JPS62274106A - Sealing device for hydraulic actuator - Google Patents

Abstract

PURPOSE:To heighten reliability by providing two seals, one behind another around the cylinder wall, through which a piston runs, and connecting a vent circuit provided with an orifice and a check valve to the portion between the seals. CONSTITUTION:Two seals 3 are provided one behind another around the cylinder wall 2 through which a piston 1 runs, and a vent circuit 6 provided with an orifice 7 and a check valve 8 is connected to the portion between the two seals 3. In this way, the oil in the middle portion 4 is discharged through the orifice 7 and the check valve 8, so high pressure is prevented, and the sealing performance is improved. Also, even if the outer seal 3 of a double seal is damaged, there occurs no exterior leak from a return-pressure circuit. Therefore, reliability is improved.

Description

[Detailed description of the invention] 3.1 Detailed description of the invention [Industrial application field] The present invention relates to a sealing device for a hydraulic actuator.

[Conventional technology]

Conventionally, a sealing device for a cylinder wall through which a piston passes through in a hydraulic actuator includes a cylinder wall 2 through which a piston 1 passes, for example, as shown in the vertical cross-sectional view of FIG.
There is one in which two seals 3.3 are placed in the area, a vent circuit 6 is connected to return the pressure 5 between the seals 4, and an orifice 7 is provided in the vent circuit 6. In a device such as this, in which the double seal is connected to a vent circuit that returns the return pressure via an orifice, the seal performance is good because high pressure does not occur between the seals, but if the outer seal is damaged and the This has the disadvantage of causing external leakage.

[Problem that the invention seeks to solve]

The present invention was proposed in view of these circumstances, and
To provide a sealing device for a hydraulic actuator which has good sealing performance, does not cause external leakage from a return pressure circuit even if an outer seal of a double seal is damaged, and is highly reliable.

[Means for solving problems]

To this end, the present invention provides two seals in parallel on the cylinder wall through which the hydraulic actuator piston passes.
The present invention is characterized in that a vent circuit for returning to the return pressure is connected to the space between the two seals, and an orifice and a check valve are disposed in the vent circuit.

[For production]

With the above configuration, it is possible to obtain a sealing device for a hydraulic actuator that has good sealing performance, does not leak externally from the return pressure circuit even if the outer seal of the double seal is damaged, and is highly reliable. .

〔Example〕

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view thereof.

In the above figure, the same symbols as in Fig. 2 indicate the same members as in the same figure, and two seals 3, 3 are arranged side by side on the cylinder wall 2 through which the actuator piston 1 passes, creating a double seal structure. A vent circuit 6 for returning pressure 5 is connected to the space 4 between both seals, and an orifice 7 and a check valve 8 are disposed in the vent circuit 6.

In such a device, the intermediate portion 4 of the two seals 3.3 is connected to the return pressure 5 via the orifice 7 of the vent circuit 6 and the check valve 8, so that even during long-term use, the intermediate portion 4 of the two seals 3. Since the oil in section 4 is discharged through orifice 7 and check valve 8, it does not become under high pressure, so the sealing performance is good, and even if the outer seal 3 is damaged, the return pressure 5 can be activated by check valve 8. Oil is prevented from flowing to the seal side, so the return pressure circuit oil does not leak to the outside.

〔Effect of the invention〕

In short, according to the present invention, when two seals are arranged side by side on the cylinder wall through which the hydraulic actuator piston passes, a vent circuit for returning pressure to the cylinder is connected to the space between the two seals, and the vent circuit is connected to the vent circuit. The provision of an orifice and check valve provides good sealing performance and
The present invention is extremely useful industrially because even if the outer seal of the heavy seal is damaged, no external leakage occurs from the return pressure circuit and a highly reliable sealing device for a hydraulic actuator is obtained.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of a sealing device for a hydraulic actuator of the present invention, and FIG. 2 is a longitudinal cross-sectional view showing a conventional sealing device. 1. Hydraulic actuator piston, 2. Cylinder wall, 3. Seal, 4. Area between seals, 5. Return pressure, 6. Vent circuit, 7. Orifice, 8. Check valve. Sub-Agent Patent Attorney Masashi Tsukamoto Document Box 1 Figure 2

Claims (1)

[Claims] Two seals are arranged side by side on the cylinder wall through which the hydraulic actuator piston passes, and a vent circuit for returning pressure is connected between the two seals, and an orifice and an orifice are connected to the vent circuit. A sealing device for a hydraulic actuator characterized by being equipped with a check valve.