JP2513028Y2 - Non-contact type shaft seal device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is intended to improve a shaft sealing device that is mounted on a shaft sealing portion of a rotating device such as a pump or a compressor and has a sealing surface in a non-contact state. is there.

[Conventional technology]

Conventionally, as a non-contact type shaft sealing device, for example, as shown schematically in FIG.
Airtightly supported via coil spring
A fixed ring 104 that is axially biased by 103 is a rotating ring 107 that is airtightly supported on the outer circumference of a rotating shaft 105 via an O-ring 106.
To the one of the seal surfaces (the seal surface 107a of the rotary ring 107 in the illustrated example) that face each other in the axial direction and face each other,
It has a spiral groove 108 which is inclined at the end in the direction of drawing the fluid in the sealed space A on the outer peripheral side by the rotation, and the dynamic pressure effect of the spiral groove 108 causes a minute gap G to be present between the rings 104 and 107. A non-contact type mechanical seal which is held in a non-contact state is known.

[Problems to be solved by the device]

However, such a non-contact type mechanical seal has a seal surface on both sides thereof due to friction with the fluid in the gap G.
Since the 104a and 107a inevitably generate heat, the conventional structure has the following problems.

That is, due to the difference in thermal expansion due to the temperature gradient between the back surface 104b, 107b side and the seal surface 104a, 107a side serving as a heat source,
As shown in FIG. 6, thermal deformation occurs in both rings 104 and 107 such that the gap G becomes larger on the outer peripheral side which is the sealed space A side. If the portion of the gap G corresponding to the groove depth of the spiral groove 108 is g ₁ and the portion between the sealing surfaces 104a and 107a is g ₂ , the ratio (gap ratio g ₁ / g ₂ ) is the outer peripheral side. , The dynamic pressure effect of the spiral groove 108 is impaired and the gap G is narrowed, resulting in a further rise in temperature.
There was a risk that the 07a would come into contact and wear and damage. Further, not only the non-contact type shaft sealing device having the end face sealing structure such as the mechanical seal described above, but also the non-contact type shaft sealing device having the cylindrical face sealing structure which performs the shaft sealing function in the gap between the facing peripheral surfaces such as the floating ring seal. Had the same problem.

Therefore, in view of such a point, the present invention has an object to provide a non-contact type shaft seal structure in which the dynamic pressure effect is not impaired by thermal strain.

[Means for solving the problem]

In order to solve the above problems, the present invention provides a non-contact type shaft sealing device in which a non-rotating seal member and a rotating seal member face each other with a minute gap therebetween and seals between the facing surfaces. On one of the sealing surfaces facing each other of the member, there is a first-end spiral groove inclined in the direction of drawing the fluid from the sealed space into the gap at the time of rotation, and the groove depth of the spiral groove is set to In accordance with the amount of open deformation of the seal surfaces of both seal members due to frictional heat with the fluid, the depth is gradually increased toward the sealed space.

[Action]

According to the non-contact type shaft sealing device of the present invention, the groove depth of the spiral groove formed on one of the sealing surfaces causes the sealing surfaces of both sealing members to open due to frictional heat with the fluid present in the gap between the sealing members. Since the depth gradually increases toward the sealed space side according to the amount of separation deformation, the above-mentioned frictional heat is generated and the seal members are thermally deformed so that the gap between the seal surfaces is largely separated on the sealed space side. even, the gap ratio g ₁ / g ₂ between the groove depth g ₁ and the sealing surface between g ₂ of spiral grooves may be substantially constant over the sealed space side opposite to the sealed space side. Therefore the In the gap, a dynamic pressure and a static pressure that are large enough to bring the sealing surfaces into non-contact with each other can be obtained.

〔Example〕

FIG. 1 shows an embodiment in which the present invention is applied to a non-contact type mechanical seal.

In the figure, 4 is a fixed ring which is a non-rotating seal member which is airtightly supported on the housing 1 side via an O-ring 2 and is axially biased by a coil spring 3,
Is a rotary ring that is a seal member that faces the fixed ring 4 in the axial direction and that is supported by the outer periphery of the rotary shaft 5 in an airtight manner via an O-ring 6 and rotates.
As shown in FIG. 2, there is formed a spiral groove 8 which is slanted in the direction in which the fluid in the sealed space on the outer peripheral side is drawn by the rotation.

The spiral groove 8 is gradually deeper toward the outer peripheral side which is the sealed space A side, and the amount of change in the groove depth is due to friction with the fluid interposed in the gap G between the fixed ring 4 and the fixed ring 4. It is set according to the amount of opening deformation between the seal surfaces 4a, 7a of both rings 4, 7 due to heat. That is, as shown in FIG.
The fixed ring 4 and the rotary ring 7 have a large opening width on the outer peripheral side due to the difference in thermal expansion between the opposed seal surfaces 4a and 7a that generate a large amount of heat and the back surfaces 4b and 7b that do not generate much heat. Such thermal deformation occurs, but in this case, it corresponds to the amount of change from the opening width g _2a on the inner peripheral side between the sealing surfaces 4a, 7a to the opening width g _2b on the outer peripheral side, forming a blind alley. The amount of change is set from the groove depth g _1a at the inner peripheral end portion to the groove depth g _1b at the open end on the outer peripheral side.

In the above structure, when the rotary ring 7 rotates together with the rotary shaft 5, the spiral groove 8 formed in the seal surface 7a thereof.
Due to the pumping action of the
Since it is caught between 4 and 7, a dynamic pressure that separates the seal surfaces 4a and 7a is generated. In addition, as shown in FIG.
With respect to the static pressure distribution gradient p ₀ within the uniform gap G ₀ from the anti-sealing space B side (inner circumference) to the sealing space A side (outer circumference), as shown in FIG. Gap open to the side
Static pressure distribution gradient p ₁ in G ₁ is boosted by the amount indicated by oblique lines, thus in this embodiment the spiral grooves 8 are formed which gradually becomes deeper toward the sealed space A side from the same principle, a spiral groove The static pressure inside 8 is also large, and it is possible to maintain a non-contact state between both seal surfaces 4a and 7a.

Here, as the operating time elapses, the stationary ring 4 and the rotating ring 7
Is heated on the seal surfaces 4a, 7a side due to friction with the fluid interposed in the gap G between the two, and due to the difference in thermal expansion from the back surfaces 4b, 7b side, as shown in FIG. Of the spiral groove 8 from the groove depth g _1a to g _1b
Reaches variation in, since it is set corresponding to the leading amount of change in g _2b from separable width g _2a due to thermal deformation, in the thermal deformation state, the spiral groove groove depth g ₁ and the seal Face 4a, 7
The gap ratio g ₁ / g ₂ between a and g ₂ can be made substantially constant (g _1a / g _2a ≈g _1b / g _2b ) from the sealed space A side to the anti-sealed space B side, Therefore, the pressure distribution required to hold the seal surfaces 4a and 7a in a non-contact state is not impaired, and a stable function is achieved.

In this embodiment, the spiral groove 8 is provided on the seal surface 7a of the rotary ring 7, but the same effect can be obtained by providing the spiral groove 8 on the seal surface 4a of the fixed ring 4. Further, in addition to the non-contact type mechanical seal, a non-contact type shaft sealing device having a cylindrical surface sealing structure that performs a shaft sealing function in a gap between opposed peripheral surfaces, such as a floating ring seal, is provided with a cylindrical seal surface. Can be applied.

[Effect of device]

As described above, according to the present invention, even if the fixed and rotating seal members are thermally deformed by the frictional heat with the fluid so as to greatly separate the gap between the seal surfaces on the sealed space side, the gap ratio
Since g ₁ / g ₂ is almost constant from the sealed space side to the anti-sealed space side, the dynamic pressure that keeps the seal faces non-contact is not impaired, and the static pressure between the seal faces also increases. It is possible to maintain a stable function for a long time by reducing the gap between the seal surfaces due to thermal deformation, further increasing the amount of heat generation due to this, and preventing the occurrence of problems such as contact and damage of the seal surfaces.

[Brief description of drawings]

FIG. 1 is a schematic half-cut sectional view showing an embodiment in which the present invention is applied to a mechanical seal, FIG. 2 is a front view of the same main portion, and FIG. 3 is a half-cut sectional view showing a state in which thermal deformation similarly occurs. , FIG. 4 is an explanatory view showing a pressure distribution state between the seal surfaces,
FIG. 5 is a schematic half-cut sectional view showing an example of a conventional non-contact type shaft sealing device, and FIG. 6 is a half-cut sectional view showing a state where thermal deformation similarly occurs. 1 ... Housing, 4 ... Fixed ring (sealing member) 4a, 7a ... Sealing surface 7 ... Rotating ring (sealing member) 8 ... Spiral groove, A ... Sealed space G ... Gap

Claims (1)

(57) [Scope of utility model registration request] 1. A non-contact type shaft sealing device in which a non-rotating seal member and a rotating seal member are opposed to each other with a minute gap therebetween, and a shaft is sealed between the facing surfaces. One of the surfaces has a first-end spiral groove that is inclined in the direction that draws fluid from the sealed space into the gap during rotation, and the groove depth of this spiral groove slides with the fluid in the gap. A non-contact type shaft sealing device, which is gradually deepened toward the sealed space in correspondence with the amount of open deformation of the seal surfaces of both seal members due to heat.