JPH04194390A - Variable displacement vane pump - Google Patents

Abstract

PURPOSE:To reduce the extent of pump discharge pulsation by installing a fluid escape groove in which any shielding by a cam ring is solved at a rotor rotational area where the cam ring rocks at a maximum or minimum eccentric position. CONSTITUTION:When rotational speed in a rotor 1 is varied, pump discharge pressure varies according to it, and a cam ring 3 rockes into specific eccentric position. Therefore, each of fluid escape grooves 43, 44 installed in a rocking position at time of maximum or minimum eccentricity of the cam ring 3 on the wall of a housing 4 is exposed into a pump chamber P, and when a vane 2A is reached to these fluid escape grooves 43, 44, a part of compressed fluid is discharged to a low pressure side pump chamber P2 from a high pressure side pump chamber P1, thus any pressure increase in the fluid being discharged to a discharge port 42 is checked. With this constitution, a discharge pressure peak of a pump is solvable and, what is more, pulsation is reducible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable displacement vane pump, and particularly to a pump structure that can significantly reduce pump discharge pulsation.

[Prior Art] FIG. 6 shows a cross section of a pump portion of a variable displacement heavy-duty vane pump. In FIG. 6, a circular rotor 1 that is fixed to a rotating shaft 11 and rotates has nine grooves extending in the radial direction at equal intervals on the outer circumference, and a plate vane 2 is slidably provided in each groove. It is inserted and urged outwardly by fluid pressure.

A circular ring-shaped force ring 3 is disposed on the outside surrounding the rotor 2, and one side of the cam ring 3 abuts against the inner wall of the housing 4 via a shaft member 31, and the other side It abuts against the inner wall of the housing 4 via the seal member 32, and is able to swing up and down about the shaft member 31 as a fulcrum. A portion of the other side of the cam ring 3 protrudes into the recess of the pump housing 4 and serves as a spring receiver 33.
A coil spring 34 is disposed between the spring receiver 33 and the lower surface of the recess.

The tip of each of the protruding vanes 2 contacts the circular inner periphery of the cam ring 3 to form a pump chamber P between the adjacent vane 72, and these pump chambers P are formed on both side end surfaces of each vane 2 and the cam ring 3. It is closed by the housing 4 wall which abuts the housing.

In the space S between the upper half of the cam ring 3 extending from the shaft member 31 to the seal member 32 and the inner wall of the pump housing 4, the pressure of the discharged fluid is applied to the flash circuit inside the pump housing 4 via a control valve (flash circuit). On the other hand, the pressure in the space between the lower half of the cam ring 3 and the wall of the pump housing 4 is a turning pressure.

Therefore, in a region where the rotor rotational speed is low, the pressure in the space S is small due to the flash valve, and the cam ring 3 swings upward due to the spring force of the coil spring 34, forming a gap between the cam ring 3 and the eccentric cam ring 3. Each of the pump chambers P rotates and moves while its volume changes greatly (arrows in the figure). Fluid is sucked through a suction port 41 formed on the housing 4 wall facing the pump chamber P whose volume gradually increases, and a discharge port 41 formed on the housing 4 wall facing the pump chamber P whose volume gradually decreases. Fluid is pumped and discharged to port 42 .

As the rotor rotation speed increases, the pressure in the space S is controlled to increase, and the cam ring 3 swings downward against the spring force of the coil spring 34, so that the amount of eccentricity between the rotor 1 and the cam ring 3 decreases. . As a result, the change in volume of each pump chamber P due to rotational movement is reduced, the discharge flow rate per rotor rotation is reduced, and the supply pressure is controlled to be constant.

[Problems to be Solved by the Invention] In the vane pump having the above structure, the pressure of the fluid discharged from the discharge boat 42 pulsates greatly each time it passes through each pump chamber P whose volume gradually decreases as it moves.
This is shown in FIG. 4 (1).

This figure is for the pump in the low speed rotation range (>500 rpm).
Pressure fluctuations are periodically repeated every 40 degrees, which is the installation interval of the vanes 2. This pressure fluctuation does not change even if the pump rotation becomes high speed (4000 rpm>), but as shown in FIG. 5(1), the rotation angle position indicating the maximum pressure shifts.

(In the figure, the difference is about 10 to 15 degrees.) An object of the present invention is to provide a variable displacement vane pump that can effectively reduce such pump discharge pulsation with a simple structure.

[Means for Solving the Problems] To explain the present invention in detail, vanes 2 are provided at equal intervals around the outer circumference of a rotating circular rotor 1 (FIG. 1), and these:
The tip of the vane 2 is brought into contact with the circular inner periphery of a cam ring 3 disposed outside around the rotor 1, and the inner space of the cam ring 3 is divided into a plurality of pump chambers P by the vane 2, and each of the vanes A suction port 41 and a discharge boat 42 are provided on the wall of the housing 4 that contacts the side end surfaces of the cam ring 2 and the cam ring 3 to close each pump chamber P, and fluid is sequentially sucked into each pump chamber P from the suction port 41, and each The vane pump sequentially compresses and discharges fluid from the pump chamber P to the discharge boat 42, and is configured to swing the cam ring 3 to a predetermined eccentric position with respect to the rotor 1 in accordance with the pump discharge pressure applied to a half circumference of the outer peripheral surface of the cam ring 3. In a variable displacement vane pump that adjusts the pump discharge amount by adjusting the pump discharge amount, the wall of the housing 4 has rotor rotational angle positions at which the pump discharge pressure is maximum at the eccentric positions of the cam ring 3 at maximum eccentricity and minimum eccentricity, respectively. When the cam ring 3 is at its maximum eccentricity or at its minimum eccentricity, it is released from the shielding by the side end surface of the cam ring and exposed into the pump chamber P, allowing a portion of the fluid in the high-pressure side pump chamber P1 to pass through the vane 2 to the adjacent pump chamber P. Fluid escape grooves 43 and 44 are formed to allow fluid to escape to the low pressure side pump chamber P2.

[Operation] In the vane pump configured as described above, when the rotational speed of the rotor 1 changes, the pump discharge pressure changes accordingly, and the cam ring 3 swings to a predetermined eccentric position. This results in
Fluid relief levers 43 and 44 are provided at the rocking position of the cam ring 3 on the housing 4 wall when the cam ring 3 is at maximum eccentricity or at the minimum eccentricity.
is exposed into the pump chamber P, and when the vane 2A reaches the fluid relief side 43, 44, a part of the compressed fluid is discharged from the high pressure side pump chamber P1 to the low pressure side pump chamber P2, and is discharged to the discharge port 42. Increase in pressure of the fluid being forced is suppressed.

Therefore, the positions of the fluid relief arms 43 and 44 are arranged to correspond to the rotor rotation angle position where the pump discharge pressure peaks in the rotor rotation range in which the cam ring 3 is swung to the maximum or minimum eccentric position. , pump discharge pressure peaks are eliminated and pulsation is reduced.

[Example] An example of the present invention will be described below, focusing on the differences from the conventional one.

In FIG. 1, a groove extending in the circumferential direction is formed in the upper part of the wall of the housing 4 in contact with the side end surface of the cam ring 3 and each vane 2 at a position where the vane 2A has rotated about 25 degrees beyond the 0 degree point. This is a fluid relief groove 43. The fluid relief channel 43 has a non-rectangular cross section (FIG. 2) and is longer than the thickness of the vane 2. In the illustrated state in the rotor low speed rotation range, approximately half of the fluid relief groove 43 is released from being shielded by the side end surface of the cam ring 3 that has swung upward, and the leading high-pressure pump chamber P1 and the following low-pressure pump It communicates with room P2.

On the other hand, at the lower part of the wall of the housing 4, a fluid relief bank 44 having the same shape as the fluid relief bank 43 is formed at a position where the vane 2A has rotated approximately 15 degrees beyond the 0 degree point, and this is formed upward. It is completely closed by the side end surface of the swung cam ring 3.

Therefore, each time the vane 2 passes the fluid relief bank 43,
Compressed fluid is discharged from the pump chamber P1 communicating with the discharge port 42 to the subsequent pump chamber P2, thereby suppressing an increase in the discharge pressure. This is shown in Fig. 4 (2), and as can be seen from the figure, the pressure peak that conventionally existed near the rotor rotation angle of 25 degrees has been eliminated (of course, the same thing has occurred before 40 degrees). Overall, the pulsations in the discharge pressure are small.

When the rotor rotational speed increases, the cam ring 3 swings downward as shown in FIG. 3 as the discharge pressure increases, and the fluid relief pipe 43 is completely closed by the side end surface of the cam ring 3.
Instead, the fluid escape groove 44 is released from the shield and exposed.

Therefore, each time the vane 2 passes through the fluid relief groove 44, compressed fluid is discharged from the subsequent high-pressure pump chamber P1 leading to the discharge port 42 to the low-pressure pump chamber P2, thereby suppressing an increase in the discharge pressure. It will be done. This is shown in FIG. 5(2), and the pressure peak that conventionally existed near the rotor rotation angle of 15 degrees (the rotation angle of the vane 2A) is eliminated, and the pulsation of the discharge pressure is suppressed to a small level as a whole. In addition, since the fluid relief pipe 43 is closed, the compressed fluid is not discharged near the rotor rotation angle of 25 degrees, where the pressure does not reach a peak in the high-speed rotation state, and pulsation due to a drop in discharge pressure due to this is prevented.

Thus, according to this embodiment, discharge pulsation can be reduced and noise generation etc. can be effectively prevented in both low speed and high speed rotor rotation states. In addition, in the above embodiment, there are one fluid relief groove in the upper and lower part of the housing 4 wall.
Although they are provided at different locations, they may be provided at several locations above and below depending on the peak of pulsation.

[Effects of the Invention] As described above, the variable displacement vane pump of the present invention has a simple configuration due to the fluid relief groove that eliminates shielding by the cam ring in the rotor rotation range where the cam ring swings to the maximum or minimum eccentric position. This reduces pump discharge pulsation and enables quiet pump operation.

[Brief explanation of the drawing]

1 to 3 show one embodiment of the present invention, FIG. 1 is a sectional view of the pump section, FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1, and FIG. 3 is a sectional view of the pump section. Figures 4 and 5 are diagrams comparing temporal changes in pump discharge pressure with conventional examples, respectively.
FIG. 6 is a sectional view of a □ pump section showing a conventional example. 1...Rotor 2.2A...Vane 3...Cam ring 4...Pump housing 41...Suction boat 42...Discharge boat 43.44...Fluid relief system P, PL, P2 ...Pump room Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] Vanes are provided at equal intervals around the outer circumference of a rotating circular rotor,
The tips of these vanes are brought into contact with the circular inner periphery of a cam ring disposed outside around the rotor, and the inner space of the cam ring is divided into a plurality of pump chambers by the vanes, and the side end surfaces of each vane and cam ring are A suction port and a discharge port are provided on the housing wall that closes each pump chamber in contact with the housing wall, and fluid is sequentially sucked into each pump chamber from the suction port, and fluid is sequentially compressed and discharged from each pump chamber to the discharge port. In the vane pump, the variable displacement vane pump adjusts the pump discharge amount by swinging the cam ring to a predetermined eccentric position with respect to the rotor in accordance with the pump discharge pressure applied to a half circumference of the outer circumferential surface of the cam ring. The wall has a rotor rotation angle position where the pump discharge pressure is maximum at the swing position of the cam ring at the maximum eccentricity and the minimum eccentricity, respectively, and by the side end surface of the cam ring at the maximum eccentricity or the minimum eccentricity of the cam ring. A variable capacity type characterized by forming a pair of fluid relief grooves that are released from the shield and exposed into the pump chamber and allow part of the fluid in the high pressure side pump chamber to escape to the adjacent low pressure side pump chamber via a vane. vane pump.