JPS6119991A - Oil pump - Google Patents

Abstract

PURPOSE:To aim at preventing abnormal noise, heat generation and so on from occurring, in an opening part to the inside of a housing of a discharge chamber, by making length in a circumferential direction smaller than ever before, insomuch that discharge capacity in a pump is securable, while making a pressure receiving area, where oil pressure inside the discharge chamber acts on both rotors, smaller as well. CONSTITUTION:A circumferential partition position at the side of a sealed space 21 in an opening part to a space 13 inside a housing of a discharge chamber 18 is set down to P, and making a state that the sealed space 21 becomes maximum a basis, circumferential length size l of the discharge chamber 18 is set between circumferential length size l1 up to a position P1 where gears 14a and 15a contact in the first and circumferential length size l2 up to a position where these gears 14a and 15a contact in the third, and the length size in the circumferential direction of the discharge chamber 19 is set to be smaller than ever before. In this connection, the reason that the said l is set to be larger than l2 is to secure discharge capacity in a pump of the discharge chamber 18. With this constitution aforesaid, a pressure receiving area of oil pressure acting on both rotors 14 and 15 becomes smaller whereby tooth surface pressure drops, thus abnormal noise, friction, heat generation, etc., are all preventable from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an oil pump, more specifically, it is used for lubricating an automobile engine, and is used to lubricate an inner rotor (
This relates to a trochoidal oil pump that performs pumping action through engagement between external teeth on the driving side (driving side) and internal teeth on the outer rotor (driven side) (prior art) The basic structure of this type of oil pump is as follows: JP-A-5Ill-
As disclosed in Japanese Patent Application Laid-open No. 35212 or Japanese Patent Application Laid-Open No. 58-70014, an outer rotor having internal teeth is rotatably fitted into a housing having an internal space, and engaged with the internal teeth of the outer rotor. An inner rotor with external teeth is arranged eccentrically with respect to an outer rotor, and the volume of the sealed space formed between the two rotors changes due to the driving force of a rotating shaft connected to the inner rotor. The housing further has a suction chamber and a discharge chamber that open into the interior space. The number of teeth on the inner rotor is set to be one less than the number of teeth on the outer rotor.
The oil pump disclosed in Japanese Patent Publication No. 35212 is an example of an inner rotor with four teeth and an outer rotor with five teeth, while JP-A-58-70014 discloses an example of a multi-tooth rotor. . The attached FIG. 4 shows a trochoidal oil pump having a multi-toothed rotor, in which the outer rotor 50
An inner rotor 51 is eccentrically arranged inside the inner rotor 5.
1, the inner teeth 50a of the outer rotor 50 and the outer teeth Sta of the inner rotor 51 engage with each other, and a sealed space ( The volume of the pump (shaded area in the figure) 53 changes, and a pumping action is performed. The housing that accommodates both rotors is further formed with a suction chamber 54 and a discharge chamber 55 (both chambers are indicated by broken lines in the figure), and both chambers open into the internal space of the housing. The inflowing oil is discharged from the sealed space 53 and flows out into the discharge chamber 55 by the aforementioned pump action. In addition, 56 and 57 show the respective ports of the suction chamber 54 and the discharge chamber 55.

(Problems to be Solved by the Invention) In the conventional oil pump disclosed in FIG. Based on the state where the space 53 is maximum, the inner tooth 50a and the outer tooth 5 are placed first along the rotation direction.
It corresponds to the contact point P of 1a, and has a length of 11 in the circumferential direction. In this way, since the opening portion of the discharge chamber 55 into the housing is formed up to the position P close to the sealed space 53, that is, the circumferential length dimension β1 of the discharge chamber 55 is set to be relatively large. , the pressure-receiving area on which the discharge pressure generated in the discharge chamber 55 acts on both rotors 50 and 51 becomes larger. Therefore, the surface pressure on the tooth surfaces at the meshing part between the internal teeth 50a and the external teeth 51a increases, causing friction between the outer rotor (internal teeth) 50 and the inner rotor (external teeth) 51, or between the housing and the outer rotor. Friction between the pumps caused abnormal noise, heat generation due to wear, etc., and the performance of the pump was significantly impaired.

Therefore, the technical problem of the present invention is to reduce the circumferential length of the opening of the discharge chamber into the housing to such an extent that the discharge capacity of the pump is not impaired.

[Structure of the invention]

(Means to solve the problem) The technical measures taken to achieve the above technical problem are:
Basically, the position of the circumferential partition toward the sealed space side at the opening of the discharge chamber to the internal space of the housing is the first position of both teeth along the rotational direction of the rotor, with the sealed space being at its maximum. Between the contact position and the third position where both teeth contact,
It means that it is set.

(Function) By employing the above technical means, the circumferential length of the discharge chamber is reduced, and the pressure-receiving area on which the oil pressure in the discharge chamber acts on both rotors is reduced. Therefore, the force acting on both rotors is reduced, the tooth surface pressure at the meshing portion of both teeth is reduced, and the generation of abnormal noise, friction heat generation, etc. due to friction is prevented.

(Example) Hereinafter, an example that specifically implements the technical means of the present invention will be described with reference to the accompanying drawings.

The oil pump (first embodiment) 10 shown in FIGS. 1 and 2 (A-A sectional view in FIG. 1) has a pump housing 11 fixed to an engine block. A cover 12 is fixed to the upper end opening.

An outer rotor 14 is rotatably fitted in the internal space 13 of the housing 11, and an inner rotor 15 having a rotation axis eccentric from the rotation axis of the outer rotor 14 is disposed within the outer rotor 14.

be accommodated in. Internal teeth 14a of the outer rotor 14;
The shaft hole 16 of the inner rotor 15 is configured to engage with the external teeth 15a of the inner rotor 15, and a rotating shaft (e.g., a crankshaft) driven by the engine and pivotally supported by the housing 11 is coupled to the shaft hole 16 of the inner rotor 15. Ru. The bottoms of both rotors 14 , 15 form the same plane and lie deeper than the bottom, i.e. in the interior space 13 of the housing 11 .
An oil suction chamber 17 is provided in the housing 11 so as to open to the
and discharge chambers 18 are formed, respectively, and 19.20 indicates a boat for each chamber. A sealed space (shaded area in the figure) 21 is formed between both rotors 14 and 15, that is, an internal tooth 14a and an external tooth 15
Two pairs of adjacent a.

A sealed space is formed between the tooth tips, and a pumping action is performed by changing the volume of the sealed space 21. Oil flowing into the suction chamber 17 flows out into the discharge chamber 18 by the pumping action of the sealed space 21.

Now, based on the condition that the circumferential partition position P on the sealed space 21 side at the opening of the discharge chamber 18 to the housing internal space 13 is the maximum sealed space 21, both rotors 14
, 15, both teeth 14a, 15a are first along the rotational direction of the teeth 14a, 15a.
It is set between the position P where the two teeth 14a and 15a are in contact with each other and the third position P where both the teeth 14a and 15a are in contact with each other. In this embodiment, the circumferential partition position P1 is the second position where both teeth 14a and 15a come into contact. In this way, the circumferential length dimension β of the discharge chamber 18 is determined by the first circumferential length dimension 11 up to the position P1 where both teeth 14a and 15a contact, and the third dimension is the circumferential direction length dimension β up to the position P1 where both teeth 14a and 15a contact. The circumferential length dimension up to the point P where it touches! It is set between the factory and the factory. This circumferential length dimension l
The reason why it is set larger than y is to ensure the discharge capacity of the pump of the discharge chamber 18. In addition, the present invention is based on the inner loaf 1.
This can be effectively applied to an oil pump having a multi-toothed rotor having at least 5 #Js.

FIG. 3 shows a second embodiment of the present invention, in which an enlarged chamber 22 is provided up to the back pressure of the outer rotor 14 to maintain a balance with the internal hydraulic pressure.

In other words, the outer loaf 14 is housed in the housing 11 with a balance between the hydraulic pressure received outward from the discharge chamber 8 and the hydraulic pressure received inward from the expansion chamber 22.

〔Effect of the invention〕

In this way, the length of the discharge chamber of the present invention can be made smaller than the length of the conventional discharge chamber in the circumferential direction. Hydraulic pressure decreases. Therefore, it is possible to prevent noises caused by friction, heat generated by friction, etc., and to greatly improve the durability and performance of the pump.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a first embodiment of an oil pump according to the present invention, FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, and FIG.
This figure corresponds to FIG. 2, and is a sectional view showing a second embodiment of the present invention, and FIG. 4 is a sectional view showing an example of a conventional oil pump.

Claims (1)

[Claims] a pump housing; an outer rotor rotatably fitted into the inner space of the housing; an inner rotor having outer teeth that engage with inner teeth of the outer rotor; In the oil pump, the oil pump has a rotating shaft, a suction chamber and a discharge chamber formed in the housing so as to open into an internal space of the housing, and two adjacent pairs of the internal teeth and the external teeth. Based on the state in which the sealed space formed between the tooth tips of the two rotors is maximized, the circumferential partition position on the sealed space side of the opening of the discharge chamber to the internal space is set between the two rotors. The first position where both the teeth contact and the third position along the rotation direction of the
The oil pump is set between the position where the two teeth are in contact with each other.