CN111561433B

CN111561433B - Fluid pressure rotary device and construction machine

Info

Publication number: CN111561433B
Application number: CN202010032516.XA
Authority: CN
Inventors: 狩野拓广; 小岛健太郎
Original assignee: Nabtesco Corp
Current assignee: Nabtesco Corp
Priority date: 2019-02-13
Filing date: 2020-01-13
Publication date: 2024-03-12
Anticipated expiration: 2040-01-13
Also published as: KR20200099071A; JP2020133423A; CN111561433A; JP7356804B2

Abstract

The invention provides a fluid pressure rotating device and a construction machine. A fluid pressure rotating device (10) is provided with: a housing (20); a cylinder (40) rotatably housed in the housing (20); a piston (50) that is movably supported in a cylinder chamber (41) that is open on one side of the cylinder (40); and a valve plate (60) disposed between the housing (20) and the cylinder (40), wherein a fluid chamber (65) is provided between the valve plate (60) and the housing (20), the valve plate (60) is provided with a flow path (66) communicating with the fluid chamber (65), the flow path (66) is open at a position facing the passage (42), and the passage (42) is open at the other side of the cylinder (40) and communicates with the cylinder chamber (41).

Description

Fluid pressure rotary device and construction machine

Technical Field

The present invention relates to a fluid pressure rotating device and a construction machine provided with the fluid pressure rotating device.

Background

As disclosed in JPH9-287552a, for example, a fluid pressure rotating device such as a fluid motor that outputs rotation by supplying fluid is known. The fluid motor disclosed in JPH9-287552a is configured as an axial piston type device. An axial piston fluid motor has: a housing; a cylinder rotatably housed in the housing; a piston slidably inserted into a cylinder chamber formed in the cylinder; and a valve plate (synchronizing plate) mounted to the housing in a state of being sandwiched between the housing and the cylinder. The valve plate has a pair of fluid ports. One fluid port is connected to a fluid pressure source and the other fluid port is connected to a tank. The cylinder block is formed with a connection port that opens to the valve plate and connects with the cylinder chamber. The connection port is connected to the fluid port in response to rotation of the cylinder body, and forms a fluid pressure source or a flow path between the tank and the cylinder chamber.

By communicating the cylinder chamber with a fluid pressure source, fluid is supplied into the cylinder chamber, and the piston advances in the axial direction with respect to the cylinder body. In addition, by communicating the cylinder chamber with the tank, the fluid can be discharged from the cylinder chamber, and the piston can be retracted in the axial direction. On the other hand, the projecting amount of the piston with respect to the cylinder is controlled according to the rotational position of the cylinder. The fluid motor disclosed in JPH9-287552a is constructed as a swash plate. That is, the swash plate having an inclined surface inclined with respect to the axial direction is disposed opposite to the piston in the axial direction. Thus, the piston driven by the fluid pressure acts on the inclined surface of the swash plate to cause rotation of the cylinder block. As the cylinder rotates, the piston advances or retreats in the axial direction in such a manner that the head of the piston moves along the inclined surface in the rotation of the cylinder.

However, when such a fluid motor is used, the rotation shaft of the cylinder may be bent to tilt the cylinder, and the performance of the fluid motor may be deteriorated. That is, there are cases where the fluid leaks from the gap between the cylinder and the valve plate to reduce the volumetric efficiency of the fluid motor, or where the fluid film between the cylinder and the valve plate is interrupted to increase the friction force acting between the cylinder and the valve plate, and the mechanical efficiency of the fluid motor is reduced.

Disclosure of Invention

The present invention has been made in consideration of such a point, and an object of the present invention is to effectively prevent a decrease in performance of a fluid pressure rotary device caused by tilting of a cylinder.

The fluid pressure rotating device of the present invention comprises:

a housing;

a cylinder rotatably accommodated in the housing;

a piston movably supported in a cylinder chamber opened at one side of the cylinder; and

and a valve plate disposed between the housing and the cylinder block, wherein a fluid chamber is provided between the valve plate and the housing, the valve plate is provided with a flow path communicating with the fluid chamber, the flow path is opened at a position facing the flow path, and the flow path is opened at the other side of the cylinder block and communicates with the cylinder chamber.

In the fluid pressure rotary apparatus of the present invention, it may be,

the flow path communicates with a cylinder chamber where the piston is located at a dead point via the passage.

The fluid pressure rotating device according to the present invention may further include an auxiliary piston disposed in the fluid chamber.

In the fluid pressure rotary apparatus of the present invention, it may be,

the fluid chamber is formed in the valve plate.

The construction machine according to the present invention includes the fluid pressure rotating device described above.

According to the present invention, the degradation of the performance of the fluid pressure rotating device caused by the toppling of the cylinder can be effectively prevented.

Drawings

Fig. 1 is a view for explaining an embodiment of the present invention, and is a schematic external view showing a configuration example of a hydraulic excavator.

Fig. 2 is a longitudinal sectional view showing the fluid motor.

Fig. 3 is a plan view showing one side surface of the valve plate.

Fig. 4 is a plan view showing the other side surface of the valve plate.

Fig. 5 is a plan view of the housing cover from one side in the axial direction.

Fig. 6 is an enlarged partial cross-sectional view of the fluid motor shown in fig. 2, and is a diagram showing the fluid chamber and the flow path.

Fig. 7 is a view corresponding to fig. 6, and is a view for explaining the operation of the valve plate.

Fig. 8 is a view corresponding to fig. 7, and is a view for explaining the difference in the pouring angle of the valve plate caused by the difference in the position of the fluid chamber.

Fig. 9 is a view corresponding to fig. 7, and is a view for explaining the difference in the pouring angle of the valve plate caused by the difference in the position of the fluid chamber.

Detailed Description

An embodiment of the present invention will be described below with reference to the drawings. For easy understanding, elements shown in the drawings may include elements whose dimensions and scales are different from those of actual dimensions and scales.

The fluid pressure rotary device 10 described below functions as an axial piston type device. In the illustrated example, the fluid pressure rotating device 10 is configured as a fluid motor, and outputs rotation by supplying fluid. More specifically, the illustrated fluid motor 10 is configured as a swash plate type fluid motor.

In the following, a case will be described in which the fluid motor 10 is used as a motor for the swing device 10a or the traveling devices 10b and 10c of the hydraulic excavator 1.

First, the hydraulic excavator 1 will be described. Fig. 1 is a schematic external view showing a configuration example of the hydraulic excavator 1. In general, the hydraulic excavator 1 includes: a lower frame 2 provided with crawler tracks; an upper frame 3 rotatably provided with respect to the lower frame 2; a boom 4 mounted to the upper frame 3; an arm 5 attached to the boom 4; and a bucket 6 attached to the arm 5. The hydraulic cylinders 4a, 5a, 6a are actuators for the boom, the arm, and the bucket, and drive the boom 4, the arm 5, and the bucket 6, respectively. In addition, when the upper frame 3 is rotated, the rotational driving force from the rotating device 10a is transmitted to the upper frame 3. When the hydraulic excavator 1 is driven, the rotational driving force from the driving devices 10b and 10c is transmitted to the crawler belt of the lower frame 2.

Next, the fluid motor 10 will be described. Fig. 2 is a longitudinal sectional view of the fluid motor 10. As shown in fig. 2, the fluid motor 10 illustrated as a swash plate type has: the casing 20, the shaft member 30, the cylinder block 40, the piston 50, the valve plate (synchronizing plate) 60, and the swash plate 70 are main components. The respective components will be described below.

The housing 20 has a housing main body 21 and a housing cover 22 fixed to the housing main body 21. The case main body 21 is formed in a substantially cylindrical shape with one end closed and the other end open. The case lid 22 is fixed to the case main body 21 with a fastener such as a bolt so as to close the opening of the case main body 21. The housing 20 has a housing space S formed therein. The cylinder block 40, the piston 50, the valve plate 60, and the swash plate 70 are disposed in the accommodation space S.

The shaft member 30 is rotatably held by the housing 20. A pair of bearings 31 is provided in the housing 20. The shaft member 30 is rotatable with the bearing 31 about its central axis as the rotation axis RA. One end 30a of the shaft member 30 extends out toward the housing 20 through a through hole provided to the housing 20. A seal member 32 is provided between the housing 20 and the shaft member 30 at a portion where the shaft member 30 penetrates the housing 20, so that fluid, such as lubricating oil, is prevented from flowing out of the housing 20. The portion 30a of the shaft member 30 extending from the housing 20 is connected to an external device such as a decelerator. That is, the shaft member 30 functions as an output element that outputs rotation.

Hereinafter, a direction parallel to the rotation axis RA is referred to as an axial direction AD, a circumferential direction around the rotation axis RA is referred to as a circumferential direction CD, and a direction perpendicular to the rotation axis RA is referred to as a radial direction RD. The side of the end portion 30a of the shaft member 30 located outside the housing 20 is referred to as one side in the axial direction AD, and the side of the end portion of the shaft member 30 located inside the housing 20 is referred to as the other side in the axial direction AD.

Next, the cylinder 40 will be described. The cylinder 40 has a cylindrical or columnar shape disposed centering on the rotation axis RA. The cylinder 40 is penetrated by the shaft member 30. The cylinder block 40 is fixed relative to the shaft member 30. Thus, the cylinder block 40 can rotate around the rotation axis RA in synchronization with the shaft member 30.

The cylinder block 40 has a plurality of cylinder chambers 41 formed therein. The plurality of cylinder chambers 41 are arranged at equal intervals along the circumferential direction CD centered on the rotation axis RA. The cylinder chambers 41 are provided along the rotation axis RA, and are provided in the axial direction AD parallel to the rotation axis RA. Each cylinder chamber 41 is open on one side in the axial direction AD. In addition, a passage (connection port) 42 is formed corresponding to each cylinder chamber 41. The connection port 42 opens the cylinder chamber 41 on the other side in the axial direction AD.

A piston 50 is provided corresponding to each cylinder chamber 41. A portion of each piston 50 is disposed within the cylinder chamber 41. Each piston 50 extends from the corresponding cylinder chamber 41 to one side in the axial direction AD. The piston 50 is movable in the axial direction AD with respect to the cylinder 40. That is, the piston 50 can advance to one side in the axial direction AD to expand the volume of the cylinder chamber 41. The piston 50 can retract to the other side in the axial direction AD to reduce the volume of the cylinder chamber 41.

The swash plate 70 is held by the housing 20. The swash plate 70 is disposed opposite the cylinder block 40 and the pistons 50 from one side in the axial direction AD. The shaft member 30 penetrates the swash plate 70. The swash plate 70 has a slope 71 inclined with respect to a plane perpendicular to the axial direction AD. The inclined surface 71 is opposed to the cylinder 40 and the piston 50. A shoe 73 is provided on the inclined surface 71 of the swash plate 70. The shoe 73 holds the head of the piston 50. As a specific configuration, a head portion which is one side end of the piston 50 is formed in a spherical shape. The shoe 73 has a hole capable of accommodating substantially half of the spherical head.

The shoe 73 holding the head of the piston 50 can slide on the inclined surface 71 of the swash plate 70. When fluid is supplied into the cylinder chamber 41, the piston 50 advances toward the swash plate 70 with respect to the cylinder block 40. At this time, the cylinder block 40 holding the piston 50 rotates and the piston 50 moves from the thick portion 70a to the thin portion 70b of the swash plate 70. When the fluid is discharged from the cylinder chamber 41, the piston 50 retreats into the cylinder 40. At this time, the cylinder block 40 holding the piston 50 rotates and the piston 50 moves from the thin portion 70b of the swash plate 70 to the thick portion 70 a.

The fluid motor 10 also has a retaining plate 34 disposed within the housing 20. The holding plate 34 is a ring-shaped and plate-shaped member. The holding plate 34 is penetrated by the shaft member 30 and supported by the shaft member 30. The portion 30b of the shaft member 30 supporting the holding plate 34 is formed in a curved surface shape. Accordingly, the holding plate 34 can change orientation in a state of being supported to the shaft member 30. As shown in fig. 1, the plate-like holding plate 34 is inclined so as to follow the inclined surface 71 of the inclined plate 70. And, the holding plate 34 is in contact with all the shoes 73 from the other side in the axial direction AD.

A biasing member 35, which is a spring or the like, is provided between the shaft member 30 and the holding plate 34. The holding plate 34 is biased to one side in the axial direction AD by a biasing member 35. As a result, the retaining plate 34 can press the shoe 73 and the piston 50 against the inclined surface 71 of the swash plate 70. The shaft member 30 is biased toward the other side in the axial direction AD by the biasing member 35 together with the cylinder 40. As a result, the cylinder block 40 is pressed against the valve plate 60. As described above, the cylinder block 40 rotates together with the shaft member 30, and therefore, the surface of the cylinder block 40 facing the valve plate 60 constitutes the sliding surface 40a.

The valve plate 60 is located between the cylinder block 40 and the housing 20 at the other side of the cylinder block 40 in the axial direction AD. The valve plate 60 is held in a non-rotatable manner by a fixing member such as a pin to the housing cover 22. The valve plate 60 is formed in a ring shape and a plate shape. The valve plate 60 has a through hole at its center. The shaft member 30 passes through the through hole and penetrates the valve plate 60. As described above, the cylinder block 40 is brought into contact with the valve plate 60 by the urging member 35. The valve plate 60 is in contact with the housing cover 22 of the housing 20. That is, one side 60a of the valve plate 60 facing one side is in contact with the cylinder block 40, and the other side 60b of the valve plate 60 facing the other side is in contact with the housing cover 22 of the housing 20.

Here, fig. 3 shows the valve plate 60 from the side face 60 a. In addition, fig. 4 shows the valve plate 60 from the other side 60b side. In fig. 3 and 4, the 1 st reference position p1 is a position overlapping the piston 50 that enters the cylinder chamber 41 to the maximum extent in the axial direction AD. In other words, the 1 st reference position p1 is a position obtained by projecting the center position of the piston 50 located at the top dead center in the axial direction AD. On the other hand, in fig. 2, the 2 nd reference position p2 is a position overlapping in the axial direction AD with the piston 50 (piston 50 located at the bottom dead center) protruding from the cylinder chamber 41 to the greatest extent.

As shown in fig. 3 and 4, the 1 st fluid port 61a and the 2 nd fluid port 61b are formed in the valve plate 60. The 1 st fluid port 61a and the 2 nd fluid port 61b penetrate the valve plate 60. The 1 st fluid port 61a and the 2 nd fluid port 61b extend along an arc centered on the rotation axis RA. The 1 st fluid port 61a and the 2 nd fluid port 61b form openings extending in the circumferential direction CD at one side 60a and the other side 60 b.

The 1 st fluid port 61a and the 2 nd fluid port 61b are provided in regions on opposite sides of each other with a straight line vl connecting the 1 st reference position p1 and the 2 nd reference position p2 interposed therebetween. The 1 st fluid port 61a and the 2 nd fluid port 61b have a point-symmetrical structure (arrangement and shape) centered on the rotation axis RA in the example shown in fig. 3 and 4. The connection port 42 of the cylinder 40 moves the positions facing the 1 st fluid port 61a and the 2 nd fluid port 61b in the axial direction AD with the rotation of the cylinder 40. Thereby, a fluid flow path is formed between the cylinder chamber 41 and the 1 st fluid flow path fp1 or the 2 nd fluid flow path fp2 discussed later via the 1 st fluid port 61a or the 2 nd fluid port 61b.

Fig. 5 shows the housing cover 22 from one side in the axial direction AD. Namely, the surface 24 of the housing cover 22 facing the valve plate 60 is shown. The 1 st fluid flow path fp1 and the 2 nd fluid flow path fp2 are formed in the housing 20. The 1 st fluid flow path fp1 and the 2 nd fluid flow path fp2 are open to the housing cover 22 in the example shown in fig. 5. The 1 st fluid flow path fp1 of the housing 20 is always connected to the 1 st fluid port 61a of the valve plate 60. The 2 nd fluid flow path fp2 of the housing 20 is always connected to the 2 nd fluid port 61b of the valve plate 60. The 1 st fluid flow fp1 is connected to one of a fluid pressure source such as a fluid pump and a tank, and the 2 nd fluid flow fp2 is connected to the other of the fluid pressure source such as the fluid pump and the tank. The connection between the 1 st fluid flow path fp1 and the 2 nd fluid flow path fp2 and the fluid pressure source and the tank can be switched by a switching valve, not shown. That is, one of the 1 st fluid flow path fp1 and the 2 nd fluid flow path fp2 is connected to the fluid pressure source, and is on the high pressure (supply) side. The other of the 1 st fluid flow path fp1 and the 2 nd fluid flow path fp2 is connected to the tank and is on the low pressure (discharge) side. The switching valve may block the 1 st fluid flow path fp1 and the 2 nd fluid flow path fp2 from both the fluid pressure source and the tank to be neutral.

When the 1 st fluid flow fp1 is connected to the fluid pressure source and becomes the high pressure side, and the 2 nd fluid flow fp2 is connected to the tank and becomes the low pressure side, the cylinder chamber 41 located on the side of the straight line vl (right side in fig. 3) is connected to the 1 st fluid flow fp1 via the connection port 42 and the 1 st fluid port 61a, and fluid is supplied. Thus, the piston 50 located on the side of the straight line vl in fig. 3 advances toward the side of the axial direction AD with respect to the cylinder 40. At this time, the cylinder 40 rotates in the direction of arrow Ar in fig. 3 so that the advancing piston 50 is directed in the circumferential direction CD toward the 2 nd reference position p2 which can protrude most with respect to the cylinder 40. On the other hand, the piston 50 located on the other side (left side in fig. 3) of the straight line vl is directed to the 1 st reference position p1 in the circumferential direction CD with rotation of the cylinder 40 in the direction of the arrow Ar. At this time, the piston 50 retreats toward the cylinder 40 side, and thus the fluid in the cylinder chamber 41 is discharged to the 2 nd fluid flow path fp2 via the connection port 42 and the 2 nd fluid port 61b.

On the other hand, if the 1 st fluid flow path fp1 is connected to the tank and becomes the low pressure side, and the 2 nd fluid flow path fp2 is connected to the fluid pressure source and becomes the high pressure side, the fluid is supplied to the cylinder chamber 41 located on the other side (left side in fig. 3) of the straight line vl. As a result, the piston 50 located on the other side of the straight line vl advances toward one side in the axial direction AD with respect to the cylinder 40, and the cylinder 40 rotates in the reverse direction of the arrow Ar in fig. 3.

The fluid to be supplied and discharged between the fluid pressure source and the fluid motor 10 and between the tank and the fluid motor 10 is not particularly limited, but may be typically oil. The oil functions as working oil for driving the piston 50 and also functions as lubricating oil for smoothing the operation of the cylinder 40 and the piston 50.

When the 1 st fluid flow path fp1 is supplied with the high-pressure fluid, the 1 st fluid port 61a becomes a high-pressure side fluid port, and the cylinder 40 rotates in the direction of arrow Ar. As shown in fig. 3, a 1 st slit 62a connected to the rotation direction front end hf1 of the 1 st fluid port 61a on the high pressure side is formed in the one side surface 60a of the valve plate 60. On the other hand, when the high-pressure fluid is supplied to the 2 nd fluid flow path fp2, the 2 nd fluid port 61b becomes a high-pressure side fluid port, and the cylinder 40 rotates in the reverse direction of the arrow Ar. As shown in fig. 3, a 2 nd slit 62b connected to the rotation direction front end hf2 of the 2 nd fluid port 61b on the high pressure side is formed in one side surface 60a of the valve plate 60.

Here, the front end portions of the fluid ports 61a and 61b in the rotation direction are end portions of the fluid ports 61a and 61b having both end portions in the longitudinal direction, which first face the connection ports 42 of the cylinder chambers 41 and are connected to the connection ports 42 of the cylinder chambers 41, in response to the rotation of the cylinder block 40. That is, the 1 st slit 62a is connected to the end of the 1 st fluid port 61a on the side close to the 1 st reference position p1, and the 2 nd slit 62b is connected to the end of the 2 nd fluid port 61b on the side close to the 1 st reference position p1.

The 1 st slit 62a and the 2 nd slit 62b are arranged on the same circumference as the 1 st fluid port 61a and the 2 nd fluid port 61b, and extend in the circumferential direction CD. Accordingly, as the cylinder block 40 rotates, the connection port 42 moves at a position facing the 1 st cutout groove 62a and the 2 nd cutout groove 62b. By the 1 st slit 62a and the 2 nd slit 62b, the connection port 42 of the cylinder chamber 41 overlaps with the high-pressure-side fluid ports 61a, 61b due to the rotation of the cylinder block 40, and immediately before the high-pressure fluid flows into the cylinder chamber 41 in large amounts from the high-pressure-side fluid ports 61a, 61b, the high-pressure fluid is caused to flow into the cylinder chamber 41 while gradually increasing the flow rate through the slits 62a, 62b. This can alleviate abrupt and large pressure changes in the cylinder chamber 41 caused by the inflow of the high-pressure fluid, thereby reducing noise.

In the example shown in fig. 3, a 4 th slit 62d connected to the rotation direction front end lf4 of the 2 nd fluid port 61b in the case of the low pressure side and a 3 rd slit 62c connected to the rotation direction front end lf3 of the 1 st fluid port 61a in the case of the low pressure side are formed in one side surface 60a of the valve plate 60. The 3 rd notch 62c is connected to the end lf3 of the 1 st fluid port 61a on the side close to the 2 nd reference position p2, and the 4 th notch 62d is connected to the end lf4 of the 2 nd fluid port 61b on the side close to the 2 nd reference position p2. The 3 rd and 4 th slits 62c and 62d are also arranged on the same circumference as the 1 st and 2 nd fluid ports 61a and 61b, and extend in the circumferential direction CD. Thus, the connection port 42 moves at a position facing the 3 rd and 4 th slits 62c and 62 d.

By the 3 rd and 4 th slits 62c and 62d, the connection port 42 of the cylinder chamber 41 overlaps with the low-pressure side fluid ports 61a and 61b due to the rotation of the cylinder block 40, and immediately before the fluid is discharged from the low-pressure side fluid ports 61a and 61b to the cylinder chamber 41 in large amounts, the fluid can be discharged from the cylinder chamber 41 via the slits 62c and 62d while gradually increasing the flow rate, whereby noise can be reduced.

Next, the operation of the fluid motor 10 configured as described above will be described.

When the 1 st fluid flow path fp1 and the 1 st fluid port 61a are connected to the fluid pressure source to be on the high pressure side and the 2 nd fluid flow path fp2 and the 2 nd fluid port 61b are connected to the tank to be on the low pressure side by the operation of the switching valve not shown, the cylinder 40 rotates in the direction of arrow Ar in fig. 3 as described above. At this time, fluid is supplied to the cylinder chamber 41 located on the side of the straight line vl (right side in fig. 3) to advance the piston 50 from the cylinder chamber 41 to the side of the axial direction AD. The shoe 73 holding the head of the piston 50 is moved in the circumferential direction CD toward the 2 nd reference position p2 while being in sliding contact with the inclined surface 71 in accordance with the rotation of the cylinder 40. The fluid is discharged from the cylinder chamber 41 located on the other side (left side in fig. 3) of the straight line vl, and the piston 50 retreats toward the other side in the axial direction AD in the cylinder chamber 41. The shoe 73 holding the head of the piston 50 is in sliding contact with the inclined surface 71 as the cylinder 40 rotates, and moves in the circumferential direction CD toward the 1 st reference position p1. As described above, the cylinder 40 rotates together with the shaft member 30 to output the normal rotation from the fluid motor 10.

Next, by an operation of a switching valve, not shown, the 1 st fluid flow path fp1 and the 1 st fluid port 61a are disconnected from the connection to the fluid pressure source, and the 2 nd fluid flow path fp2 and the 2 nd fluid port 61b are disconnected from the connection to the tank. That is, the fluid motor 10 is in the neutral state, and the inflow and outflow of fluid to and from each cylinder chamber 41 is stopped. Thereby, the rotation of the cylinder 40 and the shaft member 30 is stopped, and the rotation output from the fluid motor 10 is stopped.

When the 1 st fluid flow path fp1 and the 1 st fluid port 61a are connected to the tank to be on the low pressure side and the 2 nd fluid flow path fp2 and the 2 nd fluid port 61b are connected to the fluid pressure source to be on the high pressure side by the operation of a switching valve not shown, the cylinder 40 rotates in the reverse direction of the arrow Ar in fig. 3. Thereby, the cylinder 40 rotates together with the shaft member 30, and the fluid motor 10 outputs reverse rotation.

However, during use of the fluid motor 10, the cylinder block 40 may tilt, and a wedge-shaped gap may be formed between the sliding surface 40a of the cylinder block 40 and the valve plate 60. In this case, the cylinder block 40 and the valve plate 60 relatively rotate while being locally pressed in the axial direction AD. Thereby, the friction force acting between the cylinder block 40 and the valve plate 60 increases and the mechanical efficiency of the fluid motor 10 decreases. In addition, the gap between the cylinder block 40 and the valve plate 60 is partially enlarged, and the fluid leaks out of the enlarged gap during rotation of the cylinder block 40. As a result, the volumetric efficiency of the fluid motor 10 decreases.

In order to cope with such a problem, in the present embodiment, a study is made to tilt the valve plate 60 so as to follow the sliding surface 40a of the cylinder block 40 that is tilted. Specifically, as shown in fig. 6, a fluid chamber 65 is provided between the valve plate 60 and the housing 20. The valve plate 60 is provided with a flow path 66 communicating with the fluid chamber 65. The flow path 66 opens the fluid chamber 65 to one side in the axial direction AD. In addition, on one side surface 60a of the valve plate 60, the flow path 66 is opened at a position facing the connection port 42 communicating with the cylinder chamber 41. That is, the flow path 66 opens on the movement locus of the connection port 42. Thereby, the fluid in the cylinder chamber 41 can flow into the fluid chamber 65 via the connection port 42 and the flow path 66. As shown in fig. 7, the valve plate 60 can be tilted so as to follow the sliding surface 40a of the cylinder block 40 by the pressure of the fluid in the fluid chamber 65.

By tilting the valve plate 60 as shown in fig. 7, the local contact between the cylinder block 40 and the valve plate 60 can be alleviated, and the frictional force acting between the cylinder block 40 and the valve plate 60 can be alleviated. Further, the mechanical efficiency of the fluid motor 10 can be improved. In addition, it is possible to suppress formation of a gap between the cylinder block 40 and the valve plate 60 through which fluid leaks, and to suppress a decrease in volumetric efficiency of the fluid motor 10.

In the illustrated example, the fluid chamber 65 is formed in the valve plate 60. More specifically, a recess is formed in the other side surface 60b of the valve plate 60, and the recess functions as a fluid chamber 65. By forming the fluid chamber 65 in the valve plate 60, it is easy to provide the fluid chamber 65 between the valve plate 60 and the housing cover 22. In addition, the alignment between the fluid chamber 65 and the flow path 66 communicating with the fluid chamber 65 can be easily performed. Of course, the fluid chamber 65 may be formed in a place other than the valve plate 60. For example, the fluid chamber 65 may be formed in the housing 20. Specifically, a recess may be formed in the surface 24 of the housing cover 22 facing the valve plate 60, and the recess may function as a fluid chamber. The fluid chamber may be formed by a concave portion formed to face the valve plate 60 and the housing cover 22.

Further, as a result of intensive studies on the cause of the cylinder 40 tilting, it is estimated that the cylinder 40 is tilted due to the following cause.

First, it is considered that the deflection of the shaft member 30 is a cause of the cylinder 40 to topple. For example, when the shaft member 30 is rotated together with the cylinder block 40 in which the high-pressure fluid flows into the cylinder chamber 41, the load applied to the central portion of the shaft member 30 in the axial direction AD increases. Thereby, the shaft member 30 deflects so that the central portion is displaced downward (in the direction from the 1 st reference position p1 toward the 2 nd reference position p 2). As a result, the cylinder block 40 is tilted such that the portion thereof in the vicinity of the 1 st reference position p1 is displaced to one side in the axial direction AD and the portion thereof in the vicinity of the 2 nd reference position p2 is displaced to the other side in the axial direction AD.

Alternatively, it is considered that the disappearance of the lubricating film formed by the fluid between the piston 50 and the cylinder 40 is the cause of the cylinder 40 to topple. The piston 50 is pulled into the cylinder chamber 41 to the maximum extent when it is located at the 1 st reference position p1 in the circumferential direction CD. The piston 50 is also pulled out from the cylinder chamber 41 to the axial direction AD by the holding plate 34 while moving in the circumferential direction CD from the 1 st reference position p1 toward the fluid ports 61a and 61b on the high pressure side. However, until the piston 50 moves to a position facing the cutout grooves 62a, 62b, fluid is not supplied to the cylinder chamber 41 corresponding to the piston 50. Thus, between the piston 50 and the cylinder chamber 41, the lubrication film formed by the fluid is interrupted. As a result, the friction force between the piston 50 and the cylinder chamber 41 increases sharply, and the portion of the cylinder 40 in the vicinity of the 1 st reference position p1 is pulled to one side in the axial direction AD by the operation of the piston 50. As a result, the cylinder block 40 is tilted such that the portion thereof in the vicinity of the 1 st reference position p1 is displaced to one side in the axial direction AD and the portion thereof in the vicinity of the 2 nd reference position p2 is displaced to the other side in the axial direction AD.

In the illustrated example, the fluid chamber 65 is provided in the vicinity of the 1 st reference position p1 in consideration of the above-described cause of the cylinder 40 tilting. In addition, on one side surface 60a of the valve plate 60, a flow path 66 communicating with the fluid chamber 65 is opened at a position facing the connection port 42 of the cylinder chamber 41 located at the 1 st reference position p1 (thus, the cylinder chamber 41 where the piston 50 is located at the top dead center). Thus, the portion of the valve plate 60 in the vicinity of the 1 st reference position p1 is pressed by the pressure of the fluid accommodated in the fluid chamber 65 so as to be displaced to one side in the axial direction AD, and at the same time, the portion of the valve plate 60 in the vicinity of the 2 nd reference position p2 is displaced to the other side in the axial direction AD. That is, the valve plate 60 can be tilted so as to follow the sliding surface 40a of the cylinder block 40 that is tilted as described above. This can alleviate local contact between the cylinder block 40 and the valve plate 60, and reduce friction force acting between the cylinder block 40 and the valve plate 60. As a result, the mechanical efficiency of the fluid motor 10 can be improved. In addition, a gap in which fluid leaks can be suppressed from being formed between the valve plate 60 and the portion of the cylinder block 40 in the vicinity of the 1 st reference position p1. As a result, a decrease in the volumetric efficiency of the fluid motor 10 can be suppressed.

The cylinder block 40 is not limited to being tilted such that a portion thereof in the vicinity of the 1 st reference position p1 is displaced to one side in the axial direction AD and a portion thereof in the vicinity of the 2 nd reference position p2 is displaced to the other side in the axial direction AD. For example, when the shaft member 30 is deflected such that the central portion of the shaft member 30 in the axial direction AD is displaced upward (in the direction from the 2 nd reference position p2 toward the 1 st reference position p 1), the cylinder 40 is tilted such that the portion thereof in the vicinity of the 2 nd reference position p2 is displaced to one side of the axial direction AD and the portion thereof in the vicinity of the 1 st reference position p1 is displaced to the other side of the axial direction AD. In this case, the fluid chamber 65 is provided in the vicinity of the 2 nd reference position p2. The flow path 66 communicating with the fluid chamber 65 is provided on the one side surface 60a of the valve plate 60 so as to open at a position facing the connection port 42 of the cylinder chamber 41 located at the 2 nd reference position p2 (thus, the cylinder chamber 41 where the piston 50 is located at the bottom dead center). Thus, the portion of the valve plate 60 in the vicinity of the 2 nd reference position p2 is pressed by the pressure of the fluid accommodated in the fluid chamber 65 so as to be displaced to one side in the axial direction AD, and at the same time, the portion of the valve plate 60 in the vicinity of the 1 st reference position p1 is displaced to the other side in the axial direction AD. That is, the valve plate 60 can be tilted so as to follow the sliding surface 40a of the cylinder block 40 that is tilted as described above.

Of course, the fluid chamber 65 may be provided in both the vicinity of the 1 st reference position p1 and the vicinity of the 2 nd reference position p2. In this case, the flow path 66 communicating with the fluid chamber 65 located in the vicinity of the 1 st reference position p1 may be provided on the one side surface 60a of the valve plate 60 so as to open at a position facing the connection port 42 of the cylinder chamber 41 located in the 1 st reference position p1. In addition, a flow path 66 communicating with the fluid chamber 65 located in the vicinity of the 2 nd reference position p2 may be provided on one side surface 60a of the valve plate 60 so as to open at a position facing the connection port 42 with the cylinder chamber 41 located in the 2 nd reference position p2.

In the illustrated example, an auxiliary piston 67 is disposed in the fluid chamber 65. Auxiliary piston 67 blocks the gap between fluid chamber 65 and valve plate 60 and housing cover 22. Thus, the escape of fluid from the fluid chamber 65 can be effectively prevented. As a result, the pressure of the fluid flowing into the fluid chamber 65 can be effectively increased, and the valve plate 60 can be effectively pressed.

In the illustrated example, a part of the auxiliary piston 67 is disposed in the fluid chamber 65. The auxiliary piston 67 is movable in the axial direction AD with respect to the fluid chamber 65. Therefore, when fluid flows into the fluid chamber 65, the auxiliary piston 67 moves in the axial direction AD with respect to the fluid chamber 65, and the volume of the fluid chamber 65 is enlarged. At this time, the other end of the auxiliary piston 67 abuts against the housing cover 22, and the valve plate 60 is tilted so that the portion located in the vicinity of the fluid chamber 65 moves to one side in the axial direction AD.

In the examples shown in fig. 4, 6 and 7, as clearly shown in fig. 4, the center of the fluid chamber 65 coincides with the center of the flow path 66 communicating with the fluid chamber 65 in the axial direction AD. By shifting the center of the fluid chamber 65 from the center of the flow path 66, the tilt angle of the valve plate 60 can be adjusted. That is, as shown in fig. 8, by disposing the center of the fluid chamber 65 at a position on the inner side in the radial direction RD in the up-down direction (the direction along the straight line v1 connecting the 1 st reference position and the 2 nd reference position p 2) with respect to the center of the flow path 66, the tilting angle of the valve plate 60 can be increased as compared with the case shown in fig. 7. Further, as shown in fig. 9, by disposing the center of the fluid chamber 65 at a position outside the center of the flow path 66 in the radial direction RD in the up-down direction, the tilting angle of the valve plate 60 can be reduced as compared with the case shown in fig. 7.

In the above-described embodiment, the fluid pressure rotating apparatus 10 is configured as a fluid motor, but the present invention is not limited to this. The fluid pressure rotary device 10 may also be configured as a fluid pump. In this case, the shaft member 30 is rotated by power from a power source such as an engine, and the cylinder 40 is rotated to reciprocate the piston 50. According to the reciprocation of the piston 50, fluid is discharged from a part of the cylinder chambers 41, and the fluid is sucked into the other cylinder chambers 41, thereby realizing a fluid pump. Such a fluid pump can be used as a fluid pressure source for supplying fluid to the hydraulic cylinders 4a, 5a, 6a, the motor for the slewing device 10a, the motor for the traveling devices 10b, 10c, and the like. Of course, the fluid pressure rotary device 10 may be applied to applications other than motors and pumps of construction machines, and the applications thereof are not particularly limited. The construction machine to which the fluid pressure rotating apparatus 10 can be applied is not limited to a hydraulic excavator. The fluid pressure rotating apparatus 10 can be applied to construction machines other than hydraulic excavators.

The fluid pressure rotating apparatus 10 according to the present embodiment described above includes: a housing 20; a cylinder 40 rotatably accommodated in the housing 20; and a piston 50 movably supported in the cylinder chamber 41 opened at one side of the cylinder block 40. The fluid pressure rotating device 10 includes a valve plate 60, the valve plate 60 being disposed between the housing 20 and the cylinder block 40, a fluid chamber 65 being provided between the valve plate 60 and the housing 20, and the valve plate 60 being provided with a flow path 66 communicating with the fluid chamber 65. The flow path 66 is open at a position facing the passage, and the passage is open at the other side of the cylinder 40 and communicates with the cylinder chamber 41.

According to the fluid pressure rotating apparatus 10, when the cylinder block 40 is tilted, the valve plate 60 can be tilted by the pressure of the fluid in the fluid chamber 65. This can alleviate the local contact between the cylinder block 40 and the valve plate 60, and reduce the frictional force acting between the cylinder block 40 and the valve plate 60. As a result, the mechanical efficiency of the fluid pressure rotating apparatus 10 can be improved. In addition, a gap in which fluid leaks can be suppressed from being formed between the cylinder block 40 and the valve plate 60. As a result, a decrease in the volumetric efficiency of the fluid pressure rotating apparatus 10 can be suppressed.

Specifically, the flow path 66 communicates with the cylinder chamber 41 where the piston 50 is positioned at the dead center via the passage 42. This can further alleviate the local contact between the cylinder block 40 and the valve plate 60, and can reduce the frictional force acting between the cylinder block 40 and the valve plate 60 more effectively.

The fluid pressure rotating device 10 of the present embodiment includes an auxiliary piston 67 disposed in the fluid chamber 65. Thereby, the auxiliary piston 67 blocks the gap between the fluid chamber 65 and the valve plate 60, which is in the housing 20 and is poured. Thus, the escape of fluid from the fluid chamber 65 can be effectively prevented. This effectively increases the pressure of the fluid in the fluid chamber 65, and effectively presses the valve plate 60.

In the fluid pressure rotating apparatus 10 of the present embodiment, the fluid chamber 65 is formed in the valve plate 60. Thereby, the fluid chamber 65 can be easily manufactured. In addition, the alignment between the fluid chamber 65 and the flow path 66 communicating with the fluid chamber 65 can be easily performed.

The construction machine 1 of the present embodiment includes the fluid pressure rotating device 10 described above. According to the construction machine 1, when the cylinder 40 of the fluid pressure rotating apparatus 10 is tilted, the valve plate 60 can be tilted by the pressure of the fluid in the fluid chamber 65. This can alleviate the local contact between the cylinder block 40 and the valve plate 60, and reduce the frictional force acting between the cylinder block 40 and the valve plate 60. As a result, the mechanical efficiency of the fluid pressure rotating apparatus 10 can be improved. In addition, a gap in which fluid leaks can be suppressed from being formed between the cylinder block 40 and the valve plate 60. As a result, a decrease in the volumetric efficiency of the fluid pressure rotating apparatus 10 can be suppressed.

The present invention is not limited to the above-described embodiments. For example, various modifications may be applied to the elements of the above-described embodiments. The embodiments of the present invention include the components and/or methods other than those described above. The embodiments of the present invention also include modes that do not include some of the above-described components and/or methods. The effects achieved by the present invention are not limited to the above-described effects, and can also exhibit unique effects corresponding to the specific configurations of the respective embodiments.

Claims

1. A fluid pressure rotary device, wherein,

the fluid pressure rotating device is provided with:

a housing;

a cylinder rotatably accommodated in the housing;

a piston movably supported in a cylinder chamber opened at one side of the cylinder;

a shaft member rotatably held by the housing, the shaft member penetrating the cylinder and rotating in synchronization with the cylinder; and

a valve plate disposed between the housing and the cylinder block,

the valve plate is provided with a single fluid chamber on the housing side with respect to at least one dead point of the piston and a single flow path communicating with the fluid chamber on the housing side,

the flow path is opened at a position facing a passage which is opened at the other side of the cylinder block and communicates with the cylinder chamber,

the flow path communicates via the passage with a cylinder chamber of the piston at the at least one dead point,

when the direction parallel to the rotation axis of the shaft member is an axial direction and the direction orthogonal to the axial direction is a radial direction, the center of the fluid chamber is located on the inner side in the radial direction than the center of the flow path when viewed from the axial direction,

the valve plate is formed with a fluid port penetrating the valve plate and extending along an arc centered on the rotation axis of the cylinder,

a groove is formed in the cylinder-side surface of the valve plate, and the groove is connected to one and/or the other of the two ends of the fluid port extending along the circular arc.

2. The fluid pressure rotary device according to claim 1, wherein,

the fluid pressure rotating device includes an auxiliary piston disposed in the fluid chamber.

3. The fluid pressure rotary device according to claim 1, wherein,

the fluid chamber is formed in the valve plate.

4. In a construction machine, wherein,

the construction machine includes the fluid pressure rotating device according to claim 1.