JPS6116276A - Axial piston machine - Google Patents

Abstract

PURPOSE:To enhance the durability of an axial piston machine, by forming only those of positions in a cylinder block where errosion by cavitation occurs, corresponding to the inside and outside seal lands of a valve plate, with the use of wear-resistant members, and by incorporating those integrally with the cylinder block. CONSTITUTION:An axial piston machine has a cylinder block 5 in which a plurality of cylinder bores 12 are formed at equal intervals along the circumferential direction thereof, each cylinder hole 12 receiving therein a reciprocatable piston. In this arrangement an annular groove 13 is formed in one end face of the cylinder block 5, and a wear-resistant member 20 formed therein with bean- like shape holes 6 which are communicated with their associated cylinder bores 12, is fitted in the annular groove 13. Further, coupling grooves 16 are formed in the inner and outer peripheral sections of the wear-resistant member 20. Further, during assembly of the axial piston machine, after the wear-resistant member 20 being fitted in the annular groove 13 and positioned, the caulking sections 18, 19 of the cylinder block 5 are pressed to integrally incorporate the wear-resistant member 20 with the cylinder block 5 by means of the coupling grooves 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an axial piston machine, particularly to a structure of a cylinder block suitable for a highly water-containing hydraulic fluid.

[Background of the invention]

The conventional axial piston machine, as shown in Figure 6,
Casing body 3A, suction hole 10A and discharge hole 10B
A drive shaft 1 supported by a bearing 2 and a cylinder block 5 having a cylinder hole 21 in which a piston 4 slides are rotatably housed in a casing 3 formed by integrally joining an end plate 9 having a casing 3. A valve plate 7 is interposed between the cylinder block 5 and the end plate 9.

The axis of the cylinder block 5 is inclined with respect to the axis of the drive shaft 1, and the cylinder block 5 is provided with a plurality of cylinder holes 12 at equal intervals in the circumferential direction. The piston 4 is inserted into the hole 12 as described above.
is stored so that it can be moved back and forth. However, in the figure, only one cylinder hole 12 and one piston 4 are shown for the sake of simplicity.

A spherical portion 4A formed at the rond end (left end in the figure) of the piston 4 fits into a spherical recess IB provided in the large diameter portion IA of the drive@1. Further, a layered hole 6 communicating with each cylinder hole 12 is provided in the wall portion of the cylinder block 5 on the valve plate 7 side, and a suction hole 8 communicating with the layered hole 6 is provided in the valve plate 7. It is being The suction hole 8 communicates with the suction port 10A of the end plate 9, and the suction hole 10A and the suction hole 8 are formed to be wider than the layered hole 6.

In the conventional example having the above structure, the cylinder block 5 rotates as the drive shaft 1 rotates, and the reciprocating movement of the piston 4 performs a pumping action. Now, when any piston 4 is in the suction stroke, liquid is sucked into the cylinder hole 12 from the stratified hole 6 via the wide suction port 10A and the suction hole 8.

The suction action during this period affects the self-priming performance of the pump, and at this time, the flow velocity in the layered holes 6 is high and the shape change is significant, resulting in a very large pressure loss. In particular, when the flow velocity is high, bubbles are generated at the corners of the layered holes 6, and cavitation erosion occurs at the 0 part in FIG. It may cause damage and impair the function of the pump.

Further, cavitation erosion occurs on the side surfaces A and B of the layered hole 6 shown in FIG. 8, that is, on the inner and outer walls of the cylinder block 5. This cavitation erosion is caused by a cavitation jet flowing into the cylinder block 5 from the layer boat on the high pressure side of the valve plate 7 when the pressure in the cylinder block 5 is switched from low pressure to high pressure.

Conventionally, as a countermeasure against cavitation erosion as described above, the prior art shown in FIG.
-49104), the entire sliding surface including the bore of the cylinder block 5 is formed of a valve plate 7 having a suction hole 8 made of a highly durable material, and the valve plate 7 and the cylinder block 5 are connected by bolts 11. This was handled by a composite cylinder block structure that was tightened and integrated through the cylinder block.

However, as a result of durability tests conducted on a structure with the above-described measures, it was found that as time passed, high-pressure liquid entered the joint surface 12 between the valve plate 7 and the cylinder block 5. It has been found that the fastening bolt 11 breaks due to fatigue when the high-pressure fluid repeatedly acts on the joint surface 12 as a separating force. Therefore, the above-mentioned prior art has a problem in terms of durability when used for a long time.

[Purpose of the invention]

In view of the above, an object of the present invention is to provide an axial piston machine equipped with a cylinder block having high durability against cavitation erosion.

[Summary of the invention]

In order to achieve the above object, the present invention forms only the portions of the cylinder block where cavitation erosion occurs, that is, the portions of the sliding surface of the cylinder block that correspond to the inner and outer seal lands of the valve plate, from a wear-resistant material. The valve plate provided with the wear-resistant member is inserted into an annular groove provided in the cylinder block, and the inner and outer peripheries of the annular groove are caulked to integrally connect the wear-resistant member and the cylinder block. It is characterized by this.

[Embodiments of the invention]

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

Fig. 1 is a side sectional view showing a typical example of a composite cylinder block of an embodiment of the axial piston machine of the present invention;
The figure is a view taken along the line ■--■ in FIG. 1, and FIG. 3 is a sectional view of the caulked portion of the valve plate.

In FIGS. 1 to 3, reference numeral 5 denotes a cylinder block, and an annular groove 13 is provided in the end surface of the cylinder block 5. As shown in FIGS. Reference numeral 7 denotes a valve plate fitted in an annular groove 13, and this valve plate 7 is provided with a plurality of layered holes 6 concentrically and equally spaced, and furthermore, the inner and outer seal lands 1 of the valve plate 7
Only the portion corresponding to 4.15 is formed of a wear-resistant member. Reference numeral 16 denotes a threaded groove provided in the engagement surface between the valve plate 7 and the annular groove 13 provided in the cylinder block 5.

Other structures are the same as those shown in FIG. 6, so drawings and explanations will be omitted.

When assembling this embodiment with the above configuration,
First, the valve plate 7 having the laminar hole 6 is inserted into the annular groove 13 of the cylinder block 5, and then the laminar hole 6 is inserted into the annular groove 13 of the cylinder block. Position the hole 6.

Next, by pressurizing the caulking portion 1'8.19 of the cylinder block 5, the threaded grooves 16 provided in the inner and outer circumferential portions of the valve plate 7 and the inner circumferential portion of the groove 13 provided in the cylinder block 5 are connected to each other. Therefore, the valve plate 7 and the cylinder block 5 can be integrally connected.

In such a composite cylinder block that is integrally connected, the bonding force in the bonding layer exceeds the separation force that occurs when liquid enters the bonding surface, so that the valve plate 7 does not move during operation. There is no fear of escape. On the other hand, if the thickness of the valve plate 7 is configured to be equal to or less than the parallel portion of the cylinder block bore, the bonding layer can be made even stronger.

4 and 5 are side sectional views of cylinder blocks according to other embodiments of the present invention, and
■It is an arrow view.

In FIGS. 4 and 5, a groove 17 is formed in the cylinder block 5 at the joint surface between the valve plate 7 and the cylinder block 5.
There are several. As shown in FIG. 5, these grooves 17 are located between the layered holes 6 provided in the cylinder block 5.
The annular groove 13 is penetrated from the inner diameter of the annular groove 13 provided in the cylinder block 5 to the outer periphery of the cylinder block 5 .

With this structure, even if liquid were to enter the joint surface, it would flow through the grooves 17 provided between the layered holes 6 and flow out toward the outer periphery of the cylinder block 5, preventing high-pressure liquid from entering the joint surface. Since no liquid remains, the separation force due to liquid intrusion can be suppressed to a minimum.

The material of the valve plate 7 is a metal with high hardness and a dense structure, such as a composite sintered alloy in which TiC is bonded to a Cr-Mo mesh fabric, thereby imparting durability against cavitation erosion. be able to.

Although this embodiment has been described as an embodiment for a diagonal shaft type axial piston pump, the present invention is not limited thereto and can be applied to the cylinder block of any pump.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to provide a composite cylinder block that is highly durable against cavitation erosion, and can operate at high pressure and for long periods of time even when the working fluid is a high water content hydraulic fluid. It can be realized.

Furthermore, since the sliding surfaces of the cylinder block corresponding to the inner and outer seal land portions of the valve plate are good, not only high durability but also basic functions of the pump, such as volumetric efficiency, can be improved.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a composite cylinder block of an embodiment of an axial piston machine according to the present invention, FIG. FIG. 4 is a side sectional view of a cylinder block according to another embodiment of the present invention, FIG. 5 is a view taken along the line mm in FIG. 4, and FIG. A side sectional view of the oblique shaft type axial piston pump, Figure 7 is the same as Figure 6! -1 arrow view, FIG. 8 is a partial side sectional view of FIG. 7, and FIG. 9 is a side sectional view of a conventional cylinder block. 5... Cylinder block, 6... Layered hole, 7... Valve plate, 13... Annular groove, 14, 15... Inner/outer seal land, 16... Thread groove.

Claims (4)

[Claims] 1. In an axial piston machine in which a valve plate is interposed between a cylinder block of a rotor and an end plate having a suction hole and a discharge hole, the sliding surface of the cylinder block corresponds to the inner and outer seal lands of the valve plate. The valve plate having this wear-resistant member is inserted into an annular groove provided in the cylinder block, and the inner and outer periphery of the annular groove is caulked to form the wear-resistant member. An axial piston machine characterized in that a flexible member and a cylinder block are integrally connected. 2. The axial piston machine according to claim 1, characterized in that a thread groove is provided on the engagement surface of the wear-resistant portion of the valve plate and the cylinder block. 3. 3. The axial piston machine according to claim 1, wherein the wear-resistant portion of the valve plate is thinner than the parallel portion of the cylinder block bore. 4. In the axial piston machine according to any one of claims 1 to 3, the material of the wear-resistant member is a composite sintered alloy in which TiC is bonded to a Cr-Mo steel material. An axial piston machine comprising: