CN112240274A

CN112240274A - Fluid machine and construction machine

Info

Publication number: CN112240274A
Application number: CN202010688411.XA
Authority: CN
Inventors: 蒲田宏树
Original assignee: Nabtesco Corp
Current assignee: Nabtesco Corp
Priority date: 2019-07-19
Filing date: 2020-07-16
Publication date: 2021-01-19
Also published as: JP7430495B2; KR20210010385A; JP2021017846A

Abstract

The invention provides a fluid machine and a construction machine. A fluid machine of the present invention includes: a housing; a cylinder block having a cylinder chamber for accommodating a piston; and a valve plate located between the housing and an end surface of the cylinder block, wherein the valve plate has a discharge port at a 1 st end surface, the discharge port communicating with a discharge port of a working fluid provided to the housing, and communicating with the cylinder chamber in accordance with rotation of the cylinder block, the valve plate having a pressure acting chamber at a 2 nd end surface opposite to the housing, the pressure acting chamber being acted on by a pressure of the discharge port.

Description

Fluid machine and construction machine

Technical Field

The present invention relates to a fluid machine and a construction machine.

Background

As a hydraulic pump mounted on a construction machine such as a hydraulic excavator, there is a so-called swash plate type hydraulic piston pump. The swash plate type hydraulic piston pump includes, for example: a shaft rotatably supported within the pump housing; a cylinder fixed to an outer peripheral surface of the shaft; and a plurality of pistons. A cylinder block formed with a plurality of cylinder bores and a plurality of pistons inserted into the plurality of cylinder bores form a plurality of cylinder chambers within the cylinder block.

The swash plate type hydraulic piston pump includes: a swash plate disposed on the 1 st end side in the axial direction of the cylinder block; and a valve plate disposed on the 2 nd end portion side opposite to the 1 st end portion. The swash plate restricts sliding of the pistons in the cylinder bores by the end portions of the pistons that are movable on the surface of the swash plate. The swash plate changes the volume of the cylinder chamber according to the inclination angle with respect to the pump housing. In the valve plate, a suction path and a discharge path through which the hydraulic oil flows are formed at positions corresponding to the plurality of cylinder bores of the cylinder block.

In the swash plate type hydraulic piston pump, when the cylinder block rotates about the axis of the shaft, each cylinder chamber rotates about the shaft to alternately communicate with the suction path and the discharge path of the valve plate. At the time when the cylinder chamber communicates with the suction path, the piston slides within the cylinder hole to enlarge the cylinder chamber. Thereby, the working oil is sucked from the outside of the pump housing into the cylinder chamber through the suction path. On the other hand, at the time when the cylinder chamber communicates with the discharge path, the piston slides in the cylinder hole to reduce the cylinder chamber. Thereby, the working oil is discharged from the cylinder chamber to the outside of the pump housing through the discharge path.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 52-35304

Patent document 2: japanese laid-open patent publication No. 1-267367

Disclosure of Invention

Problems to be solved by the invention

There is a so-called split flow type hydraulic piston pump in which a discharge path of the hydraulic oil is divided into two on the inner circumferential side and the outer circumferential side in the radial direction with respect to a single cylinder. The hydraulic piston pump of the bypass type can perform discharge of two independent systems while suppressing an increase in size of the structure, as compared with a case where a plurality of cylinders are provided, such as a tandem type.

However, with the hydraulic piston pump of the split flow type, there are cases where: as the discharge path is divided into two, a positional difference between a point of action of a pressing force generated by each piston to press the cylinder against the valve plate and a point of action of a separating force to separate the cylinder from the valve plate by the oil pressure of the hydraulic oil increases. The pressing force is an oil pressure acting on the cylinder port, and is a discharge reaction force of the hydraulic oil acting in the cylinder chamber. The repulsive force is an oil film reaction force between the end surface of the cylinder block and the valve plate and an oil pressure acting on the end surface of the cylinder block from the suction path and the discharge path of the valve plate.

In the case where the valve plate is deformed due to an increase in the difference in the position of the point of action between the pressing force and the biasing force, the biasing force increases due to an increase in the area of the oil film reaction force surface between the valve plate and the pump housing. As a result, the following possibilities exist: the floating of the cylinder causes local oil film breakage, and abrasion between the end surface of the cylinder and the valve plate increases. In addition, there is a possibility that: the leakage of the working oil between the valve plate and the pump housing due to the floating of the valve plate is increased, and the volumetric efficiency is lowered.

The invention provides a fluid machine and a construction machine, which can inhibit the deformation of a valve plate and improve the efficiency.

Means for solving the problems

A fluid machine according to an aspect of the present invention includes: a housing; a cylinder block having a cylinder chamber for accommodating a piston; and a valve plate located between the housing and an end surface of the cylinder block, wherein the valve plate has a discharge port at a 1 st end surface, the discharge port communicating with a discharge port of a working fluid provided to the housing, and communicating with the cylinder chamber in accordance with rotation of the cylinder block, the valve plate having a pressure acting chamber at a 2 nd end surface opposite to the housing, the pressure acting chamber being acted on by a pressure of the discharge port.

With this configuration, even when the separating force generated by the pressure of the working fluid between the end surface of the cylinder block and the valve plate increases, the pressure can be applied in the opposite direction from the end surface of the valve plate on the housing side with respect to the reaction force of the separating force acting on the valve plate. Therefore, deformation of the valve plate can be suppressed.

Another aspect of the present invention provides a fluid machine including: a housing; a cylinder block having a cylinder chamber for accommodating a piston; and a valve plate located between the housing and an end surface of the cylinder block, the valve plate having a discharge port at a 1 st end surface, the discharge port communicating with a discharge port of a working fluid provided to the housing, and communicating with the cylinder chamber in accordance with rotation of the cylinder block, the valve plate having a pressure acting chamber connected to the discharge port by a passage at a 2 nd end surface opposing the housing.

In the above configuration, the valve plate may have another discharge port communicating with the cylinder chamber in accordance with rotation of the cylinder block.

In the above configuration, the fluid machine may be configured such that the pressure acting chamber is provided in a region surrounded by two straight lines connecting both ends in the circumferential direction of one of the discharge port and the other discharge port and the central axis of the cylinder, and a radially inner peripheral edge of the discharge port.

In the above-described configuration, the fluid machine may be configured such that the pressure acting chamber is provided in a corresponding region on a straight line connecting an acting point of the pressing force generated by the piston and an acting point of a separating force generated by the pressure of the working fluid at the end surface of the cylinder.

In the above configuration, the pressure acting chamber may be a recess provided in the 2 nd end surface facing the housing.

Another aspect of the present invention provides a fluid machine including: a cylinder block having a plurality of cylinder chambers for accommodating pistons; a housing in which a suction port and a discharge port for working fluid are formed; a valve plate disposed between an end surface of the cylinder block and the housing, the valve plate including: a valve plate suction port that communicates with the suction port and communicates with each of the cylinder chambers in accordance with rotation of the cylinder block; and an inner peripheral side discharge port and an outer peripheral side discharge port that communicate with the discharge port between an end surface of the cylinder block and the housing, and that selectively communicate with each of the cylinder chambers in accordance with rotation of the cylinder block; and a pressure acting chamber which is located on an end surface of the valve plate close to the housing side, and which has: pressure receiving recesses formed in respective regions on a straight line connecting an action point of the pressing force generated by the piston and an action point of a deviation force generated by the pressure of the working fluid between the end surface of the cylinder block and the valve plate; and a passage that communicates either the inner peripheral side discharge port or the outer peripheral side discharge port with the pressure receiving pocket, and the pressure acting chamber acts in a direction in which a pressure of at least either the inner peripheral side discharge port or the outer peripheral side discharge port acts toward the cylinder block side on an end surface of the valve plate on the housing side.

With this configuration, deformation of the valve plate can be suppressed, and the drive efficiency of the fluid machine can be improved.

Another aspect of the present invention provides a fluid machine including: a cylinder block having a plurality of cylinder chambers for accommodating pistons; a valve plate disposed on an end surface of the cylinder block, the valve plate having a valve plate suction port, an inner peripheral side discharge port, and an outer peripheral side discharge port for the working fluid that communicates with each of the cylinder chambers in accordance with rotation of the cylinder block; and a housing disposed on the opposite side of the cylinder block with the valve plate interposed therebetween, the housing including: a suction port for the working fluid, which communicates with the valve plate suction port; an outlet that communicates with the inner peripheral side discharge port and the outer peripheral side discharge port, respectively; and a pressure acting chamber that acts a pressure of the discharge port on the valve plate in a direction toward the cylinder block side on an end surface of the housing on the valve plate side.

With this configuration, even when the separating force generated by the pressure of the working fluid between the end surface of the cylinder block and the valve plate increases, the reaction force of the pressure against the separating force acting on the valve plate can be caused to act between the housing and the valve plate. Therefore, deformation of the valve plate can be suppressed.

In the above-described configuration, the fluid machine may be configured such that the other pressure acting chamber is provided in a region corresponding to a range surrounded by two straight lines connecting both ends in the circumferential direction of either one of the inner peripheral side discharge port and the outer peripheral side discharge port and the central axis of the cylinder block and a radially inner peripheral edge of the inner peripheral side discharge port.

In the above-described configuration, the other pressure acting chambers may be provided in respective regions on a straight line connecting an acting point of the pressing force generated by the piston and an acting point of a separating force generated by the pressure of the working fluid at the end surface of the cylinder.

In the above configuration, the other pressure acting chamber may include: another cylinder chamber formed in an end surface of the housing on the valve plate side; and another piston housed in the other cylinder chamber and configured to apply pressure to the valve plate.

Another aspect of the present invention provides a fluid machine including: a cylinder block having a plurality of cylinder chambers for accommodating pistons; a valve plate disposed on an end surface of the cylinder block, the valve plate having a valve plate suction port, an inner peripheral side discharge port, and an outer peripheral side discharge port for the working fluid that communicates with each of the cylinder chambers in accordance with rotation of the cylinder block; a housing disposed on a side opposite to the cylinder block with the valve plate interposed therebetween, and including: a suction port for the working fluid, which communicates with the valve plate suction port; an outlet that communicates with the inner peripheral side discharge port and the outer peripheral side discharge port, respectively; and a pressure acting chamber having another piston accommodated in another cylinder chamber and acting pressure on the valve plate, wherein the other cylinder chamber is formed in a corresponding region on an end surface of the housing on the valve plate side and on a straight line connecting an acting point of the pressing force generated by the piston and an acting point of a separating force generated by the pressure of the working fluid between the end surface of the cylinder block and the valve plate.

With this configuration, deformation of the valve plate can be suppressed, and the drive efficiency of the fluid machine can be improved. In addition, compared with the case where the pressure acting portion is provided in the valve plate, the layout restriction can be reduced. The other piston can be easily disposed at an appropriate position of the housing.

A construction machine according to another aspect of the present invention includes a vehicle body on which the above-described fluid machine is mounted.

With this configuration, a construction machine capable of improving driving efficiency can be provided.

ADVANTAGEOUS EFFECTS OF INVENTION

The fluid machine and the construction machine described above can suppress deformation of the valve plate and achieve an improvement in efficiency.

Drawings

Fig. 1 is a schematic configuration diagram of a construction machine according to an embodiment of the present invention.

Fig. 2 is a structural view showing a pump unit according to an embodiment of the present invention in a cutaway view.

Fig. 3 is a view schematically showing an end surface of a cylinder of a pump unit according to an embodiment of the present invention.

Fig. 4 is a schematic view showing an end surface of a valve plate on the cylinder block side of the pump unit according to the embodiment of the present invention.

Fig. 5 is a view schematically showing an end surface of a valve plate on the side opposite to a cylinder block in a pump unit according to an embodiment of the present invention.

Fig. 6 is a view schematically showing a cross section of a cylinder block, a valve plate, and a bottom wall of a housing main body of a pump unit according to an embodiment of the present invention.

Fig. 7 is a graph showing an example of the amount of deformation of the valve plate according to the radial direction position of the pump unit according to the embodiment of the present invention and the comparative example.

Fig. 8 is a view schematically showing an end surface of a valve plate on the cylinder block side of a pump unit according to modification 1 of the embodiment of the present invention.

Fig. 9 is a view schematically showing an end surface of a valve plate on the side opposite to a cylinder block in a pump unit according to modification 1 of the embodiment of the present invention.

Fig. 10 is a view schematically showing a cross section of a cylinder block, a valve plate, and a bottom wall of a housing main body of a pump unit according to modification 2 of the embodiment of the present invention.

Description of the reference numerals

1. A main pump (fluid machine); 2. a main housing (casing); 3. a shaft; 4. a cylinder body; 4A, an end face (end face of the cylinder body); 9. a case main body (case); 17. a cylinder bore (cylinder chamber (1 st cylinder chamber)); 19. a valve plate; 19a, a supply port (valve plate suction port); 19b, an outer peripheral side discharge port (other discharge port (2 nd discharge port); outer peripheral side discharge port); 19c, an inner peripheral side discharge port (1 st discharge port); inner peripheral side discharge port); 19A, 1 st end face; 19B, 2 nd end face (end face on the housing side); 21. a piston (1 st piston); 100. a construction machine; 101. a revolving body (vehicle body); 102. a traveling body (vehicle body); 110. a pump unit (fluid machine); 111. a gear pump; 119. a bottom wall; 119a, inner surface (end surface); 122. the 1 st suction path (suction port); 123a, the 1 st discharge path (discharge port); 123b, 2 nd discharge path (discharge port); 191. an outer peripheral side recess (discharge port, outer peripheral side discharge port); 192. an inner peripheral side recess (discharge port, inner peripheral side discharge port); 193. a pressure acting portion (pressure acting chamber); 193A, 195A, a pressure-receiving concave portion (pit); 194. a passage; 195. a pressure acting portion (pressure acting chamber); 196. pistons (other pistons (2 nd piston)); 197. a cylinder bore (the other cylinder chamber (2 nd cylinder chamber)); 293. a pressure acting portion (other pressure acting chamber); C. a central axis (axis); pa, the action point of the pressing force; pb, point of action of the deviating force; la, straight line; lb, straight line.

Detailed Description

Embodiments of the present invention are explained based on the drawings.

Construction machine

Fig. 1 is a schematic configuration diagram of a construction machine 100.

As shown in fig. 1, a construction machine (an example of a construction machine according to the claims) 100 is, for example, a hydraulic excavator or the like. The construction machine 100 includes a revolving structure (an example of a vehicle body in the claims) 101 and a traveling structure (an example of a vehicle body in the claims) 102. Revolving unit 101 revolves in an upper portion of traveling unit 102. The rotator 101 includes a pump unit (an example of a fluid machine according to the present invention) 110.

Rotator 101 includes: cab 103, boom 104, arm 105, and bucket 106. Cab 103 supports an operator riding on revolving unit 101. One end of boom 104 is connected to cab 103. Boom 104 swings with respect to cab 103. One end of the arm 105 is coupled to the other end (tip end) of the boom 104 on the side opposite to the cab 103. The arm 105 swings with respect to the boom 104. Bucket 106 is coupled to the other end (tip end) of arm 105 on the side opposite to boom 104. The bucket 106 swings with respect to the stick 105.

The pump unit 110 is disposed in the cab 103. The operating oil (an example of the working fluid in the claims) supplied from the pump unit 110 drives the cab 103, the boom 104, the arm 105, and the bucket 106.

< Pump Unit >

Fig. 2 is a structural view showing a part of the pump unit 110 in section.

The pump unit 110 is a so-called hydraulic pump for sucking and discharging working oil. As shown in fig. 2, the pump unit 110 includes a main pump (an example of the fluid machine according to the claims) 1 and a gear pump 111 as an additional pump, which are integrated. Fig. 2 shows only the main pump 1 in a section along the axial direction.

< Main Pump >

The main pump 1 is a so-called swash plate type variable displacement hydraulic pump. The main pump 1 mainly includes: a main housing (an example of a housing of claims) 2, a shaft 3, a cylinder block 4, and a swash plate 5. The shaft 3 rotates about an axis, the central axis C, relative to the main housing 2. The cylinder 4 is housed in the main casing 2 and is fixed to the shaft 3. The swash plate 5 is housed in the main casing 2, and rotates relative to the main casing 2 to control the discharge amount of hydraulic oil discharged from the main pump 1.

In fig. 2, the scale of each member is appropriately changed to facilitate understanding of the description. In the following description, a direction parallel to the central axis C of the shaft 3 is referred to as an axial direction, a rotation direction 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.

The main casing 2 includes: a box-shaped case main body (an example of the case of the claims) 9 having an opening 9 a; and a front flange 10 that closes the opening 9a of the case main body 9.

The case body 9 is provided with a bottom wall 119 on the side opposite to the opening 9 a. The cylinder 4 is disposed on the inner surface (an example of an end surface on the valve plate side of the housing in the claims) 119a side of the bottom wall 119. The gear pump 111 is mounted to an outer surface 119b of the bottom wall 119.

A rotation shaft insertion hole 121 through which the shaft 3 can be inserted is formed in the bottom wall 119 so as to penetrate in the plate thickness direction of the bottom wall 119. A bearing 11 for rotatably supporting one end of the shaft 3 is provided on the inner surface 119a of the bottom wall 119. The bottom wall 119 is a wall portion of the housing main body 9 located on the central axis C of the shaft 3.

On both sides of the bottom wall 119 in the radial direction with respect to the shaft 3, a 1 st suction path (an example of a suction port in the claims) 122, a 1 st discharge path (an example of a discharge port in the claims) 123a, and a 2 nd discharge path (an example of a discharge port in the claims) 123b are formed. The 1 st suction path 122 communicates with a suction port 122a formed in the 1 st side surface 119c of the bottom wall 119. The suction port 122a communicates with a tank not shown. The 1 st suction path 122 extends in the bottom wall 119 so that the opening area becomes gradually smaller from the 1 st side surface 119c toward the shaft 3.

A 1 st communication path 124 communicating the 1 st suction path 122 with the inner surface 119a of the bottom wall 119 is formed at an end portion of the 1 st suction path 122 on the shaft 3 side. The 1 st communication path 124 connects and communicates the 1 st suction path 122 with a supply port (an example of a valve plate suction port of the claims) 19a of a valve plate 19 discussed later.

A 2 nd communication path 125 communicating the 1 st suction path 122 with the outer surface 119b of the bottom wall 119 is formed at an end portion of the 1 st suction path 122 on the shaft 3 side. The 2 nd communication path 125 communicates the 1 st suction path 122 with a 2 nd suction path 144, which is discussed later, of the gear pump 111.

An O-ring groove 118 is formed on an outer surface 119b of the bottom wall 119 so as to surround the rotation shaft insertion hole 121 and the 2 nd communication path 125. The O-ring 117 is fixedly mounted in an O-ring groove 118. The O-ring seal 117 ensures sealability between the main housing 2 and the gear housing 141 of the gear pump 111 discussed later.

With this configuration, the working oil is sucked into the 1 st suction path 122 through the suction port 122a from a tank not shown. The working oil sucked into the 1 st suction path 122 flows to the 1 st communication path 124 and the 2 nd communication path 125.

The 1 st discharge path 123a and the 2 nd discharge path 123b have respective discharge ports (not shown) formed in the 2 nd side surface 119d located on the opposite side of the 1 st side surface 119c of the bottom wall 119 with the shaft 3 interposed therebetween. Each discharge port is connected to cab 103, boom 104, arm 105, and bucket 106 via a control valve or the like, not shown. The 1 st discharge path 123a and the 2 nd discharge path 123b extend in the bottom wall 119 from the 2 nd side surface 119d toward the shaft 3.

A 3 rd communication path 128a communicating the 1 st discharge path 123a with the inner surface 119a of the bottom wall 119 is formed at an end portion of the 1 st discharge path 123a on the shaft 3 side. The 3 rd communication path 128a connects and communicates the 1 st discharge path 123a with an outer peripheral side discharge port (other discharge port, an example of an outer peripheral side discharge port in the claims) 19b of the valve plate 19, which will be discussed later.

A 4 th communication path 128b communicating the 2 nd discharge path 123b with the inner surface 119a of the bottom wall 119 is formed at an end portion of the 2 nd discharge path 123b on the shaft 3 side. The 4 th communication path 128b communicates by connecting the 2 nd discharge path 123b to an inner peripheral side discharge port (an example of a discharge port, an inner peripheral side discharge port in the claims) 19c of the valve plate 19 discussed later.

The front flange 10 is formed with a through hole 13 through which the shaft 3 can be inserted. A bearing 14 that rotatably supports the other end side of the shaft 3 is provided in the through hole 13. The oil seal 15 is provided in the through hole 13 at a position on the opposite side of the bearing 14 from the housing main body 9 (outside the front flange 10).

Two mounting plates 137 for fixing the main pump 1 to the revolving structure 101 and the like are integrally formed with the front flange 10. The two mounting plates 137 are disposed on both sides in the radial direction with the shaft 3 interposed therebetween. The mounting plate 137 extends toward the radially outer side.

The shaft 3 is formed to have a step shape. The shaft 3 includes a rotating shaft main body 131, a 1 st bearing portion 132, a transmission shaft 133, a 2 nd bearing portion 134, and a connecting shaft 135, which are arranged coaxially. The rotation shaft main body 131 is disposed in the main casing 2. The 1 st bearing portion 132 is integrally formed with an end portion of the rotation shaft main body 131 on the side of the bottom wall 119 of the housing main body 9. The transmission shaft 133 is integrally formed with an end portion of the 1 st bearing portion 132 on the side opposite to the rotation shaft main body 131. The 2 nd bearing portion 134 is integrally formed with an end portion of the rotary shaft main body 131 on the front flange 10 side. The coupling shaft 135 is integrally formed with an end portion of the 2 nd bearing 134 on the opposite side of the rotation shaft main body 131.

The 2 nd spline 131a is formed in the rotation shaft main body 131. Cylinder 4 is fitted to 2 nd spline 131a of rotary shaft main body 131.

The 1 st bearing portion 132 has a smaller shaft diameter than the shaft diameter of the rotation shaft main body 131. The 1 st bearing portion 132 is rotatably supported by the bearing 11 at the bottom wall 119.

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 1 st bearing 132. The transmission shaft 133 protrudes to the gear pump 111 side through the bearing 11. The transmission shaft 133 is disposed in 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 gear pump 111 side portion of the coupling 136 protrudes toward the gear pump 111 side with respect to the bottom wall 119. The coupling 136 is coupled to the gear pump 111 at a portion protruding toward the gear pump 111.

The shaft diameter of the 2 nd bearing portion 134 is larger than the shaft diameter of the 1 st bearing portion 132. The 2 nd bearing portion 134 is rotatably supported by the bearing 14 of the front flange 10.

The coupling shaft 135 is coupled to a power source such as an engine, not shown. The coupling shaft 135 has a smaller shaft diameter than the 2 nd bearing 134. The tip end of the coupling shaft 135 protrudes outside the front flange 10 through the bearing 14. The oil seal 15 prevents the working oil from flowing out from the inside, and prevents foreign matter and the like from entering between the front flange 10 and the distal end portion of the coupling shaft 135. A 1 st spline 135a is formed at the tip of the coupling shaft 135. A power source such as an engine, not shown, is coupled to the shaft 3 via the 1 st spline 135 a.

Fig. 3 is a view schematically showing an end surface 4A of the end portion 4A of the cylinder 4 of the pump unit 110.

As shown in fig. 2 and 3, a cylinder (an example of a cylinder according to the claims) 4 is formed in a cylindrical shape. A through hole 16 into which the shaft 3 can be inserted or press-fitted is formed at the radial center of the cylinder 4. The through hole 16 has an inner wall surface formed with a spline 16 a. The spline 16a is coupled with the 2 nd spline 131a of the rotation shaft body 131. The shaft 3 and the cylinder 4 rotate integrally via the

respective splines

16a, 131 a. The cylinder block 4 is axially supported by the static pressure of the working oil between it and the valve plate 19.

A recess 20 is formed between the axial center of the through hole 16 and the end 4a on the bottom wall 119 side so as to surround the shaft 3. A through hole 25 penetrating the cylinder 4 in the axial direction is formed in a part of the inner wall surface between the axial center of the through hole 16 and a portion closer to the front flange 10. In the recess 20, a spring 23 and

retainers

24a, 24b discussed later are housed. A coupling member 26, which will be described later, is accommodated in the through hole 25, and the coupling member 26 is movable in the axial direction.

A plurality of cylinder holes (an example of a cylinder chamber in the claims) 17 are formed in the cylinder block 4 so as to surround the shaft 3. The plurality of cylinder holes 17 are arranged at equal intervals in the circumferential direction on a predetermined pitch circle concentric with the center axis C. The cylinder hole 17 is formed in a bottomed cylindrical shape extending in the axial direction. The portion of the cylinder hole 17 on the front flange 10 side is opened, and the portion of the cylinder hole 17 on the bottom wall 119 side is closed. An outer peripheral side communication hole 18a or an inner peripheral side communication hole 18b for communicating the cylinder holes 17 with the outside of the cylinder block 4 is formed in the end portion 4a of the cylinder block 4 at a position corresponding to each cylinder hole 17.

< valve plate >

Fig. 4 is a view schematically showing an end surface (1 st end surface) 19A of the valve plate 19 of the pump unit 110 on the cylinder block 4 side. Fig. 5 is a view schematically showing an end surface (2 nd end surface) 19B of the valve plate 19 of the pump unit 110 on the side opposite to the cylinder block 4 (bottom wall 119 side). Fig. 6 is a view schematically showing a cross section of the cylinder block 4, the valve plate 19, and the bottom wall 119 of the housing main body 9 of the pump unit 110.

As shown in fig. 2 and 4 to 6, the disc-shaped valve plate 19 is disposed between an end face (an example of an end face of the cylinder block in the claims) 4A of the end portion 4A of the cylinder block 4 and an inner surface 119a of the bottom wall 119 of the housing main body 9. The valve plate 19 is fixed to a bottom wall 119 of the housing main body 9. The valve plate 19 is stationary with respect to the main casing 2 (casing main body 9) even when the cylinder block 4 and the shaft 3 rotate about the center axis C.

The valve plate 19 is formed with a supply port 19a that communicates with each outer peripheral side communication hole 18a and each inner peripheral side communication hole 18b of the cylinder block 4 so as to penetrate through the valve plate 19 in the thickness direction. The supply port 19a is formed in an arc-shaped elongated hole having an outer shape within a predetermined angular range around the center axis C, for example.

Each cylinder hole 17 and the 1 st communication path 124 formed in the housing main body 9 are connected to and communicated with each other via the supply port 19a of the valve plate 19 and the outer peripheral side communication hole 18a or the inner peripheral side communication hole 18b of the cylinder block 4.

The valve plate 19 is provided with: a plurality of outer peripheral discharge ports 19b communicating with the outer peripheral communication holes 18a of the cylinder 4; and a plurality of inner peripheral side discharge ports 19c communicating with the inner peripheral side communication holes 18b of the cylinder 4 and located radially inward of the outer peripheral side discharge ports 19 b. The communication holes 18a and 18b are formed to penetrate through the valve plate 19 in the thickness direction. The outer shape of each of the outer-peripheral discharge port 19b and the inner-peripheral discharge port 19C is formed as an arc-shaped elongated hole within a predetermined angular range around the center axis C, for example.

The plurality of outer peripheral side discharge ports 19b are formed on the 1 st pitch circle concentric with the central axis C on the 1 st end surface (an example of the 1 st end surface in claims) 19A. The plurality of outer peripheral side discharge ports 19b are formed so as to communicate with an arc-shaped outer peripheral side recess (an example of a discharge port and an outer peripheral side discharge port in the claims) 191 formed in the 1 st pitch circle on the 1 st end surface 19A.

The plurality of inner peripheral side discharge ports 19C are formed on the 1 st end surface 19A on the 2 nd pitch circle smaller than the 1 st pitch circle concentric with the center axis C. The plurality of inner peripheral side discharge ports 19c are formed so as to communicate with an arc-shaped inner peripheral concave portion (an example of a discharge port and an inner peripheral side discharge port in claims) 192 formed on the 2 nd pitch circle on the 1 st end surface 19A.

The diameter of the 1 st pitch circle is a size closer to the diameter of a predetermined pitch circle corresponding to the plurality of cylinder bores 17 of the cylinder block 4 than the diameter of the 2 nd pitch circle. The diameter of the 1 st pitch circle is set to be slightly smaller than the diameter of a predetermined pitch circle corresponding to the plurality of cylinder holes 17, for example.

Each cylinder hole 17 and the 3 rd communication path 128a formed in the housing main body 9 are connected to and communicate with the outer peripheral communication hole 18a of the cylinder block 4 via the outer peripheral discharge port 19b of the valve plate 19.

Each cylinder hole 17 and the 4 th communication path 128b formed in the housing main body 9 are connected to and communicate with the inner peripheral communication hole 18b of the cylinder block 4 via the inner peripheral discharge port 19c of the valve plate 19.

A pressure acting portion (an example of a pressure acting chamber in the claims) 193, on which the pressure of the hydraulic oil from the inner peripheral side discharge port 19c and the inner peripheral side concave portion 192 acts, is formed on the 2 nd end surface (an example of the 2 nd end surface in the claims) 19B of the valve plate 19. The 2 nd end surface 19B is a surface opposed to the inner surface 119a of the case main body 9. The pressure acting portion 193 includes a pressure receiving recessed portion (an example of a recess in the claims) 193A formed in the 2 nd end surface 19B. A passage 194 for working oil (an example of the passage in the claims) that communicates between the inner peripheral side concave portion 192 and the pressure receiving concave portion 193A is formed in the valve plate 19.

The pressure acting portion 193 is provided on the 2 nd end surface 19B side in a region opposed to a region on a straight line (an example of a straight line in the claims) La connecting a pressure acting point (an example of a pressure acting point in the claims) Pa and a separating force acting point (an example of a separating force acting point in the claims) Pb on the 1 st end surface 19A of the valve plate 19.

The pressing force is a force that presses the cylinder block 4 against the valve plate 19 by a piston 21 (details will be described later) housed in each cylinder hole 17 of the cylinder block 4 so as to be slidable in the axial direction. The pressing force is the pressure of the hydraulic fluid acting on the outer peripheral side communication hole 18a and the inner peripheral side communication hole 18b of the cylinder 4. The pressing force is a discharge reaction force of the hydraulic oil acting in a cylinder chamber formed by the cylinder 4 and the piston 21.

The point Pa at which the pressing force acts is, for example, a position that is located in a fan-shaped region (a region hatched with a two-dot chain line in fig. 4) surrounded by two straight lines Lb connecting both ends of the inner peripheral side concave portion 192 in the circumferential direction and the center axis C (an example of a straight line in the claims) and a radially inner peripheral edge of the inner peripheral side concave portion 192, and that is located radially closer to the center axis C and circumferentially closer to a central portion of the inner peripheral side concave portion 192.

The separating force is an oil film reaction force of the hydraulic oil between the end surface 4A of the cylinder block 4 and the 1 st end surface 19A of the valve plate 19, and an oil pressure acting on the end surface 4A of the cylinder block 4 from the supply port 19A and the outer peripheral side discharge port 19b or the inner peripheral side discharge port 19c of the valve plate 19. The point Pb of application of the separating force when the pressure acts on the inner peripheral side discharge port 19C and the inner peripheral side concave portion 192 is, for example, a position located in a fan-shaped region surrounded by a line segment connecting both end portions of the inner peripheral side concave portion 192 in the circumferential direction and the center axis C and located radially and circumferentially closer to the center portion of the inner peripheral side concave portion 192.

The diameter of the 1 st pitch circle corresponding to the outer peripheral side discharge port 19b and the outer peripheral side concave portion 191 of the valve plate 19 is substantially the same as the diameter of the predetermined pitch circle corresponding to the plurality of cylinder holes 17 of the cylinder block 4, and therefore the pressing force and the separating force are substantially balanced in the vicinity of the outer peripheral side discharge port 19b and the outer peripheral side concave portion 191.

On the other hand, the diameter of the 2 nd pitch circle corresponding to the inner peripheral side discharge port 19c and the inner peripheral side concave portion 192 of the valve plate 19 is smaller than the diameter of the predetermined pitch circle corresponding to the plurality of cylinder holes 17 of the cylinder block 4, and therefore, unbalance occurs in the vicinity of the inner peripheral side discharge port 19c and the inner peripheral side concave portion 192 due to a displacement between the point of action of the pressing force and the point of action of the separating force. The pressure acting portion 193 causes an additional force to act on the valve plate 19 by the pressure of the hydraulic oil from the inner peripheral side discharge port 19c and the inner peripheral side concave portion 192, the additional force being for eliminating an imbalance between the pressing force and the separating force of the inner peripheral side discharge port 19c and the inner peripheral side concave portion 192.

The pressure acting portion 193 is provided, for example, in a sector region surrounded by a line segment connecting both end portions in the circumferential direction of the inner circumferential side concave portion 192 and the center axis C. The pressure acting portion 193 is provided, for example, in a region that is offset radially inward with respect to the inner circumferential recessed portion 192 and is located circumferentially closer to the center of the inner circumferential recessed portion 192.

The pressure acting portion 193 is formed in an outer shape, for example, in a circular shape as viewed in the axial direction, a so-called kidney-shaped arc-like oval shape along the inner peripheral side concave portion 192, or the like.

The pressure acting portion 193 is formed to have a magnitude such that, for example, a force generated toward the cylinder block 4 by which reaction forces of the separating force acting on the 1 st end surface 19A of the valve plate 19 are maximally cancelled out each other is not excessive between the 2 nd end surface 19B of the valve plate 19 and the inner surface 119A of the bottom wall 119.

Since the valve plate 19 is fixed to the housing main body 9, each cylinder hole 17 is switched to: a state in which the working oil is supplied from the 1 st suction path 122 via the valve plate 19, and a state in which the working oil is discharged to the 1 st discharge path 123a or the 2 nd discharge path 123 b.

The pistons (an example of a piston in claims) 21 are housed in the respective cylinder holes 17 of the cylinder 4, and rotate so as to revolve around the central axis C of the shaft 3 in accordance with the rotation of the shaft 3 and the cylinder 4.

The end of the piston 21 on the front flange 10 side is provided with a spherical projection 28 integrally formed therewith. A cavity for storing the hydraulic oil in the cylinder hole 17 is formed inside the piston 21. The reciprocating motion of the piston 21 is associated with the supply and discharge of the working oil with respect to the cylinder bore 17.

When the piston 21 is pulled out from the cylinder bore 17, the working oil is supplied from the 1 st suction path 122 into the cylinder bore 17 through the 1 st communication path 124 and the supply port 19a, and the outer peripheral side communication hole 18a or the inner peripheral side communication hole 18 b.

When the piston 21 enters the cylinder bore 17, the hydraulic oil is discharged from the inside of the cylinder bore 17 through the outer peripheral side communication hole 18a, the outer peripheral side discharge port 19b, the 3 rd communication path 128a, and the 1 st discharge path 123a, or from the inside of the cylinder bore 17 through the inner peripheral side communication hole 18b, the inner peripheral side discharge port 19c, the 4 th communication path 128b, and the 2 nd discharge path 123 b.

The spring 23 accommodated in the recess 20 of the cylinder 4 is, for example, a coil spring. The spring 23 is compressed between two

holders

24a, 24b housed in the recess 20. The spring 23 generates a biasing force in an extending direction by the elastic force. The biasing force of the spring 23 is transmitted to the coupling member 26 via one holder 24b of the two

holders

24a, 24 b. The biasing force of the spring 23 is transmitted to the pressing member 27 via the coupling member 26. The pressing member 27 is fitted to the outer peripheral surface of the rotary shaft main body 131 at a position closer to the front flange 10 than the connecting member 26.

The swash plate 5 is provided on an inner surface 10a of the front flange 10 on the housing main body 9 side. The swash plate 5 is provided to be tiltable with respect to the front flange 10. The swash plate 5 is inclined with respect to the front flange 10, thereby restricting displacement of each piston 21 in the direction along the axial direction. A through hole 32 through which the shaft 3 can pass is formed in the radial center of the swash plate 5. The swash plate 5 includes a flat sliding surface 5a on the cylinder block 4 side.

A plurality of shoes 22 movable on the sliding surface 5a are attached to the convex portion 28 of the piston 21. A spherical recess 22a is formed in a surface of the shoe 22 on the side of receiving the projection 28 so as to correspond to the shape of the projection 28. The convex portion 28 of the piston 21 is fitted into the inner wall surface of the concave portion 22 a. The shoe 22 is coupled to the convex portion 28 of the piston 21 so as to be rotatable with respect to the convex portion 28 of the piston 21.

The shoe holding member 29 integrally holds each shoe 22. The pressing member 27 contacts the shoe holding member 29 to press the shoe holding member 29 toward the swash plate 5. The shoe 22 moves so as to follow the sliding surface 5a of the swash plate 5. The inclination angle of the swash plate 5 is controlled by an actuator not shown.

< Gear Pump >

The gear pump 111 includes a gear housing 141, and a drive gear and a driven gear, which are not shown.

The gear housing 141 having a rectangular parallelepiped shape is disposed on the outer surface 119b of the bottom wall 119 of the main housing 2. A 2 nd suction path 144 communicating with the 2 nd communication path 125 of the main casing 2 is formed in a wall surface 141a of the gear casing 141 overlapping the main casing 2. The 2 nd suction path 144 communicates the inside and outside of the wall surface 141a of the gear housing 141.

A coupling through-hole 149 is formed in a wall surface 141a of the gear housing 141 at a position corresponding to the rotation shaft through-hole 121 of the main housing 2. The end of the coupling 136 on the gear pump 111 side protrudes into the gear housing 141 through the coupling through hole 149.

The 1 st side wall surface 141b of the gear housing 141 faces in the same direction as the 1 st side surface 119c of the main housing 2 in which the suction port 122a is formed. The 2 nd side wall surface 141c faces in the same direction as the 2 nd side surface 119d of the main casing 2 where the discharge ports of the

discharge paths

123a and 123b are formed.

A 3 rd discharge path, not shown, is formed on the 2 nd side wall surface 141c of the gear housing 141. The discharge port of the 3 rd discharge path opens at the 2 nd sidewall surface 141 c. The discharge port of the 3 rd discharge path of the gear housing 141 and the discharge ports of the

discharge paths

123a and 123b of the main housing 2 are formed on the 2 nd side wall surface 141c and the 2 nd side surface 119d facing the same direction.

The drive gear and the driven gear are rotatably supported in the gear housing 141 and mesh with each other. The drive gear is coupled to the coupling 136 protruding from the main casing 2 through the coupling through hole 149. The rotational force of the shaft 3 of the main pump 1 is transmitted to the drive gear via the coupling 136. The driven gear is meshed with the drive gear, and therefore, rotates in synchronization with the drive gear.

< action of Pump Unit >

Next, the operation of the pump unit 110 will be described.

First, the operation of the main pump 1 will be described.

The main pump 1 outputs a driving force generated based on discharge of the hydraulic oil from the cylinder bore 17 and supply of the hydraulic oil to the cylinder bore 17.

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

The shoes 22 attached to the convex portions 28 of the pistons 21 are pressed against the sliding surface 5a of the swash plate 5 so as to appropriately follow the sliding surface 5a of the swash plate 5 regardless of the inclination angle of the swash plate 5 by the biasing force of the spring 23. 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 pressing member 27 applies a pressure to press the shoes 22 toward the swash plate 5 via the shoe holding member 29. Even if the inclination angle of the swash plate 5 changes, the shoes 22 follow the inclination of the swash plate 5 and are pressed against the sliding surface 5a so as to appropriately follow the sliding surface 5 a.

When the piston 21 rotates so as to revolve around the central axis C of the shaft 3 in accordance with the rotation of the cylinder 4, each shoe 22 moves on the sliding surface 5a of the swash plate 5 while rotating around the central axis C of the shaft 3. Each piston 21 reciprocates slidably in the axial direction in each cylinder bore 17. The swash plate 5 restricts displacement of each piston 21 in the direction along the axial direction. In accordance with the reciprocating operation of the piston 21, the hydraulic oil is discharged from some of the cylinder bores 17 through the 1 st discharge path 123a or the 2 nd discharge path 123b, and is sucked into another cylinder bore (an example of another cylinder chamber in the claims) 17 through the 1 st suction path 122.

When the inclination angle of the swash plate 5 (sliding surface 5a) changes, the stroke (moving distance) of the reciprocating motion of the piston 21 changes. The larger the inclination angle of the swash plate 5, the larger the supply amount and discharge amount of the hydraulic oil to the cylinder bores 17, which are generated as the pistons 21 reciprocate. The smaller the inclination angle of the swash plate 5, the smaller the supply and discharge amounts of the hydraulic oil to and from the cylinder bores 17, which are generated as the pistons 21 reciprocate. When the inclination angle of the swash plate 5 is zero, the pistons 21 do not reciprocate even if the pistons 21 rotate to revolve around the central axis C of the shaft 3. When the inclination angle of the swash plate 5 is zero, the discharge amount of the hydraulic oil from each cylinder bore 17 is also zero.

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

The drive gear of the gear pump 111 is coupled to the shaft 3 of the main pump 1 via a coupling 136, and therefore rotates integrally with the shaft 3. The driven gear that meshes with the drive gear also rotates in synchronization with the drive gear. The working oil flowing through the 1 st suction path 122 is sucked into the 2 nd suction path 144 through the 2 nd communication path 125 of the main casing 2. The working oil flows between each gear and the inner surface of the gear case 141 to the 3 rd discharge path side. The working oil is discharged through the 3 rd discharge port on the 3 rd discharge path side.

In the above-described embodiment, the pressure acting portion 193, on which the pressure of the hydraulic oil from the inner peripheral side discharge port 19c and the inner peripheral side concave portion 192 acts, is provided on the 2 nd end surface 19B of the valve plate 19 on the bottom wall 119 side. Thus, even when the separating force generated by the pressure of the hydraulic oil between the end surface 4A of the cylinder block 4 and the 1 st end surface 19A of the valve plate 19 increases, the pressure acts in the opposite direction to the reaction force of the separating force acting on the valve plate 19, and the deformation of the valve plate 19 can be suppressed.

Fig. 7 is a graph showing an example of the amount of deformation of the valve plate 19 according to the radial position in the pump unit 110 of the above-described embodiment and comparative example.

As shown in fig. 7, consider that: in the comparative example in which the pressure acting portion 193 is omitted from the above-described embodiment, the valve plate 19 is deformed so as to be deformed in a convex shape toward the bottom wall 119 due to the reaction force caused by the separating force. In contrast, it is believed that: in the above-described embodiment, the force in the direction opposite to the reaction force of the separating force acts on the pressure-acting portion 193, so that the deformation of the valve plate 19 is suppressed.

The pressure acting portion 193 is provided in a corresponding region on a straight line La that connects the point of action Pa of the pressing force and the point of action Pb of the pressure when the pressure acts on the inner peripheral side discharge port 19c and the inner peripheral side concave portion 192. This makes it possible to appropriately cancel the imbalance of the biasing force due to the positional difference between the pressing force application point Pa and the separating force application point Pb by the pressure from the pressure application unit 193.

Further, since the pressure acting portion 193 includes the pressure receiving recessed portion 193A formed in the 2 nd end surface 19B of the valve plate 19, the working oil can be accumulated in the pressure receiving recessed portion 193A, and the pressure can be stably applied in the direction toward the cylinder block 4.

Further, since the passage 194 that communicates the pressure receiving recessed portion 193A and the inner peripheral recessed portion 192 is provided in the valve plate 19, the pressure from the inner peripheral discharge port 19c and the inner peripheral recessed portion 192 can be applied to the pressure receiving recessed portion 193A with a simple configuration.

In the above-described embodiment, since the pump unit 110 includes the valve plate 19 whose deformation is suppressed, it is possible to suppress a reduction in the life and a reduction in the volumetric efficiency due to wear and the like of the cylinder block 4 and the valve plate 19.

In addition, in the above-described embodiment, since the construction machine 100 includes the pump unit 110, the driving efficiency can be improved.

[ 1 st modification ]

Next, a 1 st modification of the embodiment will be described with reference to fig. 8 and 9. The same forms as those of the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted (the same applies to the following modified examples).

Fig. 8 is a view schematically showing a 1 st end surface 19A of a valve plate 19 on the cylinder block 4 side of a pump unit 110 according to a 1 st modification of the embodiment. Fig. 9 is a view schematically showing a 2 nd end surface 19B of the valve plate 19 on the opposite side of the cylinder block 4 in the pump unit 110 according to the 1 st modification of the embodiment.

In the above-described embodiment, the pressure acting portion 193 includes the pressure receiving recessed portion 193A communicating with the passage 194 in the valve plate 19, but is not limited thereto.

As shown in fig. 8 and 9, a pressure acting portion (an example of a pressure acting chamber according to the claims) 195 of the 1 st modification includes a notch-shaped pressure receiving recessed portion (an example of a notch according to the claims) 195A communicating with the inner peripheral side discharge port 19c on the 2 nd end surface 19B. The outer shape of the pressure receiving recessed portion 195A may be formed in an oval shape extending from the inner peripheral side discharge port 19c as viewed in the axial direction, a trapezoidal shape expanding from the inner peripheral side discharge port 19c toward the tip, or the like, for example.

As described above, in modification 1, the same effects as those of the above embodiment are obtained. In addition, in modification 1, the passage 194 in the valve plate 19 can be omitted as compared with the above-described embodiment, and the structure can be prevented from becoming complicated.

In the above-described embodiment and modification 1, the case where the pressure receiving recessed

portions

193A, 195A constituting the

pressure acting portions

193, 195 communicate with the inner peripheral side discharge port 19c (inner peripheral side recessed portion 192) of the valve plate 19 is described. However, the present invention is not limited to this, and the pressure receiving recessed

portions

193A and 195A constituting the

pressure acting portions

193 and 195 may communicate with the outer peripheral side discharge port 19b (outer peripheral side recessed portion 191) of the valve plate 19.

[ modification 2 ]

Next, a modification 2 of the embodiment will be described with reference to fig. 10.

Fig. 10 is a view schematically showing a cross section of the cylinder block 4, the valve plate 19, and the bottom wall 119 of the housing main body 9 of the pump unit 110 according to modification 2 of the embodiment.

In the above embodiment, the pressure acting portion 193 is provided with the pressure receiving recessed portion 193A in the 2 nd end surface 19B of the valve plate 19, but is not limited thereto.

As shown in fig. 10, the bottom wall 119 of modification 2 includes a piston (an example of another piston in the claims) 196 in which pressure is applied to a virtual pressure application portion 193 set on the 2 nd end surface 19B of the valve plate 19. The position where the piston 196 is disposed serves as a pressure acting portion (an example of another pressure acting chamber in the claims) 293. The position of the virtual pressure acting portion 193 of the valve plate 19 is the same as the position of the pressure acting portion 193 in the above-described embodiment.

The piston 196 is accommodated in a cylinder hole (an example of another cylinder chamber in the claims) 197 formed in the inner surface 119a of the bottom wall 119. A passage 198 communicating with the cylinder hole 197 and the 2 nd discharge path 123b is formed in the bottom wall 119. The piston 196 causes a force toward the cylinder 4 to act on the pressure acting portion 193 due to the pressure from the inner peripheral side discharge port 19c and the inner peripheral side concave portion 192 acting on the cylinder bore 197 via the 2 nd discharge path 123b and the passage 198.

As described above, in modification 2, the same effects as those of the above embodiment are obtained. In addition, in modification 2, as compared with the case where the pressure receiving recessed portion 195A or the like is formed in the valve plate 19, the restriction in layout can be reduced, and the piston 196 can be easily disposed at an appropriate position on the bottom wall 119.

The present invention is not limited to the above-described embodiments, and various modifications may be made to the above-described embodiments without departing from the scope of the present invention.

For example, in the above-described embodiment, the description has been given of the case where the construction machine 100 is a hydraulic excavator. However, the present invention is not limited to this, and various kinds of construction machines can be used.

In the above-described embodiment, the case where the pressure acting portion 193 is provided in the region on the straight line La has been described. However, the pressure application portion 193 is not limited to this, and may be provided corresponding to a region where the maximum load is applied to the valve plate 19, a region where the deformation of the valve plate 19 is the maximum, or the like, depending on a positional difference between the pressing force application point Pa and the separating force application point Pb. Specifically, the pressure acting portion 193 may be provided in a sector-shaped region (a region hatched with a two-dot chain line in fig. 4) surrounded by two straight lines Lb connecting both circumferential ends of either one of the outer circumferential recessed portion 191 and the inner circumferential recessed portion 192 and the central axis C, and the radially inner peripheral edge of the inner circumferential recessed portion 192.

In the present embodiment, both circumferential ends of the outer circumferential recessed portion 191 and the inner circumferential recessed portion 192 are located on the same straight line Lb, but both circumferential ends of the outer circumferential recessed portion 191 and the inner circumferential recessed portion 192 may be located on different straight lines from each other. In this case, it is desirable that the pressure acting portion 193 is provided in a region surrounded by two straight lines Lb connecting both ends in the circumferential direction of either one of the outer peripheral side concave portion 191 and the inner peripheral side concave portion 192 and the central axis C and the radially inner peripheral edge of the inner peripheral side concave portion 192, but it is desirable that the pressure acting portion 193 is provided in a region surrounded by two straight lines Lb connecting both ends in the circumferential direction of the inner peripheral side concave portion 192 and the central axis C and the radially inner peripheral edge of the inner peripheral side concave portion 192.

In the above-described embodiment and modification 1, the case where the main pump 1 includes the

pressure acting portions

193 and 195 provided in the valve plate 19 has been described, and in the above-described modification 2, the case where the main pump 1 includes the pressure acting portion 293 provided in the bottom wall 119 of the casing main body 9 (main casing 2) has been described. However, the main pump 1 is not limited to this, and the

pressure acting portions

193, 195, and 293 may be provided in both the valve plate 19 and the housing main body 9.

Claims

1. A fluid machine is provided with:

a housing;

a cylinder block having a cylinder chamber for accommodating a piston; and

a valve plate located between the housing and an end surface of the cylinder block,

wherein the content of the first and second substances,

the valve plate has a discharge port at a 1 st end surface, the discharge port communicating with a discharge port of a working liquid provided to the housing and communicating with the cylinder chamber in accordance with rotation of the cylinder block,

the valve plate has a pressure acting chamber on which the pressure of the discharge port acts, at a 2 nd end surface opposite to the housing.

2. A fluid machine in which, in a fluid machine,

the fluid machine includes:

a housing;

a cylinder block having a cylinder chamber for accommodating a piston; and

the valve plate has a pressure acting chamber connected to the discharge port by a passage at a 2 nd end surface facing the housing.

3. The fluid machine according to claim 1,

the valve plate has another discharge port communicating with the cylinder chamber in accordance with rotation of the cylinder block.

4. The fluid machine according to claim 2,

5. The fluid machine according to claim 3,

the fluid machine is provided with the pressure acting chamber in a region surrounded by two straight lines connecting both circumferential ends of either one of the discharge port and the other discharge port and a central axis of the cylinder block, and a circumferential edge of the radially inner side of the discharge port.

6. The fluid machine according to claim 4,

7. A fluid machine according to any one of claims 1 to 6,

the fluid machine is provided with the pressure acting chambers in respective regions on a straight line connecting an acting point of the pressing force generated by the piston and an acting point of a deviation force generated due to the pressure of the working fluid at the end surface of the cylinder.

8. A fluid machine according to any one of claims 1 to 6,

the pressure acting chamber is a recess provided in the 2 nd end surface opposite to the housing.

9. A fluid machine according to any one of claims 1 to 6,

the fluid machine is provided with the pressure acting chambers in respective regions on a straight line connecting an acting point of the pressing force generated by the piston and an acting point of a deviation force generated due to the pressure of the working fluid at the end surface of the cylinder,

10. A fluid machine in which, in a fluid machine,

the fluid machine includes:

a cylinder block having a plurality of cylinder chambers for accommodating pistons;

a housing in which a suction port and a discharge port for working fluid are formed;

a valve plate disposed between an end surface of the cylinder block and the housing, the valve plate including: a valve plate suction port that communicates with the suction port and communicates with each of the cylinder chambers in accordance with rotation of the cylinder block; and an inner peripheral side discharge port and an outer peripheral side discharge port that communicate with the discharge port between an end surface of the cylinder block and the housing, and that selectively communicate with each of the cylinder chambers in accordance with rotation of the cylinder block; and

a pressure acting chamber located on an end surface of the valve plate on the housing side, and having: pressure receiving recesses formed in respective regions on a straight line connecting an action point of the pressing force generated by the piston and an action point of a deviation force generated by the pressure of the working fluid between the end surface of the cylinder block and the valve plate; and a passage that communicates either the inner peripheral side discharge port or the outer peripheral side discharge port with the pressure receiving pocket, and the pressure acting chamber acts in a direction in which a pressure of at least either the inner peripheral side discharge port or the outer peripheral side discharge port acts toward the cylinder block side on an end surface of the valve plate on the housing side.

11. A fluid machine in which, in a fluid machine,

the fluid machine includes:

a valve plate disposed on an end surface of the cylinder block, the valve plate having a valve plate suction port, an inner peripheral side discharge port, and an outer peripheral side discharge port for the working fluid that communicates with each of the cylinder chambers in accordance with rotation of the cylinder block; and

a housing disposed on a side opposite to the cylinder block with the valve plate interposed therebetween, and including: a suction port for the working fluid, which communicates with the valve plate suction port; an outlet that communicates with the inner peripheral side discharge port and the outer peripheral side discharge port, respectively; and a pressure acting chamber that acts a pressure of the discharge port on the valve plate in a direction toward the cylinder block side on an end surface of the housing on the valve plate side.

12. The fluid machine according to claim 11,

the fluid machine is provided with the other pressure acting chamber in a region corresponding to a range surrounded by two straight lines connecting both ends in the circumferential direction of either one of the inner peripheral side discharge port and the outer peripheral side discharge port and the central axis of the cylinder block and a radially inner peripheral edge of the inner peripheral side discharge port.

13. The fluid machine according to claim 11,

the other pressure acting chambers are provided in respective regions on a straight line connecting an acting point of the pressing force generated by the piston and an acting point of a deviation due to the pressure of the working fluid at the end surface of the cylinder.

14. The fluid machine according to claim 12,

15. A fluid machine according to any one of claims 11 to 14,

the other pressure acting chamber includes:

another cylinder chamber formed in an end surface of the housing on the valve plate side; and

and another piston which is housed in the other cylinder chamber and applies pressure to the valve plate.

16. A fluid machine in which, in a fluid machine,

the fluid machine includes:

a valve plate disposed on an end surface of the cylinder block, the valve plate having a valve plate suction port, an inner peripheral side discharge port, and an outer peripheral side discharge port for the working fluid that communicates with each of the cylinder chambers in accordance with rotation of the cylinder block;

a housing disposed on a side opposite to the cylinder block with the valve plate interposed therebetween, and including: a suction port for the working fluid, which communicates with the valve plate suction port; an outlet that communicates with the inner peripheral side discharge port and the outer peripheral side discharge port, respectively; and

and a pressure acting chamber that has another piston housed in another cylinder chamber and acts pressure on the valve plate, the other cylinder chamber being formed in a corresponding region on an end surface of the housing on the valve plate side and on a straight line connecting an acting point of the pressing force generated by the piston and an acting point of a separating force generated by the pressure of the working fluid between the end surface of the cylinder block and the valve plate.

17. A construction machine including a vehicle body on which the fluid machine according to any one of claims 11 to 16 is mounted.