JP3194044B2 - Oil pump structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an oil pump, and more particularly to an oil pump case in which an outer rotor and an inner rotor are accommodated and provided, and a suction port and a discharge port communicating with a pump chamber formed by the outer rotor and the inner rotor. The present invention relates to a structure of a trochoid type oil pump provided with a port and a port respectively.

[0002]

2. Description of the Related Art Conventional oil pumps include a gear pump for pumping oil by meshing a driving gear and a driven gear, and a trochoid pump having an inner rotor and an outer rotor.

As shown in FIG. 7, a trochoid pump, for example, a trochoid type oil pump 102 accommodates an outer rotor 106 and an inner rotor 112 in a housing (not shown) of an oil pump case 104 and a rotor cover (not shown). It is attached to prevent falling off. Further, the oil pump 102 has an inner tooth portion (not shown) of the inner rotor 112 and an outer tooth portion (not shown) of the outer rotor 106 formed by a trochoid curve.
Are assembled in the oil pump case 104 with their axes different from each other.

Further, the number of inner side teeth of the inner rotor 112 is configured to be one less than the number of outer side teeth of the outer rotor 106, and by rotating the inner rotor 112, the outer rotor 106 becomes the same as the inner rotor 112. When the pump chamber 114 rotates, the pump chamber 114 formed by the inner tooth portion of the inner rotor 112 and the outer tooth portion of the outer rotor 106 changes the capacity to perform a pumping operation.

[0005] Such an oil pump discharges oil from a suction port to a discharge port side, and is smaller and simpler in structure than other types of oil pumps of the same capacity.
Further, since the meshing noise is small, it is widely used as a lubrication pump for a vehicle, an oil pump for a transmission, and the like.

The structure of the oil pump is disclosed in Japanese Utility Model Laid-Open No. 4-107423. The oil pump disclosed in this publication is provided with an opening that opens toward the volume chamber immediately before the confinement section on the suction chamber side of the return passage of the lubricating oil from the discharge chamber to the suction chamber, and is generated in a high-speed rotation region. In order to prevent cavitation, lubricating oil can be supplied from the discharge chamber side to the volume chamber immediately before the containment section.

[0007] Another example is disclosed in Japanese Utility Model Laid-Open No. 5-27209. In the oil pump disclosed in this publication, when the inner rotor is fitted to the end of the crankshaft via the spacer, both the spacer and the inner rotor are formed of a sintered metal, and a plurality of Are arranged in the axial direction to prevent generation of concentrated stress acting on the inner rotor in the radial direction, and to enable high-precision coupling.

[0008]

By the way, in the structure of the conventional oil pump, when the inner rotor is further rotated from the position where the volume of the pump chamber is maximized to connect the discharge port with the pump chamber, the high pressure discharge port is used. When the oil suddenly flows back into the pump chamber, a water hammer phenomenon is caused and noise is generated.

[0009]

In order to eliminate the above-mentioned disadvantages, the present invention provides an oil pump case in which an outer rotor and an inner rotor are housed and communicates with a pump chamber formed by the outer rotor and the inner rotor. In the oil pump provided with a suction port and a discharge port respectively, a discharge port is formed in the oil pump case, and a rotor cover located on the opposite side to the discharge port with the outer rotor and the inner rotor interposed therebetween is earlier than the discharge port. A sub-discharge port communicating with the pump chamber is provided, and the sub-discharge port is formed in a rectangular recess so as to gradually increase the amount of oil communication between the sub-discharge port and the pump chamber.

In an oil pump, an outer pump and an inner rotor are housed and provided in an oil pump case, and a suction port and a discharge port communicating with a pump chamber formed by the outer rotor and the inner rotor are provided. A groove is provided at one of the inner rotor and the front part in the rotation direction at a position earlier than the discharge port so as to communicate with the pump chamber, and the front side in the rotation direction is gradually increased so that the oil communication between the groove and the pump chamber gradually increases. The groove is formed so that the depth of the groove becomes shallower as the mode shifts to.

[0011]

According to the invention described above, when the oil pump is driven, the sub-portion formed in the rectangular recess is formed so that the amount of oil communication between the sub-discharge port and the pump chamber gradually increases earlier than the discharge port. The discharge port is connected to the pump chamber to prevent backflow of oil from the high-pressure discharge port to the pump chamber, to prevent a water hammer phenomenon from occurring, and to reduce noise.

Also, when the oil pump is driven, the depth of the groove is shifted to one of the outer rotor and the inner rotor so as to gradually increase the oil communication between the groove and the pump chamber in the rotational direction. The groove formed so as to be shallower and provided in the front part in the rotation direction communicates with the pump chamber earlier than the discharge port, and avoids reverse flow of oil from the high pressure discharge port to the pump chamber,
The occurrence of the water hammer phenomenon is prevented, and the noise is reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIGS. 1 and 2 show a first embodiment of the present invention. 1 and 2, reference numeral 2 denotes a trochoid type oil pump which is a high-pressure displacement type.

The oil pump 2 includes an oil pump case 4 mounted on a mounting portion (not shown), an outer rotor 6 rotatably mounted on a housing 4 a provided on the oil pump case 4, and an outer side of the outer rotor 6. An inner rotor 12 that is driven to rotate by a drive shaft (not shown) by meshing the inner teeth 10 with the teeth 8.

The oil pump case 4 has a suction port that communicates with a pump chamber 14 that is formed by the outer side teeth 8 of the outer rotor 6 and the inner side teeth 10 of the inner rotor 12 moving while expanding and contracting in the rotation direction. 16 and a discharge port 18 are respectively formed.

When the outer rotor 6 and the inner rotor 12 are mounted on the oil pump case 4, a rotor cover 20 for preventing the outer rotor 6 and the inner rotor 12 from falling off is used.

As shown in FIG. 1, a discharge port 18 is formed in the oil pump case 4, and the discharge port 18 is sandwiched between the outer rotor 6 and the inner rotor 12.
A sub-discharge port 22 for communicating with the pump chamber 14 earlier than the discharge port 18 is provided on the rotor cover 20 located on the opposite side of the rotor cover 20, and the amount of oil communication between the sub-discharge port 22 and the pump chamber 14 gradually increases. The sub-discharge port 22 is formed in a rectangular recess so as to increase the number.

More specifically, as shown in FIG. 1, the sub-discharge port 22 has a rectangular recess 24 formed in the rotor cover 20 so that when the rotor cover 20 is mounted, the sub-discharge port 2
2 is formed, and is formed so as to have a passage sectional area smaller than the passage sectional area of the discharge port 18.

As shown in FIG. 1, the sub-discharge port 22 is provided on the rotor cover 20 opposite to the discharge port 18 with the outer rotor 6 and the inner rotor 12 therebetween. Are extended in a direction opposite to the rotation direction of the outer rotor 6 and the inner rotor 12.

Next, the operation will be described.

When the oil pump 2 is driven, the outer rotor 6 and the inner rotor 12 in the oil pump case 4 are moved.
The pump chamber 14 is formed by the completion of the closing in between, and the pressure in the pump chamber 14 is increased by the pump action.

Then, with the rotation of the inner rotor 12, the sub-discharge port 22 first communicates with the pump chamber 14 earlier than the discharge port 18. At this time, since the passage cross-sectional area of the sub-discharge port 22 is smaller than the passage cross-sectional area of the discharge port 18, the amount of oil movement is small, and the amount of oil communication between the sub-discharge port 22 and the pump chamber 14 is gradually reduced. And the pressure rise is slow, that is, a sudden pressure change is efficiently mitigated.

When the rotation of the inner rotor 12 advances, the discharge port 18 communicates with the pump chamber 14. However, even if the discharge port 18 communicates with the pump chamber 14 where the pressure has increased, there is no rapid backflow of oil.

As a result, a rapid change in pressure can be efficiently reduced by the sub-discharge port 22 provided on the rotor cover 20 side so that the discharge port 18 can communicate with the pump chamber 14 at an early stage. Oil can be reliably prevented from flowing back to the pump chamber 14, and the water hammer phenomenon does not occur and noise can be reduced.

Further, when the sub-discharge port 22 is formed, the sub-discharge port 22 can be realized only by forming the recess 24 of the rectangular concave portion in the rotor cover 20, so that the structure is simple, the production is easy, and the cost is low. It can be maintained and is economically advantageous.

FIGS. 3 to 5 show a second embodiment of the present invention. In the second embodiment, portions that perform the same functions as those in the first embodiment will be described with the same reference numerals.

A feature of the second embodiment is that one of the outer rotor 6 and the inner rotor 12 is communicated with the pump chamber 14 earlier than the discharge port 18 at, for example, a front portion in the rotation direction of the outer rotor 6. Groove 3
0 is provided.

That is, the groove 30 is formed in the manner shown in FIGS.
As shown in FIG. 5, the outer peripheral teeth 8 are formed to have a predetermined length and an arc shape, to have a passage cross-sectional area smaller than that of the discharge port 18, and to be formed between all the outer side teeth portions 8.

Then, a sudden pressure change can be efficiently mitigated by the groove 30 provided at the front portion in the rotation direction of the outer rotor 6 so as to communicate with the pump chamber 14 earlier than the discharge port 18. As in the case of the first embodiment, the backflow of oil from the discharge port 18 to the pump chamber 14 can be reliably prevented, so that the water hammer phenomenon does not occur and noise can be reduced.

Further, when the groove portion 30 is formed, it can be realized only by forming an arc-shaped groove in the outer rotor 6, so that the structure is simple, the production is easy, the cost can be maintained at low cost, and the economy can be reduced. It is economically advantageous.

Further, as shown in FIG. 6, one of the outer rotor 6 and the inner rotor 12, for example, a front portion in the rotation direction of the inner tooth portion 10 of the inner rotor 12 communicates with the pump chamber 14 earlier than the discharge port 18. A groove 40 may be provided.

This groove 40 has the same depth or the groove 4
In order to gradually increase the amount of oil communication between 0 and the pump chamber, it is possible to form a shape in which the depth gradually decreases as the position moves forward in the rotation direction, that is, the depth of the groove portion 40 becomes shallower.

Then, as in the case of the above-described second embodiment, a sudden change in pressure can be efficiently mitigated, and backflow of oil from the discharge port to the pump chamber can be reliably prevented. The hammer phenomenon does not occur, the noise can be reduced, and the configuration is simple, the manufacturing is easy, the cost can be kept low, and it is economically advantageous.

[0035]

As described above in detail, according to the present invention, the discharge port is formed in the oil pump case of the oil pump, and the discharge port is formed on the rotor cover located on the opposite side to the discharge port with respect to the outer rotor and the inner rotor. A sub-discharge port is provided to communicate with the pump chamber earlier, and the sub-discharge port is formed in a rectangular recess so as to gradually increase the amount of oil communication between the sub-discharge port and the pump chamber. As a result, a sudden change in pressure can be efficiently mitigated, the backflow of oil from the discharge port to the pump chamber can be reliably prevented, and the water hammer phenomenon does not occur and noise can be reduced.

Further, a groove is provided in one of the outer rotor and the inner rotor of the oil pump at a position on the front side in the rotation direction to communicate with the pump chamber earlier than the discharge port, and the amount of oil communication between the groove and the pump chamber gradually increases. The groove is formed so that the depth of the groove becomes shallower as it moves to the front side in the rotation direction so as to increase, so that the groove communicates with the pump chamber earlier than the discharge port, and it is possible to efficiently mitigate sudden pressure changes. Therefore, the backflow of oil from the discharge port to the pump chamber can be reliably prevented, so that the water hammer phenomenon does not occur and noise can be reduced.

[Brief description of the drawings]

FIG. 1 is a central longitudinal sectional view of an oil pump in FIG. 2 showing a first embodiment of the present invention.

FIG. 2 is a front view of the oil pump.

FIG. 3 is a front view of an oil pump showing a second embodiment of the present invention.

FIG. 4 is a front view of an outer rotor.

FIG. 5 is a schematic sectional view taken along line VV in FIG. 4;

FIG. 6 is a front view of an inner rotor showing another embodiment of the second embodiment of the present invention.

FIG. 7 is a front view of an oil pump showing a conventional technique of the present invention.

[Explanation of symbols]

 2 Oil Pump 4 Oil Pump Case 4a Housing 6 Outer Rotor 8 Outer Side Teeth 10 Inner Side Teeth 12 Inner Rotor 14 Pump Chamber 16 Suction Port 18 Discharge Port 20 Rotor Cover 22 Sub Discharge Port 24 Concave

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01M 1/02 F04C 2/10 341

Claims (2)

(57) [Claims] 1. An oil pump in which an oil pump case accommodates and provides an outer rotor and an inner rotor, and further includes a suction port and a discharge port communicating with a pump chamber formed by the outer rotor and the inner rotor. A discharge port is formed in the case, and a sub-discharge port is provided on the rotor cover positioned opposite to the discharge port with the outer rotor and the inner rotor interposed therebetween, the sub-discharge port being connected to the pump chamber earlier than the discharge port. The structure of the oil pump, wherein the sub-discharge port is formed in a rectangular recess so that the amount of oil communication with the pump chamber gradually increases. 2. An oil pump in which an outer pump and an inner rotor are accommodated and provided in an oil pump case and a suction port and a discharge port are provided respectively, which communicate with a pump chamber formed by the outer rotor and the inner rotor. A groove is provided in one of the inner rotor and the front part in the rotation direction at a position in the rotation direction earlier than the discharge port, so that the oil communication between the groove and the pump chamber is gradually increased on the front side in the rotation direction. The structure of the oil pump, characterized in that the depth of the groove portion is reduced as the position shifts.