JP7220608B2 - Swash plate, swash plate pump and construction machinery - Google Patents

Description

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

Swash plate pumps are used in various technical fields, for example, as disclosed in Patent Document 1. Before the swash plate pump is actually used, the case is filled with hydraulic oil. At this time, the air in the case is vented using an air vent port provided in the case. This air bleeding operation is carried out every time the hydraulic oil is replaced for inspection or the like. Therefore, it is demanded to reduce the work load of removing the air from the swash plate type pump.

Japanese Utility Model Laid-Open No. 2-26772

SUMMARY OF THE INVENTION 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 removing air from a swash plate pump.

A swash plate pump according to the present invention comprises:
a shaft member;
a cylinder block held by the shaft member;
a piston movably arranged in a cylinder chamber of the cylinder block;
a shoe connected to the piston;
It has an inner wall surface portion forming a central hole through which the shaft member passes, and a contact surface portion that comes into contact with the shoe that rotates as the shaft member rotates, one end of which is open to the inner wall surface portion and the other end of which is the contact surface portion. a swash plate provided with a hole that opens to the face portion and communicates with the cylinder chamber via a passage provided in the piston;
a case that rotatably supports the shaft member and houses the swash plate.

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

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

In the swash plate pump according to the invention,
the case has a swash plate supporting portion that supports the swash plate;
the hole opens at a position facing the cylinder chamber on the low pressure side of the contact surface portion,
One end opens at a position of the contact surface portion facing the cylinder chamber on the high pressure side, and the other end is positioned 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 may be provided with a flow path opening into the chamber.

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

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

A construction machine according to the invention comprises any of the swash plate pumps according to the invention described above.

The swashplate according to the invention comprises:
an inner wall portion forming a central hole through which the shaft member passes;
an annular contact surface portion provided around the central hole and in contact with the shoe holding the piston, the one end side of which is provided with an opening serving as the other end side of the hole that is open to the inner wall surface portion.

Advantageous Effects of Invention According to the present invention, it is possible to greatly reduce the burden of removing air from a swash plate pump.

FIG. 1 is a diagram for explaining one embodiment of the present invention, and is a side view showing an example of a construction machine to which a swash plate pump can be applied. FIG. 2 is a longitudinal sectional view showing an example of a swash plate type pump 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. FIG. 4 is a perspective view showing a swash plate support portion of the swash plate type pump of FIG. 2. FIG. 5 is a plan view showing a contact surface portion of the swash plate of FIG. 3. FIG. FIG. 6 is a plan view corresponding to FIG. 5 and showing a modification of the swash plate pump.

An embodiment of the present invention will be described below with reference to the drawings. It should be noted that the elements shown in each drawing may include elements whose sizes, scales, etc. are shown different from the actual ones, in order to facilitate understanding.

The swash plate type pump 10 described below is a so-called variable displacement swash plate type piston pump. The swash plate pump 10 sucks working oil into a cylinder chamber 21 which will be described later, and discharges the working oil from the cylinder chamber 21 . More specifically, by rotating the shaft member 18 with power from a power source such as an engine, the cylinder block 20 connected to the shaft member 18 by a spline connection or the like is rotated. The piston 25 is reciprocated. Hydraulic oil is drawn into some of the cylinder chambers 21 and discharged from the other cylinder chambers 21 in accordance with the reciprocating motion of the piston 25 .

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

Hydraulic excavator 90 generally includes a lower frame 91 having crawlers, an upper frame 92 provided pivotably with respect to lower frame 91, a boom 93 attached to upper frame 92, and an arm 94 attached to boom 93. , and a bucket 95 attached to an arm 94 . Hydraulic cylinders 96A, 96B, and 96C are actuators for boom, arm, and bucket, and drive boom 93, arm 94, and bucket 95, respectively. Further, when rotating the upper frame 92 , the rotational driving force from the rotating device 97 is transmitted to the upper frame 92 . When the hydraulic excavator 90 is caused to travel, the rotational driving force from the travel device 98 is transmitted to the crawlers of the lower frame 91 . The swing device 97 and the traveling device 98 are configured by hydraulic motors that output rotation when hydraulic pressure is input. The swash plate pump 10 supplies pressure oil to hydraulic actuators such as the hydraulic cylinders 96A, 96B, 96C, the swing device 97 and the travel device 98. As shown in FIG.

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

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

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 using fasteners such as bolts. The case 15 forms an accommodation space S inside thereof. A cylinder block 20, a piston 25, a valve plate 30, a tilt adjustment mechanism 35, and a swash plate 50 are arranged in the accommodation space S.

In the illustrated example, a valve plate 30 is arranged inside the first case block 15a. A first oil passage 11 and a second oil passage 12 communicating with the cylinder chamber 21 of the cylinder block 20 via the valve plate 30 are formed in the first case block 15a. In the drawing, for convenience of explanation, the first oil passage 11 and the second oil passage 12 are represented by lines, but in actuality, they are appropriately arranged according to the supply and discharge of hydraulic oil to the cylinder chamber 21 of the cylinder block 20 . It has a large inner dimension (inner diameter). The first oil passage 11 and the second oil passage 12 are provided through the case 15 from inside the case 15 to outside the case 15 . The first oil passage 11 and the second oil passage 12 communicate with an actuator, a hydraulic pressure source, and the like provided outside the swash plate pump 10 .

The shaft member 18 is rotatably supported by the case 15 via bearings 19a and 19b. The shaft member 18 can rotate with its center 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 a bearing 19a and extends out of the case 15 through a through hole provided in the second case block 15b. A seal member is provided between the case 15 and the shaft member 18 at the portion where the shaft member 18 passes through the case 15 to prevent hydraulic oil from flowing out of the case 15 . A 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 columnar 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 spline connection, for example. The cylinder block 20 can rotate around 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. A part of the spline teeth may be exposed in the accommodation space S inside the case 15 without being covered with the cylinder block 20 . The spline teeth exposed inside the case 15 can promote the discharge of air (bubbles) remaining inside the case 15, as will be described later. In particular, it is preferable that the spline teeth exposed inside the case 15 extend into the center 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 around the rotation axis RA. Each cylinder chamber 21 opens on the swash plate 50 side in the axial direction DA parallel to the rotation axis RA. In the illustrated example, each cylinder chamber 21 extends parallel to the axial direction DA. A connection port 22 is formed corresponding to each cylinder chamber 21 . The connection port 22 opens the cylinder chamber 21 to the valve plate 30 side in the axial direction DA.

A piston 25 is provided corresponding to each cylinder chamber 21 . A portion of each piston 25 is located within 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 can move forward toward the swash plate 50 in the axial direction DA to expand the volume of the cylinder chamber 21 . Also, 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 within the case 15 . The swash plate 50 is arranged facing the cylinder block 20 and the pistons 25 in the axial direction DA. As shown in FIG. 2 , the shaft member 18 passes through a central hole 51 of the swash plate 50 . The swash plate 50 has an inner wall surface portion IS that forms (divides, defines) a central hole 51 through which the shaft member 18 passes, and a contact surface portion CS that contacts the shoe 26 that rotates as the shaft member 18 rotates. are doing. The contact surface portion CS is positioned to face the cylinder block 20 and the piston 25 . The swash plate 50 is supported within the case 15 so that the contact surface portion CS can be tilted with respect to a plane perpendicular to the rotation axis RA. A 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, which is one side end of the piston 25, is formed in a spherical shape. 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 of the swash plate 50 while contacting the contact surface portion CS.

The swash plate pump 10 further includes a retainer plate 27 located 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 . A support portion 18a of the shaft member 18 that supports the retainer plate 27 is formed into a curved surface. Therefore, 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 along the contact surface portion CS of the swash plate 50 and contacts the shoe 26 .

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 against the swash plate 50 side 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. Spring member 28a urges support member 18a against retainer plate 27 via pin 28b, thereby forcing shoe 26 toward swash plate 50. As shown in FIG.

The valve plate 30 is fixed to the first case block 15a. That is, the valve plate 30 remains stationary while the cylinder block 20 rotates with the shaft member 18 . Two or more ports (not shown) are formed in the valve plate 30 . Each port communicates with the first oil passage 11 or the second oil passage 12 . The ports are formed, for example, along an arc around the rotation axis RA, and sequentially face the connection ports 22 corresponding to the cylinder chambers 21 as the cylinder block 20 rotates. As a result, the connection between each cylinder chamber 21 and the first oil passage 11 and the second oil passage 12 can be switched according to the rotational state of the cylinder block 20 .

The operation of the swash plate pump 10 will now be described. The shaft member 18 rotates about the rotation axis RA by a rotational driving force from input means such as a motor and 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 retreats into the cylinder block 20 . The volume of the cylinder chamber 21 changes due to the advancing motion and retracting motion of the piston 25 .

While the piston 25 retreats from the position (top dead center) where it extends most out of the cylinder chamber 21 to the position (bottom dead center) where it enters the cylinder chamber 21 the most, the cylinder chamber 21 containing the piston 25 is retracted. Capacity decreases. During at least part of this period, the cylinder chamber 21 containing 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 passage on the high pressure side.

On the other hand, while the piston 25 moves forward from the bottom dead center to the top dead center, the capacity of the cylinder chamber 21 containing the piston 25 increases. During at least a part of this period, the cylinder chamber 21 containing the advancing piston 25 is connected to, for example, the second oil passage 12 via a port (not shown) of the valve plate 30 to suck working oil into the cylinder chamber 21. do. The second oil passage 12 is connected to a tank or the like that stores hydraulic oil as a low pressure side passage.

In the swash plate 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, depending on the inclination of the swash plate 50, more precisely, the inclination angle θi (see FIG. 2) of the contact surface portion CS of the swash plate 50 with respect to a plane perpendicular to the axial direction DA, the A reciprocating stroke of the piston 25 along the direction DA is determined. By changing the inclination of the swash plate 50, that is, by tilting the swash plate 50, the output of the swash plate pump 10 can be changed. Specifically, as the inclination of the swash plate 50 increases, in other words, as the inclination angle θi increases, the output of the swash plate pump 10 increases. As the inclination of the swash plate 50 decreases, in other words, as the inclination angle θi decreases, the output of the swash plate pump 10 decreases. When the contact surface portion CS of the swash plate 50 becomes perpendicular to the axial direction DA, that is, when the inclination angle θi becomes 0°, the output from the swash plate pump 10 is theoretically disabled.

Therefore, in the illustrated swash plate type pump 10, the swash plate 50 is held so as to be tiltable, that is, held so that the inclination angle θi formed by the contact surface portion CS with respect to the axial direction DA can be changed. A configuration for tiltably holding the swash plate 50 within the case 15 will be described below.

As shown in FIG. 2, the swash plate pump 10 includes a support member 70 that supports the swash plate 50 so that the inclination of the swash plate 50 can be changed, that is, the support member 70 that supports the swash plate 50 so that the swash plate 50 can be tilted. 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 passes 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 the central through hole 71 interposed therebetween. The shaft member 18 passes between the two swash plate support portions 73A and 73B and penetrates through the central through hole 71 . Each swash plate support portion 73 is formed with a receiving recess 74 that receives a later-described bulging portion 54 of the swash plate 50 . The receiving recess 74 has a shape corresponding to a portion of the side surface of the cylinder (for example, the side surface of a semi-cylinder). In the illustrated example, the support member 70 is formed separately from the case 15 and fixed to the case 15 via a fixture or the like. However, without being limited to this example, the support member 70 may be 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.

On the other hand, as shown in FIG. 2 , the swash plate 50 has a supported portion 53 arranged on the swash plate support portion 73 of the support member 70 . The supported portion 53 includes a bulging portion 54 having a complementary shape to the receiving recess 74 . The bulging portion 54 has a shape corresponding to a portion of a cylinder (for example, a semi-cylindrical shape). The swash plate 50 has a first supported portion 53A and a second supported portion 53B spaced apart 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 support portion 73A, and the second supported portion 53B is supported by the second swash plate support portion 73B.

In this example, the swashplate support portion 73 of the support member 70 has an arcuate support surface 75 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 support portion 73, the supported surface 55 of the supported portion 53 comes into contact with the support surface 75 of the swash plate support portion 73, especially surface contact on the curved surface. can. The supported portion 53 slides, that is, moves (or slides) while contacting the swash plate support portion 73 in the receiving recess 74 , so that the swash plate 50 including the supported portion 53 is It rotates with respect to the support member 70 about the center of the arc defined by the support surfaces 55 and 75 as the axis. Although not particularly limited, the axis of this tilting motion 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.

The swash plate pump 10 further includes a tilt adjustment mechanism 35 for controlling the tilt of the contact surface portion CS of the swash plate 50, as shown in FIG. In the illustrated example, the tilt adjustment mechanism 35 includes a swash plate pressing member 36 and a swash plate control device 37 . The tilt adjustment mechanism 35 will be described below.

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

The swash plate pressing member 36 and the swash plate control device 37 of the tilt adjustment mechanism 35 push the swash plate 50 to tilt in opposite directions. 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 force receiving portion 50b of the swash plate 50 and presses the swash plate 50 to tilt counterclockwise in FIG. The swash plate control device 37 comes into contact with the second force receiving portion 50c of the swash plate 50 and pushes the swash plate 50 to rotate clockwise in FIG.

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

The swashplate control 37 , on the other hand, is designed as an adjusting actuator 38 and has a control piston 39 . The control piston 39 can move toward the swash plate 50 (advance) and move away from the swash plate 50 (retreat) along the axial direction DA. The control piston 39 pushes the second force receiving portion 50 c of the swash plate 50 . The control piston 39 is driven hydraulically, for example. The force with which the control piston 39 presses the second force receiving portion 50c is adjustable. That is, the tilt 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 the inclination angle of the swash plate 50 with respect to a 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 a plane perpendicular to the axial direction DA. It is an angle (see Fig. 2).

In the illustrated example, when there is no output from the swash plate control device 37, the inclination angle θi is maximized 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 force receiving portion 50c of the swash plate 50, the swash plate 50 is raised from the maximum tilted state, and the tilt angle θi can be reduced. Further, by pushing the swash plate 50 with a greater 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 illustrated typical example, the swash plate 50 can be tilted from the maximum tilted state shown in FIG. is not intended to tilt in the opposite direction. Therefore, in the illustrated typical example, the standing state in which the tilt angle is 0° is the minimum tilt state. In such an example, when passing over a region overlapping one of the supported portions 53 (in the illustrated example, the first supported portion 53A) 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 area 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. When doing so, the pressure in the cylinder chamber 21 becomes low. In other words, one supported portion 53 (the 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 (the illustrated example Now, the second supported portion 53B) faces the low pressure side cylinder chamber 21 in the axial direction DA. The piston 25 in the high-pressure side cylinder chamber 21 moves from the top dead center to the bottom dead center, and the piston 25 in the low-pressure side cylinder chamber 21 moves from the bottom dead center to the top dead center.

Here, during operation of the swash plate pump 10 , the swash plate 50 is pushed toward the support member 70 by the pressure of the working 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 supporting portion 73A with a stronger force, and the second supported portion 53B on the low pressure side is pushed with a weaker force. 2 is pushed toward the swash plate support portion 73B. When the swash plate 50 is pushed toward the support member 70 with high pressure, the force required for the tilting operation of the swash plate 50 also increases, and 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. As shown in FIG. The chamber CA communicates with a channel P formed in the swash plate 50 . Here, the flow path P is a flow path for pressurized hydraulic oil. The chamber CA is thus filled with pressurized oil, ie pressurized hydraulic fluid. The pressure oil in the chamber C pushes the swash plate 50 away from the swash plate support portion 73 in the axial direction DA, in other words, in the direction of approaching the cylinder block 20 and the pistons 25 in the axial direction DA. Furthermore, it is possible to form an oil film between the supported surfaces 55 and 75 to avoid direct frictional contact between the swash plate supporting portion 73 and the supported portion 53 . By supplying pressure oil into the chamber CA in this manner, friction between the swash plate 50 and the swash plate support portion 73 can be reduced. As a result, the tilting of the swash plate 50 by the tilting adjustment mechanism 35 can be facilitated.

In the illustrated example, the flow path P communicates with the cylinder chamber 21 on the high pressure side. Therefore, the chamber CA is supplied with the working oil in the cylinder chamber 21 on the high pressure side. As shown in FIG. 3, one end of the flow path P opens 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 a chamber CA provided between the first supported portion 53A facing the cylinder chamber 21 on the high pressure side of the swash plate 50 and the first swash plate supporting portion 73A. The flow path P is a straight passage and can be produced by machining such as drilling. A piston through hole 25P is formed in each piston. The shoe 26 holds the periphery of the head of the piston 25 so as to expose the piston through hole 25P to the contact surface portion CS. As the shoe 26 moves on the contact surface portion CS, the piston through hole 25P faces and communicates with the opening of the flow channel P located on the contact surface portion CS. At this time, the through hole of the ring-shaped portion of the shoe 26 that holds the head of the piston 25 also functions as part of the pressure oil passage. 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. It may be configured by a recess formed in the supported surface 55 of the portion 53A.

By the way, in the swash plate type pump 10 configured as described above, the housing space S in the case 15 is filled with hydraulic oil. If the swash plate pump 10 is used with air remaining in the housing space S, problems such as noise, malfunction, and damage may occur. Therefore, before using the swash plate pump 10 after manufacture, before using it after overhauling the swash plate pump 10, or before using it after replacing the hydraulic oil, air is removed from the case 15 . This venting is conventionally accomplished through an exhaust port 13 (see FIG. 1) formed in case 15 .

On the other hand, in the present embodiment, a contrivance is made to reduce the work load of removing 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 opens to the inner wall surface portion IS, and the other end of the hole 60 opens to the contact surface portion 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. 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. As shown in FIG. Therefore, this hole 60 can communicate with the cylinder chamber 21 of the cylinder block 20 through the passage provided in the shoe 26 and the piston 25 .

Particularly in the illustrated example, the second opening 62 is located in a 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 where it enters the cylinder chamber 21 the most toward the top dead center where it projects the most from the cylinder chamber 21 . Therefore, the second opening 62 communicates with the cylinder chamber 21 that accommodates the piston 25 moving from the bottom dead center to the top dead center in the contact surface portion CS. The cylinder chamber 21 on the low pressure side has a negative pressure and usually sucks hydraulic oil through the valve plate 30 . Therefore, the hole 60 of the swash plate 50 communicates with the cylinder chamber 21 on the low-pressure side through the second opening 62, so that the air remaining in the case 15 can be sucked through the first opening 61 and discharged. .

When the shaft member 18 rotates in the case 15, the hydraulic oil, which has a higher specific gravity than air, moves outward in the radial direction due to centrifugal force. Conversely, when the shaft member 18 rotates, the air, which has a lower specific gravity than the hydraulic oil, moves radially inward. Here, the radial direction is a direction perpendicular to the central axis RA. The radially outer side is the side away from the center axis RA in the radial direction, and the radially inner side is the side closer to the center axis RA in the radial direction. Therefore, when the swash plate pump 10 starts operating and the shaft member 18 rotates, the air in the case 15 tends to gather around the shaft member 18 .

A first opening 61 of the hole 60 opens in the central hole 51 of the swash plate 50 . 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 automatically gathers around the shaft member 18, and the air around the shaft member 18 is directed to the hole 60, the through hole of the shoe 26, and the piston through hole of the piston 25. Via 25P, it can be sucked into the cylinder chamber 21 on the low pressure side. Air sucked into the cylinder chamber 21 from the housing space S is discharged out of the case 15 via the second oil passage 12, for example. That is, by starting the operation of the swash plate pump 10, the air can be automatically removed. Therefore, it is also possible to substantially eliminate the work burden of removing the air. Such a function and effect can be said to be a remarkable function and effect that a person skilled in the art cannot predict from the technical level.

In the particularly illustrated example, the holes 60 are open at both ends only. Therefore, air can be sucked into the hole 60 through 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. Thereby, air can be removed efficiently.

Also, 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 capable of covering the entire second opening 62 . For example, the radial width of the shoe 26 is greater than the radial width 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. Thereby, air can be removed efficiently.

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. By exposing 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. As a result, the movement of the hydraulic oil in the accommodation space S to the outside in the radial direction can be facilitated. Accordingly, it is possible to promote radially inward movement of the air in the accommodation space S, and to efficiently remove the air. Also, if the spline teeth exposed inside 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 allows air to be more efficiently sucked from the first opening 61 opened in the central hole 51 .

However, the movement of the air radially inward is not limited to the exposed spline teeth, and can also be realized by a convex portion or the like 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, and can be realized by linear protrusions or the like provided on the rotating shaft member 18 and extending in the axial direction DA. .

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

According to the embodiment described above, the swash plate pump 10 includes a shaft member 18 , a cylinder block 20 held by the shaft member 18 , and a piston movably arranged in a cylinder chamber 21 of the cylinder block 20 . 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 as the shaft member 18 rotates. 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 within the case 15, the hydraulic fluid moves radially outward due to centrifugal force, and the air, which has a lower specific gravity than the hydraulic fluid, moves radially inward. On the other hand, the swash plate 50 is provided with a hole 60 opening to the inner wall surface portion IS and the contact surface portion CS. This hole 60 communicates with the low pressure side cylinder chamber 21 via a passage (through hole) formed in the shoe 26 and a passage (piston through hole 25P) formed in the piston 25 . Therefore, the air that has moved radially inward 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 removed.

Although an embodiment has been described through several specific examples, these specific examples are not intended to limit an embodiment. The above-described embodiment can be implemented in various other specific examples, and various omissions, replacements, changes, additions, etc. can be made without departing from the spirit of the embodiment.

An example of modification will be described below with reference to the drawings. In the following description and the drawings used in the following description, the same reference numerals as those used for the corresponding portions in the above-described specific example are used for the portions that can be configured in the same manner as in the above-described specific example, and redundant description is given. 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 of linearly extending between the portion (first supported portion 53A) and the high-pressure side chamber CA provided between the swash plate support portion 73 (first swash plate support portion 73A) is shown. In this example, by supplying the pressurized oil in the high pressure side cylinder chamber 21 to the high pressure side chamber CA, friction between the swash plate 50 and the swash plate support portion 73 is reduced, and the swash plate 50 is smoothly and stably tilted. I made it possible to realize the rotation. However, the present invention 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 of the contact surface portion CS may be used not only in the high pressure side chamber CA but also in the low pressure side of the swash plate 50 . It may also communicate with the low-pressure chamber CB located between the portion facing the side cylinder chamber 21 (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 passage 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 channel PA can be the same as the channel P in the example shown in FIG. 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 linearly and communicates with the high-pressure side flow path PA. Particularly in the illustrated example, the first relay channel PC intersects the high pressure side channel PA. The second relay flow path PD extends linearly and communicates with the low-pressure side flow path PB. Particularly in the illustrated example, the second relay flow path PC intersects the low-pressure side flow path PB. Also, the first relay flow path PC and the second relay flow path PC communicate 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, for example. In the illustrated example, the high pressure side passage PA passes through the swash plate 50 . The low pressure side flow path PB is formed by performing machining such as drilling from the supported portion 53 side, 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. As shown in FIG. 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. As shown in FIG. 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 their ends. The first relay flow path PC and the second relay flow path PD extend obliquely with respect to the tilt axis of the swash plate 50 so as to bypass the central hole 51 . In addition, the ends of the first relay flow path PC and the second relay flow path PD, which are on the processing start side, are closed by plugs or the like. As a result, the flow path P is opened only at a position facing the cylinder chamber 21 on the high-pressure side of the contact surface portion CS, and at the high-pressure side chamber CA and the low-pressure side chamber CB.

Since the flow path P includes such four linearly extending high-pressure side flow path PA, low-pressure side flow path PB, first relay flow path PC, and second relay flow path PD, interference with the hole 60 is prevented. Therefore, the flow path P can be easily produced.

In the example shown in FIG. 6, the high-pressure side chamber CA may be configured by a concave portion formed in the supported surface 55 of the first supported portion 53A, or may be formed by a concave portion of the first swash plate support portion 73A. It may be configured by a recess formed in the support surface 75, and furthermore, 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 of Further, the low-pressure side chamber CB may be configured by a concave portion formed in the supported surface 55 of the second supported portion 53B, or may be formed by a concave portion formed in the supporting surface 75 of the second swash plate supporting portion 73B. Further, it may be configured by a combination of a recess formed in the supported surface 55 of the second supported portion 53B and a recess formed in the support surface 75 of the second swash plate support portion 73B. good.

Further, in the specific example described above, the hole 60 opens only to the inner wall surface portion IS and the contact surface portion CS, but the hole 60 is not limited to this example and also communicates with the discharge port 13 provided in the case 15. may According to such an 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, air venting can be performed more efficiently and more reliably.

Furthermore, in the specific example described above, 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 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 housing space S of the case 15 through the first opening 61 . By discharging the pressurized oil, the air bubbles remaining around the shaft member 18 can be stirred and moved. As a result, the air can be removed more efficiently and more reliably via the discharge port 13 provided in the case 15, for example.

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 First opening 62 Second opening 73 Swash plate support Part CM Construction machine IS Inner wall portion CS Contact surface portion P Channel CA High-pressure side chamber

Claims (7)

a shaft member;
a cylinder block held by the shaft member;
a piston movably arranged in a cylinder chamber of the cylinder block;
a shoe connected to the piston;
It has an inner wall surface portion forming a central hole through which the shaft member passes, and a contact surface portion that comes into contact with the shoe that rotates as the shaft member rotates, one end of which is open to the inner wall surface portion and the other end of which is the contact surface portion. a swash plate provided with a hole opening to the face portion and communicating with the cylinder chamber via a passage provided in the piston;
and a case that rotatably supports the shaft member and houses the swash plate. 2. A swash plate pump according to claim 1, wherein said shoe has an outer contour covering the entire opening of said hole of said swash plate on said other end side. 3. A swash plate pump according to claim 1, wherein said case is provided with a discharge port communicating with said hole of said swash plate. the case has a swash plate supporting portion that supports the swash plate;
the hole opens at a position facing the cylinder chamber on the low pressure side of the contact surface portion,
One end opens at a position of the contact surface portion facing the cylinder chamber on the high pressure side, and the other end is positioned between the portion of the swash plate facing the cylinder chamber on the low pressure side and the swash plate support portion. 4. The swash plate pump according to any one of claims 1 to 3, wherein the swash plate is provided with a flow path that opens into a chamber for pumping. A swash plate pump according to any one of claims 1 to 4, wherein said holes are open only at both ends. A construction machine comprising the swash plate pump according to any one of claims 1 to 5. an inner wall portion forming a central hole through which the shaft member passes;
a swash plate type pump provided with an annular contact surface portion positioned around the central hole and in contact with the shoe holding the piston, the one end side of which is provided with an opening serving as the other end side of the hole opened to the inner wall portion. Swashplate for

Images