Swashplate type axial piston pump motor

Abstract

To provide a swash plate type axial piston pump motor in which a valve plate in slide contact with a cylinder block can be easily placed at a pump main body coaxial therewith.SOLUTION: A plurality of pistons 17 is arranged at a cylinder block 15 which is accommodated in a main body 1, and engaged with a rotating shaft 7 in a rotation direction so as to be freely reciprocal in an axial direction. A tip part of each of the pistons 17 comes in slide contact with a swash plate 14 to set a reciprocation amount of the piston 17. There is provided a valve plate 28 in which suction / discharge ports 29 and 30 for allowing the circulation of fluids while being in slide contact with the cylinder block 15 are formed. The main body 1 constitutes lid members 3 and 4 by spigot-joining them into an accommodation hole 5 of a housing 2 which accommodates the cylinder block 15 therein. The rotating shaft 7 is rotatably pivoted to the lid members 3 and 4 .The valve plate 28 is placed at the main body 1 coaxial with the rotating shaft 7 by spigot-joining an external periphery to the accommodation hole 5 which spigot-joins the lid member 4 thereto.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a swash plate type axial piston pump / motor in which a plurality of pistons are arranged reciprocally slidable in the axial direction in a cylinder block, the reciprocating momentum of the pistons is set by a swash plate, and fluid is inhaled and discharged through suction and discharge ports formed in a disk-shaped valve plate that slidably contacts the cylinder block.

Background Art

[0002] This type of swash plate type axial piston pump / motor forms a main body (pump main body) by closing both ends of a housing with lid members (flange members). A cylinder block is engaged with a rotating shaft (drive shaft) that is rotatably supported by the main body. A plurality of pistons are arranged reciprocally slidable in the axial direction and equidistantly in the circumferential direction in the cylinder block. Shoes pivotally attached to the piston tips slidably contact a disk-shaped swash plate fixed to the main body to set the reciprocating momentum of the pistons. Suction and discharge ports for fluid flow are formed in a disk-shaped valve plate that slidably contacts the cylinder block, and the valve plate is fixed to the lid member concentrically with the rotating shaft and the cylinder block. In operation, in pump operation, the cylinder block is rotationally driven by the rotating shaft, causing the pistons to reciprocate and resulting in the suction and discharge of fluid. In motor operation, the pistons reciprocate due to the acting force based on the pressure of the supplied fluid, causing the rotating shaft to rotate together with the cylinder block.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in conventional swashplate type axial piston pump motors, the disc-shaped valve plate is fixed to the main body's cover member with two radially opposing pin members, and is positioned concentrically with the rotating shaft and cylinder block. This requires the two pin members to be highly precise, which poses a problem in terms of manufacturing complexity.

[0005] The object of the present invention is to provide a swashplate type axial piston pump motor in which a valve plate that slides against the cylinder block is easily positioned on the pump body concentrically with the axis of rotation. [Means for solving the problem]

[0006] The main body comprises a cylinder block housed within the main body and engaged with the rotating shaft in the rotational direction, a plurality of pistons arranged in the cylinder block so as to be able to reciprocate in the axial direction, a plurality of working chambers partitioned by each piston and the cylinder block for drawing in and discharging fluid, a swash plate that the tips of each piston protruding from the cylinder block slide against to set the reciprocating motion of each piston, and a valve plate that slides against the cylinder block and forms intake and exhaust ports through which the fluid drawn in and discharged to each working chamber flows. The main body is constructed by fitting a lid member into a housing hole in which the cylinder block is housed, the rotating shaft is rotatably supported on the lid member, the valve plate is fitted on its outer circumference into the housing hole into which the lid member is fitted, and is positioned in the main body concentrically with the rotating shaft and in contact with the lid member, and a drain hole is formed in the valve plate axially through which the drain that leaks between it and the contacting lid member flows and flows out into the housing hole. The drain holes do not communicate with each working chamber. This is a swashplate type axial piston pump motor characterized by the following features.

[0007] In this case, the valve plate may be prevented from rotating by engaging its engaging portion with the main body. [Effects of the Invention]

[0008] As described in detail above, the invention described in claim 1 is constructed such that the main body is fitted with a lid member in a housing hole that houses a cylinder block inside, the rotating shaft is rotatably supported on the lid member, the valve plate is fitted with its outer circumference in a lid-fit to the housing hole into which the lid member is fitted, and is positioned on the main body concentrically with the rotating shaft and in contact with the lid member, and the valve plate has a drain hole formed axially through which the drain that has leaked between it and the contacting lid member flows and flows out into the housing hole. The drain holes do not communicate with each working chamber. Therefore, since the mounting hole into which the valve plate is fitted is the same as the lid member that is fitted in a spigot, there is no need to prepare a special member to position the valve plate concentrically with the axis of rotation, and the valve plate can be easily positioned concentrically with the axis of rotation on the main body.

[0009] Furthermore, in the invention described in claim 2, the valve plate is prevented from rotating by engaging its engaging portion with the main body. Therefore, the valve plate can be reliably prevented from rotating with the main body. [Brief explanation of the drawing]

[0010] [Figure 1] This is a longitudinal cross-sectional view of a swashplate type axial piston pump motor showing one embodiment of the present invention. [Figure 2] This is a cross-sectional view along line AA in Figure 1. [Figure 3] This is a cross-sectional view corresponding to Figure 2, which shows another embodiment. [Modes for carrying out the invention]

[0011] The following describes one embodiment of the present invention in which a swashplate type axial piston pump motor is used as a swashplate type axial piston pump, based on the drawings. In Figures 1 and 2, 1 is the main body, which consists of a cylindrical housing 2, a front cover member 3, and a rear cover member 4. The front cover member 3 closes one end opening of the storage hole 5, which is formed to penetrate the housing 2 axially, and the rear cover member 4 closes the other end opening of the storage hole 5. The two cover members 3 and 4, which sandwich the housing 2, are fastened together with a plurality of bolt members 6. The two cover members 3 and 4 are concentrically fitted into the openings at both ends of the storage hole 5. 7 is the rotating shaft, and the storage hole 5The shaft is inserted through the interior and rotatably supported by a radial ball bearing 8 located on the front cover member 3 and a radial roller bearing 9 located on the rear cover member 4. Its tip protrudes outside the front cover member 3 and is connected to an electric motor (not shown). The radial ball bearing 8 is exposed to the outside. The radial roller bearing 9 is located in a bottomed hole 10 drilled in the rear cover member 4 and is not exposed to the outside.

[0012] The front cover member 3 has a retaining member that is positioned axially inward of the radial ball bearing 8. 11 Sealing member via 12 The front cover member 3 has an inclined surface on its inner end face facing the inside of the main body 1, and a disc-shaped swash plate 14 is fixed to it. The rotating shaft 7 is loosely fitted to the axis of the swash plate 14. The swash plate 14 is inclined at a certain angle with respect to a line perpendicular to the axis of the rotating shaft 7. 15 is a cylinder block, which is housed in a housing hole 5 of the housing 2 that constitutes the main body 1, and engages with the rotating shaft 7 in the rotational direction by spline engagement at its own axis, and is rotationally driven by the rotating shaft 7.

[0013] The cylinder block 15 has a plurality of piston holes 16 formed radially outward from the axis and at equal intervals in the circumferential direction. Each piston hole 16 opens to one end face of the cylinder block 15 facing the swash plate 14. 17 is a piston, which is fitted into each piston hole 16 of the cylinder block 15 so as to be able to reciprocate in the axial direction, and divides the cylinder block 15 into an operating chamber 18. Each piston 17 has a passage hole 19 that penetrates axially through the axis, and the tip facing the swash plate 14 is formed into a spherical protrusion to pivotally attach the shoe 20.

[0014] The shoe 20 has a through hole 21 formed axially through its axis, communicating with the flow hole 19 of the piston 17, and is equipped with a sliding contact member 22 at its tip that slides against the swash plate 14. The sliding contact member 22 is formed in an annular shape from a resin material and is press-fitted onto the shoe 20. The swash plate 14 sets the reciprocating motion of each piston 17 based on its inclined angle. Each shoe 20 is pressed against the swash plate 14 by the spring force of a spring 23 housed in the axis of the cylinder block 15, via a pin 24, retainer 25, and retainer plate 26. The working chamber 18 increases in volume as each piston 17 moves forward in the right direction in Figure 1, drawing in fluid, and decreases in volume as each piston 17 moves backward in the left direction in Figure 1, discharging fluid. Each working chamber 18 is connected to a connecting hole 27, which opens at equal intervals in the circumferential direction on the other end face of the cylinder block 15 opposite one end face.

[0015] 28 is a disc-shaped valve plate that slides against the other end face of the cylinder block 15, and has a pair of intake and exhaust ports 29 and 30 through which fluids are drawn in and discharged from each working chamber 18 via connection holes 27. Both intake and exhaust ports 29 and 30 are semi-circular in shape and are positioned symmetrically with respect to the axis of the valve plate 28. The valve plate 28 is fitted with its outer circumference into a housing hole 5 that fits the rear cover member 4 in an spigot fitting, and is positioned on the main body 1 concentrically with the rotating shaft 7. The spring force of the spring 23 is applied to the valve plate 28 via the cylinder block 15, and it is pressed against the rear cover member 4. 31 is an oval-shaped engagement hole that serves as an engagement part, and is formed to penetrate the valve plate 28 radially outward from the axis in the axial direction. 32 is a cylindrical pin member that protrudes axially from the inner surface of the rear cover member 4 and engages with the engagement hole 31. The valve plate 28 is prevented from rotating by the engagement of the pin member 32 with the engagement hole 31. Furthermore, the engagement hole 31 is designed so that the pin member 32 engages snugly with the shorter diameter portion, while the longer diameter portion is extended radially to be larger than the pin member 32, thereby facilitating the engagement of the pin member 32 and preventing the valve plate 28 from rotating.

[0016] 33 is a drain hole, and three drain holes are formed axially through the valve plate 28 at equal intervals in the circumferential direction on the same circumference as the engaging hole 31. Each drain hole 33 allows the drain leaked between the valve plate 28 and the rear cover member 4 to flow through and flow out into the housing hole 5. One of the suction / discharge ports 29 communicates with the working chamber 18 whose volume decreases during the forward movement of the piston 17, and functions as a discharge port through which the fluid discharged from the working chamber 18 flows. The other suction / discharge port 30 communicates with the working chamber 18 whose volume increases during the return movement of the piston 16, and functions as a suction port through which the fluid sucked into the working chamber 18 flows. 34 and 35 are a pair of suction / discharge flow paths formed in the rear cover member 4. One of the suction / discharge flow paths 34 is connected to one of the suction / discharge ports 29 that functions as a discharge port, and the other suction / discharge flow path 35 is connected to the other suction / discharge port 30 that functions as a suction port.

[0017] Next, the operation of such a configuration will be described. In the state of FIG. 1, when the rotary shaft 7 is rotationally driven, the cylinder block 15 rotates together with the rotary shaft 7. As the cylinder block 15 rotates, each piston 17 reciprocates with a reciprocating motion amount corresponding to the inclination angle of the swash plate 14 by the tip shoe 20 slidingly contacting along the swash plate 14, increasing or decreasing the volume of each working chamber 18.

[0018] In the working chamber 18 whose volume increases due to the rotation of the cylinder block 15, the fluid is sucked in through the suction / discharge port 30 from the suction / discharge flow path 35. Also, the fluid in the working chamber 18 whose volume decreases due to the rotation of the cylinder block 15 is discharged from the suction / discharge flow path 34 through the suction / discharge port 29. In this way, a pumping operation is performed in which the suction and discharge of the fluid are continuously carried out as the cylinder block 15 rotates. Then, when the rotational drive of the rotary shaft 7 is stopped, the pumping operation is stopped.

[0019] In such an operation, the main body 1 is formed by inlay-fitting both lid members 3 and 4 into the fitting hole 5 of the housing 2 that houses the cylinder block 15 inside. The rotating shaft 7 is pivotally supported on both lid members 3 and 4 so as to be rotatable, and the valve plate 28 is inlay-fitted with its outer periphery into the fitting hole 5 into which the rear lid member 4 is inlay-fitted and is arranged concentrically with the rotating shaft 7 in the main body 1. Therefore, since the fitting hole 5 for inlay-fitting the valve plate 28 is for inlay-fitting the rear lid member 4, there is no need to specially prepare a member for arranging the valve plate 28 concentrically with the rotating shaft 7, and the valve plate 28 can be easily arranged concentrically with the rotating shaft 7 in the main body 1.

[0020] Also, the valve plate 28 is engaged with a pin member 32 protruding from the rear lid member 4 of the main body 1 through an engagement hole 31 to prevent rotation. Therefore, the valve plate 28 can be reliably prevented from rotating in the main body 1.

[0021] FIG. 3 shows another embodiment of the present invention. The same reference numerals are given to the same parts as in one embodiment and the description thereof is omitted, and only the different parts will be described. The valve plate 36 has a part of its outer periphery cut out to form a linear engagement portion 37. The housing 38 constituting the main body 1 has a part of the fitting hole 39 formed linearly to provide a linear portion 40. When the outer periphery of the valve plate 36 is inlay-fitted into the fitting hole 39, the engagement portion 37 is engaged with the linear portion 40 to prevent rotation.

[0022] The operation is a pump operation in which each piston 17 reciprocates by the rotational drive of the rotating shaft 7 to inhale and discharge fluid. When the rotational drive of the rotating shaft 7 is stopped, the pump operation is stopped. In this operation, the valve plate 36 is inlay-fitted with its outer periphery into the fitting hole 39 into which the rear lid member 4 is inlay-fitted and is arranged concentrically with the rotating shaft 7 in the main body 1. Therefore, since the fitting hole 39 for inlay-fitting the valve plate 36 is for inlay-fitting the rear lid member 4, there is no need to specially prepare a member for arranging the valve plate 36 concentrically with the rotating shaft 7, and the valve plate 36 can be easily arranged concentrically with the rotating shaft 7 in the main body 1.

[0023] Furthermore, the valve plate 36 is prevented from rotating by engaging its engaging portion 37 with the straight portion 40 of the housing 38 of the main body 1. This ensures that the valve plate 28 is securely prevented from rotating against the main body 1.

[0024] In the above-described embodiment, the swashplate type axial piston pump-motor was described as a swashplate type axial piston pump, but it may also be described as a swashplate type axial piston motor. In this case, the cylinder block 15 is rotationally driven by a fluid supplied from an external source, and the cylinder block 15 rotates the rotating shaft 7. Furthermore, although a constant-capacity type was described with a fixed inclination angle of the swashplate 14, it is of course possible to use a variable-capacity type in which the inclination angle of the swashplate can be changed. [Explanation of symbols]

[0025] 1: Main unit 2, 38: Housing 3: Front cover member (cover member) 4: Rear lid member (lid member) 5, 39: Storage hole 7: Rotation axis 14: Swash plate 15: Cylinder block 17: Piston 18: Working Room 28, 36: Valve plate 29, 30: Intake and exhaust ports 31: Engagement hole (engagement part) 37: Engaging part

Claims

1. The axial piston pump / motor comprises a cylinder block housed inside the main body and engaged with the rotating shaft in the rotational direction, a plurality of pistons arranged on the cylinder block so as to be able to reciprocate in the axial direction, a plurality of working chambers partitioned by each piston and the cylinder block for drawing in and discharging fluid, a swash plate that sets the amount of reciprocating motion of each piston by sliding contact with the tips of each piston protruding from the cylinder block, and a valve plate that slides against the cylinder block and forms intake and exhaust ports through which fluid is drawn in and discharged to each working chamber, wherein the main body is constructed by fitting a cover member into a housing hole in which the cylinder block is housed inside, the rotating shaft is rotatably supported on the cover member, the valve plate is positioned on the main body by fitting its outer circumference into the housing hole into which the cover member is fitted in an spigot, concentric with the rotating shaft and in contact with the cover member, and the valve plate has a drain hole formed axially through which drain that has leaked between it and the contacting cover member flows and flows out into the housing hole, the drain hole does not communicate with each working chamber.

2. The swashplate type axial piston pump motor according to claim 1, characterized in that the valve plate is prevented from rotating by engaging its engaging portion with the main body.

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