JPH0627834Y2 - Variable displacement liquid pump - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention is designed to suck and discharge liquid by rotationally driving a rotating body.
The present invention relates to a variable displacement liquid pump that can change the amount of discharged liquid.

[Conventional technology]

Conventionally, in a variable displacement swash plate type piston pump as a variable displacement liquid pump of this type, as shown in FIG. 4, a side plate 2 is fixedly installed on an opening side of a housing 1 having one side surface opened to form a main body 3. Then, a cylinder block 5 as a rotating body that is rotatably driven by a drive shaft 4 is rotatably supported in the main body 3, and a piston is inserted into a plurality of piston holes 6 formed at equal intervals in the circumferential direction in the cylinder block 5. 7 is slidably inserted in the axial direction, and a pump chamber 8 having an opening at one end surface is defined and formed. One end surface of the cylinder block 5 in which the pump chamber 8 is opened is in sliding contact with a valve plate 9 fixed in the main body 3, and the valve plate 9 is formed in a disc shape and has a semi-arcuate shape as shown in detail in FIG. The suction port 10 and the discharge port 11 are formed so as to penetrate, and a notch groove for pre-expansion is formed at the start end of the suction port 10 and a notch groove for pre-compression is formed at the start end of the discharge port 11. is doing. Intake port 10 of valve plate 9
And the discharge port 11 are the liquid suction passages 12 formed in the main body 3.
And the cylinder block 5 while communicating with the discharge passage 13.
The rotation of the pump chambers 8 allows the pump chambers 8 to communicate alternately. A swash plate 14 as a discharge amount changing member is tiltably supported in the main body 3, and a piston 7 slidably fitted in a cylinder block 5 is engaged with the swash plate 14. When the discharge pressure reaches the set pressure of the pressure control valve, the pressure liquid is introduced into the working chamber 15 formed at the back of the operation piston 16 that abuts against the swash plate 14. The liquid is led out, and the operation piston 16 is provided so as to be movable in the axial direction by the introduction of the pressure liquid into the working chamber 15 and the discharge of the liquid from the working chamber 15, and the swash plate 14 is provided with the piston 16 and the spring 17 that move in the axial direction. The tilt angle can be freely changed by the opposing action of. Along with the change of the tilt angle of the swash plate 14, the axial sliding amount of the piston 7 engaged with the swash plate 14 is changed to change the maximum capacity of the pump chamber 8 to change the discharge liquid amount. In the fourth illustrated state, the liquid in the working chamber 15 is drawn out, the tilt angle of the swash plate 14 is maximized by the force of the spring 17, and the axial sliding amount of the piston 7 is maximized.

When the drive shaft 4 is rotationally driven in this state, the suction passage 12
The liquid sucked into the pump chamber 8 through the suction port 10 is discharged from the discharge flow path 13 through the discharge port 11, and when the discharge pressure is equal to or lower than the set pressure of the pressure control valve, the working chamber 1
The liquid of No. 5 is discharged, and the swash plate 14 maximizes the tilting angle by the force of the spring 17 to obtain the maximum amount of discharged liquid. And
When the discharge pressure rises to the set pressure of the pressure control valve, the pressure liquid is introduced into the working chamber 15, and the swash plate 14 is pressed by the axial movement of the operation piston 16 to resist the spring 17 force and tilt the tilt angle. Is minimized, the amount of axial sliding of the piston 7 is minimized, and the amount of discharged liquid is minimized.

[Problems to be solved by the invention]

However, in the pump having such a configuration, at a discharge pressure equal to or less than the set pressure of the pressure control valve that maximizes the discharge liquid amount, the discharge amount is large and the pressure is low, and the suction port 12 and the discharge port 13 are driven by the rotational driving of the cylinder block 5. There is a small pressure difference between the communication of the suction port 12 and the communication of the discharge port 13 in the pump chamber 8 communicating alternately with each other, and the notch groove for pre-expansion and the discharge port 13 which are connected to the start end of the suction port 12 are connected. The pump chamber 8 is formed by a pre-compression notch groove continuously provided at the start end.
Suppresses sudden pressure fluctuations in the inside to generate less pump noise, but at the set discharge pressure that minimizes the discharge liquid volume,
There is almost no discharge amount, the pressure is high, the pressure difference between the communication of the suction port 12 and the communication of the discharge port 13 in the pump chamber 8 is large, and the pump chamber 8 has a notch groove continuously provided at the start ends of the ports 12 and 13. There was a problem that pump noise was generated because the rapid pressure fluctuation inside could not be suppressed.

The present invention solves such a problem, and provides a variable displacement liquid pump capable of reducing pump noise irrespective of the maximum and minimum discharged liquid amounts.

[Means for solving problems]

For this reason, the present invention is directed to a two-valve structure having a semi-circular suction port and a discharge port penetrating through a main body in which a liquid suction flow path and a discharge flow path are formed. A plate is provided so as to be rotatable relative to one another, and a rotary body that is in sliding contact with one of the valve plates is rotatably supported in the main body. It is equipped with a plurality of pump chambers that alternately communicate with the ports to suck and discharge liquid, and a pressure control valve that sets the discharge pressure to a set pressure is provided in the main body. Below the set pressure, the discharge liquid amount is maximized,
A discharge amount changing member that minimizes the discharge liquid amount when the discharge pressure reaches the set pressure is provided inside the main body, and one valve plate that slides in contact with the rotating body is connected to the sliding contact surface with the rotating body and is connected to the start end of the suction port. To form a notch groove for pre-expansion, and to form a notch groove for pre-compression by connecting to the start end of the discharge port, and forming a notch groove for pre-compression in the other valve plate at each port of one valve plate. The protruding part to be inserted is provided so as to project, and when the discharge pressure reaches the set pressure,
An actuator for rotating the two valve plates relative to each other is provided so that the protrusion inserted into each port of one valve plate comes into contact with the start end of the port rather than being separated from the start end of each port. A groove is formed in the end face on the protruding side so as to be connected to a notch groove continuously provided at the starting end by abutting the starting end of each port on one valve plate.

[Action]

In the configuration of the present invention, at a discharge pressure equal to or lower than the set pressure of the pressure control valve that maximizes the discharge liquid amount, the suction port, the protrusion inserted into the discharge port, and the start end of each port do not contact each other, and the suction port The pre-expansion notch groove that is connected to the start end of the pump and the pre-compression notch groove that is connected to the start end of the discharge port prevent sudden pressure fluctuation in the pump chamber that communicates alternately with the suction port and the discharge port. Suppress. Further, at the discharge pressure of the set pressure of the pressure control valve that minimizes the discharge liquid amount, the relative rotation of the two valve plates by the actuator causes the protrusions inserted into the suction port and the discharge port and the start end of each port to move. As a result, the end side of the protrusion becomes the starting end of each port and the starting end of each port recedes, and each notch groove is connected to the groove formed in the protrusion and the length thereof becomes longer. The pre-expansion and pre-compression effects are increased, and the pressure difference between the suction port communication and the discharge port communication is larger than when the discharge pressure is lower than the set pressure. It can be reduced.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 18 denotes a hollow housing having an opening on one side, and a side plate 19 is fixedly provided on the one side to close the opening to form a main body 20. A drive shaft 23 is rotatably supported in the main body 20 via bearings 21 and 22. The drive shaft 23 has a cylinder block 2 as a rotating body via a spline portion 24 formed in an intermediate portion.
Both 5 are rotatably supported. The cylinder block 25 has a piston chamber 27 slidably fitted in a plurality of piston holes 27 formed at equal intervals on the same circumference to define a pump chamber 46 opened at one end surface. A shoe 29 supported by a retainer 28 is attached to the tip of the piston 26, and abuts and engages with a swash plate 30 as a discharge amount changing member via the shoe 29. Swash plate 3
No. 0 is supported in the main body 20 so as to be inclined with respect to the axis of the drive shaft 23, and can be tilted within a fixed tilt angle range.
Reference numeral 31 is a spring interposed between the rear surface of the swash plate 30 on which the tip of the piston 26 abuts via the shoe 29 and the inner side surface of the main body 20, and always maximizes the tilt angle of the swash plate 30. The spring force is applied to the swash plate 30. Therefore, in this state, when the drive shaft 23 is rotationally driven to rotate the cylinder block 25, the piston 26 reciprocally slides with the maximum axial sliding amount, and the maximum discharge amount is obtained. Further, the maximum discharge amount can be adjusted by changing the maximum tilt angle of the swash plate 30 by advancing and retracting the adjusting bolt 32. Reference numeral 33 denotes an operation piston that is slidably inserted in the axial direction of a guide 34 that is provided so as to project from the side plate 19 into the main body 20, and that introduces a pressure liquid into a working chamber 35 formed on the back side or a liquid in the working chamber 35. Is derived to slide in the axial direction to change the tilt angle of the swash plate 30. Reference numeral 35A denotes a pressure control valve which, when the discharge pressure is less than or equal to a set pressure, draws out the liquid in the working chamber 35 to maximize the amount of discharged liquid, and when the discharge pressure reaches the set pressure, introduces the pressure liquid into the working chamber 35. The amount of discharged liquid is minimized. Reference numeral 36 denotes a liquid suction flow path formed in the main body 20, and 37 denotes a liquid discharge flow path formed in the main body 20. 38 is the main body 2
A disc-shaped valve plate fixedly installed in the inside of the valve 0 has a suction port 39 communicating with the suction flow passage 36 and a discharge port 40 communicating with the discharge flow passage 37, as shown in detail in FIGS. 2 and 3, respectively. It is formed to penetrate in an arc shape. The valve plate 38 is integrally formed with projections 41 and 42 projecting from the penetration forming portions of the ports 39 and 40 on the end surface side opposite to the end surface fixed to the main body 20. The projecting portions 41, 42 have a flat end surface on the projecting side,
Grooves 43 and 44 are formed as depressions on the flat surface. Reference numeral 45 is a disc-shaped valve plate that overlaps with the projections 41 and 42 of the valve plate 38 and is in sliding contact with the opening end surface of the pump chamber 46 of the cylinder block 25. The suction port 39 and the discharge port 40 of the valve plate 38 are respectively provided. A suction port 47 and a discharge port 48 that are in communication and have the same shape
Is formed through. The rotation of the cylinder block 25 causes the pump chambers 46 to communicate with the suction ports 47 and the discharge ports 48 alternately. Valve plate 45
To the ports 47, 48 of the valve plate 38,
2 is slidably inserted to rotatably support the valve plate 45, and when the valve plates 38 and 45 are superposed, the protrusion 4 of the valve plate 38 is formed.
The end faces 1, 42 are in sliding contact with the end face of the opening of the pump chamber 46 of the cylinder block 25.

When the discharge pressure is equal to or lower than the set pressure of the pressure control valve 35A, the valve plate 45 draws the liquid in the working chamber 50 of the piston 49 to the second illustrated position by the force of the spring 51, as shown in detail in FIG. The discharge pressure is held and the pressure control valve 35A
When the set pressure becomes, the working force of the pressure liquid introduced into the working chamber 50 of the piston 49 rotates clockwise against the force of the spring 51, and the starting ends of the ports 47 and 48 come into contact with the protrusions 41 and 42. It is provided so as to be rotatable relative to the valve plate 38 so that the valve plate 38 and the valve plate 38 are held by the piston 49, the working chamber 50, and the spring 51. 52 is the cylinder block 2 of the valve plate 45
5, a notch groove for pre-expansion which is continuously formed at the start end of the suction port 47 on the slide contact surface with 5, and is formed as a recess so as to gradually increase toward the start end, and 53 is discharged to the slide contact surface of the valve plate 45 with the cylinder block 25. It is a notch groove for pre-compression formed continuously with the starting end of the port 48 and formed so as to gradually increase toward the starting end, and is not included in the port length of each of the ports 47 and 48. The cutout grooves 52 and 53 are connected to the grooves 43 and 44 provided on the projecting end surfaces of the projecting portions 41 and 42, respectively, to increase the length thereof in the state where the amount of discharged liquid is minimum, so that the action of pre-expansion and pre-compression can be achieved. It is provided to increase.

Next, the operation of this configuration will be described.

In the first illustrated state, the swash plate 30 maximizes the tilt angle by the force of the spring 31, and the valve plate 45 is held in the position by the force of the spring 51 as illustrated in the second diagram, and the suction port 47 and the discharge port 48.
The protrusions 41 and 42 inserted in the above are not in contact with the starting ends of the ports 47 and 48. In this state, when the drive shaft 23 is rotationally driven to rotate the cylinder block 25, the piston 2
6 reciprocally slides while maximizing the sliding amount in the axial direction,
The pump chambers 46 are alternately communicated with the suction ports 47 and the discharge ports 48, the liquid in the suction passage 36 is sucked into the pump chambers 46 via the suction ports 39 and 47, and the liquid sucked into the pump chambers 46. Is discharged from the discharge flow path 37 through the discharge port 48 and the discharge port 40 to obtain the maximum discharge liquid amount. At this time, the pre-expansion and pre-compression action of the liquid is obtained by the notch groove 52 continuously provided at the start end of the suction port 47 and the notch groove 53 continuously provided at the start end of the discharge port 48, so that the rapid pressure in the pump chamber 46 is increased. Control fluctuations and reduce pump noise. In addition, between the intake port 47 and the discharge port 48, which are blocked by the insertion of the protrusions 41 and 42,
A suction port 39 and a discharge port 40 of the valve plate 38, which overlap with the valve plate 45, communicate with each other. When the discharge pressure rises to the set pressure of the pressure control valve 35A, the working chamber 35
The operating piston 33 causes the spring 3 to move due to the pressure liquid introduced into the
By sliding to the left in the first illustration in the first direction against a force, the tilt angle of the swash plate 30 is minimized, and the piston 26 minimizes the amount of sliding in the axial direction to obtain the minimum discharge liquid amount.

In the state where the discharge liquid amount is the minimum, the piston 49 presses the valve plate 45 against the force of the spring 51 by the pressure liquid introduced into the working chamber 50 of the piston 49, and the valve plate 45 moves to the right of the second illustrated state. It rotates and stops at the position where the starting ends of the ports 47, 48 contact the protrusions 41, 42. As a result, the starting ends of the protrusions 41, 42 become the starting ends of the ports 47, 48, and the starting ends of the ports 47, 48 recede. Further, the cutout grooves 52, 53 form the grooves 43, 4 of the protrusions 41, 42.
4 and the length thereof is increased to increase the effects of pre-expansion and pre-compression, and when the suction port 47 is in communication and the discharge port 4 is different from the discharge pressure below the set pressure of the pressure control valve 35A.
A sudden pressure fluctuation in the pump chamber 46, which has a large pressure difference from that during eight communication, is suppressed to reduce pump noise. From this state, when the discharge pressure decreases and becomes equal to or lower than the set pressure of the pressure control valve 35A, the swash plate 30 returns to the original position in the first illustrated state and the maximum discharge liquid amount is obtained. The valve plate 45 returns to the original position in the second illustrated state.

With such an operation, the pressure control valve 35 that maximizes the discharge liquid amount
A cutout groove 52 for pre-expansion and a cutout for pre-compression that suppresses sudden pressure fluctuations in the pump chamber 46 that alternately communicates with the suction port 47 and the discharge port 48 when the discharge pressure is equal to or lower than the set pressure of A. The groove 53 is connected to the grooves 43 and 44 of the protrusions 41 and 42 by the rotation of the valve plate 45 to increase the length thereof when the discharge pressure is the set pressure of the pressure control valve 35A that minimizes the discharge liquid amount. This increases the effects of pre-expansion and pre-compression, and suppresses a rapid pressure fluctuation in the pump chamber 46, which has a large pressure difference between the communication of the suction port 47 and the communication of the discharge port 48 compared to when the discharge pressure is equal to or lower than the set pressure. Therefore, it is possible to suppress a rapid pressure fluctuation in the pump chamber 46 regardless of the maximum and minimum of the discharged liquid amount, and it is possible to favorably reduce the pump noise.

Further, since the protrusions 41 and 42 of the valve plate 38 are inserted into the intake port 47 and the discharge port 48 of the valve body 45, the valve plate 4
5 can be supported by the projections 41, 42, without the need to specifically support both valve plates 38, 45.

Although the variable displacement swash plate type piston pump is used in one embodiment, a variable displacement vane pump may be used, and the valve plate 38 is fixed and the valve plate 45 is rotatably supported, but it may be reversed.

[Effect of device]

As described above, according to the present invention, when the discharge pressure reaches the set pressure and the discharge liquid amount is reduced to the minimum, the suction port and the discharge port at the start ends of the one valve plate communicating with the pump chamber of the rotating body are connected to each other. The actuator relatively rotates the two valve plates until the protrusion provided on the other valve plate comes into contact, whereby the starting end of each port retreats toward the terminal end of the protrusion, and the notch groove forms the protrusion. Since it is connected to the groove of No. 2 and has a long length, favorable pre-expansion and pre-compression effects are obtained and noise is reduced, so that pump noise can be satisfactorily reduced regardless of the maximum and minimum discharge liquid amounts.

Further, since the protrusion portion of the other valve plate is inserted into the intake port and the discharge port of one valve plate, it is possible to support the other by supporting one of the at least two valve plates.
This has the effect that both valve plates can be performed without special support.

[Brief description of drawings]

1 to 3 show an embodiment of the present invention.
FIG. 1 is a vertical sectional view of a variable displacement liquid pump, FIG. 2 is an enlarged sectional view taken along line II-II in FIG. 1, which is a partial circuit diagram, and FIG. 3 is line III in FIG. -Cross-sectional view along line III
FIG. 5 is a vertical sectional view of a variable displacement type liquid pump showing a conventional example of the present invention, and FIG. 5 is an enlarged sectional view taken along line IV-IV of FIG. 20 ... Main body, 25 ... Cylinder block, 30 ... Swash plate, 36 ... Suction flow path, 37 ... Discharge flow path, 38, 45
...... Valve plate, 39, 47 ...... Suction port, 40, 48 ......
Discharge port, 46 ... Pump room.

Claims (1)

[Scope of utility model registration request] 1. A semi-arcuate suction port 39, 47 and a discharge port 40 communicating with the liquid suction passage 36 and the discharge passage 37 in a main body 20 in which a liquid suction passage 36 and a discharge passage 37 are formed. Two valve plates 38 and 45 penetrating through the valve plates 48 and 48 are provided so as to be rotatable relative to each other, and the rotary body 25 slidably contacting one of the valve plates 38 and 45 is rotatably supported in the main body. However, the rotary body 25 is driven to rotate by rotating the one valve plate 45.
Is provided with a plurality of pump chambers 46 that alternately communicate with the suction port 47 and the discharge port 48 to suck and discharge the liquid,
The main body 2 includes a pressure control valve 35A for setting the discharge pressure to a set pressure.
0, and based on the operation of the pressure control valve 35A, when the discharge pressure is equal to or lower than the set pressure, the discharge liquid amount is maximized, and
A discharge amount changing member 30 that minimizes the discharge liquid amount when the discharge pressure reaches a set pressure is provided in the main body, and one of the valve plates 45 that is in sliding contact with the rotating body 25 has a suction port 47 on the sliding contact surface with the rotating body 25. To form a notch groove 52 for pre-expansion in a continuous manner at the starting end of the discharge port 48, and to form a notch groove 53 for pre-compression in a continuous manner at the starting end of the discharge port 48 in the other valve plate 38. Is provided so as to project into the ports 47, 48 of the one valve plate 45, and when the discharge pressure reaches the set pressure, the protrusions 41, 42 are inserted into the ports 47, 48 of the one valve plate 45. An actuator 49 for relatively rotating the two valve plates 37, 45 so that the projections 41, 42 are in contact with the start ends of the ports 47, 48 rather than being separated from the start ends of the ports 47, 48.
50, 51 are provided, and the protrusions 41, 42 are connected to the notch grooves 52, 53 continuously provided at the start ends of the valve plates 45 by contacting the start ends of the ports 47, 48 of the one valve plate 45.
A variable displacement type liquid pump in which 3, 44 are formed as depressions on the protruding end surface.