JPS6215564Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to improvements in bellows seals.

Conventionally, bellows seals such as those shown in Figs. 1 and 2 have been known, but according to this type of prior art, the bellows seal shown in Fig. 1 is a bellows seal made of tetrafluoroethylene resin. A tapered wall c is formed at the front end b of the rotating side sealing ring d, and a tapered wall e is formed opposite to the tapered wall c on the rotating side sealing ring d, and the inclination angles of both the tapered walls c and e are made different. Therefore, the rotating side sealing ring d is pushed into the inner periphery of the front end b, and the bellows seal shown in FIG. The annular lip f is integrally molded, and the annular lip f is sandwiched between the adapter g and the rotating sealing ring d. According to these conventional techniques, the pressing force from the rotating sealing element to the sealing sliding surface i formed by the abutment surfaces of the rotating sealing ring d and the stationary sealing ring h is the front end of the bellows a. The pressing force of the coil spring k attached to the spring retainer j that is engaged in the axial direction with respect to part b in the axial direction forward (in the direction of the seal sliding surface i) and the seal enclosed in the inner periphery of the bellow a It is composed of the sum of the fluid pressure of the fluid and the elastic pushing force of the bellows a, but when the bellows a exceeds the free length, the elastic force of the bellows a is used as a reaction force, and the bellows As a expands and the reaction force gradually increases, the pressing force on the sealing sliding surface i (i.e., the surface pressure of the sealing sliding surface i) decreases, resulting in a decrease in sealing performance. It had drawbacks. Furthermore, as described above, these prior art techniques either force the rotation side sealing ring d into the inner periphery of the front end b of the bellows a (Fig. 1), or insert an annular lip f integrally formed on the end surface of the front end b. Since the adapter g and the rotary side sealing ring d are clamped under pressure to achieve a sealing effect at that part (Fig. 2), in the case of the former (Fig. 1), the sealed part is easily damaged and when reused. , the bellows a itself may have to be replaced, and even in the latter case (FIG. 2), the clamping pressure is concentrated on the annular lip f, making reuse difficult.

In view of the above points, the present invention has been developed by installing a sealing gasket and an adapter between the front end of the bellows made of Teflon tetrafluoride resin constituting the bellows seal and the rotating side sealing ring (insert) to seal this part. It is an object of the present invention to provide a bellows seal that solves the above-mentioned problems by applying the fluid pressure of the sealing fluid directly to the two, and separately transmitting the pressing force of a coil spring that constitutes the pressing force to the sealing sliding surface. It is something to do.

Hereinafter, one embodiment of the present invention will be described with reference to FIGS.
A bellow made of tetrafluoroethylene resin which is airtightly fixed to the outer ring thereof, the front end 1 of the bellow 1
b is pressed forward in the axial direction (to the right in the figure) by a coil spring 4 whose one end is fixed to the clamping ring 2, and is connected to the rotation axis via the clamping ring 2 and the knock pin 5. A spring retainer 6 to which the rotation of 3 is transmitted is engaged in the axial direction. The clamping ring 2 is divided into approximately two parts in the radial direction, and is tightened and fixed to the rotating shaft 3 by screwing with a hexagon socket head bolt 7. is a spring adapter. Reference numeral 9 in the figure is an insert having recesses 9a formed at appropriate locations on the outer periphery to fit into the protrusion at the tip of the spring retainer 6. The rotating shaft 3 is loosely fitted between the floating sheets 12 which are airtightly connected and fixed via the spring retainer 6, and the rotation of the rotating shaft 3 is transmitted by the uneven fitting with the spring retainer 6. The floating sheet 12 rotates together with the rotating shaft 3, and the contact surface with the floating sheet 12 forms a sealing sliding surface 13. Furthermore, an annular inner step 1c is formed on the inner periphery of the front end 1b of the bellows 1, while an annular outer step 9b is formed on the outer periphery of the rear end of the insert 9; In the annular cavity 14 formed between the annular outer step part 9b,
A sealing packing 15 having a V-shaped or U-shaped cross section and an adapter 16 are mounted in series in the axial direction so as to be sandwiched between opposing circumferential surfaces 1d and 9c, and are provided on the outer periphery of the rear end surface of the adapter 16. The annular projection 16a and the wall 1e of the inner annular step 1c are in contact with each other, and the front surface of the sealing packing 15 is in contact with the wall 9d of the outer annular step 9b.

The bellows seal of the present invention configured as described above prevents the sealing fluid sealed in the inner periphery from leaking to the outer periphery, and prevents the sealing sliding surface 13 from being pushed by the rotating sealing element. The pressure is applied to the spring retainer 6, the front end 1b of the bellows 1, the adapter 16,
The sum of the axially forward pushing force of the coil spring 4 transmitted sequentially through the sealing packing 15 and the insert 9, the fluid pressure of the sealing fluid directly applied to the rear end surface of the adapter 16, and the pressure of the bellows 1. It is composed of elastic pressing force, and the pressing force F is F=π/4(d ² ₁ - d ² ₂ )・P+Fp+W...(A
(Formula) d ₁ : Inner diameter of the annular protrusion 16a of the adapter 16 d ₂ : Inner diameter of the protrusion for the sealing sliding surface 13 of the insert 9 P: Fluid pressure Fp: Pushing force of the coil spring 4 W: Elastic pushing force of the bellows 1 The bellows seal of the present invention is characterized in that there is little variation in this pressing force F, and the sealing performance does not deteriorate significantly even if the bellows 1 exceeds the free length as in the above-mentioned conventional technology. be. That is, in the bellows seal of the present invention having the pressing force F shown by the above formula A, even if the bellows 1 is extended to exceed the free length and a reaction force W' directed rearward in the axial direction is generated, the fluid pressure P will not push the bellows 1. Directly ahead of the bellows 1 in the axial direction (i.e. near the sealing sliding surface 13)
Since the configuration is such that it acts on the rear end surface of the adapter 16 located at Pressure force due to P (F=
π/4(d ² ₁ −d ² ₂ )·P) can be always ensured as the minimum pressing force F. Furthermore, in the bellows 1, if the inner diameter d ₃ of the peak part of the bellows part 1f and the inner diameter d ₁ of the annular protrusion 16a of the adapter 16 are made approximately the same, the bellows 1 will maintain a stationary state in which all the fluid pressures acting in the axial direction are balanced. As a result, the axial pressing force F on the sealing sliding surface 13 can be stabilized, contributing to improved sealing performance.

Furthermore, in the bellows seal of the present invention, the sealing gasket 15 and the adapter 16 having a V-shaped or U-shaped cross section are installed between the front end 1b of the bellows 1 and the insert 9, so that the front end 1b of the bellows 1 and the insert 9 are attached. 9 can be sealed with a sealing packing 15, and at this time, the sealing packing 1
The adapter 16 is placed in the concave portion of the rear end surface of 5 with the above-mentioned pressing force F.
Since it is constantly press-fitted by the bellows 1 and the insert 9, the sealing performance in this part is not only excellent, but there is no risk of damaging the bellows 1 and the insert 9, and it is economical to only need to replace the sealing gasket 15 when reusing it. It is. Note that the height (length in the axial direction in the figure) of the annular protrusion 16a of the adapter 16 described above does not need to be particularly limited, and is set to 0.2 mm as an example.

As explained above, the bellows seal of the present invention is equipped with a sealing gasket and an adapter between the front end of the bellows made of Teflon tetrafluoride resin and the insert, and the fluid pressure of the sealing fluid is applied directly to both. In addition to transmitting the pressure of the coil spring, which separately constitutes the pressing force to the sealing sliding surface, the pressing force against the sealing sliding surface can be ensured at all times, which only improves the sealing performance. It is economical because the number of parts to be replaced during reuse can be reduced, and the practical effects of the present invention are extremely large.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIGS. 1 and 2 are half-cut cross-sectional views of the main parts of a conventional bellows seal, and FIG. 3 is a front cross-sectional view of the bellows seal of the present invention. Figure 4 is a half-cut sectional view of the same main part. 1... Bellows, 1a... Bellow rear end, 1b...
...Front end of bellows, 1c...Annular inner step, 1d...
Circumferential surface, 1e... Wall surface, 1f... Bellows part, 2... Clamping ring, 3... Rotating shaft, 4... Coil spring, 5... Knock pin, 6... Spring retainer, 7... Hexagonal hole Attachment bolt, 8... Spring adapter, 9... Insert, 9a... Recess, 9b... Annular outer step, 9c... Circumferential surface, 9d...
... Wall surface, 10 ... Housing, 11 ... Packing, 12 ... Floating sheet, 13 ... Sealing sliding surface, 14 ... Annular cavity, 15 ... Sealing packing, 16 ... Adapter, 16a ... Annular protrusion.

Claims (1)

[Claims for Utility Model Registration] (1) A bellow whose rear end is fixed to a rotating shaft; It consists of a spring retainer that presses forward in the direction, an insert that rotates with the rotation shaft via the spring retainer or the bellows, and a floating seat that is fixed to the flange of the housing and forms a sealed sliding surface with the insert. In the bellows seal, an annular inner step is formed on the inner periphery of the front end of the bellows, and an annular outer step facing the annular inner step is formed on the outer periphery of the insert. A sealing packing having a V-shaped or U-shaped cross section is interposed between the inner periphery of the front end portion and the outer periphery of the insert so that the front end surface is in contact with the wall surface of the annular outer step of the insert, and the sealing packing and An adapter is interposed so as to come into contact with the wall surface of the annular inner step of the bellows, and the adapter contacts the wall surface of the annular inner step of the bellows with an annular protrusion formed on the outer periphery of the rear end surface. A bellows seal characterized by its abutment. (2) The bellows seal according to claim 1, wherein the inner diameter of the annular projection is substantially the same as the inner diameter of the peak of the bellows portion.