JPH0346673B2 - - Google Patents

Description

[Detailed Description of the Invention] A. Purpose of the Invention (1) Industrial Field of Use In a swash plate type hydraulic system, in particular, a cylinder block is rotatably supported in a casing storing lubricating oil. A swash plate inclined with respect to the rotational axis of the cylinder block is arranged to face the cylinder block, and a plurality of plungers arranged in an annular shape around the rotational axis parallel to the rotational axis slide in the axial direction of the cylinder block. A shoe is movably fitted into the cylinder block, and a shoe is swingably connected to the tip of each plunger and slidably contacts the swash plate;
A series of oil holes are formed in the plunger and the shoe, respectively, between a hydraulic pocket recessed in the face of the shoe facing the swash plate and an oil chamber defined between the cylinder block and the plunger. The present invention relates to a swash plate type hydraulic system that is connected through a swash plate type hydraulic system.

(2) Prior Art Conventionally, in such hydraulic systems, shoes are made of materials that have good compatibility with the swash plate from the viewpoint of sliding contact with the swash plate, and have excellent seizure resistance, wear resistance, and heat dissipation properties, such as It is generally made of copper alloy or its sintered material.

(3) Problems to be solved by the invention However, since copper alloys and their sintered materials have low tensile strength, it is necessary to increase the wall thickness of the joint with the plunger, and the inclination angle of the swash plate must be increased. This is not desirable when considering compactness.

Therefore, it is conceivable to form the shoe with iron-based material and only the sliding surface with the swash plate to be made of copper alloy or sintered material, but since iron-based materials have poor heat dissipation properties, The shoe tends to overheat due to the heat generated by friction, and due to this overheating, the oil supplied from the oil chamber to the hydraulic pocket of the shoe is strongly heated by the shoe and tends to generate bubbles, resulting in the oil pressure There is a risk that problems such as the effect of reducing the contact surface pressure between the shoe and the swash plate due to the pocket may be impaired.

Therefore, in order to avoid overheating of the shoe and to suppress the heat generation caused by the friction between the shoe and the swash plate, the plunger's pressing ratio is reduced, which causes another problem of increasing hydraulic oil leakage and reducing volumetric efficiency. be.

The present invention has been made in view of the above circumstances, and it is possible to prevent overheating of the shoe even though the main part of the shoe is made of iron-based material and even without making the pressing ratio of the plunger particularly small. It is an object of the present invention to provide a swash plate type hydraulic system that can effectively prevent the above problems and solve all of the above problems.

B. Structure of the Invention (1) Means for Solving Problems In order to achieve the above object, according to the present invention, a cylinder block is rotatably supported in a casing storing lubricating oil, and a cylinder block is rotatably supported in a casing storing lubricating oil. A swash plate inclined with respect to the rotational axis of the cylinder block is disposed so as to face the cylinder block, and a plurality of plungers arranged in an annular shape around the rotational axis in parallel with the rotational axis are arranged in the axial direction of the cylinder block. A shoe is slidably fitted into the cylinder block and slidably contacts the swash plate at the tip of each plunger. , a swash plate type hydraulic device in which an oil chamber defined between the cylinder block and the plunger is communicated with each other through a series of oil holes drilled in the plunger and the shoe, respectively; , is made of an iron-based material and has a plurality of annular grooves on its outer peripheral surface, and a sliding plate made of a different material from the shoe is fixed to the opposing surface.

(2) Function While ensuring compatibility, seizure resistance, and abrasion resistance with the swash plate of the shoe, the selection of iron-based materials increases the tensile strength of the shoe itself, making it compatible with the plunger of the shoe. It becomes possible to reduce the wall thickness of the joint portion.

In addition, although the shoe is made of iron-based material, which generally does not have good heat dissipation, the special provision of the annular groove makes it possible to enhance the heat dissipation effect of the shoe itself. Even if the ratio is made high, there is no risk of the shoe overheating due to friction with the swash plate, and overheating of the oil introduced into the hydraulic pocket through the oil hole in the shoe is also avoided, preventing oil from flowing out from inside the oil. Since the generation of air bubbles is suppressed, the effect of reducing the contact surface pressure between the shoe and the swash plate by the hydraulic pocket is effectively exhibited.

(3) Embodiments Hereinafter, an embodiment in which the present invention is applied to a swash plate type hydraulic pump will be explained with reference to the drawings. First, in FIG. 1, an input shaft 2 is rotatably supported via a bearing 3, and this input shaft 2
The center portion of the cylinder block 4 is slidably spline-coupled to the cylinder block 4. This cylinder block 4 is rotatably supported by the casing 1 via a bearing 5. Further, in the casing 1, a swash plate 6 is installed at one end of the cylinder block 4, and a distribution plate 7 is installed at the other end.

The swash plate 6 has an annular shape surrounding the input shaft 2, and is fitted into a swash plate holder 8, which also has an annular shape and is tiltably supported by the casing 1 via a trunnion shaft 8a. Therefore, the swash plate 6 is tilted together with the swash plate holder 8 around the trunnion shaft 8a, and the inclination angle with respect to the axis of rotation of the cylinder block 4 can be arbitrarily changed.

The distribution plate 7 is fixed to the casing 1 and supports the tip of the input shaft 2 passing through the cylinder block 4 via a bearing 9 at its center. Opposing surface 7 between this distribution plate 7 and cylinder block 4
A spring 1 presses the cylinder block 4 toward the distribution plate 7 in order to bring f and 4f into close contact so that they can slide relative to each other.
0 is compressed between the input shaft 2 and the cylinder block 4.

The cylinder block 4 has a plurality of cylinder holes 11, 11, . .

Each plunger 12 has a corresponding cylinder hole 11
A pump chamber 13 is defined therein, and a pump port 13a connected to the chamber 13 opens to the end surface 4f of the cylinder block 4. And all pump chambers 1
Pump ports 13a, 13a... of 3, 13...
are arranged on the same circle centered on the axis of rotation of the cylinder block 4.

On the other hand, the distribution plate 7 has one half of the end surface 7f,
One suction groove 14 communicating with several pump ports 13a facing thereto is formed, and one discharge groove 15 communicating with several pop ports 13a facing thereon is formed on the other half, and these suction and discharge grooves are formed. Suction and discharge ports 14a and 15a connected to ports 14 and 15, respectively, open at the outer end surface of the distribution plate 7. Although not shown, the suction port 14
The discharge port of the hydraulic motor is connected to a, and the suction port of the hydraulic motor is connected to the discharge port 15a.

In FIG. 2, a spherical end portion 12a is formed at the tip of each plunger 12, and a shoe 16 that slides in sliding contact with the surface of the swash plate 6 is connected to each of these spherical end portions 12a so as to be swingable. .

The shoe 16 is made of iron-based material, and has a plurality of, for example, two annular grooves 2 on its outer peripheral surface.
6 is provided. A hydraulic pocket 21 is provided on the surface of the shoe 16 facing the swash plate, and a sliding plate 27 made of copper alloy, sintered material thereof, etc. is provided on the opposite surface except for the hydraulic pocket 21.
is fixed.

The hydraulic pocket 21 is communicated with the pump chamber 13 through a series of oil holes 22 and 23 formed in the plunger 12 and the shoe 16. Therefore, the pressure oil in the pump chamber 13 is supplied to the hydraulic pocket 21 through the oil holes 22 and 23, and exerts pressure on the shoe 16 to receive the protruding thrust of the plunger 12, so that the sliding plate 27 and the swash plate 6 At the same time, the sliding surfaces of the sliding plate 27 and the swash plate 6 are lubricated.

An annular projecting wall 8b is formed on the outer periphery of the swash plate holder 8, and a presser plate 17 for keeping the shoe 16 in sliding contact with the swash plate 6 is rotatably housed within the annular projecting wall 8b. Ru. Moreover, the presser plate 17 is
Support plate 1 fixed to annular projecting wall 8b with bolts 18
It is rotatably supported by 9. Further, a cylindrical partition body 24 is fitted onto the inner circumference of the swash plate holder 8 and faces the inner circumference surface of the presser plate 17 with a small gap formed between the partition body 24 and the swash plate holder. 8 and the presser plate 17 form a lubricating chamber 25 that surrounds the sliding contact portion between the shoe 16 and the swash plate 6.

Pressure oil is leaking from the hydraulic pocket 21 into the lubrication chamber 25 through the sliding surfaces of the sliding plate 27 and the swash plate 6, and this pressure oil flows into the lubrication chamber 25 as lubricating oil.
After this is filled, it leaks from the gaps in various parts around the presser plate 17. At this time, if the pressure in the lubrication chamber 25 approaches the pressure in the hydraulic pocket 21, the fluid support function of the hydraulic pocket 21 against the shoe 16 will be impaired, so the lubrication chamber 25 should be kept at approximately atmospheric pressure.
A gap between each part around the presser plate 17 is determined.

Next, the operation of this embodiment will be described. Each plunger 12 receives a force in the direction of protruding from the cylinder hole 11 due to the hydraulic pressure in the pump chamber 13, and the shoe 16 is pressed toward the swash plate 6. When the input shaft 2 rotates in this state, the cylinder block 4 rotates around its axis, and as the upper plunger 12 moves downward, it is pressed by the swash plate 6 and retreats. Therefore, the pump chamber 13 at the back of the plunger 12 is reduced in size, and the hydraulic oil pressurized there is delivered to the discharge port 1 of the distribution plate 7.
5a to a hydraulic motor (not shown). On the other hand, as the lower plunger 12 moves upward, it protrudes and the pump chamber 13 at the back of the plunger 12 is enlarged. It is sucked into the pump chamber 13.

In such a hydraulic pump, since the shoe 16 is made of an iron-based material, it has high tensile strength, and therefore the wall thickness of the portion where it is connected to the plunger 12 can be relatively thin. Moreover, by providing the two annular grooves 26 on the outer peripheral surface of the shoe 16, the outer surface area can be increased, and the heat dissipation performance of the shoe 16 can be improved despite the poor heat dissipation properties of iron-based materials. , the volumetric efficiency can be improved by increasing the pressing ratio of the plunger 16. Also, sliding plate 2
By fixing the shoe 7 to the surface of the shoe 16 facing the swash plate 6, it is possible to improve the fit with the swash plate 6 and improve seizure resistance and abrasion resistance.

FIG. 3 shows another embodiment of the present invention, in which a sliding plate 28 formed of the same material as the sliding plate 27 is fixed to the shoe 16 on the surface facing the holding plate 17. be done.

According to this embodiment, not only can the same effects as those of the above-mentioned embodiments be achieved, but also the sliding contact with the presser plate 17 can be improved, so that the operation of the shoe 16 can be made even smoother.

The device of the present invention is applicable not only to the hydraulic pumps described in the above embodiments, but also to a swash plate type hydraulic motor in which a cylinder block and a swash plate are rotated relative to each other by reciprocating a plunger.

C. Effects of the Invention As described above, according to the present invention, a cylinder block is rotatably supported in the casing storing lubricating oil, and a swash plate inclined with respect to the rotational axis of the cylinder block is attached to the cylinder block. A plurality of plungers are arranged so as to face the block and are arranged in an annular shape around the rotational axis in parallel with the rotational axis. A shoe that slides in sliding contact with the swash plate is connected to the tip of the plunger so as to be able to swing freely, and the shoe has a hydraulic pocket recessed in the surface facing the swash plate, and an oil pocket defined between the cylinder block and the plunger. In a swash plate type hydraulic device that is connected to a chamber through a series of oil holes formed in the plunger and the shoe, the shoe has a plurality of annular grooves on its outer peripheral surface. A sliding plate made of iron-based material and made of a material different from that of the shoe is fixed to the facing surface, so that the sliding plate has better compatibility with the swash plate of the shoe, seizure resistance, and wear resistance. By selecting an iron-based material, it is possible to increase the tensile strength of the shoe itself and reduce the wall thickness of the portion where the shoe is connected to the plunger. In addition, although the shoe is made of iron-based material, which generally does not have good heat dissipation, the special provision of the annular groove increases the heat dissipation effect of the shoe itself. Even if the pressing ratio is increased, there is no risk of the shoe overheating due to friction with the swash plate, and overheating of the oil introduced into the hydraulic pocket is also avoided, suppressing the generation of bubbles from the oil. Therefore, there is no risk that the effect of reducing the contact surface pressure by the special installation of the hydraulic pocket will be impaired because the shoe is made of iron-based material, and as a result, the connection between the shoe and the swash plate through the sliding plate is An extremely high-performance swash plate type hydraulic device with extremely smooth sliding contact and high volumetric efficiency can be obtained.

Moreover, the annular groove formed on the outer peripheral surface of the shoe is such that when the shoe passes through the lubricating oil stored in the casing due to rotation of the cylinder block, the inner wall of the groove is arranged along the direction of rotation of the shoe. Therefore, it is possible to efficiently bring the inner wall of the groove into contact with the oil while minimizing the stirring resistance of the oil, and to exhibit high heat dissipation performance.

[Brief explanation of drawings]

1 and 2 show one embodiment of the present invention, FIG. 1 is a longitudinal cross-sectional view of a swash plate type hydraulic pump, and FIG. 2 is an enlarged longitudinal cross-sectional view showing the connecting portion of the shoe and plunger. The plan view and FIG. 3 are longitudinal sectional views corresponding to FIG. 2 of another embodiment of the present invention. 4...Cylinder block, 6...Swash plate, 12...
...Plunger, 16...Show, 13...Pump chamber as oil chamber, 21...Hydraulic pocket, 22,
23...oil hole, 26...annular groove, 27...sliding plate.

Claims (1)

[Claims] 1 Inside the casing 1 storing lubricating oil, a cylinder block 4 is rotatably supported.
A swash plate 6 inclined with respect to the rotational axis of the cylinder block 4 is disposed so as to face the cylinder block 4, and a plurality of plungers 12 are arranged in a ring shape around the rotational axis parallel to the rotational axis.
The cylinder block 4 is slidable in the axial direction.
A shoe 16 is fitted to the tip of each plunger 4 and is swingably connected to the shoe 16 in sliding contact with the swash plate 6, and a hydraulic pocket 21 recessed in the surface of the shoe 16 facing the swash plate 6; Said cylinder block 4
and an oil chamber 13 defined between the plunger 12 in a swash plate type hydraulic system in which the plunger 12 and the oil chamber 13 are communicated through a series of oil holes 22 and 23 formed in the plunger 12 and the shoe 16, respectively, The shoe 16 has a plurality of annular grooves 26 on its outer peripheral surface and is made of iron-based material, and a sliding plate 27 made of a different material from the shoe 16 is fixed to the opposing surface. A swash plate type hydraulic device.