the motor chamber 38 along the drive shaft 46 is suppressed by a rubber lip seal 48. The hydrogen gas passes through the lip seal 48 and flows toward the motor chamber 38, but after flowing into the motor chamber 38, the hydrogen gas is discharged out of the motor chamber 38 by the exhaust gas introduced into the motor chamber 38. Therefore, the lip seal 48 is sufficient for the shaft seal of the drive shaft 46. For example, the shaft seal of the drive shaft 46 is compared with the case where a shaft seal means using a diaphragm, a magnet coupling, or hydraulic pressure is provided as the shaft seal. The configuration can be simplified and reduced in size, and the physique of the hydrogen circulation pump P can be reduced in size. Further, since the lip seal 48 is less expensive than the shaft seal means using the magnet coupling or hydraulic pressure, the manufacturing cost of the hydrogen circulation pump P can be suppressed.

  (5) The fuel cell system 10 is configured to introduce exhaust gas discharged from the oxygen electrode side of the fuel cell 11 into the motor chamber 38 and discharge hydrogen gas in the motor chamber 38 to the outside of the motor chamber 38. Yes. That is, it is possible to prevent the hydrogen concentration in the motor chamber 38 from becoming an explosive atmosphere by using the existing configuration in the fuel cell system 10 and reusing the exhaust gas. Therefore, the cost associated with the complexity of the configuration of the fuel cell system 10 compared to the case where a new discharge means is provided in the fuel cell system 10 in order to discharge the hydrogen gas in the motor chamber 38 to the outside of the motor chamber 38. The rise can be prevented.

  (6) The exhaust gas from the oxygen electrode side is an inert gas having a very low oxygen concentration when oxygen is consumed in the fuel cell 11. For this reason, even if the exhaust gas is introduced into the motor chamber 38, the exhaust gas hardly reacts with the hydrogen gas in the motor chamber 38, and a chemical reaction can be prevented from occurring in the motor chamber 38. Therefore, even if the exhaust gas from the oxygen electrode side is introduced into the motor chamber 38, the fuel cell system 10 does not malfunction.

  (7) A valve V is provided upstream of the motor chamber 38, and a throttle 26 is provided downstream of the motor chamber 38. Then, in the hydrogen circulation pump P, the opening degree of the valve V is adjusted depending on the amount of hydrogen gas transferred in the pump chamber 35, and the pressure of the pump chamber 35 is reduced by reducing the flow rate of the exhaust gas by the throttle 26. The differential pressure between the pressures in the motor chamber 38 can be reduced. As a result, it is possible to suppress the lip seal 48 from being strongly pressed against the drive shaft 46 by reducing the differential pressure, and the life of the lip seal 48 can be extended.

  (8) The introduction port 32 a is provided on the rear side in the motor chamber 38, and the discharge port 32 b is provided on the front side in the motor chamber 38. That is, the introduction port 32 a and the discharge port 32 b are positions that are displaced at both end sides along the axial direction of the drive shaft 46 in the motor chamber 38, and are provided on the opposite sides via the drive shaft 46. For this reason, the exhaust gas introduced into the motor chamber 38 from the inlet 32a flows through the motor chamber 38 from the rear side to the front side, and is then discharged from the outlet port 32b. Therefore, exhaust gas can be circulated in the entire motor chamber 38, and most of the hydrogen gas in the motor chamber 38 can be scavenged by the exhaust gas.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. In addition, since 2nd Embodiment is a structure which only changed the drive part 32 of 1st Embodiment, the overlapping description is abbreviate | omitted about the same part.

  As shown in FIG. 4, in the drive unit 32, a partition wall 60 is fitted inside the motor housing 37, and the motor chamber 38 is partitioned into an electric motor M side and a partition portion K side by the partition wall 60. . A gas chamber 61 surrounded by the motor housing 37, the front end of the gear housing 34, and the rear end of the partition wall 60 is formed on the partition K side in the motor chamber 38.

  Further, the partition wall 60 is provided with a fifth shaft hole 62, and a drive shaft 46 is inserted into the fifth shaft hole 62, and the drive shaft 46 is provided in the gas chamber 61 in addition to the pump chamber 35 and the motor chamber 38. Is also disposed. The drive shaft 46 is rotatably supported also in the partition wall 60 by a fifth bearing 63 fitted in the fifth shaft hole 62. In the fifth shaft hole 62, a lip seal 48 as a shaft seal is interposed between the peripheral surface of the fifth shaft hole 62 and the peripheral surface of the drive shaft 46.

  The gas chamber 61 is provided in an annular shape around the drive shaft 46. The gas chamber 61 is provided with an introduction port 32 a and a discharge port 32 b that penetrate the motor housing 37, and the introduction port 32 a and the discharge port 32 b communicate with the gas chamber 61. The introduction port 32 a and the discharge port 32 b are provided at positions that face the radial direction of the drive shaft 46, and are provided on the opposite side through the drive shaft 46. Further, the oxygen electrode side of the fuel cell 11 is connected to the introduction port 32 a via the exhaust pipe 16 and the introduction pipe 24. A discharge pipe 25 is connected to the discharge port 32b. A valve V is provided in the middle of the introduction pipe 24, and a throttle 26 is provided in the middle of the discharge pipe 25. Note that the gas passage 49 is not formed in the second embodiment.

  In the second embodiment, hydrogen gas that has passed through the lip seal 48 and has flowed from the pump chamber 35 toward the motor chamber 38 is introduced into the gas chamber 61. At this time, exhaust gas discharged from the oxygen electrode side is introduced into the gas chamber 61 from the introduction port 32a. For this reason, the hydrogen gas staying in the gas chamber 61 is discharged out of the gas chamber 61 (motor chamber 38) together with the exhaust gas.

  Further, the exhaust gas introduced into the gas chamber 61 flows in a direction crossing the gas chamber 61 in the radial direction of the drive shaft 46. As a result, an air curtain is formed in the gas chamber 61 by the exhaust gas flowing from the inlet 32 a to the outlet 32 b, and hydrogen gas flowing from the pump chamber 35 toward the motor chamber 38 is transferred from the gas chamber 61. Inflow to the motor chamber 38 side can be suppressed.

  Depending on the amount of hydrogen gas transferred in the pump chamber 35, the opening degree of the valve V is adjusted, and the flow rate of the exhaust gas is reduced by the restrictor 26 so that the pressure in the pump chamber 35 and the pressure in the gas chamber 61 are reduced. The differential pressure can be reduced. That is, it is suppressed that only the pressure of the pump chamber 35 becomes too high or too low in the housing.

  Since the hydrogen gas flowing from the pump chamber 35 toward the motor chamber 38 is suppressed from flowing from the gas chamber 61 to the motor chamber 38, the hydrogen gas flows from the gas chamber 61 toward the motor chamber 38. Gas flow is suppressed. As a result, the hydrogen concentration in the motor chamber 38 is kept very low, and the hydrogen concentration in the motor chamber 38 is prevented from becoming an explosive atmosphere (4% to 75%).

Therefore, according to the second embodiment, in addition to the effects described in (1) to (7) of the first embodiment, the following effects can also be exhibited.
(9) By providing the partition wall 60 in the housing, the gas chamber 61 is partitioned on the partition portion K side in the motor chamber 38 in the housing, and the inlet 32 a and the outlet 32 b are provided in the gas chamber 61. Yes. For this reason, the hydrogen gas flowing from the pump chamber 35 side toward the motor chamber 38 is introduced into the gas chamber 61. Then, the hydrogen gas introduced into the gas chamber 61 is discharged out of the gas chamber 61 by the exhaust gas from the oxygen electrode side. Therefore, by providing the gas chamber 61, it is possible to prevent the hydrogen gas from staying on the motor chamber 38 side than the gas chamber 61, and it is necessary to set the material of the electric motor M in consideration of the resistance to the hydrogen gas. Disappears.

In addition, you may change each said embodiment as follows.
In each embodiment, the valve V and the throttle 26 may be deleted.
In each embodiment, instead of the lip seal 48, for example, a diaphragm, a magnet coupling, or a shaft seal means using hydraulic pressure may be used as the shaft seal.

  In the second embodiment, a branch pipe is connected to the introduction pipe 24 connected to the introduction port 32a, and the branch pipe is connected to a room in which the electric motor M in the motor chamber 38 is accommodated to accommodate the electric motor M. The exhaust gas from the oxygen electrode side may be introduced into the chamber. With this configuration, the electric motor M can be cooled with exhaust gas, so that the efficiency of the electric motor M can be increased and the electric motor M can be reduced in size.

  In the first embodiment, the introduction port 32 a and the discharge port 32 b may be provided at a position facing the radial direction of the drive shaft 46 on the partition K side in the motor chamber 38, that is, on the rear side of the motor chamber 38. . With this configuration, the exhaust gas introduced into the motor chamber 38 flows in the motor chamber 38 in a direction transverse to the radial direction of the drive shaft 46. As a result, an air curtain is formed on the partition portion K side of the motor chamber 38 by the exhaust gas flowing from the introduction port 32a to the discharge port 32b, and the hydrogen gas flowing from the pump chamber 35 side to the motor chamber 38 is transferred to the electric motor M. Inflow to the side can be suppressed.

In the second embodiment, a partition wall 60 may be fitted inside the second housing 33 b, and the gas chamber 61 may be partitioned on the partition portion K side in the pump chamber 35 by the partition wall 60.
In the first embodiment, the space defined between the second housing 33b and the third housing 33c behind the hydrogen circulation pump P is a gear chamber, and the drive shaft 46 disposed in the gear chamber The drive gear 58 is fixed, and the driven gear 59 is fixed. Further, a space defined between the first housing 33a and the gear housing 34 and between the pump chamber 35 and the motor chamber 38 may be a gas chamber, and an introduction port and a discharge port may be provided in the gas chamber. Good. At this time, the introduction port and the discharge port are provided through the gear housing 34, and the drive shaft 46 is disposed in the gas chamber.

  In each embodiment, the hydrogen circulation pump P may be configured such that the electric motor M and the drive rotor 55 (rotor) are not connected by the single drive shaft 46. That is, a drive gear 58 is fixed to a drive shaft 46 extending from the electric motor M, and the drive gear 58 is disposed in the gear chamber 36. At this time, the drive shaft 46 extends from the electric motor M to the gear chamber 36 and is not disposed in the pump chamber 35. In the gear chamber 36, the driven gears 59 are meshed and connected to both sides of the drive gear 58, and the driven shafts 47 as the rotation shafts are fixed to the driven gears 59. Then, each driven shaft 47 fixed to each driven gear 59 is disposed in the pump chamber 35, and a rotor as a gas transfer body is fixed to each driven shaft 47 and is engaged with each other in the pump chamber 35. To house.

In each embodiment, the drive shaft 46 may be disposed outside the motor chamber 38 through the motor housing 37.
In each embodiment, the electric motor M may not be an embedded magnet type motor but may be a surface magnet type motor. The magnet 40a may be a magnet other than a rare earth permanent magnet. Furthermore, the electric motor M may be an induction motor.

  In each embodiment, as the exhaust gas, an exhaust gas having a low oxygen concentration obtained by filtering oxygen from an oxygen supply source with a filter or the like may be introduced into the motor chamber 38 instead of the exhaust gas from the oxygen electrode side.

  In each embodiment, the hydrogen circulation pump P may be an electric scroll pump that transfers a hydrogen gas by rotating a scroll as a gas transfer body based on rotation of a rotating shaft. Alternatively, the hydrogen circulation pump P may be an electric diaphragm pump that transfers a hydrogen gas by moving a diaphragm as a gas transfer body based on rotation of a rotating shaft.

In each embodiment, the fuel cell system 10 may be configured to introduce all the exhaust gas from the oxygen electrode side into the motor chamber 38.
In each embodiment, a heat exchanger may be provided in the middle of the introduction pipe 24 in the fuel cell system 10. With this configuration, the exhaust gas from the oxygen electrode side is cooled by the heat exchanger before being introduced into the motor chamber 38. For this reason, the electric motor M is efficiently cooled in the motor chamber 38.

  In each embodiment, a gas-liquid separator may be provided in the middle of the hydrogen circulation path 17 in the fuel cell system 10.

The block diagram of a fuel cell system. FIG. 4 is a cross-sectional view taken along line 2-2 of FIG. 3 showing the pump chamber of the hydrogen circulation pump. Sectional drawing which shows the hydrogen circulation pump of 1st Embodiment. Sectional drawing which shows the hydrogen circulation pump of 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS K ... Partition part, M ... Electric motor, P ... Hydrogen circulation pump, V ... Valve as flow control valve, 10 ... Fuel cell system, 11 ... Fuel cell, 17 ... Hydrogen circulation path, 22 ... Hydrogen tank as hydrogen source 24 ... Introducing pipe, 25 ... Draining pipe, 26 ... Throttling, 32a ... Introducing port, 32b ... Discharging port, 33 ... Rotor housing constituting the housing, 33a ... First housing constituting the partitioning part, 34 ... Housing and compartment Gear housing constituting part, 35 ... pump chamber, 37 ... motor housing constituting housing, 38 ... motor chamber, 39 ... stator, 40 ... rotor, 40a ... magnet as rare earth permanent magnet, 41 ... constituting shaft hole 1st shaft hole, 43 ... 3rd shaft hole which comprises a shaft hole, 46 ... Drive shaft as a rotating shaft, 48 ... Lip seal as shaft seal, 55 ... As a gas transfer body Drive rotor, 56 ... driven rotor as a gas conveying body, 61 ... gas chamber.

Claims (8)

A hydrogen circulation pump that constitutes the hydrogen circulation path of the fuel cell system having a hydrogen circulation path that can supply the hydrogen gas that has not been used in the fuel cell with the hydrogen gas supplied from a hydrogen source to supply the fuel cell. There,
A housing;
A pump chamber and a motor chamber defined in the housing;
A rotating shaft disposed at least in the pump chamber and the motor chamber;
A partition for partitioning the inside of the housing into the pump chamber and the motor chamber;
A shaft hole formed in the partition and through which the rotating shaft is inserted;
A shaft seal that suppresses leakage of hydrogen gas from the pump chamber to the motor chamber,
The pump chamber includes a gas transfer body that transfers hydrogen gas based on the rotation of the rotating shaft, and the motor chamber includes an electric motor that rotationally drives the rotating shaft,
The motor chamber is provided with an introduction port for introducing exhaust gas discharged from the oxygen electrode side of the fuel cell into the motor chamber and at least an exhaust port for discharging the exhaust gas introduced into the motor chamber. A hydrogen circulation pump. 2. The hydrogen circulation pump according to claim 1, wherein the introduction port and the discharge port are provided on the partitioning portion side in the motor chamber and at positions facing the radial direction of the rotation shaft. 2. The hydrogen circulation pump according to claim 1, wherein the introduction port and the discharge port are provided at both ends of the motor chamber along the axial direction of the rotating shaft and on opposite sides through the rotating shaft. A hydrogen circulation pump that constitutes the hydrogen circulation path of the fuel cell system having a hydrogen circulation path that can supply the hydrogen gas that has not been used in the fuel cell with the hydrogen gas supplied from a hydrogen source to supply the fuel cell. There,
A housing;
A pump chamber and a motor chamber defined in the housing;
A rotating shaft disposed at least in the pump chamber and the motor chamber;
A partition for partitioning the inside of the housing into the pump chamber and the motor chamber;
A shaft hole formed in the partition and through which the rotating shaft is inserted;
A shaft seal that suppresses leakage of hydrogen gas from the pump chamber to the motor chamber,
The pump chamber includes a gas transfer body that transfers hydrogen gas based on the rotation of the rotating shaft, and the motor chamber includes an electric motor that rotationally drives the rotating shaft,
A gas chamber is partitioned between the partition section side in the pump chamber, the partition section side in the motor chamber, or between the pump chamber and the motor chamber, and the rotating shaft is disposed in the gas chamber. The gas chamber is provided with an introduction port for introducing exhaust gas discharged from the oxygen electrode side of the fuel cell into the gas chamber and at least an exhaust port for discharging the exhaust gas introduced into the gas chamber. A hydrogen circulation pump characterized by 5. The electric motor is an embedded magnet type motor including a stator and a rotor provided on the rotating shaft inside the stator, and a rare earth permanent magnet embedded in the rotor. The hydrogen circulation pump according to any one of the above. The hydrogen circulation pump according to any one of claims 1 to 5, wherein the shaft seal is a lip seal. The hydrogen circulation pump according to any one of claims 1 to 6 is used in a hydrogen circulation path,
A fuel cell system, wherein the introduction port and the oxygen electrode side of the fuel cell are connected by an introduction tube, and a discharge tube is connected to the discharge port. The fuel cell system according to claim 7, wherein a flow rate adjusting valve is provided in the introduction pipe, and a throttle is provided in the discharge pipe.

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