JP4821401B2 - Electric gear pump - Google Patents

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. Such an electric gear pump includes an inner rotor having external teeth and an outer rotor having internal teeth meshing with the external teeth, and is configured to rotationally drive either the outer rotor or the inner rotor by a motor. .
In such an electric gear pump, usually, a pump part composed of both rotors and a motor part for driving them are arranged in parallel in the axial direction, and the axial dimension may be relatively large.
On the other hand, by incorporating an outer rotor into the rotor, the outer rotor is driven, and a gear pump is configured on the inner side of the motor to reduce its axial size (see, for example, Patent Document 1). .

Japanese Patent Laying-Open No. 2003-129966 (FIG. 1)

The rotor of the conventional example is rotatably supported by forming a sliding bearing with a resin film formed on the inner peripheral surface of the stator and the outer peripheral surface of the rotor. Since a slight clearance is usually provided between the rotating side and the stationary side of the slide bearing, in the electric gear pump of the above conventional example, a slight shaft runout occurs on the rotating shaft of the rotor, and the rotor and the fixed side are fixed. There was a risk that the children would stick together. When the rotor and the stator are adsorbed, a stable rotational driving force cannot be obtained, and a stable pump performance cannot be obtained.
In addition, the sliding bearing used in the above-described conventional example may have excessive friction when starting rotation from the stopped state because the peripheral surfaces of the fixed side and the rotating side are in contact with each other in the stopped state. is there. Furthermore, even when rotating, if the rotational speed does not increase moderately, a sufficient oil film will not be formed between the fixed side and the rotating side. As a result of the shaft runout of the rotor, abnormal wear or the like occurs on the peripheral surfaces of each other, and the life of the electric gear pump may be significantly reduced.
The present invention has been made in view of such circumstances, and provides an electric gear pump capable of obtaining stable pump performance and maintaining high durability even if the rotor is made compact by providing an outer rotor. The purpose is to do.

The electric gear pump according to the present invention includes a stator of the motor, an inner rotor of the motor that is disposed on the inner side of the stator, and an outer tooth that meshes with the inner teeth. An inner rotor that is driven and rotated eccentrically with respect to the center of the rotor by rotation of the outer rotor, a pair of housings that are arranged on both sides of the rotor and the inner rotor, and hold these, and the pair of pairs at least one side of the housing of the housing, is disposed between the rotor, have a, a rolling bearing for supporting the rotor, the inner rotor, the rotary shaft and the shaft center matches A through hole is formed, protrudes from both side surfaces of the inner rotor and is inserted into the through hole, and both ends thereof are fixed to the pair of housings. Further comprising a shaft member for rotatably supporting the inner rotor,
The shaft member has a pair of small diameter portions formed at both ends thereof and press-fitted and fixed to the pair of housings, and a large diameter portion formed larger in diameter than the small diameter portion and supporting the inner rotor, Between the small-diameter portion and the large-diameter portion, a pair of side wall portions that are in contact with the pair of housings and define the interval between the pair of housings are formed on both sides of the large-diameter portion. the peripheral surface, said tubular bushing constituting a sliding bearing together with the outer peripheral surface of the large diameter portion is characterized that you have been pressed.

According to the electric gear pump configured as described above, since the rotor including the outer rotor is supported by the rolling bearing, it is possible to suppress the shaft shake that occurs on the rotating shaft of the rotor. Therefore, the rotor and the stator can be prevented from adsorbing to each other by magnetic force, and a stable rotational driving force can be obtained. As a result, stable pump performance can be ensured.
Further, according to the above electric gear pump, since the rotor is supported not by the sliding bearing as in the conventional example but by the rolling bearing, the rotation of the rotor can be performed even if the operation and the stop are frequently repeated. It is possible to prevent wear on the part and maintain high durability.

Further, the electric gear pump, the inner rotor has a through hole that matches the rotation center is formed, while being inserted into the through hole to protrude from both sides of the inner rotor, both end portions of the pair housing are fixed by further has a shaft member for rotatably supporting the inner rotor, for example, rotatably supporting a shaft member with the inner rotor to the shaft member relative to the pair of housings and the inner rotor and integrally rotatable in Compared to the case, since only the inner rotor is rotatably supported with respect to the shaft member fixed to the pair of housings, the structure can be simplified and the manufacturing cost can be reduced.

Further, the electric gear pump, the shaft member, the pair of side wall portions defining an interval between the pair of housings in contact respectively with the pair of housings are formed by a pair of side wall portions, a pair of housings By defining the distance between the inner rotor and the outer rotor between the pair of housings, the clearance between the housing and the housing can be set to an appropriate dimension and maintained. As a result, frictional wear between the housing and both rotors can be suppressed, and liquid supplied and discharged by the electric gear pump can be prevented from leaking from the inside of the pump.

  According to the electric gear pump of the present invention, even if the rotor is made compact by providing the outer rotor, stable pump performance can be obtained and high durability can be maintained.

Next, reference examples will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a configuration of an electric gear pump as a reference example . The electric gear pump 1 is used as a pump for pumping hydraulic oil in a transmission of an automobile or the like that requires only a relatively low discharge pressure, and constitutes a trochoid pump that is a kind of internal gear pump.

The electric gear pump 1 includes a stator 3 and a rotor 4 constituting a motor M housed in a cylindrical case 2, and an internal gear pump together with an inner rotor 10 described later is provided on the rotor 4. The outer rotor 5 to be configured is incorporated, and an internal gear pump is configured on the inner side of the motor M.
The stator 3 is formed by winding a copper wire around a core made of laminated electromagnetic steel plates, and is fixed to the inner peripheral surface 2 a of the case 2. The rotor 4 is arranged on the inner peripheral side of the stator 3 so as to face the stator 3 with a slight gap.
The rotor 4 includes an outer rotor 5 formed in a substantially cylindrical shape, and a cylindrical magnet 6 that is fixed to the outer peripheral surface of the outer rotor 5 and faces the stator 3.

2 is a cross-sectional view taken along line II-II in FIG. 1 and 2, the outer rotor 5 includes a rotor portion 5a having an inner surface 5a1 formed with inner teeth 5a2 projecting in the inner circumferential direction, and both axial ends from the outer circumferential end of the rotor portion 5a. A pair of extending cylindrical portions 5b. A pair of ball bearings 7 is disposed between the inner peripheral surface of the cylindrical portion 5b and first and second housings 8 and 9, which will be described later, and the rotor 4 includes first and second rotors. The housings 8 and 9 are rotatably supported.
An inner rotor 10 having outer teeth 10a that mesh with the inner teeth 5a2 is disposed on the inner surface 5a1 side of the outer rotor 5. The inner rotor 10 is formed with a through hole 10b whose axis of rotation coincides with the center of the shaft. The shaft member 11 protruding from both side surfaces of the inner rotor 10 is press-fitted into the through hole 10b so as to be integrally rotatable. .

  On both sides of the rotor 4 and the inner rotor 10, first and second housings 8 and 9 are arranged so as to sandwich them, and hold the rotor 4 and the inner rotor 10. Both housings 8 and 9 are made of, for example, an aluminum alloy, and have substantially cylindrical holding portions 8a and 9a for holding the rotor 4 and the inner rotor 10, and axially outer edges of the holding portions 8a and 9a. And has flanges 8b and 9b extending radially outward. The case 2 is interposed inside the outer peripheral end portions of the both flange portions 8b and 9b, and both end portions of the case 2 and the outer peripheral end portions of the flange portions 8b and 9b are connected to each other. In this way, the space 2 in which the stator 3 and the rotor 4 are accommodated is configured by connecting the case 2 and the housings 8 and 9 together.

As described above, the pair of ball bearings 7 are fitted on the outer peripheral surfaces of the holding portions 8a and 9a of both the housings 8 and 9. The ball bearing 7 has an outer ring 7a fitted on the inner circumferential surface of the cylindrical portion 5b of the outer rotor 5 and an inner ring 7b fitted on the outer circumferential surfaces of the holding portions 8a and 9a. The holding parts 8a and 9a are supported with the axis A as the center of rotation. The pair of ball bearings 7 are disposed so as to be in contact with and sandwiched on both side surfaces of the rotor portion 5 a of the outer rotor 5, and the axial interval between the pair of ball bearings 7 is defined. Seal members 12 and 13 for closing the openings of the cylindrical portion 5b and the outer peripheral surfaces of the holding portions 8a and 9a are disposed on the outer side of the ball bearing 7, respectively.
In addition, holes 8a2 and 9a2 into which the shaft member 11 press-fitted into the inner rotor 10 is respectively inserted in the inner side surface 8a1 of the holding portion 8a and the inner side surface 9a1 of the holding portion 9a are positioned above the axis A. The axis B to be formed is the central axis. Bushings 14 and 15 that constitute a slide bearing by being interposed between the inner peripheral surfaces of the holes 8a2 and 9a2 and the outer peripheral surface of the shaft member 11, respectively, are press-fitted. , 9 are rotatably supported.

  A controller 16 for controlling electric power supplied to the stator 3 is disposed on the outer surface 8 c of the first housing 8, and a cover member 17 that covers the controller 16 is fixed.

In the electric gear pump 1 configured as described above, the electric power is supplied to the stator 3 by the controller 16 so that the rotor 4 that constitutes the motor M together with the stator 3 rotates about the axis A. When the rotor 4 rotates, the outer rotor 5 also rotates together. When the outer rotor 5 is rotated by the rotation of the rotor 4, the inner rotor 10 having the outer teeth 10 a meshing with the inner teeth 5 a 2 of the outer rotor 5 is driven to rotate about the axis B. That is, the inner rotor 10 is driven to rotate in an eccentric state with respect to the axis A that is the rotation center of the outer rotor 5. At this time, a pumping action is generated by the volume change of the space formed by the external teeth 10a and the internal teeth 5a2. Note that the holding portion 9a of the second housing 9 is connected to the suction port 18 through which the inner side surface 9a1 communicates with the outside and sucks the working oil, and the discharge port through which the inner side surface 9a1 communicates with the outside. An outlet 19 is provided.
In addition, by providing the outer rotor 5 in the rotor 4 as described above, the configuration in which the outer rotor 5 is driven is compared with the case where the internal gear pump and the motor that drives the motor are arranged in parallel. The axial dimension of the gear pump 1 can be reduced, and the electric gear pump 1 can be made more compact.

According to the electric gear pump 1 of the reference example configured as described above, the rotor 4 provided with the outer rotor 5 is supported by the ball bearing 7, so that the shaft shake generated on the rotating shaft of the rotor is suppressed. Can do. Therefore, the rotor 4 and the stator 3 can be prevented from adsorbing to each other by magnetic force, and a stable rotational driving force can be obtained. As a result, stable pump performance can be ensured. Further, since the rotor 4 is supported by the ball bearing 7 instead of being supported by the sliding bearing as in the above-described conventional example, even if the operation and the stop are repeated frequently, wear at the rotating portion of the rotor 4 is prevented. And maintain high durability.
As described above, according to the electric gear pump 1 of the reference example , even if the rotor 4 is provided with the outer rotor 5 to achieve compactness, stable pump performance can be obtained and high durability can be maintained. .

Figure 3 is a partial sectional view showing an electric gear pump 1 is the implementation of the invention. The main difference between this embodiment and the above-mentioned reference example is that the shaft member 11 is press-fitted and fixed to both the housings 8 and 9, and the inner rotor 10 is rotatable with respect to the shaft member 11. A pair of side wall portions that abut against the housing 9 and define the axial distance between the housings 8 and 9 are formed on the outer peripheral surface of the shaft member 11. The other points are the same as in the above reference example, and thus the description thereof is omitted. Further, in FIG. 3, the gap between the rotor portion 5 a and the inner rotor 10 and the housings 8 and 9 is exaggerated for easy understanding of the drawing.

  In FIG. 3, the shaft member 11 has a small diameter portion 11a formed at both ends thereof and press-fitted into the holes 8a2 and 9a2 of the housings 8 and 9, and has a larger diameter than the small diameter portion 11a and supports the inner rotor 10. And a large diameter portion 11b. Between the small-diameter portion 11a and the large-diameter portion 11b, a pair of side wall portions 11c parallel to the axially orthogonal plane and facing outward in the axial direction are formed on both sides of the large-diameter portion 11b.

A cylindrical bush 20 that constitutes a sliding bearing together with the outer peripheral surface of the large-diameter portion 11 b of the shaft member 11 is press-fitted into the inner peripheral surface of the through hole 10 b of the inner rotor 10, and the inner rotor 10 includes the shaft member 11. It can rotate freely.
That is, the shaft member 11 is inserted into the through hole 10b through the bush 20 with the small diameter portion 11a protruding from both side surfaces of the inner rotor 10, and the small diameter portion 11a is inserted into the hole portions 8a2 of the housings 8 and 9. The inner rotor 10 is rotatably supported by being press-fitted and fixed to 9a2.
On the other hand, for example, when the shaft member 11 can rotate integrally with the inner rotor 10, the shaft member 11 and the inner rotor 10 are supported together with the inner rotor 10 with respect to both the housings 8 and 9. Therefore, it is necessary to provide a sliding bearing such as a bush at each of the two ends.
On the other hand, in the present embodiment, only the inner rotor 10 is rotatably supported by the shaft member 11 that is press-fitted and fixed to both the housings 8 and 9. It suffices to provide a location, the structure can be simplified, and the manufacturing cost can be reduced.

  Further, the side wall portion 11 c of the shaft member 11 is in contact with the inner side surfaces 8 a 1 and 9 a 1 of the housings 8 and 9, and the shaft member 11 is sandwiched between the housings 8 and 9. In this way, the large-diameter surface 11b of the shaft member 11 is interposed between the housings 8 and 9 with the side wall portions 11c on both sides in contact with each other. It is prescribed to a predetermined dimension. The distance C between the housings 8 and 9 is set to be, for example, about 20 to 100 μm larger than the axial thickness dimension D of the rotor portion 5a and the inner rotor 10, and the distance between the rotor portion 5a and the inner rotor 10 is set. It is set so that a clearance of about 10 to 50 μm can be secured on both sides.

  In the present embodiment, the pair of side walls 11c formed on the shaft member 11 defines the distance between the housings 8 and 9 to a predetermined size as described above, so that the shafts 11 are disposed between the housings 8 and 9. The clearance between the inner rotor 10 and the rotor portion 5a and the housings 8 and 9 can be set and maintained at appropriate dimensions. As a result, frictional wear between the housings 8 and 9 and the inner rotor 10 and the rotor portion 5a can be suppressed, and hydraulic fluid supplied and discharged by the electric gear pump 1 can be prevented from leaking from the inside of the pump.

The electric gear pump of the present invention is not limited to the above embodiment. For example, in each of the above embodiments, a case where a trochoid pump is applied as the inscribed gear pump is illustrated, but other internal gear pumps such as involute, paracoid, hypocycloid, and the like can also be applied.
Moreover, in each said embodiment, although the rotor 4 was supported by the ball bearing 7, other rolling bearings, such as a roller bearing and a tapered roller bearing, can also be applied, for example. Furthermore, in each said embodiment, although the rotor 4 was supported by a pair of ball bearing 7, it is good also as a structure which supports one side by rolling bearings, such as a ball bearing 7, etc., and the other by a sliding bearing.

It is sectional drawing which shows the structure of the electric gear pump which is a reference example . FIG. 2 is a cross-sectional view taken along line II-II in FIG. Some showed an electric gear pump 1 is the implementation form of the present invention is a cross-sectional view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric gear pump 3 Stator 4 Rotor 5 Outer rotor 5a2 Internal tooth 7 Ball bearing (rolling bearing)
8 1st housing 9 2nd housing 10 Inner rotor 10a External tooth 10b Through hole 11 Shaft member 11c Side wall part M Motor

Claims (1)

The stator of the motor,
A rotor of the motor that is disposed inward of the stator and includes an outer rotor having internal teeth;
An inner rotor that has outer teeth that mesh with the inner teeth, and that is driven and rotated in an eccentric state with respect to the center of the rotor by rotation of the outer rotor;
A pair of housings arranged on both sides of the rotor and the inner rotor to hold them;
Wherein a pair of at least one side of the housing of the housing, is disposed between the rotor, have a, a rolling bearing for supporting the rotor,
The inner rotor is formed with a through hole whose axis of rotation coincides with the center of the shaft,
The shaft further includes a shaft member that protrudes from both side surfaces of the inner rotor and is inserted into the through hole, and whose both end portions are fixed to the pair of housings and rotatably supports the inner rotor,
The shaft member has a pair of small diameter portions formed at both ends thereof and press-fitted and fixed to the pair of housings, and a large diameter portion formed larger in diameter than the small diameter portion and supporting the inner rotor,
Between the small-diameter portion and the large-diameter portion, a pair of side wall portions that abut against the pair of housings and define the interval between the pair of housings are formed on both sides of the large-diameter portion,
Wherein the through hole inner peripheral surface of the inner rotor, the electric wherein tubular bushing constituting a sliding bearing together with the outer peripheral surface of the large diameter portion is characterized that you have been press-fitted gear pump.

Images