JP2021050623A - Swash plate type axial piston pump motor - Google Patents

Abstract

To provide a swash plate type axial piston pump motor that is inexpensive but has excellent accuracy by reducing wear in a sliding part between a piston and a cylinder block.SOLUTION: A swash plate type axial piston pump motor includes: a cylinder block 8 freely rotatably journaled to a body 1 by engaging a rotation shaft 6 in a rotation direction; and multiple pistons 16 arranged in the cylinder block 8 so as to be capable of freely reciprocating and sliding in an axial direction. Both of the cylinder block 8 and the pistons 16 are formed of a ferritic stainless steel. The pistons 16 may be formed of an austenitic stainless steel or copper alloy, instead of a ferritic stainless steel.SELECTED DRAWING: Figure 1

Description

The present invention relates to a swash plate type axial piston pump / motor in which a plurality of pistons are reciprocally slidably arranged in a cylinder block using working water and the reciprocating movement amount of the pistons is set by a swash plate.

In this type of swash plate type axial piston pump / motor, the rotating shaft is rotatably supported on the main body, the rotating shaft and the cylinder block are fixed, and multiple pistons are reciprocated in the axial direction on the cylinder block. Slanted plates that are arranged at equal intervals in the direction and set the reciprocating sliding amount of the piston are fixed to the main body. In the operation of the pump, the piston is reciprocally slid by rotating the cylinder block on the rotating shaft to suck and discharge the working water. Further, in the motor operation, the rotating shaft rotates together with the cylinder block by reciprocating the piston by the water pressure of the supplied working water. Then, as shown in Patent Document 1, the cylinder block is formed of copper alloy, the piston is formed of ceramic, and as shown in Patent Document 2, the cylinder block has a sleeve of a plastic material based on PEEK. The piston has a diamond-like carbon layer to reduce wear at the sliding points between the piston and the cylinder block.

Japanese Unexamined Patent Publication No. 8-247021 Japanese Unexamined Patent Publication No. 2004-3487

However, in the swash plate type axial piston pump / motor of Patent Document 1, since the piston is formed of ceramic, there is a problem that the material is expensive, the processing is difficult, and the processing cost is also high.
Further, in the swash plate type axial piston pump / motor of Patent Document 2, since a plastic material is used for the cylinder block, it is difficult to improve the molding accuracy and the processing accuracy from the sliding portion between the piston and the cylinder block. There was a risk that the amount of leakage would increase.

An object of the present invention is to reduce wear at a sliding portion between a piston and a cylinder block, and to provide an inexpensive and highly accurate swash plate type axial piston pump / motor.

In order to achieve such a problem, the present invention has taken the following measures. That is,
A rotating shaft rotatably supported on the main body, a cylinder block rotatably supported on the main body by engaging with the rotating shaft in the rotational direction, and a plurality of pistons rotatably arranged on the cylinder block in the axial direction. The reciprocating movement amount of each piston is set by contacting a plurality of working chambers formed by each piston and a cylinder block to suck and discharge working water, and the tip of each piston which is arranged in the main body and protrudes from the cylinder block. It includes a swash plate and side plates that are fixedly arranged on the main body and are in sliding contact with the cylinder block to form a pair of intake / exhaust ports through which working water flows, and the cylinder block and piston are both made of ferrite-based stainless steel. That is the swash plate type axial piston pump motor.
Here, the ferritic stainless steel refers to a stainless steel having a chromium content of 11 to 22% and a nickel content of 0.75% or less.

In this case, either one of the cylinder block and the piston may be formed of austenitic stainless steel instead of ferritic stainless steel.
Here, the austenitic stainless steel refers to a stainless steel having a chromium content of 16 to 26% and a nickel content of 3.5 to 28%.

Further, either one of the cylinder block and the piston may be formed of a copper alloy instead of the ferritic stainless steel.
Here, the copper alloy is an alloy having a copper content of 50% or more.
Further, the cylinder block may be formed of ferritic stainless steel.

As described in detail above, in the invention according to claim 1, both the cylinder block and the piston are made of ferritic stainless steel. For this reason, since the cylinder block and the piston can be made of ferritic stainless steel to improve the thermal conductivity, the heat dissipation of the sliding part between the piston and the cylinder block can be improved, and the wear due to the welding wear of the sliding part can be reduced. it can. Further, it is cheaper, easier to process, and more accurate than those using ceramics such as conventional pumps and motors.

Further, in the invention according to claim 2, either one of the cylinder block and the piston is formed of austenitic stainless steel instead of ferritic stainless steel. Therefore, it is possible to reduce adhesive wear by sliding different materials between the ferritic stainless steel and the austenitic stainless steel while maintaining the heat dissipation effect of the sliding portion between the piston and the cylinder block.

Further, in the invention according to claim 3, one of the cylinder block and the piston is formed of a copper alloy instead of the ferritic stainless steel. Therefore, the cylinder block and the piston can be made of a ferritic stainless steel and a copper alloy to have a higher thermal conductivity, the heat dissipation of the sliding portion between the piston and the cylinder block can be further improved, and wear can be reduced.

Further, in the invention according to claim 4, the cylinder block is made of ferritic stainless steel. Therefore, the cylinder block can improve heat dissipation at the sliding contact portion with the side plate, and can reduce wear at the sliding contact portion with the side plate.

It is a vertical cross-sectional view of the swash plate type axial piston pump motor which showed one Embodiment of this invention.

Hereinafter, an embodiment of the present invention in which the swash plate type axial piston pump / motor is used as the swash plate type axial piston pump will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a main body, which is formed by closing both end openings of a cylindrical tubular member 2 with a front lid member 3 and a rear lid member 4 to form a space F inside. The main body 1 sandwiches the tubular member 2 between the lid members 3 and 4, and fastens the lid members 3 and 4 with a plurality of bolt members 5. Reference numeral 6 denotes a rotating shaft rotatably supported by the front lid member 3 of the main body 1, which penetrates the front lid member 3 and projects the tip to the outside and the rear end to the space F. The rotating shaft 6 has a key 7 at the tip thereof that is coupled to an electric motor (not shown), and at the rear end a spline 9 that engages with a cylinder block 8 described in detail later in the rotational direction.

Two bearings 10 and 11 that rotatably support the rotating shaft 6 are arranged on the front lid member 3 of the main body 1 so as to be separated from each other outward and inward in the axial direction. The bearing 10 arranged outward in the axial direction is a radial ball bearing and is exposed to the outside. The bearing 11 arranged inward in the axial direction is a sliding bearing formed in a tubular shape from a resin material, and the brim portion 11A held at the tip is engaged with the step portion 3A of the front lid member 3 to be positioned in the axial direction. Reference numeral 12 denotes a mechanical seal, which is arranged between the radial ball bearing 10 and the slide bearing 11 and inserts the rotating shaft 6 to seal the insertion portion. The mechanical seal 12 is sandwiched between the bearings 10 and 11 and positioned in the axial direction.

The front lid member 3 forms an inner end surface facing the space F on the inclined surface 3B. A disk-shaped swash plate 13 is fixed to the inclined surface 3B, and the rotating shaft 6 loosely fits the axis of the swash plate 13. The inclined surface 3B is inclined by a constant angle α with respect to the line L orthogonal to the axis G of the rotating shaft 6. A support shaft 14 is fixedly provided on the rear lid member 4, and the support shaft 14 projects toward the space F. The support shaft 14 is provided with three externally fitted, a first sliding bearing 15A, a second sliding bearing 15B, and a third sliding bearing 15C formed in a tubular shape from a resin material. The cylinder block 8 is opened on one end surface to form a support hole 8A in the axial center, and the support shaft 14 is fitted and inserted into the support hole 8A. The cylinder block 8 is rotatably supported on the support shaft 14 by the first slide bearing 15A, the second slide bearing 15B, and the third slide bearing 15C.

The cylinder block 8 opens at the other end surface facing one end surface to form a spline groove 8B at the axial center, and opens at the other end surface to form a plurality of piston holes 8C at equal intervals in the circumferential direction on the outer peripheral side in the radial direction. Form. The spline 9 of the rotating shaft 6 is engaged with the spline groove 8B, and the cylinder block 8 is rotationally driven by the rotating shaft 6. A piston 16 is fitted and inserted into each piston hole 8C so as to be slidable in the axial direction to form a partition for the operating chamber 17. Both the cylinder block 8 and the piston 16 are formed from the ferritic stainless steel SUS430 specified in Japanese Industrial Standard JIS G4303: 2012 "Stainless Steel Rod". The cylinder block 8 and the piston 16 may be SUS403, SUS447J1 or the like instead of SUS430 as long as they are ferrite stainless steel. Each piston 16 comes into contact with the swash plate 13 via a shoe 18 pivotally attached to the tip end portion. The swash plate 13 sets the reciprocating momentum of each piston 16 based on the tilted angle α. The spring force of the spring 19 is applied to each shoe 18 via the retainer 20 and the retainer plate 21, and is pressed against the swash plate 13.

The volume of the working chamber 17 increases due to the forward movement of each piston 16 to the right in FIG. 1 to suck in the working water, and the volume decreases due to the double movement of each piston 16 to the left in FIG. Is discharged. Connection holes 22 are connected to each operating chamber 17, and each connection hole 22 opens at one end surface of the cylinder block 8 at equal intervals in the circumferential direction. The side plate 23 that is in sliding contact with one end surface of the cylinder block 8 is formed of a resin material and fixed to the inner end surface of the rear lid member 4 that faces the space F, and the support shaft 14 inserts the axis. A pair of intake / exhaust ports 24A and 24B are formed through the side plate 23, and both intake / exhaust ports 24A and 24B are arranged in a semicircular shape at symmetrical positions with respect to the axis of the side plate 23.

One of the suction / exhaust ports 24A communicates with the working chamber 17 whose volume increases due to the forward movement of the piston 16 and functions as a suction port for circulating the working water sucked into the working chamber 17. The other suction / exhaust port 24B communicates with the operating chamber 17 whose volume is reduced by the repulsion of the piston 16 and functions as a discharge port for circulating the working water discharged from the operating chamber 17. 25A and 25B are a pair of intake / exhaust flow paths formed in the rear lid member 4, one intake / exhaust flow path 25A is connected to one intake / exhaust port 24A that functions as an suction port, and the other intake / exhaust flow path 25B functions as a discharge port. Connect to the other intake / exhaust port 24B.

Next, the operation of such a configuration will be described.
When the rotary shaft 6 is rotationally driven in the state of FIG. 1, the cylinder block 8 rotates together with the rotary shaft 6. As the cylinder block 8 rotates, each piston 16 reciprocates with a reciprocating momentum according to the inclination angle α of the swash plate 13, and the volume of each operating chamber 17 is increased or decreased.

Working water is sucked into the operating chamber 17, whose volume increases due to the rotation of the cylinder block 8, through the intake / exhaust port 24A through the intake / exhaust flow path 25A. Further, the working water in the working chamber 17, whose volume is reduced by the rotation of the cylinder block 8, flows through the suction / exhaust port 24B and is discharged from the suction / exhaust flow path 25B. In this way, as the cylinder block 8 rotates, the pump operates to continuously suck and discharge the working water. Then, when the rotary drive of the rotary shaft 6 is stopped, the pump operation is stopped.

In this operation, both the cylinder block 8 and the piston 16 are made of ferritic stainless steel. Therefore, since the cylinder block 8 and the piston 16 can improve the thermal conductivity, the heat dissipation of the sliding portion A between the piston 16 and the cylinder block 8 can be improved, and the wear due to the welding wear of the sliding portion A can be reduced. Can be done. Further, it is cheaper, easier to process, and more accurate than those using ceramics such as conventional pumps and motors.

Further, the cylinder block 8 was formed of ferritic stainless steel. Therefore, the cylinder block 8 can improve the heat dissipation of the sliding contact portion B with the side plate 23, and can reduce the wear of the sliding contact portion B with the side plate 23.

As another embodiment of the present invention, the piston 16 is formed from the austenitic stainless steel SUS304 specified in Japanese Industrial Standard JIS G4303: 2012 "Stainless Steel Rod". As a result, the austenitic stainless steel piston 16 slides on the ferritic stainless steel cylinder block 8 while maintaining the heat dissipation effect of the sliding portion A between the piston 16 and the cylinder block 8, so that different materials can be slid. Therefore, ferritic wear can be reduced. Further, since the cylinder block 8 is made of ferritic stainless steel, it is possible to reduce the wear of the sliding contact portion B with the side plate 23 as in one embodiment. The piston 16 may be SUS201, SUS890L, or the like instead of SUS304 as long as it is austenitic stainless steel.

As yet another embodiment of the present invention, the piston 16 is formed from bronze as a copper alloy. Therefore, the ferritic stainless steel cylinder block 8 and the bronze piston 16 can have higher thermal conductivity, the heat dissipation of the sliding portion A between the piston 16 and the cylinder block 8 can be further improved, and wear can be reduced. it can. Further, since the cylinder block 8 is made of ferritic stainless steel, it is possible to reduce the wear of the sliding contact portion B with the side plate 23 as in one embodiment. The piston 16 may be brass, cupronickel, or the like instead of bronze as long as it is a copper alloy.

In each of the above-described embodiments, the cylinder block 8 is made of ferritic stainless steel and the piston 16 is made of ferritic stainless steel, austenitic stainless steel or copper alloy, but the piston 16 is made of ferritic stainless steel and the cylinder block 8 is used. May be ferritic stainless steel, austenitic stainless steel or copper alloy. Further, although the swash plate type axial piston pump / motor is a swash plate type axial piston pump, a swash plate type axial piston motor may also be used. In this case, the cylinder block 8 is rotationally driven by the working water supplied from the outside, and the rotating shaft 6 is rotated by the cylinder block 8. Further, although the constant capacitance type in which the inclination angle of the swash plate 13 is a constant angle α is used, it is needless to say that the variable capacitance type in which the inclination angle of the swash plate can be changed may be used.

1: Main body 6: Rotating shaft 8: Cylinder block 13: Swash plate 16: Piston 23: Side plates 24A, 24B: Intake and exhaust ports A: Sliding points B: Sliding points

Claims (4)

A rotating shaft rotatably supported on the main body, a cylinder block rotatably supported on the main body by engaging with the rotating shaft in the rotational direction, and a plurality of pistons rotatably arranged on the cylinder block in the axial direction. The reciprocating movement amount of each piston is set by contacting a plurality of working chambers formed by each piston and a cylinder block to suck and discharge working water, and the tip of each piston which is arranged in the main body and protrudes from the cylinder block. It includes a swash plate and side plates that are fixedly arranged on the main body and are in sliding contact with the cylinder block to form a pair of intake / exhaust ports through which working water flows, and the cylinder block and piston are both made of ferrite-based stainless steel. Slanted plate type axial piston pump / motor. The swash plate type axial piston pump / motor according to claim 1, wherein either one of the cylinder block and the piston is formed of austenitic stainless steel instead of ferritic stainless steel. The swash plate type axial piston pump motor according to claim 1, wherein either one of the cylinder block and the piston is formed of a copper alloy instead of ferritic stainless steel. The swash plate type axial piston pump motor according to any one of claims 1 to 3, wherein the cylinder block is made of ferritic stainless steel.

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