JPH0341172Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a reciprocating sealing device used, for example, in a rod packing of a hydraulic cylinder.

(Prior Art) Conventionally, as this type of reciprocating sealing device, there is one shown in FIG. 6, for example. That is, 100 is a rod such as a hydraulic cylinder, and is assembled to the inner periphery of the housing 101 so as to be able to freely reciprocate. On the other hand, 102 is a sealing fluid pressure buffer packing, 103 is a main packing,
They are arranged on the inner periphery of the housing 101 in order from the sealing fluid 104 side to the atmosphere 105 side, spaced apart in the axial direction. Pressure buffer packing 102 is rod 100
Consisting of a resin seal ring 106 that slides on the surface and a back ring 107 that fits around the outer periphery of the resin seal ring 106, it buffers the pressure of a high-pressure sealing fluid 104 such as a hydraulic cylinder and supplies high pressure directly to the main packing 103. is avoided from being added. On the other hand, fluid leaking from the pressure buffer packing 102 is completely sealed by the main packing 103.

In this way, the sealing fluid 104 is double sealed by the pressure buffer packing 102 and the main packing 103 to improve sealing performance, while the gap between the rod 100 and the inner circumference of the housing 101 is As a result, a sealed chamber 108 is formed, and fluid leaking from the pressure buffer packing 102 accumulates in the sealed chamber 108. As a result, as the device is used for a long period of time, a so-called pressure accumulation phenomenon occurs in which the fluid accumulated in the sealed chamber 108 gradually becomes high in pressure. If this happens, the sealing surface pressure of the main packing 103 will become excessive due to the pressure in the sealed chamber 108, increasing the sliding resistance of the rod 101, and in severe cases, there is a risk that the rod 100 will be locked. In order to prevent such pressure build-up, a drain 9 has conventionally been provided in the housing 101 to recover the fluid accumulated in the sealed chamber 108 to prevent pressure build-up, but the device configuration becomes complicated and expensive. becomes.

Therefore, in order to eliminate such pressure accumulation with a simple structure, as shown in FIG. An annular recess 110 formed by cutting diagonally has been proposed. That is, as shown in FIG. 8, the back ring 107 moves toward the sealing fluid 104 side due to the back pressure applied from the sealed chamber 108, tightens the back side of the annular recess 110 of the resin seal ring 106', and closes the annular recess. 110 The resin seal ring 10 is moved around the boundary 106c' between the inner peripheral tapered surface 110a and the sliding surface 106b of the resin seal ring 106' as a fulcrum.
6' to reduce the diameter of the sealed fluid side end 106a' of the resin seal ring 106', and the fluid in the sealed chamber 108 is transferred from the back ring 107 side to the sealed fluid 104.
I moved it back to my side to release the back pressure. In this way, the back pressure accumulated in the sealed chamber 108 can be automatically released.

(Problems to be Solved by the Invention) However, in the case of such a conventional example, since the inner circumferential surface of the annular recess 110 is formed into a tapered surface 110a, the reciprocating motion of the rod 100 is reduced as shown in FIG. Along with this, foreign matter (metal powder, dust, etc.) in the sealing fluid tends to get caught in the sliding surface 106b' of the resin seal ring 106' due to the wedge effect, and the sliding surface is 106b' is damaged, and the surface of the rod 110 is also damaged. Furthermore, the damage to the rod 100 also causes damage to the sealing surface of the main packing 103, leading to a problem of poor sealing.

The present invention was developed to solve the problems of the prior art described above, and its purpose is to prevent foreign matter from entering the sliding surface side without impairing the pressure accumulation prevention function of the pressure buffer packing. It is an object of the present invention to provide a reciprocating sealing device that is capable of reciprocating motion, and to maintain the sealing performance of the sealing device over a long period of time.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a sealing fluid pressure buffer packing and a main packing that completely seals the fluid leaking from the pressure buffer packing. are spaced apart in the axial direction from the sealed fluid side to the atmosphere side on the inner periphery of the housing that supports the shaft relatively reciprocatingly, and the pressure buffer packing is arranged so that its inner periphery is on the shaft surface. It is constructed by combining a resin seal ring that slides into contact with a resin seal ring and a rubber-like elastic back ring that fits on the outer periphery of the resin seal ring, and further includes a sealing fluid side end of the inner peripheral surface of the resin seal ring. In a reciprocating sealing device in which an annular recess is formed by notching the entire circumference of the resin seal ring, an annular recess is provided at the inner end of the annular recess provided in the resin seal ring, and an annular ring rising approximately perpendicularly from the shaft surface and extending radially outward. A right-angled surface was provided.

(Function) As the shaft reciprocates, the shaft surface is squeezed by the right-angled inner edge provided at the far end of the annular recess formed in the resin seal ring of the pressure-absorbing packing. This prevents foreign matter from entering the sliding portion of the resin seal ring. Also, due to the back pressure accumulated between the pressure buffer packing and the main packing, the back of the annular recess of the resin seal ring is tightened by the back ring moving toward the sealed fluid side, and the inner edge of the right-angled surface is used as a fulcrum. Then, the resin seal ring falls toward the sealed fluid side, reducing the sealing function of the back ring and releasing back pressure to the sealed fluid side.

(Example) The present invention will be explained below based on the illustrated example.

In FIGS. 1 to 4 showing a reciprocating sealing device according to a first embodiment of the present invention, 1 is a rod of a hydraulic cylinder as a shaft similar to the conventional example;
It is supported on the inner periphery of the housing 2 so as to be able to reciprocate. On the inner periphery of this housing 2, a pressure buffer packing 3 for buffering the pressure of the pressure oil O to the main packing 4 from the pressure oil O side as a sealed fluid to the atmosphere A side, and a main packing 4 are arranged in the axial direction. The housings 2 are arranged at predetermined intervals, respectively.
It is attached to mounting grooves 5 and 6 carved on the inner peripheral surface.

The pressure buffer packing 3 includes a resin seal ring 31 whose inner peripheral surface is in sliding contact with the surface of the rod 1;
It is constructed by combining an O-ring 32 as a back ring made of a rubber-like elastic body that fits around the outer periphery of the resin seal ring 31 and imparts a sealing force to the resin seal ring 31. The resin seal ring 31 has a cylindrical shape, and its pressure oil side and atmospheric side end surfaces 31c and 31b are connected to the side wall 5a of the mounting groove 5,
5b to restrict movement in the axial direction. An annular recess 7 is provided at the pressure oil side end of the inner circumferential surface of the resin seal ring 31 and is cut out over the entire circumference. At the far end of the annular recess 7, there is provided an annular right-angled surface 8 that rises substantially perpendicularly from the surface of the rod 1 and extends radially outward. The position of the perpendicular surface 8 is formed at approximately the middle of the thickness of the resin seal ring 31 in the axial direction. Further, the inner surface of the annular recess 7 is a tapered surface 9 whose diameter gradually increases from the outer diameter line 8a of the right angle surface 8 toward the axial pressure oil O side. The radial width of the right angle surface 8 is approximately 1/3 of the radial thickness of the resin seal ring 31, and the radius of the pressure oil side end formed in the annular recess 7 of the resin seal ring 31. The minimum wall thickness in the direction is resin seal ring 31
It is approximately 1/2 of the maximum wall thickness of . However, the dimensional relationship is not limited to this. On the other hand, the diameter of the O-ring 32 is smaller than the axial width of the resin seal ring 31, and it can be moved axially on the outer peripheral surface of the resin seal ring 31 within the mounting groove 5 toward the pressure oil O side or the atmosphere A side. It is becoming.
When the pressure oil O is in a high pressure state, the O ring 32 is positioned on the atmosphere side due to the pressure of the pressure oil O, and the sliding surface 31a of the resin seal ring 31 is pressed against the surface of the rod 1, thereby sealing the seal surface. Applying pressure.

On the other hand, the main gasket 4 is U in this embodiment.
Patsukin is used. Of course, it is not limited to the U-packet, but it is also possible to use various formed packings such as O-rings, or a combination of various formed packings and a resin seal ring like the pressure-buffering packing 3. Various other packings commonly used as packings for reciprocating motion may be used.

The pressure oil O is doubly sealed by the main packing 4 and the pressure buffering packing 3, and the gap between the rod 1 and the inner periphery of the housing 2 is sealed by the main packing 4 and the pressure buffering packing 3. A sealed chamber R is configured.

In the reciprocating sealing device configured as described above, when the pressure oil O is at high pressure, the resin seal ring 31 is pressed toward the atmosphere by the pressure of the pressure oil O, and the atmosphere side end surface 31b is turned against the atmosphere side side wall of the mounting groove 5. 5b, and the pressure oil side end surface 31 of the resin seal ring 31.
The O-ring 32 is pressed toward the atmosphere by the pressure of the pressure oil that has entered the back side of the resin seal ring 31 from the gap between the pressure oil side surface 5a of the mounting groove 5 and the pressure oil side surface 5a of the mounting groove 5. The pressure oil O is blocked by coming into close contact with the back surface of the sliding surface 31a, the bottom wall 5c of the mounting groove 5 of the housing 2, and the atmosphere side side wall 5b, and the entire pressure of the pressure oil O is transferred to this pressure buffer packing 3.
is in charge of the matter.

In this state, when the rod 1 moves axially toward the atmosphere A side (rightward in the figure), the resin seal ring 31
The inner surface of the annular recess 7 is filled with pressure oil containing foreign matter such as dust, but the surface of the rod 1 is
As the edge portion 8 on the inner diameter side of the right angle surface 8 moves,
b, thereby preventing foreign matter D in the pressure oil from entering the sliding surface 31a side of the resin seal ring 31. Therefore, there is no risk that the sliding surface 31a of the resin seal ring 31 will be damaged by foreign matter, and good sealing performance can be maintained over a long period of time.

Next, a case will be described in which a pressure accumulation phenomenon occurs due to pressure oil O that has leaked and accumulated in the sealed chamber R formed between the main packing 4 and the pressure buffer packing 3 due to long-term use. When the pressure of the pressure oil O becomes low and the pressure on the sealed chamber R side becomes higher than the pressure of the pressure oil O by a predetermined pressure, the O ring 32 closes the sealed chamber R.
Due to the back pressure generated inside, the pressure oil moves toward the O side, and the back surface of the annular recess 7 of the resin seal ring 31 is tightened by the O ring 32. As a result, right angle surface 8
A moment acts to rotate the resin seal ring 31 in the counterclockwise direction in the figure using the inner end edge portion 8b as a fulcrum, and the pressure oil side end of the resin seal ring 31 contracts in diameter and the O-ring 32 At the same time, the sealing function is reduced, and the sliding surface 31a side expands, and the back pressure in the sealed chamber R is released from the O-ring 32 side. Here, in the present invention, since the resin ring 31 is configured to have a right-angled surface 8, the resin ring 31 easily collapses due to the tension force of the O-ring 32, and the back pressure can be removed.

FIG. 5 shows a pressure buffer packing for a reciprocating sealing device according to a second embodiment of the present invention. The difference from the first embodiment is that
A plurality of notches 10, . The point is that... When the back pressure generated due to the pressure accumulation phenomenon in the sealed chamber R is released through these notches 10, the back pressure is also released from the sliding contact side with the rod 1, thereby increasing the back pressure release effect. This is what I did. The other configurations and functions are the same as those in the first embodiment, so their explanations will be omitted.

In this embodiment, pressure oil has been described as the sealing fluid, but the present invention is not limited to pressure oil and can be applied to sealing high-pressure fluid.

(Effects of the invention) The present invention has the above-mentioned structure and operation.The inner end of the annular recess provided in the resin seal ring constituting the pressure-absorbing packing is formed into a right-angled surface, so that the reciprocating movement of the shaft Along with this, the shaft surface is squeezed by the inner diameter end of the right-angled surface of the resin seal ring, preventing foreign matter from entering the sliding surface of the seal ring, maintaining good sealing performance over a long period of time. be able to. Also, since it has an annular recess,
Even if a pressure accumulation phenomenon occurs between the pressure buffer packing and the main packing, the resin seal ring is moved to the back side of the annular recess of the resin seal ring due to the back pressure generated by the pressure accumulation effect. This has the effect that the pressure accumulation prevention function is not impaired due to the diameter of the sealed fluid side end being reduced.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of a reciprocating sealing device according to a first embodiment of the present invention, FIG. 2 is an enlarged vertical cross-sectional view of a main part of a pressure buffer packing of the device shown in FIG. Fig. 4 is a vertical cross-sectional view of the main part showing the state of foreign matter removal by the pressure buffer packing of the device shown in Fig. 1, and Fig. 4 is a backrest inside the sealed chamber formed between the pressure buffer packing and the main packing of the device of Fig. 1. FIG. 5 is a vertical sectional view of the main part of the pressure buffer packing of the reciprocating sealing device according to the second embodiment of the present invention, and FIG. 6 is the conventional one. FIG. 7 is a vertical cross-sectional view of a main part of another conventional sealing device, and FIG. 8 is a vertical cross-sectional view of a main part showing a state in which back pressure is released by the device of FIG. 7. and FIG. 9 is a longitudinal sectional view of a main part showing a state in which a foreign object is caught in the sliding surface of the pressure buffer packing of the device shown in FIG. 7. Explanation of symbols, 1... Rod (shaft), 2... Housing, 3... Pressure buffer packing, 31... Resin seal ring, 31a... Sliding surface, 32...
O-ring (back ring), 4... Main packing, 7... Annular recess, 8... Right angle surface, 9... Tapered surface, 10... Notch, O... Pressure oil (sealing fluid),
A...atmosphere, R...sealed room.

Claims (1)

[Claim for Utility Model Registration] A sealing fluid pressure buffer seal and a main seal that completely seals the fluid leaking from the pressure buffer seal are placed on the inner periphery of a housing that supports a shaft so that it can move freely in a relatively reciprocating manner. A resin seal ring is arranged at a distance in the axial direction from the sealed fluid side to the atmosphere side, and the pressure buffer gasket is fitted onto the resin seal ring whose inner peripheral surface slides on the shaft surface, and the outer periphery of the resin seal ring. A seal for reciprocating motion is constructed by combining a back ring made of a rubber-like elastic body to fit the seal ring, and further has an annular recess formed by notching the sealed fluid side end of the inner circumferential surface of the resin seal ring over the entire circumference. A reciprocating sealing device, characterized in that an annular right-angled surface rising from the shaft surface at a substantially right angle and extending radially outward is provided at the inner end of the annular recess provided in the resin seal ring. .