Fluid machine and construction machine

Abstract

The present application relates to a fluid machine and a construction machine. A main pump of an embodiment is provided with: a cylinder; a piston housed in a cylinder chamber in a slidingly movable manner; a housing that houses the cylinder; and a valve plate (19) disposed between the cylinder and the housing. The valve plate (19) has: a suction port; a discharge port formed on the side opposite the suction port via a pair of switching lands formed on a first face (41a); a piston housing recess (49) that houses the piston; and a valve plate communication hole (51) that communicates the piston housing recess (49) with the switching lands.

Description

TECHNICAL FIELD

[0001] The present application relates to a fluid machine and a construction machine. BACKGROUND

[0002] As a fluid machine, for example, there is a so-called swash plate type hydraulic piston pump (hereinafter, simply referred to as a hydraulic pump) mounted on a construction machine such as a hydraulic excavator. Such a hydraulic pump has, for example, a shaft rotatably supported in a pump case, a cylinder fixed to an outer peripheral surface of the shaft, and a plurality of pistons. A plurality of cylinder chambers are formed in the cylinder. The pistons are respectively housed in the cylinder chambers in a manner so as to be able to slide along an axial direction of the shaft (hereinafter, simply referred to as an axial direction).

[0003] The hydraulic pump has a swash plate disposed on a first end portion side in the axial direction of the cylinder and a valve plate disposed on a second end portion side opposite to the first end portion. The swash plate restricts the sliding movement of the pistons in the cylinder chambers by end portions of the pistons that are movable on a surface of the swash plate. The swash plate changes a volume of a space formed by the cylinder chambers and the pistons in accordance with an inclination angle with respect to the pump case. In the valve plate, suction ports and discharge ports through which working oil flows are formed at positions corresponding to the plurality of cylinder chambers of the cylinder. The suction ports communicate with a suction passage of the pump case. The discharge ports communicate with a discharge passage of the pump case. In an end surface of the valve plate on the cylinder side, a switching land portion facing the second end portion of the cylinder is formed between the suction ports and the discharge ports.

[0004] Based on such a structure, if the cylinder is rotated around the axis of the shaft, each cylinder chamber revolves around the shaft as a center, and alternately communicates with the suction ports and the discharge ports by the switching land portion of the valve plate. At a timing at which the cylinder chamber communicates with the suction port, the piston slides in the cylinder chamber in a manner so as to increase a volume of the space in the cylinder chamber. Thereby, working oil is sucked from outside the pump case into the cylinder chamber via the suction passage and the suction port (suction process). At a timing at which the cylinder chamber communicates with the discharge port, the piston slides in the cylinder chamber in a manner so as to decrease the volume of the space in the cylinder chamber. Thereby, working oil is discharged from the cylinder chamber to outside the pump case via the discharge port and the discharge passage (discharge process).

[0005] Here, at the timing at which the cylinder chamber communicates with the discharge port, the cylinder chamber is abruptly opened by the discharge port, and thus, it is possible that working oil is inversely injected into the cylinder chamber due to a pressure difference. In such a case, a high-speed fluid (working oil) collides with an inner wall surface of the cylinder chamber, and thus, cavitation (hereinafter, referred to as erosion) occurs. Therefore, a technique of forming a hole that communicates the discharge port of the valve plate with the switching land portion of the valve plate is disclosed (for example, refer to Patent Literature 1). A technique of forming a notch in the switching land portion of the valve plate at a lower dead point position at which the switching is switched from the suction process to the discharge process is disclosed (for example, refer to Patent Literature 2). Either technique suppresses a sharp change in pressure in the cylinder chamber by introducing the pressure of the fluid on the discharge port side into the cylinder chamber.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent Application Publication No. S57-171086

[0009] Patent Document 2: Japanese Patent Application Publication No. 2010-174690 SUMMARY

[0010] Problems to be Solved by the Invention

[0011] However, in the above-described Patent Document 1, there is a possibility that the processing cost of the valve plate increases due to difficulty in easily processing the hole.

[0012] In the above-described Patent Document 2, the pressure of the injection port is branched to the cylinder chamber at a position immediately next to the injection port, and thus there is a possibility that it is difficult to obtain the anticorrosion effect.

[0013] The present application provides a fluid machine and construction machine capable of suppressing the processing cost of a valve plate and obtaining a sufficient anticorrosion effect of a cylinder chamber.

[0014] Solution to the Problem

[0015] A fluid machine of one aspect of the present application includes: a cylinder that forms a cylinder chamber and forms a cylinder body communication hole that communicates the inside and outside of the cylinder chamber; a piston that is housed in the cylinder chamber in a manner that is free to slide and move, the piston performing an injection process that compresses the cylinder chamber and a suction process that expands the cylinder chamber; a housing that houses the cylinder, the housing forming a suction path and an injection path; a valve plate that is disposed between the cylinder and the housing; and a push member that pushes the valve plate toward the cylinder side, the valve plate having: a suction port that communicates the cylinder body communication hole and the suction path; an injection port that is formed on the side opposite the suction port in a manner that a pair of switching lands formed on a first face of the valve plate on the cylinder side are sandwiched therebetween, the injection port communicating the cylinder body communication hole and the injection path; a push member housing recess that is formed on a second face of the valve plate on the side opposite the first face at a position that avoids the suction path and the injection path, the push member housing recess housing the push member; and a valve plate communication hole that communicates the push member housing recess and the switching land.

[0016] Thus, the valve plate communication hole is formed using the push member housing recess, and thus the pressure of the injection port can be branched to the switching land side via the valve plate communication hole. Therefore, the sharp pressure change in the cylinder chamber can be suppressed. Thus, the processing cost of the valve plate can be suppressed, and a sufficient anticorrosion effect of the cylinder chamber can be obtained.

[0017] In the above structure, the valve plate can be formed with a notch extending from the discharge port toward a lower dead center switching land, the valve plate communication hole can be disposed at a position separated from the front end of the notch toward the suction port side, and the front end of the notch can be defined as an end portion on the side opposite the discharge port.

[0018] In the above structure, the valve plate can be formed with a notch extending from the discharge port toward a lower dead center switching land, the valve plate communication hole can be disposed at a position separated from the front end of the notch toward the suction port side, and the front end of the notch can be defined as an end portion on the side opposite the discharge port.

[0019] In the above structure, the push member can be a small piston in a circular plate shape.

[0020] Another technical solution of the present application provides a fluid machine including: a cylinder body formed with a cylinder chamber and a cylinder body communication hole that communicates the inside and outside of the cylinder chamber; a piston housed in the cylinder chamber in a manner that is free to slide, the piston performing a discharge process that compresses the cylinder chamber and a suction process that expands the cylinder chamber; a housing that houses the cylinder body, the housing formed with a suction path and a discharge path; a valve plate disposed between the cylinder body and the housing; and a push member that pushes the valve plate toward the cylinder body side, the valve plate having: a suction port that communicates the cylinder body communication hole and the suction path; a discharge port formed on the side opposite the suction port in a manner that a pair of switching lands formed on a first surface of the valve plate on the cylinder body side sandwich the discharge port, the discharge port communicating the cylinder body communication hole and the discharge path; a push member housing recess formed on a second surface of the valve plate on the side opposite the first surface at a position that avoids the suction port and the discharge port, the push member housing recess housing the push member; a notch extending from the discharge port toward a lower dead center switching land; and a valve plate communication hole disposed at a position separated from the front end of the notch toward the suction port side, the valve plate communication hole communicating the push member housing recess and the switching land, the lower dead center switching land defined as a land of the pair of switching lands disposed at a lower dead center position at which the piston switches from the suction process to the discharge process, and the front end of the notch defined as an end portion on the side opposite the discharge port.

[0021] By being configured like this, the valve plate communication hole is formed using the push member housing recess, so the pressure of the discharge port can be branched to the lower dead point switching land side via the valve plate communication hole. Therefore, fluid can be prevented from being injected backward into the cylinder chamber during the discharge process. Thus, the machining cost of the valve plate can be reduced, and sufficient anticorrosion effects of the cylinder chamber can be obtained.

[0022] The fluid machine according to another aspect of the present application includes: a cylinder that forms a cylinder chamber and forms a cylinder communication hole that communicates the inside and outside of the cylinder chamber; a piston that is housed in the cylinder chamber in a manner that is free to slide, the piston performing a discharge process that compresses the cylinder chamber and a suction process that expands the cylinder chamber; a housing that houses the cylinder, the housing forming a suction path and a discharge path; a valve plate that is disposed between the cylinder and the housing; and a push member that pushes the valve plate toward the cylinder side, the valve plate having: a suction port that communicates the cylinder communication hole and the suction path; a discharge port that is formed on the side opposite the suction port in a manner that sandwiches a pair of switching lands formed on a first face of the valve plate on the cylinder side between the switching lands, the discharge port communicating the cylinder communication hole and the discharge path; a push member housing recess that is formed on a second face of the valve plate on the side opposite the first face at a position that avoids the suction port and the discharge port, the push member housing recess housing the push member; a notch that extends from the discharge port toward a lower dead point switching land; and a valve plate communication hole that is disposed at the front end of the notch, the valve plate communication hole communicating the push member housing recess and the switching land, the lower dead point switching land being defined as the land of the pair of switching lands that is disposed at a lower dead point position at which the piston switches from the suction process to the discharge process, the front end of the notch being defined as the end on the side opposite the discharge port.

[0023] The switching land is formed by grinding the valve plate when the valve plate is finished. At this time, the valve plate communication hole is formed at the front end of the notch, so the distance between the notch and the valve plate communication hole can be prevented from changing due to the amount of grinding. That is, the position of the front end of the notch changes due to the amount of grinding, but the valve plate communication hole is formed at the front end of the notch, so the distance between the notch and the valve plate communication hole can be prevented from changing. Therefore, the effects of the valve plate communication hole can be stabilized regardless of the amount of grinding.

[0024] Another technical solution of the present application provides a construction machine including: a vehicle body; and a fluid machine that sucks and ejects a fluid that is a driving source of the vehicle body, the fluid machine including: a cylinder that forms a cylinder chamber and a cylinder communication hole that communicates the inside and outside of the cylinder chamber; a piston that is housed in the cylinder chamber in a slidable manner, the piston performing an ejecting process that compresses the cylinder chamber and a sucking process that expands the cylinder chamber; a housing that houses the cylinder, the housing forming a sucking path and an ejecting path; a valve plate that is disposed between the cylinder and the housing; and a pushing member that pushes the valve plate toward the cylinder side, the valve plate including: a sucking port that communicates the cylinder communication hole and the sucking path; an ejecting port that is formed on the opposite side of the sucking port in a manner that a pair of switching lands on a first surface of the valve plate on the cylinder side are sandwiched therebetween, the ejecting port communicating the cylinder communication hole and the ejecting path; a pushing member housing recess that is formed on a second surface of the valve plate on the opposite side of the first surface at a position that avoids the sucking port and the ejecting port, the pushing member housing recess housing the pushing member; a notch that extends from the ejecting port toward a lower dead point switching land; and a valve plate communication hole that is disposed at a position that is separated from the sucking port side from a front end of the notch, the valve plate communication hole communicating the pushing member housing recess and the switching land, the lower dead point switching land being defined as a land of the pair of switching lands that is disposed at a lower dead point position at which the piston switches from the sucking process to the ejecting process, and the front end of the notch being defined as an end portion on the opposite side of the ejecting port.

[0025] By being configured in this way, a construction machine that can suppress the processing cost of the valve plate and that can obtain sufficient corrosion prevention effects of the cylinder chamber can be provided.

[0026] Another technical solution of the present application is a construction machine including: a vehicle body; and a fluid machine that sucks and ejects a fluid that is a driving source of the vehicle body, the fluid machine including: a cylinder that forms a cylinder chamber and a cylinder communication hole that communicates the inside and outside of the cylinder chamber; a piston that is housed in the cylinder chamber in a slidable manner, the piston performing an ejecting process that compresses the cylinder chamber and a sucking process that expands the cylinder chamber; a housing that houses the cylinder, the housing forming a sucking path and an ejecting path; a valve plate that is disposed between the cylinder and the housing; and a pushing member that pushes the valve plate toward the cylinder side, the valve plate including: a sucking port that communicates the cylinder communication hole and the sucking path; an ejecting port that is formed on the opposite side of the sucking port in a manner that a pair of switching lands on a first surface of the valve plate on the cylinder side are sandwiched therebetween, the ejecting port communicating the cylinder communication hole and the ejecting path; a pushing member housing recess that is formed at a position of a second surface of the valve plate on the opposite side of the first surface that avoids the sucking port and the ejecting port, the pushing member housing recess housing the pushing member; a notch that extends from the ejecting port toward a lower dead point switching land; and a valve plate communication hole that is disposed at the front end of the notch, the valve plate communication hole communicating the pushing member housing recess and the switching land, the lower dead point switching land being defined as a land of the pair of switching lands that is disposed at a lower dead point position at which the piston switches from the sucking process to the ejecting process, the front end of the notch being defined as an end portion on the opposite side of the ejecting port.

[0027] By being configured as such, a construction machine that can stabilize the effect of the valve plate communication hole regardless of the polishing amount can be provided.

[0028] Effects of the Invention

[0029] The fluid machine and the construction machine described above can suppress the processing cost of the valve plate and can obtain sufficient corrosion prevention effect of the cylinder chamber. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a schematic configuration view of a construction machine in an embodiment of the present application.

[0031] Figure 2 is a configuration view of a pump unit in an embodiment of the present application.

[0032] Figure 3 is a plan view of a first surface side of a valve plate in a first embodiment of the present application.

[0033] Figure 4 is a plan view of a second surface side of a valve plate in a first embodiment of the present application.

[0034] Figure 5 is a sectional view taken along Figure 4 the line A-A of Fig. 1.

[0035] Figure 6 is a sectional view taken along Figure 3 the line B-B of Fig. 1.

[0036] Figure 7 is a sectional view of a main portion of a valve plate in the second embodiment of the present application.

[0037] BRIEF DESCRIPTION OF DRAWINGS

[0038] 1. main pump (fluid machine); 2. main housing (housing); 4. cylinder; 17. cylinder chamber; 18. communication hole (cylinder communication hole); 19, 219. valve plate; 19a. suction port; 19b. discharge port; 21. piston; 41a. first face; 41b. second face; 46. push piston (push member); 47a. lower dead center switching land; 47b. upper dead center switching land; 49. piston housing recess (push member housing recess); 50. notch; 51. valve plate communication hole; 101. swing body (vehicle body); 102. traveling body (vehicle body); 122. first suction passage (suction passage); 123. discharge passage. DETAILED DESCRIPTION

[0039] Next, embodiments of the present application will be described based on the drawings.

[0040] CONSTRUCTION MACHINE

[0041] Figure 1 is a schematic configuration view of the construction machine 100.

[0042] As shown in Figure 1 , the construction machine 100 is, for example, a hydraulic shovel or the like. The construction machine 100 is provided with a swing body (one example of the vehicle body in the claim) 101 and a traveling body (one example of the vehicle body in the claim) 102 provided at a lower portion of the swing body 101. The swing body 101 swings at an upper portion of the traveling body 102. The swing body 101 is provided with a pump unit (one example of the fluid machine in the claim) 110.

[0043] The swing body 101 is provided with: a cab 103 for supporting an operator who rides on the swing body 101; a boom 104 whose one end is linked to the cab 103; a stick 105 whose one end is linked to the other end of the boom 104; and a bucket 106 linked to the other end of the stick 105. The boom 104 swings with respect to the cab 103. The stick 105 swings with respect to the boom 104. The bucket 106 swings with respect to the stick 105.

[0044] The pump unit 110 is provided in the cab 103. Working oil supplied from the pump unit 110 becomes a driving source of the cab 103, the boom 104, the arm 105, and the bucket 106.

[0045] Pump Unit

[0046] Figure 2 is a structure diagram in which a part of the pump unit 110 is cut away.

[0047] The pump unit 110 is a so-called hydraulic pump. The pump unit 110 sucks and ejects working oil. As shown in Figure 2 , the pump unit 110 is provided with a main pump (one example of a fluid machine in the claims) 1 as a fluid machine and a gear pump 111 provided on one side of the main pump 1. Figure 2 Only the main pump 1 is shown in a cross section along an axial direction. In Figure 2 , the scale of each member is appropriately changed for easy understanding of the explanation.

[0048] Main Pump

[0049] The main pump 1 is a so-called swash plate type variable displacement hydraulic pump. The main pump 1 mainly includes a main housing (one example of a housing in the claims) 2, a shaft 3 supported to the main housing 2 so as to be rotatable about a center axis C with respect to the main housing 2, a cylinder block 4 housed in the main housing 2 and fixed to the shaft 3, a swash plate 5 housed in the main housing 2 and provided so as to be tiltable with respect to the main housing 2, a piston 21 provided to the cylinder block 4, a valve plate 19 disposed between the main housing 2 and the cylinder block 4, and a push piston (one example of a pushing member in the claims) 46 provided to the valve plate 19.

[0050] In Figure 2 , the scale of each member is appropriately changed for easy understanding of the explanation. In the following explanation, a direction parallel to the center axis C of the shaft 3 is referred to as an axial direction, a direction of rotation of the shaft 3 is referred to as a circumferential direction, and a radial direction of the shaft 3 is simply referred to as a radial direction.

[0051] The main housing 2 includes a housing main body (one example of a housing in the claims) 9 having an opening portion 9a and a front flange plate 10 that closes the opening portion 9a of the housing main body 9.

[0052] The housing main body 9 includes a bottom wall 119 provided on the side opposite to the opening portion 9a. The bottom wall 119 is a wall portion of the housing main body 9 located on the center axis C of the shaft 3. The cylinder block 4 is disposed on the inner surface 119a side of the bottom wall 119. The gear pump 111 is attached to the outer surface 119b of the bottom wall 119.

[0053] A rotation shaft through-hole 121 through which the shaft 3 penetrates is formed in the bottom wall 119 in a manner penetrating the bottom wall 119 in the plate thickness direction of the bottom wall 119. In the rotation shaft through-hole 121, a bearing 11 that rotatably supports one end side of the shaft 3 is provided at a position close to the inner surface 119a of the bottom wall 119.

[0054] In the bottom wall 119, a first suction passage 122 (one example of the suction passage in the claims) and a discharge passage 123 are formed on both sides in the radial direction across the rotation shaft through-hole 121. The first suction passage 122 forms an opening portion 122a in a first side surface 119c of the bottom wall 119. The opening portion 122a of the first suction passage 122 communicates with a tank not shown. The first suction passage 122 extends in the bottom wall 119 in a manner in which the opening area gradually decreases as it goes from the first side surface 119c toward the rotation shaft through-hole 121.

[0055] An end portion of the first suction passage 122 on the rotation shaft through-hole 121 side forms a first communication passage 124 that communicates the first suction passage 122 with the inner surface 119a of the bottom wall 119. The first communication passage 124 communicates the first suction passage 122 with a suction port 19a of a valve plate 19 described later.

[0056] The end portion of the first suction passage 122 on the rotation shaft through-hole 121 side does not communicate with the rotation shaft through-hole 121. An end portion of the first suction passage 122 on the rotation shaft through-hole 121 side forms a second communication passage 125 that communicates the first suction passage 122 with an outer surface 119b of the bottom wall 119. The second communication passage 125 communicates the first suction passage 122 with a second suction passage 144 of a gear pump 111 described later.

[0057] An O-ring groove 118 is formed in the outer surface 119b of the bottom wall 119 in a manner that surrounds the periphery of the rotation shaft through-hole 121 and the second communication passage 125. An O-ring 117 is installed in the O-ring groove 118. The O-ring 117 ensures the sealing between the main housing 2 and a gear housing 141 of the gear pump 111 described later.

[0058] Based on such a structure, working oil is suctioned from a tank not shown into the first suction passage 122. The working oil suctioned into the first suction passage 122 flows to the first communication passage 124 and the second communication passage 125.

[0059] The discharge passage 123 forms an opening portion 123a in a second side surface 119d of the bottom wall 119 on the side opposite the first side surface 119c across the rotation shaft through-hole 121. The opening portion 123a is connected to the cab 103, the boom 104, the arm 105, and the bucket 106 by means of a control valve not shown and the like. The discharge passage 123 extends in the bottom wall 119 from the second side surface 119d toward the rotation shaft through-hole 121.

[0060] The end portion of the ejection path 123 on the side of the rotation shaft through hole 121 is not communicated with the rotation shaft through hole 121. A third communication path 128 that communicates the ejection path 123 with the inner surface 119a of the bottom wall 119 is formed at the end portion of the ejection path 123 on the side of the rotation shaft through hole 121. The third communication path 128 communicates the ejection path 123 with the ejection port 19b of the valve plate 19 described later.

[0061] A through hole 13 through which the shaft 3 is inserted is formed in the front flange plate 10. A bearing 14 that rotatably supports the other end side of the shaft 3 is provided in the through hole 13. An oil seal 15 is provided in the through hole 13 at a position on the side opposite to the housing main body 9 (the outer side of the front flange plate 10) from the bearing 14. The oil seal 15 prevents the working oil from flowing out from the inside, and prevents the intrusion of foreign matter and the like from between the shaft 3 and the front flange plate 10.

[0062] Two mounting plates 137 are formed integrally with the front flange plate 10. The two mounting plates 137 are disposed on both sides in the radial direction with the shaft 3 interposed therebetween. The mounting plates 137 extend toward the radial direction outer side. The two mounting plates 137 are used to fix the main pump 1 to a driving source such as an engine provided in the rotor body 101.

[0063] The shaft 3 is formed in a stepped shape. The shaft 3 is integrally formed by the shaft main body 131, the first bearing portion 132 that extends from the shaft main body 131 toward the one end side (the side of the bottom wall 119 of the main housing 2) of the shaft 3, the transmission shaft 133 that extends from the first bearing portion 132 toward the side opposite to the shaft main body 131, the second bearing portion 134 that extends from the shaft main body 131 toward the other end side (the side of the front flange plate 10) of the shaft 3, and the connecting shaft 135 that extends from the second bearing portion 134 toward the side opposite to the shaft main body 131.

[0064] The shaft main body 131 is disposed inside the main housing 2. The first spline 131a is formed in the shaft main body 131. The cylinder block 4 is fitted in the first spline 131a. The push member 27 is fitted in the outer peripheral surface of the shaft main body 131 at a position on the side of the second bearing portion 134. The push member 27 is used to push the shoe holding member 29 described later.

[0065] The shaft diameter of the first bearing portion 132 is smaller than the shaft diameter of the shaft main body 131. The first bearing portion 132 is rotatably supported by the bearing 11 of the bottom wall 119.

[0066] The transmission shaft 133 transmits the rotational force of the shaft 3 to the gear pump 111. The shaft diameter of the transmission shaft 133 is smaller than that of the first bearing portion 132. The transmission shaft 133 protrudes to the gear pump 111 side via the bearing 11. The transmission shaft 133 is disposed within the rotation shaft through hole 121 of the bottom wall 119. A cylindrical coupling 136 is fitted to the outer peripheral surface of the transmission shaft 133. The coupling 136 rotates integrally with the transmission shaft 133. The end portion of the coupling 136 on the side opposite to the first bearing portion 132 protrudes to the outside of the bottom wall 119 via the rotation shaft through hole 121. This protruding portion is connected to the gear pump 111.

[0067] The shaft diameter of the second bearing portion 134 is larger than that of the first bearing portion 132. The second bearing portion 134 is rotatably supported by the bearing 14 of the front flange plate 10.

[0068] The coupling shaft 135 is connected to a power source such as an engine, not shown. The shaft diameter of the coupling shaft 135 is smaller than that of the second bearing portion 134. The front end portion of the coupling shaft 135 on the side opposite to the second bearing portion 134 protrudes to the outside of the front flange plate 10 via the bearing 14. A second spline 135a is formed on the front end portion of the coupling shaft 135. The power source such as an engine, not shown, and the shaft 3 are connected by means of this second spline 135a.

[0069] The cylinder body 4, which is fixed to the shaft 3, is formed in a cylindrical shape. A through hole 16 into which the shaft 3 is inserted or pressed is formed in the radial center of the cylinder body 4. A spline 16a is formed on the inner wall surface of the through hole 16. This spline 16a is engaged with the first spline 131a of the shaft main body 131. The shaft 3 and the cylinder body 4 rotate integrally by means of the respective splines 16a, 131a.

[0070] A recess 20 is formed between the end portion 4a on the bottom wall 119 side from the axial center of the through hole 16 in such a manner as to surround the periphery of the shaft 3. A through hole 25 that penetrates the cylinder body 4 in the axial direction is formed in a portion of the inner wall surface between the axial center of the through hole 16 and the front flange plate 10 side. The spring 23 and the races 24a, 24b, which will be described later, are housed in the recess 20. The coupling member 26, which will be described later, is housed in the through hole 25 in such a manner as to be movable in the axial direction.

[0071] A plurality of cylinder chambers 17 are formed in the cylinder body 4 in such a manner as to surround the periphery of the shaft 3. The plurality of cylinder chambers 17 are disposed at equal intervals along the circumferential direction on a prescribed pitch circle concentric with the center axis C. The cylinder chamber 17 is a recess that is open on the front flange plate 10 side and is closed on the bottom wall 119 side. On the end portion 4a of the cylinder body 4, a communication hole (one example of the cylinder body communication hole in the claims) 18 that communicates each cylinder chamber 17 with the outside of the cylinder body 4 is formed at a position corresponding to each cylinder chamber 17.

[0072] The piston 21 is housed in each cylinder chamber 17 in a manner that is movable in sliding along the axial direction. The piston 21 is thereby rotated in a manner that revolves around the center axis C along with the rotation of the shaft 3 and the cylinder block 4.

[0073] A cavity that stores the working oil in the cylinder chamber 17 is formed in the inside of the piston 21. The sliding movement of the piston 21 is associated with the suction and discharge of the working oil with respect to the cylinder chamber 17.

[0074] That is, when the piston 21 is pulled out of the cylinder chamber 17, the space volume in the cylinder chamber 17 is increased, and the working oil is sucked into the cylinder chamber 17 via the communication hole 18 (suction process). From the bottom dead center at which the piston 21 is pulled out of the cylinder chamber 17 to the maximum extent, the piston 21 is shifted to the action of entering into the cylinder chamber 17. When the piston 21 enters into the cylinder chamber 17, the space volume in the cylinder chamber 17 is decreased, and the working oil is discharged from the cylinder chamber 17 via the communication hole 18 (discharge process). From the top dead center at which the piston 21 enters into the cylinder chamber 17 to the maximum extent, the action of the piston 21 is again shifted to the bottom dead center.

[0075] A spherical convex portion 28 is integrally formed at the end of the piston 21 on the side of the front flange plate 10. A plurality of sliding shoes 22 are installed to the convex portion 28. The sliding shoes 22 are used to associate the sliding movement amount of the piston 21 and the inclination of the tilt plate 5. A spherical concave portion 22a is formed in the surface of the sliding shoe 22 on the side of the housing convex portion 28 in a manner that corresponds to the shape of the convex portion 28. The convex portion 28 of the piston 21 is fitted to the inner wall surface of the concave portion 22a. The sliding shoe 22 is linked to the convex portion 28 of the piston 21 in a manner that is rotatable with respect to the convex portion 28 of the piston 21.

[0076] The spring 23 that is housed in the concave portion 20 of the cylinder block 4 is, for example, a coil spring. The spring 23 is compressed between two seat rings 24a, 24b that are housed in the concave portion 20. The spring 23 generates a pressing force in the direction in which it is elongated due to the elastic force. The pressing force of the spring 23 is transmitted to the link member 26 via one of the two seat rings 24b. The pressing force of the spring 23 is transmitted to the pressing member 27 that is fitted to the outer peripheral surface of the shaft body 131 via the link member 26.

[0077] The tilt plate 5 is provided to the inner surface 10a of the front flange plate 10 on the side of the housing body 9. The tilt plate 5 restricts the displacement of each piston 21 in the direction along the axial direction by being inclined with respect to the front flange plate 10. A through hole 32 through which the shaft 3 is passed is formed in the radial center of the tilt plate 5. The tilt plate 5 has a flat sliding surface 5a that is formed on the side of the cylinder block 4. A plurality of sliding shoes 22 move on this sliding surface 5a.

[0078] The shoes 22 are integrated by shoe holding members 29. The urging members 27 urge the shoe holding members 29 toward the side of the swash plate 5 in contact with the shoe holding members 29. The shoes 22 move in a manner following the sliding surface 5a of the swash plate 5. Thus, the piston 21 that rotates around the center axis C is slidably moved with respect to the cylinder chamber 17. That is, the sliding movement amount of the piston 21 is controlled by the swash plate 5. In other words, the sliding movement amount of the piston 21 is determined by the inclination angle of the swash plate 5. In further words, the swash plate 5 controls the discharge amount of the working oil discharged from the main pump 1. The inclination angle of the swash plate 5 is controlled by an actuator not shown. Details thereof will be described later.

[0079] [First Embodiment]

[0080] <Valve Plate>

[0081] The valve plate 19 is disposed between the end surface 4b of the end portion 4a of the cylinder block 4 and the inner surface 119a of the bottom wall 119 of the housing main body 9. The valve plate 19 is formed in a circular plate shape. The valve plate 19 is provided to the bottom wall 119 of the housing main body 9 in a manner not to rotate. That is, the valve plate 19 does not rotate with respect to the bottom wall 119 of the housing main body 9, but there is a case where the valve plate 19 is separated from the inner surface 119a of the bottom wall 119.

[0082] Even in a case where the cylinder block 4 and the shaft 3 rotate around the center axis C, the valve plate 19 is stationary with respect to the main housing 2 (the housing main body 9). The cylinder block 4 is supported by the static pressure of the oil film of the working oil formed between the valve plate 19 and the end surface 4b of the cylinder block 4.

[0083] Figure 3 is a plan view as viewed from the first face 41a side of the valve plate 19 on the side of the cylinder block 4. Figure 4 is a plan view as viewed from the second face 41b side of the valve plate 19 on the side of the bottom wall 119. Figure 5 is a sectional view along the A-A line of Figure 4 .

[0084] As shown in Figures 3 to 5 , a through hole 42 through which the shaft 3 penetrates is formed in the radial center of the valve plate 19 in a manner penetrating in the thickness direction of the valve plate 19. An inner side recess 43 that is circular ring-shaped as viewed in the axial direction is formed in the first face 41a of the valve plate 19 in a manner surrounding the periphery of the through hole 42 and in a manner communicating with the through hole 42. An outer side recess 44 that is annular along the outer peripheral portion is formed in the first face 41a of the valve plate 19.

[0085] The suction port 19a that communicates with each communication hole 18 of the cylinder block 4 is formed in the valve plate 19 in a manner penetrating in the thickness direction of the valve plate 19. The outer shape of the suction port 19a is, for example, a circular arc shape in a prescribed angle range around the center axis C, and is formed in an oblong shape.

[0086] Each cylinder chamber 17 communicates with the first communication path 124 formed in the housing main body 9 via the suction port 19a of the valve plate 19 and the communication hole 18 of the cylinder body 4.

[0087] The injection port 19b is formed between the second face 41b of the valve plate 19 and the thickness direction center of the valve plate 19. The injection port 19b is formed in a circular shape as viewed in the axial direction. The injection port 19b is disposed on the side opposite to the circumferential center of the suction port 19a with the through hole 42 interposed therebetween.

[0088] A long recessed portion 45 that communicates with the injection port 19b is formed on the side opposite to the suction port 19a with the through hole 42 interposed therebetween between the first face 41a of the valve plate 19 and the thickness direction center of the valve plate 19.

[0089] The long recessed portion 45 communicates with the injection port 19b, and thus the long recessed portion 45 is a part of the injection port 19b. The long recessed portion 45 is, for example, a circular arc shape in a prescribed angular range around the center axis C, and is formed in an oblong shape. The long recessed portion 45 and the suction port 19a are disposed on the same pitch circle.

[0090] Each cylinder chamber 17 communicates with the third communication path 128 formed in the housing main body 9 via the injection port 19b of the valve plate 19, the long recessed portion 45, and the communication hole 18 of the cylinder body 4.

[0091] A pair of switching lands 47a, 47b (lower dead center switching land 47a, upper dead center switching land 47b) are formed between the length direction both ends of the suction port 19a and the length direction both ends of the long recessed portion 45 on the first face 41a of the valve plate 19. In other words, the suction port 19a and the long recessed portion 45 are formed on both sides with the pair of switching lands 47a, 47b interposed therebetween. The pair of switching lands 47a, 47b are coplanar with the first face 41a. The communication hole 18 of the cylinder body 4 is switched to communicate with the suction port 19a or the long recessed portion 45 via the pair of switching lands 47a, 47b when the cylinder body 4 rotates.

[0092] In the following description, the switching land 47a of the pair of switching lands 47a, 47b that corresponds to the position at which the operation of the piston 21 changes from the lower dead center to the upper dead center will be referred to as the lower dead center switching land 47a. The switching land 47b of the pair of switching lands 47a, 47b that corresponds to the position at which the operation of the piston 21 changes from the upper dead center to the lower dead center will be referred to as the upper dead center switching land 47b.

[0093] Piston receiving recesses (an example of the push member receiving recess in the claim) 49 are formed between the second surface 41b of the valve plate 19 and the center of the valve plate 19 in the thickness direction, corresponding to the two ends of the elongated recess 45 in the length direction. These piston receiving recesses 49 are formed in positions that avoid the locations of the first intake path 122 and the ejection path 123 formed in the housing body 9. These avoided locations refer to locations that are not connected to the first intake path 122 and the ejection path 123. That is, the piston receiving recesses 49 are formed in locations that are not connected to the first intake path 122 and the ejection path 123.

[0094] The piston receiving recess 49 is circular in shape when viewed from the axial direction. The diameter of the piston receiving recess 49 is larger than the diameter of the nozzle 19b. The piston receiving recess 49 is connected to both ends of the elongated recess 45 along its length.

[0095] A circular, plate-shaped push piston 46 is housed in the piston receiving recess 49. The central axis Co of the push piston 46 is along the axial direction. The diameter of the push piston 46 is approximately the same as or slightly smaller than the diameter of the piston receiving recess 49.

[0096] Figure 6 It is along Figure 3 A cross-sectional view of the BB line.

[0097] like Figure 3 , Figure 4 , Figure 6 As shown, a notch 50 is formed on the first surface 41a of the valve plate 19, extending from the end of the long recess 45 near the lower dead center switching land 47a towards the lower dead center switching land 47a (the long-distance end of the intake port 19a). The notch 50 is formed such that, viewed axially, it tapers towards the long-distance end of the long recess 45 towards the long-distance end of the intake port 19a. The notch 50 is also formed such that its depth gradually decreases towards the long-distance end of the long recess 45 towards the long-distance end of the intake port 19a.

[0098] On the valve plate 19, a valve plate communication hole 51 is formed on the bottom surface 49a of the piston receiving recess 49 located on the side of the bottom dead center switching land 47a, communicating with the bottom dead center switching land 47a. The valve plate communication hole 51 is a tiny orifice. The valve plate communication hole 51 extends axially. The valve plate communication hole 51 is positioned slightly separated from the front end of the notch 50 towards the end in the length direction near the intake port 19a. The valve plate communication hole 51 communicates with each communication hole 18 of the cylinder block 4.

[0099] <Gear Pump>

[0100] like Figure 2As shown, a gear pump 111 provided on one side of the main pump 1 functions as an additional pump. The gear pump 111 has a gear housing 141 and a drive gear and a driven gear, not shown.

[0101] The rectangular parallelepiped-shaped gear housing 141 is disposed on the outer surface 119b of the bottom wall 119 of the main housing 2. A second suction passage 144 that communicates with the second communication passage 125 of the main housing 2 is formed in a first wall surface 141a of the gear housing 141 that overlaps the main housing 2. The second suction passage 144 communicates the inside and outside of the first wall surface 141a of the gear housing 141.

[0102] In the first wall surface 141a of the gear housing 141, a coupling through hole 149 is formed at a position corresponding to the rotation axis through hole 121 of the main housing 2. The end portion of the coupling 136 on the gear pump 111 side protrudes into the gear housing 141 via the coupling through hole 149.

[0103] In a second wall surface 141b of the gear housing 141 that is orthogonal to the first wall surface 141a and faces in the same direction as the second side surface 119d of the main housing 2, a third discharge passage, not shown, is formed. An opening portion of the third discharge passage is formed in the second wall surface 141b.

[0104] The drive gear and the driven gear, not shown, are rotatably supported in the gear housing 141 and are engaged with each other. The drive gear is linked to the coupling 136 that protrudes from the main housing 2 via the coupling through hole 149. The rotational force of the shaft 3 in the main pump 1 is transmitted to the drive gear via the coupling 136. The driven gear is engaged with the drive gear, and thus, the driven gear rotates in synchronization with the drive gear.

[0105] Action of the Pump Unit

[0106] Next, the action of the pump unit 110 will be described.

[0107] First, the action of the main pump 1 will be described.

[0108] The main pump 1 outputs a driving force generated based on the discharge of the working oil from the cylinder chamber 17 and the suction of the working oil to the cylinder chamber 17.

[0109] More specifically, as the shaft 3 rotates due to the power from the power source such as an engine, the cylinder block 4 rotates integrally with the shaft 3. As the cylinder block 4 rotates, the piston 21 rotates around the center axis C of the shaft 3.

[0110] Due to the urging force of the spring 23, each shoe 22, to which the convex portion 28 of each piston 21 is attached, appropriately follows and presses against the sliding surface 5a of the inclined plate 5 regardless of the inclination angle of the inclined plate 5. The convex portion 28 of the piston 21 is formed in a spherical shape, and the concave portion 22a of the shoe 22, into which the convex portion 28 is fitted, is also formed in a spherical shape. The urging member 27 applies a pressure to each shoe 22 urging toward the inclined plate 5 side by means of the shoe holding member 29. Even if the inclination angle of the inclined plate 5 changes, each shoe 22 appropriately follows and presses against the sliding surface 5a following the inclination of the inclined plate 5.

[0111] With the rotation of the cylinder block 4, if the pistons 21 rotate around the center axis C of the shaft 3, each shoe 22 also moves on the sliding surface 5a of the inclined plate 5 while rotating around the center axis C of the shaft 3. Thereby, each piston 21 reciprocates while slidingly moving in the axial direction within each cylinder chamber 17.

[0112] When the piston 21 changes from the top dead center to the bottom dead center, the cylinder chamber 17 (communication hole 18) in which the piston 21 is accommodated passes through the suction port 19a from the long recessed portion 45 of the valve plate 19 via the top dead center switching land portion 47b. At this time, the working oil is sucked into the cylinder chamber 17 from the first suction passage 122 of the main housing 2 via the first communication passage 124, the suction port 19a, and the communication hole 18 (suction process).

[0113] When the piston 21 changes from the bottom dead center to the top dead center, the cylinder chamber 17 (communication hole 18) in which the piston 21 is accommodated passes through the long recessed portion 45 from the suction port 19a of the valve plate 19 via the bottom dead center switching land portion 47a. At this time, the working oil is ejected from the cylinder chamber 17 via the communication hole 18, the long recessed portion 45, the ejection port 19b, the third communication passage 128, and the ejection passage 123 (ejection process).

[0114] If the inclination angle of the inclined plate 5 (sliding surface 5a) changes, the stroke (movement distance) of the reciprocating motion of the piston 21 changes. The larger the inclination angle of the inclined plate 5, the larger the suction amount and the ejection amount of the working oil with respect to the cylinder chamber 17 generated by the reciprocating motion of each piston 21. The smaller the inclination angle of the inclined plate 5, the smaller the suction amount and the ejection amount of the working oil with respect to the cylinder chamber 17 generated by the reciprocating motion of each piston 21. In the case where the inclination angle of the inclined plate 5 is zero, even if the pistons 21 rotate around the center axis C of the shaft 3, each piston 21 does not perform the reciprocating motion. In the case where the inclination angle of the inclined plate 5 is zero, the ejection amount of the working oil from each cylinder chamber 17 is also zero.

[0115] In the spouting step, the working oil spouted from the cylinder chamber 17 to the long recess 45 is spouted not only to the spouting port 19b but also to the piston housing recess 49. The push-up piston 46 is housed in the piston housing recess 49, and therefore, the push-up piston 46 is pushed up toward the inner surface 119a of the bottom wall 119 in the main housing 2 due to the pressure of the working oil. The push-up force that pushes up the valve plate 19 toward the end surface 4b of the cylinder block 4 is generated due to the reaction force generated because the push-up piston 46 is pushed up toward the inner surface 119a of the bottom wall 119.

[0116] The working oil spouted from the cylinder chamber 17 forms an oil film between the inner surface 119a of the bottom wall 119 and the portion of the second face 41b of the valve plate 19 other than the through hole 42, the suction port 19a, the spouting port 19b, and the piston housing recess 49.

[0117] The push-up force is generated as a force that pushes up the cylinder block 4 toward the valve plate 19 by the pistons 21 housed in each cylinder chamber 17 of the cylinder block 4. The push-up force is a force that pushes up the valve plate 19 toward the cylinder block 4, and there are a reaction force of a force that pushes up the push-up piston 46 by the working oil acting on the cylinder chamber 17, and the like.

[0118] The working oil spouted from the cylinder chamber 17 forms an oil film between the end surface 4b of the cylinder block 4 and the portion of the first face 41a of the valve plate 19 other than the through hole 42, the suction port 19a, the long recess 45, the inner side recess 43, and the outer side recess 44. The reaction force of this oil film becomes a repulsive force that pulls away the valve plate 19 from the end surface 4b of the cylinder block 4. In addition, the repulsive force is a hydraulic pressure that acts on the end surface 4b of the cylinder block 4 from the suction port 19a and the spouting port 19b of the valve plate 19. By balancing these push-up force and the repulsive force, the positional relationship between the cylinder block 4 and the valve plate 19 is appropriately ensured.

[0119] However, at the timing when the cylinder chamber 17 (the communication hole 18) communicates with the long recess 45 (the spouting port 19b) by passing through the bottom dead center switching land 47a, the cylinder chamber 17 is abruptly opened by the long recess 45 (the spouting port 19b), and therefore, it is possible that the working oil is inversely injected into the cylinder chamber 17 due to the pressure difference. The notch 50 formed in the first face 41a of the valve plate 19 functions to moderate the abrupt pressure change of the cylinder chamber 17.

[0120] In addition, in the valve plate 19 of the first embodiment, a valve plate communication hole 51 is formed in the bottom surface 49a of the piston housing recess 49 so as to communicate the bottom surface 49a with the bottom dead center switching land 47a. Therefore, before the cylinder chamber 17 (communication hole 18) is about to communicate with the long recess 45 (discharge port 19b), the cylinder chamber 17 (communication hole 18) communicates with the valve plate communication hole 51. As a result, the pressure of the working oil of the piston housing recess 49 (discharge port 19b) (hereinafter, referred to as the discharge pressure of the working oil) is introduced into the cylinder chamber 17, and the pressure in the cylinder chamber 17 is slightly increased. Thus, it is possible to prevent the working oil from being reversely injected into the cylinder chamber 17 at the time when the cylinder chamber 17 (communication hole 18) communicates with the long recess 45 (discharge port 19b).

[0121] Next, the operation of the gear pump 111 will be described.

[0122] The drive gear of the gear pump 111 is coupled to the shaft 3 of the main pump 1 by means of the coupling 136, and thus, the drive gear rotates integrally with the shaft 3. The driven gear engaged with the drive gear also rotates in synchronization with the drive gear. The working oil flowing in the first suction passage 122 is sucked into the second suction passage 144 via the second communication passage 125 of the main housing 2. The working oil passes between each gear and the inner side surface of the gear housing 141 to flow toward the third discharge passage, not shown. The working oil is discharged via the opening portion of the third discharge passage.

[0123] Thus, the valve plate 19 of the first embodiment described above has the valve plate communication hole 51 formed in the bottom surface 49a of the piston housing recess 49 so as to communicate the bottom surface 49a with the bottom dead center switching land 47a. Therefore, before the cylinder chamber 17 (communication hole 18) is about to communicate with the long recess 45 (discharge port 19b) via the bottom dead center switching land 47a, it is possible to introduce the discharge pressure of the working oil into the cylinder chamber 17 by means of the valve plate communication hole 51. As a result, it is possible to prevent the working oil from being reversely injected into the cylinder chamber 17 at the time when the cylinder chamber 17 (communication hole 18) communicates with the long recess 45 (discharge port 19b). Thus, it is possible to reliably suppress the corrosion of the cylinder chamber 17 due to the reverse injection of the working oil into the cylinder chamber 17.

[0124] The valve plate communication hole 51 is formed using the piston housing recess 49 for generating the pushing pressure of the valve plate 19 toward the cylinder block 4, and thus, it is possible to easily introduce the pressure of the working oil of the discharge port 19b into the valve plate communication hole 51. Therefore, it is possible to suppress the processing cost of the valve plate 19.

[0125] The valve plate communication hole 51 is disposed slightly separated from the position of the length direction end portion of the suction port 19a toward the front end of the notch 50. Therefore, it is possible to reliably introduce the discharge pressure of the working oil into the cylinder chamber 17 before the cylinder chamber 17 (communication hole 18) is about to communicate with the long recess 45 (discharge port 19b) via the bottom dead center switching land 47a.

[0126] A circular plate-shaped push-up piston 46 is housed in the piston housing recess 49 formed in the valve plate 19. By applying the injection pressure of the working oil to the push-up piston 46, it is possible to easily apply the push-up force toward the cylinder block 4 to the valve plate 19.

[0127] [2nd Embodiment]

[0128] Next, based on the same principle as the 1st embodiment, the 2nd embodiment will be described. Figure 7 The 2nd embodiment of the present application will be described.

[0129] Figure 7 is a cross-sectional view of a main part of the valve plate 219 in the 2nd embodiment. Figure 7 Corresponds to the aforementioned Figure 6 The same reference numerals are attached to the same modes as the 1st embodiment, and the description will be omitted.

[0130] As Figure 7 indicated in the 1st embodiment and the 2nd embodiment, the difference between the 1st embodiment and the 2nd embodiment is as follows: In the valve plate 19 of the 1st embodiment, the valve plate communication hole 51 is arranged at a position slightly separated from the front end of the notch 50, and in contrast, in the valve plate 219 of the 2nd embodiment, the valve plate communication hole 52 is arranged at the front end of the notch 50. In the 2nd embodiment, the valve plate communication hole 52 communicates with the notch 50 on the 1st face 41a side of the valve plate 219.

[0131] The switching land portions 47a, 47b of the valve plate 219 are formed by grinding the valve plate 219 at the time of finish machining of the valve plate 219. At this time, by forming the valve plate communication hole 52 at the front end of the notch 50, it is possible to prevent the distance between the notch 50 and the valve plate communication hole 52 from changing due to the grinding amount. That is, the position of the front end of the notch 50 changes due to the grinding amount, but by forming the valve plate communication hole 52 at the front end of the notch 50, it is possible to prevent the distance between the notch 50 and the valve plate communication hole 52 from changing. In other words, regardless of the grinding amount, the valve plate communication hole 52 always communicates with the notch 50 on the 1st face 41a side of the valve plate 219. Therefore, regardless of the grinding amount, it is possible to stabilize the effect of the valve plate communication hole 52.

[0132] The present application is not limited to the above-described embodiments, and includes embodiments obtained by applying various modifications to the above-described embodiments within a range not departing from the gist of the present application.

[0133] For example, in the above-described embodiments, the case where the construction machine 100 is a hydraulic excavator is described. However, this is not limiting, and various construction machines can be adopted.

[0134] In the above-described embodiment, the main pump 1 using working oil as a fluid was described as a fluid machine. However, the structure of the valve plate 19, 219 described above can be adopted in various fluid machines using various fluids other than working oil.

[0135] In the above-described embodiment, the case where the valve plate communication hole 51 that communicates the bottom surface 49a of the piston housing recess 49 with the lower dead center switching land 47a is formed in the bottom surface 49a of the piston housing recess 49 disposed on the lower dead center switching land 47a side was described. However, this is not limiting, and the valve plate communication hole 51 that communicates the bottom surface 49a of the piston housing recess 49 with the upper dead center switching land 47b can be formed in the bottom surface 49a of the piston housing recess 49 disposed on the upper dead center switching land 47b side.

[0136] In the above-described embodiment, the case where the round plate-shaped push-up piston 46 is housed in the piston housing recess 49 formed in the valve plate 19 was described. However, it is sufficient that the pressure of the working oil sprayed into the piston housing recess 49 generates a push-up force toward the cylinder 4 in the valve plate 19. For example, the push-up piston 46 can not be provided in the piston housing recess 49. Instead of the push-up piston 46, a compression coil spring or the like can be housed in the piston housing recess 49. The elastic force of the compression coil spring can be used to apply a push-up force toward the cylinder 4 to the valve plate 19.

[0137] In the above-described embodiment, the case where the piston housing recess 49 is formed in the valve plate 19 at positions corresponding to both ends of the length direction of the long recess 45 was described. However, this is not limiting, and it is sufficient that the piston housing recess 49 is formed at a position (a position that is not communicated with the first suction passage 122 and the discharge passage 123) that avoids the first suction passage 122 and the discharge passage 123. It is sufficient that the pressure of the working oil sprayed into the piston housing recess 49 via the valve plate communication hole 51 generates a push-up force toward the cylinder 4 in the valve plate 19.

[0138] This is because, if the piston housing recess 49 is communicated with the first suction passage 122 and the discharge passage 123, the working oil sprayed into the piston housing recess 49 leaks into these first suction passage 122 and discharge passage 123. If configured as such, it is difficult to generate a push-up force toward the cylinder 4 in the valve plate 19 using the pressure of the working oil sprayed into the piston housing recess 49.

[0139] In the above-described embodiment, the case where the valve plate communication hole 51 formed in the valve plate 19 extends along the axial direction was described. However, this is not limiting, and it is sufficient that the valve plate communication hole 51 is formed in such a manner that the piston housing recess 49 of the valve plate 19 is communicated with the switching lands 47a, 47b.

[0140] In the embodiments disclosed in the present specification, for a member composed of a plurality of objects, the plurality of objects can be integrated, and conversely, for a member composed of one object, it can be divided into a plurality of objects. Whether or not integrated, as long as it is configured in a manner that the object of the present invention can be achieved.

Claims

1. A fluid machine, wherein, This fluid machinery has the following features: A cylinder block having a cylinder chamber and a cylinder block communication hole that connects the inside and outside of the cylinder chamber; A piston is housed in the cylinder chamber in a sliding manner, and the piston performs an ejection process that compresses the cylinder chamber and an intake process that expands the cylinder chamber. A housing that houses the cylinder, the housing having an intake path and an exhaust path; A valve plate, disposed between the cylinder and the housing; and A pushing member that pushes the valve plate toward the cylinder body. The valve plate has: The intake port connects the cylinder communication hole to the intake path; The nozzle is formed on the opposite side of the intake port in such a way that it is sandwiched between a pair of switching lands formed on the first surface of the valve plate on the cylinder side, and the nozzle communicates the cylinder communication hole with the ejection path. A pusher member receiving recess is formed on the valve plate at a position on the second side opposite to the first side, avoiding the suction path and the ejection path, and the pusher member receiving recess receives the pusher member. A valve plate connecting hole allows the push member receiving recess to communicate with the switching land section; as well as An elongated recess, formed between the first surface and the center of the valve plate in the thickness direction, communicates with the nozzle. The pusher member's receiving recess is connected to both ends of the elongated recess along its length.

2. The fluid machinery according to claim 1, wherein, A notch is formed in the valve plate. The land section located at the bottom dead center position of the piston when it switches from the suction process to the ejection process is defined as the bottom dead center switching land section. The notch extends from the jet outlet toward the lower dead center switching land section. The valve plate communication hole is positioned at a point that separates from the front end of the notch towards the suction port side. The front end of the notch is defined as the end on the side opposite to the nozzle.

3. The fluid machinery according to claim 1, wherein, A notch is formed in the valve plate. The land section located at the bottom dead center position of the piston when it switches from the suction process to the ejection process is defined as the bottom dead center switching land section. The notch extends from the jet outlet toward the lower dead center switching land section. The valve plate communication hole is located at the front end of the notch. The front end of the notch is defined as the end on the side opposite to the nozzle.

4. The fluid machinery according to any one of claims 1 to 3, wherein, The pushing component is a small, circular piston.

5. A fluid machine, wherein, This fluid machinery has the following features: A cylinder block having a cylinder chamber and a cylinder block communication hole that connects the inside and outside of the cylinder chamber; A piston is housed in the cylinder chamber in a sliding manner, and the piston performs an ejection process that compresses the cylinder chamber and an intake process that expands the cylinder chamber. A housing that houses the cylinder, the housing having an intake path and an exhaust path; A valve plate, disposed between the cylinder and the housing; and A pushing member that pushes the valve plate toward the cylinder body. The valve plate has: The intake port connects the cylinder communication hole to the intake path; The nozzle is formed on the opposite side of the intake port in such a way that it is sandwiched between a pair of switching lands formed on the first surface of the valve plate on the cylinder side, and the nozzle communicates the cylinder communication hole with the ejection path. A push member receiving recess is formed on the valve plate on the second side opposite to the first side, avoiding the position of the inlet and the outlet. The push member receiving recess receives the push member. A notch that extends from the nozzle toward the lower dead center switching land section; A valve plate communication hole, positioned at a point separating from the front end of the notch towards the suction port side, allows communication between the push member receiving recess and the switching section; and An elongated recess, formed between the first surface and the center of the valve plate in the thickness direction, communicates with the nozzle. The bottom dead center switching land section is defined as the land section of the pair of switching land sections that is positioned at the bottom dead center when the piston switches from the suction process to the ejection process. The front end of the notch is defined as the end on the side opposite to the nozzle. The pusher member's receiving recess is connected to both ends of the elongated recess along its length.

6. A fluid machine, wherein, This fluid machinery has the following features: A cylinder block having a cylinder chamber and a cylinder block communication hole that connects the inside and outside of the cylinder chamber; A piston is housed in the cylinder chamber in a sliding manner, and the piston performs an ejection process that compresses the cylinder chamber and an intake process that expands the cylinder chamber. A housing that houses the cylinder, the housing having an intake path and an exhaust path; A valve plate, disposed between the cylinder and the housing; and A pushing member that pushes the valve plate toward the cylinder body. The valve plate has: The intake port connects the cylinder communication hole to the intake path; The nozzle is formed on the opposite side of the intake port in such a way that it is sandwiched between a pair of switching lands formed on the first surface of the valve plate on the cylinder side, and the nozzle communicates the cylinder communication hole with the ejection path. A push member receiving recess is formed on the valve plate on the second side opposite to the first side, avoiding the position of the inlet and the outlet. The push member receiving recess receives the push member. A notch that extends from the nozzle toward the lower dead center switching land section; A valve plate connecting hole, disposed at the front end of the notch, allows the push member receiving recess to communicate with the switching land portion; and An elongated recess, formed between the first surface and the center of the valve plate in the thickness direction, communicates with the nozzle. The bottom dead center switching land section is defined as the land section of the pair of switching land sections that is positioned at the bottom dead center when the piston switches from the suction process to the ejection process. The front end of the notch is defined as the end on the side opposite to the nozzle. The pusher member's receiving recess is connected to both ends of the elongated recess along its length.

7. A construction machine, wherein, This construction machinery has the following features: Body; and Fluid machinery that draws in and ejects fluid that serves as the driving source for the vehicle body. The fluid machinery includes: A cylinder block having a cylinder chamber and a cylinder block communication hole that connects the inside and outside of the cylinder chamber; A piston is housed in the cylinder chamber in a sliding manner, and the piston performs an ejection process that compresses the cylinder chamber and an intake process that expands the cylinder chamber. A housing that houses the cylinder, the housing having an intake path and an exhaust path; A valve plate, disposed between the cylinder and the housing; and A pushing member that pushes the valve plate toward the cylinder body. The valve plate has: The intake port connects the cylinder communication hole to the intake path; The nozzle is formed on the opposite side of the intake port in such a way that it is sandwiched between a pair of switching lands formed on the first surface of the valve plate on the cylinder side, and the nozzle communicates the cylinder communication hole with the ejection path. A push member receiving recess is formed on the valve plate on the second side opposite to the first side, avoiding the position of the inlet and the outlet. The push member receiving recess receives the push member. A notch that extends from the nozzle toward the lower dead center switching land section; A valve plate communication hole, positioned at a point separating from the front end of the notch towards the suction port side, allows communication between the push member receiving recess and the switching section; and An elongated recess, formed between the first surface and the center of the valve plate in the thickness direction, communicates with the nozzle. The bottom dead center switching land section is defined as the land section of the pair of switching land sections that is positioned at the bottom dead center when the piston switches from the suction process to the ejection process. The front end of the notch is defined as the end on the side opposite to the nozzle. The pusher member's receiving recess is connected to both ends of the elongated recess along its length.

8. A construction machine, wherein, This construction machinery has the following features: Body; and Fluid machinery that draws in and ejects fluid that serves as the driving source for the vehicle body. The fluid machinery includes: A cylinder block having a cylinder chamber and a cylinder block communication hole that connects the inside and outside of the cylinder chamber; A piston is housed in the cylinder chamber in a sliding manner, and the piston performs an ejection process that compresses the cylinder chamber and an intake process that expands the cylinder chamber. A housing that houses the cylinder, the housing having an intake path and an exhaust path; A valve plate, disposed between the cylinder and the housing; and A pushing member that pushes the valve plate toward the cylinder body. The valve plate has: The intake port connects the cylinder communication hole to the intake path; The nozzle is formed on the opposite side of the intake port in such a way that it is sandwiched between a pair of switching lands formed on the first surface of the valve plate on the cylinder side, and the nozzle communicates the cylinder communication hole with the ejection path. A push member receiving recess is formed on the valve plate on the second side opposite to the first side, avoiding the position of the inlet and the outlet. The push member receiving recess receives the push member. A notch that extends from the nozzle toward the lower dead center switching land section; A valve plate connecting hole, disposed at the front end of the notch, allows the push member receiving recess to communicate with the switching land portion; and An elongated recess, formed between the first surface and the center of the valve plate in the thickness direction, communicates with the nozzle. The bottom dead center switching land section is defined as the land section of the pair of switching land sections that is positioned at the bottom dead center when the piston switches from the suction process to the ejection process. The front end of the notch is defined as the end on the side opposite to the nozzle. The pusher member's receiving recess is connected to both ends of the elongated recess along its length.

Images