JP2006274927A - Internal gear pump and electric pump using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal gear pump with increased driving efficiency and operating efficiency and an electric pump using the internal gear pump. <P>SOLUTION: This internal gear pump comprises a rolling bearing part 37 having a rotating track surface 37a formed on the outer peripheral surface of an outer rotor 36, a fixed track surface 37b formed on the cylindrical inner peripheral surface 33d of a rotor housing body 33, and a plurality of needle-like rollers 37c rollingly disposed between the both tracks. The rotor housing body 33 supports the outer rotor 36 by the rolling bearing part 37. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an internal gear pump particularly suitable as a lubricating oil pump for automobile transmissions and an electric pump using the internal gear pump.

Conventionally, as a pump for pumping lubricating oil in a transmission such as an automobile, an electric pump that rotates an internal gear pump such as a trochoid pump with a motor is used. Among these, the internal gear pump is driven to rotate by a motor and has an inner rotor having outer teeth, an outer rotor having inner teeth meshing with the outer teeth, and the outer rotor inserted therein to rotate the outer rotor. And a rotor housing supporting the same. The outer rotor is configured to mesh with the outer teeth of the inner rotor, whose inner teeth are rotationally driven, and rotate on the inner peripheral surface of the rotor housing. 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.
When the outer rotor rotates at a constant speed, the plain bearing is in a fluid lubrication state by interposing lubricating oil pumped by the pump, and supports the outer rotor via an oil film.
On the other hand, when the electric pump is in a stopped state, that is, when the outer rotor is in a stopped state, the outer peripheral surface of the outer rotor and the inner peripheral surface of the rotor housing are in metal contact. Excessive frictional force is generated between the outer peripheral surface of the rotor and the inner peripheral surface of the rotor housing, which may increase the rotational torque or cause seizure between the two.
Therefore, an attempt has been made to improve the durability of the internal gear pump by forming an electroless nickel plating layer on the outer peripheral surface of the outer rotor and the inner peripheral surface of the rotor housing to improve seizure resistance ( For example, see Patent Document 1).

JP-A-8-144964 (page 3)

If an electroless nickel plating layer is formed on the outer peripheral surface of the outer rotor and the inner peripheral surface of the rotor housing as in the above conventional example, the durability of the pump is improved, but the outer rotor is still supported by the rotor housing by the sliding bearing. Therefore, the rotational torque accompanying the sliding friction is high, and the driving efficiency of the internal gear pump is reduced, and the operating efficiency of the entire electric pump is also reduced.
Further, when starting the electric pump from a stopped state, in order to rotate the pump, as described above, the motor itself must be operated together with a high rotational torque due to excessive frictional force caused by metal contact between the outer rotor and the rotor housing. Since a rotational torque for starting rotation is also required, a very high load acts on the motor. For this reason, a large inrush current instantaneously flows through the motor unit, which may adversely affect other electronic devices of the vehicle to which the electric pump is attached.
The present invention has been made in view of such circumstances, and an object thereof is to provide an internal gear pump and an electric pump that can improve driving efficiency and operating efficiency by reducing rotational torque.

  The present invention relates to an inner rotor that is driven to rotate and has external teeth, an outer rotor having internal teeth that mesh with the external teeth, and a rotor housing that rotatably supports the outer rotor by inserting the outer rotor inside. The rotor housing is characterized in that the outer rotor is supported by a rolling bearing.

According to the inscribed gear pump configured as described above, since the outer rotor is supported by the rolling bearing, the outer rotor and the rotor housing are disposed between the outer rotor and the rotor housing as compared with the case of the sliding bearing as in the conventional example. The frictional resistance can be reduced, and the rotational resistance can be reduced. Therefore, the rotational torque when driving the internal gear pump can be reduced.
In addition, the internal gear pump can reduce the rotational resistance between the outer rotor and the rotor housing when the internal bearing is started from a stopped state by the rolling bearing. The rotational torque of the pump can be reduced.

In the above internal gear pump, the rolling bearing is rotatable between a raceway surface formed on an outer peripheral surface of the outer rotor, a fixed raceway surface formed on an inner peripheral surface of the rotor housing, and both raceways. It is preferable to include a plurality of arranged rolling elements.
In this case, since the outer rotor and the rotor housing are respectively configured to serve as a rotating wheel and a fixed wheel of the rolling bearing, the structure can be simplified. Therefore, an increase in the manufacturing cost of the internal gear pump can be suppressed.

In the internal gear pump, the rolling bearing is preferably a needle roller bearing.
In this case, since the rolling bearing can be made compact, it is possible to prevent the diameter of the internal gear pump from increasing.
Furthermore, since the rolling bearing is a needle roller bearing, as described above, when the outer rotor and the rotor housing are also configured to serve as a rotating ring and a fixed ring of the rolling bearing, respectively, It is only necessary to form a cylindrical surface parallel to the axial direction. For example, it is not necessary to form a semicircular raceway surface as in the case of a ball bearing, so both raceway surfaces with respect to the outer rotor and the rotor housing are formed. Processing can be facilitated.

The present invention also provides an inner rotor that is driven to rotate and has external teeth, an outer rotor that has internal teeth that mesh with the external teeth, and the outer rotor is inserted inside to rotatably support the outer rotor. In an electric pump having an internal gear pump including a rotor housing and a motor unit that rotationally drives the inner rotor, the rotor housing supports the outer rotor by a rolling bearing.
In this case, as described above, since the rotational torque is reduced in the internal gear pump, the load on the motor unit is reduced, and the current value of the motor unit can be prevented from excessively increasing. Therefore, the power consumption of the motor unit during operation of the electric pump can be reduced.
Also, when the electric pump is started from a stopped state, the load on the motor unit is reduced by the internal gear pump. Therefore, the inrush current generated when starting the electric pump can be suppressed, and adverse effects on other electronic devices can be eliminated.

As described above, according to the internal gear pump of the present invention, since the rotational torque is reduced, the driving efficiency can be improved.
Moreover, according to the electric pump of the present invention, the load on the motor unit can be reduced and the power consumption can be reduced by using the internal gear pump. As a result, the operation efficiency as an electric pump can be improved.

  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 pump according to an embodiment of the present invention. The electric pump 10 is used as a pump for pumping lubricating oil in a transmission such as an automobile that requires only a relatively low discharge pressure, and includes a motor unit 20 and a pump unit 30.

  The motor unit 20 includes a metal motor housing 21 formed in a bottomed cylindrical shape, a main shaft 22 that is rotatably disposed as an output shaft of the motor unit 20 and drives the pump unit 30, and the main shaft 22. And a stator 24 fixed to the inner peripheral surface of the motor housing 21 so as to face the rotor 23 with a slight gap therebetween. .

  A rolling bearing 25 is fixed to the bottom of the motor housing 21 and supports one end of the main shaft 22. The other end portion of the main shaft 22 is supported by a rolling bearing 33h attached to the pump portion 30 while being connected to the pump portion 30 attached so as to close the opening of the motor housing 21 with a sealing member 26 in a sealed state. Yes.

The pump unit 30 includes a rotor housing body 33 that is directly attached to the motor housing 21, and a lid 34 that is sealed to the rotor housing body 33 by a bolt member 34a while being sealed by a seal member 33a. A housing 31 is provided.
The rotor housing main body 33 is formed to be recessed in the thickness direction (the axial direction of the main shaft 22), and an end surface in contact with the lid portion 34 is a recess 33c that houses an inner rotor 35 and an outer rotor 36 described later. 33b side. The recess 33 c is formed in a cylindrical shape that is eccentric with respect to the axis of the main shaft 22. A through hole 33f is formed in the center of the bottom surface 33e of the recess 33c so as to penetrate in the thickness direction of the rotor housing body 33 (the axial direction of the main shaft 22) toward the motor unit 20 side. The main shaft 22 is inserted into the through hole 33f, and the seal member 33g for sealing between the main shaft 22 and the rotor housing main body 33 is provided at the end of the through hole 33f on the motor unit 20 side. A rolling bearing 33h is attached.

  2 is a cross-sectional view taken along the line II-II in FIG. The pump portion 30 constitutes a trochoid pump, and is connected to a spline 22a formed at the other end of the main shaft 22 so as to be integrally rotatable, and is driven to rotate by the motor portion 20 and has an inner rotor 35 having external teeth 35a. The outer rotor 36 having the inner teeth 36a meshing with the outer teeth 35a, the rotor housing body 33 formed with the recess 33c (FIG. 1) into which the outer rotor 36 is inserted, the cylindrical inner peripheral surface 33d of the recess 33c and the outer And a rolling bearing portion 37 interposed between the outer peripheral surface of the rotor 36.

The rolling bearing portion 37 includes a rotating raceway surface 37a formed on the outer peripheral surface of the outer rotor 36, a fixed raceway surface 37b formed on the cylindrical inner peripheral surface 33d, and a plurality of rolling raceways disposed between both raceways. Needle roller 37c as a rolling element, and a retainer 37d that holds the needle roller 37c at regular intervals in the circumferential direction to constitute a needle roller bearing.
By the rolling bearing portion 37, the rotor housing body 33 supports the outer rotor 36 inserted into the recess 33 c so as to be rotatable with respect to the main shaft 22.

Further, since the outer rotor 36 and the rotor housing body 33 are respectively configured to serve as a rotating wheel and a fixed ring in the rolling bearing portion 37, for example, the outer rotor 36 is supported using a rolling bearing having a normal inner and outer ring. Compared to the case, the number of parts can be reduced, and the structure can be simplified. Therefore, an increase in manufacturing cost of the pump unit 30 can be suppressed.
Moreover, since the rolling bearing part 37 comprises the needle roller bearing, it can be made compact. Therefore, it is possible to prevent the diameter of the pump portion 30 from becoming extremely large compared to the conventional example by having the rolling bearing portion 37.
Further, since the rolling bearing portion 37 is a needle roller bearing, the outer rotor 36 and the rotor housing main body 33 are each configured as a rotating wheel and a fixed ring of the rolling bearing portion 37 as described above. The surface may be formed in a cylindrical surface parallel to the axial direction. For example, it is not necessary to form a semicircular raceway surface as in the case of a ball bearing. Both the raceway surfaces 37a and 37b can be easily processed.

  When the inner rotor 35 is rotationally driven by the motor unit 20, the outer rotor 36 meshing with the inner rotor 35 rotates in an eccentric state with respect to the main shaft 22. At this time, a pumping action is generated by the volume change of the space formed by the external teeth 35a and the internal teeth 36a. Lubricating oil is sucked between an inner rotor 35 and an outer rotor 36 from a suction port (not shown), and lubricating oil is discharged from a discharge port (not shown).

According to the present embodiment configured as described above, the pump portion 30 supports the outer rotor 36 by the rolling bearing portion 37, so that the outer rotor 36 is compared with the case of the sliding bearing as in the conventional example. And the rotor housing body 33 can be reduced in frictional resistance, and the rotational resistance can be reduced. Accordingly, the rotational torque when the pump unit 30 is driven can be reduced, and the driving efficiency can be improved.
In addition, even when the pump unit 30 is in a stopped state, the rolling bearing unit 37 reduces the rotational resistance between the outer rotor 36 and the rotor housing body 33 when the pump unit 30 starts to be driven from the stopped state. Therefore, the rotational torque of the pump unit 30 at the start of driving can be reduced.

  The inventors of the present application conducted a verification test using a trochoid pump having a rated discharge pressure of 0.2 MPa and a basic discharge amount of 1.5 cc / min. As a result, when the outer rotor is supported by the sliding bearing as in the conventional example, the shaft torque required to rotate the inner rotor while maintaining the basic discharge amount is 0.05 N.m. m, whereas in this embodiment, the shaft torque is 0.04 N.m. It has been confirmed that the driving efficiency is improved by 20% or more.

Moreover, according to the electric pump 10 of this embodiment, since the rotational torque of the pump part 30 is reduced, the load on the motor part 20 is reduced, and the current value of the motor part 20 is prevented from excessively increasing. be able to. Therefore, the power consumption of the motor unit 20 during operation of the electric pump 10 can be reduced, and the operation efficiency can be improved.
Furthermore, when the electric pump 10 is started from a stopped state, the load on the motor unit 20 is reduced by the pump unit 30. Therefore, inrush current generated when the electric pump 10 is started can be suppressed, and adverse effects on other electronic devices of the vehicle to which the electric pump 10 is attached can be eliminated.

In addition, this invention is not limited only to the said embodiment. For example, as the rolling bearing portion 37, a rolling bearing having a normal inner and outer ring can be used by fitting the outer ring into the recess 33c of the rotor housing body and fitting the inner ring to the outer peripheral surface of the outer rotor. Further, in the present embodiment, a needle roller bearing is configured as the rolling bearing portion 37, but other types of rolling bearings such as a ball bearing and a cylindrical roller bearing can also be configured.
In the above embodiment, the internal gear pump driven by the motor unit is shown. However, the internal gear pump can be applied to an internal gear pump driven by another power source, for example.
Further, the use of the internal gear pump and the electric pump of the present invention is not limited to the pressure feeding of the lubricating oil in the transmission. For example, as a fuel pump of an internal combustion engine or other general industrial equipment The present invention can also be applied to an internal gear pump that is used.

It is sectional drawing which shows the structure of the electric pump which is one Embodiment of this invention. It is the II-II sectional view taken on the line in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electric pump 20 Motor part 30 Pump part 31 Rotor housing 35 Inner rotor 35a Outer tooth 36 Outer rotor 36a Inner tooth 37 Rolling bearing part 37a Rotating raceway surface 37b Fixed raceway surface 37c Needle roller (rolling element)

Claims (4)

An inner rotor that is rotationally driven and has external teeth; an outer rotor that has internal teeth that mesh with the external teeth; and a rotor housing in which the outer rotor is inserted and rotatably supports the outer rotor; In the internal gear pump with
The internal gear pump, wherein the rotor housing supports the outer rotor by a rolling bearing.   The rolling bearing includes a rotating raceway surface formed on an outer peripheral surface of the outer rotor, a fixed raceway surface formed on the inner side of the rotor housing, and a plurality of rolling elements arranged to be freely rollable between both raceway surfaces. An internal gear pump according to claim 1.   The internal gear pump according to claim 1, wherein the rolling bearing is a needle roller bearing. An inner rotor that is driven to rotate and has outer teeth; an outer rotor having inner teeth that mesh with the outer teeth; and a rotor housing in which the outer rotor is inserted to rotatably support the outer rotor. An internal gear pump,
In an electric pump having a motor unit that rotationally drives the inner rotor,
The electric pump, wherein the rotor housing supports the outer rotor by a rolling bearing.

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