JPH09317660A - Vane pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase cell internal pressure smoothly toward the internal pressure of a suction port even though the internal pressure of the suction port is high, by arranging a pressure difference loosening groove into a plurality of stages from the suction port position in the inner surface of a container by which a pump chamber is sectioned toward an intake port side. SOLUTION: In the case that a cell C1 is passed through a pressure difference loosening groove 4B while being communicated with an intake port 12, pressure difference is loosened between a suction port 2 and the intake port 12. After the cell C1 is disconnected from the intake port 12, and also communicated with the end 4B1 of the uppermost stream side of the pressure difference loosening groove 4B on the uppermost stream side, pressure in the suction port 2 is introduced to the inside of the cell C1, and the pressure of the cell C1 is started to be increased. Pressure difference loosening action can be obtained by partially lowering seal action between a vane 22-1 and a side plate by the pressure difference loosening groove 4B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a so-called vane pump, and more particularly to an improved vane pump that smoothly increases pressure from suction pressure to discharge pressure.

[0002]

2. Description of the Related Art FIG. 5 shows an outline of a vane pump here. The vane pump referred to in this specification refers to one in which a rotor having a plurality of vanes rotates in a container defining a pump chamber to obtain a pumping action. That is, as illustrated in FIG. 5, a pump container is formed by the side plate 106, the substantially ring-shaped cam ring 108, and another side plate (not shown), and the inner surface of the container defines a substantially cylindrical pump chamber 126. To be done. The pump room 126
The rotor 120 is housed in the rotor 120.
Is rotated by the rotating shaft 124. A plurality of vanes 122 are radially attached to the rotor 120, and the vanes 122 are urged outward, that is, toward the inner peripheral surface 110 side of the cam ring 108. The inner peripheral surface 110 of the cam ring 108 has a substantially elliptical shape having a short diameter portion and a long diameter portion, and as a result, one vane is defined by the inner peripheral surface 110 of the cam ring 108 and the outer peripheral surface of the rotor 120. The volume of the pump chamber (hereinafter referred to as cell C) is the rotor 12
It changes with the rotation of 0. In the case shown, the rotor 1
20 rotates counterclockwise, suction ports 112 and 118 are provided at positions where the inner peripheral surface 110 changes from the short diameter portion to the long diameter portion, and discharge ports 102 and 114 at the positions where the inner diameter surface 110 changes from the long diameter portion to the short diameter portion. Is provided. Normal discharge port 10
2, 114 and suction ports 112, 118 are formed in the side plate 106.

With this structure, the suction port 112, while the volume of one pump chamber (cell C) expands,
A fluid is sucked into the cell C through the suction ports 112 and 118 in communication with 118. The fluid sucked into the cell C is pressurized while the volume of the cell C contracts, and communicates with the discharge ports 102 and 114 in a pressurized state. Discharge port 1
02 and 114 are used, for example, as pressure oil supply ports of the power steering system, and discharge ports 102 and 1
The pressure inside 14 is high.

If the cell C suddenly communicates with the discharge ports 102 and 114 while the position of the cell C moves along with the rotation of the rotor 120, a sudden pressure change occurs at the moment when the cell C and the discharge port communicate with each other. Due to this abrupt pressure change, the rotor and vanes may vibrate and cause noise. In order to prevent such a sudden pressure change, pressure difference relaxing grooves 104 and 116 are provided on the inner surface of the container from the discharge port position toward the suction port side. This pressure difference relief groove 1
When 04 and 116 are provided, one cell C approaches the discharge ports 102 and 114, and the preceding vane starts to approach the pressure difference relaxation grooves 104 and 116, and is still in communication with the discharge port during pressurization. No cell C
And the pressure difference between the cell C and the cell C that is already in communication with the discharge port before the pressure difference are reduced through the pressure difference relaxation grooves 104 and 116, and the pressure in the cell C and the pressure in the discharge port are reduced. The cell C communicates with the discharge port in the state where the pressure difference is relaxed. Therefore, the abrupt change of the pressure described above is prevented.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The length, width, depth and the like of 116 are designed so that the above-mentioned pressure difference alleviating action can be appropriately obtained. In this case, the dimension parameter of the pressure difference relaxing groove can be appropriately determined under the condition that the pressure in the discharge ports 102 and 114 is maintained at the predetermined pressure.

However, when this vane pump is used in a power steering system, for example, the pressure in the discharge port fluctuates. This is because the pressure in the discharge port changes when the steering wheel is steered and when the steering wheel is not operated. When the pressure in the discharge port is higher than the predetermined pressure assumed at the time of design, the high pressure is rapidly introduced into the cell C which is not yet in communication with the discharge port through the pressure difference relaxing grooves 104 and 116.

FIGS. 6 and 7 are views for explaining this phenomenon in detail, and FIG. 6 (1) shows the preceding vane 122.
-1 and the following vane 122-2, one cell C1 defined by the inner peripheral surface 110 of the cam ring and the outer peripheral surface of the rotor 120 is still in communication with the suction port 112, and (2)
Shows that the cell C1 is blocked from the suction port 112 and the preceding vane 122-1 starts to hit the pressure difference relaxation groove 104, and (3) shows the preceding vane 122-1.
Shows immediately after passing through the suction port side end 104A of the pressure difference relaxing groove 104. After the state of (3), since the cell C1 communicates with the discharge port 102 via the pressure difference relaxation groove 104, the high pressure in the discharge port 102 begins to be introduced into the cell C1, and the pressure in the cell C1 rises. Get started. FIG. 7 shows how the pressure in the cell C1 changes with time ((3) and (5) on the time axis in the figure are (3) and (3) in FIG. 6).
It shows that the pressure in the cell C1 starts to rise promptly after the positional relationship of (3) in FIG. 6 is obtained (corresponding to the positional relationship of (5)). 6 (4) shows the positional relationship immediately before the cell C1 communicates with the discharge port 102, and the difference between the pressure in the cell C1 and the pressure in the discharge port 102 is sufficiently relaxed by the pressure difference relaxing groove 104. ing. (5) of FIG.
Indicates immediately after the cell C1 communicates with the discharge port 102, and thereafter, the pressure in the cell C1 becomes equal to the pressure in the discharge port 102 (pressure P2 in FIG. 7).

The broken line in FIG. 7 shows how the pressure changes when the pressure in the discharge port 102 is at the predetermined pressure P1 assumed when designing the dimensional parameters (length, width, depth) of the pressure difference relaxing groove 104. And the pressure in the cell is suction pressure P
The pressure is smoothly increased from 0 toward the discharge pressure P1.

The solid line in FIG. 7 is a graph observed by the present inventor, in which the pressure inside the discharge port 102 is a predetermined pressure P.
The change of the pressure in the cell C1 which occurs when the pressure is higher than 1 is shown. In this case, after reaching the positional relationship shown in (3) of FIG. 6, the discharge port 10 is inserted through the pressure difference relaxing groove 104.
The high pressure P2 in 2 is drastically introduced into the cell C1, and the pressure in the cell C1 fluctuates greatly. That is, the pressure difference relaxing groove 104 is too large in comparison with the pressure difference to be relaxed, and the pressure difference cannot be relaxed.
In this case, the pressure difference is alleviated by taking only the time for the cell C1 to communicate with the discharge port 102, but a sudden pressure change occurs at a timing preceding it. The present invention is to realize a vane pump capable of satisfactorily reducing the pressure difference even when the discharge pressure fluctuates as P1 and P2.

[0010]

According to the present invention, in a vane pump in which a rotor having a plurality of vanes rotates in a pump chamber defining container having a discharge port and a suction port, the discharge port on the inner surface of the container defining the pump chamber. The pressure difference relaxing groove is provided in a plurality of steps from the position toward the suction port side. The position from the discharge port position toward the suction port side here means the position where the preceding vane is located immediately before one cell communicates with the discharge port, and the pressure difference relaxing groove directly reaches the discharge port. You don't have to. For example, the discharge port may be formed on one side plate and the pressure difference relaxing groove may be formed on the other side plate. If necessary, both or one of the discharge port and the pressure difference reducing groove may be provided on the inner peripheral surface of the cam ring.

According to this structure, the preceding vane passes through the pressure difference reducing groove a plurality of times before one cell communicates with the discharge port, and the pressure difference reducing action is divided into a plurality of times. Is executed. For this reason, the pressure in the cell is smoothly increased toward the discharge pressure without abruptly changing, regardless of whether the pressure in the discharge port is high or low.

[0012]

[Preferable means] Further, at this time, the circumferential length of each pressure difference relaxing groove provided in a plurality of steps is set to be equal to or less than the thickness of the vane
Moreover, it is preferable that the circumferential length between the grooves (that is, the circumferential length of the seal portion) is equal to or less than the thickness of the vane. In this way, each pressure difference relaxation groove provides a small pressure difference relaxation effect, and by repeating this multiple times, the cell internal pressure is smoothly increased from the suction pressure to the discharge pressure.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION First, referring to FIGS. 1 and 2, the overall structure of a vane pump embodying the present invention will be described. The vane pump has an outer shape defined by a front housing 34 and a rear plate 50. The front housing 34 has a large-diameter recess 28 having a bottom 30 and the recess 2 thereof.
8, a through hole 38 coaxial with the suction passage 46, a suction passage 46, a discharge passage not shown, and a fluid passage not shown. The rear plate 50 covers the front housing 34 so as to close the recess 28.
Attached to. The side plate 6 is housed so as to be in contact with the bottom surface 30 of the recess 28.
The cam ring 8 is housed between the rear plate 50 and the rear plate 50. The outer periphery of the cam ring 8 is in surface contact with the inner periphery of the recess 28 and is fixedly positioned. As shown in FIG. 2, the inner peripheral surface 10 of the cam ring 8 has a substantially elliptical shape having a long diameter portion and a short diameter portion. The substantially elliptical inner peripheral surface 10, the right end surface of the side plate 6, and the left end surface of the rear plate 50 define a pump chamber 26 having a substantially columnar shape (correctly, a substantially elliptical cross section). Through the bearings 40 and 36, the rotary shaft 2 is inserted into the center through hole 38 of the front housing 34.
4 is rotatably supported. The rotating shaft 24 is rotated by an external force. The right end of the rotary shaft 24 in the drawing penetrates the pump chamber 26 and reaches the rear plate 50. Illustration 54
Is a bearing.

The rotor 20 is housed in the pump chamber 26 so as to be rotated by the rotating shaft 24. The rotor 20 and the rotary shaft 24 are locked by a key and a groove (not shown). The outer peripheral surface of the rotor 20 has a cylindrical shape,
A plurality of slits extending in the axial direction at equal intervals in the circumferential direction are radially formed therein. Vane 22 on each slit
Is housed so that it can move forward and backward in the radial direction. A discharge pressure, which will be described later, is introduced to the radially inner surface 22A of the vane 22, and urges the vane 22 outward, that is, toward the inner peripheral surface 10 of the cam ring 8. With this structure, one cell C is formed by the two vanes 22, the outer peripheral surface of the rotor 20, and the inner peripheral surface 10 of the cam ring 8, and a plurality of the cells C are formed side by side in the circumferential direction. The position of each cell C fluctuates as the rotor 20 rotates, and during one round, the positions of the cells C sequentially change in the order of the major diameter portion → the minor diameter portion → the major diameter portion → the minor diameter portion of the inner peripheral surface 10 of the cam ring 8. That is, the volume of each cell C changes from large to small to large to small while the rotor 20 makes one revolution. In FIG. 2, the rotor 20 rotates counterclockwise.

The side plate 6 is formed with two suction ports and two discharge ports. Each of the suction ports 12 and 18 is provided at a position where the minor diameter portion changes to the major diameter portion as the rotor 20 rotates counterclockwise. That is, the suction ports 12 and 18 are provided at positions where the volume of the cell C increases. The discharge ports 2 and 14 are
It is provided at a position where the long diameter portion transitions to the short diameter portion. That is, the discharge ports 2, 1 are located at the position where the volume of the cell C decreases.
4 are provided. The intake ports 12 and 18 are in communication with the intake passage 46 by a flow path in the front housing 34 (not shown). The discharge ports 2 and 14 communicate with the pressure chamber 32, and the pressure chamber 32 communicates with the flow rate adjusting valve 42 through a passage (not shown).
Communicates with a discharge passage (not shown) through a flow passage (not shown). The flow rate adjusting valve 42 also communicates with the bypass passage 43, and the bypass passage 43 communicates with the suction ports 10 and 18. The discharge ports 2 and 14 are connected to the back pressure groove 4 via the pressure chamber 32.
8, the discharge pressure is applied to the back surface 22A of the vane 22. Note that reference numeral 52 in the figure denotes a fluid circulation space.

In the case of this vane pump, when the rotary shaft 24 is rotated and the rotor 20 is rotated, the vane pump communicates with the suction ports 12 and 18 while the volume of the cell C increases, and the suction passage 4
Fluid from 6 is drawn into cell C. The fluid sucked into the cell C is pressurized as the cell volume decreases and reaches the discharge ports 2 and 14 in a pressurized state. Therefore, the pressure inside the pressure chamber 32 becomes high. This high pressure is the back pressure groove 48
Is applied to the back surface 22 </ b> A of the vane 22 via, and the vane 22 is biased to the inner peripheral surface 10 of the cam ring 8. The flow rate adjusting valve 42 supplies a constant flow rate of fluid to the discharge passage and returns excess fluid to the suction ports 12 and 18. The above is basically the same as the conventional vane pump.

In the case of the vane pump exemplified here, the pressure difference relaxing grooves 4A, 4B, 16A, 16 are formed in the side plate 6.
B is provided. The pressure difference reducing grooves 4A and 4B are provided at positions slightly facing the suction port 12 side from the discharge port 2 and are provided in two steps in the circumferential direction. That is, the pressure difference relaxing groove 4A is provided near the discharge port 2, and the pressure difference relaxing groove 4B is provided near the suction port 12. For this reason, when the cell C moves in the counterclockwise direction, the vane 22-1 preceding immediately before the cell C communicates with the discharge port 2 first passes through the pressure difference relief groove 4B and then passes through 4A. , And then communicate with the discharge port 2 (see FIG. 3). The pressure difference relaxing grooves 16A and 16B are also placed in the same positional relationship with the discharge port 14.

Next, referring to FIGS. 3 and 4, how the pressure in the cell C1 changes will be described. As shown in FIG. 3 (1), while the cell C1 communicates with the suction port 12, the cell C1 has not yet passed through the pressure difference relaxing groove 4B. If the cell C1 passes through the pressure difference reducing groove 4B while the cell C1 is in communication with the suction port 12, the pressure difference between the discharge port 2 and the suction port 12 is reduced. This positional relationship indicates the upstream side of the pressure difference relaxing groove provided in multiple stages according to the present invention, that is, the limit position near the suction port, and the pressure difference relaxing groove on the most upstream side is the downstream side thereof.
That is, it is provided on the discharge port side.

In FIG. 3 (2), the cell C1 has the intake port 1
2 is cut off and communicated with the most upstream side end portion 4B1 of the most upstream pressure difference relaxing groove (4B in this case),
Thereafter, the pressure in the discharge port 2 is introduced into the cell C1 and the pressure in the cell C1 starts to rise (see FIG. 4 ((2) to (5) on the time axis in FIG. 4 is (2) in FIG. 3). (Corresponding to the positional relationship of (5)). As well shown in (2) of FIG. 3, the circumferential length of the pressure difference relaxing groove 4B is set shorter than the thickness of the vane 22, and the pressure difference relaxing groove 4B is located on the left side and the right side of the vane 22. It does not directly connect the cells of.
The pressure difference reducing action is obtained by partially reducing the sealing action between the vane 22 and the side plate 6 by the pressure difference reducing groove 4B. Since the circumferential length of the pressure difference relaxing groove 4B is set to be equal to or smaller than the thickness of the vane 22, the cell on the left side of the vane and the cell on the right side are not directly connected by the groove 4B, and both cells are The pressure difference between them slowly relaxes. The circumferential lengths of all the pressure difference relaxing grooves 4A, 4B, 16A, 16B are set to be equal to or less than the vane thickness.

FIG. 3C shows the preceding vane 22-1.
Shows a state in which the seal portion 4C between the pressure difference relaxing grooves 4A and 4B is approaching. In this case, the sealing property between the vane 22 and the side plate 6 returns to a good state again, and it becomes difficult for high pressure in the discharge port to be introduced into the cell C1.
Therefore, the pressure increasing speed in the cell C1 decreases before and after this state. This is because during this time, only the pressure increase mainly due to the volume change of the cell C1 is obtained, and the high-pressure introduction action from the discharge port side is reduced. However, as well shown in (3) of FIG. 3, the circumferential length of the seal portion 4C, that is, the circumferential length between the groove 4A and the groove 4B is set to be equal to or less than the thickness of the vane 22, The seal 4C prevents the vane 22 and the side plate 6 from being completely sealed. Ie vane 2
Even if 2 is applied to the seal 4C, the pressure-releasing action does not disappear at all, but it is kept small.

FIG. 3 (4) shows a state in which the preceding vane 22-1 is approaching the second pressure difference reducing groove 4A,
After that time, the sealing property between the vane 22 and the side plate 6 deteriorates again, and the pressure relaxation action starts to be obtained. As a result, as shown in FIG. 4, the pressure inside the cell C1 increases its rising speed again. 3 (5) shows the positional relationship immediately after the cell C1 communicates with the discharge port 2, and thereafter the internal pressure of the cell C1 becomes equal to the discharge pressure (pressure P2 in FIG. 4).

As described above, according to this embodiment, since the pressure difference relaxing groove is provided in two stages, the pressure in the cell rises relatively rapidly in two steps (after (2) in FIG. (4)
Later). For this reason, the pressure difference relaxation action per time may be smaller than the method of relaxing the pressure difference at one time with one groove, and the dimensional dimension of each pressure difference relaxation groove can be made smaller than in the past. Therefore, even if the discharge port pressure becomes unexpectedly high, the cell pressure is prevented from rising too rapidly. Further, between the two pressure difference relaxing actions, a period in which the pressure difference relaxing action is small (before and after (3) in FIG. 4) is provided, so that the cell internal pressure is maintained regardless of whether the pressure in the discharge port is high or low. It rises smoothly.

Although the relationship between the discharge port 2 and the pressure difference relaxing groove 4 has been described with reference to FIGS. 3 and 4, the same applies to the discharge port 14 and the pressure difference relaxing groove 16. In the present embodiment, the pressure difference relaxing groove is provided in two stages, but the number of stages can be any number of three or more. Further, the pressure difference reducing grooves 4A, 4 of the present embodiment
Although B, 16A, and 16B have a deep triangular pyramid shape on the discharge port 2 and 14 side, they may have a conical shape extending in half. Alternatively, the bottom surfaces of the triangular pyramid shape or the conical shape extending in half may be combined to have a shape that looks like a diamond when viewed in a plan view. There is no particular restriction on the shape of the groove. Further, in this embodiment, the pressure difference reducing grooves 4 and 16 are provided on the side plate 6 where the discharge ports 2 and 14 are provided, but the pressure difference reducing groove may be provided on the rear plate 50 side. Alternatively, it may be provided on the inner peripheral surface 10 of the cam ring 8.

[0024]

According to the present invention, the cells defined by the two vanes, the inner peripheral surface of the cam ring and the outer peripheral surface of the rotor are brought close to the pressure on the discharge port side several times immediately before they communicate with the discharge port, The cell and the discharge port communicate with each other in a state in which the pressure is raised close to the pressure on the discharge port side. Therefore, even if the discharge port internal pressure is high, the cell internal pressure is smoothly increased toward the discharge port internal pressure, and the vane pump can be operated smoothly.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of one vane pump according to an embodiment.

FIG. 2 is a sectional view taken along line II-II of one vane pump of the embodiment.

FIG. 3 is a diagram for explaining how the pressure in the cell fluctuates.

FIG. 4 is a graph showing a variation pattern of cell internal pressure.

FIG. 5 is a view corresponding to FIG. 2 of a conventional vane pump.

FIG. 6 is a view corresponding to FIG. 3 of a conventional vane pump.

FIG. 7 is a view corresponding to FIG. 4 of a conventional vane pump.

[Explanation of symbols]

 6 Side plate 8 Ring cam 50 Rear plate The above is the pump chamber defining container of the vane pump 2,14 Discharge port 12,18 Suction port 20 Rotor 22 Vane 4A, 4B Two-stage pressure difference relaxing groove 16A, 16B Two-stage pressure difference relaxing groove

Claims (2)

[Claims] 1. A vane pump in which a rotor having a plurality of vanes rotates in a pump chamber demarcating container having a discharge port and a suction port, from the discharge port position on the inner surface of the container defining the pump chamber toward the suction port side. A vane pump having a plurality of pressure difference relaxing grooves. 2. The circumferential length of each pressure difference relaxing groove and the circumferential length between each pressure difference relaxing groove are each set to be equal to or less than the thickness of the vane. Vane pump.