JPH0227732Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a bellows seal with a damping device related to non-contact shaft sealing technology.

[Conventional technology]

Conventionally, a floating ring airtightly supported on the housing side via a bellows is opposed to a seal ring airtightly mounted on the shaft side as a shaft sealing device, and there is a space between the seal ring and the floating ring. A non-contact bellows seal is used that allows sealing fluid to flow and seals the shaft while keeping them in a non-contact state, and as it has no sliding parts, it is useful as a wear-resistant, low-torque shaft sealing device.

[Problem that the invention attempts to solve]

However, in this type of bellows seal, the floating ring is supported by the bellows and is suspended in the fluid, so the spring constant of the bellows is K,
When the mass of the floating ring is M and the mass of the bellows is m, the natural frequency fo of the floating ring is fo = 1/2π√K/M+m/3, which is the same as or an integral multiple of the natural frequency fo. When vibrations with a period of 2 are input to the shaft sealing portion, the floating ring generates extremely large vibrations due to resonance, resulting in a problem that stable shaft sealing performance cannot be obtained.

It is an object of the present invention to provide a bellows seal with a damping device that can eliminate such a resonance phenomenon of the bellows seal and obtain a stable shaft sealing effect.

[Means for solving problems]

In other words, in the bellows seal with a damping device of the present invention, a floating ring facing the seal ring is supported and held from a direction perpendicular to the shaft via a damping device in order to suppress vibrations caused by resonance. A dart pot is provided, the piston is elastically neutralized within the dart pot, and a rod extending from the piston is brought into contact with the floating ring from the radial direction.
The oil is communicated through a communication pipe having an orifice, and the flow of oil filled in the dosspot is controlled and attenuated.

Further, the present invention has a structure in which the elastic pressing force by the coil spring can be adjusted, and the elastic supporting pressure in the radial direction on the floating seal can be adjusted.

[Effect]

In this way, the floating ring is supported floatingly by the spring force of the bellows and needle pot.
As mentioned above, it has a natural frequency of fo = 1/2π√K/M+m/3, but when it vibrates in the radial direction, the piston inside the dart pot slides through the rod of the dart pot, so it becomes narrower. Oil flows from the compartment side to the expanding compartment side via an orifice, and the flow-limiting action of the orifice damps vibrations of the piston and floating ring.

Further, by making the spring force of the dart pot variable, the damping speed can be adjusted.

〔Example〕

Hereinafter, embodiments of the bellows seal with a damping device of the present invention will be described with reference to the drawings. FIG. 1 shows the first embodiment. Code 1 is shaft 2
A floating ring 3 is inserted and fixed to the seal ring 1.
is loosely fitted onto the shaft 2 and supported on the housing 5 side via the bellows 4 to form a shaft seal. is allowed to flow slightly and maintained in a non-contact state with the floating ring 3. 7 is the above floating ring 3
The dart pot 7 is divided into an upper chamber A and a lower chamber B by a shaft 2 along an inner wall and a piston 8 that slides airtight in an orthogonal direction. At the same time, a rod 10 extending from the piston 8 protrudes in the direction of the floating ring 3 in an airtight manner, and its tip abuts against the outer periphery of the floating ring 3. The piston 8 also has a coil spring 11 elastically loaded in the upper chamber A side and a lower chamber B side.
It is elastically supported by a coil spring 12 elastically loaded on the side, and is configured such that the spring constant of the coil spring 11 on the upper chamber A side is larger than the spring constant of the coil spring 12 on the lower chamber B side. At the same time, the upper chamber A and the lower chamber B are communicated through a flow path 14 having an orifice 13 in the middle thereof, and are filled with oil 15.

In the bellows seal having the above structure, as the shaft 2 rotates, the sealing fluid is supplied between the seal ring 1 and the floating ring 3 by the pumping action of the fluid introduction groove 6, so that the two are maintained in a non-contact state. However, at the same time, since the floating ring 3 is supported by the bellows 4, it has a natural frequency. When added, resonance occurs.

However, according to the above configuration, since the rod 10 extending from the piston 8 of the dash pot 7 contacts the floating ring 3 from the outer diameter direction, the piston 8 is caused to slide due to the vibration, and the piston 8 is caused to slide. Since the oil 15 in the upper chamber A and lower chamber B, which are divided by
There is a delay in the return of the piston 8 due to the differential pressure between the two
This damps the vibration of the floating ring 3.

Next, FIG. 2 shows an embodiment of a bellows seal provided with a vibration damping force adjustment mechanism in the dart pot 7, and only the structure different from the above embodiment will be explained. A spring holder 16 presses the rear end of the coil spring 11 in the upper chamber A, and the spring holder 16 is brought into contact with the end of an adjusting screw 17 screwed into the dart pot 7 so as to be adjustable in the direction of the piston 8. That is, in this embodiment, both the coil springs 11, 1 of the upper chamber A and the lower chamber B are adjusted by moving the adjusting screw 17 forward and backward.
2 is compressed, and both coil springs 11, 1
Since the elastic stable position due to 2 changes, it exerts the effect of adjusting the damping force.

By providing three or more of the above-mentioned dart pots 7 at equal intervals in the circumferential direction, vibrations in all directions can be damped.

[Effect of idea]

As mentioned above, the bellows seal with a damping device of the present invention eliminates the resonance phenomenon by consuming vibration energy using the orifice resistance of the dart pot, resulting in stable sealing performance and a reliable shaft sealing effect. Therefore, the practicality of this invention is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view showing one embodiment of a bellows seal with a damping device of the present invention, and FIG. 2 is a front sectional view showing another embodiment of the damping device. 1... Seal ring, 2... Shaft, 3...
Floating ring, 4... Bellows, 7...
Dash pot, 8... Piston, 10... Rod, 11, 12... Coil spring, 13...
Orifice, 15...oil, 17...adjustment screw.

Claims (1)

[Claims for Utility Model Registration] (1) In a non-contact bellows seal in which a floating ring is opposed to a seal ring, the floating ring is divided into two chambers by a piston that is elastically and neutrally supported by a coil spring. A bellows seal with a damping device characterized in that a doss pot is partitioned and the two chambers communicate with each other via an orifice, and the doss pot is supported in the radial direction by a rod extending from the piston. (2) The bellows seal with a damping device according to claim 1, wherein the amount of compression of the coil spring is adjustable by an adjustment screw.