JP2000120560A - Vane pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce vibration and noise in a vane pump. SOLUTION: When a plane equally dividing a pressure transition segment positioned between an intake port 41 and a discharge port 42 is defined as a casing transition segment divisional plane Sc, a vane pump is equipped with a variable precompression amount mechanism which increases a precompression amount of a pump chamber by moving a cam ring 70 in a direction roughly vertical to the casing transition segment divisional plane Sc accompanying a rising of a pump discharge pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a vane pump used for, for example, a power steering device of a vehicle.

[0002]

2. Description of the Related Art Conventionally, a vane pump of this type supports a cam ring surrounding each vane rotatably via a support pin, as disclosed in, for example, Japanese Patent Application Laid-Open No. H8-200399. In some cases, the pump discharge flow rate is adjusted by changing the amount of eccentricity of the cam ring with respect to the pressure.

[0003]

However, in such a conventional vane pump, the pump chamber moves from the suction stroke to the discharge stroke with the rotation of the rotor when the pump discharge pressure is high. There is a possibility that the pre-compression amount for compressing the chamber is insufficient, and the vibration and noise of the vane pump increase. In addition, when the pump discharge pressure is high,
There is a possibility that the pre-compression amount in which the pump chamber is compressed in the pre-decompression stroke in which the pump chamber shifts from the discharge stroke to the suction stroke with the rotation of the rotor is insufficient, and the vibration and noise of the vane pump may increase.

In order to prevent this, there is a method in which the center of the cam ring is shifted to the suction port side in advance to secure the amount of pre-compression and the amount of pre-pressure reduction. There is a problem that the amount of compression and the amount of pre-decompression become excessive, and the vibration and noise of the vane pump increase.

The present invention has been made in view of the above problems, and has as its object to reduce vibration and noise in a vane pump.

[0006]

According to a first aspect of the present invention, a plurality of vanes slidably protruding from a rotating rotor, a cam ring which slidably contacts an outer peripheral end of each vane to define a pump chamber, In a vane pump including a suction port for flowing a working fluid into a pump chamber that expands with rotation of a rotor and a discharge port for flowing a working fluid from a pump chamber that contracts with rotation of the rotor, a vane pump including a suction port and a discharge port Is defined as a casing transition section dividing plane Sp, the cam ring is moved in a direction substantially perpendicular to the casing transition section dividing plane Sp as the pump discharge pressure increases. A variable pre-compression amount mechanism for increasing the pre-compression amount of the chamber is provided.

According to a second aspect of the present invention, in the first aspect, the variable precompression amount mechanism includes an adapter ring for slidably supporting the cam ring in a direction substantially perpendicular to the casing transition section dividing surface Sp, and a precompression of the pump chamber. A cam ring pressure chamber that expands as the cam ring is displaced in the direction in which the amount increases is provided, and a discharge pressure introduction passage that guides a pump discharge pressure to the cam ring pressure chamber.

According to a third aspect of the present invention, in the second aspect, a variable displacement mechanism for changing the displacement of the pump by rotating the adapter ring is provided.

[0009]

According to the first aspect of the present invention, the pre-compression amount and the pre-decompression amount of the pump chamber increase as the pump discharge pressure increases, so that the pressure in the pump chamber is smooth even if the cam ring moves. Is maintained, and the vibration and noise of the vane pump can be reduced.

In the second aspect of the invention, the cam ring is formed on the casing transition section dividing surface S as the pump discharge pressure increases.
By displacing in the direction substantially perpendicular to p and increasing the amount of pre-compression and pre-decompression of the pump chamber, a state in which the pressure in the pump chamber smoothly changes even when the cam ring moves, is maintained,
The vibration and noise of the vane pump can be reduced.

In the third aspect of the present invention, the displacement of the pump is changed by rotating the adapter ring.
The flow rate of hydraulic oil returned from the vane pump to the tank is reduced to reduce wasteful energy consumption.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a vane pump provided as a hydraulic pressure source of a power steering device mounted on a vehicle will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the vane pump 1 includes a rotor 50 rotatably housed in a casing 60, a plurality of vanes 24 slidably projecting from the rotor 50,
The cam ring 70 surrounding each vane 24 is mainly constituted.

Rotation from the engine is transmitted to the rotor 50 via a drive shaft (not shown), a pulley, a belt, and the like.
Rotate counterclockwise as indicated by the arrow in the figure. Each of the vanes 24 slides its outer peripheral end against the inner peripheral surface of the cam ring 70 while moving in and out of the rotating rotor 50 in the radial direction to expand and contract the pump chamber. Hydraulic oil is sucked from the suction port 41 into the pump chamber that expands between the vanes 24 as the rotor 50 rotates, and hydraulic oil is discharged to the discharge port 42 from the pump chamber that contracts between the vanes 24. The suction port 41 communicates with the tank via a suction passage (not shown), and the discharge port 42 communicates with a hydraulic cylinder of a power steering device (not shown) via the pump discharge passage 11. A variable orifice 80 is provided in the middle of the pump discharge passage 11.

The inner peripheral surface of the cam ring 70 has a substantially circular cross section, and the cam ring center Oc with respect to the rotor axis Op.
The larger the amount of eccentricity L is, the larger the displacement of the pump is, and the larger the pump discharge flow rate is. When the cam ring center Oc is on the rotor axis Op, the pump discharge flow rate becomes zero.

An adapter ring 90 for accommodating the cam ring 70 as a variable displacement mechanism for changing the pump discharge flow rate.
The adapter ring 90 is rotatably supported by the casing 60 via a support pin 91. As the adapter ring 90 rotates counterclockwise in the figure and the eccentric amount of the cam ring center Oc with respect to the rotor shaft core Op increases, the pump displacement increases and the pump discharge flow rate increases.

Here, the suction port 41 and the discharge port 42
Are equally divided, a plane including the rotor axis Op is defined as a casing transition section division plane Sp, and the space in the cam ring 70 is equally divided to be parallel to the casing transition section division plane Sp. The plane is defined as a cam ring transition section division plane Sc.

Each of the slide surfaces 91 and 61 is formed in a plane parallel to the casing transition section dividing plane Sp and the cam ring transition section dividing plane Sc so that the adapter ring 90 moves in a direction parallel to the casing transition section dividing plane Sp. It has become.

A spring 26 for urging the adapter ring 90 to the left in the drawing is provided. With the adapter ring 90 moved to the leftmost position by the urging force of the spring 26, the pump discharge flow rate becomes maximum.

In order to drive the adapter ring 90 against the spring 26, a first housing pressure chamber 7 and a second housing pressure chamber 8 are defined in the casing 60 so as to sandwich the adapter ring 90. The casing 60 is provided with a seal member 22 slidably in contact with the outer periphery of the adapter ring 90 to seal the first housing pressure chamber 7 and the second housing pressure chamber 8 respectively.

The first housing pressure chamber 7 is connected to a pump discharge passage 11 upstream of the variable orifice 80 through a passage 12.
On the other hand, the second housing pressure chamber 8 communicates with the pump discharge passage 11 downstream of the variable orifice 80 via the passage 13. As a result, the pump discharge flow rate increases and the differential pressure across the variable orifice 80 increases, so that the adapter ring 90 turns clockwise in the figure against the spring 26 so that the pump discharge flow rate decreases. It has become.

The pump chamber defined between the vanes 24 expands in a region above the cam ring transition section dividing plane Sc in the figure and sucks the hydraulic oil from the suction port 41, and is drawn from the cam ring transition section dividing plane Sc in the figure. The hydraulic fluid contracts in the lower region and discharges the hydraulic oil to the discharge port 42, but there is a pre-compression stroke in which the pump chamber is compressed in a process in which the pump chamber shifts from the suction stroke to the discharge stroke with the rotation of the rotor 50, The amount of pre-compression of the pump chamber increases as the cam ring transition section division surface Sc moves toward the suction port 41 (upward). Further, there is a pre-decompression step in which the pump chamber is depressurized in the process of shifting from the discharge stroke to the suction stroke with the rotation of the rotor 50, and the pre-decompression amount of the pump chamber is determined by the cam ring transition section dividing surface Sc being the suction port. It increases as it moves to the 41 side.

As a variable pre-compression amount mechanism for changing the pre-compression amount of the pump chamber, a cam ring 70 includes an adapter ring 90.
Are supported so as to be movable in a direction perpendicular to the cam ring transition section division plane Sc and the casing transition section division plane Sp.

A spring 27 for urging the cam ring 70 downward in the figure is provided. With the cam ring 70 moved to the lowest position by the urging force of the spring 27, the amount of pre-compression of the pump chamber is minimized.

To drive the cam ring 70 against the spring 27, the cam ring 70 is attached to the adapter ring 90.
The first cam pressure chamber 17 and the second cam pressure chamber 18
Is defined. The adapter ring 90 has a cam ring 70
A pair of seal members 29 that are in sliding contact with the outer peripheral side of
The space between the first cam pressure chamber 17 and the second cam pressure chamber 18 is sealed.

The first cam pressure chamber 17 is connected to the discharge pressure introduction passage 14.
And the second cam pressure chamber 8 communicates with the suction port 41 through the passage 15. As a result, as the pump discharge pressure increases, the cam ring 70 moves upward in the drawing against the spring 27, and the pre-compression amount and the pre-reduction amount of the pump chamber increase. Although the dimensional differences between the illustrated parts are exaggerated and larger than the actual ones for convenience, the distance that the cam ring 70 actually moves in the vertical direction is about 1% of the cam diameter.

Next, the operation of the embodiment of the present invention configured as described above will be described.

While the vane pump 1 is stopped and the pump rotation speed rises to a predetermined value, the adapter ring 90 is positioned on the left side by the urging force of the spring 26, and the eccentricity L of the cam ring center Oc with respect to the rotor shaft Op is maximized. And the amount of hydraulic oil flowing through the pump discharge passage 11 increases as the rotation speed of the rotor 50 increases. Thus, the pump discharge pressure is sufficiently increased from the time of low-speed running of the vehicle, and the hydraulic assist force required for the power steering device can be secured.

When the differential pressure across the variable orifice 80 rises above a predetermined value in an operating region where the pump rotation speed rises above a predetermined value, the adapter ring 90 turns clockwise against the urging force of the spring 26. , The displacement of the pump is reduced. By automatically adjusting the position of the adapter ring 90 and controlling the pump discharge amount, the flow rate of hydraulic oil returned from the vane pump 1 to the tank is reduced, thereby reducing unnecessary energy consumption.

By the way, in the pre-compression stroke in which the pump chamber shifts from the suction stroke to the discharge stroke, if the pressure in the pump chamber does not rise smoothly, vibration and noise increase. Further, in the pre-decompression stroke in which the pump chamber shifts from the discharge stroke to the suction stroke, if the pressure in the pump chamber does not drop smoothly, vibration and noise increase. In response to this, the conventional vane pump shifts the timing at which the pump chamber communicates with the discharge port, or shifts the cam ring transition section division plane from the casing transition section division plane (rotor shaft core) to the suction port side.
The pre-compression amount and the pre-decompression amount were increased. However, as the pump discharge pressure increases, the appropriate pre-compression amount and pre-decompression amount also increase, so that the pre-compression amount and the pre-decompression amount become too large or insufficient according to the pump discharge pressure, and vibration and Noise increases.

In response to this, the present invention moves the cam ring 70 toward the suction port 41 as the pump discharge pressure increases, and increases the amount of pre-compression and pre-decompression of the pump chamber. In the pre-compression stroke in which the apparent change in the flow rate becomes large and the pump chamber shifts from the suction stroke to the discharge stroke, the pressure rises smoothly, and the pre-compression in which the pump chamber shifts from the discharge stroke to the suction stroke is maintained. The operation state in which the pressure smoothly drops during the stroke is maintained, and the vibration and noise of the vane pump 1 can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a vane pump according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 vane pump 7 first housing pressure chamber 8 second housing pressure chamber 11 pump discharge passage 14 discharge pressure introduction passage 24 vane 50 rotor 60 casing 70 cam ring 80 spool 90 adapter ring Oc cam ring center Op rotor shaft core Sc cam ring transition section split surface Sp Casing transition section division surface

 ────────────────────────────────────────────────── ─── Continuing the front page (72) Inventor Jun Inoue 2-4-1 Hamamatsucho, Minato-ku, Tokyo World Trade Center Building Kayaba Industry Co., Ltd. F-term (reference) 3H040 AA03 BB01 BB11 CC10 CC22 DD23 DD33 DD35 3H044 AA02 BB05 CC11 CC21 DD10 DD13 DD21 DD35

Claims (3)

[Claims] A plurality of vanes slidably projecting from a rotating rotor; a cam ring defining a pump chamber by sliding an outer peripheral end of each of the vanes; and a cam ring extending with rotation of the rotor. A vane pump comprising: a suction port for allowing a working fluid to flow into a pump chamber; and a discharge port for allowing a working fluid to flow from the pump chamber, which contracts with rotation of the rotor, wherein the vane pump has a position between the suction port and the discharge port. When the plane that equally divides the pressure transition section to be divided is defined as a casing transition section division plane Sp, the cam ring is moved in a direction substantially perpendicular to the casing transition section division plane Sp as the pump discharge pressure increases. The vane pump according to claim 1, further comprising a variable precompression amount mechanism for increasing the precompression amount of the chamber. 2. The variable precompression mechanism includes an adapter ring that slidably supports the cam ring in a direction substantially perpendicular to the casing transition section dividing surface Sp, and a direction in which the precompression amount of the pump chamber increases. The vane pump according to claim 1, further comprising: a cam ring pressure chamber that expands as the cam ring is displaced; and a discharge pressure introduction passage that guides a pump discharge pressure to the cam ring pressure chamber. 3. The vane pump according to claim 2, further comprising a variable displacement mechanism that changes the displacement of the pump by rotating the adapter ring.