JPS63167179A - Sealing system for rod - Google Patents

Abstract

PURPOSE:To prevent deformation of any sealing component, by supplying a pressure from the outside of a cylinder into a hole which is made in a seal holder to reduce a relative pressure applied on the sealing component. CONSTITUTION:An opening 11 is formed on an inside wall surface near the center position between a recess 4 and a recess 5 made in a seal holder 1 and also a hole 13 opened to the outside of a cylinder 10 is formed. The hole 13 is connected to a pass 14 and the pass 14 is connected to a tank 16 through a pump 15. Therefore, a pressure difference occurs between seal components, namely a seal 7 and a U ring 8. Consequently, if the cylinder room side of the seal 7 is pressurized following the pressure rise in a cylinder chamber A, a pressure supplied from the outside of the cylinder is added to the cylinder edge side of the seal 7, then the relative pressure applied on the seal 7 is reduced and deformation of the seal 7 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rod seal system for a high-pressure hydraulic cylinder used in construction machinery and the like.

(Prior Art) A conventional rod seal system has a hole 2 that passes through a seal holder 1 fixed at the end of the cylinder, as shown in FIG.
Two recesses 4.5 are provided on the inner peripheral surface of the rod 3 so as to surround the rod 3. Although not shown in FIG. 4, the rod 3 has a piston on its right side and communicates with the cylinder chamber, and its left side projects outside the cylinder. A seal 7 is inserted into the recess 4 on the cylinder chamber side through a ring 6, and the seal 7 is formed in a cylindrical shape with a hole in the center through which the rod 3 passes, and the inner peripheral surface thereof has a triangular cross section. lip portion 7a of
, and its top abuts against the rod 3. Furthermore, the angle (lip angle) between the outer surface of the rod 3 and the seal 7 at this contact position is α,
The angle at the opposite end of the cylinder is defined as β, and these angles are formed in the relationship α)β, resulting in a structure that prevents oil from leaking from the cylinder chamber to the outside of the cylinder.

A U-ring 8 is inserted into a recess 5 on the cylinder end side provided in the seal holder 1, and a portion of the inner circumference of the U-ring 8 comes into contact with the rod 3.

When the pressure in the cylinder chamber becomes high, oil in the cylinder chamber enters the gap between the rod 3 and the seal holder 1, pushes the lip portion 7a of the seal 7 toward the cylinder end, deforms the shape of the seal 7, and flows out of the cylinder. Prevent oil from leaking. Furthermore, if the seal 7 is damaged and oil leaks, the ring 8 is inserted into the recess 5 and seals the oil.

There was also one that used a buffer ring instead of the seal 7.

(Problems to be Solved by the Invention) According to the conventional example, since the seal 7 receives high pressure in the system (for example, 350 Kgf/cd), the amount of deformation of the seal 7 is large and the seal 7 protrudes between the rod 3 and the seal holder 1. This caused the problem that the seal 7 was narrowed and the seal 7 deteriorated.

The present invention has been made in view of the above-mentioned circumstances, and by generating pressure on the cylinder end side of the seal 7 and reducing the relative pressure applied to the seal 7, it prevents deformation of the seal 7 and extends its life. The purpose is to provide an improved rod seal system.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a seal holder that is fixedly installed at the end of the cylinder on the Orad side in order to seal the oil in the cylinder, and a rod of the seal holder. In a hydraulic cylinder in which multiple rows of seal members are provided on a sliding surface, a hole is provided in the seal holder to communicate between the outside of the cylinder and an inner wall surface between the seal members, and pressure is supplied to the hole from the outside of the cylinder. It is characterized by

(Function) Since the present invention is configured as described above, even if pressure is generated in the cylinder chamber and pressure is applied to the cylinder chamber side of the seal member near the cylinder chamber, pressure is applied to the cylinder end side of the seal member from outside the cylinder. , the relative pressure on the sealing member is reduced and prevents its deformation.

(Example) Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows the entire hydraulic cylinder having the rod seal system of the present invention, and FIG. 2 is an enlarged explanatory view of the rod seal system portion of FIG. 1.

A piston 9 is fixed to one end of the rod 3, and the piston 9 is configured to be slidable inside the cylinder 10.
A seal holder 1 is fixed to the end of the cylinder on the side, and the other end of the rod 3 projects outward from a hole 2 provided in the seal holder 1 and passing through the inside and outside of the cylinder 10.

Two recesses 4.5 are provided on the inner peripheral surface of the hole 2 that penetrates the seal holder 1 fixedly installed at the end of the cylinder 10 so as to surround the rod 3, and a ring 6 is installed in the recess 4 on the cylinder chamber A side. The seal 7 is inserted through the hole.

The seal 7 is formed into a cylindrical shape having a hole in the center through which the rod 3 passes, and has a lip portion 7a with a triangular cross section formed on its inner circumferential surface, and the top of the lip portion 7a is in contact with the rod 3. . Furthermore, the angle (lip angle) between the outer surface of the rod 3 and the seal 7 at this contact position is formed so that the angle α on the cylinder intersection A side and the angle β on the cylinder end side have a relationship of α>β. However, the structure prevents oil from leaking from the cylinder chamber A side to the outside of the cylinder 10.

A U-ring 8 is inserted into a recess 5 on the cylinder end side provided in the seal holder 1, and a portion of the inner circumference of the U-ring 8 comes into contact with the rod 3.

The seal holder 1 is provided with an opening 11 on the inner wall surface approximately at the center of the recess 4 and the recess 5 provided in the seal holder 1, and a hole 13 through which the other opening 12 communicates with the outside of the cylinder 10. The hole 13 is connected to a passage 14 which is connected via a pump 15 to a tank 16, thereby creating pressure between the sealing members, ie between the seal 7 and the U-ring 8. A relief 17 is connected to the pump 15 in parallel, and the pressure supplied by the pump 15 to the hole 13 is transferred to the cylinder 9! Set to a value smaller than the pressure.

That is, by adjusting the pressure at which the relief 17 operates, the pressure supplied by the pump 15 can be set to a value suitable for preventing deterioration of the seal 7.

FIG. 3 shows another embodiment, in which a passage 18 communicating with the cylinder cavity is provided, and this passage 18 is connected to the opening 12 of the hole 13 via a pressure reducing valve 19. That is, the pressure generated in the cylinder chamber A is reduced by the pressure reducing pusher 19, and a pressure smaller than the pressure applied to the cylinder chamber is supplied from the hole 13 between the seal members.

Even if the pressure in the cylinder chamber A increases and pressure builds up on the cylinder chamber side of the seal 7, the pressure supplied from outside the cylinder is applied to the cylinder end side of the seal 7, so the seal 7
The relative pressure exerted on the is reduced.

Furthermore, since the pressure supplied between the step seal 7 and the U-ring 8 is always set to be lower than the pressure generated in the cylinder chamber A, oil flows from the cylinder end side of the step seal 7 to the cylinder chamber A side. will not flow backwards.

In addition, in part 4, seal 7 was used as the seal member, but
The present invention is not limited to this, and buffering may be used.

(Effects of the Invention) The present invention is configured such that a hole communicating with the outside is provided in the seal holder between the seal members provided in multiple rows, and pressure is supplied to the hole from the outside of the cylinder.

Therefore, even if pressure is generated in the cylinder chamber and pressure builds up on the cylinder chamber side of the seal member, a pressure smaller than the pressure in the cylinder chamber is applied to the cylinder end side of the seal member.
The relative pressure applied to the seal member is reduced, preventing its deformation, and the deformed seal member is not caught between the rod and the seal holder, preventing deterioration of the seal member and improving durability. .

[Brief explanation of the drawing]

FIG. 1 is a partially cross-sectional explanatory diagram of a cylinder having a rod seal system according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing an enlarged portion of the rod seal system in FIG. FIG. 4 is a partial cross-sectional explanatory view of a cylinder having a rod seal system. FIG. 4 is an explanatory view showing the structure of a conventional rod seal system. 1... Seal holder 3...
Rod 4.5...Concavity 7...Seal 8...U ring 10...
・Cylinder 13・・・・・・Bore 15・
... Pump 19 ...... Pressure reducing valve December 27, 1986

Claims (1)

[Claims] A hydraulic cylinder in which a seal holder is fixed to the end of the cylinder on the rod side in order to seal oil in the cylinder, and multiple rows of seal members are provided on the rod sliding surface of the seal holder. A rod seal system, characterized in that the seal holder is provided with a hole that communicates between the outside of the cylinder and the inner wall surface between the seal members, and pressure is supplied to the hole from the outside of the cylinder.