JPH05133351A - Vane pump - Google Patents

Abstract

PURPOSE:To prevent generation of an impulse wave at the time of delivery by extremely decreasing a pressure difference between both a vane chamber and a delivery port when the vane chamber of a vane pump communicates with the delivery port. CONSTITUTION:A rotational region, where a vane chamber 22 formed between two sheets of vanes 18 is not connected to any port during the time of the vane chamber after disconnected from a suction port 26 till connected to a delivery port 28, is provided in a rotor 14. In this region, a cam shape is formed so as to decrease volume of the vane chamber. A valve unit 36 formed of deformable material is arranged in a cam ring 10 to guide a delivery oil pressure to the outside of this valve unit, and the inside communicates with the inside of the cam ring 10 through a small bore hole. The small bore hole is opened to a rear end of the vane chamber 22 in a position just before the vane chamber 22 communicates with the delivery port 28.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vane pump used in a vehicle power steering system or the like.

[0002]

2. Description of the Related Art As shown in FIG. 6, a vane pump has a cam ring 10 having a substantially elliptical cam surface 100a on its inner circumference.
0, and the rotor 102 rotating in the cam ring 100,
A large number of vanes 10 inserted in the slits formed on the outer peripheral side of the rotor 102 at equal intervals in the circumferential direction so as to be movable back and forth.
4 and a plate (not shown) that holds the cam ring 100 and the rotor 102 from both sides, and each vane 104 is attached to the cam ring 1 as the rotor 102 rotates.
Oil is sucked and discharged through the suction port 108 and the discharge port 110 by increasing or decreasing the volume of the vane chamber 106 formed between two adjacent vanes 104. ..

As shown in FIG. 7, the volume of the vane chamber 106 varies from V _min to V _max depending on the rotation of the rotor 102.
Vary between, sucks oil from the suction port 108 at an increased stroke of the V _max from V _min, and discharges oil from the discharge port 110 in the compression stroke to V _min from V _max. Then, when the vane chamber 106 communicates with the discharge port 110 when the volume of the vane chamber 106 becomes maximum, if there is a difference between the pressure of the discharge port 110 and the pressure in the vane chamber 106, the oil may flow in or There has been a problem that outflow occurs and a shock wave is generated, which causes noise.

FIG. 8 shows a pulsating waveform measured in the pipe following the discharge port 110, and shows the case where the pressure in the discharge port 110 is higher than the pressure in the vane chamber 106. The moment of communication (a),
A rapid pressure drop occurs in (b). When the pressure in the vane chamber 106 is higher than the pressure in the discharge port 110, a rapid pressure increase occurs in (a) and (b), which is the reverse of FIG.

In order to reduce the difference between the pressure in the discharge port and the pressure in the vane chamber as described above, or to avoid a sudden pressure fluctuation by avoiding instantaneous communication, the following method has been conventionally used. It is taken. (1) In order to communicate with the discharge port after increasing the pressure in the vane chamber to the discharge port pressure, a rotor rotation region that does not communicate with either the suction port or the discharge boat is provided after the volume of the vane chamber is maximized, In addition, the cam shape is designed so that the volume of the vane chamber is reduced in this region. That is, the pressure in the vane chamber is increased by performing precompression before starting the discharge. In this case, the boost value is generally about half of the maximum discharge pressure. (2) In order to avoid momentary communication between the discharge port and the vane chamber, use a notch or the like to allow the oil to gradually flow from the discharge port into the vane chamber when the vane chamber approaches the discharge port. Reduce the pressure difference.

[0006]

The vane pump used in the power steering system of an automobile has a discharge pressure of zero.
Since it fluctuates within a range of up to 60 kg / m ² and the pump rotation speed also fluctuates between 700 and 3000 rpm, the above conventional method is effective at a certain discharge pressure or a certain rotation speed, but as it deviates from that value, There was a problem that the effect decreased.

The present invention has been made in order to eliminate the above-mentioned drawbacks, and provides a vane pump that does not generate a shock wave and produces little noise by communicating the two in a state where the pressure in the vane chamber and the pressure in the discharge port are extremely close. The purpose is to do.

[0008]

SUMMARY OF THE INVENTION A vane pump according to the present invention comprises a cam ring having a cam formed on its inner surface, a rotor rotating in the cam ring, and slits formed on the outer circumference of the rotor at equal intervals in the circumferential direction. A vane inserted in the inside of the vane and a plate for holding the cam ring and the rotor from both sides are provided, and the volume of the vane chamber formed between two adjacent vanes is increased or decreased as the rotor rotates. As a result, oil is sucked from the suction port into the vane chamber and discharged through the discharge port, and further, after the volume of the vane chamber becomes maximum,
The vane chamber is provided with a rotor rotation region that does not communicate with either of the ports, and a cam shape that reduces the volume of the vane chamber in this region is provided, and at the position immediately before the vane chamber starts communicating with the discharge port. A valve body made of a deformable material is provided on the cam ring on the rear side in the rotation direction of the vane chamber, the discharge hydraulic pressure is guided to the outside of the valve body, and the inside of the valve body and the inner surface of the cam ring are connected by a small hole. Is.

[0009]

In the vane pump described above, when the vane chamber is precompressed before it communicates with the discharge port and the pressure in the chamber rises, and the pressure in the vane chamber is different from the pressure on the discharge port side, both Due to a slight deformation of the valve element interposed between the two, the pressures of the two are adjusted to substantially equal values.

[0010]

The present invention will be described below with reference to the illustrated embodiments.
FIG. 1 is a cross-sectional view of a main part of a vane pump according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line II-II of the vane pump. A pump body 6 including a front body 2 and a rear body 4 contains a pump cartridge. 8 are accommodated. The pump cartridge 8 has a cam ring 10 having a substantially elliptical cam surface 10a on the inner circumference thereof, a rotor 14 connected to the drive shaft 12 and rotating in the cam ring 10, and a radial slit formed near the outer circumference of the rotor 14. It is provided with a large number of vanes 18 which are inserted into 16 and move back and forth.

The cam ring 10, the rotor 14 and the vanes 18 are sandwiched between the rear body 4 and the side plate 20 arranged in the front body 2, and as the rotor 14 rotates, two adjacent vanes are provided. The volume of the vane chamber 22 formed between 18 is increased or decreased,
From the suction passage 24 and the suction port 26 to the vane chamber 2
2 is sucked into the high pressure chamber 30 through the discharge port 28.

A circular hole 32 is formed on the outer peripheral side of the cam ring 10.
And a valve element 34 made of a deformable material such as rubber is press-fitted into the circular hole 32. The outer side of the valve body 34 communicates with the discharge port 28 via the passages 36 and 37, and the inner side communicates with the inner surface 10a side of the cam ring 10 through a small-diameter hole 38. In addition, 39 is a presser ring.

In the vane pump according to this embodiment, the vane chamber 22 between the two adjacent vanes 18 has the suction port 26.
1 that does not communicate with either the discharge port 28 or the discharge port 28
It has 4 rotation zones. That is, when the vane 18 reaches the position shown by the solid line in FIG. 4, the vane chamber 22 is blocked from the suction port 26, and at this time, the discharge port 28 is still present.
When the vane 18 reaches the position shown by the alternate long and short dash line in FIG.
It communicates with the groove 40. Moreover, the vane chamber 22 has a cam shape in which the volume of the vane chamber 22 is maximized at the position indicated by the solid line and the volume of the vane chamber 22 is gradually compressed while moving to the position indicated by the alternate long and short dash line.

The inside of the valve element 34 and the cam ring 1
The small diameter hole 38 communicating with the inner surface 10a of the vane chamber 2
Immediately before 2 communicates with the discharge port 28 (its V groove 40), the vane 18 on the rear side in the rotation direction of the vane chamber 22 thereof.
Is provided at a position slightly open to the front side.

The operation of the vane pump having the above structure will be described. When the rotor 14 rotates, the vane 18 moves while slidingly contacting the inner surface of the cam ring 10 to move the cam 10a.
The volume of the vane chamber 22 increases or decreases according to the shape of the. During the process in which the volume of the vane chamber 22 increases, the vane chamber 22 communicates with the suction port 26 to suck the oil. Further, at the moment when the rotor 14 rotates and the vane chamber 22 is cut off from the suction port, the vane chamber 22 is not yet connected to the discharge port 28,
After that, until it communicates with the discharge port 28, the vane chamber 22
Is gradually compressed, and the pressure in the vane chamber 22 is increased to the maximum discharge pressure. Next, the vane chamber 22 communicates with the discharge port 28, and oil is discharged.

When the pressure inside the vane chamber 22 is higher than the discharge pressure in a region where the vane chamber 22 does not communicate with either the suction port 26 or the discharge port 28, the valve body 3
4 is pushed outward to reduce the pressure in the vane chamber 22 to a value approximately equal to the pressure in the discharge port 28. After all, the vane chamber 22 can be communicated with the discharge port 28 in a state where the pressure of the discharge port 28 and the pressure of the vane chamber 22 are substantially equal to each other, and the pulsation can be reduced and the generation of noise can be prevented.

At the moment when the vane chamber 22 next to the vane chamber 22 communicating with the discharge port 28 communicates with the small diameter hole 38, since the vane chamber 22 is in the suction stroke, the valve element 34 is moved to the discharge port 28. The flow of oil into the vane chamber 22 occurs due to bending under the influence of the pressure of
Due to the orifice effect of the small diameter hole 38, the valve characteristics, etc., there is no sudden change, and the shock wave is extremely small. Further, since this small shock wave is not transmitted to the power steering side and is directed to the tank side, noise etc. is generated. There is no danger of leading to.

FIG. 5 shows the valve portion of the second embodiment. In this embodiment, the valve element 34 is press-fitted into the circular hole 32 by giving a tightening margin and an annular backup member is provided on the outer side thereof. Since 42 is press-fitted to improve the sealing property, the same effect as that of the above embodiment can be obtained. In the case of a pressure balance type pump, two sets of suction ports and discharge ports are provided at symmetrical positions, and in this case, two valve bodies are also provided.

[0019]

As described above, according to the present invention, the pressure of the vane chamber is extremely close to the pressure of the discharge port due to the slight deformation of the valve element interposed between the vane chamber and the discharge port side. Since it can be communicated with the discharge port, it is possible to prevent the generation of a shock wave when the two communicate with each other.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of a vane pump according to an embodiment of the present invention.

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

FIG. 3 is a view on arrow A in FIG.

FIG. 4 is a view for explaining a communication cutoff state due to movement of the vane chamber.

FIG. 5 is a cross-sectional view of main parts of a second embodiment.

FIG. 6 is a simplified view showing a cross section of a conventional vane pump.

FIG. 7 is a graph showing changes in the volume of the vane chamber.

FIG. 8 is a graph showing a pulsation of discharge hydraulic pressure.

[Explanation of symbols]

 4 plate (rear body) 10 cam ring 10a cam 14 rotor 16 slit 18 vane 20 plate (side plate) 22 vane chamber 26 suction port 28 discharge port 34 valve disc 38 small hole (small diameter hole)

Claims (1)

[Claims] 1. A cam ring having a cam formed on its inner surface,
The rotor that rotates in the cam ring, the vanes that are inserted into the slits that are formed in the outer periphery of the rotor at equal intervals in the circumferential direction so as to be able to move back and forth, and the plates that sandwich the cam ring and the rotor from both sides are adjacent to each other. In the vane pump in which oil is sucked into the vane chamber from the suction port and discharged through the discharge port by increasing or decreasing the volume of the vane chamber formed between the two vanes, After the volume of the chamber reaches its maximum, a rotor rotation area is provided in which this vane chamber does not communicate with either of the above ports, and a cam shape that reduces the volume of the vane chamber within this area is created, and the vane chamber discharges. A valve element made of a deformable material is provided on the cam ring on the rear side in the rotation direction of the vane chamber at a position immediately before starting communication with the port, Vane pump of the outside of the valve body guiding the discharge pressure, and is characterized in that communication between the inside and the cam ring inner surface of the valve body by the small hole.