JP2003097454A - Vane pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a shortage of a discharge flow rate and motive power loss by restraining the generation of the excessive moment of a cam ring when the cam ring is displaced in the minimum eccentric direction. SOLUTION: The cam ring 26 is eccentrically arranged via a piston 27 on the outer peripheral side of a rotor 24 for installing a plurality of vanes so as to freely protrude and retreat in the radial direction. A first operation chamber 31 and a second operation chamber 32 are arranged in the outer peripheral side mutually opposing positions of the cam ring for respectively pressing the cam ring in the reducing direction and the increasing direction of an eccentric quantity to a rotor by the introduction of a hydraulic fluid. The first and second operation chambers are respectively communicated with a discharge passage 39 via an orifice. A communicating passage 67 is formed for communication the suction side first operation chamber and a suction side pump chamber. When the cam ring is displaced in the minimum eccentric direction, the hydraulic fluid in the first operation chamber is made to flow in a suction port 38 from the communicating passage, and the excessive moment is restrained by reducing pressure.

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 as a drive source for power steering of a vehicle,
In particular, the present invention relates to a variable displacement vane pump that controls the discharge flow rate by changing the capacity of the pump body.

[0002]

2. Description of the Related Art As a variable displacement vane pump used in a vehicle, for example, one described in Japanese Patent Laid-Open No. 2000-161249 is known.

In this vane pump, as shown in FIGS. 9 to 11, a drive shaft 2 driven by an engine of a vehicle is rotatably inserted and supported in a pump housing 1, and a rotor 3 is integrated with the drive shaft 2. It is rotatably connected. The rotor 3 is formed with a plurality of slots in the radial direction on the outer peripheral side thereof, and the vanes 4 are housed in the slots so that the vanes 4 can retract. Further, a cam ring 6 that forms a pump chamber 5 between the rotor 3 and each vane 4 is provided on the outer peripheral side of the rotor 3. The cam ring 6 has a circular inner cam surface with which the tips of the vanes 4 are in sliding contact, and the ring-shaped member 1 provided on the outer peripheral side.
On the inner peripheral side of 9, the lower end of the outer peripheral portion is swingably supported in the pump housing 1 by a pin 7, and the eccentricity with respect to the rotor 3 can be adjusted by swinging around the pin 7. There is.

Further, as shown in FIG. 11, the cam ring 4
The inner suction region and the discharge region are connected to the suction passage 8 and the discharge passage 9, respectively, and the discharge port 1 of the discharge passage 9 is connected.
A hydraulic actuator 17 communicates with the downstream side of 6. A variable main orifice 10 is provided in series on the front side of the discharge port 16, and the control valve 11 is operated by the differential pressure across the main orifice 10. Further, the cam ring 6 is urged by the urging spring 12 in a direction to increase the eccentricity amount, and the first operation for reducing the eccentricity amount of the cam ring 6 by the hydraulic oil introduced to the opposite positions on the outer periphery of the cam ring 6. Chamber 13
On the contrary, the second working chamber 1 for increasing the eccentricity of the cam ring 6
4 are formed.

In the case of this vane pump, the hydraulic oil on the upstream side of the main orifice 10 is similarly introduced into the first and second working chambers 13 and 14, and the discharge passage 15 connected to the second working chamber 14 is connected. By controlling the opening area by the control valve 11, the eccentric amount of the cam ring 6 is adjusted by so-called meter-out control.

The control valve 11 has a valve body 11a for opening and closing the discharge passage 15 and a return spring 11b for urging the valve body 11a in a direction in which the discharge passage 15 is closed.
And a high pressure fluid chamber 11c that communicates with the upstream side of the main orifice 10 and presses the valve body 11a in a direction in which the opening area of the discharge passage 15 increases by introducing the operating oil, and a hydraulic fluid that communicates with the downstream side of the main orifice 10 Valve body 1 by the introduction of
It is provided with a low pressure fluid chamber 11d that presses 1a in a direction in which the opening area of the discharge passage 15 decreases.

The control valve 11 has a valve body 11
a changes the opening area of the discharge passage 15 in response to the differential pressure across the main orifice 10, thereby controlling the eccentric amount of the cam ring 6 so that the discharge flow rate becomes the set flow rate.

Further, in this conventional example, the hydraulic oil introduced into the first working chamber 13 from the upstream of the main orifice 10 once flows into the high pressure fluid chamber 11c of the control valve 11, and the valve body 11a becomes the low pressure fluid chamber. When it has moved to the side of 11d by a predetermined amount, it is introduced into the first working chamber 13 while the flow rate is controlled by the valve body 11a. Further, in the case of this example, the main orifice 10 is composed of a variable orifice whose opening area is reduced as the eccentricity of the cam ring 6 is reduced, and so-called flow-down characteristics are obtained by increasing the rotational speed of the rotor. ing. In the figure, 18
Is an orifice groove formed on the outer periphery of the valve body 11a.

[0009]

However, in this conventional variable displacement vane pump, when the pump discharge pressure from the discharge passage 9 becomes high or when the pump rotation speed shifts to high rotation. That is, when the eccentric amount of the cam ring 6 is about to be displaced to the minimum side, an excessive moment is generated in the cam ring 6 in the direction of the minimum eccentricity about the pin 7, and the excessive moment causes the cam ring 6 to suddenly move. There is a risk of shifting to the minimum eccentricity side.

That is, during pump operation, the load acting on the cam ring 6 becomes high on the outer peripheral side of the cam ring 6 due to the working hydraulic pressure in the first and second working chambers 13 and 14, and the inner peripheral side of the cam ring 6 is formed. Since the suction region side has a low pressure and the discharge region side has a high pressure, a load due to a pressure difference is generated in the cam ring 6 from the outside to the inside of the cam ring 6 on the suction region side. Then, the load direction is a direction (arrow direction in FIG. 9) from the suction region to the discharge region through the center P2 of the cam ring 6 at an intermediate position of the suction region.

Further, as shown in FIG. 9, the position where the suction area and the discharge area are separated is one between two adjacent vanes 4, 4 immediately before and immediately after the closing of each port (suction port, discharge port). There is a difference of 5 pump chambers, but on average from the center of the maximum port closure of the cam ring 6 in the radial direction to the center of the minimum port closure in the radial direction. Here, in the figure, a is a closed section on the suction side, and a'is a closed section on the discharge side.

When the eccentricity of the cam ring 6 is maximum, the load acting on the cam ring 6 passes through the center of the pin 7 (thick arrow) as shown in FIG. Does not occur.

However, as the rotational speed of the pump and the discharge pressure gradually increase and the eccentric amount of the cam ring 6 decreases, the suction port 8a of the suction passage 8 and the discharge port 9a of the discharge passage 9 are increased.
Does not change, and therefore, as shown in FIG.
Since the position of the center P2 of the cam ring 6 changes without changing the load direction due to the pressure difference acting on the cam ring 6, the load acting on the cam ring 6 deviates from the center P of the pin 7. Therefore, this deviation Z becomes a moment around the pin 7, and the cam ring 6 is moved in a direction in which the amount of eccentricity becomes excessively smaller than the target amount of eccentricity. This phenomenon is caused by an increase in the arm length of the moment when the pump is rotating at a high speed and an increase in the load acting on the cam ring 6 when the pump is at a high pressure. It occurs because a large moment is generated.

As a result, the pump discharge flow rate rapidly decreases at high pressure as shown in FIG. 12 until it reaches the minimum eccentricity as indicated by a thin line Q3 in comparison with Q2 at low pressure, The discharge flow rate may not be sufficiently supplied to the hydraulic actuator 17, and power loss may increase.

Therefore, according to the present invention, when the cam ring shifts from the maximum eccentric position to the minimum eccentric position, a rapid rise of the load acting on the cam ring in the minimum direction is suppressed on the suction region side of the cam ring, and the discharge flow rate is insufficient. Another object of the present invention is to provide a variable displacement vane pump capable of eliminating an increase in power loss.

[0016]

According to a first aspect of the present invention, a plurality of vanes are mounted so as to be retractable in the radial direction, and the rotor is rotationally driven by a drive shaft, and the rotor is provided on the outer peripheral side of the rotor. On the other hand, a cam ring that is eccentrically arranged around the pivotal portion and that forms a plurality of pump chambers between the outer peripheral surface of the rotor and each adjacent vane, and a suction ring that communicates with the suction area and the discharge area in the cam ring. A first operation, which is provided at a reciprocal position between the passage and the discharge passage and the cam ring on the outer circumference of the cam ring, and presses the cam ring in a direction in which the amount of eccentricity with respect to the rotor decreases and in a direction in which the amount increases by introducing hydraulic oil. Chamber and a second working chamber, and a control valve that controls the discharge flow rate of the working oil in the second working chamber in response to the differential pressure across the main orifice interposed in the discharge passage. In the variable displacement vane pump, the first and second working chambers communicate with the discharge passage through the respective orifices, and the first working chamber on the suction side communicates with the suction side pump chamber. The feature is that a communication passage is formed.

Therefore, when the pump is operated, the working oil sucked from the suction passage into the suction area in the cam ring is pressurized by the pump action of the vane, passes through the main orifice of the discharge passage, and is supplied from the discharge port to the hydraulic actuator. To be done. At this time, a pressure difference occurs before and after the main orifice, and the pressure before and after that is introduced into the high pressure fluid chamber and the low pressure fluid chamber of the control valve. In the control valve,
The valve element is operated by the balance between the force of the pressure introduced into each fluid chamber and the force of the return spring.

The hydraulic oil in the second working chamber is not discharged until the valve body moves toward the low pressure fluid chamber due to the increase in the differential pressure across the main orifice, and the cam ring is positioned at the maximum eccentric position by the force of the biasing spring. is doing. Therefore,
At this time, the pump continues to discharge with the maximum capacity, and increases the discharge flow rate substantially in proportion to the rotation speed of the rotor. At this time, the hydraulic oil upstream of the main orifice is introduced into the discharge side branch chamber separated by the seal means in the first working chamber, and the hydraulic oil upstream of the main orifice is separated into the second working chamber. Is introduced through the orifice.

When the valve body moves toward the low pressure fluid chamber due to an increase in the differential pressure across the main orifice, the discharge passage opens when the upstream side of the main orifice and the second working chamber are throttled by the orifice. Then, the hydraulic oil in the second working chamber is discharged to the discharge passage according to the amount of movement of the valve element. As a result, the cam ring moves in a direction that reduces the amount of eccentricity according to the pressure difference between the first working chamber and the second working chamber. Therefore, at this time, the pump is adjusted to have a capacity according to the differential pressure across the main orifice, and as a result, the hydraulic oil of the set discharge flow rate is supplied to the hydraulic actuator.

When the cam ring is about to shift from the maximum eccentric position to the minimum eccentric position as described above,
The hydraulic oil flowing from the discharge passage into the first working chamber is gradually sucked into each pump chamber on the suction side through the communication passage in the suction region, and the pressure in the first working chamber can be slightly lowered. Therefore, it is possible to suppress the generation of an excessive moment in the direction of the minimum eccentricity with respect to the cam ring.

According to a second aspect of the present invention, the communication passage is
It is characterized in that the passage cross-sectional area is gradually increased from the first working chamber side toward the suction side pump chamber.

According to the present invention, since the passage cross-sectional area of the communication passage gradually increases as the cam ring moves toward the minimum eccentric direction, the hydraulic oil from the first working chamber to each pump chamber on the suction side is increased. The amount of inflow of C becomes gradually larger, and it becomes possible to gradually reduce the load action on the cam ring in the direction of the minimum eccentricity when the pump rotates at a high speed.

According to a third aspect of the present invention, the communication passage is
It is characterized in that the cam ring is formed in a notch shape on the end face of the side plate disposed on one end side in the axial direction of the cam ring.

According to the present invention, since the communication passage is formed in the end face of the side plate by the notch-shaped notch,
This molding operation becomes relatively easy.

According to a fourth aspect of the present invention, there is provided sealing means for partitioning the first working chamber into a suction side branch chamber and a discharge side branch chamber near a boundary between the suction region and the discharge region inside the cam ring. The communication passage is formed on the suction side with respect to the position where the sealing means is disposed.

According to the present invention, when the cam ring is maximally eccentric when the pump is operating at low speed or low pressure,
Since the discharge side compartment forming the first working chamber is separated from the suction side compartment by the sealing means, the hydraulic oil introduced into the discharge side compartment does not leak to the suction area in the cam ring, and Since the communication passage is also formed on the suction side with respect to the position of the sealing means, the working oil in the discharge side branch chamber does not flow into the suction region even by this communication passage. Therefore, it is possible to prevent a decrease in pump efficiency at low pump rotation speed and low pressure.

According to a fifth aspect of the present invention, the one end surface of the cam ring facing the communication passage formed on the end surface of the side plate is overlapped with the communication passage in accordance with the eccentric position of the cam ring. It is characterized in that a second communication passage having a change of is formed.

According to the present invention, as the cam ring is displaced from the maximum eccentric position to the minimum eccentric position, the overlap amount of each communication passage, that is, the passage cross-sectional area can be changed. It is possible to arbitrarily change the amount of inflow into each pump chamber on the suction side.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of a variable displacement vane pump according to the present invention will be described in detail with reference to the drawings.

That is, FIGS. 1 and 2 show a first embodiment of the present invention, in which 20 is a pump housing of the present invention, and this pump housing 20 has a recess 21a for accommodating a pump main body. The housing main body 21 and a rear cover 22 that is connected to the housing main body 21 and closes the recess 21a are configured. A drive shaft 23 driven by an engine of the vehicle is rotatably supported by the pump housing 20, and a rotor 24 is integrally rotatably coupled to the drive shaft 23. The rotor 24 is
A plurality of slots are formed in the radial direction on the outer peripheral side, and the vane 25 is retractably housed in each slot.

Reference numeral 26 denotes a cam ring which constitutes a pump main body together with the rotor 24 and accommodates the rotor 24 on the inner peripheral side. The cam ring 26 has the vanes 25.
Is formed with a circular inner cam surface with which the tip of the sliding contact. Further, as will be described later, a part of the outer peripheral portion (the lower end in FIG. 1) of the cam ring 26 is swingably supported in the pump housing 20 by a pin 27 which is a balance portion, and swings about the pin 27. The amount of eccentricity with respect to the rotor 24 can be adjusted by the movement. In FIG. 1, P1 indicates the center of rotation of the rotor 24 and the drive shaft 23, and P2 indicates the center of the cam ring 26. The center P2 of the cam ring 26 is displaced in the left-right direction in FIG.

In this vane pump, since the cam ring 26 is eccentric with respect to the rotation center P1 in the normal state,
When the rotor 24 rotates while sliding the tip of the vane 25 into contact with the inner peripheral surface of the cam ring 26, the adjacent vanes 25, 2
The volume of the pump chamber formed between 5 is increased / decreased to thereby continuously operate the pump. When the eccentricity amount of the cam ring 26 and the rotor 24 changes, the volume change rate of the pump chamber changes, and the pump capacity changes accordingly.

Reference numeral 28 in the drawing denotes a pump housing 20.
Is a ring-shaped member that fits in the recess 21a and forms a housing space for the cam ring 26 therein, and 29 is a side plate that is housed in the recess 21a together with the ring-shaped member 28. The ring-shaped member 28 is made of a hard material and is slightly wider than the width of the rotor 24, the vane 25, and the cam ring 26. The inner peripheral surface of the ring-shaped member 28 is substantially elliptical so as to allow the swing displacement of the cam ring 26. It is formed into a shape. This ring-shaped member 28 is a cam ring 26.
It is engaged with a pin 27 that serves as the center of swinging, and this pin 27 prevents rotation.

A seal member 30 which is spring-biased inward in the radial direction is arranged at a position opposite to the position of the pin 27 on the inner peripheral surface of the ring-shaped member 28, and the seal member 30 serves as the cam ring 26. Is allowed to come into close contact with the outer peripheral surface of the cam ring 26 while allowing the displacement (oscillation) thereof.
This seal member 30 together with the pin 27 forms the ring-shaped member 2
The inner space of 8 is divided into a first working chamber 31 on the left side in FIG. 1 and a second working chamber 32 on the right side in FIG.
The pressure of the hydraulic oil introduced into 32 acts on the cam ring 26 in opposite directions.

Therefore, when the cam ring 26 is maximally displaced in the direction of the first working chamber 31, the eccentric amount with respect to the rotor 24 is maximized, and conversely, when the cam ring 26 is maximally displaced in the direction of the second operating chamber 32, it is the same. The amount of eccentricity is minimized.

The side plates 29 close both sides of the ring-shaped member 28 together with the inner wall of the pump housing 20 (the inner wall of the rear cover 22), and further, the rotor 24, the vanes 25, and the cam ring inside the ring-shaped member 28. Both sides of 26 are faced with a minute gap.

The side plate 29 receives the pressure of the hydraulic oil in the pump as will be described later, and the cam ring 2 receives the pressure.
It is pressed in six directions. By directly receiving the pressing force at this time by the ring-shaped member 28, smooth rotation of the rotor 24 and smooth eccentric operation of the cam ring 26 can be permitted. Further, as shown in FIG. 3, on one end surface of the side plate 29 on the cam ring 26 side, a substantially arcuate suction port 38 and a discharge port 40 are provided at the upper and lower positions in the drive shaft 23.
Is formed along the circumferential direction centering on the center P1 of the.

As shown in FIG. 2, a recess for forming a low pressure chamber 33 and a high pressure chamber 34 is formed between the recess 21a of the pump housing 20 and the side plate 29. The high pressure chamber 34 is the side plate 29.
Through the communication holes 35 and 36 formed in the cam ring 26, they are electrically connected to the suction area a (the upper half area in FIG. 1) and the discharge area b (the lower half area in FIG. 1) in the cam ring 26. There is. The suction region a in the cam ring 26 is connected to the suction port 37a of the pump housing 20 from the suction port 72 through the suction passage 37, and the discharge region b has the discharge port 40 of which the high pressure chamber 34 is a part. It is connected to the discharge port 39 c of the pump housing 20 via 39. The side plate 29 receives the pressure of the hydraulic oil in the high pressure chamber 34 and presses the ring-shaped member 28 toward the rear cover 22.

The discharge passage 39, as shown in FIG.
The high-pressure chamber 34 is branched into a first passage 39a and a second passage 39b. A first orifice 41, whose opening area can be adjusted, and a second orifice 42 having a fixed opening area are provided in each of the passages 39a and 39b. Are installed respectively. The passages 39a and 39b are rejoined and connected before the discharge port 39c, and the hydraulic oils that have passed through the passages 39a and 39b are combined to flow out to the discharge port 39c. The first orifice 41 and the second orifice 42
Configures the main orifice in the present invention, and controls the discharge flow rate by managing the differential pressure before and after the main orifice as will be described later.

On the other hand, a through hole 43 is formed in a portion of the peripheral wall of the ring-shaped member 28 facing the second working chamber 32.
A cylinder hole 44 having a diameter slightly smaller than that of the through hole 43 is provided at a position continuous with the through hole 43 on the peripheral wall of the pump housing 20. This cylinder hole 44
Includes a bottomed cylindrical feedback plunger 45,
An urging spring 46 that urges the plunger 45 is housed therein, and the tip end portion of the feedback plunger 45 projects into the second working chamber 32 through the through hole 43. The tip of the feedback plunger 45 has a cam ring 26.
Abutting against the outer peripheral surface of the cam ring 2
6 in the direction of the first working chamber 31 (direction in which the amount of eccentricity is maximized)
Is urged to.

Further, the cylinder hole 44 has a first passage communicating with the first passage 39a (discharge passage 39) on the high pressure chamber 34 side.
Port 47 and a second port 48 communicating with the discharge port 39c side of the passage 39a are formed so as to be axially separated from each other, and these ports 47 and 48 are formed on the outer peripheral surface of the feedback plunger 45. It communicates through the annular groove 49. The first and second ports 47, 48 and the annular groove 49 serve as the first orifice 4 described above.
The feedback plunger 4 is a part of the feedback plunger 4.
Ports 47 and 48 and annular groove 49 with 5 being most protruded
The maximum overlap (passage opening area), and conversely with the plunger 45 retracted most, the ports 47, 48
And the annular groove 49 overlap (passage opening area) is minimized.

Further, in the vicinity of the tip of the feedback plunger 45, an orifice passage 50 that connects the inside of the plunger 45 and the second working chamber 32 is formed.
The working oil in the working chamber 32 is supplied to and discharged from the back chamber 51 (the space formed between the feedback plunger 45 and the bottom of the cylinder hole 44) through the orifice passage 50. Therefore, the feedback plunger 45 can freely move back and forth in the cylinder hole 44, and when the plunger 45 tries to suddenly move backward and forward, a large flow resistance is generated in the orifice passage 50 portion, which functions as a so-called dashpot. To do.

Further, the ring-shaped member 28 is provided with a flat-shaped restricting wall 52 for restricting the displacement of the cam ring 26 in the direction of increasing the eccentric amount, at a position facing the first working chamber 31 on the inner peripheral surface thereof. Has been. This restriction wall 52 is a suction area a
Although it is located near the boundary line s between the discharge area b and the discharge area b, an elastic material such as a rubber material is provided in the inner peripheral surface of the ring-shaped member 28 at a position slightly closer to the suction area a than the regulation wall s. A seal member 53, which is a sealing means composed of, is attached. The seal member 53 contacts the outer peripheral surface of the cam ring 26 immediately before the eccentric amount of the cam ring 26 becomes maximum,
The inside of the first working chamber 31 is divided into a suction side branch chamber 31a and a discharge side branch chamber 31b.

Further, a first conduction hole 54 and a second conduction hole 55 are formed in the portions of the side plate 29 facing the first working chamber 31 and the second working chamber 32, respectively. Through the holes 54 and 55 of the first working chamber 31 and the second working chamber 31.
The working chambers 32 are communicated with each other.

Incidentally, the first working chamber 31 and the second working chamber 32
It is conceivable to form a conduction hole in the ring-shaped member 28 made of a hard material as a means for communicating the discharge passage 39 (the high pressure chamber 34 and the like) with each other. However, as in this embodiment, the side plate 29 has a conduction hole 54, In the case of forming 55, the side plate does not need to be formed of a hard material like the ring-shaped member 28, and since the drilling process is easy, the manufacturing cost can be further reduced.

The first communication hole 54 communicates with the discharge side branch chamber 31b of the first working chamber 31, and the inside of the first working chamber 31 is completely connected to the suction side branch chamber 31a and the discharge side branch chamber 31b. Even when separated, the hydraulic oil in the high pressure chamber 34 is surely introduced into the discharge side branch chamber 31b. Further, the first and second communication holes 54 and 55 are formed to have a small diameter so that they function as orifices that limit the inflow rate of the hydraulic oil from the high pressure chamber 34 to the first and second working chambers 31 and 32. Has become.

The second working chamber 32 has the second conducting hole 5
5, the ring-shaped member 28 to the pump housing 20
It communicates with the discharge passage 56 formed through The discharge passage 56 is a passage that connects the second working chamber 32 and the low-pressure chamber 33, and a control valve 57 that controls the discharge flow rate of the working oil is interposed in the passage.

As shown in FIG. 1, the control valve 57 has a valve chamber 58 formed in the pump housing 20 in which a cylindrical valve body 59 having a bottom is housed. It is divided into a chamber 60 and a low pressure fluid chamber 61. The high pressure fluid chamber 60 includes the first and second orifices 41 and 42.
The high pressure chamber 34 is connected to the upstream side of the (main orifice), and the low pressure fluid chamber 61 is connected to the first and second orifices 41 and 42.
The valve body 59 is connected to the discharge port 39c on the downstream side of the (main orifice) and the high pressure fluid chamber 6 is provided therein.
A return spring 63 that biases the 0 side is housed.

The upstream port 64 and the downstream port 65 of the discharge passage 56 are opened at positions axially separated from each other in the valve chamber 58, and both ports 6 are formed on the outer peripheral surface of the valve body 58.
An annular groove 66 capable of communicating the four and 65 is formed. The annular groove 66 does not overlap with the upstream port 64 when the valve body 59 is pressed by the return spring 63 toward the high pressure fluid chamber 60, and the valve body 59 resists the force of the return spring 63 and the low pressure fluid. When it is displaced toward the chamber 61 side, the upstream port 64 and the downstream port 65 overlap depending on the displacement. Therefore, with this control valve 57, the valve element 59 has the first and second orifices 41, 42 with the above configuration.
It responds to the differential pressure across the (main orifice) and controls the opening area of the discharge passage 56 according to the displacement.

A drain passage (not shown) communicating with the low pressure chamber 33 in the pump housing 20 is connected to the low pressure fluid chamber 61 of the control valve 57, and a relief valve is provided in this drain passage. This relief valve has a well-known structure that opens due to the balance between the hydraulic oil and the biasing spring, and the pressure in the low-pressure fluid chamber 61 exceeds the set pressure due to the increase in the load pressure of the discharge port 39c (hydraulic actuator 70). It is set so that the drain passage 71 is opened when it becomes.

The side plate 29 has a structure as shown in FIG.
Further, as shown in FIG. 3, a notch-shaped communication passage 67 is formed on one end surface where the suction port 38 is formed so as to connect the substantially central outer end portion of the suction port 38 and the first working chamber 31. There is. That is, the communication passage 67 is formed in an acute arrowhead shape, and the distal end 67b is inclined along the eccentric rocking direction of the cam ring 26 from the base end portion 67a formed continuously in substantially the center of the suction port 38. In addition to being formed in a shape, the passage cross-sectional area is formed in an expanded shape such that the cross-sectional area of the passage gradually increases from the tip edge 67b to the base end portion 67a. Therefore, the opening area of the communication passage 67 changes depending on the relative relationship with the eccentric amount of the cam ring 26 as shown in FIG. 4, and the cam ring 26 is opened to the maximum at the minimum eccentric position and the cam ring 26 is displaced in the maximum eccentric direction. Then, the opening area is reduced in proportion to this. Further, the entire position is formed closer to the suction port 38 than the position of the seal member 53, and faces only the suction side branch chamber 31a.

In the above structure, when the drive shaft 23 rotates by starting the engine, as shown in FIG. 1, the rotor 24 rotates inside the cam ring 26 with the cam ring 26 displaced to the maximum eccentric position. Thus, when the rotor 24 rotates, the pump operation is continuously performed in the cam ring 26, and the hydraulic oil pressurized by the vane 25 is discharged from the discharge area b to the high pressure chamber 34. The hydraulic oil discharged into the high pressure chamber 34 passes through the orifices 41 and 42 of the first and second passages 39a and 39b and is supplied from the discharge port 39c to the hydraulic actuator 70, while the hydraulic oil of the side plate 29 is discharged. First and second conduction holes 5
The first working chamber 31 and the second working chamber 32 through 4,55
Will be introduced to.

At this time, the first and second orifices 41, 4
A differential pressure is generated before and after 2, and the differential pressure acts on the valve body 59 of the control valve 57. The valve body 59 is pressed against the high pressure fluid chamber 60 side by the return spring 63 until the differential pressure reaches a set value. The discharge passage 56 is closed. Therefore, the pressure of the second working chamber 32 is not discharged to the outside and is maintained at substantially the same pressure as that of the first working chamber 31, and the cam ring 26 of the urging spring 46 as shown in FIG. The maximum eccentric position is maintained by the force, and the discharge flow rate increases substantially in proportion to the increase in the rotation speed of the rotor 24 until the differential pressure across the first and second orifices 41 and 42 becomes equal to or higher than the set pressure.

By the way, at this time, the cam ring 26 is in contact with the restriction wall 52 by being displaced to the maximum eccentric position, and slightly closer to the suction area a than the contact portion of the outer peripheral surface of the cam ring 26 with the restriction wall 52. The seal member 53 is in contact. Therefore, the inside of the first working chamber 31 has the sealing member 5
3 separates the suction side branch chamber 31a and the discharge side branch chamber 31b, and cuts off the flow of the hydraulic oil between the suction side branch chamber 31a and the discharge side branch chamber 31b. In this state, the hydraulic oil in the high pressure chamber 34 is introduced into the discharge side branch chamber 31b, so that the pressure acts on the outer peripheral surface of the cam ring 26 in the discharge side branch chamber 31b, but does not act in the suction side branch chamber 31a.

Therefore, at this time, in the suction side branch chamber 31a, the working oil leaks to the low pressure suction region a in the cam ring 26 through a minute gap on the side of the cam ring 26, but is introduced from the high pressure chamber 34 to the discharge side branch chamber 31b. The high-pressure hydraulic oil thus generated does not leak into the suction area a via the suction side compartment 31a. Therefore, in this state where the cam ring 26 is displaced to the maximum eccentric position and a large discharge flow rate is required, leakage of high-pressure hydraulic oil from the first working chamber 31 hardly occurs, and a sufficient discharge flow rate as desired is obtained. Can be supplied to the hydraulic actuator 70. Also, since there is no unnecessary leakage of hydraulic oil, power loss is also reduced.

Further, when the rotational speed of the rotor 24 increases from this state and the differential pressure across the first and second orifices 41, 42 becomes equal to or higher than the set pressure, the valve element 59 of the control valve 57 becomes low due to the differential pressure. It is displaced in the direction of the fluid chamber 61, and the discharge passage 56 is opened with an opening area corresponding to the displacement. As a result, the hydraulic oil in the second working chamber 32 is discharged into the discharge passage 56.
The pressure in the working chamber 32 is reduced to a pressure corresponding to the opening area of the discharge passage 56. Therefore, the cam ring 26 is displaced according to the differential pressure across the first and second orifices 41 and 42, and the pump capacity is adjusted so that the set discharge flow rate is achieved.

Then, in the initial stage of the cam ring 26 starting to be displaced from the maximum eccentric position in the direction of decreasing the eccentric amount, the seal member 53 is brought into close contact with the outer peripheral surface of the cam ring 26 to suck the inside of the first working chamber 31. Side branch 3
The cam ring 26 receives the pressure of the hydraulic oil on the upstream side of the orifices 41, 42 only by the region facing the discharge side branch chamber 31b because it is separated from the discharge side branch chamber 31b.
However, in this embodiment, the suction area a and the discharge area b are
Since the seal member 53 is arranged at a position closer to the suction region a side with respect to the boundary line s (boundary point), the shortage of the pressure receiving area in the initial operation of the cam ring 26 is minimized. Therefore, in this embodiment, good operation responsiveness of the cam ring 26 can be ensured even in the initial operation of the cam ring 26.

Thereafter, when the rotational speed of the pump increases and the pump discharge pressure increases, the cam ring 26 separates from the seal member 53 due to the increase in the hydraulic pressure in the first working chamber 31, and the suction side branch chamber 31a and the discharge side chamber 31a. The separation from the compartment 31b is released. Therefore, the cam ring 26 receives the pressure of the high-pressure hydraulic oil over the entire outer peripheral surface facing the first working chamber 31. Therefore, the cam ring 26 operates more responsively thereafter.

The cam ring 26 from the maximum eccentric position
When the seal member 53 separates from the cam ring 26 due to the displacement of No. 1, if a large amount of hydraulic oil flows into the intake side branch chamber 31a, a large amount of hydraulic oil leaks into the intake area a through the gap at the side of the cam ring 26. Is a concern,
In this embodiment, since the first communicating hole 54 communicating with the high pressure chamber 34 is formed to have a small diameter, the rapid inflow of the hydraulic oil into the first working chamber 31 at this time is caused by the communicating hole 54.
Is restricted by the orifice function, and the leakage of hydraulic oil to the suction area a is suppressed to a small extent.

On the other hand, when the cam ring 26 is displaced by the control of the control valve 57 as described above, the feedback plunger 45 moves rightward in FIG. 1 to follow the displacement, and the opening area of the first orifice 41 becomes the movement amount. Adjust accordingly. Therefore, as shown in FIG. 5, the cam ring 26 reduces the amount of eccentricity (the second working chamber 32
Direction), the opening area of the first orifice 41 is reduced according to the displacement. As a result, the vane pump reduces the discharge flow rate in opposition to the rotation speed of the rotor 24, and exhibits a so-called flow-down characteristic.

Then, as described above, the first working chamber 31
When the cam ring 26 is about to be displaced toward the minimum eccentricity due to the high hydraulic pressure supplied to the cam ring 26, a part of the hydraulic oil in the first working chamber 31 first flows in from the tip edge 67b of the communication passage 67, and the cam ring 26 The gas flows into each pump chamber through the suction port 38 from the opening that is gradually enlarged in accordance with the displacement amount of 26 in the minimum eccentric direction. Therefore, the hydraulic pressure in the first working chamber 31 can be slightly reduced. Therefore, it is possible to suppress the generation of an excessive moment around the pin 27 due to a large load in the direction of minimum eccentricity with respect to the cam ring 26. As a result, as shown in FIG. 6, the pump discharge amount is prevented from rapidly decreasing even when the pressure is high (Q1), and it is possible to secure the target set amount that is substantially the same as that when the pressure is low (Q2).

Further, since the opening area of the communication passage 67 is formed so as to gradually increase in accordance with the amount of displacement of the cam ring 26 in the minimum eccentric direction, the communication passage 67 extends from the suction port 38.
Since the amount of inflow to the cam ring 26 can be gradually increased, the eccentric speed of the cam ring 26 can be gradually decreased as it is displaced in the minimum eccentric direction, and the occurrence of the excessive moment can be efficiently suppressed. As a result, it is possible to reduce the pump discharge flow rate shortage and the power loss during the displacement to the minimum eccentric position.

Moreover, since the communication passage 67 is formed on the suction side of the seal member 53, the hydraulic oil flows from the first working chamber 31 into the communication passage 67 in the initial low rotation state of the pump. Since it is prevented, it is possible to sufficiently secure the pump discharge amount at such a time point, and it is possible to prevent a decrease in pump efficiency.

Further, the communication passage 67 is connected to the side plate 29.
Since the one end face of the is formed in a notch shape, the forming operation is also easy.

On the other hand, when the differential pressure across the first and second orifices 41, 42 decreases from the target eccentric position such as the minimum eccentric position of the cam ring 26, the cam ring 26 receives the force of the biasing spring 46 to perform the first operation. It is displaced toward the chamber 31.
At this time, when the cam ring 26 is displaced to the vicinity of the maximum eccentric position, the ring 26 comes into contact with the seal member 53 before coming into contact with the regulation wall 52, and gradually compresses and deforms the seal member 53. As a result, the cam ring 26 is cushioned by the elasticity of the seal member 53, and the operating speed is sufficiently reduced when it comes into contact with the regulation wall 52. Therefore, no abnormal noise is generated due to the contact of the cam ring 26 with the restriction wall 52.

Further, when the load on the hydraulic actuator 70 increases and the load pressure on the discharge port 39c rises above the set pressure, the relief valve 68 opens the drain passage 71, and the working oil in the discharge port 39c flows into the low pressure fluid chamber 61. Exhausted through. At this time, the valve body 59 simultaneously opens the discharge passage, so that the pressure in the second working chamber 32 is reduced and the cam ring 26
Moves to a position where the amount of eccentricity is minimized, as shown in FIG. The pump capacity is thus controlled to a minimum.

7 and 8 show a second embodiment of the present invention, in which the communication passage 67 is formed on the outer peripheral side of one end surface of the side plate 29, while the communication path 67 is formed on the opposite end surface of the cam ring 26. A second communication passage 68 that communicates with the passage 67 is formed.

More specifically, the communication passage 67 has
As shown in FIGS. 7A, 7B, and 8, the side plate 2
9 is formed in a rectangular shape in the circumferential direction so as to overlap with the inner peripheral side of the ring-shaped member 28 on the one end surface of the cam ring 26 and the outer peripheral portion of the cam ring 26 at the maximum eccentric position, and the formation position is determined by the seal member 53 Is also set on the inhalation side.
On the other hand, the second communication passage 68 is formed in a groove shape on the inner peripheral side of the facing end surface of the cam ring 26 along the radial direction, and has a base end portion 68.
“A” communicates with the suction port 38, and the tip portion 68b is formed in an arc shape. And, these two communication passages 67,
As shown in FIG. 7A, the overlapping amount of 68 is such that the tip portion 68 b is at the maximum eccentric position of the cam ring 26 and the communication path 6
7 is set to be the largest, and is set to be gradually smaller as the cam ring 26 is displaced to the minimum eccentric position as shown in FIG. 7B.

Therefore, according to this embodiment, the hydraulic oil in the first working chamber 31 flows between the maximum eccentric position (FIG. 7A) and the minimum eccentric position (FIG. 7B) of the cam ring 26. , 68 to flow into the suction port 38 and suppress the generation of an excessive moment with respect to the cam ring 26, and of course, the same operation and effect as in the first embodiment can be obtained. Since the opening area can be freely changed, the flow rate of the hydraulic oil can be adjusted. This improves the degree of freedom in adjusting the load acting on the cam ring 26.

The present invention is not limited to the configuration of each of the above-described embodiments. For example, the seal member 53 is not limited to a soft material and may be formed of a hard material such as metal. In this case, the restriction wall 52 that restricts the displacement of the cam ring 26 in the maximum eccentric direction can be omitted.

[0071]

As is apparent from the above description, claim 1
According to the invention described in (1), when the cam ring is about to undergo oscillating displacement from the maximum eccentric position to the minimum eccentric position, the hydraulic oil that has flowed into the first working chamber from the discharge passage passes through the communication passage in the suction region. The pressure in the first working chamber can be slightly reduced by gradually sucking into each pump chamber on the suction side. Therefore, it is possible to suppress the generation of an excessive moment in the direction of the minimum eccentricity with respect to the cam ring. As a result, it is possible to reduce the pump discharge flow rate shortage and the power loss during the displacement to the minimum eccentric position.

According to the second aspect of the present invention, the passage cross-sectional area of the communication passage gradually increases as the cam ring moves toward the minimum eccentric direction. Therefore, each pump from the first working chamber to the suction side is increased. The amount of hydraulic oil flowing into the chamber gradually increases,
It becomes possible to gradually reduce the load action on the cam ring in the direction of the minimum eccentricity when the pump rotates at high speed.

According to the third aspect of the present invention, since the communication passage is formed by the notch-shaped notch in the end surface of the side plate, the work of forming the communication passage is facilitated.

According to the fourth aspect of the invention, when the cam ring is maximally eccentric when the pump is rotating at a low speed, the discharge side branch chamber constituting the first working chamber is sealed against the suction side branch chamber. Since it is separated by the means, the hydraulic oil introduced into the discharge side compartment does not leak to the suction area in the cam ring, and it is possible to prevent a decrease in pump efficiency when the pump is rotating at a low speed.

Moreover, since the communication passage is also formed on the suction side with respect to the position of the sealing means, the working oil in the discharge side branch chamber does not flow into the suction region even by this communication passage. It is possible to prevent a decrease in pump efficiency when the pump is rotating at a low speed.

According to the fifth aspect of the invention, as the cam ring is displaced from the maximum eccentric position to the minimum eccentric position, the overlap amount of each communication passage, that is, the opening area can be freely changed. The amount of inflow from the first working chamber to each pump chamber on the suction side can be arbitrarily changed, whereby the degree of freedom in adjusting the load acting on the cam ring can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view taken along the line AA and the line BB in FIG. 2 showing a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the first embodiment of the present invention.

FIG. 3 is a front view of a side plate showing a communication path used in the present embodiment.

FIG. 4 is a characteristic diagram showing a relative change between an opening area of a communication passage and an eccentric amount of a cam ring of the present embodiment.

5 is a cross-sectional view taken along the line AA of FIG. 2 showing a state where the cam ring of the present embodiment is displaced to the minimum eccentric position.

FIG. 6 is a characteristic diagram showing a relationship between a pump discharge amount and a pump rotation speed in the present embodiment.

FIG. 7 shows the second embodiment, in which A shows the overlap amount of both communication passages at the maximum eccentric position of the cam ring,
9B is a cross-sectional view of a main portion showing the overlapping amount of both communication passages at the minimum eccentric position.

FIG. 8 is a sectional view taken along the line CC of FIG. 7A showing the second embodiment.

FIG. 9 is a sectional view of a main part of a conventional variable displacement vane pump.

FIG. 10 is a cross-sectional view of essential parts showing the action of the conventional vane pump.

FIG. 11 is a schematic configuration diagram of the conventional vane pump.

FIG. 12 is a characteristic diagram showing a relationship between a pump discharge amount and a pump rotation speed in the conventional vane pump.

[Explanation of symbols]

23 ... Drive shaft 24 ... Rotor 26 ... Cam ring 28 ... Ring-shaped member 29 ... Side plate 31 ... First working chamber 31a ... Intake side branch chamber 31b ... Discharge side branch chamber 32 ... Second working chamber 37 ... Inhalation passage 38 ... Inhalation port 39 ... Discharge passage 40 ... Discharge port 41 ... 1st orifice (main orifice) 42 ... Second orifice (main orifice) 53 ... Sealing member (sealing means) 56 ... Discharge passage 57 ... Control valve 67 ... Communication passage 68 ... Second communication passage a ... Inhalation area b ... Discharge area

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3H040 AA03 BB04 BB05 BB11 CC01                       CC09 DD03 DD14 DD21                 3H044 AA02 BB05 CC01 CC19 DD03                       DD09 DD35

Claims (5)

[Claims] 1. A rotor in which a plurality of vanes are mounted so as to project and retract in a radial direction, and is rotationally driven by a drive shaft, and a rotor is arranged on the outer peripheral side of the rotor so as to be eccentric about a pivotal portion with respect to the rotor, A cam ring that forms a plurality of pump chambers between the outer peripheral surface of the rotor and adjacent vanes, a suction passage and a discharge passage that respectively communicate with a suction region and a discharge region in the cam ring, and the cam ring on the outer periphery of the cam ring. A first working chamber and a second working chamber, which are provided at opposite positions sandwiching between the first and second working chambers, respectively. A variable displacement vane pump equipped with a control valve that controls the discharge flow rate of hydraulic oil in the second working chamber in response to the differential pressure across the main orifice. The first and second working chambers are respectively connected to the discharge passage through the orifices, and a communication passage is formed to connect the first suction-side working chamber and the suction-side pump chamber. A variable displacement vane pump characterized in that 2. The variable displacement type of claim 1, wherein the communication passage is formed so that a cross-sectional area of the passage gradually increases from the first working chamber side toward the suction side pump chamber. Vane pump. 3. The variable displacement vane pump according to claim 1, wherein the communication passage is formed on an end surface of a side plate disposed on one end side in the axial direction of the cam ring. 4. A seal means for partitioning the first working chamber into a suction side chamber and a discharge side chamber in the vicinity of a boundary between the suction region and the discharge region inside the cam ring, and the communication passage is sealed by the seal means. The variable displacement vane pump according to any one of claims 1 to 3, wherein the vane pump is formed on the suction side with respect to the arrangement position of the means. 5. A second communication passage having an overlap amount with the communication passage that changes depending on an eccentric position of the cam ring, on one end surface of the cam ring facing the communication passage formed on the end surface of the side plate. The variable displacement vane pump according to claim 3 or 4, wherein a passage is formed.