JPH0512525Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a wear ring in a hydraulic cylinder.

Generally, a hydraulic cylinder has a seal ring 3 as a main seal and wear rings 4 and 5 as bearings arranged symmetrically on the left and right sides of the seal ring 3 between a piston part 1 and a cylinder 2, as shown in the first diagram. be.

FIG. 2 is an enlarged view of the piston portion within the notch in FIG. 1.

Next, FIG. 3 is a side view showing only the wear rings 4 and 5, which has a diagonal abutment gap d, and a third
The upper edges of the opposing ends of the mutually opposing wear rings 5 of the abutment gap d seen from the direction of FIG.

Here, the function of the wear ring will be explained. When the hydraulic cylinder slides back and forth, the wear ring has the function of withstanding the lateral load acting on the piston portion and sliding with low friction, that is, serves as a bearing shaft. Therefore, the material used is filled PTFE or phenolic resin, but conventional wear rings of this type are made of resin, which has a higher coefficient of linear expansion than other iron-based structures. Even if the gap d is closed due to temperature rise during operation, frictional heat, etc., the abutment portion 7 must maintain its flow function.

The reason for this is that the joint part 7 of the wear ring
When it comes into close contact with the seal ring 3, which loses its circulation function and instead functions as a seal, a pressure buildup phenomenon occurs between the seal ring 3, which is the original seal, and the protrusion 5a due to pressure loss occurs as shown in Figures 5 and 6. Easy to occur. As this protrusion 5a progresses further, it becomes flaky foreign matter and diffuses into the cylinder 2, causing foreign matter to enter the cylinder 2, or the volume decreases by the amount of the protrusion 5a.

This results in a decrease in the plate thickness t, resulting in contact between the piston 1 and cylinder 2, seizure, galling, etc., resulting in a decrease in functionality, durability, etc.

The joint part 7 of a conventional wear ring is formed as shown in Figure 4, and even if the gap d is tightly fitted, the chamfered parts 6, 6 remain and care is taken to prevent lid pressure from occurring. When the pressure becomes high (Pr≧250Kgf/cm ² ) and high speed (V≧60m/min), an external force (lateral load) accompanied by large vibrations acts at the end of the stroke and at mid-stop, causing plastic deformation of the wear ring due to surface pressure. occurs as the temperature rises, and the conventional joint shape loses its flow function.

This problem can be solved by making the gap d large and selecting a material with high compressive strength, but if the gap d is made large, the degree of passage of foreign matter (contamination) in the oil is high, and the compression In the case of high-strength materials, the embedding of foreign objects will be poor in proportion to the increase in hardness of the material. Therefore, another function required of the wear ring, that is, the function of sealing internal coarse dust, must be fully fulfilled. become unable to do so. This is shown in the normal state in FIG. 7 and in the closed state of the abutment portion 7 under high surface pressure and high temperature in FIG. 8.

The present invention is designed to eliminate the above-mentioned defects. (2) Testing was conducted under high temperature using a test machine that monitored the external force accompanied by vibration at the end of the stroke and during the stroke, and as a result of understanding the actual situation of loss of the joint, It has been found that a shape having a penetrating chamfered portion having an arcuate cross section as shown in FIG. 9 is the best.

Of course, in this case, the gap d is appropriate,
It is assumed that the load conditions are known, but according to the shape of the present invention, the shape changes after close contact from the state shown in Fig. 9 to the state shown in Fig. 10, leaving the chamfered portions 6, 6 and losing the joint. There's nothing to do.

To further explain the above in detail with reference to drawings, Fig. 11A shows an example of a conventional abutment shape, and when the height h of the face facing the abutment is increased, high surface pressure,
At high temperatures, the flow action of the abutment 7 is stopped as shown in FIG. 11B.

Furthermore, when the height h is made smaller as shown in FIG. 12A, the chamfered portions 6, 6 are enlarged, and under high pressure and high temperature, the contact pressure at the portion h becomes excessive, causing the crack 10.
There is a risk that this may occur. (Figure 12B and 12C
Fig. 13A shows an embodiment of a joint in which a through chamfer with an arcuate cross section is chamfered according to the present invention. The chamfer has an arcuate cross-section, allowing for a large opening area (chamfer area), and as shown in Figure 13B, high surface pressure,
Even under high temperatures, the flow path in the abutment portion 7 is secured and the pressure distribution function is not lost.

Figure 14A shows another embodiment of the invention, in which the height h is the same as in the previous example;
Although the chamfered portions 6, 6 are slightly wider,
As shown in FIG. 14B, even under high surface pressure and high temperature, the pressure release function can be maintained without losing the flow path of the abutment portion 7, and smooth piston operation can be maintained.

In short, in conventional linear chamfering, if the height h is decreased and the chamfered area is increased, the surface pressure of the abutting portion increases, and there is a risk of cracking.

Furthermore, if a sufficient height h is ensured, the chamfered area of the joint will be reduced, and the pressure release function will be reduced or lost.

However, as mentioned above, since the present invention secures a sufficient height h and is formed in an arc shape passing through the chamfered portions 6, 6, it is possible to adopt a chamfered area much larger than that of the conventional one. Therefore, it is possible to appropriately avoid cracks and loss of joints, and it has excellent characteristics that can be used in hydraulic cylinders to increase high efficiency and durability, and is extremely useful in practical use. be.

[Brief explanation of the drawing]

Figure 1 is a partially cutaway side view of a hydraulic cylinder equipped with a conventional piston, Figure 2 is an enlarged view of the piston inside the notch in Figure 1, and Figure 3 shows a pair of its wear rings taken out. A side view, FIG. 4 is a sectional view taken along the line A-A in FIG.
Fig. 6 is an explanatory diagram of the lid pressure state of the same part, Figs. 7 and 8 are explanatory diagrams showing changes in the joint part of the conventional product, and Figs. 9 and 10 are the wear that is the basis of the present invention. Explanatory diagram showing changes in the ring joint part, 1st
Figures 1A and B are explanatory diagrams showing the shape and changes of an example of a conventional joint part, Figures 12A, B, and C are explanatory diagrams showing the formation and changes of another example of the conventional joint part, and Figures 13A
The figure is a partially cutaway side view of the abutment part showing an embodiment of the wear ring of the present invention, FIG. 13B is a partially cutaway side view showing changes in the abutment part under high temperature and high pressure, and FIGS. 14A and B. FIG. 2 is a partially cutaway side view showing the shape and change of the abutment portion of another embodiment of the wear ring of the present invention. 1...Piston part, 2...Cylinder, 3...Seal ring, 4...Wear ring, 5...Wear ring, 5a...Opposite end, 5b...Protrusion, d
... joint gap, 6 ... chamfered part, 7 ... joint part.

Claims (1)

[Scope of utility model registration request] A piston seal structure with a seal ring as the main seal and a resin wear ring as a bearing, characterized in that an axially penetrating chamfered portion with an arcuate cross section is formed on the outer periphery of the wear ring at the abutment of the wear ring. Wear rings in hydraulic cylinders.