JP2007192126A - Electric pump for hydrogen circulation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric pump for hydrogen circulation in which rotors sticking to a pump chamber can be separated, while inhibiting upsizing of the structure. <P>SOLUTION: In the housing of the electric Roots pump 17, an input shaft 31 is held, which is rotated by an electric motor 41, and provided with an input gear G. In the housing, a first rotary shaft 33 is held in parallel with the input shaft 31. The rotary shaft 33 is provided with a first gear G1 engaged with the input gear G and a fixed first rotor 39 housed in a rotor chamber 24. In the housing, a second rotary shaft 35 is held coaxially with the input shaft 31, and provided with a second gear G2 meshed with the first gear G1, and a fixed second-rotor 40 housed in the rotor chamber 24. The backlash of the input gear G and the first gear G1 is set larger than the backlash of the second gear G2 and the first gear G1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to hydrogen constituting a hydrogen circulation path of a fuel cell system provided with a hydrogen circulation path capable of supplying hydrogen gas that has not been used in a fuel cell to hydrogen gas supplied from a hydrogen source to supply the fuel cell. The present invention relates to an electric pump for circulation.

  As a pump that rotates a rotating body by a rotational drive source, sucks fluid into the pump chamber from the suction port by rotation of the rotating body, and discharges the sucked fluid out of the pump chamber from the discharge port, for example, A mechanical supercharger disclosed in Patent Document 1 can be cited. A pulley shaft is rotatably supported on the casing of the mechanical supercharger, and an input gear is fixed to the pulley shaft. In addition, a first rotor shaft and a second rotor shaft are rotatably supported by the casing, and a first rotor is fixed to the first rotor shaft, and a second rotor is mounted on the second rotor shaft. Is fixed. The first rotor and the second rotor are accommodated in a pump chamber defined in the casing. Further, a first timing gear is fixed to the first rotor shaft, and a second timing gear is fixed to the second rotor shaft. The second rotor shaft is disposed coaxially with the pulley shaft. The input gear and the second timing gear mesh with the first timing gear.

  In the mechanical supercharger configured as described above, when the pulley shaft rotates based on the rotation of the engine as the rotational drive source, the rotational torque of the pulley shaft is transmitted through the input gear, the first timing gear, and the second timing gear. It is transmitted to the first rotor shaft and the second rotor shaft, and the first rotor and the second rotor are rotationally engaged. Due to the rotational meshing of both rotors, air is sucked into the pump chamber from the suction port, and further, the air sucked into the pump chamber is discharged from the discharge port to the outside of the pump chamber, and the discharged air is supplied to the supply destination. It has become so. In other words, the mechanical supercharger is a motive power composed of three shafts of a pulley shaft, a first rotor shaft, and a second rotor shaft, and three gears of an input gear, a first timing gear, and a second timing gear. A transmission mechanism is provided, and the pair of rotors are rotated by the power transmission mechanism.

Moreover, as a pump which transfers a fluid, there exists an electric pump provided with the electric motor other than the said engine as a rotational drive source. And in the electric pump provided with the said power transmission mechanism, the rotational drive of the said electric motor is transmitted to a 1st rotor and a 2nd rotor via a power transmission mechanism.
JP 2002-213249 A

  By the way, in recent years, a fuel cell vehicle equipped with a fuel cell system equipped with a fuel cell that generates electricity by reacting hydrogen and oxygen and that runs on the electric power generated by the fuel cell has attracted attention. The fuel cell system is provided with a hydrogen circulation path for re-supplying unreacted hydrogen gas (so-called hydrogen off gas) that has not been used in the fuel cell to the fuel cell. The hydrogen circulation path is provided with a pump for transferring the hydrogen off gas.

  When the electric pump provided with the power transmission mechanism is used as the pump, when the first rotor and the second rotor are rotationally engaged based on the rotational drive of the electric motor, hydrogen off-gas is generated by the first rotor and the second rotor. It is sucked into the housed pump chamber. Further, due to the rotational engagement of the first rotor and the second rotor, the hydrogen off-gas discharged to the outside of the pump chamber is mixed with the newly supplied hydrogen gas and re-supplied to the fuel cell. Yes.

  However, in the fuel cell system, water generated as the fuel cell generates power is discharged from the fuel cell together with the hydrogen off gas, and further introduced into the pump chamber together with the hydrogen off gas. Then, the water introduced into the pump chamber enters a state between the inner wall surface of the pump chamber and the end surfaces of the first rotor and the second rotor. Here, for example, when the fuel cell system is stopped from the operating state in a low temperature environment such as below freezing point, the water condenses and freezes, and the freezing causes the inner wall surface of the pump chamber and the end surface of each rotor to stick. It sticks and sticks. In this fixed state, each rotor is peeled off from the inner wall surface of the pump chamber when the operation of the fuel cell system is resumed, so that it is necessary to generate a large torque in the electric motor. As a result, in the pump, it is necessary to provide a large electric motor that can generate a large torque at the time of startup, and the physique has been enlarged.

  The present invention has been made paying attention to such problems existing in the prior art, and its purpose is to peel off the rotating body fixed to the pump chamber while suppressing an increase in size. An object is to provide an electric pump for hydrogen circulation.

  In order to solve the above problems, the invention according to claim 1 is directed to a hydrogen circulation that can supply hydrogen gas that has not been used in a fuel cell to the fuel cell by joining the hydrogen gas supplied from a hydrogen source. An electric pump for hydrogen circulation constituting the hydrogen circulation path of a fuel cell system having a path, wherein an electric motor is accommodated in a housing and a pump chamber is formed, and the pump motor has an electric motor in the pump chamber. A pair of rotating bodies that rotate with rotation are accommodated, and the housing further includes an input shaft that includes an input gear and is rotated by the electric motor, and is disposed in parallel to the input shaft, A first rotating shaft having a first gear meshingly connected to the input gear and having one of the pair of rotating bodies fixed thereto; and disposed coaxially with the input shaft; A second rotating shaft having a second gear meshingly connected to the gear and having the other rotating body fixed thereto is rotatably supported, and backlash between the input gear and the first gear is prevented from occurring in the second gear. It is larger than the backlash between the gear and the first gear.

  According to this configuration, when the electric pump for hydrogen circulation is started with the rotating body and the pump chamber fixed by icing, the input shaft rotates as the electric motor starts and the input gear meshes with the first gear. The input gear collides with the first gear due to the large backlash. Then, an impact torque is generated in the first gear by this collision, and the first rotating shaft can be rotated by the impact torque. For this reason, an impact torque acts on one of the rotating bodies fixed to the first rotating shaft, and the ice that fixes the one rotating body to the pump chamber can be crushed by the impact torque. The rotating body can be peeled off from the pump chamber. And since the 1st rotating shaft and one rotating body can rotate, it becomes possible to transmit the rotational torque of an electric motor to a 2nd rotating shaft via an input gear, a 1st gear, and a 2nd gear. . As a result, the rotation of the second rotating shaft can break the ice with the other rotating body and the pump chamber fixed, and the other rotating body can be peeled off from the pump chamber. Therefore, the pair of rotating bodies can be peeled off from the pump chamber simply by starting up the electric motor, and the hydrogen circulation electric pump is equipped with a large electric motor that generates a large torque for the peeling. There is no need.

  In addition, the input shaft and the second rotating shaft can be rotated independently by inserting a connecting member provided on the other shaft into a connecting hole provided on one of the shafts. It may be connected.

  According to this configuration, by inserting the connecting member into the connecting hole, the peripheral surface of the connecting hole and the peripheral surface of the connecting member can come into contact with each other, and the inclination of both axes can be suppressed by the corresponding contact. It becomes possible.

  The input gear, the first gear, and the second gear may be accommodated in a gear chamber formed in the housing, and the connection hole and the connection member may be disposed in the gear chamber.

  According to this structure, the lubricating oil which maintains the lubrication in the meshing part of each gear is enclosed with the gear chamber in which the connecting hole and the connecting member are arranged. For this reason, the lubricating oil enters between the peripheral surface of the connecting hole and the peripheral surface of the connecting member. Therefore, even if the input shaft and the second rotating shaft are connected by the connecting hole and the connecting member, wear between the connecting hole and the connecting member is reduced by the lubricating oil.

  ADVANTAGE OF THE INVENTION According to this invention, the rotary body fixed to the pump chamber can be peeled off, suppressing the enlargement of a physique.

  Hereinafter, an embodiment in which the electric pump for hydrogen circulation of the present invention is embodied as an electric roots pump used as a hydrogen circulation pump in a fuel cell system will be described with reference to FIGS. First, the fuel cell system 10 includes a fuel cell 11, an oxygen supply means 12, and a hydrogen supply means 13, as shown in FIG. 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). Generate (generate electricity). The oxygen supply means 12 includes a compressor 14 for supplying compressed air, and the compressor 14 is connected to an oxygen supply port (not shown) of the fuel cell 11 via a conduit 15, and in the middle of the conduit 15. A humidifier 16 is provided.

  The hydrogen supply means 13 is provided with an electric roots pump 17 for transferring the hydrogen gas in order to circulate and use the hydrogen gas not used in the fuel cell 11 (so-called hydrogen off-gas). That is, the electric roots pump 17 is provided to supply again the hydrogen off-gas that has not been used in the fuel cell 11 to the fuel cell 11. The electric roots pump 17 is connected to a hydrogen supply port (not shown) of the fuel cell 11 via a pipe line 18 and connected to a hydrogen discharge port (not shown) of the fuel cell 11 via a pipe line 19. Yes. The hydrogen supply means 13 includes a hydrogen tank 20 as a hydrogen source (hydrogen gas supply source). The hydrogen tank 20 is connected to the pipe line 18 via a pipe line 21 provided with a regulator (not shown) on the way. The electric roots pump 17 and the pipes 18 and 19 constitute a hydrogen circulation path that can supply hydrogen off-gas that has not been used in the fuel cell 11 to the fuel cell 11 together with hydrogen gas newly supplied from the hydrogen tank 20. Has been.

  Next, the electric roots type pump 17 will be specifically described. In the following description, for “front” and “rear” of the electric roots pump 17, the direction of the arrow Y shown in FIG.

  As shown in FIG. 1, the housing of the electric Roots type pump 17 of this embodiment is configured by joining a pump housing P and a motor housing M. The pump housing P is formed by joining and fixing a shaft support member 23 to the front end of the rotor housing 22, and further joining and fixing a gear housing 25 to the front end of the shaft support member 23. In the pump housing P, a rotor chamber 24 as a pump chamber is enclosed between the rotor housing 22 and the shaft support member 23. A gear chamber 26 is enclosed between the gear housing 25 and the shaft support member 23. In the gear chamber 26, an input gear G, a first gear G1, and a second gear G2, which will be described later, are disposed, and lubricating oil for reducing wear at the meshing portion between the gears G, G1, and G2. Is enclosed. The motor housing M is joined and fixed to the front end of the gear housing 25. A motor chamber 29 is enclosed between the gear housing 25 and the motor housing M, and an electric motor 41 is accommodated in the motor chamber 29.

  The electric motor 41 includes a stator 42 fixed to the inner surface of the motor housing M, and a rotor 43 that is disposed inside the stator 42 and that can rotate relative to the stator 42 in both forward and reverse directions. Yes. The stator 42 has a stator coil 42a, and the stator coil 42a is electrically connected to an external power source (not shown) through a plurality of lead wires (not shown). The rotor 43 is formed in a cylindrical shape, and the input shaft 31 is press-fitted inside the rotor 43, and the input shaft 31 can rotate integrally with the rotor 43. In the housing, the input shaft 31 is rotatably supported by the motor housing M and the gear housing 25 via a radial bearing 32. An end of the input shaft 31 on the gear housing 25 side protrudes into the gear chamber 26, and an input gear G is fixed to the end of the input shaft 31, and the input gear G is connected to the input shaft 31. And can be rotated together.

  A first rotating shaft 33 is rotatably supported by the gear housing 25 and the shaft support member 23 via a radial bearing 36 so as to be parallel to the input shaft 31. In the first rotating shaft 33, a first gear G <b> 1 is fixed at a place arranged in the gear chamber 26. The first gear G <b> 1 is meshed with the input gear G and can rotate integrally with the first rotation shaft 33. Further, in the first rotating shaft 33, the end on the rotor housing 22 side protrudes into the rotor chamber 24, and one end of the pair of rotating bodies rotates at the end of the first rotating shaft 33. A first rotor 39 as a body is fixed. The first rotor 39 can rotate integrally with the first rotating shaft 33. The first rotor 39 is a two-leaf rotor in which a cross-sectional view orthogonal to the axial direction of the first rotation shaft 33 is formed in a double-leaf shape (saddle shape).

  Further, a second rotating shaft 35 disposed coaxially with the input shaft 31 is supported on the shaft support member 23 via a radial bearing 37 so as to be rotatable. The second rotation shaft 35 is formed in a shorter axis shape than the input shaft 31. An end of the second rotating shaft 35 on the gear housing 25 side protrudes into the gear chamber 26, and a second gear G 2 is fixed to the end of the second rotating shaft 35. The second gear G2 can rotate integrally with the second rotary shaft 35 and is meshed with the first gear G1. Further, in the second rotating shaft 35, the end on the rotor housing 22 side protrudes into the rotor chamber 24, and the end of the rotor housing 22 serves as the other rotating body of the pair of rotating bodies. The second rotor 40 is fixed. The second rotor 40 can rotate integrally with the second rotating shaft 35. The second rotor 40 is a two-leaf rotor in which a cross-sectional view orthogonal to the axial direction of the second rotating shaft 35 is formed in a double leaf shape (saddle shape). In the rotor chamber 24, the first rotor 39 and the second rotor 40 are formed so as to be able to mesh with each other.

  In the second rotating shaft 35, a connecting member 38 that protrudes toward the input shaft 31 protrudes from an end surface facing the input shaft 31. The connecting member 38 is inserted into a connecting hole 31 a that is recessed in the end surface of the input shaft 31 that faces the second rotating shaft 35. Since the connecting member 38 and the connecting hole 31a are disposed in the gear chamber 26, the lubricating oil sealed in the gear chamber 26 enters the connecting hole 31a. When the connecting member 38 is inserted into the connecting hole 31a, a very small clearance (not shown) is formed between the peripheral surface of the connecting member 38 and the peripheral surface of the connecting hole 31a. The member 38 is fitted in the connecting hole 31a. Therefore, the input shaft 31 and the second rotation shaft 35 are coaxial and can rotate independently of each other. The rotor housing 22 has a suction port (not shown) for sucking hydrogen off gas into the rotor chamber 24 and a discharge port (not shown) for discharging the hydrogen off gas sucked into the rotor chamber 24 at a position opposite to the suction port. ) Is formed.

  In the fuel cell system 10 including the electric roots pump 17 having the above-described configuration, when the input shaft 31 rotates based on the rotation of the electric motor 41, the first rotating shaft is connected through the meshing connection between the input gear G and the first gear G1. 33 rotates in a different direction from the input shaft 31. Further, the second rotating shaft 35 rotates in the same direction as the input shaft 31 through the meshing connection of the first gear G1 and the second gear G2. Then, as the electric motor 41 rotates, the first rotating shaft 33 and the second rotating shaft 35 rotate in different directions, and the first rotor 39 and the second rotor 40 rotate in different directions in the rotor chamber 24. To do. In addition, the three shafts of the input shaft 31, the first rotating shaft 33, and the second rotating shaft 35, and the three gears of the input gear G, the first gear G1, and the second gear G2, are used for the electric motor 41. A power transmission mechanism that transmits the rotation to the first rotor 39 and the second rotor 40 is configured.

  Then, the hydrogen off-gas discharged from the fuel cell 11 is sucked into the rotor chamber 24 from the suction port via the pipe line 19 as the first rotor 39 and the second rotor 40 rotate in the rotor chamber 24. Thereafter, the hydrogen off-gas sucked into the rotor chamber 24 along with the rotation of the first rotor 39 and the second rotor 40 is sent out to the discharge port side of the rotor chamber 24, and from the discharge port to the pipe line 18 outside the rotor chamber 24. Discharged. Thereafter, the hydrogen off-gas discharged to the pipe 18 is re-supplied from the pipe 18 to the fuel cell 11 together with hydrogen gas newly supplied from the hydrogen tank 20.

  Next, the power transmission mechanism will be described in detail. In FIG. 2, the lower gear indicates the first gear G1, and the upper gear of the first gear G1 indicates the second gear G2. In FIG. 3, the lower gear indicates the first gear G1, and the upper gear of the first gear G1 indicates the input gear G.

  2 and 3, the teeth of the input gear G are gear teeth Ga, the teeth of the first gear G1 are first gear teeth G1a, and the teeth of the second gear G2 are second gear teeth G2a. To do. The number of gear teeth Ga of the input gear G, the number of first gear teeth G1a of the first gear G1, and the number of second gear teeth G2a of the second gear G2 are the same. 2 and 3 is a pitch circle of the input gear G, a virtual arc PC1 is a pitch circle of the first gear G1, and a virtual arc PC2 is a pitch circle of the second gear G2. To do. Note that the pitch circles PCG, PC1, and PC2 are circles that serve as reference teeth for the gears G, G1, and G2.

  Further, the virtual arc ACG indicated by the two-dot chain line in FIGS. 2 and 3 is the tooth tip circle of the input gear G, the virtual arc AC1 is the tooth tip circle of the first gear G1, and the virtual arc AC2 is the tooth of the second gear G2. It will be the previous yen. The tooth tip circles ACG, AC1, and AC2 are circles that connect the gear teeth Ga, G1a, and G2a of the gears G, G1, and G2, and are formed before the gear teeth Ga, G1a, and G2a are formed. This is the outer circle of the material. In addition, a virtual arc RCG indicated by a two-dot chain line in FIGS. 2 and 3 is a root circle of the input gear G, a virtual arc RC1 is a root circle of the first gear G1, and a virtual arc RC2 is the second gear G2. Tooth circle. The root circles RCG, RC1, and RC2 are circles connecting the gear teeth Ga, G1a, and G2a of the gears G, G1, and G2. The pitch circle PCG of the input gear G and the pitch circle of the second gear G2 are the same size, and the tooth root circle RCG of the input gear G and the tooth root circle RC2 of the second gear G2 are the same size. . Further, the addendum circle ACG of the input gear G is smaller than the addendum circle AC2 of the second gear G2, and the length of the gear teeth Ga of the input gear G is equal to that of the second gear teeth G2a of the second gear G2. It is shorter than the length.

  Further, in the input gear G and the first gear G1, a surface that contacts when the gear teeth Ga and the first gear teeth G1a mesh with each other is a tooth surface GS of the gear teeth Ga, and a tooth surface G1S of the first gear teeth G1a. To do. On the other hand, in the second gear G2, the surface that contacts when the second gear teeth G2a mesh with the first gear teeth G1a of the first gear G1 is defined as a tooth surface G2S of the second gear teeth G2a.

  In the input gear G, the thickness of the gear teeth Ga along the pitch circle PCG is set to the tooth thickness GDa, and the thickness of the gear teeth Ga along the tip circle ACG is set to the tooth thickness GDb. On the other hand, in the second gear G2, the thickness of the second gear tooth G2a along the pitch circle PC2 is set to the tooth thickness G2Da, and the thickness of the second gear tooth G2a along the tooth tip circle AC2 is set to the tooth thickness G2Db. Is set. The tooth thicknesses GDa and GDb of the gear teeth Ga of the input gear G are thinner than the tooth thicknesses G2Da and G2Db of the second gear teeth G2a of the second gear G2.

  Therefore, the play A between the tooth surface GS of the gear tooth Ga and the tooth surface G1S of the first gear tooth G1a is between the tooth surface G2S of the second gear tooth G2a and the tooth surface G1S of the first gear tooth G1a. It is bigger than the play (not shown). That is, the backlash between the input gear G and the first gear G1 is larger than the backlash between the second gear G2 and the first gear G1. The backlash between the second gear G2 and the first gear G1 is normally set to be the same as the backlash formed between the gears, and the backlash between the input gear G and the first gear G1 is It is set larger than the normally set backlash. Since the backlash is set as described above, in the first gear G1 and the second gear G2, the second gear teeth G2a and the first gear teeth G1a quickly mesh with each other, and both gear teeth G1a, The rotational torque of the first rotating shaft 33 is quickly transmitted to the second rotating shaft 35 without any play between the G2a. On the other hand, since the play A between the gear teeth Ga and the first gear teeth G1a is large, the input gear G and the first gear G1 mesh with each other so that the gear teeth Ga collide with the first gear teeth G1a. ing.

  When the fuel cell system 10 is in an operating state and the electric roots pump 17 having the above-described configuration is in an operating state, hydrogen off-gas containing water generated in the fuel cell 11 is supplied from an intake port via a conduit 19. The air is sucked into the rotor chamber 24 and discharged out of the rotor chamber 24. Under the low temperature environment, the water condenses on the inner wall surface of the rotor chamber 24 and the wall surfaces of the first rotor 39 and the second rotor 40. Furthermore, when the fuel cell system 10 is stopped from the operating state under freezing and the first rotor 39 and the second rotor 40 are stopped, the water in the rotor chamber 24 is frozen, and the freezing causes the first rotor 39 and the second rotor. Both the front and rear end faces of 40 and the inner wall surface of the rotor chamber 24 are frozen and fixed.

  When restarting the operation of the fuel cell system 10 in the fixed state, when the electric roots pump 17 is started, in the electric motor 41, current is supplied from the external power source to the stator coil 42a to rotate the rotor 43 and at the same time the input shaft 31 is rotated. Simultaneously with the rotation of the input shaft 31, the input gear G rotates. At this time, since the play A between the gear teeth Ga and the first gear teeth G1a is large between the input gear G and the first gear G1, the gear teeth Ga are moved by the amount of play to move the gear teeth Ga to the first gear. It can be made to collide with the tooth G1a. Then, when the gear teeth Ga of the input gear G collide with the first gear teeth G1a of the first gear G1, an impact torque is generated in the first gear G1, and the first rotating shaft 33 is rotated by the impact torque. Can do.

  Due to the generated impact torque, impact torque acts on the first rotor 39 fixed to the first rotating shaft 33, and the impact torque causes the front and rear end surfaces of the first rotor 39 and the inner wall surface of the rotor chamber 24 to be affected. The fixed ice is crushed, the first rotor 39 is peeled off from the inner wall surface of the rotor chamber 24, and the fixed state between the first rotor 39 and the rotor chamber 24 is eliminated. And since the 1st rotor 39 becomes rotatable, the 1st rotating shaft 33 will become rotatable by receiving the rotational torque of the electric motor 41 by receiving the input shaft 31, the input gear G, and the first gear G1.

  Further, the impact torque generated in the first gear G1 is transmitted to the second rotating shaft 35 via the second gear G2. Here, since the backlash between the second gear G2 and the first gear G1 is small and the second gear teeth G2a and the first gear teeth G1a are set so as to mesh quickly, the impact torque is the second gear. It is quickly transmitted from G2 to the second rotating shaft 35. The second rotating shaft 35 can be slightly rotated by the impact torque. Due to the slight rotation of the second rotation shaft 35, the ice that is fixed between the front and rear end faces of the second rotor 40 and the inner wall surface of the rotor chamber 24 is slightly crushed.

  As described above, the first rotating shaft 33 is rotated by receiving the rotating torque of the electric motor 41 via the input gear G and the first gear G1, so that the first rotating shaft 33 rotates. The first rotor 39 also rotates. The rotational torque of the first rotating shaft 33 is transmitted to the second rotating shaft 35 via the second gear G2, and the second rotating shaft 35 rotates. Then, the rotation of the second rotating shaft 35 breaks the ice that adheres between the front and rear end faces of the second rotor 40 and the inner wall surface of the rotor chamber 24, so that the second rotor 40 moves into the rotor chamber 24. While being peeled off from the inner wall surface, the fixed state between the second rotor 40 and the rotor chamber 24 is eliminated.

  And since the 2nd rotor 40 becomes rotatable, the 2nd rotating shaft 35 can rotate by receiving the rotational torque of the electric motor 41 by receiving the input shaft 31, the input gear G, the 1st gear G1, and the 2nd gear G2. It becomes. As a result, the first rotor 39 and the second rotor 40 are rotationally engaged, and the roots pump 17 is operated.

According to the above embodiment, the following effects can be obtained.
(1) In the electric roots type pump 17, the backlash between the input gear G and the first gear G1 is made larger than the backlash between the first gear G1 and the second gear G2. For this reason, when the input gear G meshes with the first gear G1, the gear teeth Ga and the first gear teeth G1a mesh so as to collide, and the impact torque can be generated in the first gear G1 by the collision. The end surface of the first rotor 39 can be peeled off from the inner wall surface of the rotor chamber 24 by rotating the first rotating shaft 33 by this impact torque and applying the impact torque to the first rotor 39. And since the 1st rotating shaft 33 (1st rotor 39) becomes rotatable, it becomes possible to transmit the rotational torque of the electric motor 41 to the 2nd rotating shaft 35, and the 2nd rotating shaft 35 and the 2nd rotor. The end surface of the second rotor 40 can also be peeled off from the inner wall surface of the rotor chamber 24 by rotating the rotor 40.

  Therefore, even when the electric roots pump 17 is started in a state where the first rotor 39 and the second rotor 40 and the rotor chamber 24 are fixed by icing, the first rotor 39 and the first rotor 39 and The second rotor 40 is peeled off from the rotor chamber 24 so that the electric roots pump 17 can be operated. That is, when the electric roots pump 17 is started, it is not necessary to generate a large torque for peeling off the first rotor 39 and the second rotor 40 from the rotor chamber 24. As a result, in the electric roots type pump 17, it is not necessary to mount a large electric motor that generates a large torque in order to peel off the first rotor 39 and the second rotor 40 from the rotor chamber 24. An increase in the size of the pump 17 can be suppressed.

  (2) In the input gear G and the second gear G2 having the same number of gear teeth Ga and G2a, the tooth thicknesses GDa and GDb of the gear teeth Ga are made thinner than the tooth thicknesses G2Da and G2Db of the second gear teeth G2a. Made a difference to the rush. As described above, the first rotor 39 and the second rotor fixed to the inner wall surface of the rotor chamber 24 without increasing the size of the electric roots-type pump 17 only by changing the sizes of the input gear G and the second gear G2. The rotor 40 can be peeled off. Therefore, the manufacturing cost of the electric roots pump 17 can be reduced as compared with the case where the electric motor 41 is enlarged in order to peel off the first rotor 39 and the second rotor 40 fixed to the inner wall surface of the rotor chamber 24. Can do.

  (3) In the electric roots-type pump 17, the backlash between the input gear G to which the rotational torque of the electric motor 41 is first transmitted and the first gear G <b> 1 is increased, and the first rotation is first rotated by the input shaft 31. The shaft 33 was made rotatable first, and then the second rotary shaft 35 was made rotatable. Therefore, for example, the backlash between the second gear G2 and the first gear G1 is made larger than the backlash between the input gear G and the first gear G1, and an impact torque is applied to the second rotating shaft 35. Unlike the case, since the first rotary shaft 33 cannot rotate, the electric Roots pump 17 cannot be operated. Therefore, the configuration in which the backlash between the input gear G and the first gear G1 is larger than the backlash between the second gear G2 and the first gear G1 is the first rotor fixed to the inner wall surface of the rotor chamber 24. This is an optimal configuration for peeling off the 39 and the second rotor 40.

  (4) In the electric roots pump 17, the backlash between the input gear G and the first gear G1 is made larger than the backlash between the second gear G2 and the first gear G1. Here, for example, the backlash between the input gear G and the first gear G1 is made the same as the backlash between the second gear G2 and the first gear G1, and the gear teeth Ga of the input gear G and the first gear G1 It is assumed that one gear tooth G1a is configured to mesh quickly. In this case, since the impact torque is not generated when the input gear G and the first gear G1 mesh with each other, the fixed state of the first rotor 39 is not eliminated, and the first rotating shaft 33 remains unrotatable. Therefore, the electric roots pump 17 cannot be operated. Therefore, by taking a large backlash between the input gear G and the first gear G1, the electric roots pump 17 can be operated without increasing the size of the electric motor 41.

  (5) The input shaft 31 and the second rotating shaft 35 are rotatably connected independently of each other by fitting the connecting member 38 of the second rotating shaft 35 into the connecting hole 31a of the input shaft 31. . Since the input shaft 31 has a long axis shape and is easy to tilt, the connecting member 38 of the second rotating shaft 35 which has a short shaft shape and is not easily tilted is inserted into the connecting hole 31a. By abutting on the peripheral surface of 31a, the inclination of the input shaft 31 and the second rotation shaft 35, in particular, the inclination of the long-axis input shaft 31 can be suitably suppressed.

  (6) The connecting hole 31a and the connecting member 38 are disposed in the gear chamber 26, and lubricating oil is sealed in the gear chamber 26, and between the peripheral surface of the connecting hole 31a and the peripheral surface of the connecting member 38. The lubricating oil has entered. For this reason, even if the input shaft 31 and the 2nd rotating shaft 35 are connected by the connection hole 31a and the connection member 38, abrasion with the connection hole 31a and the connection member 38 is reduced.

In addition, you may change embodiment as follows.
In the embodiment, the connection hole 31a of the input shaft 31 and the connection member 38 of the second rotation shaft 35 may be deleted, and the input shaft 31 and the second rotation shaft 35 may not be connected.

In the embodiment, the connecting member 38 may be provided so as to protrude from the input shaft 31, and the connecting hole 31 a into which the connecting member 38 is inserted may be provided in the second rotating shaft 35.
In the embodiment, energization and de-energization of the stator coil 42a may be repeated a plurality of times, the rotor 43 may be repeatedly rotated, and the gear teeth Ga of the input gear G may be repeatedly collided with the gear teeth Ga of the first gear G1. .

In embodiment, it is good also as the electric roots type pump 17 using the 1st rotor 39 and the 2nd rotor 40 of multileaf form more than three leaves.
In the embodiment, a multi-stage electric roots pump in which a plurality of first rotors 39 and second rotors 40 are attached and fixed in the axial direction of the first rotary shaft 33 and the second rotary shaft 35 may be used.

  In the embodiment, the electric pump is embodied as the electric roots type pump 17 using the first rotor 39 and the second rotor 40 as a rotating body, but the electric pump is changed to an electric screw type pump using a screw rotor as a rotating body. It may be embodied.

The following technical idea (invention) can be understood from the embodiment.
(1) The difference between the backlash between the input gear and the first gear and the backlash between the second gear and the first gear is that the tooth thickness of the gear teeth of the input gear is the tooth thickness of the gear teeth of the second gear. The electric pump for hydrogen circulation as described in any one of Claims 1-3 provided by forming thinner than thickness.

The longitudinal section showing the electric roots type pump of an embodiment. The expanded sectional view which shows the meshing state of a 1st gear and a 2nd gear. The expanded sectional view which shows the meshing state of an input gear and a 1st gear. The block diagram of a fuel cell system.

Explanation of symbols

  G ... input gear, G1 ... first gear, G2 ... second gear, M ... motor housing constituting the housing, P ... pump housing constituting the housing, 10 ... fuel cell system, 11 ... fuel cell, 17 ... hydrogen circulation Electric root pump as a hydrogen circulation electric pump constituting the path, 18, 19 ... Pipe lines constituting the hydrogen circulation path, 20 ... Hydrogen tank as a hydrogen source, 24 ... Rotor chamber as a pump chamber, 26 ... Gear Chamber 31... Input shaft 31 a. Connecting hole 33. First rotating shaft 35. Second rotating shaft 38. Connecting member 39 39 First rotor as one rotating body 40. 2nd rotor, 41 ... electric motor.

Claims (3)

For hydrogen circulation that constitutes the hydrogen circulation path of the fuel cell system having a hydrogen circulation path that can supply hydrogen gas that has not been used in the fuel cell to hydrogen gas supplied from a hydrogen source to supply the fuel cell An electric pump,
An electric motor is accommodated in the housing and a pump chamber is formed. A pair of rotating bodies that rotate as the electric motor rotates are accommodated in the pump chamber. An input shaft provided with a gear and rotated by the electric motor, and a first gear arranged in parallel to the input shaft and meshingly connected to the input gear, and one of the pair of rotating bodies is A fixed first rotating shaft and a second rotating shaft that is disposed coaxially with the input shaft and has a second gear meshingly connected to the first gear and to which the other rotating body is fixed are rotatable. And the backlash between the input gear and the first gear is made larger than the backlash between the second gear and the first gear. . The input shaft and the second rotating shaft are rotatably connected independently of each other by inserting a connecting member provided on the other shaft into a connecting hole provided on one of the shafts. The electric pump for hydrogen circulation according to claim 1. The input gear, the first gear, and the second gear are accommodated and disposed in a gear chamber formed in the housing, and the coupling hole and the coupling member are disposed in the gear chamber. Electric pump for hydrogen circulation.

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