KR20200115227A - Swash plate, swash plate type pump and construction machine - Google Patents

Abstract

An object of the present invention is to reduce burden of bleeding air in a swash plate pump. To this end, the swash plate pump (10) according to the present invention has: a shaft member (18); a cylinder block (20) held by the shaft member; a piston (25) disposed movably in a cylinder chamber (21) of the cylinder block; a shoe (26) connected to an end of the piston; a swash plate (50) having an inner wall surface (IS) forming a central hole (51) through which the shaft member passes, and a contact surface (CS) contacting the shoe rotating in association with rotation of the shaft member; and a case (15) rotationally supporting the shaft member and accommodating the swash plate. In addition, provided is a hole (60) of which one end is open on the inner wall surface and the other end is open on the contact surface and which communicates with the cylinder chamber through a passage (25P) provided in the piston.

Description

Swash plate, swash plate type pump and construction machine {SWASH PLATE, SWASH PLATE TYPE PUMP AND CONSTRUCTION MACHINE}

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

For example, as disclosed in Patent Document 1 (JPH2-26772A), a swash plate type pump is used in various technical fields. Before the swash plate type pump is actually used, the hydraulic oil is filled in the case. At this time, the air in the case is removed using the air bleeding port provided in the case. This air bleeding operation is carried out whenever hydraulic oil is replaced by inspection or the like. Therefore, in the swash plate type pump, it is desired to reduce the work burden of releasing air.

The present invention has been made in view 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.

Inclined plate pump according to the present invention,

Shaft member,

A cylinder block held by the shaft member,

A piston disposed to be movable into the cylinder chamber of the cylinder block,

A shoe connected to the piston,

The shaft member has an inner wall surface portion defining a central hole through which the shaft member passes, and a contact surface portion contacting a shoe that rotates along with the rotation of the shaft member, and one end is opened to the inner wall surface and the other end is opened to the contact surface. A swash plate provided with a hole through the cylinder chamber through a passage provided in the piston,

And a case for rotatably supporting the shaft member and accommodating the swash plate.

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

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

In the swash plate type pump according to the present invention,

The case has a swash plate support portion for supporting the swash plate,

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

One end of the contact surface portion is opened at a position facing the cylinder chamber on the high pressure side, the other end of the swash plate is a flow path opened to the chamber positioned between the portion facing the cylinder chamber on the low pressure side and the swash plate support portion, the It may be provided on the swash plate.

In the swash plate type pump according to the present invention,

The flow path is,

A high pressure side flow path extending in a straight line between a position of the contact surface portion facing the cylinder chamber on the high pressure side, a portion facing the cylinder chamber on the high pressure side of the swash plate and a high pressure side chamber provided between the swash plate support portion,

A linear low pressure side flow path through 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,

The low-pressure side flow path and a 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 hole may be opened only at both ends.

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

The swash plate according to the present invention,

An inner wall surface portion forming a central hole through which the shaft member passes,

An annular contact surface portion provided with an opening positioned around the central hole and in contact with a shoe holding the piston and having one end thereof serving as the other end side of the hole opened in the inner wall surface portion is provided.

Advantageous Effects of Invention According to the present invention, the burden of bleeding air in the swash plate pump can be greatly reduced.

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 type pump can be applied.
2 is a longitudinal cross-sectional view showing an example of a swash plate type pump that can be applied to the construction machine of FIG. 1.
3 is a perspective view showing a swash plate of the swash plate type pump of FIG. 2.
4 is a perspective view showing a swash plate support portion of the swash plate type pump of FIG. 2.
5 is a plan view showing a swash plate contact surface of FIG. 3.
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. In addition, elements shown in each of the drawings may include elements that are shown and differ in size and scale from those in practice in order to facilitate understanding.

The swash plate type pump 10 described below is a so-called variable displacement type swash plate type piston pump. The swash plate pump 10 sucks hydraulic oil into a cylinder chamber 21 to be described later, and discharges the hydraulic oil from the cylinder chamber 21. More specifically, by rotating the shaft member 18 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 cylinder block 20 The piston 25 reciprocates by rotation of. In accordance with the reciprocating motion of the piston 25, the hydraulic oil is sucked into some 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 drive device provided in a construction machine, but may be applied to other uses, and its use is not particularly limited. 1 shows a hydraulic excavator 90 as an example of a construction machine CM to which the swash plate pump 10 according to the present embodiment can be applied.

In general, the hydraulic excavator 90 includes a lower frame 91 having a crawler, an upper frame 92 provided to be pivotable with respect to the lower frame 91, and a boom installed on the upper frame 92 ( 93), an arm 94 installed on the boom 93, and a bucket 95 installed on the arm 94. The hydraulic cylinders 96A, 96B, and 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 pivoted, the rotational driving force from the pivoting 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 turning device 97 and the traveling device 98 are configured by a hydraulic motor that outputs rotation when hydraulic pressure is input. The swash plate pump 10 is in charge of supplying hydraulic oil to hydraulic actuators such as hydraulic cylinders 96A, 96B, and 96C, turning device 97, and traveling device 98.

Next, the swash plate pump 10 will be described.

The swash plate type pump 10 is a case 15, a shaft member 18, a cylinder block 20, a piston 25, a valve plate 30, a tilting adjustment mechanism 35, and a swash plate ( 50). Hereinafter, each component will be described.

As shown in Fig. 2, the case 15 has a first case block 15a, a first case block 15a, and a fixed second case block 15b. The first case block 15a and the second case block 15b are fixed to each other using fasteners such as bolts. The case 15 has an accommodation space S formed therein. In the accommodation space S, a cylinder block 20, a piston 25, a valve plate 30, a tilting adjustment mechanism 35, and a swash plate 50 are arranged.

In the illustrated example, the valve plate 30 is disposed inside the first case block 15a. In the first case block 15a, a first flow path 11 and a second flow path 12 that communicate with the cylinder chamber 21 of the cylinder block 20 through the valve plate 30 are formed. In the drawings, for convenience of explanation, the first flow path 11 and the second flow path 12 are indicated by lines, but in reality, supply and discharge of hydraulic oil to the cylinder chamber 21 of the cylinder block 20 It has an appropriate inner dimensioning method (inner diameter) according to. The first flow path 11 and the second flow path 12 are provided through the case 15 from the inside of the case 15 to the outside of the case 15. The first flow path 11 and the second flow path 12 communicate with an actuator or a hydraulic source 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 its central axis as a rotation axis RA. One end of the shaft member 18 is rotatably supported by a 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 through the bearing 19a, and extends out of the case 15 through the through hole provided in the second case block 15b. Has been. In a portion where the shaft member 18 passes through the case 15, a sealing 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 input means such as a motor or an engine, for example.

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

Further, 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. Further, 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 (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 to 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 about the rotation axis RA. Each cylinder chamber 21 is open on 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 direction 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.

Corresponding to each cylinder chamber 21, a piston 25 is provided. A part of each piston 25 is disposed in the cylinder chamber 21. Each piston 25 extends from the corresponding cylinder chamber 21 toward the swash plate 50 in the axial direction DA. The piston 25 can move in the axial direction DA with respect to the cylinder block 20. That is, the piston 25 advances toward the swash plate 50 in the axial direction DA, and the volume of the cylinder chamber 21 can be enlarged. Further, the piston 25 is retracted toward the valve plate 30 in the axial direction DA, so that the volume of the cylinder chamber 21 can be reduced.

The swash plate 50 is supported in the case 15. The swash plate 50 is disposed opposite the cylinder block 20 and the piston 25 in the axial direction DA. As shown in FIG. 2, the shaft member 18 penetrates the central hole 51 of the swash plate 50. The swash plate 50 includes an inner wall surface portion IS forming a central hole 51 through which the shaft member 18 passes (division, partition formation), a shoe 26 that rotates with the rotation of the shaft member 18, and It has a contact surface part CS that contacts. The contact surface portion CS is positioned 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 the surface perpendicular to the rotation axis RA. The configuration for holding the swash plate 50 will be described later.

As shown in FIG. 2, the shoe 26 is provided on the contact surface part CS of the swash plate 50. The shoe 26 holds the head (end) of the piston 25. As a specific configuration, the head portion serving as one end of the piston 25 is formed in a spherical shape. The shoe 26 has a hole capable of receiving approximately half of the spherical head portion. The shoe 26 holding the head portion of the piston 25 is movable over the contact surface portion CS while contacting the contact surface portion CS of the swash plate 50.

The swash plate type pump 10 further has a retainer plate 27 disposed in the case 15. The retainer plate 27 is a ring-shaped and plate-shaped member. The retainer plate 27 penetrates by the shaft member 18 and is 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 shape. For this reason, the retainer plate 27 can change its direction while being supported on the shaft member 18. As shown in FIG. 2, the plate-shaped retainer plate 27 is inclined so as to follow the contact surface portion CS of the swash plate 50 and is in contact with the shoe 26.

Further, between the shaft member 18 and the retainer plate 27, a piston pressing member 28 including a spring or the like is provided. The retainer plate 27 is pressed against the side of 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 includes a spring member 28a supported on the cylinder block 20 and a pin 28b positioned between the spring member 28a and the support member 18a. I have. The spring member 28a urges the support member 18a to the retainer plate 27 via the pin 28b, and consequently urges the shoe 26 toward the swash plate 50.

The valve plate 30 is fixed to the first case block 15a. That is, the valve plate 30 is stopped while the cylinder block 20 is rotating together with the shaft member 18. In the valve plate 30, two or more ports (not shown) are formed. Each port communicates with the first flow path 11 or the second flow path 12. The ports are formed along a circular arc centered on the rotation axis RA, for example, and accompanied by the rotation of the cylinder block 20, they face the connection ports 22 corresponding to each cylinder chamber 21 in order. . As a result, in accordance with the rotational state of the cylinder block 20, each cylinder chamber 21 switches the connection between the first flow path 11 and the second flow path 12.

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

A cylinder in which the piston 25 is retracted from the most extended position (top dead center) from the cylinder chamber 21 to the most entered position (bottom dead center) in the cylinder chamber 21, while retreating. The capacity of the yarn 21 decreases. During at least a portion of the period, the cylinder chamber 21 accommodating the piston 25 during retraction is connected to, for example, the first flow path 11 through a port not shown by the valve plate 30, and the cylinder The hydraulic oil is discharged from the seal 21. The first flow path 11 is a flow path on the high-pressure side and is connected to an external actuator or the like.

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 at least a portion of the period, the cylinder chamber 21 accommodating the piston 25 during advancing is connected to, for example, the second flow path 12 through a port not shown by the valve plate 30, and the cylinder Hydraulic oil is sucked into the chamber 21. The second flow path 12 is a flow path on the low pressure side and is connected to a tank or the like for storing hydraulic oil.

In the swash plate type pump 10 described above, 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 of the contact surface portion CS of the swash plate 50 with respect to the plane perpendicular to the axial direction DA (see Fig. 2), the axial direction The stroke of the reciprocating movement of the piston 25 along DA is determined. Further, by changing the inclination of the swash plate 50, that is, by tilting the swash plate 50, the output of the swash plate type pump 10 can be changed. 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 type pump 10 increases. When the inclination of the swash plate 50 decreases, in other words, when the inclination angle θi decreases, the output of the swash plate type 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 becomes 0°, theoretically, no output is obtained from the swash plate type pump 10.

For this reason, in the illustrated swash plate type pump 10, the swash plate 50 is held in a tiltable manner, that is, the inclination angle θi formed by the contact surface portion CS with respect to the axial direction DA can be changed. 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 allows the support member 70 supporting the swash plate 50, that is, the swash plate 50 to be tilted so that the inclination of the swash plate 50 can be changed. It has a supporting member 70 to support. As shown in FIG. 4, the support member 70 has a base 72 fixed to the case 15 and a swash plate support part 73 provided on the base 72. In the base 72, a central through hole 71 through which the shaft member 18 passes is formed. On the base 72, a first swash plate support part 73A and a second swash plate support part 73B are provided with the center through hole 71 therebetween. The shaft member 18 passes between the two swash plate support portions 73A and 73B and penetrates the center through hole 71. Each swash plate support part 73 is formed with a receiving concave part 74 for receiving the bulging part 54 to be described later of the swash plate 50. 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 semicircular column). 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 through a fastener or the like. However, it is not limited to this example, and the support member 70 is formed integrally with the second case block 15b as a part of the case 15, for example, as a part of the second case block 15b. It may be.

On the other hand, as shown in FIG. 2, the swash plate 50 has a supported portion 53 disposed on the swash plate support portion 73 of the support member 70. The supported portion 53 includes a receiving concave portion 74 and a bulging portion 54 having a complementary shape. The bulging portion 54 has a shape corresponding to a part of a cylinder (for example, a semicircular column). The swash plate 50 has a 1st supported part 53A and a 2nd supported part 53B arrange|positioned apart in the depth direction of the paper 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 support portion 73A, and the second supported portion 53B is supported by the second swash plate support 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 accommodation 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 disposed in the receiving recess 74 of the swash plate support portion 73, the supported surface 55 of the supported portion 53 contacts the support surface 75 of the swash plate support portion 73, In particular, it can make surface contact on a curved surface. The supported part 53 slides with respect to the swash plate support part 73 within the receiving concave part 74, that is, the swash plate 50 including the supported part 53 by moving (or slidingly) while in contact Silver rotates with respect to the support member 70 with the center of an arc defined by the sebum surface 55 and the support surface 75 as an axis. Although not particularly limited, the axis of the tilting operation may be positioned 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, the swash plate type pump 10 further has a tilting adjustment mechanism 35 for controlling the inclination of the contact surface portion CS of the swash plate 50 as shown in FIG. 2. In the illustrated example, the tilting adjustment mechanism 35 includes a swash plate pressing member 36 and a swash plate control device 37. Hereinafter, the tilting adjustment mechanism 35 will be described.

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

The swash plate pressing member 36 and the swash plate control device 37 of the tilting adjustment mechanism 35 press and hold the swash plate 50 so as to tilt in opposite directions to each other. The swash plate 50 is held at a constant tilting position by balancing a force pressed by the swash plate pressing member 36 and a force pressed from the swash plate control device 37. In the illustrated example, the swash plate pressing member 36 contacts the first hydraulic part 50b of the swash plate 50 and presses the swash plate 50 so as to tilt in the counterclockwise direction in FIG. 2. The swash plate control device 37 contacts the second hydraulic part 50c of the swash plate 50 and presses the swash plate 50 so as to tilt in the clockwise direction in FIG. 2.

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 constituted by, for example, a compression spring. Accordingly, 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 as an adjustment actuator 38 and has a control piston 39. The control piston 39 is capable of approaching the swash plate 50 (forward) and spaced apart from the swash plate 50 (retreat) along the axial direction DA. The control piston 39 presses the second hydraulic power portion 50c of the swash plate 50. The control piston 39 is driven by hydraulic pressure, for example. And, the force by which the control piston 39 presses the 2nd hydraulic part 50c is adjustable. That is, by adjusting the force output from the swash plate control device 37, the swash plate 50 can control the inclination angle θi. Here, the inclination angle θi is the inclination angle of the swash plate 50 with respect to the plane perpendicular to the axial direction DA, which is the operation direction of the piston 25, that is, the contact surface CS of the swash plate 50 with respect to the vertical plane Means the 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 a maximum inclined state. When the control piston 39 of the swash plate control device 37 presses the second hydraulic part 50c of the swash plate 50, the swash plate 50 is erected from the maximum inclined state, and the inclination angle θi can be reduced. . Further, by pressing the swash plate 50 with a greater force by the swash plate control device 37, the swash plate 50 stands up and the tilt angle θi becomes a minimum angle close to 0° or 0°.

In addition, in the illustrated exemplary embodiment, the swash plate 50 is capable of tilting from the maximum inclined state shown in FIG. 2 to the upright state, and the inclined side is inclined to a side opposite to the state shown in FIG. 1 beyond the standing state. Is not intended. Therefore, in the illustrated exemplary example, the upright state in which the inclination angle becomes 0° becomes the minimum inclination state. And, in this example, when passing over a region overlapping the axial direction DA with one supported portion 53 (in the illustrated example, the first supported portion 53A) on the contact surface portion CS of the swash plate 50 The pressure in the cylinder chamber 21 becomes high, and the other supported portion 53 (in the illustrated example, the second supported portion 53B) on the contact surface portion CS of the swash plate 50 and the axial direction DA When passing over the overlapping area, the pressure in the cylinder chamber 21 becomes low. In other words, one supported portion 53 (in the illustrated example, the first supported portion 53A) faces the cylinder chamber 21 on the high-pressure side in the axial direction DA, and the other supported portion 53 (In the illustrated example, 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 pressed toward the support member 70 by the hydraulic oil pressure in the cylinder chamber 21 accommodating the piston 25. In the illustrated example, the first supported portion 53A serving as the high pressure side is pressed toward the first swash plate support portion 73A with a stronger force, and the second supported portion 53B serving as the low pressure side is the second swash plate support portion with a weaker force. Press towards (73B). In addition, when the swash plate 50 is pressed toward the support member 70 with high pressure, the force required for the tilting operation of the swash plate 50 also increases, so that the swash plate 50 cannot be smoothly tilted.

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 communicates with the flow path P formed in the swash plate 50. Here, the flow path P is a flow path of the pressurized hydraulic oil. Thus, the chamber CA is filled with hydraulic oil, that is, pressurized hydraulic oil. And, the pressure oil in the chamber CA is in the direction away from the swash plate support part 73 in the axial direction DA, in other words, in the direction approaching the cylinder block 20 and the piston 25 in the axial direction DA, the swash plate Press 50. Further, it is also possible to form an oil film between the supported surface 55 and the support surface 75 and avoid direct frictional contact between the swash plate support part 73 and the supported part 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 part 73 can be reduced. Thereby, the tilting of the swash plate 50 by the tilting adjustment mechanism 35 can be smoothed.

In the illustrated example, the flow path P is made to pass through 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 communicates with the chamber CA provided between the first supported portion 53A and the first swash plate support portion 73A facing the cylinder chamber 21 on the high pressure side of the swash plate 50. The flow path P is a straight path, and can be manufactured by machining such as drilling. In addition, 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 as to expose the piston through hole 25P 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 positioned on the contact surface portion CS, and passes through the flow path P. At this time, the through hole in the ring-shaped portion of the shoe 26 that holds the head portion of the piston 25 also functions as a part of the pressure oil passage. Further, in the illustrated example, the chamber CA is configured as a concave portion (see Fig. 4) formed in the support surface 75 of the first swash plate support portion 73A, but not by this example, the first supported portion ( It may be constituted by a recess formed in the sebum surface 55 of 53A).

By the way, in the swash plate type pump 10 having the above configuration, hydraulic oil is filled in the accommodation space S in the case 15. If the swash plate type pump 10 is used with air remaining in the accommodation space S, problems such as generation of joints, poor operation, and further damage may occur. Therefore, prior to use after manufacture of the swash plate type pump 10, before use after disassembly and maintenance of the swash plate type pump 10, or before use after exchange of hydraulic oil, air is removed from the case 15. All. This air evacuation is conventionally performed through a discharge port 13 (see FIG. 1) formed in the case 15.

On the other hand, in this embodiment, a design is made to reduce the work burden of releasing air from the case 15. Specifically, as shown in FIG. 3, a hole 60 is provided in the swash plate 50. One end of the hole 60 is opened in the inner wall surface portion IS, and the other end of the hole 60 is opened in the contact surface portion CS. That is, the hole 60 has the 1st opening 61 on the inner wall surface part IS, and the 2nd opening 62 on the contact surface part CS. Then, the second opening 62 passes through the piston through-hole 25P of the piston 25 moving on the contact surface portion CS together with the shoe 26. Accordingly, this hole 60 can be made to pass through the passage provided in the shoe 26 and the piston 25 to the cylinder chamber 21 of the cylinder block 20.

In particular, in the illustrated example, the second opening 62 is located in a region facing the cylinder chamber 21 on the low pressure side of the contact surface portion CS. The piston 25 held in the cylinder chamber 21 on the low pressure side moves from the bottom dead center most entered into the cylinder chamber 21 to the top dead center protruding most from the cylinder chamber 21. Accordingly, the second opening 62 passes through the cylinder chamber 21 accommodating the piston 25 from the bottom dead center to the top dead center of the contact surface portion CS. The cylinder chamber 21 on the low pressure side becomes negative pressure, and normally sucks hydraulic oil through the valve plate 30. Therefore, the hole 60 of the swash plate 50 passes through the second opening 62 to the cylinder chamber 21 on the low-pressure side, so that the air remaining in the case 15 is sucked from the first opening 61. It becomes possible to discharge.

In the case 15, when the shaft member 18 rotates, the hydraulic oil having a higher specific gravity compared to air moves outward in the radial direction by centrifugal force. Conversely, 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. And the outer side in the radial direction means a side separated from the central axis RA in the radial direction, and the inner side in the radial direction means a side close to the central axis RA in the radial direction. Therefore, when the swash plate type pump 10 starts operation and the shaft member 18 rotates, the air in the case 15 tends to collect around the shaft member 18.

And, in the center hole 51 of the swash plate 50, the 1st opening 61 of the hole 60 is opened. This first opening 61 is close 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 is transferred to the hole 60 and the through hole of the shoe 26. And suction into the cylinder chamber 21 on the low-pressure side through the piston through-hole 25P of the piston 25. Then, the air sucked into the cylinder chamber 21 from the accommodation space S is discharged to the outside of the case 15 through the second flow path 12, for example. That is, by starting the operation of the swash plate type pump 10, air can be removed automatically. Therefore, it becomes possible to substantially eliminate the work burden of releasing air. Such an action effect can be said to be a remarkable action effect that a person skilled in the art cannot predict from the skill level.

In particular, in the illustrated example, the hole 60 is open only at both ends. Accordingly, air can be sucked into the hole 60 from the first opening 61 of the hole 60 by efficiently using 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 of the hole 60 opened in the inner wall surface part IS. Thereby, air can be efficiently evacuated.

In addition, the shoe 26 has an outer contour covering the whole of the second opening 62 serving as 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 contacts the contact surface portion CS has an outer contour capable of covering the entire second opening 62. For example, the width of the shoe 26 along the radial direction is larger than the width of the second opening 62 along the radial direction. According to this 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. Thereby, air can be efficiently evacuated.

Further, 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. In addition, a part of the spline teeth is not covered with the cylinder block 20 and is exposed to the accommodation space S in the case 15, whereby centrifugal force can be efficiently applied to the hydraulic oil in the accommodation space S. Thereby, it is possible to promote the movement of the hydraulic oil to the outside in the radial direction in the accommodation space S. Along with this, it is possible to promote the movement of the air in the accommodation space S to the inside in the radial direction, so that air can be efficiently evacuated. Further, when the spline teeth exposed in the case 15 extend into the center hole 51 of the swash plate 50, air is guided into the center hole 51 by the spline teeth. Also by this, air can be sucked more efficiently from the first opening 61 opened in the central hole 51.

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

Further, the suction force from the cylinder chamber 21 on the low pressure side becomes large when the change per unit time of the volume of the cylinder chamber 21 increases. Therefore, when viewed from the plane of the contact surface portion CS shown in Fig. 5, the piston at the bottom dead center most retracted in the cylinder chamber 21 along the circumferential direction DC around the rotation axis RA of the shaft member 18 ( When the cylinder chamber 21 passes the intermediate position PM of the bottom dead center position PY accommodating 25) and the top dead center position PX accommodating the piston 25 located at the top dead center protruding from the cylinder chamber 21 The suction power is maximized. In addition, it is preferable that the second opening 62 of the hole 60 is in a position within the angular range of less than ±30° from the intermediate position PM in the circumferential direction with the rotation axis RA as the center. It can be said that it is a predominant condition in terms of implementation.

According to the embodiment described above, the swash plate type pump 10 includes the shaft member 18, the cylinder block 20 held by the shaft member 18, and the cylinder chamber 21 of the cylinder block 20. ), the piston 25 disposed to be movable, the shoe 26 connected to the end of the piston 25, and the inner wall surface part IS and the shaft member forming the central hole 51 through which the shaft member 18 passes. It has a swash plate 50 having a contact surface portion CS that contacts the shoe that rotates with the rotation of 18, and a case 15 that supports the shaft member 18 rotatably and accommodates the swash plate 50. . When the shaft member 18 rotates within the case 15, the hydraulic oil moves outward in the radial direction by 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. This hole 60 communicates with the cylinder chamber 21 on the low-pressure side through a passage (through hole) formed in the shoe 26 and a passage formed in the piston 25 (piston through hole 25P). Accordingly, air that has moved radially inward can be sucked in from the first opening 61 of the inner wall surface portion IS, and can be sucked out from the inside of the case 15. That is, when the pump operates, air in the case 15 is automatically removed.

Although one embodiment has been described with 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, substitutions, changes, additions, and the like can be performed without departing from the gist of the embodiment.

Hereinafter, an example of the 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 portions in the above-described specific examples are used for parts that can be configured similarly to the above-described specific examples, and overlapping Description is omitted.

First, in the above-described embodiment, the flow path P provided in the swash plate 50 faces the cylinder chamber 21 on the high pressure side of the contact surface portion CS, and the cylinder chamber 21 on the high pressure side of the swash plate 50 An example in which the space between the high-pressure side chamber CA provided between the portion facing (first supported portion 53A) and the swash plate support portion 73 (first swash plate support portion 73A) is extended in a straight line is shown. 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, thereby realizing smooth and stable tilting of the swash plate 50. Made it possible. However, it is not limited to this example, and the flow path P having one end opened at a position facing the cylinder chamber 21 on the high-pressure side among the contact surface portions CS is not only on the high-pressure side chamber CA, but also on the low-pressure side of the swash plate 50. It is also possible to communicate with the low pressure chamber CB located between the portion facing the cylinder chamber 21 (the second supported portion 53B) and the swash plate support portion (the second swash plate support portion 73B). According to this modification, the tilting operation of the swash plate 50 on the swash plate support part 73 can be made more smoothly.

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 a 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. 5. The low pressure side flow path PB extends linearly and communicates with the low pressure side chamber CB. The first relay flow path PC extends in a straight line and communicates with the high pressure side flow path PA. Particularly in the illustrated example, the first relay passage PC intersects the high-pressure side passage PA. The second relay flow path PD extends in a straight line and communicates with 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 communicate with each other.

These high-pressure side flow paths PA, low-pressure side flow paths PB, the first relay flow path PC, and the 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, and stops in the middle of the swash plate 50 without penetrating the swash plate 50. The first relay flow path PC mainly extends in a direction inclined with respect to the longitudinal direction of the swash plate in the first supported portion 53A. The second relay flow path PD is formed by performing machining such as drilling from the outer surface of the second supported portion 53B, and is stopped in the middle of the swash plate 50 without penetrating the swash plate 50. The second relay flow path PD mainly extends in a direction inclined with respect to the longitudinal direction of the swash plate in the second supported portion 53B. 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 tilting axis of the swash plate 50 so as to bypass the center hole 51. Further, the end portions of the first relay flow path PC and the second relay flow path PD on the processing start side are closed by a stopper or the like. Thereby, the flow path P is opened only at the position facing the cylinder chamber 21 on the high pressure side of the contact surface portion CS, and only in the high pressure side chamber CA and the low pressure side chamber CB.

The flow path P includes the high-pressure-side flow path PA, the low-pressure-side flow path PB, the first relay flow path PC, and the second relay flow path PD extending in four straight lines, so that the flow path P is not interfered with the hole 60. It can be easily manufactured.

Further, in the example shown in Fig. 6, the high-pressure side chamber CA may be constituted by a recess formed in the supported surface 55 of the first supported part 53A, and supported by the first swash plate support part 73A. It may be composed of a concave portion formed on the surface 75, and also, a concave portion formed in the supported surface 55 of the first supported portion 53A and a concave formed in the supporting surface 75 of the first swash plate support portion 73A It may be configured by a combination of negatives. In addition, the low pressure side chamber CB may be constituted by a concave portion formed in the supported surface 55 of the second supported portion 53B, or a concave portion formed in the supporting surface 75 of the second swash plate supporting portion 73B. Alternatively, it may be configured by a combination of a concave portion formed in the supported surface 55 of the second supported portion 53B and a concave portion formed in the supporting surface 75 of the second swash plate supporting portion 73B.

In addition, in the above-described specific example, the hole 60 is opened only in the inner wall surface portion IS and the contact surface portion CS, but is not limited to this example, and the hole 60 is a discharge port provided in the case 15 ( 13) may also penetrate. According to this example, air can be removed not only from the cylinder chamber 21 on the low pressure side but also from the discharge port 13. Therefore, it is possible to perform air evacuation more efficiently and more reliably.

Further, in the above-described specific example, an example 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 was shown, but is limited to this example. However, 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, as the shaft member 18 rotates, the hydraulic oil (oil) is supplied from the cylinder chamber 21 into the hole 60. The supplied hydraulic oil is discharged to the accommodation space S of the case 15 through the first opening 61. By discharge of the pressure oil, air bubbles remaining around the shaft member 18 can be moved by stirring. Thereby, for example, air can be removed more efficiently and reliably through the discharge port 13 provided in the case 15.

Claims (7)

Shaft member,
A cylinder block held by the shaft member,
A piston disposed to be movable into the cylinder chamber of the cylinder block,
A shoe connected to the piston,
The shaft member has an inner wall surface portion defining a central hole through which the shaft member passes, and a contact surface portion contacting a shoe that rotates along with the rotation of the shaft member, and one end is opened to the inner wall surface and the other end is opened to the contact surface. A swash plate provided with a hole penetrating the cylinder chamber through a passage provided in the piston,
A swash plate pump comprising a case for rotatably supporting the shaft member and accommodating the swash plate. The method of claim 1,
The shoe has an outer contour covering the entire opening of the other end side of the hole of the swash plate. The method of claim 1,
A swash plate type pump, wherein a discharge port through the hole of the swash plate is provided in the case. The method of claim 1,
The case has a swash plate support portion for supporting the swash plate,
The hole is opened at a position of the contact surface portion facing the cylinder chamber on the low pressure side,
One end of the contact surface portion is opened at a position facing the cylinder chamber on the high pressure side, the other end of the swash plate facing the cylinder chamber on the low pressure side and a flow path opened to the chamber positioned between the swash plate support portion, the Inclined plate type pump provided on the swash plate The method of claim 1,
The hole is open only at both ends, the swash plate type pump. A construction machine comprising the swash plate type pump according to any one of claims 1 to 5. An inner wall surface portion forming a central hole through which the shaft member passes,
A swash plate for a swash plate type pump, the swash plate for a swash plate type pump comprising an annular contact surface portion located around the central hole and in contact with a shoe holding the piston, and having an opening at one end serving as the other end side of the hole opened in the inner wall surface.

Images