JP2000186677A - Oil pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of pumping efficiency and suppress abrupt pressure fluctuation in a pump chamber. SOLUTION: A drive gear 12 and a driven gear 13 are stored in a pump chamber composed of a first housing and a second housing. Capacity parts 131 to 140 thereof are opened to a discharge port 26 formed at least one of the first and second housings to form discharge capacity parts 30, while they are opened to a suction port 27 to form suction capacity parts 31. A maximum capacity part 136 is formed between the suction capacity part 31 and the discharge capacity part 30. A recession 33 having an elastic member 38 which promotes communication between the discharge port 30 and the maximum capacity part 136 in proportion to discharge pressure is formed on an end wall 32 of the discharge port 30 at its rear side in a rotational direction. Alternatively, a projection 35 of elastic material which retards the communication between the suction port 31 and the maximum capacity part 136 according to the suction pressure is formed on an end wall 34 of the suction port 31 at its front side in a rotational direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal gear type oil pump.

[0002]

2. Description of the Related Art An internal gear type oil pump, for example, an internal gear having a trochoid tooth profile is inscribed with an external gear having a drive shaft eccentric and having one less number of teeth, the external gear is a drive gear, and the internal gear is a driven gear. In an oil pump configured as
At the meshing portion of the drive gear and the driven gear, a suction volume portion whose volume sequentially increases in the rotation direction due to the rotation of the two and a discharge volume portion whose volume sequentially decreases in the rotation direction are formed.

[0003] The pump case has a facing inner wall in contact with the axial end surfaces of the drive gear and the driven gear, and an inner peripheral wall inscribing the outer peripheral surface of the driven gear. Of the first housing and the second housing. The first and second housings accommodate a drive gear and a driven gear in the pump chamber, and have a suction port formed on at least one of the opposed inner walls and opening to a suction volume portion and a discharge port opening to a discharge volume portion and suctioning. A suction passage and a discharge passage communicating with the port and the discharge port are formed.

In some cases, a maximum volume is formed between the suction volume and the discharge volume. In this maximum volume part, the reduced pressure state when the suction volume part sucks oil and the high pressure state when the discharge volume part discharges oil are repeated, causing the cavitation and liquid hammer phenomenon to increase the operating noise. There is. In order to reduce the operation noise, the suction volume section and the discharge volume section may be always in communication,
This reduces pump efficiency. Therefore, Japanese Patent Laid-Open No. 9-2
In Japanese Patent Application Laid-Open No. 96716, as shown in FIG. 7, the outer rotor 1 (driven gear) and the inner rotor 2 (drive gear) have an even number of teeth. It is described that, for example, a chamfered portion 4 that connects adjacent individual volume portions 3 is provided.

[0005] In the oil pump of the above publication, by providing the chamfered portion 4 with one tooth skip, one end in the circumferential direction (rotational direction) of the volumetric portion 3 is adjacent to the volumetric portion 3 by the chamfered portion 4.
And the other end is isolated from the volume 3 adjacent to the opposite side, so that the suction volume composed of the volume 3 communicating with the suction port 5 and the volume 3 communicating with the discharge port 6
The maximum volume 3 'formed in the middle of the discharge volume is not connected to the suction volume and the discharge volume at the same time to prevent cavitation and liquid hammer and to prevent a decrease in pump efficiency. Trying to.

[0006]

However, even in the oil pump described in the above publication, the maximum volume 3 'is moved by the rotation of the drive gear 2 and the driven gear 1, so that as shown in FIG. When the maximum volume 3 'communicates with the suction port 5 when the maximum volume 3' communicates with the discharge volume at the end wall in the rotation direction of the discharge port 6, the suction port and the discharge port are connected to each other. Are communicated, and the pump efficiency is reduced. Similarly, when the maximum volume portion 3 ′ communicates with the suction port 5 at the end wall portion behind the suction port 5 in the rotation direction, and when the maximum volume portion 3 ′ communicates with the discharge port 6 by the chamfered portion 4, The suction port and the discharge port communicate with each other.

It is an object of the present invention to provide an oil pump which reliably prevents cavitation and liquid hammer without lowering the pump efficiency.

[0008]

In order to solve the above problems, the inventors of the present invention have made various studies and found that the state of communication between the discharge port and the suction port depends on the end wall on the rear side in the rotation direction of the discharge port. The present invention has been completed by noting that a maximum volume is caused by communication between the discharge port and the suction port at the end wall on the rotation direction front side of the suction port.

That is, the oil pump of the present invention has a drive gear having a predetermined number of external teeth, and a plurality of suction volumes between the drive gear and internal gears having one more tooth than the drive gear. The driven gear in which the drive gear is inscribed so as to form one maximum volume in the middle of the plurality of discharge volume portions and the suction volume portion and the discharge volume portion, and abuts against the axial end faces of the drive gear and the driven gear. A drive chamber and a driven gear are housed in a pump chamber which is defined by an opposing inner wall and an inner peripheral wall which inscribes an outer peripheral surface of the driven gear. A discharge port opened to the discharge volume portion was formed, and a suction passage communicating with the suction port and a discharge passage communicating with the discharge port were formed. (1) The oil pump including the first and second housings, (1) an end wall portion in the rotation direction rear side of the discharge port located in the discharge volume portion, and an intermediate position in the width direction intermediate position of the discharge port. Forming a recess extending rearward in the rotational direction so as to communicate the maximum volume portion and the discharge port, and attaching an elastic member to the bottom surface of the recess; (2) the suction port located in the suction volume portion An end wall on the front side in the rotation direction of the suction port and extending rearward in the rotation direction of the suction port so as to shut off the maximum volume portion and the suction port at a widthwise intermediate position of the suction port; At least one of: a portion formed entirely of an elastic member, or a portion provided with an elastic member stuck near the opening surface of the suction port is provided at a portion near the opening surface of the suction port. .

[0010]

According to the oil pump of the present invention, the depression and the elastic member provided on the end wall on the rear side in the rotation direction of the discharge port are provided with an elastic member. It functions to release the pressure as soon as possible in proportion to the size of. In addition, when the recess communicates with the maximum volume portion of the discharge port, the end wall portion on the rotation direction front side of the suction port can be in a phase that is not located at the maximum volume portion, so that the suction port and the discharge port can simultaneously have the maximum volume. It is possible to suppress a decrease in pump efficiency and prevent cavitation and liquid hammer phenomenon without communicating with the section.

The protrusion, which extends rearward in the rotation direction of the suction port and has an elastic member attached to at least a portion near the opening surface of the suction port, prevents a change in the suction volume from a small to a large volume change. The pressure is delayed in proportion to the pressure of the suction volume, and the pressure is gradually reduced as the pressure of the suction volume decreases. As a result, the suction port and the discharge port do not communicate with the maximum volume at the same time, so that a decrease in pump efficiency can be suppressed and a rapid pressure fluctuation (cavitation or liquid hammer phenomenon) in the pump chamber can be prevented.

Further, when the elastic member on the discharge port side is provided with the recess affixed to the bottom surface and the protrusion on the suction port side, the communication between the suction port and the discharge port via the maximum volume is more reliably avoided. In addition, cavitation and liquid hammer can be prevented.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an oil pump according to the present invention,
The protrusion on the suction port side needs to be provided on both the first housing and the second housing. Further, the recess on the discharge port side where the elastic member is attached to the bottom surface may be provided in at least one of the first housing and the second housing.

The projection on the suction port side delays the communication between the suction port and the maximum volume portion, and changes the volume of the suction volume portion as slowly as possible. The protrusion on the suction port side is provided with an elastic member at a portion near the opening surface of the suction port,
A projection main body integral with the first and second housings as the pedestal of the elastic member may extend in the axial direction from the bottom surface of the suction port. According to this configuration, the thickness of the elastic member is reduced, and the responsiveness of the suction volume to the reduced pressure state is improved.

[0015] In the oil pump of the present invention, the recess in which the elastic member is stuck on the bottom surface is sufficiently long on the rear side in the rotational direction together with the elastic member. May be larger. In this way, by sufficiently lengthening the recess in which the elastic member is attached, the discharge volume portion and the maximum volume portion can be communicated at an early stage with a larger excess discharge pressure.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An oil pump according to the present invention will be specifically described with reference to embodiments shown in the drawings. First Embodiment As shown in FIG. 1, a basic configuration of an oil pump according to a first embodiment includes a drive gear 12 made of an iron-based sintered metal having external teeth 11 having a predetermined number of trochoid teeth, The gear 12 includes a driven gear 14 having internal teeth 13 made of the same material in which the external teeth 11 of the gear 12 are inscribed, and a first housing 15 and a second housing 16 made of aluminum die cast and connected in the axial direction.

As shown in FIG. 4, the external teeth 11 of the drive gear 12 and the internal teeth 13 of the driven gear 14 have one less external tooth 11 than the internal teeth 13 of the driven gear 14. According to the relationship of the number of teeth, the drive gear 12 is eccentric with respect to the center of the driven gear 14 between the outer teeth 11 and the inner teeth 13 of the drive gear 12 and the driven gear 14 so that a predetermined number of the volume portions 131 to 140 Are formed in the rotation direction A (FIG. 4).

As shown in FIGS. 1 and 2, the first housing 15 has a disk-shaped flange portion 18 having a central concave portion 17 for rotatably housing the driven gear 14 in which the drive gear 12 is inscribed, A boss 20 having a shaft hole 19 eccentric to the recess 17. A drive shaft (not shown) that supports the drive gear 12 so that it cannot rotate relatively is inserted into the shaft hole 19.

An outer peripheral recess 21 (FIG. 1) is formed on the outer periphery of the central recess 17 so as to fit with the outer peripheral portion 20 of the second housing 16 concentrically with the shaft hole 11. A bolt hole 22 and a bolt hole 23 for attachment to an external device are formed on the bottom surface of the outer peripheral concave portion 21 and the outer peripheral side thereof. Second housing 16
A bearing 25 having a shaft hole 24 through which the shaft member extending to the opposite side to the first housing 15 is inserted;
And the outer peripheral portion 20 that fits into the outer peripheral concave portion 21 and closes the central concave portion 17.

A pump chamber for accommodating the drive gear 12 and the driven gear 14 is defined by the central recess 17 of the first housing 15 and the outer peripheral portion 20 of the second housing 16. The center surface 20a of the outer peripheral portion 20 of the housing 16 (the portion inside the hatched portion in FIG. 3) is
4 are opposed inner walls that contact the respective axial end surfaces.

As shown in FIG. 2, a discharge port 26 and a suction port 2 are provided on the bottom of the central recess 17 of the first housing 15.
7, a discharge recess 28 facing the discharge port 26 of the first housing 15 and a suction recess 28 facing the suction port 27 of the first housing 15, as shown in FIG. 29 are formed.

As shown in FIG. 4, the discharge port 26 and the discharge recess 28 which face each other in the axial direction are
140 are aligned with the volumes 137 to 140,
Opening into the volume parts 137 to 140
0 is the discharge volume 30. One of the discharge port 26 and the discharge recess 28 is a closed chamber, and the other is connected to a discharge passage (not shown).

As shown in FIG. 4, the suction port 27 and the suction recess 29 which face each other in the axial direction are aligned with the capacities 131 to 135 of the capacities 131 to 140 in the circumferential direction. 135 and the volume 131
To 135 are suction volume portions 31. The suction port 29 is a closed chamber as shown in FIG. 1, and the suction port 27 communicates with the suction passage 30.

Further, as shown in FIG.
6, suction recess 28, suction port 27 and suction recess 29
The volume portion 136 that is not aligned with the above becomes the maximum volume portion in the present invention. The configuration of the present embodiment is characterized in that, as shown in FIG. 2, FIG. 4 and FIG.
The end wall portion 32 on the rear side in the rotation direction A of the discharge port 26 located at the intermediate position in the width direction of the discharge port 26, on the rear side in the rotation direction A communicating the maximum volume portion 136 and the discharge port 26. An extended depression 33 is formed. An elastic member 38 made of rubber or the like is provided on the bottom of the hollow 33.
Has been pasted. In this case, the upper surface of the elastic member 38
It is located below the opening surface of the discharge port 26 by a predetermined dimension B. The dimension B is set very small.

As shown in FIGS. 2, 4 and 5,
End wall portion 34 on the front side in rotation direction A of suction port 27
In addition, a protrusion 35 made of an elastic member and extending rearward in the rotation direction A that blocks the maximum volume portion 136 and the suction port 27 is formed at a middle position in the width direction of the suction port 27. Similarly, as shown in FIGS. 3 and 4, the end wall 36 on the front side in the rotation direction A of the suction recess 29 and the suction recess 29
The maximum volume 136 and the suction recess 29
A protrusion 37 made of an elastic member extending rearward in the rotation direction A is formed to block the movement. (Operation) The oil pump according to the above-described embodiment has a drive gear 1
The driven gear 14 rotates with the rotation of 2, and the transition from the state in which the suction volume section 31 communicates with the maximum volume section 136 to the state in which the discharge volume section 30 communicates with the maximum volume section 136 is repeated, and the pump action is performed. Will be

When the suction volume 31 communicates with the maximum volume 136, in the oil pump of the present embodiment, the suction volume 31 is increased by the protrusions 35 and 37 of the elastic member.
The timing of communication with the suction volume 36 can be delayed in proportion to the suction pressure (the transition to a state in which the suction volume 31 communicates with the maximum volume 136 is performed as gradually as possible in proportion to the suction pressure).

Further, the suction volume 31 is the maximum volume 136.
The discharge port 26 and the discharge recess 2
Eight recesses 33 do not communicate with the discharge port 26. Therefore, the discharge port 26 and the discharge recess 28 do not communicate with the suction port 27 and the suction recess 29. On the other hand, in a state where the discharge volume section 30 communicates with the maximum volume section 136, the suction port 27 and the discharge concave
9 is blocked from the maximum volume 136, and the discharge port 2
6 and the discharge recess 28 do not communicate with the suction port 27 and the suction recess 29, and the discharge port 26
In addition, the discharge concave portion 28 and the maximum volume portion 136 communicate with each other. Also in this case, the deformation of the elastic member 38 of the recess 33 increases in proportion to the discharge pressure, and the discharge port 26 and the discharge recess 28 can communicate with the maximum volume portion 136 early in proportion to the discharge pressure. it can.

As described above, in the oil pump of this embodiment,
When the suction port 27 and the suction recess 29 communicate with the maximum volume portion 136, the communication is delayed in proportion to the suction pressure, and the discharge port 26 and the discharge recess 28
6 communicates with the discharge pressure earlier in time in proportion to the discharge pressure, and even at that time, the suction port 27 and the suction recess 29 are surely shut off from the maximum volume 136, so that the discharge pressure becomes excessive. The liquid hammer phenomenon and cavitation in which the pressure in the maximum volume portion 136 changes suddenly can be avoided. Further, in a normal pressure state, a state in which the suction port 27 and the suction recess 29 communicate with the discharge port 26 and the discharge recess 28 can be reliably avoided, and the pump efficiency can be improved.

(Second Embodiment) The third embodiment shown in FIG.
The elastic member 38 and the recess 33 provided on the wall end portion 32 of the discharge port 26 extend rearward in the rotation direction A from the first embodiment, and the elastic member 38 provided on the bottom surface of the recess 33 is attached to the upper surface of the discharge port 26. The opening 38 has a portion 38a having a gap B 'with respect to the opening surface, and a portion 38b facing the opening surface.

By extending the recess 33 and the elastic member 38 rearward in the rotation direction A as in the second embodiment, a more excessive discharge pressure can be released at an early stage. That is, when the discharge pressure is relatively low, the discharge pressure is reduced by the portion 38a along the opening surface of the discharge port 26, and when the discharge pressure is further excessive, the portion 38b can be released by deformation.

[0031]

As described above, according to the oil pump of the present invention, the end wall portion on the suction port side or the discharge port side has the largest volume portion formed between the discharge volume portion and the suction volume portion. The timing at which the maximum volume portion and the discharge volume portion or the suction volume portion communicate with each other at the end wall portion can be finely adjusted, and cavitation and liquid hammer can be prevented without lowering the pump efficiency.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing an oil pump of the present invention.

FIG. 2 is a configuration diagram of a first housing used in the first embodiment.

FIG. 3 is a configuration diagram of a first housing used in the first embodiment.

FIG. 4 is an explanatory diagram showing a discharge volume section, a suction volume section, and a maximum volume section formed in the oil pump of the first embodiment.

FIG. 5 is a sectional view of the first housing taken along line II of FIG. 2;

FIG. 6 is a sectional view of a first housing showing a second embodiment.

FIG. 7 is an explanatory view showing a discharge volume section, a suction volume section, and a maximum volume section formed in a conventional oil pump.

[Explanation of symbols]

12 drive gear, 14 driven gear, 15 first housing, 16 second housing, 26, 28 discharge port, 27, 29 suction recess, 31 suction volume, 3
0: discharge volume portion, 32, 34: end wall portion, 33: depression, 35: protrusion, 38: elastic member, 136: maximum volume portion.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G013 BB19 BB24 BD42 3H041 AA02 BB04 CC17 CC19 CC20 DD04 DD12 DD13 DD17 DD18 DD33

Claims (2)

[Claims] A drive gear having a predetermined number of external teeth;
A plurality of suction volumes, a plurality of discharge volumes, and one maximum volume in the middle of the suction and discharge volumes between the drive gear and internal gears having one more tooth than the drive gear. A driven gear in which the drive gear is inscribed so as to be formed; a pump chamber which is defined by an opposing inner wall in contact with each axial end face of the drive gear and the driven gear; A suction port that accommodates the driven gear and that is formed on at least one of the opposed inner walls with a plurality of suction ports opened to the suction volume and a plurality of discharge ports opened in the discharge volume, and a suction passage communicating with the suction port; An oil pump including first and second housings each having a discharge passage communicating with the discharge port. (1) The oil pump is located in the discharge volume section. An end wall portion at the rear side in the rotation direction of the discharge port, and a recess extending rearward in the rotation direction at the intermediate position in the width direction of the discharge port so as to communicate the maximum volume portion and the discharge port. And an elastic member attached to the bottom surface of the depression. (2) The end wall of the suction port located in the suction volume portion at the front side in the rotation direction and at the intermediate position in the width direction of the suction port. It extends rearward in the rotational direction of the suction port so as to shut off the maximum volume portion and the suction port. At least a portion near the opening surface of the suction port is entirely made of an elastic member or elastically formed near the opening surface of the suction port. An oil pump, comprising: at least one of a protrusion provided with a member. 2. The recess according to claim 1, wherein the recess having an elastic member attached to the bottom surface extends more rearward in the rotation direction than the protrusion of the suction port extends rearward in the rotation direction. Oil pump.