JPH0736142Y2 - Vane pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a vane pump used in a power steering device of an automobile or the like, and more particularly to a vane pump in which noise generated by cavitation is reduced.

(Prior Art) Most of the pumps recently adopted as power sources for power steering devices are vane pumps. Its features are small size, light weight, quietness and simple device,
It is widely used because it has the advantages of withstanding high-speed rotation, good volume efficiency at low-speed rotation, and sufficient reliability.

In this type of conventional vane pump, in order to match the center of the cam surface of the cam ring with the center of the rotor, a hole is precisely cut in the housing, and a hole is also accurately cut in the front plate to correspond to this hole. It was processed.
Therefore, if an error occurs when cutting any one of these holes and holes, the centers of the cam ring, the cam surface, and the rotor will be slightly displaced from each other, and the pump will be moved in this state. When assembled, the drive shaft vibrates along with the rotor during operation, causing vibration and noise.

Therefore, the present applicant has previously proposed a vane pump having the following structure in order to solve such a problem (see Japanese Patent Application No. 61-117066). In this vane pump, attached to the knock pin, the cam ring is attached to the rear cover,
The projection end of the drive shaft that inserts the rotor is fitted into the bearing portion of the rear cover so that the center of the cam surface of the cam ring and the center of the rotor are aligned with each other so as to prevent generation of noise due to vibration.

In addition, in order to prevent the cam ring and rotor from slipping in the axial direction of the drive shaft, the side plate is inserted into the drive shaft so that the cam ring and rotor come into contact with the same side surfaces of the cam ring and urge them toward the rear cover. The other end surface of the plate is biased by a spring that abuts the inner surface of the housing.

(Problems to be solved by the invention) By the way, in the vane pump according to such a prior application, as shown in FIG. 5, the clearance (area of the shaft chamber 33 formed by the housing 31 and the drive shaft 32) )
Therefore, when the working fluid leaks from both side surfaces of the rotor (both side surfaces contacting the rear cover and the side plate), the working fluid passes through the shaft spline portion and the shaft chamber 33 and returns from the shield lens hole 33 to the suction port. In this case, the working fluid leaking from both side surfaces of the rotor and discharged to the shaft chamber 33 may cause cavitation in a member forming the shaft chamber 33 to cause noise, and improvement in this respect is desired.

(Object of the Invention) Therefore, the present invention reduces the clearance between the housing of the shaft chamber and the drive shaft to prevent cavitation due to a sudden discharge of the working fluid when the working fluid leaks from the side surface of the rotor, and prevents the vane pump. The purpose is to reduce noise.

(Means for Solving Problems) Therefore, the present invention has a cam ring vane rotor
It has a side plate and has a shaft hole connected to the connecting hole of the rotor, and has a bearing and a shaft seal on the opening end side of the shaft hole to the outside, and the inside of the shaft seal is the suction passage of the pump. A housing that is connected to the housing, a cover plate that closes the opening of the housing, and a shaft chamber that is inserted into the shaft hole to form a shaft chamber, and is rotatably supported by the bearing and the cover plate. In a vane pump including a drive shaft for rotationally driving the rotor together, the working oil leaking from the side surface of the rotor is returned to the suction passage through the shaft chamber. The aperture resistance portion is formed by setting the clearance between the shaft chamber surface and the drive shaft to a predetermined small value.

(Operation) In the present invention, the shaft chamber surface forming the shaft chamber portion of the housing is brought close to the drive shaft to set a small clearance between the housing and the drive shaft in the shaft chamber,
A diaphragm resistance portion is formed. Therefore, the occurrence of cavitation when the working fluid leaks from the side surface of the rotor is prevented, and the noise of the vane pump is reduced.

(Example) Hereinafter, the present invention will be described with reference to the drawings.

1 to 4 are views showing an embodiment of a vane pump according to the present invention.

First, the configuration will be described. FIG. 1 is a longitudinal sectional view of the vane pump in the axial direction, and FIG. 2 is a sectional view taken along line II-II of FIG. In these drawings, reference numeral 1 denotes a vane pump, which includes a housing 2 and a cover plate 15, and the cover plate 15 is fixed to a front surface 2a of the housing 2 with bolts 16. The housing 2 is formed with a concave portion (cam ring housing portion) 7 opening to the front surface 2a, and a shaft hole provided so as to open to the center of the concave portion 7 from the side opposite to the front surface 2a. A housing-side suction passage 4 is provided in parallel with the recess 7 from the front surface 2a, and a control valve accommodating hole orthogonal to the suction passage 4 is provided at the end of the suction passage 4.
A control valve 3 for controlling the discharge flow rate is housed in this housing hole.

Although not shown, the control valve storage hole communicates with the bottom of the recess 7.

In addition, in the housing-side suction passage 4, the housing 2
Open to the side of, and connected to the source of hydraulic oil (not shown),
The suction hole 5 is opened, and the seal drain hole 6 communicating with the shaft hole is opened. The cover plate 15 is attached to the housing 2 as described above, the bearing portion 15c is provided in the central portion of the attachment surface, one end communicates with the housing-side intake passage 4, and the other end is connected to each pump suction port described later. A cover-side suction passage 15a is formed that communicates with a suction port that opens in the section.

Reference numeral 10 denotes a drive shaft, which penetrates an axial hole of the housing 2 and a projecting end portion 10a thereof is rotatably supported by a bearing portion 15c provided on the cover plate 15 and a rear end portion thereof is an outer concave portion of the housing 2. It is rotatably supported by bearings 21 provided on 20. Then, a spline portion is formed in a portion of the drive shaft 10 following the projecting end portion 10a so as to be spline-coupled with a connecting hole 9b of the rotor 9 which will be described later.
A spline portion and a screw portion are formed at the rear end portion for attaching a pulley or the like for receiving a drive input.

In addition, 19 is a shaft seal, and 22 is a C ring for preventing the bearing 21 from coming off.

A shaft chamber 17 is formed between the shaft hole of the housing 2 and the drive shaft 10.
Is communicated with the recess 7 and is sealed with the shaft seal 19 while being communicated with the housing-side suction passage 4 through the seal drain hole 6. A spring 12c, a side plate 12, a cam ring 11 and a rotor 9 are sequentially inserted into the recess 7 from the bottom.

The outer periphery of the cam ring 11 is non-rotatably coupled to the inner wall of the recess 7 of the housing 2 via a pin, and a cam surface 11a is formed on the inner periphery thereof.

A rotor 9 is inserted into the cam ring 11, a plurality of vanes 8 are held in the rotor 9 so as to be retractable in the radial direction, and a back pressure passage 9a provided on the base end side of the vane 8 is provided.
Each vane 8 is urged outward in the radial direction by the pump discharge pressure introduced into the vane 8, and the tip of each vane 8 is brought into contact with the cam surface 11a of the cam ring 11 by this urging force. Has become. In addition, the inner circumference of the rotor 9 has a connecting hole.
It is formed in 9b, is spline-coupled with the drive shaft 10, and is rotationally driven by the drive shaft 10.

On the side of the cam ring 11 and the rotor 9, on the other hand,
The side plate 12 comes into contact with the side plate 12, and the side plate 12 is pressed against the cam ring 11 and the rotor 9 by the pressure of the high pressure chamber 14 formed by the spring 12c and the side plate 12 and the recess 7. The mounting surface is in contact. Therefore, the rotor 9, the cam ring 11, the side plate 12, and the cover plate 15 form a pump working space, which is partitioned by the vanes 8 to form a plurality of working chambers 13.

Therefore, when the vane 8 slides into and out of the cam surface 11a of the cam ring 11 due to the rotation of the rotor 9, the working chamber 13 gradually increases and decreases in volume to suck working oil into the working chamber 13 and suck the working chamber 13 into the working chamber. Discharge from 13. The suction port 15b (the suction port on the side plate side is not shown in the drawing) is provided in the cover plate 15 and the side plate 12 in the section where the working chamber 13 increases in volume as the rotor 9 rotates.
The two are communicated with each other through port holes 11b and 11c provided in 11. ) Is formed, the discharge port 12 is formed on the side plate 12 in the section where the working chamber 13 decreases in volume as the rotor 9 rotates.
a is formed.

Further, in this embodiment, a part of the inner surface of the shaft hole of the housing 2 forming the shaft chamber 17 is brought close to the drive shaft 10, that is, the shaft chamber surface 18 having extremely small clearance therebetween is provided. .

Therefore, when the working oil leaking from both side surfaces of the rotor 9 (both side surfaces contacting the side plate 12 and the cover plate 15) returns to the housing suction passage 4 through the connecting hole 9b, the shaft chamber 17 and the shield lens hole 6, Between the shaft chamber surface 18 and the drive shaft 10, throttling resistance is generated with respect to the flow of hydraulic fluid.

Next, the operation will be described.

When the drive shaft 10 is rotationally driven from outside the drawing, hydraulic oil is drawn into the working chamber 13 in the intake section from the supply source (not shown) through the intake hole 5, the housing intake passage 4, the cover intake passage 15a and the intake port 15b. Then, the working oil whose pressure has been increased from the working chamber 13 in the discharge section is introduced into the control valve 3 through the discharge port 12a, the discharge passage 12b and the high pressure chamber 14. This hydraulic oil is supplied to a power spring or the like while its flow rate is controlled by the control valve 3. Further, the pressurized hydraulic oil leaks through both side surfaces of the rotor 9 (both side surfaces contacting the cover plate 15 and the side plate 12), but the shaft chamber surface 18 of the housing 2 and the drive shaft in the shaft chamber 17 are leaked. Since the clearance of 10 is small, the amount of hydraulic oil filled in the axial direction between the back pressure passage 9a and the connecting hole 9b to the shaft chamber 17 is significantly reduced, that is, the clearance in the shaft chamber 17 is reduced. Since the liquid tightness is improved and the pressure difference between the working chamber 13 and the upstream side of the shaft chamber 17 is small, the leaked hydraulic oil is not rapidly released into the shaft chamber 17, and therefore the liquid Turbulence does not easily occur in the flow, and as a result, cavitation in the shaft chamber 17 is suppressed, and noise of the vane pump can be significantly reduced.

To explain this, we turn to FIG.

FIG. 3 shows the noise level of the vane pump. The solid line shows the present embodiment and the dotted line shows the conventional example. This noise level is measured under the following conditions.

Pump speed 1000 rpm Pump discharge pressure 30 Kgf / cm ^{2 In} the figure, the noise level is about 50 (dBA) and the frequency is about 4 to 6 (KHz) in the conventional example where the clearance of the shaft chamber 33 is large. In this embodiment with a small clearance of about 40 (dBA) and a frequency of about 4 to 6 (KHz), about 10
(DBA) The volume is getting lower. In addition, the noise level is significantly reduced over the entire frequency band of 1 to 8 (KHz).

Further, FIG. 4 shows the noise level measured when the rotation speed of the vane pump is changed. The ● mark shows the conventional example and the ○ mark shows the present embodiment. The measurement rotation speed is measured at 3 points of 1000 rpm, 1500 rpm, 2000 rpm,
The noise level at each measurement point is about 4 to 6 (dBA) in the present embodiment, as compared with the conventional example, and the noise level is significantly reduced.

〔effect〕

As explained in detail above, according to the present invention, among others,
A part of the shaft chamber forms a shaft chamber surface that is close to the drive shaft, and the diaphragm resistance portion is formed with the clearance between the shaft chamber surface and the drive shaft set to a predetermined small value. It is possible to prevent the occurrence of cavitation in the shaft chamber when the hydraulic oil leaks from the side surface of the rotor to the suction passage through the shaft chamber. Moreover, this can reduce the noise of the vane pump.

[Brief description of drawings]

1 to 4 are views showing an embodiment of a vane pump according to the present invention. FIG. 1 is a sectional view of a main part showing the structure of the vane pump, and FIG. 2 is a sectional view taken along line II-II of FIG. FIG. 3 is a diagram showing the relationship between the noise level and the frequency of the conventional vane pump and the vane pump of the present embodiment at the rotational speed of 1000 rpm, and FIG. 4 is the conventional vane pump and the present embodiment when the rotational speed is variable. FIG. 5 is a diagram showing the relationship between the noise level of a vane pump and the number of revolutions, and FIG. 1 ... Vane pump, 2 ... Housing, 4 ... Suction passage, 9 ... Rotor, 10 ... Drive shaft, 11 ... Cam ring, 12 ... Side plate, 17 ... Shaft chamber, 18 ...
Axle chamber surface, 19 ...... Axial seal.

Claims (1)

[Scope of utility model registration request] Claims: 1. A cam ring vane rotor side plate is built in, and a shaft hole connected to the connecting hole of the rotor is provided, and a bearing and a shaft seal are provided on the opening end side of the shaft hole to the outside. A shaft chamber is formed between the housing, which is provided inside the shaft seal and is connected to the suction passage of the pump, the cover plate which closes the opening of the housing, and the shaft hole which is inserted into the shaft hole. A vane pump that includes the bearing and a drive shaft that is rotatably supported by the cover plate and that rotationally drives the rotor, and that recirculates the working oil leaking from the rotor side surface to the suction passage through the shaft chamber, A part of the shaft chamber is formed close to the drive shaft, and the throttle resistor is formed so that the clearance between the shaft chamber surface and the drive shaft is a predetermined small value. Vane pump which is characterized.