JPH0718071U - Mechanical seal with bellows - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a mechanical seal provided with a bellows which suppresses self-excited vibration and resonance of the bellows. [Structure] O-ring 1 between bellows 1 on the outer peripheral side
0 is fitted and brought into contact with the compression ring 3 to suppress the displacement of the bellows 1.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 This invention relates to a mechanical seal provided with a bellows.

[0002]

[Prior art]

 A mechanical seal using a bellows instead of a packing such as an O ring is known as a seal between a driven ring and a rotary shaft or a casing. This type of mechanical seal has the advantage that the driven ring is not fixed by the O-ring or the like, and good floating of the driven ring can be maintained.

[0003]

[Problems to be solved by the device]

 However, in mechanical seals equipped with bellows, the bellows may generate self-excited vibration or resonance due to the resistance of the seal surface and the vibration of the attached equipment.These vibrations cause the seal surface to separate and cause leakage. However, there was a problem that the bellows itself was destroyed and a large amount of leakage occurred. Various studies have been made to solve such problems, but the mechanism of vibration generation is not clear and it is not possible to take drastic measures. For example, it is assumed that the above-mentioned vibration due to the resistance of the sealing surface is caused by the phenomenon of stick-slip, and the simple natural frequency calculation shows that the vibration generated by high-speed shaft rotation is extremely low at about 150 rpm. It is difficult to predict, such as occurring in the rotation range. The present invention aims to solve the above-mentioned problems of the prior art.

[0004]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a mechanical seal having a bellows for sealing a driven ring by a bellows, wherein a member having a displacement amount different from an axial displacement amount of the bellows and the bellows are provided. It is characterized in that the bellows are contacted so as to restrain the axial displacement of the bellows.

[0005]

[Action]

 The bellows is brought into contact with a member having a different displacement in the axial direction so as to restrain the axial displacement, whereby the axial displacement is restrained.

[0006]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a half sectional view. The driven ring 2 is loosely fitted onto the rotating shaft 50 so as to be driven, and a sealing surface S is formed between the driven ring 2 and the fixed ring 6 mounted on the casing 51 side for sealing. The compression ring 3 is fitted to the rear end side of the driven ring 2, and the compression ring 3 is pressed by the spring 5 in the direction of the fixed ring 6 so that the driven ring 2 is pressed against the fixed ring 6. There is. The rear end of the spring 5 is locked to the collar 4 fixed to the rotating shaft 50.

The bellows 1 is mounted inside the compression ring 3 at the rear end side of the driven ring 2, and the rear end thereof is fixed on the rotary shaft 50 by the collar 4. The bellows 1 seals between the driven ring 2 and the rotary shaft 50. An O-ring 10 is fitted in one of the fold groove portions 15 of the bellows 1, and the bellows 1 contacts the compression ring 3 via the O-ring 10 and is restrained.

In this embodiment, the O-ring 10 is attached to the fold groove portion 15 on the side of the collar 4 which is opposite to the driven ring 2 with respect to the center of the bellows 1. The reason for this will be described below. Assuming that the displacement amount of the driven ring 2 in the axial direction is d as shown in the figure, the compression ring 3 also has a displacement amount of d because it is fixed to the driven ring 2. Although the bellows 1 is also connected to the driven ring 2, the amount of displacement in the axial direction is larger at a position closer to the driven ring 2, and the displacement is absorbed and becomes smaller as the distance increases. That is, the displacement amount at the position a of the bellows 1 is almost the same as that of the driven ring 2 and becomes d, but at the position c, the displacement is almost absorbed and the displacement amount becomes almost zero. In addition, the amount of displacement is d / 2 at the middle position of a. Therefore, in order to bring the bellows 1 into contact with the compression ring 3 and restrain its movement in the axial direction, it is preferable to make contact in the vicinity of the position c where the difference in displacement is the largest. However, if the bellows 1 and the compression ring 3 are brought into contact with each other in the vicinity of the position c, on the contrary, the followability in the axial direction of the compression ring 3, that is, the driven ring 2, is impaired, and the contact resistance force of the O-ring 10 with the compression ring 3 is reduced. There is a problem that adjustment becomes difficult. Therefore, it is best to interpose the O-ring 10 at a position between A and C where the difference between the displacement amounts of the compression ring 3 and the bellows 1 is relatively large and the followability of the driven ring 2 is not restricted too much. It should be noted that the O-ring 10 must be larger in diameter than the interval f between the fold groove portions 15 of the bellows 1 and be locked in the fold groove portion 15 so as to come into contact with the compression ring 3 as shown in the figure.

In the above structure, the O-ring 10 interposed in the fold groove portion 15 of the bellows 1 comes into contact with the inner circumference of the comp ring 3, and the contact resistance regulates the axial displacement of the bellows 1. At the same time, radial vibration of the bellows 1 is also suppressed. Therefore, the self-excited vibration and resonance of the bellows 1 are suppressed, and the twisting force is buffered. Further, if the position of the O-ring 10 in the axial direction is set to an appropriate position between A and C, the followability of the driven ring 2 is not hindered and good sealing performance can be maintained.

Although the O-ring 10 is attached to the fold groove portion 15 of the bellows in the above embodiment, the present invention is not limited to this, and as shown in FIG. 11 may be provided and the O-ring 10 may be fixed thereto so that the bellows 1 and the O-ring 10 are in contact with each other. It is also possible to provide an O-ring groove 12 on the bellows 1 side as shown in FIG. 3 and fit the O-ring 10 therein.

FIG. 4 shows an embodiment in which the present invention is applied to a static mechanical seal in which the driven ring 2 does not rotate. In this configuration, since the compression ring 3 is located on the inner circumference side of the bellows 1, the O-ring 10 is provided on the inner circumference side of the bellows 1 and is in contact with the outer circumference of the compression ring 3. In addition, 20 is a sleeve.

[0012]

[Effect of device]

 As described above, the present invention provides a mechanical seal including a bellows for sealing a driven ring by a bellows, wherein a member having a displacement different from an axial displacement of the bellows and the bellows are provided. Since the contact is made so as to restrain the directional displacement, the axial displacement of the bellows is restrained, and the self-excited vibration and resonance of the bellows are suppressed.

[Brief description of drawings]

FIG. 1 is a half sectional view showing an embodiment of the present invention.

FIG. 2 is a partial half sectional view showing an embodiment of the present invention.

FIG. 3 is a partial judgment view showing an embodiment of the present invention.

FIG. 4 is a half sectional view showing another embodiment of the present invention.

[Explanation of symbols]

1: Bellows, 2: Driven ring, 3: Compring, 4: Color, 5: Spring, 6: Fixed ring, 10: O-ring,
11: O-ring groove, 12: O-ring groove, 15: fold groove portion, 20: sleeve, 50: rotating shaft, 51: casing.

Claims (4)

[Scope of utility model registration request] 1. A mechanical seal including a bellows for sealing a driven ring by a bellows, wherein a member having a displacement amount different from the displacement amount of the bellows in the axial direction and the bellows restrain the axial displacement of the bellows. Mechanical seal with a bellows characterized by being in contact with each other. 2. The mechanical seal provided with the bellows according to claim 1, wherein the bellows is brought into contact with the member via an O-ring. 3. The mechanical seal provided with the bellows according to claim 1, wherein the contact position is on the side of the driven ring opposite to the center of the bellows. 4. The mechanical seal provided with the bellows according to claim 1, 2 or 3, wherein the member is a member coupled to the driven ring.