JP2004278444A - Electric inscribed gear pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small electric inscribed gear pump applicable to high-speed rotation and having excellent machine efficiency. <P>SOLUTION: This built-in motor type electric inscribed gear pump 1 comprises a rotor section 4 having an outer rotor 41 and an inner rotor 42, an electric motor section 3 for rotationally driving the inner rotor 42, a main shaft 5 integrally composed of a drive shaft of the electric motor 3 and a rotation shaft of the inner rotor, and a housing 2 storing them. The main shaft 5 is rotatably supported by a pair of rolling bearings 6 and 7. The pair of the rolling bearings 6 and 7, of which inner rings 6b and 7b are fixed to the housing 2 and outer rings 6a and 7a are fixed to the main shaft 5, are respectively stored in the axial inner side of both end surfaces of the main shaft 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electric internal gear pump.
[0002]
[Prior art]
A general electric pump is obtained by connecting an electric motor having a driving shaft and a pump having a rotating shaft by a joint. In such a motor / pump coupled type electric pump, a space for coupling the motor drive shaft and the pump rotary shaft is required, which is an obstacle to miniaturization. Generally, both ends in the axial direction of the motor drive shaft are supported by bearings inside the motor, and both ends in the axial direction of the pump rotary shaft are also supported by bearings. In other words, in the case of the electric pump of the motor / pump combination type, the motor and the pump individually have bearings. Therefore, a large number of bearings are used as the whole electric pump, which leads to an increase in cost and a space for arranging the bearings, which makes it more difficult to reduce the size.
[0003]
Therefore, it is conceivable to use the electric motor drive shaft and the pump rotation shaft in common to eliminate the need for the coupling part. Such a pump is disclosed, for example, in Patent Document 1. The motor described in Patent Document 1 includes a main shaft shared as a driving shaft of a motor and a rotating shaft of a pump. The main shaft is rotatably supported at two positions on both sides of a slide bearing provided on the pump side and a slide bearing provided on the motor side, so that the number of bearings is reduced. In addition, by adopting a plain bearing for the bearing, it is possible to save space compared to the case of using a rolling bearing, and furthermore, by adopting a motor that can be used in hydraulic oil, the pump and motor The shaft seal provided between them is omitted. As described above, the size of the electric inscribed gear pump is reduced by reducing the number of bearings, saving space by using slide bearings, and omitting the shaft seal.
[0004]
[Patent Document 1]
JP-A-2002-317772 (FIG. 1)
[0005]
[Problems to be solved by the invention]
However, the conventional electric internal gear pump has a problem that the rotational resistance of the main shaft becomes large because the frictional resistance of the slide bearing employed is very large. In addition, when a hydrodynamic bearing is used as a slide bearing, stable non-contact rotation can be achieved at high speed rotation, but the lubricating film is easily cut off at low speed rotation, and the contact rotation causes large rotation resistance, which may cause early burn-in. is there. As described above, the plain bearing has a problem that the mechanical efficiency is poor or it is difficult to cope with the fluctuation of the rotation speed.
[0006]
In view of the above, the present invention provides a motor-inscribed gear pump in which a main shaft sharing a drive shaft and a rotary shaft is supported by bearings on both axial sides of a motor unit, and reduces the axial length while employing rolling bearings as the bearings. It is an object of the present invention to provide an electric internal gear pump having excellent mechanical efficiency capable of coping with various rotations such as low-speed rotation, high-speed rotation, and frequent fluctuation of the number of rotations.
[0007]
[Means for Solving the Problems]
The present invention relates to a rotor section having an outer rotor having internal teeth and an inner rotor having external teeth meshing with the internal teeth, an electric motor section for driving the inner rotor to rotate, a drive shaft of the electric motor section, and the inner rotor. In a motor-integrated electric inscribed gear pump including a main shaft integrally formed with a rotary shaft, and a housing enclosing the rotor unit, the electric motor unit, and the main shaft, the main shaft includes a pair of rolling members. The pair of rolling bearings are rotatably supported by bearings, and the inner ring is fixed to the housing, the outer ring is fixed to the main shaft, and the pair of rolling bearings are respectively housed in the axial direction inside of both end surfaces of the main shaft. It is characterized by.
According to the present invention, since a pair of rolling bearings are housed inside both end faces of the main shaft, the axial length of the pump can be reduced despite the use of the rolling bearings. Further, by employing the rolling bearing, it is possible to cope with various rotations such as low-speed rotation, high-speed rotation, and frequent fluctuations in the number of rotations.
[0008]
Preferably, the housing is divided into a bottomed cylindrical housing main body having one end opened, and a lid closing an open side of the housing main body.
In this case, since the housing is composed of two members, the structure can be simplified.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The electric internal gear pump 1 according to the embodiment shown in FIG. 1 is configured as a trochoid pump, which is a kind of an internal gear pump, and has low pulsation and low noise. Used as a hydraulic pump for
[0010]
The pump 1 houses a motor unit 3 and a rotor unit 4 inside a housing 2, and is a drive shaft that is rotationally driven by the motor unit 3 and a main shaft 5 that also serves as a rotation axis of the rotor unit 4. Are provided rotatably.
The housing 2 is configured such that a housing body 21 and a lid 22 that are divided into two in the axial direction of the main shaft 5 are connected.
The housing main body 21 is made of, for example, a steel plate, is provided with a closed surface 23 on one side in the axial direction of the main shaft 5, and is formed in a bottomed cylindrical shape whose other side in the axial direction is open. A first convex portion 24 protruding inward in the axial direction is formed at the center of the closed surface 23 of the housing body 21.
[0011]
The lid 22 is made of, for example, a steel plate and is formed in a disk shape so as to cover the open side of the housing body 21, and a suction port (not shown) through which hydraulic oil is sucked and a discharge port through which hydraulic oil is discharged 8 is provided. The lid 22 is hermetically joined to the housing body 21 by a seal portion 25 and is separably connected and fixed by bolts 26. A second convex portion 27 protruding inward in the axial direction is formed at a radially central portion of the lid 22.
The housing 2 is divided into two parts, which are the minimum required in the assembly and maintenance management, thereby reducing the number of constituent parts. Further, since the number of parts such as seals and bolts necessary for the hermetic joining is reduced, the working time at the time of assembly is also reduced. As described above, the cost of the housing 2 is reduced by simplifying its configuration.
[0012]
The motor section 3 includes a stator 31 provided inside the housing main body 21 and a rotor 32 arranged inside the stator 31. The main shaft 5 serving as a drive shaft is internally fitted to the rotor 32 so as to rotate integrally therewith, and the main shaft 5 extends from the rotor 32 toward the rotor 4 in the axial direction. One axial end of the main shaft 5 is rotatably supported by a first rolling bearing 6, and the other axial end of the main shaft 5 is rotatably supported by a second rolling bearing 7. I have.
[0013]
The motor unit 3 is formed of an in-oil motor that can operate even in hydraulic oil, and a shaft seal normally provided between the motor unit 3 and the rotor unit 4 is omitted. Accordingly, the space for providing the shaft seal is not required, and the axial length of the pump 1 is accordingly reduced.
Further, by omitting the shaft seal, hydraulic oil flows into the motor unit 3 side, and the flowing hydraulic oil contributes to cooling of the motor unit 3 that generates heat by rotation. That is, the cooling effect of the motor unit 3 can be obtained by the working oil without depending only on the air cooling by the heat radiation from the housing 2. Therefore, the size of the housing 2 is smaller than that of the housing 2 relying only on air cooling.
[0014]
The main shaft 5 includes a hollow cylindrical shaft portion 51 and a rotor extension portion 52 formed at one end of the shaft portion 51 and extending radially outward.
A first peripheral groove 53 into which the bearings 6 and 7 are incorporated and a second peripheral groove 54 are formed on the inner peripheral side at both axial ends of the shaft portion 51.
The first rolling bearing 6 is incorporated in the first circumferential groove 53 of the shaft portion 51 on the side where the rotor extension portion 52 is not formed, and the side where the extension portion 52 is formed. The second rolling bearing 7 is incorporated in the second circumferential groove 54.
[0015]
Each of the rolling bearings 6, 7 incorporated in each of the circumferential grooves 53, 54 is a ball bearing having outer rings 6a, 7a, inner rings 6b, 7b, balls 6c, 7c, and a retainer (not shown). .
The outer rings 6a, 7a of the rolling bearings 6, 7 are fitted and fixed to the peripheral surfaces 53a, 54a of the peripheral grooves 53, 54 formed in the shaft portion 51, respectively. The inner race 6b of the first rolling bearing 6 is fitted and fixed to the first projection 23 of the housing body 21, and the inner race 7b of the second rolling bearing 7 is fitted to the second projection 27 of the lid 22. ing.
[0016]
The axial width of each of the circumferential grooves 53 and 54 is formed to be larger than the axial width of each of the rolling bearings 6 and 7. It is housed without protruding outside.
As described above, since the first rolling bearing 6 and the second rolling bearing 7 are accommodated without protruding inside the both end surfaces of the shaft portion 51, the rolling bearings 6 and 7 are used for the bearing. Nevertheless, the axial length of the pump 1 is short and the pump 1 is downsized.
[0017]
In addition, the pump 1 employs the rolling bearings 6 and 7 having low frictional resistance and excellent mechanical efficiency and excellent rotational stability when the rotational speed fluctuates, so that the pump 1 can cope with various rotations. Therefore, the present invention is suitable for a pump that operates with a large amount of ON-OFF and rotational speed fluctuations, such as a transmission drive hydraulic pump for an automobile. In addition, since it is more suitable for high-speed rotation than a plain bearing, the flow rate can be secured even if the pump is downsized. Further, since the rolling bearings 6 and 7 are lubricated by the operating oil flowing from the rotor 4, the lubricating performance is sufficiently secured without using a grease-sealed bearing with a seal or providing another lubrication mechanism. Since it has a simple configuration, troubles caused by damage to the bearing portion can be suppressed, and the cost is low.
[0018]
The rotor unit 4 is a trochoid pump as described above, and includes the outer rotor 41 having the internal teeth 41a and the inner rotor 42 having the external teeth 42a meshing with the internal teeth 41a.
The inner rotor 42 of the rotor unit 4 is externally fitted to the outer peripheral surface 52 a of the rotor extension portion 52 of the main shaft 5 so as to be integrally rotatable. For this reason, when the main shaft 5 is driven to rotate by the motor unit 3, the inner rotor 42 also rotates. When the inner rotor 42 rotates, the outer rotor 41 meshing with the inner rotor 42 also rotates eccentrically, and a pumping action occurs between the outer rotor 41 and the inner rotor 42. Hydraulic oil is sucked between the outer and inner rotors 41 and 42 from a suction port provided in the lid 22, and is discharged from a discharge port 8 provided in the housing 22.
[0019]
【The invention's effect】
According to the present invention, the first rolling bearing and the second rolling bearing are respectively housed inside the both end surfaces of the main shaft, so that the axial length of the pump is reduced despite the use of the rolling bearing. It is short and can be miniaturized. In addition, by employing the rolling bearing, it is possible to improve mechanical efficiency and to cope with various rotations such as low-speed rotation, high-speed rotation, and frequent fluctuations in the number of rotations.
[Brief description of the drawings]
FIG. 1 is a sectional view of an electric internal gear pump according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electric inscribed gear pump 2 Housing 21 Housing main body 22 Cover 3 Motor part 4 Rotor part 41 Outer rotor 41a Inner teeth 42 Inner rotor 42a Outer teeth 5 Main shaft 51a Inner peripheral surface 6 First rolling bearing 6a Outer ring 6b Inner ring 7 Second rolling bearing 7a Outer ring 7b Inner ring

Claims (2)

A rotor portion including an outer rotor having internal teeth and an inner rotor having external teeth meshing with the internal teeth,
An electric motor section that rotationally drives the inner rotor,
A main shaft in which a drive shaft of the electric motor unit and a rotation shaft of the inner rotor are integrally formed,
A motor-integrated electric inscribed gear pump comprising a housing enclosing the rotor section, the electric motor section, and the main shaft,
The main shaft is rotatably supported by a pair of rolling bearings,
The pair of rolling bearings, wherein an inner ring is fixed to the housing, an outer ring is fixed to the main shaft, and each of the pair of rolling bearings is housed in an axially inner side of both end surfaces of the main shaft. . 2. The electric internal gear pump according to claim 1, wherein the housing is divided into a bottomed cylindrical housing main body having one end opened and a lid closing an open side of the housing main body. 3.

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