JP2007198216A - Electric pump for hydrogen circulation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric pump for hydrogen circulation enabling a rotor adhered to a pump case to be peeled off while suppressing enlargement. <P>SOLUTION: This electric Roots pump 17 is vertically disposed so that a drive shaft 31 and a driven shaft 35 extend in the direction of the gravity and a drive rotor 39, a driven rotor 40, and an electric motor 41 are arranged in the direction of the gravity. The electric motor 41 comprises a stator 42 and a motor rotor 43. The motor rotor 43 is installed on the outer peripheral side of the drive shaft 31. The motor rotor 43 is installed movably along the drive shaft 31. A support member 46 for supporting the motor rotor 43 is installed on the drive shaft 31 at the position where the magnetic center of the motor rotor 43 is displaced downward from the magnetic center of stator 42. Also, a stopper 48 is fitted to the drive shaft 31 for making impact the first end face 43b of the motor rotor 43 therewith when the magnetic centers of the stator 42 and the motor rotor 43 are aligned with each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric pump for hydrogen circulation in which a rotating shaft extends in a gravitational direction and is arranged vertically so that a rotating body and an electric motor are arranged in the gravitational direction.

  As a pump used for fuel supply of an automobile, for example, a fluid pump disclosed in Patent Document 1 can be cited. This fluid pump has a motor part and a pump part, and the motor part has a pair of magnets fixed to the inner peripheral surface of the motor housing, and an armature rotatably arranged in the magnets. The armature includes a shaft, a core composed of a core sheet and a winding coil attached to the shaft, and a commutator provided adjacent to the core.

The pump unit includes an impeller mounted on an end opposite to the commutator across the core of the armature shaft, and rotatably accommodates the impeller, and defines an annular fluid flow path between the impeller and the impeller. It has a pump housing. The pump housing is formed with a pump chamber for rotatably housing the impeller. The motor unit and the pump unit are disposed in the fuel tank of the automobile so as to be in series in the direction of gravity (vertical direction). In the fluid pump, the armature is disposed such that the center line of the core is shifted to the pump part side by a predetermined amount with respect to the center line of the magnet. By arranging the core and the magnet so as to be shifted from each other, it is possible to generate an upward magnetic attractive force that is opposite to the direction of gravity, that is, opposite to the direction of the weight of the armature. Then, by adjusting the amount of deviation between the center lines, the armature is prevented from moving upward even when an upward magnetic attraction force is generated, the tip of the shaft integral with the armature, and the bottom of the shaft hole It is possible to prevent the wear of both of them.
Japanese Patent Laid-Open No. 62-159779

  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. This hydrogen circulation path is provided with a pump for transporting hydrogen off-gas.

  When the fluid pump disclosed in Patent Document 1 is used as the pump, the pump unit operates as the motor unit rotates, and hydrogen off-gas is sucked into the pump chamber. Furthermore, the hydrogen off-gas is mixed with the newly supplied hydrogen gas by the operation of the pump unit, so that the fuel cell is re-supplied.

  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. The fluid pump is disposed in the fuel cell vehicle such that the motor part and the pump part are in series in the direction of gravity (vertical direction). For this reason, the water introduced into the pump chamber remains in the bottom of the pump chamber. Here, for example, when the fuel cell system is stopped from the operating state in a low temperature environment such as below freezing point, water accumulated in the bottom of the pump chamber is condensed and frozen, and the lower surface of the impeller and the bottom surface of the pump chamber are It freezes and sticks. When the lower surface of the impeller and the bottom surface of the pump chamber are fixed, the impeller is peeled off from the bottom 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 motor portion of the fluid pump. As a result, in the fluid pump, it is necessary to provide a large motor unit that can generate a large torque at the time of startup, which increases the size of the body.

  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 a pump chamber is defined in the housing and an electric motor is accommodated, and further, the electric motor is accommodated in the housing. A rotating shaft that can be rotated by a motor is supported, and a rotating body that rotates as the rotating shaft rotates is accommodated in the pump chamber. The rotating shaft extends in the direction of gravity. An electric pump for circulating hydrogen vertically arranged so that the motors are arranged in the direction of gravity, wherein the electric motor is rotatable relative to the stator and the stator And the motor rotor is provided on the outer peripheral side of the rotating shaft so as to be movable in the axial direction of the rotating shaft, and the rotating shaft has a magnetic center of the motor rotor with respect to a magnetic center of the stator. Is provided with a support member for supporting the motor rotor at a position shifted downward, and a collision member is provided for colliding the upper end surface of the motor rotor when the magnetic centers of the stator and the motor rotor coincide with each other. .

  According to this configuration, at the time of starting the hydrogen circulation electric pump in a state where the rotating body and the pump chamber are fixed by freezing, the stator is driven by the magnetic force generated between the stator and the motor rotor when the electric motor is started. The motor rotor moves upward in the weight direction along the axial direction of the rotary shaft so that the magnetic center of the motor and the magnetic center of the motor rotor coincide with each other. During the movement of the motor rotor, the upper end surface of the motor rotor collides with the collision member provided on the rotating shaft from below. At this time, an upward load along the axial direction acts on the rotating shaft due to the collision from the lower side, and an upward load acts on the rotating body via the rotating shaft. Can be peeled off. Therefore, when the hydrogen circulation electric pump is started with the rotating body and the pump chamber fixed by icing, the rotating body can be peeled off from the pump chamber only by starting the electric motor, and the fixed rotating body can be rotated. Therefore, it is not necessary to generate a large torque in the electric motor.

  Further, in a state where the motor rotor is supported by the support member, the collision member may be provided below the upper end surface of the motor rotor when the magnetic centers of the stator and the motor rotor coincide.

  According to this configuration, when the motor rotor moves upward along the axial direction of the rotating shaft, the upper end surface of the motor rotor collides with the collision member immediately before the magnetic centers of the stator and the motor rotor coincide with each other. When the target center coincides, the rotating shaft is pushed upward by the motor rotor via the collision member. Therefore, the rotating body is moved upward by the load generated by the collision and the motor rotor being pushed up, and the rotating body is moved upward via the rotating shaft, so that the rotating body can be reliably peeled off from the pump chamber. it can.

  The housing is provided with a radial bearing that rotatably supports the rotating shaft, and the radial bearing is disposed outside the inner ring and fixed to the rotating shaft so as to rotate integrally therewith. And the rolling element interposed between the inner ring and the outer ring, and when the motor rotor collides with the collision member, the rotation shaft moves upward by an allowable movement amount of the inner ring with respect to the outer ring. It may be moved.

  According to this configuration, the push-up amount (movement amount) of the rotating shaft by the motor rotor is an allowable movement amount (shaking amount) of the inner ring with respect to the outer ring in the radial bearing. That is, when the rotation shaft moves by an amount that allows the inner ring to move with respect to the outer ring, the upward movement of the rotation shaft can be restricted. Therefore, it is possible to regulate the amount of movement of the rotating shaft using a radial bearing having an existing configuration.

Further, the rotating body may be a pair of rotors that can mesh with each other, and the electric pump for hydrogen circulation may be a Roots type pump.
According to this configuration, when the electric pump for hydrogen circulation is installed vertically, the end surfaces of the pair of rotors face the inner wall surface of the pump chamber, and each rotor is placed inside the pump chamber by freezing of water introduced into the pump chamber. It becomes easy to adhere to the wall. However, by adopting a configuration in which the motor rotor collides with the collision member as in the present invention, each rotor can be reliably peeled off from the inner wall surface of the pump chamber. Therefore, the configuration in which the support member and the collision member are provided on the rotation shaft and the motor rotor is mounted so as to be movable along the rotation shaft is particularly effective for use in a Roots pump.

  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.

(First embodiment)
A first embodiment in which the electric pump for circulating hydrogen of the present invention is embodied as an electric roots pump used as a hydrogen circulating pump in a fuel cell system mounted on a fuel cell vehicle will be described with reference to FIGS. To do. 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 includes an electric roots pump 17 for circulating and using hydrogen gas (so-called hydrogen off gas) that has not been used in the fuel cell 11. 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 of the first embodiment, “upper” and “lower” of the electric roots pump 17 have the direction of the arrow Y shown in FIG. 1 as the vertical (gravity) direction. The electric roots pump 17 has a drive shaft 31 as a rotating shaft extending in the direction of gravity (vertical direction) when mounted on a fuel cell vehicle.

  As shown in FIG. 1, the housing of the electric roots type pump 17 of this embodiment is composed of a pump housing P and a motor housing M. The electric roots pump 17 is used as a vertical type in which both housings P and M are arranged in the gravitational direction (vertical direction) so that the pump housing P is positioned above the motor housing M in the gravitational direction. It is done. The pump housing P is joined and fixed to the gear housing 25 joined and fixed to the upper end of the motor housing M, the shaft support member 23 joined and fixed to the upper end of the gear housing 25, and the upper end of the shaft support member 23. And the rotor housing 22. 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. In the rotor chamber 24, the wall surface of the rotor chamber 24 formed by the rotor housing 22 is an inner wall surface 22H, and the wall surface of the rotor chamber 24 formed by the shaft support member 23 is an inner wall surface 23H. A gear chamber 26 is enclosed between the gear housing 25 and the shaft support member 23. Further, 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.

  In the housing configured as described above, the motor housing M, the rotor housing 22 and the shaft support member 23 are rotatably supported by a drive shaft 31 as a rotation shaft via a radial bearing 32. The radial bearing 32 is fixed to the peripheral surface 31a of the drive shaft 31, and an inner ring 32a that can rotate integrally with the drive shaft 31, an outer ring 32b disposed on the outer peripheral side of the inner ring 32a, and the outer ring 32b. And a rolling element 32c interposed between the inner ring 32a and the inner ring 32a. In the housing configured as described above, a driven shaft 35 that is parallel to the drive shaft 31 is rotatably supported by the rotor housing 22 and the shaft support member 23 via a radial bearing 36. The radial bearing 36 is fixed to the peripheral surface 35a of the driven shaft 35, and an inner ring 36a that can rotate integrally with the driven shaft 35, an outer ring 36b disposed on the outer peripheral side of the inner ring 36a, and the outer ring 36b. And a rolling element 36c interposed between the inner ring 36a and the inner ring 36a.

  In the rotor chamber 24, a driving rotor 39 as a rotating body is attached and fixed to the driving shaft 31, and a driven rotor 40 as a rotating body is attached and fixed to the driven shaft 35. In the electric roots type pump 17 of the first embodiment, the drive shaft 31 extends in the direction of gravity (vertical direction), and the drive rotor 39 and the driven rotor 40 (upper side) and the electric motor 41 (lower side) are connected. They are placed vertically so as to be arranged in the gravitational direction (vertical direction). In the drive rotor 39, the direction along the axial direction of the drive shaft 31 (vertical direction in FIG. 1) is the axial direction of the drive rotor 39, and in the driven rotor 40, the direction along the axial direction of the driven shaft 35 (vertical direction in FIG. Direction) is the axial direction of the driven rotor 40. The drive rotor 39 and the driven rotor 40 are two-leaf type rotors that are formed in a double-leaf shape (saddle shape) in a cross-sectional view orthogonal to the axial direction of the drive shaft 31 and the driven shaft 35, and are formed so as to be able to mesh with each other. Yes. Here, of the end surfaces in the axial direction of the drive rotor 39 and the driven rotor 40, end surfaces (upper end surfaces) opposite to the inner wall surface 22 </ b> H of the rotor housing 22 are first rotor end surfaces 39 a and 40 a, and the shaft support member 23. End surfaces (lower end surfaces) opposite to the inner wall surface 23H are defined as second rotor end surfaces 39b and 40b.

  A clearance CL is formed between the first rotor end surfaces 39a, 40a and the inner wall surface 22H of the rotor chamber 24 in a state where the electric roots type pump 17 is installed vertically and no electric current is supplied to the electric motor 41, A clearance (not shown) is formed between the second rotor end faces 39 b and 40 b and the inner wall surface 23 </ b> H of the rotor chamber 24. When the electric motor 41 is not energized, the clearance CL formed between the first rotor end surfaces 39a and 40a and the inner wall surface 22H is formed between the second rotor end surfaces 39b and 40b and the inner wall surface 23H. Is larger than clearance.

  The rotor housing 22 has a suction port (not shown) for sucking the 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. ) Is formed. In the gear chamber 26, the drive gear 37 fixed to the drive shaft 31 and the driven gear 38 fixed to the driven shaft 35 are meshed and connected.

  In the fuel cell system 10 including the electric roots pump 17 configured as described above, when the drive shaft 31 is rotated based on the rotational drive of the electric motor 41, the driven shaft 35 is engaged with the drive gear 37 and the driven gear 38 through meshing connection. It rotates in a direction different from that of the drive shaft 31. Then, in the rotor chamber 24, the drive rotor 39 and the driven rotor 40 rotate. 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 drive rotor 39 and the driven rotor 40 rotate. Thereafter, as the drive rotor 39 and the driven rotor 40 rotate, the hydrogen off-gas sucked into the rotor chamber 24 is sent to the discharge port side of the rotor chamber 24 and discharged from the discharge port to the pipe line 18 outside the rotor chamber 24. Is done. 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 electric motor 41 and the drive shaft 31 will be described in detail.
As shown in FIG. 1, the electric motor 41 includes a stator 42 fixed to the inner surface of the motor housing M, a motor rotor that is disposed inside the stator 42 and that can rotate relative to the stator 42 in both forward and reverse directions. 43. 1 is defined as the magnetic center of the stator 42, and the alternate long and short dash line J2 is defined as the magnetic center of the motor rotor 43. 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 motor rotor 43 is formed in a cylindrical shape, and the motor rotor 43 is mounted on the outer peripheral side of the drive shaft 31. Here, in the motor rotor 43, the end surface (upper end surface) on the gear housing 25 side along the axial direction of the drive shaft 31 is a first end surface 43b, and the end surface (lower end surface) opposite to the first end surface 43b is a first end surface. Let it be the 2 end surface 43c.

  Since the drive shaft 31 is rotatably supported by the housing by the bearing 32, the drive shaft 31 is interposed between the peripheral surface 31a of the drive shaft 31 and the inner peripheral surface 43a of the motor rotor 43 facing the peripheral surface 31a. A very small clearance is formed. A key groove 31 b that extends linearly along the axial direction of the drive shaft 31 is recessed in the peripheral surface 31 a of the drive shaft 31 that faces the inner peripheral surface 43 a of the motor rotor 43. The key groove 31b is press-fitted into one side of a key 45 having an elongated plate shape. The key 45 is integrated with the drive shaft 31 and can rotate integrally with the drive shaft 31.

  On the inner peripheral surface 43a of the motor rotor 43 facing the peripheral surface 31a of the drive shaft 31, an insertion groove 47 into which the other side portion of the key 45 is inserted is recessed at a position facing the key 45. As the motor rotor 43 rotates, the inner surface of the insertion groove 47 contacts the key 45 so that the rotational torque of the motor rotor 43 is transmitted to the drive shaft 31 via the key 45. The motor rotor 43 is attached to the drive shaft 31 so as to be movable along the axial direction of the drive shaft 31 with the insertion groove 47 as a guide. When the electric motor 41 is energized, as shown in FIG. 2, the motor rotor 43 rotates in a state where the magnetic center of the stator 42 and the magnetic center of the motor rotor 43 coincide with each other, and the rotational torque of the motor rotor 43 is increased. The drive shaft 31 is rotated by being transmitted to the drive shaft 31 via the key 45.

  As shown in FIG. 1, a support member 46 is mounted on the peripheral surface 31 a of the drive shaft 31 at a position below the motor rotor 43. The support member 46 is provided over the entire circumference of the drive shaft 31 in the circumferential direction. The support member 46 contacts the second end surface 43c of the motor rotor 43 in a state where the motor rotor 43 is displaced downward so that the magnetic center of the stator 42 is positioned below the magnetic center of the motor rotor 43, The motor rotor 43 is supported. The support member 46 can apply a magnetic force between the stator 42 and the motor rotor 43 when the electric motor 41 is energized even if the magnetic center of the motor rotor 43 is shifted downward from the magnetic center of the stator 42. The motor rotor 43 is supported at a possible position.

  A stopper 48 as a collision member is attached to a position above the motor rotor 43 on the peripheral surface 31 a of the drive shaft 31. The stopper 48 is provided over the entire circumference of the drive shaft 31 in the circumferential direction. In the state where the motor rotor 43 is supported by the support member 46, the stopper 48 is mounted on the peripheral surface 31 a of the drive shaft 31 so that the upper surface 48 a thereof is located on the same plane as the upper surface 42 b of the stator 42. . That is, in a state where the motor rotor 43 is supported by the support member 46, the stopper 48 is provided below the first end surface 43b which is the upper end surface of the motor rotor 43 when the magnetic centers of the stator 42 and the motor rotor 43 coincide. ing.

  When the electric motor 41 is energized while the motor rotor 43 is supported by the support member 46, an upward magnetic force acts on the motor rotor 43, and the magnetic center of the stator 42 and the magnetic center of the motor rotor 43 are separated. The motor rotor 43 moves upward so as to match. When the motor rotor 43 moves upward, the first end surface 43b, which is the upper end surface of the motor rotor 43, collides with the lower surface 48b of the stopper 48, and an upward load acts on the stopper 48.

  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. It is sucked into the rotor chamber 24 and discharged out of the rotor chamber 24 through the discharge port. The water sucked into the rotor chamber 24 is condensed in a low temperature environment, and further flows down toward the inner wall surface 23H on the bottom side of the rotor chamber 24 by its own weight, and the inner wall surface 23H, the drive rotor 39, and the follower are driven. It accumulates between the second rotor end faces 39b, 40b of the rotor 40. Further, the water sucked into the rotor chamber 24 is also condensed on the wall surfaces of the drive rotor 39 and the driven rotor 40 in a low temperature environment. When the fuel cell system 10 is stopped from the operating state below the freezing point and the drive rotor 39 and the driven rotor 40 are stopped, the water in the rotor chamber 24 is frozen. Due to the freezing, the second rotor end faces 39b, 40b of the drive rotor 39 and the driven rotor 40 and the inner wall surface 23H of the rotor chamber 24 are frozen and fixed, and the wall surfaces of the drive rotor 39 and the driven rotor 40 are fixed to each other. It becomes a state.

  When restarting the operation of the fuel cell system 10 in the above-mentioned fixed state, the electric roots pump 17 is activated, and in the electric motor 41, a current is passed from the external power source to the stator coil 42a. An upward magnetic force (thrust) is generated in the motor rotor 43 so as to coincide with the center. Then, the motor rotor 43 moves upward along the drive shaft 31 while using the key 45 as a guide. Here, the stopper 48 is provided below the position where the first end face 43b of the motor rotor 43 is located when the magnetic center of the stator 42 and the magnetic center of the motor rotor 43 coincide. Therefore, the first end surface 43 b of the motor rotor 43 that moves upward collides with the lower surface 48 b of the stopper 48. Due to this collision, an upward load acts on the stopper 48, and an upward load along the axial direction also acts on the drive shaft 31. Further, since the motor rotor 43 moves to a position where the magnetic center thereof coincides with the magnetic center of the stator 42, the drive shaft 31 moves from the position shown by the two-dot chain line in FIG. 2 to the position shown by the solid line. It is pushed up by the motor rotor 43.

  That is, the drive shaft 31 on which the stopper 48 is mounted moves slightly upward as the motor rotor 43 is pushed up in addition to the upward load. As shown in FIG. 3, the movement amount of the drive shaft 31 is an allowable movement amount of the inner ring 32 a fixed to the drive shaft 31 with respect to the outer ring 32 b. That is, the drive shaft 31 is movable by an amount of shakiness between the inner ring 32a and the outer ring 32b in the axial direction of the drive shaft 31 of the inner ring 32a. When the drive shaft 31 moves upward by the upward load and push-up, an upward load acts on the drive rotor 39 provided on the drive shaft 31. Here, since the clearance CL is formed between the first rotor end surface 39a of the drive rotor 39 and the inner wall surface 22H of the rotor chamber 24 (see FIG. 1), the clearance of the drive rotor 39 is within the clearance CL. An upward movement is allowed. Then, the second rotor end surface 39 b of the drive rotor 39 is peeled off from the inner wall surface 23 </ b> H of the rotor chamber 24.

  At this time, since the wall surface of the driven rotor 40 is fixed to the drive rotor 39, the driven rotor 40 is pushed up at the same time as the drive rotor 39 is pushed up. The amount of movement of the driven shaft 35 is also an allowable movement amount of the inner ring 36a fixed to the driven shaft 35 with respect to the outer ring 36b. That is, the driven shaft 35 is movable by the amount of shakiness in the axial direction of the driven shaft 35 that exists between the inner ring 36a and the outer ring 36b. The second rotor end surface 39b of the drive rotor 39 is peeled off from the inner wall surface 23H, and at the same time, the second rotor end surface 40b of the driven rotor 40 is also peeled off from the inner wall surface 23H. As a result, the fixed state of the drive rotor 39 and the driven rotor 40 and the rotor chamber 24 is eliminated.

  Then, after the drive rotor 39 and the driven rotor 40 are peeled off from the rotor chamber 24, the rotation of the motor rotor 43 is transmitted to the drive shaft 31 by the contact of the motor rotor 43 with the key 45, and the electric roots pump 17 is operated. Is done.

According to the above embodiment, the following effects can be obtained.
(1) In the vertical electric roots type pump 17, the magnetic center of the motor rotor 43 is shifted downward with respect to the magnetic center of the stator 42 by the support member 46 provided on the drive shaft 31 extending in the gravitational direction (vertical direction). The motor rotor 43 was supported at this position. Further, the first end surface (upper end surface) 43b of the motor rotor 43 collides with the drive shaft 31 when the motor rotor 43 moves upward so that the magnetic center of the stator 42 and the magnetic center of the motor rotor 43 coincide. A stopper (collision member) 48 is provided. Then, when the electric motor 41 is started, an upward load is applied to the drive shaft 31 by a load generated when the motor rotor 43 collides with the stopper 48, and an upward load is applied to the drive rotor 39 fixed to the drive shaft 31. Can act. As a result, the frozen second rotor end surface 39b of the drive rotor 39 and the inner wall surface 23H of the rotor chamber 24 can be peeled off, and the driven rotor 40 can be peeled off from the inner wall surface 23H of the rotor chamber 24 simultaneously with the drive rotor 39. Can do.

  Therefore, when the electric roots pump 17 is started, the electric motor 41 is started and the motor rotor 43 is moved along the drive shaft 31, so that the drive rotor 39 and the driven rotor 40 fixed to the inner wall surface 23 </ b> H of the rotor chamber 24 are moved. It can be peeled off from the inner wall surface 23H. That is, when the electric roots pump 17 is started, it is not necessary to generate a large torque for peeling from the rotor chamber 24 by rotating the drive rotor 39 and the driven rotor 40. 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 separate the drive rotor 39 and the driven rotor 40 from the rotor chamber 24, and the electric roots type pump 17. Can be prevented from increasing in size.

  (2) In a state where the motor rotor 43 is supported by the support member 46, the stopper 48 is below the position of the first end face 43b of the motor rotor 43 located when the magnetic centers of the stator 42 and the motor rotor 43 coincide. . For this reason, when the motor rotor 43 moves upward by the upward magnetic force, the first end face 43b of the motor rotor 43 collides with the stopper 48 immediately before the magnetic centers coincide with each other, and when the magnetic centers coincide with each other. In this case, the drive shaft 31 is pushed upward by the motor rotor 43 via the stopper 48. Therefore, the drive shaft 31 can be moved upward by the load generated by the collision and the motor rotor 43 being pushed up, and the second rotor end surfaces 39b and 40b of the drive rotor 39 and the driven rotor 40 are connected to the inner wall surface 23H of the rotor chamber 24. Can be reliably peeled off.

  (3) The amount (movement amount) by which the drive shaft 31 is pushed up is an allowable movement amount (rattle amount) of the inner ring 32a with respect to the outer ring 32b in the radial bearing 32. Therefore, the movement amount of the drive shaft 31 can be regulated using the radial bearing 32 having an existing configuration. For example, an electric roots type pump can be used as compared with a case where a means for regulating the movement amount of the drive shaft 31 is separately provided. It is possible to prevent the configuration of 17 from becoming complicated.

  (4) The electric roots type pump 17 is a type using the drive rotor 39 and the driven rotor 40 as the rotating body. However, when the electric roots type pump 17 is placed vertically, the driving rotor 39 and the second rotor of the driven rotor 40 are used. The end surfaces 39b and 40b face the inner wall surface 23H of the rotor chamber 24, and the drive rotor 39 and the driven rotor 40 are easily fixed to the inner wall surface 23H. However, by making the motor rotor 43 collide with the stopper 48, the drive rotor 39 and the driven rotor 40 can be reliably peeled off from the inner wall surface 23H. Therefore, the structure in which the support member 46 and the stopper 48 are provided on the drive shaft 31 and the motor rotor 43 is mounted so as to be movable along the drive shaft 31 is particularly effective for use in a roots type electric pump.

(Second Embodiment)
Next, a second 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 mounted on a fuel cell vehicle according to FIGS. 5 and 6. explain. Note that in the second embodiment described below, the same components as those in the first embodiment described above are denoted by the same reference numerals, and redundant description thereof is omitted or simplified. In the following description of the second embodiment, “upper” and “lower” of the electric roots pump 17 have the direction of the arrow Y shown in FIG. 5 as the vertical (gravity) direction. The electric roots pump 17 has a drive shaft 31 as a rotating shaft extending in the direction of gravity (vertical direction) when mounted on a fuel cell vehicle.

  As shown in FIG. 5, in the electric roots type pump 17 of the second embodiment, both the housings M, P are in the gravity direction (up and down) so that the motor housing M is located above the pump housing P in the gravity direction. Used as a vertical type arranged in the direction). That is, the electric Roots type pump 17 of the second embodiment is placed vertically with the electric pump 41 (upper side), the drive rotor 39 and the driven rotor 40 (lower side) in a vertically inverted state with respect to the first embodiment. Are vertically arranged so as to be arranged in the vertical direction. In the state where the electric Roots pump 17 is installed vertically, there is a very slight clearance between the first rotor end surfaces 39a, 40a, which are the lower end surfaces of the drive rotor 39 and the driven rotor 40, and the inner wall surface 22H of the rotor chamber 24. Formed (not shown). Further, a clearance CL is formed between the second rotor end surfaces 39 b and 40 b that are upper end surfaces of the drive rotor 39 and the driven rotor 40 and the inner wall surface 23 </ b> H of the rotor chamber 24. In the vertically placed state of the electric roots pump 17, the clearance CL formed between the second rotor end surfaces 39b and 40b and the inner wall surface 23H is between the first rotor end surfaces 39a and 40a and the inner wall surface 22H. It is larger than the clearance formed.

  Further, on the peripheral surface 31 a of the drive shaft 31, the support member 46 is mounted at a position below the motor rotor 43, and a stopper 48 is mounted at a position above the motor rotor 43. For this reason, the motor rotor 43 is supported by the support member 46 when the first end face 43 b abuts on the support member 46. Further, when an upward magnetic force is applied to the motor rotor 43 and the motor rotor 43 moves upward, the second end surface 43 c serving as the upper end surface of the motor rotor 43 collides with the stopper 48.

  Also in the electric roots type pump 17 of the second embodiment, as shown in FIG. 6, when the electric motor 41 is started, the second end face 43 c of the motor rotor 43 collides with the stopper 48 and is generated at the time of the collision. The upward load can be applied to the drive shaft 31 by the load to be pushed and the motor rotor 43 being pushed up. As a result, an upward load also acts on the drive rotor 39 and the driven rotor 40, and the drive rotor 39 and the driven rotor 40 are pulled up. Therefore, even if the first rotor end surfaces 39a and 40a are fixed to the inner wall surface 22H due to freezing of water in the rotor chamber 24, the first rotor end surfaces 39a and 40a are pulled up by pulling up the drive rotor 39 and the driven rotor 40. It can be peeled off from the inner wall surface 22H. That is, even if the electric roots type pump 17 is upside down with respect to the first embodiment, the same effects as (1) to (4) of the first embodiment can be exhibited.

Each embodiment may be changed as follows.
In each embodiment, energization and de-energization of the electric motor 41 may be repeated a plurality of times, the motor rotor 43 may be repeatedly moved in the direction of gravity (vertical direction), and the motor rotor 43 may be repeatedly collided with the stopper 48.

In each embodiment, it is good also as the electric roots type pump 17 using the multi-leaf-like drive rotor 39 and the driven rotor 40 of three or more leaves.
In each embodiment, a multistage electric roots pump in which a plurality of drive rotors 39 and driven rotors 40 are attached and fixed in the axial direction of the drive shaft 31 and the driven shaft 35 may be used.

  In each embodiment, the electric pump for circulating hydrogen is embodied in the electric roots pump 17 having the drive rotor 39 and the driven rotor 40 as rotating bodies, but the electric pump is an electric screw pump having a screw as a rotating body. It may be embodied in.

  In the first embodiment, the first rotor end surfaces 39a and 40a of the drive rotor 39 and the driven rotor 40 are brought into contact with the inner wall surface 22H of the rotor chamber 24 to restrict the upward movement amount of the drive shaft 31. It is good. In this case, the clearance CL between the first rotor end faces 39a, 40a of the drive rotor 39 and the driven rotor 40 and the inner wall surface 22H of the rotor chamber 24 is an allowable movement amount (backlash) of the inner ring 32a with respect to the outer ring 32b in the radial bearing 32. Less than the amount). In the second embodiment, the amount of upward movement of the drive shaft 31 is restricted by bringing the second rotor end faces 39b, 40b of the drive rotor 39 and the driven rotor 40 into contact with the inner wall surface 23H of the rotor chamber 24. It is good also as a structure. In this case, the clearance CL between the second rotor end surfaces 39b, 40b of the drive rotor 39 and the driven rotor 40 and the inner wall surface 23H of the rotor chamber 24 is an allowable movement amount (backlash) of the inner ring 32a with respect to the outer ring 32b in the radial bearing 32. Less than the amount).

  In each embodiment, the inner ring 32 a of the radial bearing 32 may not be fixed to the drive shaft 31 so as to be integrally rotatable. In this case, when the electric motor 41 is energized, a force acts in a direction in which the magnetic center of the stator 42 matches the magnetic center of the motor rotor 43. For this reason, even if the magnetic center of the motor rotor 43 exceeds the magnetic center of the stator 42 at the time of startup and the motor rotor 43 moves upward, the amount of movement of the drive shaft 31 is restricted by the restoring force that makes both magnetic centers coincide. Is done.

The longitudinal section showing the electric roots type pump of a 1st embodiment. The longitudinal cross-sectional view which shows an electric roots type pump when the magnetic center of a stator and a motor rotor corresponds. The expanded sectional view which shows the state which the drive shaft and the drive rotor moved upwards. The block diagram of a fuel cell system. The longitudinal cross-sectional view which shows the electric roots type pump of 2nd Embodiment. The longitudinal cross-sectional view which shows an electric roots type pump when the magnetic center of a stator and a motor rotor corresponds.

Explanation of symbols

  M: motor housing constituting the housing, P: pump housing constituting the housing, 10 ... fuel cell system, 11 ... fuel cell, 17 ... electric roots pump as an electric pump for hydrogen circulation constituting the hydrogen circulation path, 18 , 19 ... Pipes constituting a hydrogen circulation path, 20 ... Hydrogen tank as a hydrogen source, 24 ... Rotor chamber as a pump chamber, 31 ... Drive shaft as a rotating shaft, 32 ... Radial bearing, 32a ... Inner ring, 32b ... Outer ring, 32c ... rolling element, 39 ... driving rotor as rotating body, 40 ... driven rotor as rotating body, 41 ... electric motor, 42 ... stator, 43 ... motor rotor, 43b ... first end face as upper end face, 43c ... a second end face as an upper end face, 46 ... a support member, 48 ... a stopper as a collision member.

Claims (4)

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, in which a pump chamber is defined in the housing and an electric motor is accommodated; and a rotary shaft that is rotatable by the electric motor is supported in the housing; Contains a rotating body that rotates as the rotating shaft rotates, and the rotating shaft extends in the direction of gravity, and the rotating body and the electric motor are arranged vertically so that they are arranged in the direction of gravity. An electric pump,
The electric motor includes a stator and a motor rotor that can rotate relative to the stator. The motor rotor is provided on an outer peripheral side of the rotating shaft so as to be movable in an axial direction of the rotating shaft. When a support member for supporting the motor rotor is provided at a position where the magnetic center of the motor rotor is shifted downward with respect to the magnetic center of the stator, and when the magnetic centers of the stator and the motor rotor coincide with each other, An electric pump for hydrogen circulation, wherein a collision member that collides with an upper end surface of the motor rotor is provided. 2. The hydrogen according to claim 1, wherein in a state where the motor rotor is supported by the support member, the collision member is provided below the upper end surface of the motor rotor when the magnetic centers of the stator and the motor rotor coincide with each other. Electric pump for circulation. The housing is provided with a radial bearing that rotatably supports the rotating shaft, and the radial bearing is disposed outside the inner ring and fixed to the rotating shaft so as to rotate integrally therewith. An outer ring and a rolling element interposed between the inner ring and the outer ring. When the motor rotor collides with the collision member, the rotation shaft is moved upward by an allowable movement amount of the inner ring with respect to the outer ring. The electric pump for hydrogen circulation according to claim 2. 4. The hydrogen circulation electric pump according to claim 1, wherein the rotating body is a pair of rotors that can mesh with each other, and the hydrogen circulation electric pump is a Roots type pump. 5.

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