JPS6314078Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a variable displacement pump in which the discharge flow rate is varied by changing the amount of eccentricity of a cam ring with respect to the rotor.

<Prior art> In a conventional variable displacement vane pump of this type, an orifice is provided between the pump housing and the cam ring, and the eccentricity of the cam ring is changed by applying the longitudinal pressure of this orifice to the cam ring, thereby changing the rotational speed of the rotor. There is a system that controls the flow rate of pressure fluid supplied to fluid-operated equipment to a desired characteristic regardless of changes in the pressure fluid.

However, in such conventional variable displacement vane pumps, the orifice is formed between a cam ring that swings about a pivot pin and a limiting member attached to the inner circumference of the pump housing, so that the cam ring swings. There is a drawback that the opening area of the orifice changes due to variations in the position or the mounting position of the limiting member, making it difficult to set the characteristics.

<Purpose of the invention> The present invention was made in order to eliminate these drawbacks of the conventional technology.The purpose of this invention is to eliminate variations in the opening area of the orifice and to create a variable displacement type that allows easy setting of flow characteristics. To provide a vane pump.

<Structure of the invention> In order to achieve the above object, the present invention forms a control surface on the cam ring that faces the inner peripheral surface of the pump housing with a predetermined gap therebetween, and is parallel to the displacement direction of the cam ring. A control pin with a diameter equal to or smaller than the clearance is supported in the pump housing so that its outer periphery is in contact with the control surface and parallel to the rotor axis, and the small diameter portion formed on the control pin and the control surface are connected to each other. The feature is that an orifice is formed between the two.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. 1 and 2, reference numeral 10 indicates a pump housing. A hollow chamber 11 is formed in the pump housing 10, and a pair of side plates 1 are placed in the hollow chamber 11 with a fixing ring 12 in between.
9 and 20 are accommodated therein, and the open end of the hollow chamber 11 is closed with an end cover 13. Fixed ring 1
A cam ring 14 is housed within the cam ring 14 so as to be movable in the radial direction, and a crescent-shaped pressure fluid passage 15 is provided between the outer periphery of the cam ring 14 and the inner periphery of the fixed ring 12.
is formed. A rotor 17 that holds a number of vanes 16 so as to be slidable in the radial direction is rotatably housed in the cam ring 14 , and the rotor 17 is engaged with a spline at one end of a rotating shaft 18 that is rotatably supported on the pump housing 10 . are combined.

A suction port 21 that communicates with the suction area of the pump chamber and a discharge port 22 that communicates with the discharge area of the pump chamber are formed on each inner surface of the pair of side plates 19 and 20 that face each other with the cam ring 14 in between. . The suction port 21 communicates with the suction port 23 provided in the pump housing 10, and the discharge port 2
2 is communicated with the pressure fluid passage 15. A spring 25 is inserted between the end cover 13 and the side plate 20, and a pressure chamber 26 is formed, and this pressure chamber 26 communicates with a pump chamber corresponding to the discharge area.

A flat support surface 14a is formed at the lower end of the cam ring 14, and a plurality of guide pins 31 are connected to the axis of the rotor 17 between the support surface 14a and a seat plate 30 attached to the inner circumference of the fixed ring 12. are interposed in parallel. These guide pins 31
One of them passes through the side plate 19 and connects both ends to the pump housing 10 as shown in FIG.
The other guide pin 31 has a length approximately equal to the width of the cam ring 14 and is disposed on both side plates 19 and 20 to prevent the cam ring 14 from rotating. The cam ring 14 is pressed downward by the fluid pressure action of the pump chamber and is pressed against the guide pin 31, thereby connecting the lower part of the pressure fluid passage 15 to the guide pin 31.
At the same time, the cam ring 14 is guided so as to be linearly movable in the radial direction.

Further, as shown in FIGS. 3 and 4, the upper end of the cam ring 14 has a control surface 1 that faces the inner peripheral surface of the fixed ring 12 with a predetermined gap therebetween.
4b is formed parallel to the sliding direction of the cam ring 14, that is, parallel to the support surface 14a.
On the other hand, a control pin 32 having the same diameter as the clearance is supported in the pump housing 10 so that its outer circumference abuts the control surface 14b and is parallel to the axis of the rotor 17. The control pin 32 has a small diameter portion 32a at its center, and an orifice 40 is formed between the small diameter portion 32a, the control surface 14b, and the inner peripheral surface of the fixing ring 12. The orifice 40 divides the pressure fluid passage 15 into a first pressure chamber 15A communicating with the discharge port 22 and a second pressure chamber 15B communicating with the discharge port 33. A control protrusion 14c having a width and height slightly smaller than the width and step of the small diameter portion 32a is formed on the control surface 14b. The control protrusion 14c enters the orifice 40 as the cam ring 14 is displaced in the radial direction, thereby reducing its opening area.

A fixing ring 12 is attached to the pump housing 10.
A spring receiver 37 is fitted through the cam ring 14, and a ring pressing spring 38 is inserted between the spring receiver 37 and the cam ring 14. The repulsive force of the ring pressing spring 38 urges the cam ring 14 toward the first pressure acting chamber 15A (leftward in FIG. 2), and the cam ring 1 is brought to the maximum eccentric position where the normal stopper 39 abuts the fixed ring 12.
Holds 4.

Next, the operation of the above configuration will be explained. When not driven, the stopper 39 is held at the maximum eccentric position where it abuts the fixed ring 12, as shown in FIG. Then, the fluid sucked into the pump chamber through the suction port 23 and the suction port 21 is discharged as a pressure fluid into the first pressure action chamber 15A through the discharge port 22, and further flows into the second pressure action chamber 15B through the orifice 40 and discharged. The power is supplied from the outlet 33 to the power steering device.

When the rotational shaft 18 and the rotor 17 rise to a predetermined rotational speed and the amount of pressure fluid discharged to the first pressure action chamber 15A increases, a phenomenon occurs between the first pressure action chamber 15A and the second pressure action chamber 15B. Due to the differential pressure generated, the cam ring 14 is moved to the right in FIG. 2 against the ring pressing spring 38. As a result, the amount of eccentricity of the cam ring 14 with respect to the rotor 17 decreases as the differential pressure increases, in other words, as the pump rotation speed increases, reducing the discharge amount per pump rotation,
The amount of pressure fluid supplied to the power steering device is
As shown in the figure, control is performed to Q1 regardless of the pump rotation speed.

When the rotational speed of the rotor 17 further increases and the differential pressure between the first pressure action chamber 15A and the second pressure action chamber 15B increases, the cam ring 14 further moves to the right, and as a result, the control protrusion 15c moves toward the orifice 4.
0 and reduce its opening area. For this reason, the first pressure action chamber 15A and the second pressure action chamber 15
The differential pressure between B increases and the cam ring 14 is moved further to the right than before. As a result, the rotor 17
The amount of eccentricity of the cam ring 14 relative to the engine speed decreases, reducing the discharge amount per revolution of the pump, and reducing the amount of pressure fluid supplied to the power steering device to Q2.

In the above embodiment, the upper surface shape of the control protrusion 14c formed on the control surface 14b is formed flat, but the shape is not limited to this. For example, the upper surface is formed into a chevron shape as shown in FIG. When the control protrusion 14c is formed as shown in FIG. 7, the flow rate characteristic is such that the discharge flow rate gradually decreases as the rotational speed increases, and various characteristics can be obtained by selecting various shapes of the control protrusion 14c.

Furthermore, in the above embodiments, the cam ring 14
The cam ring 14 is made of a sintered alloy.
By sintering the control protrusion 14c integrally with the control protrusion 14c, the control protrusion 14c can be easily formed.

<Effects of the invention> As detailed above, the variable displacement vane pump of the present invention has a control surface on the cam ring that faces the inner peripheral surface of the pump housing with a predetermined gap in between and is parallel to the displacement direction of the cam ring. A control pin having a diameter equal to or smaller than this gap is supported on the pump housing so that its outer periphery is in contact with the control surface and parallel to the rotor axis, and a small diameter portion is formed in the control pin. A control protrusion having a width and height slightly smaller than the width and height of the small diameter part is formed protrudingly on the control surface, and is arranged between the control protrusion and the small diameter part to reduce the amount of eccentricity of the cam ring. Since the orifice is formed with a reduced opening area, there is no variation in the opening area of the orifice due to settings, and the flow rate drop characteristic can be obtained with a simple configuration of just forming a control protrusion on the control surface. .

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view of a variable displacement vane pump according to the present invention, FIG. 2 is a cross-sectional view taken along the - line in FIG.
The figure is an enlarged cross-sectional view of the main part showing the control pin mounting part.
Fig. 4 is a sectional view taken along the - line in Fig. 3, Fig. 5 is a graph showing the flow rate characteristics of a variable displacement vane pump, Fig. 6 is a sectional view of main parts showing another embodiment of the control pin attachment part, and Fig. 7 is a sectional view taken along the line - The figure is a graph showing the flow rate characteristics of a variable displacement vane pump in another embodiment. 10... Pump housing, 14... Cam ring, 14b... Control surface, 14c... Control protrusion, 1
5... Pressure fluid passage, 16... Vane, 17...
Rotor, 32...control pin, 32a...small diameter part,
40... Orifice.

Claims (1)

[Scope of utility model registration request] A cam ring is housed in a pump housing so as to be linearly displaceable in the radial direction, a rotor is rotatably housed within the cam ring, and a pump chamber partitioned by a plurality of vanes is formed between the rotor and the cam ring. In the variable displacement vane pump, an orifice is formed in the pressure fluid passage for sending pressure fluid to the outside from the pump chamber, and the pressure before and after the orifice is applied to the cam ring to displace the cam ring. A control surface facing the inner peripheral surface of the pump housing with a predetermined gap is formed parallel to the displacement direction of the cam ring, and a control pin having the same diameter or smaller diameter than this gap is connected so that its outer periphery is in contact with the control surface. The control pin is supported by the pump housing so as to abut and be parallel to the rotor axis, the control pin is formed with a small diameter part, and the control protrusion has a width and height slightly smaller than the width and height of the small diameter part. A variable displacement vane pump characterized in that an orifice is formed protrudingly on a control surface, and an orifice whose opening area decreases as the eccentricity of the cam ring decreases between the control protrusion and the small diameter portion.