JPH11351154A - Internal gear pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal gear pump requiring a less number of parts and machining processes and causing less friction. SOLUTION: An internal gear pump includes a pump housing 11, an annular outer rotor 17 rotatably held in the pump housing 11 and an inner rotor 19 rotatably held in the pump housing 11 in an eccentric relation to the outer rotor 17 and having an external gear portion 18 formed on the outer periphery to be engaged with an internal gear portion 15 formed on the inner periphery of the outer rotor 17. It also includes an annular side plate 21 integrally formed on the outer rotor 17 abutting to the side end of the inner rotor 19 on the opposite side of one side end of the inner rotor 19 put in slide contact with the pump housing 11 and energizing means 22, 23 for thrusting the side plate 21 against the side end of the inner rotor 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal gear pump having an annular outer rotor and an inner rotor which meshes eccentrically with the outer rotor.

[0002]

2. Description of the Related Art In an internal gear pump in which an annular outer rotor having an internal gear portion on an inner peripheral surface and an inner rotor having an outer peripheral surface with the internal gear portion of the outer rotor are eccentrically engaged. In order to improve the pump efficiency, it is important to reduce the leakage of the hydraulic fluid from the sliding contact surface between the side end surface of the rotor and the pump housing,
As a countermeasure for this, for example, Japanese Patent Laid-Open No. 4-125687
And Japanese Unexamined Patent Publication No. 7-102928 are known.

The inscribed oil pump disclosed in Japanese Patent Application Laid-Open No. 4-125687 is formed on the outer rotor by rotatably holding the outer peripheral side of the outer rotor by a plurality of rotor holding members screwed to the pump housing. The inner rotor is sandwiched between the side plate portion and the pump housing.

In an oil pump disclosed in Japanese Patent Application Laid-Open No. 7-102929, an outer rotor and an inner rotor are housed in an oil pump case, and the outer pump and the inner rotor are formed by an oil pump case and a rotary cover screwed to the oil pump case. Is held.

[0005]

Problems to be Solved by the Invention
The conventional inscribed oil pump disclosed in Japanese Patent Application Publication No. 7-75, requires a plurality of rotor holding members to be arranged along the outer circumference of the outer rotor, so that the number of parts is large and it takes time to adjust the assembly. was there.

Further, the conventional oil pump disclosed in Japanese Patent Application Laid-Open No. 7-102929 has a structure in which the rotary cover slides on the respective side end surfaces of the inner rotor and the outer rotor. It is necessary to perform lightening processing on the rotary cover for reduction, and there is a problem that the number of processing steps is increased.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an internal gear pump having a small number of parts and a small number of processing steps and a small friction.

[0008]

According to the present invention, an internal gear pump according to the present invention has a pump housing, an annular outer rotor rotatably held with respect to the pump housing, and an annular outer rotor. An inner rotor having an external gear portion formed on an outer peripheral surface thereof, which is rotatably held by the pump housing in an eccentric state with respect to the outer rotor and meshes with an internal gear portion formed on an inner peripheral surface of the outer rotor. An annular side plate portion formed integrally with the outer rotor and abutting on a side end surface of the inner rotor opposite to one side end surface of the inner rotor slidingly contacting the pump housing; Biasing means for pressing a portion against the side end surface of the inner rotor.

According to the present invention, the outer rotor rotates together with the inner gear of the outer rotor while the external gear of the inner rotor meshes with the rotation of the inner rotor, thereby generating a pumping action. Also, the outer rotor has its side plate pressed against the side end surface of the inner rotor by the urging means, but the gap between the outer rotor and the side end surface of the inner rotor changes according to the pressure change of the working fluid, and the leakage amount increases as the pressure of the working fluid increases. And the change in the discharge pressure is suppressed as a result.

[0010]

In the internal gear pump according to the present invention, as in claim 2, the biasing means includes an elastic member having one end pressed against the outer rotor, and the pressing means fixed to the pump housing. The elastic member may have a spring receiver against which the other end is pressed. In this case, the elastic member may be an unequal-pitch coil spring.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which an internal gear pump according to the present invention is applied to a lubricating oil supply pump for a vehicle engine will be described.
Although described in detail with reference to FIGS. 1 to 3, the present invention is not limited to such an embodiment, and can be applied to technologies in other fields that include similar problems.

FIG. 1 shows the internal structure of this embodiment with the pump cover removed, and FIG. 2 shows its cross-sectional structure taken along the line II-II. That is, a pump housing 11 into which a crankshaft of a vehicle engine (not shown) is inserted in a penetrating state is provided with a pump body 14 having a stepped hole having a large diameter portion 12 and a small diameter portion 13, And a pump cover (not shown) integrally joined through fixing screws (not shown). However, a pump cover is not essential in the present invention, and there is no particular problem even if a configuration in which this pump cover is omitted is adopted.

The large-diameter portion 12 of the stepped hole has an internal gear 1
An annular outer rotor 17 having an inner rotor 5 and a flange 16 formed on the inner and outer circumferences is rotatably supported, and the outer rotor 17 is provided on the small-diameter portion 13 of the stepped hole which is eccentric to the large-diameter portion 12. An inner rotor 19 having an external gear portion 18 meshing with the internal gear portion 15 is rotatably supported, and one side end surface of the outer rotor 17 and the inner rotor 19 has a seat surface 20 with a stepped hole. Is in contact with. As is well known, the number of teeth of the external gear portion 18 of the inner rotor 19 relative to the number of teeth of the internal gear portion 15 of the outer rotor 17 is set smaller, inner rotor 19, i.e. with respect to the rotational axis C _I of the crankshaft The rotation axis C _O of the outer rotor 17
Becomes eccentric.

On the other end face side of the outer rotor 17,
An annular side plate portion 21 that can abut on the other side end surface of the inner rotor 19 is integrally formed.
Is held between the side plate 21 and the seating surface 20 of the stepped hole. An annular spring receiver 22 is press-fitted to the open end side of the large-diameter portion 12 of the stepped hole, and is integrally fixed to the pump body 14. An unequal pitch coil spring 23 as an elastic member is interposed between the spring receiver 22 and a side end surface of the flange portion 16 of the outer rotor 17. The portion 21 is pressed against the other side end surface of the inner rotor 19.

In this embodiment, the urging means of the present invention is constituted by the spring receiver 22 and the unequal-pitch coil spring 23. However, the above-described pump cover can be used as a spring receiver. In this case, the spring support 2 described above is used.
There is no need to press-fit 2 into the large diameter portion 12 of the stepped hole.

Uneven pitch coil spring 2 in this embodiment
As shown in FIG. 3 showing the relationship between the amount of flexure and the load, the increase rate of the amount of flexure changes at the boundary of the initial set spring force F, that is, the rate of change in flexure under a light load state is high. The rate of change of the deflection in the state is set to be larger than that, so that the resistance when the unequal-pitch coil spring 23 and the spring receiver 22 are attached to the large-diameter portion 12 of the pump body 14 can be reduced. Can be improved.

On the other hand, with respect to a plane including the rotation axes C _I and C _O of the outer rotor 17 and the inner rotor 19, the suction port 24 and the discharge port 25 for the working fluid, that is, the lubricating oil in this embodiment, are connected to the outer rotor 17 and the inner rotor 19. Are formed in the pump body 14 at intervals along the meshing portion with the pump body 14. Further, an engagement hole 27 having a modified cross section corresponding to the crankshaft, that is, a pair of flat portions 26 is formed in a central portion of the inner rotor 19 which engages with the crankshaft and rotates integrally therewith.

Therefore, when the inner rotor 19 is driven counterclockwise in FIG. 1 via the crankshaft, the outer rotor 17 having the internal gear portion 15 meshed with the external gear portion 18 of the inner rotor 19 rotates together with The lubricating oil in the port 24 is sequentially pumped into the discharge port 25 from a gap formed between the external gear 18 of the inner rotor 19 and the internal gear 15 of the outer rotor 17.

In this case, since the discharge pressure of the lubricating oil is low when the crankshaft rotates at a low speed, the outer rotor 17 is urged toward the pump body 14 by the spring force of the unequal pitch coil spring 23, and the seat surface 20 and the outer rotor 17 A predetermined side clearance is maintained between the inner rotor 19 and one side end surface of the inner rotor 19, and between the side plate portion 21 of the outer rotor 17 and the other side end surface of the inner rotor 19, respectively.
Although it has a normal discharge performance, when the rotation of the crankshaft increases, the discharge pressure of the lubricating oil also increases. Therefore, when the discharge pressure exceeds the initial set spring force of the unequal pitch coil spring 23, the unequal pitch coil spring 23 As a result, the outer rotor 17 is displaced toward the spring receiver 22 with a displacement amount proportional to the discharge pressure of the lubricating oil, and the above-described side clearance increases with respect to the initial value. Increases, the amount of lubricating oil discharged from the discharge port 25 decreases,
A predetermined discharge pressure is maintained.

The lubricating oil leaked from the above-described side clearance temporarily enters an oil seal chamber (not shown) formed between the crankshaft and the pump body 14 through a fitting gap between the small diameter portion 13 and the inner rotor 19. After being temporarily stored, the oil is returned to an oil pan (not shown) through a drain hole (not shown) communicating with the oil seal chamber.

[0021]

According to the internal gear pump of the present invention, an annular side plate portion abutting on the side end surface of the inner rotor is formed integrally with the outer rotor, and this side plate portion is pressed against the side end surface of the inner rotor by the urging means. Since the gap between the side plate and the inner rotor changes according to the discharge pressure and the discharge pressure increases, the amount of leakage increases.As a result, there is no need to provide a relief valve or the like, and the number of parts is reduced. Together, a low-cost and compact internal gear pump can be obtained. In addition, since there is no needless work, a highly efficient internal gear pump can be provided.

Further, when the elastic members are unequal pitch coil springs, the load at the time of mounting can be reduced, and the assembling property can be improved.

[Brief description of the drawings]

FIG. 1 is a front view of an embodiment of an internal gear pump according to the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a graph showing the relationship between the amount of deflection and the load of the unequal pitch coil spring used in the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Pump housing 15 Internal gear 16 Flange 17 Outer rotor 18 External gear 19 Inner rotor 21 Side plate 22 Spring support 23 Unequal pitch coil spring

Claims (3)

[Claims] A pump housing; an annular outer rotor rotatably held with respect to the pump housing; and an inner peripheral surface of the outer rotor rotatably held by the pump housing in an eccentric state with respect to the outer rotor. An internal gear pump having an external gear portion meshing with the internal gear portion formed on the outer rotor and an inner rotor formed on the outer peripheral surface, the external gear portion being integrally formed with the outer rotor and slidingly contacting the pump housing. An annular side plate portion abutting on a side end surface of the inner rotor opposite to one side end surface of the inner rotor; and a biasing means for pressing the side plate portion against the side end surface of the inner rotor. Internal gear pump. 2. The device according to claim 1, wherein the biasing means includes an elastic member having one end pressed against the outer rotor, and a spring receiver fixed to the pump housing and pressed against the other end of the elastic member. 2. The internal gear pump according to 1. 3. The internal gear pump according to claim 2, wherein the elastic member is an unequal pitch coil spring.