JP2004204694A - Electric inscribed gear pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent inferior rotation in a pump section in a simple constitution when a main spindle served as a drive shaft and a rotary shaft is supported by bearings in axial both sides of a motor section. <P>SOLUTION: This motor integrated type electric inscribed gear pump is provided with a rotor part 3 which has an outer rotor 25 having an internal tooth 25a and an inner rotor 26 having an external tooth 26a geared with the internal tooth 25a, the electric motor part 4 rotatingly driving the inner rotor 26, and the main spindle 5 coaxially and integrally comprising the drive shaft of the electric motor part 4 and the rotary shaft of the inner rotor 26. The main spindle 5 is supported only by the first bearing 10 and the second bearing 16 in the axial both sides and the rotor part 3 is disposed between the both bearings 10 and 16. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric internal gear pump, particularly an electric internal gear pump suitable as a pump for transmission of an automobile.
[0002]
[Prior art]
A general electric pump is configured by connecting an electric motor having a drive shaft and a pump having a rotary shaft by a joint. In such a motor / pump coupled type electric pump, a coupling portion between the motor drive shaft and the pump rotation shaft is required, so that a space for the coupling portion is required, which hinders miniaturization, and which is different from the coupling portion. There is a problem such as generation of sound. In addition, the motor drive shaft is generally supported by bearings at both axial ends inside the motor. However, in the case of an electric pump combined with a motor / pump, a bearing for supporting the rotary shaft is also provided on the pump. Needed. Therefore, many bearings are used for the electric pump as a whole, which leads to an increase in cost and a space for disposing the bearings.
[0003]
Therefore, it is conceivable that the electric motor drive shaft and the pump rotation shaft are made common to eliminate the need for the coupling portion. 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 bearing A provided on the pump side and a bearing B provided on the motor side, so that the number of bearings can be reduced.
[0004]
[Patent Document 1]
JP-A-9-32738 (Claims, FIG. 1)
[0005]
[Problems to be solved by the invention]
However, in the device described in Patent Document 1, the pump is provided axially outside the bearing A on the pump side. That is, the pump is located outside the range in which the main shaft is supported by the bearings A and B. The main shaft outside the range supported by the dual bearings A and B is in a so-called cantilever state and may be bent, and if the pump is provided in such a range, it causes poor rotation. .
[0006]
Further, in order to prevent poor rotation, it is conceivable to add a bearing so that the pump portion is also supported at both ends. However, the addition of the bearing is not preferable because it increases the number of parts and increases the size.
In view of the above, the present invention has a simple configuration and prevents poor rotation at a pump portion when a main shaft in which a drive shaft and a rotary shaft are shared is supported by bearings on both axial sides of a motor unit. The purpose is to:
[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 rotating and driving the inner rotor, a drive shaft of the electric motor section, and the inner rotor. A motor-integrated electric inscribed gear pump comprising:
Here, the internal gear pump is meant to include all internal gear pumps such as trochoid, involute, parachoid, and hypocycloid.
[0008]
The main shaft is supported only by the first and second bearings on both sides in the axial direction, and a simple configuration with a small number of bearings is ensured. Further, in the present invention, since the rotor portion is disposed between the two bearings where bending does not occur in the main shaft, it is possible to prevent a rotation failure from occurring in the rotor portion which is a portion of the pump.
[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 a hydraulic pump for an automobile transmission that requires only a relatively low pressure of about 0.4 MPa to 1 MPa. The pump 1 is configured as a trochoid pump, which is a kind of an internal gear pump. Although the efficiency is slightly inferior, the pump 1 has little pulsation and low noise, and is suitable as a transmission pump.
[0010]
The pump 1 is configured by housing an electric motor unit 3 and a rotor unit 4 inside a pump housing 2, and inside the housing 2 is a drive shaft that is rotationally driven by the motor unit 3 and a rotor unit 4. The main shaft 5, which also serves as a rotation shaft, is rotatably provided. Both ends in the axial direction of the main shaft 5 are rotatably supported by bearings 10 and 16 provided in the housing 2.
[0011]
The housing 2 is made of a steel plate, and is configured by connecting a motor housing 7 mainly storing the motor unit 3 and a rotor housing 8 mainly storing the rotor unit 4. The motor housing 7 is formed in a cylindrical shape in which a surface 9 on one side in the axial direction (the opposite side to the rotor portion 4) is closed and a surface on the other side in the axial direction is open. The part is provided with a rolling bearing (first bearing) 10 for rotatably supporting one axial end of the main shaft 5. The first bearing 10 has an outer ring 10a attached to the rotor housing 8 side and an inner ring 10b attached to the main shaft 5 side.
[0012]
The rotor housing 8 is configured by connecting a first divided body 11 and a second divided body 12 divided in the axial direction of the main shaft 5. The first divided body 11 attached to the opening surface on the other axial side of the motor housing 7 is hermetically joined to the motor housing 7 by a seal portion 14 and is separably connected and fixed by bolts 15. On the joint surface 11a of the first divided body 11 with the second divided body 12, a concave portion 17 serving as a rotor chamber for accommodating the rotor portion 4 is formed in the thickness direction of the first divided body 11 (axial direction of the main shaft 5). It is formed concave. The concave portion 17 has a peripheral surface 17a eccentric with respect to the axis of the main shaft 5, and further has a thickness of the first divided body 11 toward the motor housing 7 at the center of the concave bottom surface 17b. A through hole 18 is formed to penetrate in the vertical direction (axial direction of the main shaft 5), and the main shaft 5 is inserted into the through hole 18. Further, the first divided body 11 includes a seal member 18 a for sealing the rotor chamber 17 inside the motor housing 7 around the main shaft 5.
[0013]
The second divided body 12 is attached to the joint surface 11a of the first divided body 11 in an overlapping manner, and the joint surface between the first divided body 11 and the second divided body 12 is sealed by a seal portion 19. . The first divided body 11 and the second divided body 12 are separably connected and fixed by bolts 20.
The second divided body 12 includes a rolling bearing (second bearing) 16 for rotatably supporting the other end of the main shaft 5 in the axial direction. In order to provide the second bearing 16, a concave portion 21 which is recessed in the thickness direction of the second divided body 12 is formed on a joint surface 12 a of the second divided body 12 with the first divided body 11. The outer ring 16a of the rolling bearing 16 is attached to the inner peripheral surface of the concave portion 21, and the inner ring 16b is attached to the main shaft 5 side.
[0014]
The motor section 3 includes a stator 22 mounted inside the motor housing 7, and a rotor 23 is arranged inside the stator. The main shaft 5 serving as a drive shaft is internally fitted to the rotor 23 so as to rotate integrally therewith, and the main shaft 5 extends from the rotor 23 to both sides in the axial direction. One end in the axial direction of the main shaft 5 is rotatably supported by the first bearing 10. The other axial end of the main shaft 5 extends through the through hole 18 and the rotor chamber 17 of the first divided body, extends to the recess 21 of the second divided body 12, and is rotatably supported by the second bearing 16. ing.
[0015]
The rotor section 4 is disposed in a rotor chamber 17 between the second bearing 16 and the motor section 3. The rotor section 4 is a trochoid pump as described above, and has an outer rotor 25 having internal teeth 25a. And an inner rotor 26 having external teeth 26a meshed with the internal teeth 25. The inner rotor 26 is fitted around the main shaft 5. When the main shaft 5 is driven to rotate by the motor unit 3, the inner rotor 26 also rotates. When the inner rotor 26 rotates, the outer rotor 25 meshing with the inner rotor 26 also rotates eccentrically, and a pumping action occurs between the outer rotor 25 and the inner rotor 26. Oil is sucked into the space between the outer and inner rotors 25 and 26 from a suction port (not shown), and is discharged from a discharge port (not shown).
[0016]
In the present embodiment, the main shaft 5, which is the drive shaft of the motor unit 3, is supported at both ends in the axial direction by the first bearing 10 and the second bearing 16 in a doubly supported manner. Since the rotor section 4 is disposed and the main shaft 5 also serves as the rotation axis of the rotor section 4, the rotor section 4 can rotate in a state where bending of the main shaft 5 is unlikely to occur, and poor rotation is prevented. I have.
[0017]
FIG. 2 shows an electric inscribed pump 1 as a comparative example. The main difference from the electric inscribed pump 1 according to the embodiment is that the second bearing 16 is provided between the motor unit 3 and the rotor unit 4. It is a point which is arranged in. In the case of the arrangement of the bearings in the comparative example, when the main shaft 5 is viewed from the rotor portion 4, the main shaft 5 is supported only in a cantilever state by the second bearing 16, and the main shaft 5 is bent to cause rotation failure. It may be.
On the other hand, in the present embodiment, the rotor portion 4 is located at an intermediate position of the main shaft 5 in the double-supported state supported by the dual bearings 10 and 16, so that the main shaft 5 is supported by both the motor portion 3 and the rotor portion 4. In this state, the occurrence of rotation failure is prevented.
Here, in the comparative example of FIG. 2, the points that are not described are the same as those of the pump 1 according to the embodiment of FIG. 1, and are denoted by the same reference numerals.
[0018]
Note that the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the matters described in the claims.
[0019]
【The invention's effect】
According to the present invention, since the rotor portion is disposed between the first bearing and the second bearing, occurrence of rotation failure in the rotor portion is prevented.
[Brief description of the drawings]
FIG. 1 is a sectional view of an electric internal gear pump according to an embodiment.
FIG. 2 is a cross-sectional view of an electric internal gear pump according to a comparative example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electric inscribed gear pump 3 Motor part 4 Rotor part 5 Main shaft 10 Rolling bearing (first bearing)
16 Rolling bearing (second bearing)
25 outer rotor 25a inner teeth 26 inner rotor 26b outer teeth

Claims (1)

1. 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 drive shaft of the electric motor unit and a rotation shaft of the inner rotor, the main shaft is integrally formed coaxially,
   In the motor-integrated electric internal gear pump equipped with
   The main shaft is supported only by the first and second bearings on both axial sides,
   The electric internal gear pump, wherein the rotor unit is disposed between the two bearings.

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