阅读说明：本技术 斜板、斜板式泵以及施工机械 (Swash plate, swash plate pump, and construction machine ) 是由 赤见俊也 于 2020-03-26 设计创作，主要内容包括：本发明提供一种斜板、斜板式泵以及施工机械。斜板式泵(10)具有：轴构件(18)；缸体(20),其被保持在轴构件；活塞(25),其以能够移动的方式配置于缸体的缸室(21)；滑靴(26),其与活塞的端部连接起来；斜板(50),其具有形成供轴构件穿过的中央孔(51)的内壁面部(IS)以及与随着轴构件的旋转而旋转的滑靴接触的接触面部(CS)；以及壳体(15),其以轴构件能够旋转的方式支承轴构件,并收容斜板。斜板(50)设置有一端在内壁面部开口且另一端在接触面开口的孔(60)。孔(60)经由设置于活塞的通路(25P)与缸室连通。(The invention provides a swash plate, a swash plate pump, and a construction machine. A swash plate pump (10) is provided with: a shaft member (18); a cylinder (20) held by the shaft member; a piston (25) which is movably disposed in a cylinder chamber (21) of a cylinder; a slipper (26) connected with the end of the piston; a swash plate (50) having an inner wall surface section (IS) in which a central hole (51) through which the shaft member passes IS formed, and a contact surface section (CS) that contacts a shoe that rotates with rotation of the shaft member; and a housing (15) that rotatably supports the shaft member and accommodates the swash plate. The swash plate (50) is provided with a hole (60) having one end opening at the inner wall surface portion and the other end opening at the contact surface. The hole (60) communicates with the cylinder chamber via a passage (25P) provided in the piston.)

1. A swash plate type pump in which, in a swash plate type pump,

the swash plate pump includes:

a shaft member;

a cylinder held on the shaft member;

a piston disposed movably in a cylinder chamber of the cylinder block;

a slipper connected with the piston;

a swash plate having: an inner wall surface portion that forms a central hole through which the shaft member passes; and a contact surface portion that is in contact with a shoe that rotates with rotation of the shaft member, the swash plate being provided with a hole, one end of the hole being open to the inner wall surface portion, the other end of the hole being open to the contact surface portion, and the hole communicating with a cylinder chamber via a passage provided in the piston; and

and a housing that supports the shaft member so that the shaft member can rotate, and that houses the swash plate.

2. The swash plate pump according to claim 1,

the shoe has an outer contour covering the entire opening on the other end side of the hole of the swash plate.

3. The swash plate pump according to claim 1,

an exhaust port is provided in the housing in communication with the bore of the swash plate.

4. The swash plate pump according to claim 1,

the housing has a swash plate support portion supporting the swash plate,

the hole opens at a position of the contact surface portion facing the cylinder chamber on the low pressure side,

the swash plate is provided with a flow path, one end of which opens at a position facing the high-pressure side cylinder chamber of the contact surface portion, and the other end of which opens at a chamber between a portion of the swash plate facing the low-pressure side cylinder chamber and the swash plate support portion.

5. The swash plate pump according to claim 1,

the holes are open only at both ends.

6. A construction machine in which, in a construction machine,

the construction machine is provided with the swash plate pump according to any one of claims 1 to 5.

7. A swash plate for a swash plate pump, wherein,

the swash plate includes:

an inner wall surface portion forming a central hole through which the shaft member passes; and

and an annular contact surface portion which is located around the center hole and which is in contact with the shoe holding the piston, wherein the contact surface portion is provided with an opening whose one end is open to the inner wall surface portion.

Technical Field

The invention relates to a swash plate, a swash plate pump, and a construction machine.

Background

As disclosed in patent document 1 (jp JPH2-26772A), for example, a swash plate pump is used in various technical fields. The swash plate pump fills the casing with the working oil before being actually used. At this time, the air inside the case is discharged through the air outlet provided in the case. This air discharge operation is performed every time the working oil is replaced for maintenance or the like. Therefore, it is desirable to reduce the workload of air discharge for the swash plate pump.

Disclosure of Invention

The present invention has been made in view of the above points, and an object thereof is to reduce the burden of air discharge on a swash plate pump.

The swash plate pump of the present invention includes:

a shaft member;

a cylinder held on the shaft member;

a piston disposed movably in a cylinder chamber of the cylinder block;

a slipper connected with the piston;

a swash plate having: an inner wall surface portion that forms a central hole through which the shaft member passes; and a contact surface portion that is in contact with a shoe that rotates with rotation of the shaft member, the swash plate being provided with a hole, one end of the hole being open to the inner wall surface portion, the other end of the hole being open to the contact surface portion, and the hole communicating with a cylinder chamber via a passage provided in the piston; and

and a housing that supports the shaft member so that the shaft member can rotate, and that houses the swash plate.

In the swash plate pump according to the present invention, the shoe may have an outer contour that covers the entire opening on the other end side of the hole of the swash plate.

In the swash plate pump according to the present invention, a discharge port that communicates with the hole of the swash plate may be provided in the housing.

In the swash plate pump of the present invention, it is also possible,

the housing has a swash plate support portion supporting the swash plate,

the hole opens at a position of the contact surface portion facing the cylinder chamber on the low pressure side,

the swash plate is provided with a flow path, one end of which opens at a position facing the high-pressure side cylinder chamber of the contact surface portion, and the other end of which opens at a chamber between a portion of the swash plate facing the low-pressure side cylinder chamber and the swash plate support portion.

In the swash plate pump of the present invention, it is also possible,

the flow path includes:

a high-pressure side passage extending linearly between a position of the contact surface portion facing the high-pressure side cylinder chamber and a high-pressure side chamber provided between a portion of the swash plate facing the high-pressure side cylinder chamber and the swash plate support portion;

a linear low-pressure side passage communicating with a low-pressure side chamber provided between a portion of the swash plate facing the low-pressure side cylinder chamber and the swash plate support portion;

a straight 1 st relay flow path connected to the high-pressure side flow path; and

and a straight 2 nd relay flow path connected to the low-pressure side flow path and the 1 st relay flow path.

With the swash plate pump of the present invention, the hole may be opened only at both ends.

The construction machine of the present invention includes any one of the swash plate pumps of the present invention described above.

The swash plate of the present invention includes:

an inner wall surface portion forming a central hole through which the shaft member passes; and

and an annular contact surface portion which is located around the center hole and contacts the shoe holding the piston, and which is provided with an opening having one end side opened to the other end side of the hole of the inner wall surface portion.

According to the present invention, the burden of air discharge of the swash plate pump can be greatly reduced.

Drawings

Fig. 1 is a diagram for explaining an embodiment of the present invention, and is a side view showing an example of a construction machine to which a swash plate pump can be applied.

Fig. 2 is a longitudinal sectional view showing an example of a swash plate type pump applicable to the construction machine of fig. 1.

Fig. 3 is a perspective view showing a swash plate of the swash plate pump of fig. 2.

Fig. 4 is a perspective view showing a swash plate support portion of the swash plate pump of fig. 2.

Fig. 5 is a plan view showing a contact surface portion of the swash plate of fig. 3.

Fig. 6 is a view corresponding to fig. 5, and is a plan view showing a modification of the swash plate pump.

Detailed Description

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. For ease of understanding, elements shown in the drawings may include elements whose dimensions, scales, and the like are different from actual dimensions, scales, and the like.

The swash plate pump 10 described below is a so-called variable displacement swash plate type piston pump. The swash plate pump 10 pumps working oil into a cylinder chamber 21 to be discussed later and discharges the working oil from the cylinder chamber 21. More specifically, the shaft member 18 is rotated by power from a power source such as an engine, the cylinder block 20 coupled to the shaft member 18 by spline coupling or the like is rotated, and the piston 25 is reciprocated by the rotation of the cylinder block 20. By the reciprocating operation of the piston 25, the working oil is sucked into a partial cylinder chamber 21 and the working oil is discharged from the other cylinder chamber 21.

Typically, the swash plate pump 10 of the present embodiment can be used as a hydraulic circuit or a drive device provided in a construction machine, but may be applied to other applications, and the application is not particularly limited. Fig. 1 shows a hydraulic excavator 90 as an example of a construction machine CM to which the swash plate pump 10 of the present embodiment can be applied.

In general, the hydraulic excavator 90 includes: a lower frame 91 having a crawler belt; an upper frame 92 provided to be rotatable with respect to the lower frame 91; a boom 93 attached to the upper frame 92; an arm 94 attached to the boom 93; and a bucket 95 attached to the arm 94. The hydraulic cylinders 96A, 96B, and 96C are actuators for a boom, an arm, and a bucket, respectively, and drive the boom 93, the arm 94, and the bucket 95, respectively. When the upper frame 92 is rotated, the rotational driving force from the rotating device 97 is transmitted to the upper frame 92. When the hydraulic excavator 90 is to be driven, the rotational driving force from the driving device 98 is transmitted to the crawler belts of the lower frame 91. The turning device 97 and the traveling device 98 are constituted by hydraulic motors that output rotation by inputting hydraulic pressure. The swash plate pump 10 supplies pressure oil to hydraulic actuators such as the hydraulic cylinders 96A, 96B, and 96C, the slewing device 97, and the traveling device 98.

Next, the swash plate pump 10 will be described.

The swash plate pump 10 includes a housing 15, a shaft member 18, a cylinder block 20, pistons 25, a valve plate 30, a tilt adjustment mechanism 35, and a swash plate 50 as main components. Hereinafter, each constituent element will be described.

As shown in fig. 2, the housing 15 has a 1 st housing component 15a and a 2 nd housing component 15b fixed to the 1 st housing component 15 a. The 1 st housing component 15a and the 2 nd housing component 15b are fixed to each other using a fastener such as a bolt. The housing 15 has a housing space S formed therein. The cylinder block 20, the piston 25, the valve plate 30, the yaw adjusting mechanism 35, and the swash plate 50 are disposed in the housing space S.

In the illustrated example, the valve plate 30 is disposed inside the 1 st housing assembly 15 a. The 1 st housing assembly 15a is formed with a 1 st oil passage 11 and a 2 nd oil passage 12 that communicate with the cylinder chamber 21 of the cylinder block 20 via the valve plate 30. In the drawings, the 1 st oil passage 11 and the 2 nd oil passage 12 are represented by lines for convenience of explanation, but actually have appropriate inner dimensions (inner diameters) corresponding to supply and discharge of the hydraulic oil to and from the cylinder chamber 21 of the cylinder block 20. The 1 st oil passage 11 and the 2 nd oil passage 12 are provided so as to penetrate the casing 15 from inside the casing 15 to outside the casing 15. The 1 st oil passage 11 and the 2 nd oil passage 12 each communicate with an actuator, a hydraulic pressure source, and the like provided outside the swash plate pump 10.

The shaft member 18 is rotatably supported by the housing 15 via bearings 19a and 19 b. The shaft member 18 is rotatable about its central axis line as a rotation axis RA. One end of the shaft member 18 is rotatably supported by the 1 st housing component 15a via a bearing 19 b. The other end of the shaft member 18 is rotatably supported by the 2 nd housing assembly 15b via a bearing 19a, and the other end of the shaft member 18 extends out of the housing 15 through a through hole provided in the 2 nd housing assembly 15 b. A seal member is provided between the housing 15 and the shaft member 18 at a portion where the shaft member 18 penetrates the housing 15, and prevents the working oil from flowing out of the housing 15. A portion of the shaft member 18 extending from the housing 15 is connected to an input member such as a motor, an engine, or the like.

The cylinder 20 has a cylindrical or cylindrical shape disposed around the rotation axis RA. The cylinder block 20 is penetrated by the shaft member 18. The cylinder block 20 is coupled to the shaft member 18 by, for example, spline coupling. The cylinder block 20 is rotatable about the rotation axis RA in synchronization with the shaft member 18.

Further, in the case of spline coupling between the shaft member 18 and the cylinder block 20, the shaft member 18 has spline teeth on its surface extending in an axial direction DA parallel to the rotation axis RA. Further, a part of the spline teeth may be exposed to the housing space S in the housing 15 without being covered by the cylinder block 20. The spline teeth exposed inside the housing 15 can promote the discharge of air (air bubbles) remaining inside the housing 15 as discussed later. It is particularly preferred that the spline teeth exposed in the housing 15 extend into the central bore 51 of the swash plate 50 discussed later.

The cylinder block 20 has a plurality of cylinder chambers 21 formed therein. The plurality of cylinder chambers 21 are arranged at equal intervals in the circumferential direction around the rotation axis RA. Each cylinder chamber 21 opens on the swash plate 50 side in the axial direction DA parallel to the rotation axis RA. In the illustrated example, each cylinder chamber 21 extends parallel to the axial direction DA. Further, a connection port 22 is formed corresponding to each cylinder chamber 21. The connection port 22 opens the cylinder chamber 21 on the side closer to the valve plate 30 in the axial direction DA.

A piston 25 is provided corresponding to each cylinder chamber 21. A part of each piston 25 is disposed in the cylinder chamber 21. Each piston 25 extends in the axial direction DA from the corresponding cylinder chamber 21 toward the swash plate 50. The piston 25 is movable in the axial direction DA relative to the cylinder 20. That is, the piston 25 can advance toward the swash plate 50 side in the axial direction DA to increase the volume of the cylinder chamber 21. The piston 25 can retract toward the valve plate 30 in the axial direction DA to reduce the volume of the cylinder chamber 21.

The swash plate 50 is supported in the housing 15. The swash plate 50 is disposed to face the cylinder block 20 and the piston 25 in the axial direction DA. As shown in fig. 2, the shaft member 18 penetrates through a central hole 51 of the swash plate 50. The swash plate 50 has: an inner wall surface portion IS that forms (IS divided ) a central hole 51 through which the shaft member 18 passes; and a contact surface portion CS that contacts the shoe 26 that rotates with rotation of the shaft member 18. The contact surface section CS is located at a position facing the cylinder 20 and the piston 25. The swash plate 50 is supported in the housing 15 such that the contact surface portion CS can be inclined with respect to a surface perpendicular to the rotation axis RA. The structure for holding the swash plate 50 is discussed later.

As shown in fig. 2, the shoe 26 is provided on the contact surface portion CS of the swash plate 50. The shoe 26 holds the head (end) of the piston 25. Specifically, a head portion serving as one end of the piston 25 is formed in a spherical shape. The shoe 26 has a hole that can receive approximately half of the spherical head. The shoe 26 holding the head of the piston 25 can move on the contact surface portion CS of the swash plate 50 while contacting the contact surface portion CS.

The swash plate pump 10 further includes a holding plate 27 disposed in the housing 15. The holding plate 27 is an annular and plate-shaped member. The holding plate 27 is inserted through the shaft member 18 and supported by the shaft member 18. The support portion 18a of the shaft member 18 that supports the retaining plate 27 is formed in a curved surface shape. Therefore, the holding plate 27 can change its orientation in a state of being supported by the shaft member 18. As shown in fig. 2, the plate-like holding plate 27 is inclined along the contact surface portion CS of the swash plate 50 and contacts the shoe 26.

Further, a piston pressing member 28 including a spring and the like is provided between the shaft member 18 and the holding plate 27. The retainer plate 27 is pressed against the swash plate 50 side in the axial direction DA by the piston pressing member 28. As a result, the holding plate 27 can press the shoe 26 and the piston 25 toward the contact surface portion CS of the swash plate 50. In the illustrated example, the piston pressing member 28 includes: a spring member 28a supported by the cylinder 20; and a pin 28b located between the spring member 28a and the support member 18 a. The spring member 28a presses the support member 18a against the holding plate 27 via the pin 28b, and as a result, presses the shoe 26 toward the swash plate 50.

The valve plate 30 is fixed to the 1 st housing assembly 15 a. That is, the valve plate 30 is stationary while the cylinder block 20 rotates together with the shaft member 18. The valve plate 30 has two or more ports, not shown. Each port communicates with the 1 st oil passage 11 or the 2 nd oil passage 12. The ports are formed, for example, along an arc centered on the rotation axis RA, and face the connection ports 22 corresponding to the respective cylinder chambers 21 in sequence as the cylinder block 20 rotates. As a result, the connection between the cylinder chambers 21 and the 1 st oil passage 11 and the 2 nd oil passage 12 is switched according to the rotation state of the cylinder block 20.

Here, the operation of the swash plate pump 10 will be described. The shaft member 18 rotates about the rotation axis line RA by a rotational driving force from an input member such as a motor or an engine, not shown. At this time, the piston 25 advances so as to protrude from the cylinder 20 and retreats into the cylinder 20 as the cylinder 20 rotates. The volume of the cylinder chamber 21 changes due to the forward and backward movements of the piston 25.

During a period in which the piston 25 retreats from a position (top dead center) at which it extends out to the maximum extent from the cylinder chamber 21 to a position (bottom dead center) at which it enters into the cylinder chamber 21 to the maximum extent, the capacity of the cylinder chamber 21 in which the piston 25 is housed decreases. During at least a part of this period, the cylinder chamber 21 housing the piston 25 that is moving backward is connected to, for example, the 1 st oil passage 11 via a port, not shown, of the valve plate 30, and the working oil is discharged from the cylinder chamber 21. The 1 st oil passage 11 is connected to an external actuator or the like as a high-pressure side flow passage.

On the other hand, the capacity of the cylinder chamber 21 in which the piston 25 is accommodated increases while the piston 25 advances from the bottom dead center to the top dead center. During at least a part of this period, the cylinder chamber 21 housing the advancing piston 25 is connected to, for example, the 2 nd oil passage 12 via a port, not shown, of the valve plate 30, and the working oil is sucked into the cylinder chamber 21. The 2 nd oil passage 12 is connected as a low-pressure side flow passage to a tank or the like for storing hydraulic oil.

In the swash plate pump 10 described above, the contact surface CS of the swash plate 50 regulates the amount of protrusion of the piston 25 from the cylinder block 20. Therefore, the stroke of the reciprocating motion of the piston 25 in the axial direction DA is determined depending on the inclination of the swash plate 50, and more precisely, the magnitude of the inclination angle θ i (see fig. 2) of the contact surface portion CS of the swash plate 50 with respect to the plane perpendicular to the axial direction DA. Further, by changing the inclination of the swash plate 50, that is, by deflecting the swash plate 50, the output of the swash plate pump 10 can be changed. Specifically, when the inclination of the swash plate 50 is increased, in other words, when the inclination angle θ i is increased, the output of the swash plate pump 10 is increased. When the inclination of the swash plate 50 is small, in other words, when the inclination angle θ i is small, the output of the swash plate pump 10 decreases. If the contact surface portion CS of the swash plate 50 is perpendicular to the axial direction DA, that is, if the inclination angle θ i is 0 °, theoretically, no output can be obtained from the swash plate pump 10.

Therefore, in the illustrated swash plate pump 10, the swash plate 50 is held so as to be able to deflect, that is, so as to be able to change the inclination angle θ i between the contact surface portion CS and the axial direction DA. Hereinafter, a structure for holding the swash plate 50 in the housing 15 so as to be able to deflect will be described.

As shown in fig. 2, the swash plate pump 10 includes a support member 70 that supports the swash plate 50 so as to be able to change the inclination of the swash plate 50, that is, a support member 70 that supports the swash plate 50 so as to be able to deflect. As shown in fig. 4, the support member 70 has a base portion 72 fixed to the housing 15 and a swash plate support portion 73 provided on the base portion 72. The base portion 72 is formed with a central through hole 71 through which the shaft member 18 passes. The base portion 72 is provided with a 1 st swash plate support portion 73A and a 2 nd swash plate support portion 73B so as to sandwich the center through hole 71. The shaft member 18 passes through the central through hole 71 between the two swash plate support portions 73A and 73B. Each swash plate support portion 73 is formed with a housing recess 74 that houses the bulging portion 54 of the swash plate 50, which will be discussed later. The accommodation recess 74 has a shape corresponding to a part of a side surface of the cylinder (for example, a side surface of a semi-cylinder). In the illustrated example, the support member 70 is formed separately from the housing 15, and is fixed to the housing 15 by a fastener or the like. However, the present invention is not limited to this example, and the support member 70 may be a part of the housing 15, for example, a part of the 2 nd housing assembly 15b may be formed integrally with the 2 nd housing assembly 15 b.

On the other hand, as shown in fig. 2, the swash plate 50 has a supported portion 53 disposed on the swash plate supporting portion 73 of the supporting member 70. The supported portion 53 includes a bulging portion 54 having a shape complementary to the accommodation recess 74. The bulge portion 54 has a shape corresponding to a part of a cylinder (for example, a semi-cylinder). The swash plate 50 includes a 1 st supported portion 53A and a 2 nd supported portion 53B which are arranged to be separated in the depth direction of the paper surface of fig. 2. The shaft member 18 passes through the central hole 51 between the two supported portions 53A and 53B. The 1 st supported portion 53A is supported by the 1 st swash plate supporting portion 73A, and the 2 nd supported portion 53B is supported by the 2 nd swash plate supporting portion 73B.

In this example, the swash plate support portion 73 of the support member 70 has a support surface 75 formed along an arc in the accommodation recess 74. On the other hand, the supported portion 53 of the swash plate 50 has a supported surface 55 formed along an arc. When the supported portion 53 is disposed in the accommodation recess 74 of the swash plate support portion 73, the supported surface 55 of the supported portion 53 can be in contact with the support surface 75 of the swash plate support portion 73, particularly in surface contact with a curved surface. The supported portion 53 slides, i.e., moves in contact with (or in a sliding manner) the swash plate support portion 73 in the accommodation recess 74, so that the swash plate 50 including the supported portion 53 rotates relative to the support member 70 about the center line of the arc defined by the supported surface 55 and the support surface 75. Although not particularly limited, the axis of the yawing operation may be located on the contact surface portion CS of the swash plate 50. With this configuration, the swash plate 50 is supported by the support member 70 so that the inclination of the contact surface portion CS can be changed.

As shown in fig. 2, the swash plate pump 10 further includes a swash plate 50 having a contact surface CS and a tilt adjustment mechanism 35 for controlling the tilt of the contact surface CS. In the illustrated example, the yaw adjusting mechanism 35 includes a swash plate pressing member 36 and a swash plate control device 37. The yaw adjustment mechanism 35 will be explained below.

The swash plate 50 shown in fig. 3 includes: a central portion 50a, a 1 st force receiving portion 50b, and a 2 nd force receiving portion 50 c. The central portion 50a is disposed between the 1 st force receiving portion 50b and the 2 nd force receiving portion 50 c. The center portion 50a is provided with the center hole 51, the contact surface portion CS, and the bulge portion 54. The 1 st force receiving portion 50b and the 2 nd force receiving portion 50c are portions extending from the central portion 50a to opposite sides, respectively.

The swash plate 50 is pressed by the swash plate pressing member 36 and the swash plate controller 37 of the swash plate adjusting mechanism 35 so as to deflect the swash plate 50 in opposite directions to each other. The swash plate 50 is held at a certain swash position by balancing the force pressed by the swash plate pressing member 36 and the force pressed by the swash plate control device 37. In the illustrated example, the swash plate pressing member 36 contacts the 1 st force receiving portion 50b of the swash plate 50 to press the swash plate 50 such that the swash plate 50 is deflected counterclockwise in fig. 2. The swash plate control device 37 contacts the 2 nd force receiving portion 50c of the swash plate 50 to press the swash plate 50 so as to deflect the swash plate 50 clockwise in fig. 2.

The swash plate pressing member 36 is supported by the 1 st case unit 15a of the case 15. The swash plate pressing member 36 is formed of, for example, a compression spring. Thus, the swash plate pressing member 36 presses the swash plate 50 with a restoring force corresponding to the deformation force.

On the other hand, the swash plate control device 37 is configured to adjust an actuator 38 and has a control piston 39. The control piston 39 can approach (advance) the swash plate 50 and retreat (retreat) away from the swash plate 50 in the axial direction DA. The control piston 39 presses the 2 nd force receiving portion 50c of the swash plate 50. The control piston 39 is driven, for example, hydraulically. Further, the force with which the control piston 39 presses the 2 nd force receiving portion 50c can be adjusted. That is, the inclination angle θ i of the swash plate 50 can be controlled by adjusting the force output from the swash plate control device 37. Here, the inclination angle θ i is an inclination angle of the swash plate 50 with respect to a plane perpendicular to the axial direction DA in the operating direction of the pistons 25, that is, an angle formed by a contact surface portion CS of the swash plate 50 with respect to a perpendicular plane to the axial direction DA (see fig. 2).

In the illustrated example, when there is no output from the swash plate control device 37, the inclination angle θ i is the maximum, and the swash plate 50 shown in fig. 2 is in the maximum inclination state. The control piston 39 of the swash plate control device 37 presses the 2 nd force receiving portion 50c of the swash plate 50, and the swash plate 50 is raised from the maximum inclination state to be able to reduce the inclination angle θ i. The swash plate 50 is pressed with a greater force by the swash plate control device 37, and the swash plate 50 is raised so that the inclination angle θ i becomes 0 ° or a minimum angle close to 0 °.

In the illustrated typical example, the swash plate 50 can be tilted from the maximum inclination state shown in fig. 2 to the standing state, and is not intended to be tilted to the opposite side of the state shown in fig. 2 beyond the standing state. Therefore, in the illustrated typical example, the standing state with the inclination angle of 0 ° becomes the minimum inclination state. In such an example, the pressure in the cylinder chamber 21 becomes high when passing through a region of the contact surface portion CS of the swash plate 50 where one supported portion 53 (the 1 st supported portion 53A in the illustrated example) overlaps with the other supported portion 53 (the 2 nd supported portion 53B in the illustrated example) in the axial direction DA, and the pressure in the cylinder chamber 21 becomes low when passing through a region of the contact surface portion CS of the swash plate 50 where the other supported portion 53 (the 2 nd supported portion 53B in the illustrated example) overlaps with the axial direction DA. In other words, one supported portion 53 (in the illustrated example, the 1 st supported portion 53A) faces the high-pressure side cylinder chamber 21 in the axial direction DA, and the other supported portion 53 (in the illustrated example, the 2 nd supported portion 53B) faces the low-pressure side cylinder chamber 21 in the axial direction DA. The piston 25 in the high-pressure side cylinder chamber 21 moves from the top dead center toward the bottom dead center, and the piston 25 in the low-pressure side cylinder chamber 21 moves from the bottom dead center toward the top dead center.

Here, during the operation of the swash plate pump 10, the swash plate 50 is pressed toward the support member 70 by the pressure of the hydraulic oil in the cylinder chamber 21 in which the piston 25 is accommodated. In the illustrated example, the 1 st supported portion 53A on the high pressure side is pressed against the 1 st swash plate supporting portion 73A with a stronger force, and the 2 nd supported portion 53B on the low pressure side is pressed against the 2 nd swash plate supporting portion 73B with a weaker force. Further, when the swash plate 50 is pressed against the support member 70 at a high pressure, a force required for the swash plate 50 to deflect increases, and the swash plate 50 cannot be deflected smoothly.

On the other hand, as can be understood from fig. 3 and 4, a chamber CA is formed between the swash plate 50 and the support member 70. The chamber CA communicates with a flow path P formed in the swash plate 50. Here, the flow path P is a flow path of pressurized hydraulic oil. Thus, the chamber CA is filled with pressure oil, i.e., pressurized working oil. The swash plate 50 is pressed by the pressure oil in the chamber CA in a direction away from the swash plate support portion 73 in the axial direction DA, in other words, in a direction toward the cylinder block 20 and the piston 25 in the axial direction DA. Further, an oil film is formed between the supported surface 55 and the supporting surface 75, and direct frictional contact between the swash plate supporting portion 73 and the supported portion 53 can be avoided. By supplying the pressure oil into the chamber CA in this manner, friction between the swash plate 50 and the swash plate support portion 73 can be reduced. This can smooth the swash plate 50 deflection by the deflection adjusting mechanism 35.

In the illustrated example, the flow path P communicates with the high-pressure side cylinder chamber 21. Therefore, the working oil in the cylinder chamber 21 on the high pressure side is supplied to the chamber CA. As shown in fig. 3, one end of the flow path P opens at a position facing the high-pressure side cylinder chamber of the contact surface portion CS. The other end of the flow path P communicates with a chamber CA provided between the 1 st supported portion 53A and the 1 st swash plate supporting portion 73A of the swash plate 50 facing the high-pressure side cylinder chamber 21. The flow path P is a linear path and can be formed by machining such as drilling. Further, a piston through hole 25P is formed in each piston. The shoe 26 holds the periphery of the head portion of the piston 25 so that the piston through hole 25P is exposed to the contact surface portion CS. The shoe 26 moves on the contact surface portion CS, and the piston through hole 25P faces the opening of the flow path P on the contact surface portion CS and communicates with the flow path P. At this time, the through hole of the annular portion of the shoe 26 holding the head portion of the piston 25 also functions as a part of the pressure oil passage. In the illustrated example, the chamber CA is configured as a recess formed in the support surface 75 of the 1 st swash plate support portion 73A (see fig. 4), but the chamber CA may be configured as a recess formed in the supported surface 55 of the 1 st supported portion 53A, regardless of the example.

In the swash plate pump 10 having the above-described configuration, the housing space S in the housing 15 is filled with the working oil. When the swash plate pump 10 is used while air remains in the housing space S, there is a possibility that abnormal noise may be generated, operation failure may occur, and the pump may be damaged. Therefore, the air is removed from the casing 15 before the swash plate pump 10 is used after manufacture, before the swash plate pump 10 is used after disassembly and maintenance, or before the swash plate pump 10 is used after replacement of the working oil. Conventionally, this air discharge is performed through a discharge port 13 (see fig. 2) formed in the casing 15.

On the other hand, in the present embodiment, a work load for discharging air from the housing 15 is considered to be reduced. Specifically, as shown in fig. 3, the swash plate 50 is provided with a hole 60. One end of the hole 60 opens at the inner wall surface portion IS, and the other end of the hole 60 opens at the contact surface portion CS. That IS, the hole 60 has the 1 st opening 61 on the inner wall surface portion IS and the 2 nd opening 62 on the contact surface portion CS. The 2 nd opening 62 communicates with the piston through hole 25P of the piston 25 that moves together with the shoe 26 on the contact surface portion CS. Therefore, the hole 60 can communicate with the cylinder chamber 21 of the cylinder block 20 via a passage provided in the shoe 26 and the piston 25.

In particular, in the illustrated example, the 2 nd opening 62 is located in a region of the contact surface portion CS facing the low-pressure side cylinder chamber 21. The piston 25 held in the cylinder chamber 21 on the low pressure side moves from the bottom dead center at which the piston enters the cylinder chamber 21 to the maximum toward the top dead center at which the piston protrudes from the cylinder chamber 21 to the maximum. Therefore, the 2 nd opening 62 communicates with the cylinder chamber 21 accommodating the piston 25 from the bottom dead center toward the top dead center at the contact surface portion CS. The cylinder chamber 21 on the low-pressure side becomes negative pressure, and the working oil is normally sucked through the valve plate 30. Therefore, the hole 60 of the swash plate 50 communicates with the cylinder chamber 21 on the low pressure side via the 2 nd opening 62, and air remaining in the housing 15 can be sucked and discharged from the 1 st opening 61.

In the housing 15, when the shaft member 18 rotates, the hydraulic oil having a higher specific gravity than that of air moves outward in the radial direction due to the centrifugal force. Conversely, when the shaft member 18 rotates, air having a smaller specific gravity than the working oil moves radially inward. Here, the radial direction refers to a direction orthogonal to the central axis RA. Further, the radially outer side refers to a side radially distant from the central axis RA, and the radially inner side refers to a side radially close to the central axis RA. Therefore, when the swash plate pump 10 starts to operate and the shaft member 18 rotates, air in the housing 15 is likely to collect around the shaft member 18.

The 1 st opening 61 of the hole 60 is opened in the central hole 51 of the swash plate 50. The 1 st opening 61 is adjacent to the shaft member 18 and faces the shaft member 18. Therefore, by rotating the shaft member 18, air is automatically collected around the shaft member 18, and the air around the shaft member 18 can be sucked into the cylinder chamber 21 on the low pressure side through the hole 60, the through hole of the slipper 26, and the piston through hole 25P of the piston 25. The air drawn from the housing space S into the cylinder chamber 21 is discharged to the outside of the housing 15 through, for example, the 2 nd oil passage 12. That is, the air discharge can be automatically performed by starting the operation of the swash plate pump 10. Therefore, the work load of air discharge can be substantially eliminated. Such effects can be said to be significant effects that cannot be predicted by those skilled in the art based on technical standards.

In particular, in the illustrated example, the holes 60 are open only at both ends. Therefore, air can be efficiently sucked into the bore 60 from the 1 st opening 61 of the bore 60 by the suction force from the low-pressure side cylinder chamber 21. That IS, suction can be performed with a strong suction force from the 1 st opening 61 that constitutes one end side of the hole 60 that opens in the inner wall surface portion IS. This enables efficient air discharge.

The shoe 26 has an outer contour covering the entire 2 nd opening 62 which is the other end side of the hole 60 of the swash plate 50. More specifically, the annular portion of the shoe 26 that holds the head portion of the piston 25 and that is in contact with the contact surface portion CS has an outer contour that can cover the entire 2 nd opening 62. For example, the width of the shoe 26 in the radial direction is larger than the width of the 2 nd opening 62 in the radial direction. According to such an example, suction can be performed with a strong suction force from the 1 st opening 61 of the hole 60 that opens in the inner wall surface portion IS. This enables efficient air discharge.

Further, in the case where the shaft member 18 is spline-coupled with the cylinder block 20, the shaft member 18 has spline teeth extending in an axial direction DA parallel to the rotation axis RA on its surface. Further, since the part of the spline teeth is exposed to the housing space S in the housing 15 without being covered by the cylinder block 20, the centrifugal force can be efficiently applied to the hydraulic oil in the housing space S. This can facilitate the movement of the hydraulic oil in the housing space S to the radially outer side. At the same time, the movement of the air in the housing space S to the radially inner side can be promoted, and the air can be efficiently discharged. When the spline teeth exposed in the housing 15 extend into the central hole 51 of the swash plate 50, air is guided into the central hole 51 by the spline teeth. This also enables air to be sucked more efficiently from the 1 st opening 61 that opens in the center hole 51.

However, the movement of the air radially inward is not limited to the movement by the exposed spline teeth, and may be performed by a convex portion or the like provided on the rotating shaft member 18. The movement of the air into the center hole 51 along the axial direction DA is not limited to the movement by the exposed spline teeth, and may be performed by a linear protrusion extending in the axial direction DA provided on the rotating shaft member 18.

When the change per unit time in the volume of the cylinder chamber 21 becomes large, the suction force from the cylinder chamber 21 on the low pressure side becomes large. Therefore, when the cylinder chamber 21 passes through an intermediate position PM between a bottom dead center position PY at which the piston 25 positioned at the bottom dead center and retreating to the maximum extent into the cylinder chamber 21 is accommodated and a top dead center position PX at which the piston 25 positioned at the top dead center and projecting from the cylinder chamber 21 to the maximum extent, in the circumferential direction DC centered on the rotation axis RA of the shaft member 18, the suction force becomes maximum in the plan view of the contact surface portion CS shown in fig. 5. Further, the 2 nd opening 62 of the hole 60 is preferably located in a position within an angular range of less than 30 ° from the rotation axis RA in the circumferential direction at the intermediate position PM ± and is an advantageous condition from the viewpoint of efficiently performing air discharge.

According to the embodiment described above, the swash plate pump 10 includes: a shaft member 18; a cylinder 20 held by the shaft member 18; a piston 25 disposed movably in the cylinder chamber 21 of the cylinder block 20; a slipper 26 connected to an end of the piston 25; a swash plate 50 having an inner wall surface portion IS forming a central hole 51 through which the shaft member 18 passes and a contact surface portion CS contacting a shoe rotating with rotation of the shaft member 18; and a housing 15 that supports the shaft member 18 such that the shaft member 18 can rotate, and that houses the swash plate 50. When the shaft member 18 rotates in the housing 15, the hydraulic oil moves radially outward due to centrifugal force, and air having a lower specific gravity than the hydraulic oil moves radially inward. On the other hand, the swash plate 50 IS provided with a hole 60 that opens in the inner wall surface portion IS and the contact surface portion CS. The bore 60 communicates with the low-pressure side cylinder chamber 21 via a passage (through-hole) formed in the shoe 26 and a passage (piston through-hole 25P) formed in the piston 25. Thus, the air that has moved to the radially inner side IS sucked from the 1 st opening 61 of the inner wall surface portion IS, and the air can be sucked from the inside of the housing 15. That is, when the pump is operated, the air in the casing 15 is automatically discharged.

While one embodiment has been described with reference to a plurality of specific examples, these specific examples are not intended to limit the embodiment. The above-described embodiment can be implemented in various other specific examples, and various omissions, substitutions, changes, additions, and the like can be made without departing from the scope of the invention.

An example of the modification will be described below with reference to the drawings. In the following description and the drawings used in the following description, the same reference numerals as those used for corresponding portions of the above-described specific example are used for portions that can be configured in the same manner as the above-described specific example, and overlapping description is omitted.

First, in the above-described embodiment, an example is shown in which the flow path P provided in the swash plate 50 extends linearly between the position of the contact surface portion CS facing the high-pressure side cylinder chamber 21 and the high-pressure side chamber CA provided between the swash plate 50 facing the high-pressure side cylinder chamber 21 (the 1 st supported portion 53A) and the swash plate support portion 73 (the 1 st swash plate support portion 73A). In this example, by supplying the pressure oil in the high-pressure side cylinder chamber 21 to the high-pressure side chamber CA, friction between the swash plate 50 and the swash plate support portion 73 is reduced, and smooth and stable deflection of the swash plate 50 can be achieved. However, the present invention is not limited to this example, and the flow path P having one end opening at a position facing the high-pressure side cylinder chamber 21 of the contact surface portion CS communicates not only with the high-pressure side chamber CA but also with the low-pressure chamber CB located between the swash plate support portion (2 nd swash plate support portion 73B) and a portion (2 nd supported portion 53B) of the swash plate 50 facing the low-pressure side cylinder chamber 21. According to this modification, the swash plate 50 can be more smoothly tilted on the swash plate support portion 73.

In the example shown in fig. 6, the flow path P includes a high-pressure side flow path PA, a low-pressure side flow path PB, a 1 st relay flow path PC, and a 2 nd relay flow path PD. The high-pressure side passage PA extends linearly between the high-pressure side chamber CA and a position of the contact surface portion CS facing the high-pressure side cylinder chamber 21. The high-pressure side flow path PA can be the same as the flow path P of the example shown in fig. 5. The low-pressure side flow passage PB extends linearly and communicates with the low-pressure side chamber CB. The 1 st relay flow path PC extends linearly and communicates with the high-pressure side flow path PA. In particular, in the illustrated example, the 1 st relay flow path PC intersects the high-pressure side flow path PA. The 2 nd relay flow path PD extends linearly and communicates with the low-pressure side flow path PB. In particular, in the illustrated example, the 2 nd relay flow passage PD intersects the low-pressure side flow passage PB. In addition, the 1 st relay flow path PC and the 2 nd relay flow path PD communicate with each other.

These high-pressure side flow passage PA, low-pressure side flow passage PB, 1 st relay flow passage PC, and 2 nd relay flow passage PD can be easily formed by machining such as drilling, as an example. In the illustrated example, the high-pressure side flow passage PA penetrates the swash plate 50. The low-pressure side flow path PB is formed by machining such as drilling from the supported portion 53 side, and does not reach the contact surface portion CS. The 1 st relay flow path PC is formed by machining such as drilling from the outer side surface of the 1 st supported portion 53A, and does not penetrate the swash plate 50 but stops in the middle of the swash plate 50. The 1 st relay flow path PC extends mainly in the 1 st supported portion 53A in a direction inclined with respect to the longitudinal direction of the swash plate. The 2 nd relay flow path PD is formed by machining such as drilling from the outer side surface of the 2 nd supported portion 53B, and does not penetrate the swash plate 50 but stops in the middle of the swash plate 50. The 2 nd relay flow path PD mainly extends in the 2 nd supported portion 53B in a direction inclined with respect to the longitudinal direction of the swash plate. The 1 st relay flow path PC and the 2 nd relay flow path PD are connected to each other at the end portions. The 1 st relay flow path PC and the 2 nd relay flow path PD extend obliquely with respect to the deflection axis of the swash plate 50 so as to bypass the central hole 51. Further, the ends of the 1 st relay flow path PC and the 2 nd relay flow path PD which become the processing start side are closed by plugs or the like. Thus, the flow path P is opened only in the high-pressure side chamber CA and the low-pressure side chamber CB at positions facing the high-pressure side cylinder chamber 21 of the contact surface portion CS.

The flow path P includes the four high-pressure side flow paths PA, the low-pressure side flow paths PB, the 1 st relay flow path PC, and the 2 nd relay flow path PD extending linearly, and thus the flow path P can be easily produced without interfering with the hole 60.

In the example shown in fig. 6, the high-pressure side chamber CA may be formed by a recess formed in the supported surface 55 of the 1 st supported portion 53A, a recess formed in the support surface 75 of the 1 st swash plate support portion 73A, or a combination of a recess formed in the supported surface 55 of the 1 st supported portion 53A and a recess formed in the support surface 75 of the 1 st swash plate support portion 73A. The low pressure side chamber CB may be formed by a recess formed in the supported surface 55 of the 2 nd supported portion 53B, a recess formed in the supporting surface 75 of the 2 nd swash plate supporting portion 73B, or a combination of a recess formed in the supported surface 55 of the 2 nd supported portion 53B and a recess formed in the supporting surface 75 of the 2 nd swash plate supporting portion 73B.

In the above-described specific example, the hole 60 IS open only in the inner wall surface portion IS and the contact surface portion CS, but the present invention IS not limited to this example, and the hole 60 may communicate with the discharge port 13 provided in the housing 15. According to such an example, air can be discharged not only from the low-pressure side cylinder chamber 21 but also from the discharge port 13. Thus, the air discharge can be performed more efficiently and more reliably.

In the above-described specific example, the example in which the 2 nd opening 62 of the hole 60 is provided at the position of the contact surface portion CS facing the low-pressure side cylinder chamber 21 is shown, but the present invention is not limited to this example, and the 2 nd opening 62 of the hole 60 may be provided at the position of the contact surface portion CS facing the high-pressure side cylinder chamber 21. In this example, as the shaft member 18 rotates, pressure oil (oil) is supplied from the cylinder chamber 21 into the bore 60. The supplied pressure oil is discharged to the housing space S of the housing 15 through the 1 st opening 61. The bubbles accumulated around the shaft member 18 can be stirred and moved by the ejection of the pressure oil. This enables more efficient and reliable air discharge via the discharge port 13 provided in the casing 15, for example.