JP2007270678A - Electric gear pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric gear pump capable of reducing manufacturing cost, by simplifying a structure and a manufacturing process. <P>SOLUTION: This electric gear pump 10 has a pump part 30 provided with an outer rotor 31 having internal teeth 31b, an inner rotor 33 having external teeth 33a meshing with the internal teeth 31b, and a housing 11 storing both these rotors 31 and 33, and a motor part 20 having a driving shaft 26 rotatingly driving the pump part 30. The driving shaft 26 is supported so that one end part 26a is formed as the free end and the other end part is coaxially integrally rotatable with the outer rotor 31. A ball bearing 32 rotatably supporting the outer rotor 31 to the housing 11, is interposed between the outer rotor 31 and the housing 11. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric gear pump used for, for example, a pump for pumping hydraulic oil of an automobile transmission.

  2. Description of the Related Art Conventionally, as a pump for pumping hydraulic oil in a transmission such as an automobile, an electric gear pump that rotates an internal gear pump such as a trochoid pump with a motor is used. The electric gear pump includes a motor, an inner rotor that is rotationally driven by the motor and has external teeth, an outer rotor having internal teeth that mesh with the external teeth, and the outer rotor inserted into the outer rotor. And a rotor housing that is rotatably accommodated. This outer rotor meshes with the outer teeth of the inner rotor whose inner teeth are rotationally driven, and is configured to rotate on the inner peripheral side of the rotor housing (see, for example, Patent Document 1).

JP 2004-204694 A (FIGS. 1 and 2)

In the conventional electric gear pump, the drive shaft of the motor and the rotating shaft of the inner rotor are integrally formed, and both ends of the drive shaft are supported by rolling bearings. Further, the outer peripheral surface of the outer rotor and the inner peripheral surface of the rotor housing constitute a sliding bearing, and the rotor housing rotatably supports the outer rotor by the sliding bearing. As described above, the conventional electric gear pump requires a large number of bearings to support the motor and both rotors.
Since a large number of bearings are arranged as described above, the internal structure of the electric gear pump is complicated, and as a result, many steps are required even when the electric gear pump is assembled, and the manufacturing cost increases. Had the problem.
This invention is made | formed in view of such a situation, and it aims at providing the electric gear pump which can simplify a structure and a manufacturing process and can reduce manufacturing cost.

  The present invention relates to a motor including an outer rotor having internal teeth, an inner rotor having external teeth meshing with the internal teeth, a pump unit including a rotor housing that houses both rotors, and a drive shaft that rotationally drives the pump unit The drive shaft has one end portion that is a free end and the other end portion that is coaxially supported with the outer rotor so as to be integrally rotatable, and between the outer rotor and the rotor housing. In addition, one rolling bearing for rotatably supporting the outer rotor with respect to the rotor housing is interposed.

  According to the electric gear pump configured as described above, the drive shaft is supported by the outer rotor whose one end is a free end and the other end is supported by the rolling bearing. No rolling bearing is required to support the side. For this reason, compared with the said prior art example, the number of bearings required in order to support a drive shaft and both rotors can be reduced, and the structure can be simplified. In addition, since one end portion of the drive shaft is a free end and there is no need to press-fit the bearing, the assembly of the electric gear pump is facilitated, and the manufacturing process can be simplified.

In the electric gear pump, the rolling bearing is formed with a rotation-side raceway surface formed on an outer peripheral surface of the outer rotor, and a fixed-side raceway surface facing the rotation-side raceway surface on an inner peripheral surface. It is preferable that a fixed ring fixed on the inner side and a plurality of rolling elements arranged so as to be freely rollable between the both raceway surfaces are provided.
In this case, since the outer rotor is also configured to serve as a rotating wheel of the rolling bearing, the structure can be simplified.

  According to the electric gear pump of the present invention, the structure and the manufacturing process can be simplified and the manufacturing cost can be reduced.

Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a configuration of an electric gear pump according to a first embodiment of the present invention. The electric gear pump 10 is used as a pump for pumping hydraulic oil in a transmission such as an automobile that requires only a relatively low discharge pressure. The electric gear pump 10 is disposed inside a metal housing 11 formed in a substantially cylindrical shape. The motor unit 20 and the pump unit 30 are provided.
The housing 11 is provided with a wall portion 12 for partitioning the inner space in the axial direction. The motor portion 20 is accommodated on one side, and an outer rotor 31 and an inner rotor, which will be described later, which are constituent members of the pump portion 30 on the other side. 33 etc. are accommodated. Further, the wall portion 12 is formed with a boss portion 13 having a hole portion 13a that communicates between the motor portion 20 side and the pump portion 30 side at the axial center thereof.

  The motor unit 20 includes a stator 21 fixed to the inner peripheral surface of the housing 11 and a rotor 22 facing the inner peripheral side of the stator 21 with a slight gap. The stator 21 is formed by winding a copper wire around a core made of laminated electromagnetic steel plates, and is disposed between the stator 21 and a lid 14 that closes an opening on one end side of the housing 11. Power is supplied from the control unit 23.

The rotor 22 is opposed to the stator 21 and has a magnet 24 in which N poles and S poles are alternately arranged in the circumferential direction alternately in the circumferential direction, and a cylindrical shape to which the magnet 24 is fixed. The spacer 25 has a drive shaft 26 press-fitted into the center hole 25a of the spacer 25. The drive shaft 26 has a free end on one end portion 26a side, and is inserted into a hole 13a formed in the wall portion 12 of the housing 11 on the other end side. Thirty outer rotors 31 are coaxially formed. An appropriate clearance is secured between the outer peripheral surface of the drive shaft 26 and the inner peripheral surface of the hole 13a to such an extent that the drive shaft 26 can rotate with respect to the boss portion 13.
Further, the boss portion 13 is provided with a seal member 15 that seals between the pump portion 30 and the drive shaft 26, and prevents hydraulic oil from entering the motor portion 20 from the pump portion 30. .

The pump unit 30 includes an outer rotor 31 formed on the drive shaft 26, a single ball bearing 32 disposed outside the outer rotor 31 and rotatably supporting the outer rotor 31 with respect to the housing 11, And a lid member 34 that closes an opening on the other end side of the housing 11 as a rotor housing that accommodates them.
As described above, the outer rotor 31 is formed in a disk shape coaxial with the drive shaft 26 at the other end of the drive shaft 26. Therefore, the outer rotor 31 is also coaxially integrated with the rotor 22 that includes the drive shaft 26.
The outer rotor 31 is held by the outer surface 12a of the wall portion 12 and the lid member 34 so as not to move in the axial direction. On the axial end surface of the outer rotor 31, there is formed a recess 31a that is recessed in the axial direction and in which an inner rotor 33, which will be described later, is disposed. The opening of the recess 31a is closed by the lid member 34 in a state where the inner rotor 33 is accommodated therein.

2 is a cross-sectional view taken along line II-II in FIG. Referring to FIGS. 1 and 2, the pump unit 30 constitutes a trochoid pump which is a kind of internal gear type gear pump, and an inner tooth 31b projecting inward on the inner peripheral surface of the recess 31a. Is formed.
The inner rotor 33 disposed inside the recess 31a is held so that the inner rotor 33 does not move in the axial direction by the bottom 31a1 of the recess 31a located on both side surfaces of the recess 31a and the lid member 34. Outer teeth 33a that mesh with the inner teeth 31b are formed on the surface. In addition, the inner rotor 33 is formed with a hole portion 33c that coincides with the center of the rotation axis and is press-fitted and fixed to the shaft member 35 that protrudes from the side surface 33b of the inner rotor 33. The protruding portion 35 a protruding from the inner rotor 33 of the shaft member 34 is rotatably inserted into a hole portion 34 a formed in the lid member 34. In addition, a predetermined clearance is provided between the inner rotor 33 and the bottom 31a1 of the recess 31a located on both side surfaces and the lid member 34. The inner rotor 33 rotates about the axis A of the hole 34a. And is rotatable with respect to the housing 11.

A raceway surface 31 c is formed on the outer peripheral surface of the outer rotor 31 as a rotation-side raceway surface of the ball bearing 32 that supports the outer rotor 31. The ball bearing 32 includes an outer ring 36 as a fixed ring that is fitted and fixed to the inner peripheral end portion 11 a of the housing 11, and a plurality of balls 37 that are interposed between the outer ring 36 and the outer rotor 31. . In the outer ring 36, a raceway surface 36 a as a fixed raceway surface on which a plurality of balls 37 roll is formed on the inner peripheral surface thereof so as to face the raceway surface 31 c on the outer peripheral surface of the outer rotor 31. The plurality of balls 37 are disposed between the raceway surfaces 31c and 36a so as to be freely rollable.
That is, the outer rotor 31 is configured to serve as a rotating wheel of the ball bearing 32 by forming the raceway surface 31c on the outer peripheral surface. The ball bearing 32 may be configured by fitting an inner ring having a raceway surface to the outer peripheral surface of the outer rotor 31, but the outer rotor 31 also serves as a rotating wheel of the ball bearing 32 as in the present embodiment. Thus, the structure can be simplified.

The ball bearing 32 configured as described above is interposed between the outer rotor 31 and the housing 11, and supports the outer rotor 31 so as to be rotatable with respect to the housing 11. Further, the ball bearing 32 also supports the drive shaft 26 (rotor 22) formed coaxially with the outer rotor 31 so as to be rotatable with respect to the housing 11. That is, the other end of the drive shaft 26 is supported on the outer rotor 31 so as to be coaxially and integrally rotatable. The motor unit 20 rotates the drive shaft 26 about the axis B that is the rotation center of the ball bearing 32. The outer rotor 31 is driven.
The axis B that is the rotation center of the outer rotor 31 and the rotor 22 is positioned below the axis A that is the rotation center of the inner rotor 33.

  In the electric gear pump 10 configured as described above, an external power source (not shown) is connected to the connector 27 attached to the outside of the housing 11, and power is supplied to the stator 21 via the connector 27 and the control unit 23 connected to the connector 27. Is done. When electric power is supplied to the stator 21, the rotor 22 rotatably supported by the ball bearing 32 rotates about the axis B. When the rotor 22 rotates, the outer rotor 31 also rotates together, and the inner rotor 33 having the outer teeth 33a that mesh with the inner teeth 31b of the outer rotor 31 is driven to rotate about the axis A. That is, the inner rotor 33 is driven and rotated in an eccentric state with respect to the axis B that is the rotation center of the outer rotor 31. At this time, a pumping action is generated by the volume change of the space formed by the external teeth 33a and the internal teeth 31b. The lid member 34 is provided with a suction port (not shown) and a discharge port (not shown) through which the internal space formed by the recess 31a communicates with the outside to suck hydraulic oil, and the outer rotor 31 and the inner rotor. The electric gear pump 10 can pump hydraulic fluid by the pump action 33.

  According to the electric gear pump 10 of the present embodiment configured as described above, the drive shaft 26 is supported by the outer rotor 31 supported by the ball bearing 32 at the other end while the one end 26a side is a free end. Therefore, a bearing for supporting the one end portion 26a side of the drive shaft 26 is not required. For this reason, compared with the said prior art example, the number of bearings required in order to support the drive shaft 26 and both the rotors 31 and 33 can be reduced, and the structure can be simplified. Further, since the one end portion 26a side of the drive shaft 26 is a free end and there is no need to press-fit the bearing, the assembly of the electric gear pump 10 is facilitated, and the manufacturing process can be simplified. As a result, the manufacturing cost can be reduced.

The electric gear pump of the present invention is not limited to the above embodiment. For example, in the above embodiment, a case where a trochoid pump, which is a kind of internal gear pump, is applied to the pump unit 30, but other internal gear pumps such as involute, paracoid, hypocycloid, etc. It can also be applied.
Moreover, in the said embodiment, although the outer rotor 31 and the drive shaft 24 were supported by the ball bearing 32, it can also be supported by other rolling bearings, such as a roller bearing.

It is sectional drawing which shows the structure of the electric gear pump which is 1st embodiment of this invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG.

Explanation of symbols

10 Electric Gear Pump 11 Housing (Rotor Housing)
DESCRIPTION OF SYMBOLS 20 Motor part 26 Drive shaft 26a One end part 30 Pump part 31 Outer rotor 31b Inner tooth | gear 31c Raceway surface 32 Ball bearing (rolling bearing)
33 Inner rotor 33a External teeth

Claims (2)

An outer rotor having internal teeth, an inner rotor having external teeth meshing with the internal teeth, and a pump unit including a rotor housing that accommodates both the rotors;
In an electric gear pump comprising a motor unit having a drive shaft that rotationally drives the pump unit,
The drive shaft is supported such that one end is a free end and the other end is coaxially and integrally rotatable with the outer rotor,
An electric gear pump characterized in that a single rolling bearing is interposed between the outer rotor and the rotor housing to rotatably support the outer rotor with respect to the rotor housing.   The rolling bearing has a rotation side raceway surface formed on the outer peripheral surface of the outer rotor, and a fixed side raceway surface facing the rotation side raceway surface on the inner peripheral surface and is fixed to the inner side of the rotor housing. The electric gear pump according to claim 1, further comprising a fixed ring and a plurality of rolling elements that are arranged to freely roll between the both raceway surfaces.

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