JPH0128370Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a sealing device, and particularly to a sealing device incorporated in a sealing portion between a cylinder member and a piston member of a piston mechanism.

(Prior art) In a piston mechanism as shown in Fig. 4, assuming that the left side in the figure is the hydraulic pressure side and the right side is the atmospheric pressure side, conventionally, in order to seal the gap between the cylinder member a and the piston member b, as shown below. structure is used. That is, c and d are annular grooves formed on the inner peripheral surface of the cylinder member a, and both annular grooves c and d
A pair of packings e and f are inserted and fitted inside. Of these, the packing e fitted in the annular groove c on the hydraulic side has a lip portion on its inner circumferential surface and is a seal ring e ₁ made of tetrafluoroethylene resin that seals and slides on the outer circumferential surface of the piston member b. and a tightening ring _e2 made of a rubber-like elastic material that is located on the bottom side of the annular groove and applies appropriate tight pressure to the seal ring _e1 , and a packing fitted in the annular groove d on the atmospheric pressure side. f is a C-ring _f1 made of a rubber-like elastic material with an annular concave portion facing the hydraulic pressure side, and a back-up spring _f2 made of a tetrafluoroethylene resin material disposed on the back surface of the C-ring _f1 in the axial direction. It consists of a combination of.

In the seal structure configured as described above, a primary seal portion is formed by the packing e located on the hydraulic side with respect to the fluid to be sealed that exists on the hydraulic side, and the fluid passing through the primary seal portion is On the other hand, the packing f on the atmospheric pressure side is configured to perform a secondary sealing action, but the tightening margin of the packing e on the hydraulic side with respect to the piston member b is when the piston mechanism is pressurized. (Fig. 4) and when the pressure is reduced (Fig. 5), it is always constant, so the fluid that has passed through the packing e on the hydraulic side is sealed by both packings e and f, so the fluid is The gas continued to accumulate in the annular space i between e and f, and the pressure in the space i gradually increased, eventually causing damage to each of the packings e and f. Also, the packing e on the hydraulic side is the piston member b.
Since the lip portion was in line contact with the outer peripheral surface, the stability was extremely poor.

The packing shown in FIGS. 6 and 7 was developed in view of these problems. This packing is fitted into an annular groove 3 formed on the opposing peripheral surface of one of the cylinder member 1 and piston member 2 that are fitted to each other, and is made of tetrafluoride which is in close contact with the other member. It has a seal ring 5 made of ethylene resin material, and a tightening ring 6 made of a rubber-like elastic material that fits into the seal ring 5 and applies close pressure, and the axial length of the seal ring 5 is fixed to the tightening ring 5. Formed longer than the axial length of the ring 6,
One axial end of the seal ring 5 on the sliding surface side is cut out to form a thinner part 5b than the other end, and the tightening ring 6 is pressed against the thin part 5b so that the seal ring 5 The contact width surface formed between the thin wall portions 5b and 5b is formed in the axial length of the thin wall portion 5b so that the contact width surface is in contact with the circumferential surface within the thin wall portion. The packing is done between the first seal part and the second seal part.
In the annular space 7 formed between the next seal parts, the first
Next, when the oil that has passed through the seal is accumulated and the pressure inside the annular space 7 becomes high, the seal ring 5 collapses as shown in FIG. Flow back to the hydraulic side, annular space 7
This reduces the internal pressure. After the back pressure is reduced, it will be restored to its original state. In this way, the tightening margin of the packing fitted into the annular groove on the hydraulic side is configured to change between pressurization and depressurization, and the first
This prevents pressure from accumulating between the secondary seal portion and the secondary seal portion.

(Problems to be Solved by the Invention) However, depending on variations in the dimensions of the tightening ring 6 and the dimensions of the notch of the seal ring 5, or depending on the pressure state or sliding state, the seal ring 5 may In some cases, the back pressure could not be reduced because the sealing ring e1 slid while lying down, causing the seal ring _e1 to protrude into the hydraulic pressure, resulting in malfunction of the piston member.

(Means for Solving the Problem) Therefore, the present invention has been developed to make it easier for the oil accumulated between the primary seal part and the secondary seal part to flow back to the hydraulic side. A groove extending from one axial end to the other axial end of the annular notch was formed in the annular notch.

(Function) As shown in Fig. 3, when the pressure of the oil accumulated between the primary seal part and the secondary seal part becomes high, the seal ring will fall down slightly, but the oil will move through the groove. The back pressure on the seal ring is reduced and the seal ring returns to its original normal position.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, and 3
is an annular groove formed on the inner peripheral surface of the cylinder member 1 into which the piston member 2 is inserted, and corresponds to the annular groove c on the hydraulic pressure side in FIG. 4 is inserted and fitted.
The packing 4 includes a seal ring 5 made of tetrafluoroethylene resin that seals and slides on the outer peripheral surface of the piston member 2, and a tightening ring made of a rubber-like elastic material that applies close pressure to the seal ring 5. 6 is combined, and the tightening ring 6 is formed to have a circular cross section and is pressed against the planar outer peripheral surface of the seal ring 5 with an appropriate contact width m. In addition, the seal ring 5 and the tightening ring 6 are formed so that the former seal ring 5 is longer in the axial length (width length), and the latter tightening ring 6 is formed so that the seal ring 5 It is possible to move freely on the top, that is, to change the relative position in the axial direction. On the other hand, since the seal ring 5 is also slightly shorter than the axial width of the annular groove 3, it moves in the axial direction due to pressure fluctuations (FIG. 2). The seal ring 5 has a tapered annular notch 5a formed on the inner circumferential surface of one end (approximately left half in the figure) on the hydraulic side, and the one end on the hydraulic side has the annular notch 5a. It is formed thinner than the other end (approximately the right half in the figure).
The thin wall portion 5b and the tightening ring 6 are configured such that the tightening ring 6 is in contact with the thin wall portion 5b of the seal ring 5 in the positional relationship when the pressure is reduced (FIG. 2). The length n from one end of the ring 6 (the left end in the figure) to the other end of the contact surface is shorter than the axial length i of the thin portion 5b. Further, the inner peripheral edge of the other end on the atmospheric pressure side of the seal ring 5 is chamfered 5c to prevent the end from protruding when pressurized.

The packing 4 having the above structure is inserted and fitted into the annular groove 3 on the hydraulic side of the two annular grooves formed on the inner circumferential surface of the cylinder member 1, as shown in FIG. It functions as a primary seal against the fluid to be sealed flowing in from the direction.
Packing having the same structure as that shown in FIG. 4 is fitted into each of the annular grooves on the atmospheric pressure side.

Now, when the inside of the container is pressurized to move the piston member 2 to the left in the figure (Fig. 1), high-pressure fluid passes through the gap between the cylinder member 1 and the piston member 2 and reaches the annular groove 3. The packing 4 is an annular groove 3
Since the tightening member 6 in the packing 4 moves on the seal ring 5, it is located on the outer periphery of the thick-walled other end of the seal ring 5. The main purpose of the tightening ring 6 is to apply close pressure to the seal ring 5, but the seal ring 5 itself also has a tightening allowance for the piston member 2, and furthermore, the tightening allowance is for the seal ring 5. 5 has a thin-walled portion 5b at one end, so each portion in the axial direction is different, that is, the thin-walled portion 5b is small and the thick-walled other end is large. Therefore,
When the tightening ring 6 is located on the outer periphery of the thick-walled other end of the seal ring 5 during pressurization, the tightening interference of the tightening ring 6, which is elastically deformed in the radial direction due to the pressure and has a relatively large value, causes the seal ring to tighten. 5, a large close pressure (clamping force) is obtained against the piston member 2, and a sealing effect similar to that of the conventional structure is achieved.

When the operating time of the piston mechanism has passed for a while and the sealed fluid leaks out of the primary seal by the packing 4, the leaked fluid flows through the packing 4 and another one placed on the atmospheric pressure side, as described above. The pressure accumulates in the annular space 7 between the packing f and the pressure gradually accumulates within the space 7. The piston mechanism repeatedly pressurizes and depressurizes the inside of the cylinder as it operates, and when the accumulated pressure in the annular space 7 exceeds the pressure in the cylinder member 1 during depressurization (low pressure), at that point In this case, the packing 4 is pushed by the accumulated pressure and moves toward the hydraulic pressure side within the annular groove 3, and the seal ring 5 moves by the width difference between the axial width of the annular groove 3 and the annular groove 3. However, the tightening ring 6 is further moved on the seal ring 5, and both rings 5 and 6 are pressed against the hydraulic side wall of the annular groove 3, and the tightening ring 6 is located on the outer periphery of the thin wall portion 5b of the seal ring 5. (Figure 2).
As described above, the close pressure (clamping force) obtained by the tightening margin of the thin wall portion 5b of the seal ring 5 and the clamping margin of the clamping ring 6 becomes small, and the seal ring 5 is compressed by the accumulated pressure in the annular space 7. Although it collapses slightly, the pressure fluid easily flows back to the hydraulic side through the groove 5d, and the pressure in the annular space 7 can be lowered. When the pressure within the annular space 7 is reduced, the seal ring is restored to its original position.

(Effect) Therefore, if the packing 4 having the above configuration is used, the leaked fluid that has conventionally continued to accumulate in the annular space 3 will be intermittently returned to the hydraulic pressure side, and the leakage fluid caused by the accumulation of pressure in the annular space 7 will be intermittently returned. Damage to each gasket can be prevented from occurring.

[Brief explanation of the drawing]

Figures 1 to 3 are cross-sectional views of a packing that is an embodiment of the present invention, Figures 4 and 5 are partial cross-sectional views of a piston mechanism showing how a conventional packing is used, and Figures 6 to 8. shows a cross-sectional view of conventional packing. 1...Cylinder member, 2...Piston member, 3
... Annular groove, 4 ... Packing, 5 ... Seal ring, 5a ... Annular notch, 5b ... Thin wall part, 5
c... Chamfered portion, 5d... Groove, 6... Tightening ring, 7... Annular space.

Claims (1)

[Scope of utility model registration request] It is a packing that is inserted into an annular groove 3 formed on the opposing peripheral surface of either the cylinder member 1 or the piston member 2 that are fitted to each other, and is made of a tetrafluoroethylene resin material that is in close contact with the other member. , and a tightening ring 6 made of a rubber-like elastic material that fits into the seal ring 5 and applies close pressure. one end of the seal ring 5 in the axial direction on the sliding surface side is notched to form a thinner wall portion 5b than the other end, and the tightening ring 6 is formed on the thin wall portion 5b side. The contact width surface formed between the pressed seal ring 5 and the seal ring 5 is brought into contact with the peripheral surface within the thin wall portion,
In the packing formed in the axial length of the thin part 5b, a groove 5d is provided in the annular notch 5a on the sliding surface side of the thin part 5b, extending from one axial end of the annular notch 5a to the other axial end. Packing characterized by the formation of.