JP2020076401A - Valve plate and liquid pressure rotating machine - Google Patents

Abstract

To provide a valve plate of a liquid rotating machine which can prevent erosion generated when a connection destination of a piston chamber is switched from a low-pressure port to a high-pressure port, and a liquid pressure rotating machine having the valve plate.SOLUTION: A valve plate 100 of the present invention includes: a high-pressure port 10 and a low-pressure port 20; and at least one of a notch 30 connected to a wall face of the high-pressure port 10 and formed so as to extend toward the low-pressure port 20 and a notch 40 connected to a wall face of the low-pressure port 20 and formed so as to extend toward the high-pressure port. A curved face having a curvature radius within a predefined range is formed at a connection part between the notch and a wall face.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a valve plate provided in a hydraulic rotary machine and a hydraulic rotary machine including the valve plate.

  A swash plate type hydraulic rotary machine consists of a cylinder block, multiple pistons, a swash plate, and a valve plate.The piston contacts the swash plate around the axis of the rotary shaft as the cylinder block rotates. The rotation causes reciprocating motion, and suction and discharge from each piston chamber are performed through the suction port on the low pressure side and the discharge port on the high pressure side of the valve plate. Specifically, fluid is sucked into several piston chambers sequentially through the low pressure port of the valve plate, and at the same time, fluid is discharged from some piston chambers through the high pressure port.

In the swash plate type hydraulic rotary machine with the above configuration, when the connection destination of the piston chamber is switched from the low pressure port to the high pressure port, the opening area where the low pressure port opens to the cylinder port is reduced, so that the fluid is sufficiently supplied to the piston chamber. Since it cannot be supplied, the pressure in the hydraulic chamber defined by the piston and the piston chamber becomes negative pressure, and when the high pressure port and the cylinder port communicate with each other, the liquid flows backward from the high pressure port toward the cylinder port. , Rapid pressure fluctuation and discharge flow rate fluctuation occur in the piston chamber. Then, due to the rapid pressure fluctuation and the discharge flow rate fluctuation, radiation noise on the piston pump surface, pressure pulsation, and cavitation occur, and erosion occurs on the valve plate. FIG. 15 shows a photograph around a notch of a copper alloy valve plate which was eroded by cavitation erosion after a 1000-hour durability test in a conventional hydraulic rotary machine.
Conventionally, in order to suppress the abrupt pressure fluctuations and discharge flow fluctuations, a notch is provided at the end of the low pressure port facing the high pressure port of the valve plate, and / or the end of the high pressure port facing the low pressure port, Further, some solutions have been proposed, such as adding an additional oil guide hole or devising the shape of the notch.

  For example, in Patent Document 1 (JP-A-57-171086), a valve plate (valve plate) is communicated with a high pressure port (high pressure port), and an opening of a piston chamber is opened before a main oil hole or a notch groove. There is disclosed a piston pump having a sub oil guide hole communicating with the piston pump.

  Japanese Unexamined Patent Publication No. 4-276188 discloses a so-called deformed notch having an inner taper surface portion and an outer taper surface portion at the end of the valve plate, and Patent Document 3 (Japanese Unexamined Patent Publication No. 5-240148). Japanese Unexamined Patent Application Publication) discloses a two-stage aperture notch. Patent Document 4 (Japanese Unexamined Patent Application Publication No. 2004-100692) discloses a notch having a shape in which a bottom portion is rounded in a cross section perpendicular to the longitudinal direction of the notch, and Patent Document 5 (Japanese Unexamined Patent Application Publication No. 2005-90333). ) Also discloses a notch having a trapezoidal cross section perpendicular to the longitudinal direction of the notch, or a shape in which R is added to the bottom of the cross section. Further, Patent Document 6 (JP 2012-17711A) discloses a notch in which a cross-sectional shape perpendicular to the extending direction of the notch has a substantially semicircular shape.

  Further, in Patent Document 7 (JP 2010-174690A), a notch that is connected to an end of a high pressure port and extends from the end toward the low pressure port and a tip of the notch is disclosed. There is disclosed a valve plate formed with an opening that is connectable to the.

JP-A-57-171086 JP-A-4-276188 JP-A-5-240148 Japanese Patent Laid-Open No. 2004-100692 JP, 2005-90333, A JP 2012-17711 A JP, 2010-174690, A

However, in the conventional technique described in Patent Document 1, since the auxiliary oil guide hole is arranged so as to start opening from a position before the bottom dead center of the piston in the circumferential direction, leakage of high pressure oil cannot be ignored, and There is a problem that the machining of the auxiliary oil guide hole is complicated.
In addition, in the deformed notch, the notch of the two-stage drawing, the notch having the shape of R at the bottom, the notch having the trapezoidal cross section, and the notch having the substantially semicircular cross section described in Patent Documents 2 to 6, the piston is Although it has the effect of suppressing the negative pressure in the chamber, suppressing the noise of the piston pump and rapid flow rate fluctuations, etc., a high-speed jet flows in at the moment when the notch starts to connect to the hydraulic chamber, causing cavitation. Since the bubbles are generated, air bubbles hit the sliding surfaces of the cylinder block and the valve plate and the inner wall of the cylinder port, and the problem that erosion occurs due to the shock wave when the bubbles are broken cannot be sufficiently solved.
Further, as described in Patent Document 7, even when the tip of the notch is provided with an opening that is connectably open to the piston chamber, it cannot be said that erosion is sufficiently prevented. Since it is necessary to provide the valve plate, there is also a problem that the processing of the valve plate becomes complicated.

A main object of the present invention is to provide a valve plate capable of suppressing the occurrence of cavitation and preventing radiation noise, pressure pulsation, and erosion generated in the valve plate. Moreover, since it is possible to prevent erosion, it is possible to provide a valve plate that can prevent contamination (contamination) in the hydraulic circuit and thus prevent problems such as seizure of the pump.
A second object of the present invention is to provide a hydraulic rotary machine provided with a valve plate capable of suppressing the occurrence of cavitation and preventing the radiation noise, pressure pulsation and erosion generated in the cylinder block. That is.

(1)
The valve plate according to one aspect is a valve plate of a hydraulic rotating machine in which a piston reciprocates, and the valve plate is connected to a high pressure port and a low pressure port alternately connected to the piston chamber and a wall surface of the high pressure port, and A notch formed to extend in the direction of the port and at least one of a notch connected to the wall surface of the low pressure port and formed to extend in the direction of the high pressure port. A curved surface having a radius of curvature in the range is formed. The curved surface is a projecting curved surface.

With the conventional notch, the liquid flow is turbulent and cavitation occurs, and this turbulent flow hits the sliding surface of the cylinder block and erodes, and it is also scattered around and causes erosion in a wide range. There is.
However, in the valve plate according to the above aspect, by forming a curved surface at the connection portion between the notch and the wall surface of the port, the flow of liquid from the port to the notch becomes smooth, cavitation is less likely to occur, and the liquid flows into the cylinder block. Even if it hits the sliding surface of, it does not contain cavitation, so erosion does not occur, and it is possible to prevent erosion of the sliding surface of the cylinder block and valve plate, the inner wall of the valve plate, and the inner wall of the cylinder port. .. That is, as compared with the conventional case where a preventive measure is taken near the location of erosion (downstream side), it is possible to suppress the occurrence of cavitation by forming a curved surface at the inflow location of the notch on the upstream side, This can effectively prevent the occurrence of erosion.
Further, since erosion can be prevented, it is possible to prevent contamination (contamination) in the hydraulic circuit, and thus prevent problems such as seizure of the pump.

(2)
A valve plate according to a second aspect of the present invention is the valve plate according to one aspect, wherein the radius of curvature of the curved surface is 0.5 mm or more and 1/2 or less of the thickness of the valve plate.

  In this case, erosion can be preferably prevented by setting the radius of curvature of the curved surface to 0.5 mm or more over the entire curved surface and to 1/2 or less of the thickness of the valve plate.

(3)
A valve plate according to a third aspect of the present invention is the valve plate according to one aspect, wherein the radius of curvature of the curved surface is 0.5 mm or more and 10 mm or less.

  In this case, erosion can be preferably prevented by setting the radius of curvature of the curved surface to 0.5 mm or more and 10 mm or less over the entire curved surface.

(4)
A valve plate according to a fourth aspect of the present invention is the valve plate according to one aspect, in which the curved surface has a radius of curvature of 3 mm or more and 10 mm or less.

  In this case, erosion can be reliably prevented by setting the radius of curvature of the curved surface to 3 mm or more and 10 mm or less over the entire curved surface.

(5)
A valve plate according to a fifth aspect of the present invention is the valve plate according to the first aspect to the fourth aspect of the present invention, further, a curved surface is formed at a corner portion of the notch that abuts the cylinder block. The curved surface formed at this corner is also a convex curved surface.

  In this case, the flow of the liquid from the corner portion of the notch, which comes into contact with the cylinder block, to the cylinder port also becomes smooth, so that the occurrence of cavitation can be prevented and the erosion that occurs in the valve plate and the cylinder port can be prevented.

(6)
A valve plate according to a sixth aspect of the present invention is a hydraulic rotary machine including the valve plate according to the first to fifth aspects.

  In this case, the hydraulic rotator may have a liquid flow from the high pressure port to the notch, a liquid flow from the low pressure port to the notch, and / or a liquid flow from a corner of the notch that abuts the cylinder block to the cylinder port. Since, and become smooth, it is possible to prevent the occurrence of cavitation at each location and prevent the erosion that occurs in the valve plate and the cylinder port.

It is a typical sectional view showing an example of a hydraulic rotating machine. It is a schematic explanatory view showing an example of a valve plate. It is a partial photograph of a valve plate. It is a schematic perspective view of the high pressure port end part of the valve plate in 1st Embodiment. It is a schematic top view of the high pressure port end part of the valve plate in 1st Embodiment. FIG. 6 is a schematic cross-sectional view taken along the line AA ′ in FIG. 5 of the high pressure port end portion of the valve plate in the first embodiment. It is a schematic explanatory view showing a shape of a connecting portion, a loss coefficient, and a flow aspect when a small diameter pipe is connected in the middle of a large diameter pipe. It is a figure which shows the high pressure port of the valve plate used for fluid analysis, the structure of a notch, and a piston chamber. It is a figure which shows the flow of the liquid by a fluid analysis. It is a graph which shows the relationship between the length of an opening, and the maximum flow velocity. It is a partial photograph near the notch of the valve plate of 1st Embodiment. 4 is a partial photograph of a notch and its periphery after a lapse of 2000 hours in a durability test of a valve plate having a radius of curvature of 5 mm according to the first embodiment. It is a photograph of the cylinder block after 2000 hours of durability test, which was performed using the valve plate having the radius of curvature of 5 mm of the first embodiment. 5 is a partial photograph of a notch and its surroundings after a lapse of 150 hours in a durability test of a valve plate having a radius of curvature of 2 mm according to the first embodiment. 4 is a partial photograph of a notch and its surroundings after a lapse of 200 hours in a durability test of a valve plate having a radius of curvature of 3 mm according to the first embodiment. It is a schematic perspective view of the high pressure port end part of the valve plate in 2nd Embodiment. It is a partial photograph of the notch periphery of the valve plate by a prior art after 1000 hours of durability test.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are designated by the same reference numerals. Further, in the case of the same symbols, their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[First Embodiment]
FIG. 1 is a schematic cross-sectional view of a hydraulic rotary machine 200 including the valve plate 100 of the first embodiment. The hydraulic rotary machine 200 is used for the purpose of pressurizing hydraulic oil supplied to actuators of industrial machines and construction machines, using an electric motor, an engine, or the like as a power source.

(Structure of hydraulic rotary machine 200)
The hydraulic rotary machine 200 includes a rotary shaft 101, a cylinder block 102, a plurality of pistons 103, a plurality of shoes 105, a swash plate 106, and a valve plate 100. The rotary shaft 101 is mounted on a housing 107 via bearings 108 and 109. And is rotatably supported. Plural piston chambers 104 are formed in the cylinder block 102, and the cylinder block 102 is coupled to the rotary shaft 101 and rotates together with the rotary shaft 101. Each piston chamber 104 has one end opening at one end of the cylinder block 102 and the other end opening at the other end of the cylinder block 102 via the cylinder port 110. The piston 103 is inserted into each piston chamber 104 from one end side.

A swash plate 106 is arranged on one end side of the cylinder block 102, and one end portion of the piston 103 is rotatably coupled to the swash plate 106 via a shoe 105. The rotary shaft 101 is rotated in the forward direction to move the cylinder block 102. When rotated, the piston 103 also rotates, and as a result, the piston 103 reciprocates in the piston chamber 104 as the cylinder block 102 rotates.
The liquid in the piston chamber 104 is discharged from the high pressure port 10 of the valve plate 100 through the cylinder port 110 while the piston 103 moves in the direction of being pushed into the piston chamber 104 (left direction in FIG. 1), and The liquid is sucked from the low pressure port 20 of the valve plate 100 to the piston chamber 104 via the cylinder port 110 while moving in the direction of being pushed out from the piston chamber 104 (rightward in FIG. 1).
The hydraulic rotary machine 200 rotates the rotary shaft 101 and the cylinder block 102 in opposite directions to replace the high pressure port 10 (discharge port) and the low pressure port 20 (suction port) and discharge liquid in the reverse direction. You can

(Shape of valve plate 100)
2 is a schematic explanatory view showing an example of the valve plate 100 of the present invention, and FIG. 3 is a partial photograph of the valve plate 100 of FIG. 2 and 3, when the rotary shaft 101 is rotated in the forward direction, the port 10 is a high-pressure port, the port 20 is a low-pressure port, the notch 30 is a notch that connects to the high-pressure port 10, and the notch 40 is a connection to the low-pressure port 20. It becomes a notch. 2 and 3, the notch 30 connected to the high pressure port 10 and the notch 40 connected to the low pressure port 20 are drawn, but in the present invention, the notch 30 may be provided only in the high pressure port 10, or the low pressure port. Notches 40 may be provided only in 20, or notches 30, 40 may be provided in both the high pressure port 10 and the low pressure port 20.

(Shape of notches 30 and 40)
4 to 6 respectively show a perspective view of the notch 30 connected to the high pressure port 10, a plan view seen from above, and a cross-sectional view taken along the line AA ′ of FIG. 5.
The notch 30 is a triangular pyramid-shaped groove (hereinafter also referred to as a V notch) extending from the tip portion 35 toward the wall surface 10a of the high pressure port 10, and the notch 30 and the wall surface 10a of the high pressure port 10 have a curved surface at the connection portion 33. Are formed. In FIG. 4, the portion surrounded by white is the connecting portion 33 having a curved surface. In FIGS. 5 and 6, the portion surrounded by the dotted line is the connection portion 33 having a curved surface. The radius of curvature of this curved surface may be different between the surface side (cylinder block side) and the bottom side of the valve plate 100. The curved surface is a projecting curved surface. The curved surface may be composed of a polyhedron that is a set of flat surfaces. Further, the curved surface may be provided at least at the connecting portion 33 between the notch 30 and the wall surface 10a of the high pressure port 10, and the curved surface is provided at the lowest point of the notch 30 (the point where the two connecting portions 33 intersect). It may or may not be provided.
The radius of curvature of the curved surface is preferably 0.5 mm or more, more preferably 1.0 mm or more, and further preferably 3.0 mm or more. The radius of curvature of the curved surface is preferably 1/2 or less of the thickness of the valve plate 100. Although it depends on the size and use of the valve plate 100, the radius of curvature of the curved surface is preferably 10 mm or less, and more preferably 8 mm or less. This is because erosion can be preferably prevented by providing the radius of curvature equal to or larger than the minimum value. Particularly, by setting the radius of curvature to 3.0 mm or more, erosion can be surely prevented. On the other hand, even if a curved surface having a radius of curvature exceeding the maximum value is formed, the effect of forming the curved surface is saturated.
In the present embodiment, the notch 30 has a triangular pyramid-shaped groove in the section from the tip portion 35 to the front of the connection portion 33, but the triangular pyramid-shaped groove has a flattened bottom portion, Alternatively, the bottom of the groove may be rounded.

Regarding the notch 40 connected to the low pressure port 20, a curved surface is formed at the connecting portion between the notch 40 and the wall surface of the low pressure port 20, like the notch 30, and the radius of curvature of the curved surface is preferably 0.5 mm or more, 1.0 mm or more is more preferable, and 3.0 mm or more is further preferable. The radius of curvature of the curved surface is preferably 1/2 or less of the thickness of the valve plate 100. Although it depends on the size and use of the valve plate 100, the curvature radius of the curved surface is preferably 10 mm or less, and more preferably 8 mm or less. The bottom of the notch 40 may have a triangular pyramid shape, a quadrangular pyramid shape, or a rounded bottom of the groove, like the notch 30. The radius of curvature of the curved surface may be different between the notch 30 connected to the high pressure port 10 and the notch 40 connected to the low pressure port 20.
Further, even when the notch 30 and the notch 40 are formed in both the high pressure port 10 and the low pressure port 20, respectively, the shape of the notches 30, 40 is such that the notch 30, 40 is formed in either the high pressure port 10 or the low pressure port 20. The shape of the notch in this case may be the same.
Further, in the illustrated valve plate 100, notches 30 and 40 are provided at one end portions of the ports 10 and 20 facing each other, but the rotary shaft 101 of the hydraulic rotary machine 200 can be moved not only in the forward direction but also in the reverse direction. When rotating and using, also notches may be provided at the other ends of the ports 10 and 20 so that each port 10 and 20 has two notches, and the positions and numbers can be combined as necessary. You may use it.

With the notch in the prior art, the shape of the notch itself has been devised, or an oil guide hole has been provided at the tip of the notch to suppress the noise of the piston pump and rapid fluctuations in the flow rate. Since the flow is turbulent, cavitation occurs, and the turbulent flow hits the sliding surface of the cylinder block and erodes, and is also scattered around, causing erosion in a wide range.
On the other hand, as shown in FIGS. 4 to 6, a curved surface is formed in the connection portion 33 between the notch 30 and the wall surface 10a of the high pressure port 10 (that is, a portion corresponding to the inlet where the liquid in the high pressure port 10 flows into the notch 30). In the case of forming, the flow of the liquid from the high pressure port 10 to the notch 30 becomes smooth, the generation of cavitation is suppressed, and even if the liquid hits the sliding surfaces of the cylinder block 102 and the valve plate 100, the cavitation is not included. Therefore, erosion does not occur, and erosion of the sliding surfaces of the cylinder block 102 and the valve plate 100 and the inner wall of the cylinder port 110 can be prevented. Hereinafter, the change of the liquid flow due to the difference in the shape of the connecting portion 33 between the notch 30 and the high pressure port 10 will be described.

(Principle of the present invention)
When a small-diameter pipe is connected in the middle of a large-diameter pipe through which liquid flows, the liquid flow greatly changes depending on the shape of the connecting portion between the large-diameter pipe and the small-diameter pipe. FIG. 7 shows the loss coefficient according to the shape of the connection portion and the flow observation result.
When the edge of the connection part is sharpened, the loss factor is large (friction heat is generated) and a contraction flow (a phenomenon in which the cross-sectional area of the flow becomes smaller than the cross-sectional area of the pipe) occurs at the inlet, and the flow does not become smooth. On the other hand, when a curved surface is formed at the connecting portion, the loss factor is small and the flow is smooth ("Handbook for Machinery" published by the Japan Society of Mechanical Engineers in 1981, page 499, "Photobook Flow" by Nihon Kikai. See Maruzen ed., Ed., 1984).

  The inventor believes that the difference in the flow of liquid when a small-diameter pipe is connected in the middle of the large-diameter pipe can be applied to the connection portion between the notch 30 and the wall surface 10a of the high-pressure port 10, and the fluid analysis is performed. Was performed (analysis software: SolidWorks FloXpress). FIG. 8 shows the structure of the high pressure port 10, the notch 30, and the piston chamber 104 of the valve plate 100 used for the fluid analysis. The opening 38 in FIG. 8 indicates a portion where the notch 30 and the piston chamber 104 overlap, that is, a portion through which the liquid can flow. The notch 30 is a V notch with an angle of 60 degrees, and the length of the notch 30 is 8 mm. In the analysis, a pressure of 28 MPa is applied to the liquid in the high pressure port 10 to change the length of the opening 38 and change the radius of curvature (R) of the curved surface portion between the side surface of the notch 30 and the side surface of the port 10. Then, the change of the liquid flow and the maximum flow velocity with respect to the change of the radius of curvature was investigated.

FIG. 9 shows the flow of the liquid according to the fluid analysis result when the connection portion between the wall surface 10a of the port 10 and the notch 30 has a sharp edge (no R: no curved surface) and a round edge (R5: radius of curvature 5 mm). Show. From FIG. 9, in the analysis result of the round edge (R5), the liquid flows smoothly over the entire notch 30, but in the case of the sharp edge (without R), the liquid flow is biased to a part of the notch 30. It can be seen that a contraction has occurred. In FIG. 10, which shows the relationship between the shape of the side surface of the notch 30 and the side surface of the port 10 and the maximum flow velocity, the fact that the contraction flow occurs in the case of the sharp edge (without R) is the round edge (R5). In the case of, the maximum flow velocity increases as the length of the opening 38 is increased, whereas in the case of the sharp edge (without R), the length of the opening 38 is once around 6 to 8 mm. It is also inferred from the fact that the maximum flow velocity is decreasing. From these results, it is considered that by forming a curved surface at the connecting portion between the notch 30 and the wall surface 10a of the high pressure port 10, the liquid smoothly flows, cavitation is suppressed from occurring, and erosion can be prevented.
Further, even when a curved surface is formed at the connecting portion between the notch 40 and the wall surface of the low pressure port 20, the liquid from the low pressure port 20 to the cylinder port 110 can be transferred at the timing when the opening area of the low pressure port 20 and the cylinder port 110 decreases. It is considered that the smooth flow suppresses the occurrence of cavitation and prevents erosion.

(Example)
FIG. 11 shows a partial photograph of the vicinity of the notch 30 of the valve plate 100 in which the curved surface is formed in the connection portion 33 between the notch 30 and the wall surface 10a of the high pressure port 10 of the first embodiment. A curved surface having a radius of curvature of 5 mm was formed in the connection portion 33 between the notch 30 and the wall surface 10 a of the high pressure port 10. The material of the valve plate 100 is nitrided steel.
A liquid provided with a valve plate 100 in which a notch 30 having a curved surface is formed in the connection portion 33 with the wall surface 10a of the high pressure port 10 is formed in the high pressure port 10, and a notch 40 having the same shape as the notch 40 is also formed in the low pressure port 20. Durability evaluation was performed using the pressure rotary machine 200. The maximum rotation speed of the hydraulic rotary machine 200 is 1500 rpm, the relief set pressure of the high pressure port 10 is 21.6 MPa, and the hydraulic oil is VG46. Further, during the durability test, the high-pressure port 10 (discharge port) and the low-pressure port 20 (suction port) are exchanged by switching the rotation direction alternately to the forward direction and the reverse direction at intervals of 0.6 seconds, and the liquid is removed. Discharging was performed alternately in the forward and reverse directions.
A photograph around the notches 30 and 40 of the valve plate 100 after 2000 hours is shown in FIG. As can be seen from FIG. 12, the valve plate 100 had no trace of erosion.
FIG. 13 shows a photograph of the surface (copper alloy welded surface) of the cylinder block 102 that comes into contact with the valve plate 100 after 2000 hours have elapsed. There is a slight jet mark on the iron portion in the cylinder port 110, but the erosion is at a level that poses no problem.

In order to investigate in more detail the relationship between the radius of curvature of the curved surface formed in the connection portion 33 between the notch 30 and the wall surface 10a of the high pressure port 10 and the occurrence of cavitation erosion, a curved surface with a radius of curvature of 0.2 mm, 1 mm, 2 mm, and 3 mm is provided. The valve plate 100 was prepared and a durability test was conducted. According to the result of the durability test, in the valve plate 100 having a radius of curvature of 0.2 mm, 1 mm, and 2 mm, erosion traces are recognized in the durability test in less than 200 hours, but in the valve plate 100 having a radius of curvature of 3 mm, erosion is completely generated. I was not able to admit.
FIG. 14 shows a partial photograph around the notch of the valve plate 100 having a radius of curvature of 2 mm after a durability test of 150 hours. Further, FIG. 15 shows a partial photograph around the notches 30 and 40 of the valve plate 100 having a radius of curvature of 3 mm after 200 hours of the durability test. When FIG. 14 and FIG. 15 are compared, when the radius of curvature is 2 mm, a trace of erosion is recognized after 150 hours. On the other hand, when the radius of curvature was 3 mm, no trace of erosion was observed even after 200 hours had elapsed. Therefore, in the valve plate 100 of the first embodiment, there is a critical point between the radius of curvature of 2 mm and 3 mm to determine whether or not the liquid flows smoothly. By setting the radius of curvature to 3 mm or more, the liquid is smoothed. It is considered that the erosion can be surely prevented by suppressing the occurrence of cavitation.

[Second Embodiment]
In the valve plate 100 of the second embodiment, a curved surface is formed in the connection portion 33 between the notches 30 and 40 and the wall surface of the high pressure port 10 and / or the low pressure port 20, and further, shown in FIG. In this manner, the valve plate 100 has a curved surface formed also at the corner portion 34 (the portion where the inner wall surface of the notch 30 and the surface of the valve plate 100 intersect) of the notch 30 that comes into contact with the cylinder block 102. The curved surface formed on the corner portion 34 is also a protruding curved surface. The curved surface may be composed of a polyhedron that is a set of flat surfaces.
The liquid flowing back from the high-pressure port 10 to the notch 30 further flows into the piston chamber 104 via the cylinder port 110. In the case of the conventional valve plate 100 having no curved surface at the corner contacting the cylinder block 102 of the notch 30, The interface between the notch 30 and the cylinder port 110 has a shape similar to the sharp edge (without R) in FIG. 7, and a contraction flow occurs. On the other hand, in the case of the valve plate 100 in which a curved surface is formed at the corner of the notch 30 that comes into contact with the cylinder block 102, the valve plate 100 has a shape similar to the round edge (with R) of FIG. 7, and the liquid flows smoothly, No contraction occurs. Then, as the liquid flows smoothly, in the valve plate 100 having a curved surface at the corner of the notch 30 that contacts the cylinder block 102, the occurrence of cavitation around the corner of the notch 30 that contacts the cylinder block 102 is suppressed, Erosion can be prevented.
The radius of curvature of the curved surface in the second embodiment is preferably 0.5 mm or more and 10 mm or less.
Also with respect to the notch 40 connected to the end portion of the low pressure port 20, by forming a curved surface at a corner portion of the notch 40 that abuts the cylinder block 102, it is possible to suppress cavitation and prevent erosion.

  As described above, by forming a curved surface at the connection between the notches 30 and 40 and the wall surface of the high pressure port 10 and / or the low pressure port 20, the occurrence of cavitation is suppressed and the cavitation is generated in the valve plate 100 and the cylinder block 102. Erosion can be prevented.

  In the present invention, the valve plate 100 corresponds to a “valve plate”, the high pressure port 10 corresponds to a “high pressure port”, the low pressure port 20 corresponds to a “low pressure port”, and the notches 30 and 40 correspond to a “notch”. The connecting portion 33 corresponds to the "connecting portion", the piston chamber 104 corresponds to the "piston chamber", the piston 103 corresponds to the "piston", the cylinder block 102 corresponds to the "cylinder block", and the hydraulic pressure is The rotary machine 200 corresponds to a “hydraulic rotary machine”.

  Although the preferred embodiment of the present invention is as described above, the present invention is not limited thereto. It will be appreciated that various other embodiments may be made without departing from the spirit and scope of the invention. Furthermore, in the present embodiment, the actions and effects of the configuration of the present invention are described, but these actions and effects are merely examples and do not limit the present invention.

10 High Pressure Port 20 Low Pressure Port 30 Notch Connected to High Pressure Port 33 Connection Part 40 Notch Connected to Low Pressure Port 100 Valve Plate 102 Cylinder Block 103 Piston 104 Piston Chamber 110 Cylinder Port 200 Hydraulic Rotary Machine

Claims (6)

A valve plate of a hydraulic rotary machine in which a piston reciprocates,
The valve plate is
A high pressure port and a low pressure port alternately connected to the piston chamber,
At least one of a notch that is connected to the wall surface of the high pressure port and extends in the direction of the low pressure port, and a notch that is connected to the wall surface of the low pressure port and that extends in the direction of the high pressure port,
A valve plate in which a curved surface having a radius of curvature within a predetermined range is formed at a connection portion between the notch and the wall surface.   The valve plate according to claim 1, wherein a radius of curvature of the curved surface is 0.5 mm or more and 1/2 or less of a thickness of the valve plate.   The valve plate according to claim 1, wherein a radius of curvature of the curved surface is 0.5 mm or more and 10 mm or less.   The valve plate according to claim 1, wherein the radius of curvature of the curved surface is 3 mm or more and 10 mm or less.   The valve plate according to any one of claims 1 to 4, wherein a curved surface is formed at a corner portion of the notch that abuts the cylinder block. A hydraulic rotary machine comprising the valve plate according to claim 1.