JPH09217675A - Swash plate axial piston pump motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve lubricity of a spline. SOLUTION: It is constituted to be furnished with a housing 2 the inside of which is filled with working oil, a rotation axis 10 supported on the housing 2 through bearings 6, 7 free to rotate an one end part of which is stored in the inside of the housing 2, a swash plate 12 inclined against the rotation axis 10, a cylinder barrel 14 fit on an outer periphery of the rotation axis 10 through a spline 13 and to rotate with its end surface making contact with a valve plate 18 and a piston 16 provided in the cylinder barrel 14 free to rise and set in the axial direction and a head part of which makes contact with a sliding surface of the swash plate 12 through a slipper 20. In this case, a working oil inflow hole 35 in which working oil flows as it opens along the axial direction and to one end part end surface of the rotation axis 10 is provided at a central part of the rotation axis 10, and a working oil outflow hole 36 to open along the radial direction, an inner end of which is communicated to the working oil inflow hole 35 and an outer end of which is opened to an outer peripheral surface of the rotation axis 10 in the neighbourhood of the spline 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swash plate type axial piston pump motor.

[0002]

2. Description of the Related Art Japanese Utility Model Laid-Open No. 4-47170 discloses a conventional example of a swash plate type axial piston pump / motor. This type of swash plate type axial piston pump / motor has a housing, a rotary shaft rotatably supported in the housing via bearings, a swash plate inclined with respect to the rotary shaft, and a spline on the outer circumference of the rotary shaft. Cylinder barrel that is fitted and rotated while the end surface is in contact with the valve plate, the axial piston that is retractable inside the cylinder barrel and the head contacts the sliding surface of the swash plate through the slipper, and the cylinder barrel valve A barrel spring that is brought into pressure contact with the plate is provided, and lubrication of each sliding portion is performed by the hydraulic oil filled in the housing.

[0003]

By the way, in the case of the pump / motor of this structure, the rotary shaft and the cylinder barrel are connected by a spline, and the eccentric load, the torsional force, the vibration, and the pressure fluctuation during the operation are connected to the spline. Etc. act directly. Therefore, it can be said that the spline is a site that is extremely susceptible to wear. Therefore, the material, hardness, surface treatment, etc. of the cylinder barrel and rotating shaft are strictly selected to prevent wear.

However, since the cylinder barrel makes a kind of eccentric movement, the spline is likely to run out of oil and is easily worn.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a swash plate type axial piston pump / motor in which the lubricity of the spline is improved.

[0006]

According to a first aspect of the present invention, there is provided a housing whose inside is filled with hydraulic oil, and a rotary shaft which is rotatably supported by the housing via a bearing and has one end housed inside the housing. , Swash plate inclined with respect to the rotary shaft, and fitted through the spline to the outer circumference of the rotary shaft,
A swash plate type having a cylinder barrel whose end surface rotates while in contact with the valve plate, and a piston which is provided in the cylinder barrel so as to be retractable in the axial direction and whose head contacts the sliding surface of the swash plate through a slipper. In the axial piston pump / motor, a central part of the rotary shaft is provided with a hydraulic oil inflow hole into which the hydraulic oil flows by opening along the axial direction and at an end face of one end of the rotary shaft, and at the same time, on the rotary shaft, The above problem is solved by providing a working oil outflow hole along the radial direction, the inner end of which communicates with the working oil inflow hole and the outer end of which opens to the outer peripheral surface of the rotating shaft near the spline. is there.

In this swash plate type axial piston pump / motor, since the inside of the housing is filled with the working oil, the working oil also flows into the working oil inflow hole provided in the rotary shaft. When the pump / motor operates and the rotary shaft rotates, the hydraulic oil flowing into the hydraulic oil inflow hole flows out from the hydraulic oil outflow hole to the outside by the centrifugal force generated by the rotation of the rotary shaft. For this reason, a flow of hydraulic oil that flows in from the hydraulic oil inflow hole and flows out from the hydraulic oil outflow hole is created, and the flow of the hydraulic oil causes the hydraulic oil to flow to the splines near the opening of the hydraulic oil outflow hole. Since it is positively supplied, the lubricity of the spline portion is improved. Since the flow of hydraulic oil becomes faster as the rotational speed of the rotary shaft increases, a large amount of hydraulic oil is continuously supplied to the spline in proportion to the rotational speed, and there is no risk of oil shortage.

According to a second aspect of the present invention, in the first aspect, a space which is adjacent to the axial direction of the spline and which faces the opening of the hydraulic oil outflow hole is secured, and a member which defines this space is provided.
The hydraulic oil flowing out from the opening is guided to the spline side to solve the above problem.

In this pump / motor, the hydraulic oil flowing out from the opening of the hydraulic oil outflow hole is positively guided to the spline side via the space outside thereof. Therefore, the lubricity of the spline is further improved.

According to a third aspect of the present invention, in the second aspect, a coil spring for pressing the cylinder barrel against the valve plate is inserted into a cylindrical gap between the inner periphery of the cylinder barrel and the outer periphery of the rotary shaft, and the space is formed. The above-described problem is solved by the member that defines the spring seat on the rotating shaft side that receives one end of the coil spring.

In this pump / motor, the hydraulic oil is positively guided to the spline side due to the presence of the spring seat on the rotary shaft side.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a swash plate type axial piston pump.
The side section of motor 1 is shown. The housing 2 of the pump / motor 1 is composed of a housing body 3 and an end cover 4 and is liquid-tightly sealed so that the hydraulic oil therein does not leak. The housing body 3 has a through hole 3a at one end through which the rotary shaft 10 projects, and the other end opening 3b has an end cover 4a.
It is closed by.

The rotary shaft (which serves as an output shaft when used as a motor and serves as an input shaft when used as a pump) 10 is
It is rotatably supported by bearings 6 and 7 housed in the housing 2, and a base end portion (one end portion) 10 a is housed inside the housing 2. Inside the housing 2, a swash plate 12 that is inclined with respect to the rotating shaft 10 is provided. The swash plate 12 faces the base end direction of the rotary shaft 10.

A cylinder barrel 14 is provided on the outer periphery of the rotary shaft 10.
And the cylinder barrel 14 is connected to the rotary shaft 10 by a spline 13. The spline 13 is
It is arranged near the swash plate 12. A plurality of cylinders 15 are formed on the circumference of the cylinder barrel 14 at equal intervals along the axial direction, and pistons 16 are inserted into and retractable from each cylinder 15 in the axial direction.
The spherical head 17 of 6 is in contact with the sliding surface of the swash plate 12 via the slipper 20. The slipper 20 is held by a slipper retainer plate 21, and a thrust plate 22 is arranged between the slipper 20 and the swash plate 12. The slipper retainer plate 21 is guided by a guide ball 23 fitted to the outer periphery of the rotary shaft 10 via the spline 13.

A valve plate 18 is attached to the inner wall of the housing 2 that faces the swash plate 12 with the cylinder barrel 14 in between, and the end surface of the cylinder barrel 14 contacts while rotating. The valve plate 18 has a main port A,
This is for switching the communication of the oil passage between B and the cylinder 15 in the cylinder barrel 14, and is prevented from rotating by a pin 19.

A cylindrical clearance 24 is secured between the inner circumference of the cylinder barrel 14 and the outer circumference of the rotary shaft 10, and there is
A barrel spring (coil spring) 25 for pressing the cylinder barrel 14 against the valve plate 18 is inserted. One end of the barrel spring 25 is received by a spring seat 27 stopped on the cylinder barrel 14 side by a snap ring 26, and the other end of the barrel spring 25 is stopped on the rotary shaft 10 side via a spacer pin (not shown). It is received by the seat 28.
In this case, the spacer pin provides a predetermined space 29 between the spring seat 28 on the rotary shaft 10 side and the spline 13.
Is secured. However, as long as the space 29 can be secured and the spring seat 28 of the barrel spring 25 can be reliably received, the structure may be any other than this structure.

Further, as a hydraulic oil passage for positively feeding the hydraulic oil filled in the internal space 30 of the housing 2 to the spline 13, the groove 31 on the rear surface side of the valve plate 18 and the inner peripheral side of the valve plate 18 are provided. Through hole 32
And an oil sump 33 that is in contact with the end face of the base end portion 10a of the rotary shaft 10, and the hydraulic oil inlet hole 35 is provided in the rotary shaft 10.
And a hydraulic oil outflow hole 36 are provided.

The hydraulic oil inflow hole 35 is bored along the axial direction at the center of the base end portion 10a of the rotary shaft 10 and opens at the shaft end face so that the hydraulic oil can flow into the inside. .
The hydraulic oil outflow hole 36 is bored in the radial direction of the rotary shaft 10, the inner end communicates with the rear end of the hydraulic oil inflow hole 35, the outer end opens to the outer peripheral surface of the rotary shaft 10, and the opening is the spline 13. Faces a space 29 defined between the spring seat 28 and the spring seat 28. A plurality of hydraulic oil outflow holes 36 may be provided in the circumferential direction, or only one may be provided.

Next, the operation will be described. For convenience, the operation when the pump / motor 1 is used as a motor will be described.

When high-pressure oil flows in from the main port A,
It enters into the cylinder 15 of the cylinder barrel 14 via the valve plate 18. This high-pressure oil acts on the piston 16,
The slipper 20 pushes the swash plate 12 by the axial movement of the piston 16 and causes the cylinder barrel 14 to generate a rotational force. As a result, a rotational force is applied to the rotary shaft 10 connected by the cylinder barrel 14 and the spline 13. The low-pressure oil after operation flows out from the main port B via the valve plate 18.

By the way, in this operation, since the internal space 30 of the housing 2 is filled with hydraulic oil in advance,
Substantially all the components inside the housing 2 are immersed in the hydraulic oil. Therefore, the groove 3 on the rear surface side of the valve plate 18
1, the through hole 32, the oil sump 33, of course, the rotary shaft 10
Hydraulic oil inflow hole 35, hydraulic oil outflow hole 36, spline 1
3 is also filled with hydraulic oil.

In this state, when the rotary shaft 10 rotates, the hydraulic oil inside the rotary shaft 10 is centrifugally acted upon by the centrifugal force, and the hydraulic oil outflow hole 36
Flows into the outside space 29. For this reason, as shown by the arrow in the figure, a flow of the hydraulic oil that flows in from the hydraulic oil inflow hole 35 and flows out from the hydraulic oil outflow hole 36 is created, and the flow of the hydraulic oil causes the opening of the hydraulic oil outflow hole 36. The hydraulic oil is positively supplied to the spline 13 in the vicinity of, and the lubricity of the spline 13 portion is improved.

In this case, one end of the space 29 on the side opposite to the spline 13 is partitioned by the presence of the spring seat 28, so that most of the hydraulic oil flowing into the space 29 due to the increase in flow passage resistance is in the spline 13. Will be actively guided to the side. As a result, the amount of hydraulic oil flowing through the spline 13 is increased, and the lubricity is further improved. Further, the flow of the hydraulic oil becomes faster as the rotation speed of the rotating shaft 10 increases, so that the spline 13 is proportional to the rotation speed.
A large amount of hydraulic oil will be supplied to the oil, eliminating the risk of running out of oil.

Here, the inlet side up to the hydraulic oil inlet hole 35 passes from the internal space 30 of the housing 2 through the groove 31 and the through hole 32 on the rear surface side of the valve plate 18, the bearing 6, and the oil sump 33. The flow of hydraulic oil
The required flow is ensured.

If the inlet and outlet of the main port are reversed, the directions of rotation will be opposite, and the rotation shaft 10 will be rotated to
If the piston 16 is reciprocated, it can be used as a pump as usual.

[0027]

As described above, according to the first aspect of the invention, the centrifugal force generated by the rotation of the rotary shaft is utilized to positively generate the oil flow for feeding the hydraulic oil to the spline. Lubricity can be improved and spline wear can be further prevented. As a result, the surface treatment of the cylinder barrel and the spline portion of the rotary shaft and the material selection criteria can be relaxed, and the requirements for processing accuracy can be relaxed.

If a space is secured outside the opening of the hydraulic oil outflow hole so that the hydraulic oil is positively guided to the spline side, the lubricating effect can be further enhanced. Further, as the member for guiding, a spring seat can be used as in the invention of claim 3.

[Brief description of drawings]

FIG. 1 is a sectional view of a swash plate type axial piston pump / motor according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Swash plate type axial piston pump / motor 2 ... Housing 6,7 ... Bearing 10 ... Rotating shaft 10a ... Base end part (one end) 12 ... Swash plate 13 ... Spline 14 ... Cylinder barrel 16 ... Piston 17 ... Head 18 ... Valve plate 20 ... Slipper 25 ... Barrel spring (coil spring) 28 ... Spring seat 29 ... Space 35 ... Operating oil inflow hole 36 ... Operating oil outflow hole

Claims (3)

[Claims] 1. A housing whose inside is filled with hydraulic oil, a rotary shaft rotatably supported by the housing via a bearing, and one end of which is housed inside the housing, and a slanted inclined with respect to the rotary shaft. A plate, a cylinder barrel fitted to the outer periphery of the rotary shaft via a spline, and rotating while the end face contacts the valve plate; A swash plate type axial piston pump / motor having a piston that comes into contact with a sliding surface of the swash plate, wherein the operation is performed by opening a central portion of the rotary shaft along an axial direction and at an end face of one end of the rotary shaft. A hydraulic oil inflow hole through which oil flows is provided, and the rotary shaft extends radially and an inner end communicates with the hydraulic oil inflow hole and an outer end near the spline. Swash plate type axial piston pump motor, characterized in that the hydraulic oil flowing out hole opened on the rolling shaft outer circumferential surface is provided. 2. The space according to claim 1, wherein a space facing the opening of said hydraulic oil outflow hole is secured adjacent to the axial direction of said spline, and a member defining this space prevents the hydraulic oil flowing out from said opening. A swash plate type axial piston pump / motor characterized by being guided to the spline side. 3. A member defining the space according to claim 2, wherein a coil spring for pressing the cylinder barrel against the valve plate is inserted into a cylindrical gap between the inner circumference of the cylinder barrel and the outer circumference of the rotary shaft. Is a spring seat on the rotating shaft side for receiving one end of the coil spring, and a swash plate type axial piston pump / motor.