JP2020159271A - Swash plate, swash plate pump and construction machine - Google Patents

Abstract

To reduce a burden of air bleeding in a swash plate pump.SOLUTION: A swash plate pump 10 has: a shaft member 18; a cylinder block 20 held by the shaft member; a piston 25 movably arranged in a cylinder chamber 21 of a cylinder block; a shoe 26 connected to an end part of the piston; a swash plate 50 having an inner wall surface part IS forming a central hole 51 through which the shaft member passes, and a contact surface part CS contacting with the shoe that rotates with rotation of the shaft member; and a case 15 rotatably supporting the shaft member and accommodating the swash plate. A hole 60 is provided with a hole 60 having one end open to the inner wall surface part and the other end open to the contact surface. The hole 60 communicates with the cylinder chamber through a passage 25P provided in the piston.SELECTED DRAWING: Figure 3

Description

The present invention relates to swash plates, swash plate pumps and construction machinery.

For example, as disclosed in Patent Document 1, swash plate pumps are used in various technical fields. Before the swash plate pump is actually used, the case is filled with hydraulic oil. At this time, the air inside the case is evacuated by using the air bleeding port provided on the case. This air bleeding work is carried out every time the hydraulic oil is changed for inspection or the like. Therefore, it is required to reduce the work load of air bleeding in the swash plate type pump.

Jikkenhei No. 2-26772

The present invention has been made in consideration of the above points, and an object of the present invention is to reduce the burden of bleeding air in a swash plate type pump.

The swash plate type pump according to the present invention
Shaft member and
The cylinder block held by the shaft member and
A piston movably arranged in the cylinder chamber of the cylinder block and
The shoe connected to the piston and
It has an inner wall surface portion that forms a central hole through which the shaft member passes, and a contact surface portion that comes into contact with a shoe that rotates with the rotation of the shaft member, one end of which opens into the inner wall surface portion and the other end of the contact. A swash plate having an opening on the surface and a hole leading to the cylinder chamber through a passage provided in the piston.
A case for rotatably supporting the shaft member and accommodating the swash plate is provided.

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 in the swash plate.

In the swash plate type pump according to the present invention, the case may be provided with a discharge port leading to the hole of the swash plate.

In the swash plate type pump according to the present invention
The case has a swash plate support portion that supports the swash plate.
The hole is opened at a position facing the cylinder chamber on the low pressure side of the contact surface portion.
One end is opened at a position facing the cylinder chamber on the high pressure side of the contact surface portion, and the other end is located between the portion of the swash plate facing the cylinder chamber on the low pressure side and the swash plate support portion. A flow path opened in the chamber may be provided in the swash plate.

In the swash plate type pump according to the present invention
The flow path is
A straight line between the position of the contact surface portion facing the cylinder chamber on the high pressure side and the high pressure side chamber provided between the portion of the swash plate facing the cylinder chamber on the high pressure side and the swash plate support portion. The high-pressure side flow path extending in a shape and
A linear low-pressure side flow path leading to a low-pressure side chamber provided between a portion of the swash plate facing the cylinder chamber on the low-pressure side and the swash plate support portion,
A linear first relay flow path connected to the high-pressure side flow path and
The low pressure side flow path and the linear second relay flow path connected to the first relay flow path may be included.

In the swash plate type pump according to the present invention, the through holes may be opened only at both ends.

The construction machine according to the present invention includes any of the above-mentioned swash plate pumps according to the present invention.

The swash plate according to the present invention
The inner wall surface that forms the central hole through which the shaft member passes,
An annular contact surface portion provided with an opening that comes into contact with a shoe that is located around the central hole and holds the piston and whose one end side is the other end side of the hole opened in the inner wall surface portion.

According to the present invention, the burden of bleeding air in the swash plate type pump can be significantly reduced.

FIG. 1 is a view 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 vertical cross-sectional view showing an example of a swash plate pump that can be applied to the construction machine of FIG. FIG. 3 is a perspective view showing a swash plate of the swash plate type pump of FIG. FIG. 4 is a perspective view showing a swash plate support portion of the swash plate type pump of FIG. FIG. 5 is a plan view showing a contact surface portion of the swash plate of FIG. FIG. 6 is a view corresponding to FIG. 5, and is a plan view showing a modified example of the swash plate type pump.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. It should be noted that the elements shown in each drawing may include elements whose size, scale, etc. are shown differently from those actually shown in order to facilitate understanding.

The swash plate type pump 10 described below is a so-called variable capacity type swash plate type piston pump. The swash plate type pump 10 sucks hydraulic oil into the cylinder chamber 21, which will be described later, and discharges hydraulic oil from the cylinder chamber 21. More specifically, by rotating the shaft member 18 by the power from a power source such as an engine, the cylinder block 20 connected to the shaft member 18 by spline coupling or the like is rotated, and by the rotation of the cylinder block 20. The piston 25 is reciprocated. In response to the reciprocating operation of the piston 25, the hydraulic oil is sucked into a part of the cylinder chambers 21 and the hydraulic oil is discharged from the other cylinder chambers 21.

The swash plate type pump 10 of the present embodiment can be typically used as a hydraulic circuit or a driving device included in a construction machine, but may be applied to other uses, and the use is not particularly limited. FIG. 1 shows a hydraulic excavator 90 as an example of a construction machine CM to which the swash plate type pump 10 according to the present embodiment can be applied.

The hydraulic excavator 90 generally includes a lower frame 91 provided with a crawler, an upper frame 92 rotatably provided with respect to the lower frame 91, a boom 93 attached to the upper frame 92, and an arm 94 attached to the boom 93. , A bucket 95 attached to the arm 94. The hydraulic cylinders 96A, 96B, 96C are actuators for a boom, an arm, and a bucket, and drive the boom 93, the arm 94, and the bucket 95, respectively. Further, when the upper frame 92 is swiveled, the rotational driving force from the swivel device 97 is transmitted to the upper frame 92. Then, when the hydraulic excavator 90 is driven, the rotational driving force from the traveling device 98 is transmitted to the crawler of the lower frame 91. The swivel device 97 and the traveling device 98 are composed of a hydraulic motor that outputs rotation by inputting hydraulic pressure. The swash plate type pump 10 is responsible for supplying pressure oil to hydraulic actuators such as hydraulic cylinders 96A, 96B, 96C, swivel device 97, and traveling device 98.

Next, the swash plate type pump 10 will be described.

The swash plate type pump 10 has a case 15, a shaft member 18, a cylinder block 20, a piston 25, a valve plate 30, a tilt adjusting mechanism 35, and a swash plate 50 as main components. Hereinafter, each component will be described.

As shown in FIG. 2, the case 15 has a first case block 15a and a second case block 15b fixed to the first case block 15a. The first case block 15a and the second case block 15b are fixed to each other by using fasteners such as bolts. The case 15 forms a storage space S inside the case 15. A cylinder block 20, a piston 25, a valve plate 30, a tilt adjusting mechanism 35, and a swash plate 50 are arranged in the accommodation space S.

In the illustrated example, the valve plate 30 is arranged inside the first case block 15a. The first case block 15a is formed with a first oil passage 11 and a second oil passage 12 that communicate with the cylinder chamber 21 of the cylinder block 20 via a valve plate 30. In the drawings, for convenience of explanation, the first oil passage 11 and the second oil passage 12 are represented by lines, but in reality, they are appropriate according to the supply and discharge of hydraulic oil to the cylinder chamber 21 of the cylinder block 20. It has a large internal dimension (inner diameter). The first oil passage 11 and the second oil passage 12 are provided so as to penetrate the case 15 from the inside of the case 15 to the outside of the case 15. The first oil passage 11 and the second oil passage 12 communicate with an actuator, a hydraulic pressure source, etc. provided outside the swash plate type pump 10.

The shaft member 18 is rotatably supported by the case 15 via bearings 19a and 19b. The shaft member 18 can rotate with its central axis as the rotation axis RA. One end of the shaft member 18 is rotatably supported by the first case block 15a via a bearing 19b. The other end of the shaft member 18 is rotatably supported by the second case block 15b via the bearing 19a, passes through a through hole provided in the second case block 15b, and extends out of the case 15. At the portion where the shaft member 18 penetrates the case 15, a seal member is provided between the case 15 and the shaft member 18 to prevent the hydraulic oil from flowing out of the case 15. The portion of the shaft member 18 extending from the case 15 is connected to an input means such as a motor or an engine.

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

When the shaft member 18 and the cylinder block 20 are spline-coupled, the shaft member 18 has spline teeth extending in the axial direction DA parallel to the rotation axis RA on its surface. Then, a part of the spline teeth may be exposed to the accommodation space S in the case 15 without being covered by the cylinder block 20. The spline teeth exposed in the case 15 can promote the discharge of air (air bubbles) remaining in the case 15 as described later. In particular, it is preferable that the spline teeth exposed in the case 15 extend into the central hole 51 of the swash plate 50, which will be described later.

A plurality of cylinder chambers 21 are formed in the cylinder block 20. The plurality of cylinder chambers 21 are arranged at equal intervals along the circumferential direction centered on the rotation axis RA. Each cylinder chamber 21 is open to the side of the swash plate 50 in the axial direction DA parallel to the rotation axis RA. In the illustrated example, each cylinder chamber 21 extends parallel to the axial DA. Further, a connection port 22 is formed corresponding to each cylinder chamber 21. The connection port 22 opens the cylinder chamber 21 to the side of 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 arranged in the cylinder chamber 21. Each piston 25 extends axially DA from the corresponding cylinder chamber 21 toward the swash plate 50. The piston 25 can move in the axial direction DA with respect to the cylinder block 20. That is, the piston 25 can advance toward the swash plate 50 in the axial direction DA to increase the volume of the cylinder chamber 21. Further, the piston 25 can be retracted 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 case 15. The swash plate 50 is arranged in the axial direction DA so as to face the cylinder block 20 and the piston 25. As shown in FIG. 2, the shaft member 18 penetrates the central hole 51 of the swash plate 50. The swash plate 50 has an inner wall surface portion IS that forms (partitions, defines) a central hole 51 through which the shaft member 18 passes, and a contact surface portion CS that comes into contact with the shoe 26 that rotates with the rotation of the shaft member 18. are doing. The contact surface portion CS is located so as to face the cylinder block 20 and the piston 25. The swash plate 50 is supported in the case 15 so that the contact surface portion CS can be inclined with respect to a surface perpendicular to the rotation axis RA. The configuration for holding the swash plate 50 will be described later.

As shown in FIG. 2, a 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. As a specific configuration, the head portion, which is one side end of the piston 25, is formed in a spherical shape. The shoe 26 has a hole that can accommodate approximately half of the spherical head. The shoe 26 holding the head of the piston 25 can move on the contact surface portion CS while contacting the contact surface portion CS of the swash plate 50.

The swash plate pump 10 further has a retainer plate 27 arranged within the case 15. The retainer plate 27 is a ring-shaped and plate-shaped member. The retainer plate 27 is penetrated by the shaft member 18 and supported on the shaft member 18. The support portion 18a that supports the retainer plate 27 of the shaft member 18 is formed in a curved surface shape. Therefore, the retainer plate 27 can be turned while being supported on the shaft member 18. As shown in FIG. 2, the plate-shaped retainer plate 27 is inclined along the contact surface portion CS of the swash plate 50 and is in contact with the shoe 26.

Further, a piston pressing member 28 including a spring or the like is provided between the shaft member 18 and the retainer plate 27. The retainer plate 27 is pressed toward the swash plate 50 in the axial direction DA by the piston pressing member 28. As a result, the retainer 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 has a spring member 28a supported by the cylinder block 20 and a pin 28b located between the spring member 28a and the support member 18a. The spring member 28a presses the support member 18a against the retainer plate 27 via the pin 28b, and as a result, the shoe 26 is pressed toward the swash plate 50.

The valve plate 30 is fixed to the first case block 15a. That is, the valve plate 30 is stationary while the cylinder block 20 is rotating together with the shaft member 18. The valve plate 30 is formed with two or more ports (not shown). Each port communicates with the first oil passage 11 or the second oil passage 12. For example, the port is formed along an arc centered on the rotation axis RA, and as the cylinder block 20 rotates, the port faces the connection port 22 corresponding to each cylinder chamber 21 in order. As a result, each cylinder chamber 21 can switch the connection with the first oil passage 11 and the second oil passage 12 according to the rotation state of the cylinder block 20.

Here, the operation of the swash plate type pump 10 will be described. The shaft member 18 rotates about the rotation axis RA by a rotation driving force from an input means such as a motor or an engine (not shown). At this time, as the cylinder block 20 rotates, the piston 25 advances so as to protrude from the cylinder block 20 and then retracts into the cylinder block 20. The volume of the cylinder chamber 21 changes due to the advance movement and the backward movement of the piston 25.

While the piston 25 retracts from the position where it extends most from the cylinder chamber 21 (top dead center) to the position where it enters the cylinder chamber 21 most (bottom dead center), the cylinder chamber 21 accommodating the piston 25 Capacity is reduced. During this period, the cylinder chamber 21 accommodating the retracting piston 25 is connected to, for example, the first oil passage 11 via a port (not shown) of the valve plate 30, and hydraulic oil is discharged from the cylinder chamber 21. .. The first oil passage 11 is connected to an external actuator or the like as a flow path on the high pressure side.

On the other hand, while the piston 25 advances from the bottom dead center to the top dead center, the capacity of the cylinder chamber 21 accommodating the piston 25 increases. During this period, the cylinder chamber 21 accommodating the moving piston 25 is connected to, for example, the second oil passage 12 via a port (not shown) of the valve plate 30, and the hydraulic oil is sucked into the cylinder chamber 21 for at least a part of the period. To do. The second oil passage 12 is connected to a tank or the like for storing hydraulic oil as a flow path on the low pressure side.

In the above swash plate type pump 10, the contact surface portion CS of the swash plate 50 limits the amount of protrusion of the piston 25 from the cylinder block 20. Therefore, the inclination of the swash plate 50, more precisely expressed, depends on the size of the inclination angle θi (see FIG. 2) of the contact surface portion CS of the swash plate 50 with respect to the surface perpendicular to the axial direction DA. The reciprocating stroke of the piston 25 along the direction DA is determined. Then, the output of the swash plate type pump 10 can be changed by changing the inclination of the swash plate 50, that is, by inclining the swash plate 50. Specifically, when the inclination of the swash plate 50 increases, in other words, when the inclination angle θi increases, the output of the swash plate pump 10 increases. When the inclination of the swash plate 50 becomes small, in other words, when the inclination angle θi becomes small, the output of the swash plate pump 10 decreases. When the contact surface portion CS of the swash plate 50 is perpendicular to the axial direction DA, that is, when the inclination angle θi is 0 °, theoretically, no output can be obtained from the swash plate type pump 10.

Therefore, in the illustrated swash plate type pump 10, the swash plate 50 is held so as to be tiltable, that is, the tilt angle θi formed by the contact surface portion CS with respect to the axial direction DA is mutably held. Hereinafter, a configuration for holding the swash plate 50 in the case 15 so as to be tiltable will be described.

As shown in FIG. 2, the swash plate type pump 10 has a support member 70 that supports the swash plate 50 so that the inclination of the swash plate 50 can be changed, that is, a support member 70 that supports the swash plate 50 so as to be tiltable. have. As shown in FIG. 4, the support member 70 has a base portion 72 fixed to the case 15 and a swash plate support portion 73 provided on the base portion 72. A central through hole 71 through which the shaft member 18 penetrates is formed in the base portion 72. A first swash plate support portion 73A and a second swash plate support portion 73B are provided on the base portion 72 with a central through hole 71 interposed therebetween. The shaft member 18 passes between the two swash plate support portions 73A and 73B and penetrates the central through hole 71. Each swash plate support portion 73 is formed with a receiving recess 74 that receives a bulge portion 54 of the swash plate 50, which will be described later. The receiving recess 74 has a shape corresponding to a part of the side surface of the cylinder (for example, the side surface of the semi-cylinder). In the illustrated example, the support member 70 is formed as a separate body from the case 15, and is fixed to the case 15 via a fixture or the like. However, the present invention is not limited to this example, and the support member 70 may be integrally formed with the second case block 15b as a part of the case 15, for example, as a part of the second case block 15b.

On the other hand, as shown in FIG. 2, the swash plate 50 has a supported portion 53 arranged on the swash plate supporting portion 73 of the support member 70. The supported portion 53 includes a bulging portion 54 having a shape complementary to the receiving recess 74. The bulging portion 54 has a shape corresponding to a part of a cylinder (for example, a semi-cylinder). The swash plate 50 has a first supported portion 53A and a second supported portion 53B arranged apart from each other in the depth direction of the paper surface of FIG. The shaft member 18 passes between the two supported portions 53A and 53B and penetrates the central hole 51. The first supported portion 53A is supported by the first swash plate supporting portion 73A, and the second supported portion 53B is supported by the second swash plate supporting portion 73B.

In this example, the swash plate support portion 73 of the support member 70 has a support surface 75 along an arc in the receiving recess 74. On the other hand, the supported portion 53 of the swash plate 50 has a supported surface 55 along an arc. When the supported portion 53 is arranged in the receiving recess 74 of the swash plate supporting portion 73, the supported surface 55 of the supported portion 53 contacts the support surface 75 of the swash plate supporting portion 73, particularly on a curved surface. Can be done. The swash plate 50 including the supported portion 53 is covered by the supported portion 53 sliding with respect to the swash plate supporting portion 73 in the receiving recess 74, that is, moving (or sliding) while contacting the swash plate supporting portion 73. It rotates with respect to the support member 70 about the center of the arc defined by the support surface 55 and the support surface 75 as an axis. Although not particularly limited, the axis of this tilting operation may be located on the contact surface portion CS of the swash plate 50. With such a 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.

Further, as shown in FIG. 2, the swash plate type pump 10 further has a tilt adjusting mechanism 35 for controlling the inclination of the contact surface portion CS of the swash plate 50. In the illustrated example, the tilt adjusting mechanism 35 includes a swash plate pressing member 36 and a swash plate control device 37. Hereinafter, the tilt adjusting mechanism 35 will be described.

The swash plate 50 shown in FIG. 3 has a central portion 50a, a first receiving portion 50b, and a second receiving portion 50c. The central portion 50a is arranged between the first receiving portion 50b and the second receiving portion 50c. The central portion 50a is provided with the above-mentioned central hole 51, contact surface portion CS, and bulging portion 54. The first receiving portion 50b and the second receiving portion 50c are portions extending to opposite sides from the central portion 50a, respectively.

The swash plate pressing member 36 and the swash plate control device 37 of the tilt adjusting mechanism 35 push the swash plate 50 so as to tilt in opposite directions to each other. The swash plate 50 is held at a constant tilt position by balancing the force pushed by the swash plate pressing member 36 and the force pushed by the swash plate control device 37. In the illustrated example, the swash plate pressing member 36 contacts the first receiving portion 50b of the swash plate 50 and pushes the swash plate 50 so as to tilt in the counterclockwise direction in FIG. The swash plate control device 37 contacts the second receiving portion 50c of the swash plate 50 and pushes the swash plate 50 so as to tilt in the clockwise direction in FIG.

The swash plate pressing member 36 is supported by the first case block 15a of the case 15. The swash plate pressing member 36 is composed of, for example, a compression spring or the like. Therefore, the swash plate pressing member 36 presses the swash plate 50 with a restoring force corresponding to its deformation force.

On the other hand, the swash plate control device 37 is configured as an adjustment actuator 38 and has a control piston 39. The control piston 39 can approach the swash plate 50 (forward) and move away from the swash plate 50 (backward) along the axial direction DA. The control piston 39 pushes the second receiving portion 50c of the swash plate 50. The control piston 39 is driven by, for example, hydraulic pressure. The force with which the control piston 39 pushes the second receiving portion 50c is adjustable. That is, the inclination angle θi of the swash plate 50 can be controlled by adjusting the force output by the swash plate control device 37. Here, the inclination angle θi is formed by the inclination angle of the swash plate 50 with respect to the plane perpendicular to the axial direction DA, which is the operating direction of the piston 25, that is, the contact surface portion CS of the swash plate 50 with respect to the plane perpendicular to the axial direction DA. It is an angle (see FIG. 2).

In the illustrated example, when there is no output of the swash plate control device 37, the inclination angle θi becomes the largest, and the swash plate 50 shown in FIG. 1 is in the maximum inclination state. When the control piston 39 of the swash plate control device 37 pushes the second receiving portion 50c of the swash plate 50, the swash plate 50 can be raised from the maximum tilted state and the tilt angle θi can be reduced. Further, by pushing the swash plate 50 with a larger force by the swash plate control device 37, the swash plate 50 stands up and the inclination angle θi becomes 0 ° or the minimum angle close to 0 °.

In the typical example shown, the swash plate 50 can be tilted from the maximum tilted state shown in FIG. 2 to the standing state, and the state shown in FIG. 1 beyond the standing state. Is not intended to tilt to the opposite side. Therefore, in the illustrated typical example, the standing state in which the inclination angle is 0 ° is the minimum inclination state. Then, in such an example, when passing over a region overlapping the one supported portion 53 (the first supported portion 53A in the illustrated example) on the contact surface portion CS of the swash plate 50 in the axial direction DA. , The pressure in the cylinder chamber 21 becomes high and passes over the region overlapping the other supported portion 53 (second supported portion 53B in the illustrated example) on the contact surface portion CS of the swash plate 50 in the axial direction DA. At that time, the pressure in the cylinder chamber 21 becomes low. In other words, one supported portion 53 (first supported portion 53A in the illustrated example) faces the cylinder chamber 21 on the high pressure side in the axial direction DA, and the other supported portion 53 (illustrated example). Then, the second supported portion 53B) faces the cylinder chamber 21 on the low pressure side in the axial direction DA. The piston 25 in the cylinder chamber 21 on the high pressure side moves from the top dead center to the bottom dead center, and the piston 25 in the cylinder chamber 21 on the low pressure side moves from the bottom dead center to the top dead center.

Here, during the operation of the swash plate type pump 10, the swash plate 50 is pushed toward the support member 70 by the pressure of the hydraulic oil in the cylinder chamber 21 containing the piston 25. In the illustrated example, the first supported portion 53A on the high pressure side is pushed toward the first swash plate support portion 73A with a stronger force, and the second supported portion 53B on the low pressure side is pushed with a weaker force. 2 It is pushed toward the swash plate support portion 73B. When the swash plate 50 is pushed toward the support member 70 at a high pressure, the force required for the tilting operation of the swash plate 50 also increases, and the swash plate 50 cannot be tilted smoothly.

On the other hand, as can be understood from FIGS. 3 and 4, a chamber CA is formed between the swash plate 50 and the support member 70. The chamber CA leads to a flow path P formed in the swash plate 50. Here, the flow path P is a flow path of the pressurized hydraulic oil. Therefore, the chamber CA is filled with pressure oil, i.e., pressurized hydraulic oil. Then, the pressure oil in the chamber C pushes the swash plate 50 in a direction away from the swash plate support portion 73 in the axial direction DA, in other words, in a direction approaching the cylinder block 20 and the piston 25 in the axial direction DA. Further, it is possible to form an oil film between the supported surface 55 and the supported surface 75 to avoid direct frictional contact between the swash plate supporting portion 73 and the supported portion 53. By supplying the pressure oil into the chamber CA in this way, the friction between the swash plate 50 and the swash plate support portion 73 can be reduced. As a result, the tilting of the swash plate 50 by the tilt adjusting mechanism 35 can be smoothed.

In the illustrated example, the flow path P leads to the cylinder chamber 21 on the high pressure side. Therefore, the hydraulic 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 is opened at a position facing the cylinder chamber on the high pressure side of the contact surface portion CS. The other end of the flow path P leads to a chamber CA provided between the first supported portion 53A and the first swash plate supporting portion 73A facing the cylinder chamber 21 on the high pressure side of the swash plate 50. The flow path P is a linear passage and can be manufactured 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 of the piston 25 so that the piston through hole 25P is exposed to the contact surface portion CS. Then, as the shoe 26 moves on the contact surface portion CS, the piston through hole 25P faces the opening of the flow path P located on the contact surface portion CS and leads to the flow path P. At this time, the through hole of the ring-shaped portion of the shoe 26 holding the head 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 (see FIG. 4) formed on the support surface 75 of the first swash plate support portion 73A, but regardless of this example, the first supported portion is supported. It may be composed of recesses formed in the supported surface 55 of the portion 53A.

By the way, in the swash plate type pump 10 having the above configuration, the accommodation space S in the case 15 is filled with hydraulic oil. If the swash plate type pump 10 is used with air remaining in the accommodation space S, problems such as abnormal noise, malfunction, and damage may occur. Therefore, air is removed from the inside of the case 15 prior to the use of the swash plate pump 10 after production, prior to the use of the swash plate pump 10 after disassembly and maintenance, or before the use after replacement of the hydraulic oil. This air bleeding is conventionally carried out through the discharge port 13 (see FIG. 1) formed in the case 15.

On the other hand, in the present embodiment, a device is devised to reduce the work load of bleeding air from the inside of the case 15. Specifically, as shown in FIG. 3, the swash plate 50 is provided with a hole 60. One end of the hole 60 is open to the inner wall surface IS, and the other end of the hole 60 is open to the contact surface CS. That is, the hole 60 has a first opening 61 on the inner wall surface portion IS and a second opening 62 on the contact surface portion CS. Then, the second opening 62 communicates with the piston through hole 25P of the piston 25 that moves on the contact surface portion CS together with the shoe 26. Therefore, the hole 60 can be connected to the cylinder chamber 21 of the cylinder block 20 via the passage provided in the shoe 26 and the piston 25.

In particular, in the illustrated example, the second opening 62 is located in the region of the contact surface portion CS facing the cylinder chamber 21 on the low pressure side. The piston 25 held in the cylinder chamber 21 on the low pressure side moves from the bottom dead center that has entered the cylinder chamber 21 most to the top dead center that protrudes most from the cylinder chamber 21. Therefore, the second opening 62 leads to the cylinder chamber 21 of the contact surface portion CS that houses the piston 25 from the bottom dead center to the top dead center. The cylinder chamber 21 on the low pressure side has a negative pressure, and normally sucks hydraulic oil through the valve plate 30. Therefore, since the hole 60 of the swash plate 50 communicates with the cylinder chamber 21 on the low pressure side through the second opening 62, the air remaining in the case 15 can be sucked and discharged from the first opening 61. ..

When the shaft member 18 rotates in the case 15, the hydraulic oil having a specific gravity larger than that of air moves outward in the radial direction by centrifugal force. On the contrary, air having a specific gravity smaller than that of the hydraulic oil moves inward in the radial direction when the shaft member 18 rotates. Here, the radial direction is a direction orthogonal to the central axis RA. The outer side in the radial direction is the side separated from the central axis RA in the radial direction, and the inner side in the radial direction is the side close to the central axis RA in the radial direction. Therefore, when the swash plate type pump 10 starts to operate and the shaft member 18 rotates, the air in the case 15 tends to collect around the shaft member 18.

The first opening 61 of the hole 60 is opened in the central hole 51 of the swash plate 50. The first opening 61 is close to the shaft member 18 and faces the shaft member 18. Therefore, by rotating the shaft member 18, air automatically collects around the shaft member 18, and the air around the shaft member 18 is introduced into the hole 60, the through hole of the shoe 26, and the piston through hole of the piston 25. It can be sucked into the cylinder chamber 21 on the low pressure side via 25P. Then, the air sucked from the accommodation space S into the cylinder chamber 21 is discharged to the outside of the case 15 through, for example, the second oil passage 12. That is, air bleeding can be automatically performed by starting the operation of the swash plate type pump 10. Therefore, it is possible to substantially eliminate the work load of air bleeding. It can be said that such an action / effect is a remarkable action / effect that cannot be predicted by those skilled in the art from the technical level.

Especially in the illustrated example, the holes 60 are open only at both ends. Therefore, air can be sucked into the hole 60 from the first opening 61 of the hole 60 by efficiently utilizing the suction force from the cylinder chamber 21 on the low pressure side. That is, suction can be performed with a strong suction force from the first opening 61 forming one end side of the hole 60 opened in the inner wall surface portion IS. As a result, air can be efficiently evacuated.

Further, the shoe 26 has an outer contour that covers the entire second opening 62 on 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 of the piston 25 and contacts the contact surface portion CS has an outer contour that can cover the entire second opening 62. For example, the width of the shoe 26 along the radial direction is larger than the width along the radial direction of the second opening 62. According to such an example, suction can be performed with a strong suction force from the first opening 61 of the hole 60 opened in the inner wall surface portion IS. As a result, air can be efficiently evacuated.

When the shaft member 18 and the cylinder block 20 are spline-coupled, the shaft member 18 has spline teeth extending in the axial direction DA parallel to the rotation axis RA on its surface. Then, by exposing a part of the spline teeth to the accommodation space S in the case 15 without being covered by the cylinder block 20, centrifugal force can be efficiently applied to the hydraulic oil in the accommodation space S. This makes it possible to promote the radial movement of the hydraulic oil in the accommodation space S. Along with this, the movement of air in the accommodation space S in the radial direction can be promoted, and the air can be efficiently evacuated. Further, when the spline teeth exposed in the case 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 makes it possible to more efficiently suck air from the first opening 61 opened in the central hole 51.

However, the movement of air inward in the radial direction is not limited to the exposed spline teeth, but can also be realized by a convex portion or the like provided on the rotating shaft member 18. Further, the movement of air into the central hole 51 along the axial direction DA is not limited to the exposed spline teeth, and can be realized by a linear convex portion extending in the axial direction DA provided on the rotating shaft member 18. ..

Further, the suction force from the cylinder chamber 21 on the low pressure side becomes large when the change in the volume of the cylinder chamber 21 per unit time becomes large. Therefore, in the plan view of the contact surface portion CS shown in FIG. 5, the piston 25 at the most retracted bottom dead center is housed in the cylinder chamber 21 along the circumferential direction DC centered on the rotation axis RA of the shaft member 18. When the cylinder chamber 21 passes through the intermediate position PM between the bottom dead center position PY and the top dead center position PX accommodating the piston 25 located at the top dead center most protruding from the cylinder chamber 21, the suction force is maximum. It becomes. The second opening 62 of the hole 60 is preferably located within an angle range of less than ± 30 ° from the intermediate position PM in the circumferential direction about the rotation axis RA, from the viewpoint of efficiently bleeding air. It can be said that it is a superior condition.

According to the embodiment described above, the swash plate type pump 10 has a shaft member 18, a cylinder block 20 held by the shaft member 18, and a piston movably arranged in the cylinder chamber 21 of the cylinder block 20. It has a 25, a shoe 26 connected to the end of the piston 25, an inner wall surface portion IS forming a central hole 51 through which the shaft member 18 passes, and a contact surface portion CS that comes into contact with the shoe that rotates with the rotation of the shaft member 18. It has a swash plate 50 and a case 15 that rotatably supports the shaft member 18 and houses the swash plate 50. When the shaft member 18 rotates in the case 15, the hydraulic oil moves outward in the radial direction due to centrifugal force, and air having a specific gravity smaller than that of the hydraulic oil moves inward in the radial direction. On the other hand, the swash plate 50 is provided with a hole 60 opened in the inner wall surface portion IS and the contact surface portion CS. The hole 60 leads to the cylinder chamber 21 on the low pressure side via a passage (through hole) formed in the shoe 26 and a passage (piston through hole 25P) formed in the piston 25. Therefore, the air that has moved inward in the radial direction can be sucked from the first opening 61 of the inner wall surface portion IS and sucked out from the inside of the case 15. That is, when the pump operates, the air inside the case 15 is automatically evacuated.

Although one embodiment has been described by a plurality of specific examples, these specific examples are not intended to limit one embodiment. The above-described embodiment can be implemented in various other specific examples, and various omissions, replacements, changes, additions, and the like can be made without departing from the gist thereof.

Hereinafter, an example of modification will be described 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 the corresponding parts in the above-mentioned specific examples are used for the parts that can be configured in the same manner as the above-mentioned specific examples, and the same reference numerals are used, and duplicate explanations are given. Is omitted.

First, in the above-described embodiment, the flow path P provided in the swash plate 50 faces the position of the contact surface portion CS facing the cylinder chamber 21 on the high pressure side and the cylinder chamber 21 on the high pressure side of the swash plate 50. An example is shown in which a high-pressure side chamber CA provided between the portion (first supported portion 53A) and the swash plate supporting portion 73 (first swash plate supporting portion 73A) extends linearly. In this example, by supplying the pressure oil in the cylinder chamber 21 on the high pressure side to the chamber CA on the high pressure side, the friction between the swash plate 50 and the swash plate support portion 73 is reduced, and the swash plate 50 is tilted smoothly and stably. I made it possible to realize the change. However, not limited to this example, the flow path P having one end opened at a position facing the cylinder chamber 21 on the high pressure side of the contact surface portion CS is not only the high pressure side chamber CA but also the low pressure of the swash plate 50. It may also be connected to the low pressure chamber CB located between the portion facing the cylinder chamber 21 on the side (second supported portion 53B) and the swash plate supporting portion (second swash plate supporting portion 73B). According to such a modification, the tilting operation of the swash plate 50 on the swash plate support portion 73 can be made smoother.

In the example shown in FIG. 6, the flow path P has a high-pressure side flow path PA, a low-pressure side flow path PB, a first relay flow path PC, and a second relay flow path PD. The high-pressure side flow path PA extends linearly between the position of the contact surface portion 57 facing the high-pressure side cylinder chamber 21 and the high-pressure side chamber CA. The high-pressure side flow path PA can be the same as the flow path P of the example shown in FIG. The low pressure side flow path PB extends linearly and leads to the low pressure side chamber CB. The first relay flow path PC extends linearly and leads to the high pressure side flow path PA. In particular, in the illustrated example, the first relay flow path PC intersects the high pressure side flow path PA. The second relay flow path PD extends linearly and leads to the low pressure side flow path PB. In particular, in the illustrated example, the second relay flow path PC intersects the low pressure side flow path PB. Further, the first relay flow path PC and the second relay flow path PC are in communication with each other.

These high-pressure side flow path PA, low-pressure side flow path PB, first relay flow path PC, and second relay flow path PD can be easily formed by machining such as drilling as an example. In the illustrated example, the high pressure side flow path PA penetrates the swash plate 50. The low-pressure side flow path PB is formed by performing machining such as drilling from the side of the supported portion 53, and does not reach the contact surface portion CS. The first relay flow path PC is formed by performing machining such as drilling from the outer surface of the first supported portion 53A, does not penetrate the swash plate 50, and stops in the middle of the swash plate 50. The first relay flow path PC mainly extends in the first supported portion 53A in a direction inclined with respect to the longitudinal direction of the swash plate. The second relay flow path PD is formed by performing machining such as drilling from the outer surface of the second supported portion 53B, does not penetrate the swash plate 50, and stops in the middle of the swash plate 50. The second relay flow path PD mainly extends in the second supported portion 53B in a direction inclined with respect to the longitudinal direction of the swash plate. The first relay flow path PC and the second relay flow path PD are connected to each other at the ends. The first relay flow path PC and the second relay flow path PD extend inclined with respect to the tilt axis of the swash plate 50 so as to bypass the central hole 51. Further, the ends of the first relay flow path PC and the second relay flow path PD on the processing start side are closed by a plug or the like. As a result, the flow path P is open only at the position of the contact surface portion CS facing the cylinder chamber 21 on the high pressure side and the high pressure side chamber CA and the low pressure side chamber CB.

The flow path P interferes with the hole 60 by including the four linearly extending high-pressure side flow paths PA, the low-pressure side flow path PB, the first relay flow path PC, and the second relay flow path PD. However, the flow path P can be easily produced.

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 first supported portion 53A, or may be formed of the first swash plate supporting portion 73A. It may be composed of recesses formed in the support surface 75, and further, a recess formed in the supported surface 55 of the first supported portion 53A and a recess formed in the support surface 75 of the first swash plate support portion 73A. It may be configured by a combination with. Further, the low pressure side chamber CB may be composed of recesses formed in the supported surface 55 of the second supported portion 53B, or may be formed by recesses formed in the support surface 75 of the second swash plate supporting portion 73B. It may be configured, and may be further configured by a combination of a recess formed on the supported surface 55 of the second supported portion 53B and a recess formed on the supporting surface 75 of the second swash plate supporting portion 73B. Good.

Further, in the above-mentioned specific example, the hole 60 is opened 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 also leads to the discharge port 13 provided in the case 15. You may. According to such an example, air can be evacuated not only from the cylinder chamber 21 on the low pressure side but also from the discharge port 13. Therefore, air bleeding can be performed more efficiently and more reliably.

Further, in the above-mentioned specific example, an example is shown in which the second opening 62 of the hole 60 is provided at a position facing the cylinder chamber 21 on the low pressure side of the contact surface portion CS, but the present invention is not limited to this example. The second opening 62 of the hole 60 may be provided at a position facing the cylinder chamber 21 on the high pressure side of the contact surface portion CS. In this example, pressure oil (oil) is supplied from the cylinder chamber 21 into the hole 60 as the shaft member 18 rotates. The supplied pressure oil is discharged into the accommodation space S of the case 15 through the first opening 61. By discharging the pressure oil, the bubbles staying around the shaft member 18 can be moved by stirring. Thereby, for example, air bleeding can be performed more efficiently and more reliably through the discharge port 13 provided in the case 15.

10 Swash plate pump 13 Discharge port 15 Case 18 Shaft member 20 Cylinder block 21 Cylinder chamber 25 Piston 26 Shoe 30 Valve plate 35 Tilt adjustment mechanism 50 Swash plate 51 Central hole 60 Hole 61 1st opening 62 2nd opening 73 Swash plate support Part CM Construction machine IS Inner wall surface part CS Contact surface part P Flow path CA High pressure side chamber

Claims (7)

Shaft member and
The cylinder block held by the shaft member and
A piston movably arranged in the cylinder chamber of the cylinder block and
The shoe connected to the piston and
It has an inner wall surface portion that forms a central hole through which the shaft member passes, and a contact surface portion that comes into contact with a shoe that rotates with the rotation of the shaft member, one end of which opens into the inner wall surface portion and the other end of the contact. A swash plate that is open on the surface and has a hole that leads to the cylinder chamber through a passage provided in the piston.
A swash plate type pump including a case for rotatably supporting the shaft member and accommodating the swash plate. The swash plate type pump according to claim 1, wherein the shoe has an outer contour that covers the entire opening on the other end side of the hole of the swash plate. The swash plate type pump according to claim 1 or 2, wherein a discharge port leading to the hole of the swash plate is provided in the case. The case has a swash plate support portion that supports the swash plate.
The hole is opened at a position facing the cylinder chamber on the low pressure side of the contact surface portion.
One end is opened at a position facing the cylinder chamber on the high pressure side of the contact surface portion, and the other end is located between the portion of the swash plate facing the cylinder chamber on the low pressure side and the swash plate support portion. The swash plate type pump according to any one of claims 1 to 3, wherein a flow path opened in the chamber is provided on the swash plate. The swash plate type pump according to any one of claims 1 to 4, wherein the holes are opened only at both ends. A construction machine comprising the swash plate pump according to any one of claims 1 to 5. The inner wall surface that forms the central hole through which the shaft member passes,
A swash plate pump provided with an annular contact surface portion that comes into contact with a shoe that is located around the central hole and holds the piston, and one end side of which is the other end side of the hole opened in the inner wall surface portion. Swash plate for.