JP2007270630A - Fluid machine and its valve plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid machine capable of being applied to a low viscous fluid without seizure even though a valve plate made of a metallic material is used. <P>SOLUTION: A tapered section 21 is arranged on a contact surface 20 of a seal land 18 of the valve plate 9 of a swash plate type axial piston pump. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a swash plate pump that pumps a fluid such as water or a fluid machine that is used as a swash plate motor driven by a fluid such as water.

  As a prior art fluid machine, a swash plate type or a swash shaft type axial piston pump is known, and a cross-sectional view showing a configuration of a swash plate type axial piston pump as an example is shown in FIG. .

  FIG. 8 is an enlarged view of the sliding surfaces of the cylinder block 105 and the valve plate (port plate) 109 of the conventional swash plate type axial piston pump. The pressing force from the cylinder block 105 is the product of the hydraulic pressure P1 and the diameter D of the cylinder 105. On the other hand, the hydraulic pressure P1 directly acts as a reaction force at the high pressure port 117. A reaction force is generated from the pressure PA due to the leakage fluid from the high pressure port 117 at a portion between the formation portion of the high pressure port 117 and the inner peripheral edge 118A of the seal land 118, and the outer peripheral edge of the seal land 118 of the high pressure port 117. A reaction force consisting of the pressure PB is also generated between 118B and the leaked fluid.

  Conventionally, when an axial piston pump is used as a hydraulic pump, a low-viscosity fluid such as water tends to leak from the sliding portion due to the nature of the fluid, and in particular, a cylinder block 105 and a valve on which high pressure acts. Leakage is likely to occur at the metal-to-metal contact surface with the plate 109. For this reason, the cylinder block 105 and the valve plate 109 need to be pressed firmly to reduce the gap. However, there is a problem in that the cylinder block 105 hits one side against the valve plate 109 by being pushed strongly, and the sliding surface is likely to be seized.

  Therefore, a valve plate 109 using a synthetic resin material on the sliding surface of the valve plate 109 has been developed. According to such a configuration, the cylinder block 105 and the valve plate 109 are well-fitted, the distance between the two can be reduced, fluid leakage can be prevented, and the contact surface is rubbed between the metal and the resin. As a result, seizure can also be prevented. (See Patent Document 1)

JP-A-9-209918 (paragraphs [0009] to [0015], FIG. 3)

  However, the valve plate to which the synthetic resin material is affixed is expensive. In particular, in order to popularize the axial piston pump as a hydraulic pump, it is necessary to use an inexpensive metal material as the valve plate material. However, even when a valve plate made of a metal material is used, as shown in FIG. 9, the difference between the hydraulic pressure P1 inside the seal land 118, that is, the high pressure port side 117, and the hydraulic pressure P2 outside the seal land 118 is obtained. The seal land 118 is deformed toward the outside where the hydraulic pressure is low (two-dot broken line of the seal land). Due to the deformation of the seal land, the hydraulic pressure distribution is lowered (the two-dot broken line in the graph), and the cylinder and the valve plate come into contact with each other, causing seizure. Further, there is a problem that the coating on the surface of the valve plate is peeled off.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a fluid machine that can be applied to a low-viscosity fluid without seizing even when a valve plate made of a metal material is used.

In order to solve the above problems, the fluid machine of the present invention employs the following means.
That is, the first embodiment according to the present invention includes a plurality of cylinder blocks that rotate about a rotation axis together with a rotation shaft, a piston that reciprocates inside the cylinder block, and an end portion of the piston that rotates about the axis. And a valve plate having a port through which a fluid discharged from the cylinder block or sucked into the cylinder block flows in and out, and the valve plate is in contact with the cylinder block. Thus, the fluid machine is provided with a seal land for preventing fluid leakage, and the fluid machine is characterized in that a defective portion is provided on a contact surface of the seal land with the cylinder block.

  According to such a configuration, even if the seal land is deformed by providing a deficient portion on the contact surface of the seal land with the cylinder block, the reaction force can be stably formed by preventing a decrease in the pressure of the leaking fluid. Can do. Therefore, seizure can be prevented by hitting the cylinder block.

  According to a second aspect of the present invention, there is provided the fluid machine according to the first aspect, wherein the missing portion is a stepped portion at an edge on the port side of the contact surface.

  A step can be provided on the port side edge of the contact surface of the seal land with the cylinder block, and even if the seal land is deformed, the pressure of the leaked fluid is prevented from decreasing and the reaction force is stably formed. can do. Therefore, seizure can be prevented by hitting the cylinder block.

  A third aspect according to the present invention is the fluid machine according to the first aspect, wherein the missing part is a tapered part in which a part of the contact surface faces the port.

  A taper portion can be provided at the port side edge of the contact surface of the seal land with the cylinder block. Even if the seal land is deformed, the contact surface of the seal land and the cylinder block is kept parallel, and the contact surface is widened. Can keep. Therefore, it is possible to prevent a decrease in the pressure of the leaking fluid and to stably form the reaction force, and to prevent seizure of the cylinder block per piece.

  According to a fourth aspect of the present invention, in the second aspect or the third aspect, the defect portion is provided in a part of a circumferential direction of the port side edge of the contact surface. The fluid machine is configured.

  According to such a configuration, the width of the seal land can be kept wide by providing a missing portion in the circumferential direction part of the edge of the seal land on the port side, the seal property of the seal land is maintained, and the cylinder block and The contact surface pressure can be stabilized. Moreover, the fall of the pressure of the leakage fluid can be suppressed. A plurality of the missing portions may be provided on the seal land. Even when the seal land is deformed, the reaction force can be stably formed while maintaining the pressure distribution of the leaking fluid. Therefore, seizure can be prevented by hitting the cylinder block.

  According to a fifth aspect of the present invention, the fluid machine according to the first aspect is characterized in that the defect portion is a groove portion of the contact surface.

  The groove portion can be formed in an arc shape, a dot shape, a linear shape, a zigzag shape, or the like, and a plurality of groove portions may be provided on the seal land. The groove portion can hold the leaking fluid if it communicates with the port, but can hold the leaking liquid from the gap between the seal land and the cylinder block even if it does not communicate. According to such a configuration, the groove portion is provided on the contact surface of the seal land, so that the leaked liquid can be held between the seal land and the cylinder block, and the pressure drop of the leaked fluid can be suppressed. Even if the seal land is deformed, the pressure distribution of the leaked fluid can be maintained, the reaction force can be stably formed, and the contact surface pressure with the cylinder block can be stabilized. Therefore, seizure can be prevented by hitting the cylinder block.

  According to a sixth aspect of the present invention, there is provided a suction port and a discharge port provided on a circumference, a seal land formed around at least one of the suction port and the discharge port, and the seal A valve plate for a fluid machine is provided, wherein a defect portion is provided at an edge on the port side of the contact surface of the land.

  According to such a configuration, by providing a defective portion at the port side edge of the contact surface of the seal land that contacts the cylinder block, even if the seal land is deformed, a decrease in the pressure of the leaked fluid is prevented and Force can be formed stably. Therefore, if the valve plate according to the present invention is used, even if an inexpensive metal valve plate is used, it is possible to manufacture a fluid machine that prevents seizure of the cylinder block per piece.

  The pressure distribution of the leaked fluid is maintained and the reaction force is prevented from being lowered while suppressing the leakage of the fluid from the seal discharge land from the port portion for discharging and sucking the fluid. Therefore, it is possible to prevent the cylinder block and the valve plate from coming into contact with each other and to prevent seizure. If an axial piston pump is configured by applying the present invention, it is possible to provide a pump that can be applied to a low-viscosity fluid even if an inexpensive metal valve plate is used. The present invention is suitable for water which is a low viscosity fluid.

Embodiments according to the present invention will be described below with reference to the drawings.
[First embodiment]
Hereinafter, in the first embodiment of the present invention, an axial piston pump to which the present invention is applied will be described first, and then a valve plate will be described.

  FIG. 7 is a cross-sectional view showing a configuration of a swash plate type axial piston pump which is an example of an axial piston pump (fluid machine). An end plate 2 and a gradle 3 are provided at both ends of the casing 1, respectively. A rotating shaft 4, a cylinder block 5 attached to the rotating shaft, a piston 6 that reciprocates in the cylinder block 5, and a swash plate 8. A piston shoe 7 for fixing the piston, a valve block 9 sandwiched between the cylinder block 5 and the end plate 2 are housed.

  The end plate 2 is mounted on one end of the casing 1 and the gradle 3 is mounted on the other end of the casing 1, and the rotating shaft 4 is rotatably supported by bearings 11 provided individually in the center. Yes. The end plate 2 is provided with a suction port 12 and a discharge port 13 that form a water inlet / outlet of the working fluid. A space surrounded by the casing 1, the end plate 2, and the grade 3 is used as a working fluid chamber 15.

  One end of the rotating shaft 4 passes through the grade 3 and is connected to a driving device such as a motor or a prime mover. The plurality of pistons 6 are inserted so as to be slidable in the metal cylinder block 5, and are attached so as to be splined to the rotating shaft 4 and rotated together with the rotating shaft 4 in the working fluid chamber 15. It has been. The swash plate 8 is supported by the gradle 3 and is built in the working fluid chamber 15 so as to obliquely intersect the axis of the rotating shaft 4. The swash plate 8 has an annular thrust plate 14. It is attached. The piston plate 7 of each piston 6 is slidably attached to the thrust plate 14.

  The valve plate 9 is fixed to the end plate 2, sandwiched between the end plate 2 and the cylinder block 5, and slides relative to the cylinder block 5. The valve plate 9 has a low pressure port 16 communicating with the suction port 12 and a high pressure port 17 communicating with the discharge port 13. The valve plate 9 is a disc having substantially the same diameter as the outer diameter of the working fluid chamber 15. The valve plate 9 is fixed to the end plate 2 with the low pressure port 16 continuing to the opening on the working fluid chamber 15 side of the suction port 12 and the high pressure port 17 continuing to the opening on the working fluid chamber 15 side of the discharge port 13. Has been.

  In the swash plate type axial piston pump having such a configuration, when the rotary shaft 4 is driven, the piston shoe 7 is moved against the thrust plate 14 of the swash plate 8 as the cylinder block 5 is rotated together with the shaft 4. The cylinder block 5 slides on the valve plate 9.

  Therefore, as the rotary shaft 4 rotates, the piston 6 reciprocates in the axial direction according to the inclination angle of the swash plate 8. When the distance between the cylinder 5 and the piston 6 increases, water as a working fluid is sucked into the cylinder block 5 from the suction port 12 through the low pressure port 16 of the valve plate 9. When the interval between the cylinder 5 and the piston 6 is narrowed, it is discharged as high-pressure water from the discharge port 13 through the high-pressure port 17 of the valve plate 9.

  FIG. 1A shows a plan view of the valve plate 9. The valve plate 9 is provided with a rotation shaft hole 19 through which the rotation shaft 4 passes in the center, and a low pressure port 16 and a high pressure port 17 are provided through the valve plate 9 on concentric circles. The seal land 18 is provided so as to protrude in the plate pressure direction of the valve plate 9 so as to surround the low pressure port 16 and the high pressure port 17. The valve plate 9 can be manufactured at a low cost by using a metal material, but is not necessarily limited to a metal material, and a resin material may be used.

  The valve plate 9 is fixed to the end plate 2 with the low pressure port 16 continuing to the opening on the working fluid chamber 15 side in the suction port 12 and the high pressure port 17 continuing to the opening on the working fluid chamber 15 side in the discharge port 13. ing. In addition, the low pressure port 16 and the high pressure port 17 communicate with the inlet / outlet of each cylinder chamber as the cylinder block 5 rotates.

  FIG. 1B shows a cross-sectional view of the valve plate 9 taken along line AA in FIG. A seal land 18 is provided on the surface of the valve plate 9 that contacts the cylinder block 5. The seal land 18 functions as a seal surface that suppresses leakage of the working fluid from between the valve plate 9 and the cylinder block 5 that slides on the valve plate 9. The height of the seal lands 18 provided on the inner diameter side and the outer shape side when viewed from the high pressure port 17 is set to the same height, and the contact surface 20 is flat.

A tapered portion 21 is formed on the edge of the contact surface 20 of the seal land 18 on the high pressure port 17 side. Similarly, a seal land 18 is provided on the low-pressure port 16 side, and a tapered portion 21 is formed at the edge on the low-pressure port 16 side. The angle α of the tapered portion 21 is preferably about 10 ⁻⁵ rad to 10 ⁻³ rad with respect to the contact surface. This is because a decrease in the liquid pressure of the leaked liquid can be prevented while maintaining the sealing performance.

  Liquid leakage in the swash plate type axial piston pump is particularly likely to occur on the contact (sliding) surface between the valve plate 9 and the cylinder block 5 on which high pressure acts. The cylinder block 5 is pressed against the valve plate 9 to reduce the gap at the contact surface 20 and prevent fluid leakage.

  FIG. 2 shows the hydraulic pressure distribution of the leaking fluid in FIG. A reaction force against the cylinder block 5 is formed by leakage of liquid from the gap between the cylinder block 5 and the valve plate 9. Assuming that the hydraulic pressure from the cylinder block 5 is p based on the hydraulic pressure outside the seal land 18, the hydraulic pressure of the high-pressure port 17 is p, and the hydraulic pressure at the tapered portion 21 provided on the contact surface 20 is also p. is there. The liquid pressure of the leaked liquid gradually decreases to 0 on the contact surface 20 toward the outside of the high pressure port 17.

  FIG. 3 shows a comparison of the pressure distribution of the leaked liquid between the conventional valve plate 109 and the valve plate 9 according to this embodiment. FIG. 3A shows the pressure distribution of the leaked liquid in the conventional seal land 118. FIG. 3B shows the pressure distribution of the leaked liquid in the seal land 18 having the tapered portion 21 of the present embodiment. The pressure distribution before deformation of the seal land is indicated by a dotted line, and the pressure distribution after deformation is indicated by a solid line. When the conventional seal land 118 is deformed to the outer peripheral side of the valve plate 9, the inner peripheral contact surface of the seal land 118 hits the cylinder block 105, the pressure of the leaked liquid is reduced, and the contact surface pressure is extremely increased. On the other hand, when the seal land 18 according to the present embodiment is deformed to the outer peripheral side of the valve plate 9, the contact surface of the tapered portion 21 is maintained in a state close to parallel to the cylinder block 5, so that the pressure of the leaked liquid is constant A portion to be maintained can be secured, and the contact surface pressure does not increase excessively. Therefore, the sealing performance of the gap between the cylinder block 5 and the valve plate 9 can be maintained, and seizure can be prevented when the cylinder block 5 and the valve plate 9 come into contact with each other.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 4 shows a sectional view of the valve plate on the high pressure port side.
A seal land 18 is formed on the valve plate 9 so as to surround the high-pressure port 17. A step portion 22 is provided in the seal land 18, and the hydraulic pressure of the high pressure port 17 acts on the cylinder block 5 as it is in the step portion 22. The contact surface 20 of the seal land 18 maintains the sealing performance of the seal land 18 between the seal land 18 and the cylinder block 5, and prevents one-side contact. The step of the step portion 22 is preferably several micrometers to several tens of micrometers. The seal land 18 of this embodiment can be formed not only on the high pressure port 17 side but also on the low pressure port 16 side.

[Third embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 5A shows an enlarged view of the seal land 18 on the high-pressure port 17 side. FIG. 5B is a BB cross section of the seal land 18 of FIG.
A seal land 18 is formed on the valve plate 9 so as to surround the high-pressure port 17. A plurality of tapered portions 23 are provided at predetermined intervals in a part of the edge of the seal land 18 on the high-pressure port 17 side in the circumferential direction. Further, a step portion may be provided instead of the taper portion 23. In the taper portion 23, the hydraulic pressure of the high pressure port 17 acts on the cylinder block 5 as it is, as in the first embodiment. The contact surface 20 of the seal land 18 maintains the seal property of the seal land between the seal land 18 and the cylinder block 5, and prevents contact with each other. The seal land 18 of this embodiment can be formed in the same shape not only on the high pressure port 17 side but also on the low pressure port 16 side.

[Fourth embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 6A shows an enlarged view of the seal land 18 on the high pressure port 17 side. FIG. 6B is a CC cross section of the seal land 18 of FIG.
A seal land 18 is formed on the valve plate 9 so as to surround the high-pressure port 17. A plurality of grooves 24 are formed in an arc shape on the contact surface of the seal land 18. Since the groove portion 24 communicates with the high-pressure port 17, it is possible to hold the liquid and keep the liquid pressure the same as the high-pressure port 17 side. Since the liquid pressure of the leaked liquid in the groove 24 acts on the cylinder block 5 as it is, it is possible to prevent seizure of the cylinder block 5 per piece.

  Even when the groove portion 24 is not in communication with the high-pressure port 17, the groove portion 24 can hold the leaked liquid that has penetrated into the gap between the cylinder block 5 and the seal land 18 to maintain the hydraulic pressure. Therefore, the groove portion 24 is not limited to the arc shape, and may be a dot shape, a linear shape, or a zigzag shape.

  The pressure distribution to the cylinder block 5 of the leaked liquid of the seal land 18 shown in FIG. The contact surface 20 </ b> A on the high pressure port 17 side is deformed by the influence of the hydraulic pressure in the radial direction of the high pressure port 17. The pressure distribution also changes, and a pressure drop is observed at the contact surface 20A. However, since the groove portion 17 holds the leaked liquid, the liquid pressure again becomes the same as the liquid pressure p of the high pressure port portion. Therefore, since the liquid pressure of the leaked liquid can be kept high as the entire contact surface of the seal land 18, the contact surfaces 20 </ b> A and 20 </ b> B of the seal land 18 are sealed with the cylinder block 5. Can be maintained, and can be prevented from hitting. The seal land 18 of this embodiment can be formed in the same shape not only on the high pressure port 17 side but also on the low pressure port 16 side.

It is a figure which shows the valve plate which concerns on 1st embodiment of this invention, (a) is a top view of a valve plate, (b) is sectional drawing by the side of the high voltage | pressure port of a valve plate. It is a figure which shows distribution of the hydraulic pressure in the seal land which has a taper part of 1st embodiment of this invention. It is the figure which compared the hydraulic pressure distribution in the seal land of this invention, (a) is the hydraulic pressure distribution in the conventional seal land, (b) is the hydraulic pressure in the seal land which concerns on 1st embodiment of this invention. It is a figure which shows distribution. It is sectional drawing which shows the shape of the seal land which has the level | step-difference part of 2nd embodiment of this invention. It is a figure which shows the valve plate which concerns on 3rd embodiment of this invention, (a) is a top view of a valve plate, (b) is sectional drawing by the side of the high voltage | pressure port of a valve plate. It is a figure which shows the valve plate which concerns on 4th embodiment of this invention, (a) is a top view of a valve plate, (b) is a figure which shows sectional drawing and hydraulic pressure distribution by the side of the high pressure port of a valve plate. . It is sectional drawing which shows the structure of the swash plate type axial piston pump which is an example of an axial piston pump. It is sectional drawing to which the contact site | part of the seal land and cylinder pump in the conventional valve plate was expanded. It is a figure which shows the shape change and pressure distribution change of the seal land in the conventional valve plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Casing 2 End plate 3 Gradle 4 Rotating shaft 5 Cylinder block 6 Piston 7 Piston shoe 8 Swash plate 9 Valve plate 11 Bearing 12 Inlet 13 Outlet 14 Thrust plate 15 Working fluid chamber 16 Low pressure port 17 High pressure port 18 Seal land 19 Rotating shaft hole 20 Contact surface 21 Tapered portion 22 Stepped portion 23 Tapered portion 24 Groove portion

Claims (6)

A plurality of cylinder blocks rotating around the rotation axis together with the rotation axis;
A piston that reciprocates inside the cylinder block;
A swash plate that holds the end of the piston that rotates about the axis in a sliding state;
A valve plate having a port through which fluid discharged from the cylinder block or sucked into the cylinder block flows in and out,
The valve plate is a fluid machine provided with a seal land that is in contact with the cylinder block and prevents fluid leakage,
A fluid machine, wherein a defect portion is provided on a contact surface of the seal land with the cylinder block.   The fluid machine according to claim 1, wherein the defect portion is a step portion at an edge of the contact surface on the port side.   The fluid machine according to claim 1, wherein the defective portion is a tapered portion in which a part of the contact surface faces the port.   4. The fluid machine according to claim 2, wherein the defect portion is provided in a part of a circumferential direction of an edge on the port side of the contact surface. 5.   The fluid machine according to claim 1, wherein the defect portion is a groove portion of the contact surface.   A suction port and a discharge port provided on a circumference; a seal land formed around at least one of the suction port and the discharge port; and an edge of the contact surface of the seal land on the port side A valve plate for a fluid machine, wherein a deficient portion is provided in the fluid machine.

Images