JPH06323261A - Oil pump - Google Patents

Abstract

(57) [Abstract] [Purpose] In an oil pump having a superposed assembly structure, the side clearance of the pump rotor is prevented from expanding due to thermal expansion of each member, and the pump weight is reduced. [Constitution] In the oil pump 10, the pump rotor 1
Since the rotors 1 and 12 and the rotor housings 7 and 8 are made of the same material, the side clearance of the pump rotor does not increase even if the pumps are thermally expanded during operation. In addition, the rotor housing is made of high-strength material to match the pump rotor that requires strength,
By forming the cover housings 2 and 3 and the center plate 9 with a lightweight material, it is possible to reduce the weight of the pump without impairing the function of the pump.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil pump structure attached to an engine, and more particularly to an oil pump having a multiple structure in which a plurality of rotor housing portions are partitioned by a center plate (partition wall). is there.

[0002]

2. Description of the Related Art In addition to the one integrally cast around the pump rotor in the housing, a plurality of oil pumps that accommodate a pair of cover housings and pump rotors are arranged side by side between the cover housings. There is a superposed structure that is assembled from the rotor housing and the center plate that separates the rotor housings. According to such a structure, the clearance (side clearance) between the pump rotor and the cover housing or the center plate can be easily kept small by controlling the thickness dimension of each member, and the volumetric efficiency of the pump can be reduced. Can be improved. As an oil pump configured by partitioning a plurality of rotor housing parts with a center plate, for example,
Some are proposed in Japanese Utility Model Publication No. 1-159190. Further, conventionally, there has been a pump rotor formed of a high-strength material such as cast iron, which requires strength, and a housing formed of a light-weight material such as an aluminum alloy for weight reduction of the pump.

[0003]

However, when the pump rotor and the rotor housing are made of different materials in the superposed structure pump, the side clearance is widened due to the difference in thermal expansion between these two members during the operation of the pump. There is a problem that it may end up.

The present invention has been made in view of the above problems and the like, and prevents the side clearance of the pump rotor from expanding due to the thermal expansion of each member and reduces the weight of the pump. The purpose is to provide.

[0005]

To achieve the above object, in the oil pump of the present invention, the pump rotor and the rotor housing are made of the first material, and the cover housing and the center plate are made of the second material. Is forming.

Specifically, the first material is a high-strength material and the second material is a lightweight material.

The oil pump is preferably used as a multiple-type trochoid type pump in which each pump rotor is composed of an outer rotor and an inner rotor inscribed in the outer rotor.

[0008]

In such an oil pump, since the pump rotor and the rotor housing are made of the same material (first material), both members have the same coefficient of thermal expansion. For this reason, the side clearance of the pump rotor does not expand even if both are thermally expanded during the operation of the pump. In addition, the rotor housing is made of a high-strength material in accordance with the pump rotor that requires strength, while the cover housing and the center plate are made of a lightweight material to reduce the pump weight without impairing the function of the pump. be able to.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a trochoidal oil pump 1 according to the present invention. The oil pump 1 has two cover housings (right cover housing 2 and left cover housing 3) arranged on the left and right.

A shaft hole 2a extending in the left-right direction is formed near the vertical center of the right cover housing 2, and a pump shaft 4 is rotatably supported in the shaft hole 2a via a ball bearing 5. There is. A suction port 2b for sucking oil is formed in the lower portion of the right cover housing 2.
A suction passage (first suction passage 2c, second suction passage 2d) extending in two directions is also formed. Further, a discharge port 2e for discharging oil is formed in the upper portion of the right cover housing 2, and a first discharge path 2f and a second discharge path (not shown) connected to this discharge port 2e are also formed. ing.

A shaft hole 3a extending in the left-right direction is formed near the center of the left cover housing 3 in the vertical direction, and the pump shaft 4 is rotatably supported in the shaft hole 3a via a roller bearing 6. ing.
The left end portion of the pump shaft 4 projects to the outside from the shaft hole 3a, and the pump shaft 4 is rotationally driven by the output rotation of the engine applied thereto.
Further, a third suction passage 3b extending in the vertical direction is formed in the lower portion of the left cover housing 3, and a similar third discharge passage 3c is formed in the upper portion.

Between these cover housings 2 and 3,
The two rotor housings (the right rotor housing 7 and the left rotor housing 8 are arranged side by side. That is, the right end portion of the right rotor housing 7 is covered by the right cover housing 2, and the left end portion of the left rotor housing 8 is the left cover housing 3. An inner toothed outer rotor 11 is mounted in each rotor housing 7, 8 as shown in Fig. 2 (however, the left rotor housing 8 is shown in this figure), and the outer rotor 11 is further attached. An outer tooth-shaped inner rotor 12 is disposed inside the rotor 11. The inner rotor 12 is integrally attached to the outer periphery of the pump shaft 4, and the inner rotor 12 is rotated by the rotation of the pump shaft 4. The rotor rotates while inscribed in the rotor 11. The first suction passage 2c is on the right. Open at the bottom right side of the over coater housing 7, the third suction passage 3b is left rotor housing 8
Open at the lower left side of the. In addition, the first discharge passage 2f is
It opens on the right side of the upper part of the right rotor housing 7,
The discharge passage 3c opens at the upper left side surface of the left rotor housing 8.

Then, these rotor housings 7 and 8
The center plate 9 is arranged in between. In this way, the two cover housings 2, 3 and the two rotor housings 7 and 8 and the center plate 9 are bolted to the respective bolt holes 21 which are formed as a single hole at four locations around each member (see FIG. 2). 22 is inserted and assembled as a unit in a superposed manner. As a result, the rotor housings 7 and 8 are partitioned by the center plate 9 to form independent rotor housing portions. Further, the second suction passage 2 is provided above and below the two rotor housings 7 and 8 and the center plate 9, respectively.
A suction side communication passage 23 that communicates d with the third suction passage 3b and a discharge side communication passage 24 that communicates the second discharge passage with the third discharge passage 3c are formed.

The oil pump 1 assembled in this way
Then, as the pump shaft 4 is driven, the oil in the oil tank (not shown) is transferred to the suction passages 2c, 2d,
It is sucked into the low pressure chamber 13 formed between the outer rotor 11 and the inner rotor 12 in the lower portion of each rotor housing 7, 8 via 3b. Then, the sucked oil is pressurized by the meshing of the rotors 11 and 12, and is merged and discharged from the discharge port 2e from the high pressure chamber 14 formed in the upper part of the rotor housings 7 and 8 via the discharge passages 2f and 3c. To be done. The pulsation of the discharge pressure can be suppressed by appropriately shifting the phase of the left and right rotor rotations.

Here, in order to improve the volumetric efficiency of the pump 10, first, a gap is formed between the outer rotor 11 and the inner rotor 12 and the cover housing (2 or 3) and the center plate 9 which are adjacent to the outer rotor 11 and the inner rotor 12. ,
That is, it is necessary to make the side clearance as small as possible. Therefore, in this pump 10, the side clearance is reduced by controlling and adjusting the thickness of each member by face milling such as milling. Also, the rotor housings 7, 8 and the cover housings 2,
By separating 3 and 3 to form a superposed structure, chamfering that creates a gap between the outer rotor 11 and the housing is unnecessary. For this reason,
It is possible to prevent communication between the suction passage and the discharge passage, which also improves the volumetric efficiency.

Further, in the present pump 10, the rotor housings 7 and 8 and the rotors 11 and 12 are made of the same material, specifically, a high-strength material (for example, cast iron) having sufficient strength. There is. As a result, both members thermally expand in the thickness direction at the same ratio, so that the side clearance does not expand due to the heat generated during pump operation. Therefore, the volumetric efficiency can be further improved in combination with the reduction of the side clearance due to the above-mentioned chamfering.

Further, in this pump 10, the cover housings 2 and 3 and the center plate 9 are made of the same lightweight material (for example, aluminum alloy). Thereby, the weight of the entire pump can be reduced.

[0018]

As described above, in the oil pump according to the present invention, the pump rotor and the rotor housing are made of the same material so that both members have the same coefficient of thermal expansion. Therefore, it is possible to prevent an increase in the clearance between the pump rotor and the cover housing and the center plate adjacent to the pump rotor when the pump is operated. Therefore, if this oil pump is used, high volumetric efficiency can be achieved. Further, by forming the pump rotor and the rotor housing with a high-strength material, it is possible to endure high rotation operation, and by forming the cover housing and the center plate with a lightweight material, it is possible to reduce the weight of the entire pump. it can.

[Brief description of drawings]

FIG. 1 is a side sectional view of an oil pump according to the present invention.

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

[Explanation of symbols]

 1 Oil Pump 2,3 Cover Housing 2b Suction Port 2e Discharge Port 4 Pump Shaft 7,8 Rotor Housing 9 Center Plate 11 Outer Rotor 12 Inner Rotor

Claims (3)

[Claims] 1. An oil pump comprising a plurality of rotor housings respectively accommodating pump rotors arranged side by side between a pair of cover housings and partitioning the rotor housings with a center plate. An oil pump, wherein the rotor housing is made of a first material, and the cover housing and the center plate are made of a second material. 2. The oil pump according to claim 1, wherein the first material is a high-strength material and the second material is a lightweight material. 3. The trochoidal pump of the multiple type, wherein each of the pump rotors is composed of an outer rotor and an inner rotor inscribed in the outer rotor. Oil pump.