JPH08210244A - Cylindr oil bleeding structure of hydraulic piston pump motor - Google Patents

Abstract

PURPOSE: To surely prevent leakage of oil and to simply achieve machining by a method wherein a groove extending in an axial direction is formed in a spline fit-in part between a cylinder block and a rotary shaft throughout the whole length of a fit-in part. CONSTITUTION: In a fit-in hole 41 formed in the central part of a cylinder block 40, a spline groove 41a is formed in a part of the inner peripheral surface thereof and five grooves 45 extending in an axial direction are engraved at equal intervals in a peripheral direction more deeply than the spline groove 41a. A motor output shaft 31 has a protrusion fitted in the spline groove 41a of the cylinder block 40 and in a spline fit-in state, a communication hole extending along a motor output shaft 31 consists of the groove 45 axially formed in the inner peripheral surface of the fit-in hole 41. When oil leaking in the direction of a center flows to a motor output shaft 31, the five grooves 45 formed in a fit-in part between the motor output shaft 31 and the cylinder block 40 leads leakage oil to the protrusion side of a piston 50 to recover the leakage oil in a casing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic piston pump / motor such as a hydraulic piston and a hydraulic motor, and more particularly to a cylinder oil draining structure thereof.

[0002]

2. Description of the Related Art A hydraulic piston pump / motor is generally used by being incorporated in a fluid transmission device as a variable displacement hydraulic pump and a constant displacement hydraulic motor, and the hydraulic motor has a structure for removing cylinder oil. A conventional example (Japanese Utility Model Publication No. 3-30625) is shown in FIG. Common casing 03 for hydraulic pump and hydraulic motor 01
Each of them is an axial type in which the pistons are arranged parallel to the shaft, and the hydraulic pump is omitted in FIG.

The motor output shaft 04 is fitted in the casing 03, and an oil seal 010 is interposed between the motor output shaft 04 and the casing side wall 03a so as to be rotatably supported.
A cylinder block 05 is fitted in the casing 03. In the cylinder block 05, a plurality of cylinders 06 are formed around the rotation center axis, and the head of the piston 07 slidably fitted in each cylinder 06 contacts the swash plate 08 provided in the casing 03. It is held down.

The side wall 03a of the casing 03 is in sliding contact with the bottom wall 06a having the port 06b of the cylinder 06 formed therein.
A hydraulic passage is formed in 03a and port 06 of cylinder 06
It has a passage opening communicating with b at a predetermined timing. An annular bearing plate is provided in an annular recess formed in the outer peripheral edge of the sliding contact surface of the bottom wall 06a of the cylinder 06 with the side wall 03a.
09 is welded, and the surface of the bearing plate 09 is flush with the surface of the bottom wall 06a. A plurality of concave grooves are radially formed on the surface of the bearing plate 09.

The hydraulic motor 01 has a structure as described above, and pressure oil sent from a hydraulic pump (not shown) through a hydraulic passage in the casing side wall 03a is transferred to a cylinder 06 at a predetermined position via a port 06b. The cylinder block 05 is rotated by projecting the piston 07 of the cylinder 06 and pressing it against the swash plate 08, and conversely, the oil released from the cylinder 06 by the piston 07 pushed into the cylinder 06 by the swash plate 08 Returned to hydraulic pump.

[0006]

In this way, the hydraulic motor 01 rotates the cylinder block 05 together with the motor output shaft 04, but if an excessive load is applied to the motor output shaft 04, the port 06b will be generated.
The pressure of the oil that tries to flow into the cylinder 06 through the cylinder 06 increases and the bottom wall 06a of the cylinder 06 and the side wall 03 of the casing.
Oil tends to leak from the sliding contact surface with a and the sliding contact surface with the side wall 03a along the outer peripheral surface of the output motor shaft 04.

The oil leaking from the port 06b in the outer peripheral direction is pushed up the cylinder block 05 and is recovered in the casing 03 through the bearing plate 09, while the oil that permeates between the output motor shaft 04 and the side wall 03a. Therefore, large pressure may be applied to the oil seal 010 and the oil may ooze out to the outside.

Therefore, as another conventional example, there is an example in which an oil drain passage for guiding the oil leaked from the sliding contact surface between the bottom wall 06a of the cylinder 06 and the casing side wall 03a into the casing 03 is formed in the casing side wall. However, the oil drain passage must be formed on the side wall of the casing, and the working operation is not easy.

The present invention has been made in view of the above points.
The purpose is to provide a cylinder oil drain structure for a hydraulic piston pump / motor that can surely prevent oil leakage, can be machined easily, and can be manufactured at low cost.

[0010]

In order to achieve the above object, the present invention is characterized in that a cylinder block having a plurality of cylinders for accommodating pistons is spline-fitted to a rotary shaft to form a cylinder block. A casing enclosing a cylinder block rotatably supports the rotary shaft, the head of the piston is brought into contact with a swash plate provided in the casing, and a cylinder bottom wall having a port is slid on a casing side wall. In the contacted hydraulic piston pump / motor, a cylinder oil drain structure of the hydraulic piston pump / motor in which a groove oriented in the axial direction is formed in the spline fitting portion between the cylinder block and the rotary shaft over the entire fitting portion length. And

When an excessive load is applied to the rotary shaft, the oil leaked to the sliding contact surface between the cylinder bottom wall and the casing side wall is guided to the groove formed in the spline fitting portion and is collected in the casing. Therefore, there is no possibility of leakage to the outside and a drop in hydraulic pressure. It is possible to prevent the cylinder oil from leaking to the outside by a simple process of forming a groove in either the spline fitting portion of the cylinder block or the spline fitting portion of the rotary shaft, and it is possible to reduce the cost.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention shown in FIGS. 1 to 7 will be described below. This embodiment is applied to a fluid transmission device, FIG. 1 is an overall plan view of the fluid transmission device 1, FIG. 2 is a side view of the same (viewed in the direction of arrow II in FIG. 1), and FIG. And a sectional view taken along line III-III in FIG. 2, and FIG.
FIG. 4 is a sectional view taken along line IV-IV in FIG. 2.

The fluid transmission device 1 has a structure in which a variable displacement hydraulic pump 2 and a constant displacement hydraulic motor 3 are incorporated in a common casing 4 and casing side walls 5 and 6. As shown in the sectional view of FIG. 3, the hydraulic pump 2 has a pump input shaft 11 vertically inserted from the upper surface of the casing 4 and an end portion rotatably supported by the casing side wall 5. Block 12
Is fitted to the pump input shaft 11 and is rotated integrally.

The cylinder block 12 has five cylinders 13 formed around the center axis of rotation. A piston 14 is slidably fitted in each cylinder 13 to form a bottom wall of the cylinder 13.
A port 13b is formed in 13a, and the outer surface of the bottom wall 13a is in sliding contact with the casing side wall 5. The heads of pistons 14 protruding from the five cylinders 13 abut on an annular swash plate 17 positioned around the pump input shaft 11, respectively.
Constitutes a thrust bearing.

Pump input shaft penetrating the casing side wall 6
A control bar 18 inserted in a direction orthogonal to 11 has an end rotatably supported by the casing 4, and a swash plate 17 is fixed to an inner peripheral edge of a hole 18a formed in a bent portion of the control bar 18. The pump input shaft 11 passes through the hole 18a and the annular swash plate 17.

A control lever 19 is fitted to the end of the control bar 18 exposed from the casing 6,
By swinging the control lever 19, the control bar 18 rotates to change the inclination angle of the swash plate 17 fixed to the bent portion. Thus, by changing the inclination angle of the swash plate 17, the stroke length of the piston 14 is changed. Can be adjusted to control hydraulic pressure and the like.

An oil passage 5a is formed in the casing side wall 5, and the discharge port and the suction port are aligned with the port 13b of the cylinder 13 at a predetermined rotation angle so that the inside of the cylinder 13 and the oil passage 5 are in contact with each other.
Oil in and out of the cylinder 13 flows in and out of the cylinder 13, and the oil passage 5a in the casing side wall 5 communicates with the oil passage 6a in the casing side wall 6 via the joint member 20.

On the other hand, the hydraulic motor 3 has a motor output shaft 31
Is rotatably supported by passing horizontally through the casing 4 and the casing side wall 6 as shown in the cross-sectional view in FIG. 4 in a horizontal direction orthogonal to the pump input shaft 11, and a protruding port of the motor output shaft 31 of the casing 4. Is sealed by the seal member 32,
A protrusion port of the motor output shaft 31 of the casing side wall 6 is sealed by a seal member 33.

Inside the casing 4, a cylinder block 40 is spline-fitted to the motor output shaft 31. The cylinder block 40 is made of sintered alloy and is shown in FIG.
As shown in FIG. 7, it has a columnar shape with a fitting hole 41 through which the motor output shaft 31 penetrates and is fitted in the center, and five cylinders 42 are axially oriented at equal intervals. Has been formed.

An arc-shaped port 44 is formed for each cylinder 42 on a bottom wall 43 that opens one side and closes the other side, and an annular port 44 is formed on the surface of the bottom wall 43 further outside the port 44. Grooves 43a are engraved, and a plurality of grooves 43b are formed up to the outer peripheral surface in the radial direction on a bearing plate integrally provided on the outer periphery of the groove 43a.

A fitting hole at the center of the cylinder block 40
In 41, a spline groove 41a is formed in a part of the inner peripheral surface thereof, and five grooves 45 oriented in the axial direction at equal intervals in the circumferential direction are formed deeper than the spline groove 41a. Since the cylinder block 40 is formed by sintering, no machining is required to form the groove 45, and the cylinder block 40 is easy to manufacture and low in cost.

One of the motor output shafts 31 is formed with a ridge that fits into the spline groove 41a of the cylinder block 40. When fitted into the fitting hole 41 of the cylinder block 40 and fitted with a spline, relative rotation is prohibited. Then, the shaft 45 integrally rotates, and in the spline fitting state, the groove 45 formed in the inner peripheral surface of the fitting hole 41 in the axial direction forms a communication hole along the motor output shaft 31.

A piston 50 is slidably fitted into each of the five cylinders 42 of the cylinder block 40, and a swash plate 51 presses the head of the piston 50. Swash plate 51
Is composed of an annular thrust bearing, is penetrated by the motor output shaft 31, and is fixed inside the casing 4 at a predetermined inclination angle with respect to the axial direction. The casing side wall 6, which is in sliding contact with the outer surface of the bottom wall 43 of the cylinder block 40, has an oil passage 6a formed therein, which communicates with the joint 20.
The oil passage 6a has an inflow port and an outflow port which communicate with the arc-shaped port 44 of the cylinder 42 at a predetermined rotation angle.
Oil communicates with the inside of 42 to allow oil to flow in and out.

A circular hole 4a is provided in the upper part of the casing 4, and concentric circular projections 4b and 4c are formed around the circular hole 4a on the casing surface to form an annular groove therebetween. An outer peripheral edge portion 55a of a rubber bellows type breather member 55 is fitted in the groove to close the circular hole 4a, and a cap 56 covers the breather member 55 to cover the cap.
The outer peripheral edge portion 55a of the breather member 55 fitted in the groove at the flange portion 56a of 56 is fixed by a pressing bolt 57. The breather member 55 has a bent portion 55b that is formed in an annular shape and bulges upward at the inner peripheral portion of the outer peripheral edge portion 55a, and has several pinholes formed in the bent portion 55b.

The fluid transmission device 1 has a structure as described above, the casing 4, the casing side walls 5 and 6 are filled with oil, and the power input to the pump input shaft 11 of the hydraulic pump 2 is used. Is a cylinder block
Cylinder block 40 is driven by rotating piston 14 and being controlled by swash plate 17 so that piston 14 discharges and sucks oil and sends hydraulic pressure to cylinder 42 on hydraulic pump 3 side to drive piston 50.
With the pump output shaft 31. By operating the control lever 19 to change the inclination angle of the swash plate 17 on the hydraulic pump 2 side, the flow rate can be adjusted and the power transmission characteristic can be changed.

If the oil leaks from the inside of the casing to the outside or the air is filled inside, the necessary hydraulic pressure cannot be obtained and the use becomes useless. Therefore, the casing is liquid-tight and the breather device is installed. It is provided. However, when an excessive load is applied to the motor output shaft 31, for example, from the port 44 of the cylinder 42 of the cylinder block 40 to the bottom wall 43.
Oil may leak to the sliding contact surface of the casing 6.

When the oil leaking toward the center reaches the motor output shaft 31, the motor output shaft 31 and the cylinder block
The five grooves 45 formed in the fitting portion with 40 guide the leaked oil to the protruding side of the piston 50 and collect it in the casing. Therefore, lifting of the cylinder block 40 at high pressure is suppressed and the performance is improved. Stabilization can be achieved. In this way, since the groove 45 positively escapes the leaked oil and collects it in the casing, the oil is transmitted through the sliding contact surface between the casing 6 and the motor output shaft 31, and the seal member 33 is pushed out to the outside. Can be prevented.

The bottom wall 43 of the cylinder 42 and the casing 6
When the oil leaking to the sliding contact surface of the oil leaks in the centrifugal direction, it is collected in the casing through the grooves 43a and 43b provided on the surface of the bottom wall 43, and there is no problem. The number of parts is small because there is no separate member.

In the above embodiment, the groove 45 is formed on the cylinder block 40 side at the fitting portion between the motor output shaft 31 and the cylinder block 40, but conversely, the groove is formed at the fitting portion on the motor output shaft 31 side. The groove may be formed easily.

[0030]

According to the present invention, when an excessive load is applied to the rotary shaft, oil leaked to the sliding contact surface between the cylinder bottom wall and the casing side wall is guided to the groove formed in the spline fitting portion. Since it is collected inside the casing, the cylinder block will not be pushed up excessively, and oil will not leak through the seal to the outside to cause a decrease in hydraulic pressure. It is possible to prevent leakage of cylinder oil to the outside with a simple process to form a groove in either the spline fitting part of the cylinder block or the spline fitting part of the rotary shaft, and it is possible to reduce the cost. There is no sudden drop in hydraulic pressure in the high-pressure oil passage, ensuring safe hydraulic performance.

[Brief description of drawings]

FIG. 1 is an overall plan view of a fluid transmission device according to an embodiment of the present invention.

FIG. 2 is a side view of the same.

FIG. 3 is a sectional view taken along line III-III in FIGS. 1 and 2.

FIG. 4 is a sectional view taken along line IV-IV in FIGS. 1 and 2.

FIG. 5 is a rear view of the cylinder block.

6 is a cross-sectional view taken along line VI-VI in FIG.

FIG. 7 is a view on arrow VII in FIG.

FIG. 8 is a sectional view of a conventional hydraulic motor.

[Explanation of symbols]

1 ... Fluid transmission device, 2 ... Hydraulic pump, 3
... hydraulic motor, 4 ... casing, 5, 6 ... casing side wall, 11 ... pump input shaft, 12 ... cylinder block, 13 ...
Cylinder, 14 ... Piston, 17 ... Swash plate, 18 ... Control bar, 19 ... Control lever, 20 ... Joint member, 31 ... Motor output shaft, 32, 33 ... Sealing member, 40 ... Cylinder block, 41 ... Fitting hole, 42 ... Cylinder, 43 ... Bottom wall, 44 ... Port, 45 ... Groove, 50 ... Piston, 51 ... Swash plate, 55
… Breather member, 56… Cap.

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[Procedure amendment]

[Submission date] March 9, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

A control bar 18 is inserted through the casing side wall 6 in a direction orthogonal to the pump input shaft 11.
Has its end rotatably supported by the casing 4, and the swash plate 17 is rotatably attached to the inner peripheral edge of the hole 18a formed in the bent portion of the control bar 18, and the hole 18a,
The pump input shaft 11 penetrates the annular swash plate 17.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

A control lever 19 is fitted on the end of the control bar 18 exposed from the casing 6, and the control bar 18 is rotated by swinging the control lever 19 and is rotatably mounted on the bent portion. The tilt angle of the swash plate 17 can be changed, and by changing the tilt angle of the swash plate 17 in this way, the stroke length of the piston 14 can be adjusted to control the hydraulic pressure and the like.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

[0030]

According to the present invention, when an excessive load is applied to the rotary shaft, oil leaked to the sliding contact surface between the cylinder bottom wall and the casing side wall is guided to the groove formed in the spline fitting portion. Since it is collected inside the casing, the cylinder block will not be pushed up excessively, and oil will not leak through the seal to the outside to cause a decrease in hydraulic pressure. It is possible to prevent leakage of cylinder oil to the outside with a simple process to form a groove in either the spline fitting part of the cylinder block or the spline fitting part of the rotary shaft, and it is possible to reduce the cost. The hydraulic system is stable because there is no sudden drop in hydraulic pressure in the high-pressure oil passage.

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

[Figure 8]

Claims (1)

[Claims] 1. A cylinder block having a plurality of cylinders for accommodating pistons formed around a rotation center axis is spline-fitted to the rotation axis, and a casing including the cylinder block rotatably supports the rotation axis, In a hydraulic piston pump / motor in which a head of a piston is brought into contact with a swash plate provided in the casing, and a cylinder bottom wall having a port is slidably brought into contact with a casing side wall, the cylinder block and the rotating shaft are A cylinder oil draining structure for a hydraulic piston pump / motor, characterized in that an axially oriented groove is formed in the spline fitting portion over the entire length of the fitting portion.