JP2891900B2 - Non-contact type mechanical seal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type mechanical device which is preferably used in rotating equipment mainly dealing with gases (nitrogen, argon, hydrogen, natural gas, air, etc.) such as turbines, blowers, centrifugal compressors and the like. It is about a seal.

[0002]

2. Description of the Related Art As a conventional non-contact type mechanical seal of this kind, as shown in FIGS. 6 to 8, a rotary seal ring 3 fixed to a rotary shaft 2 and a rotary seal 2 are loosely fitted. A cylindrical holding portion 5a is formed in a circular holding hole 1c formed in the seal case 1 so as to be axially movably inserted and held in a state of being secondarily sealed via a first O-ring 7, and is formed at a front end portion thereof. A holding ring 5 having an L-shaped cross section and a spring 6 interposed between the seal case 1 and the pressing portion 5b of the holding ring 5, a rotary sealing ring 3, and a holding ring 5; And is loosely fitted to the rotating shaft 2, and the spring 6
The stationary sealing ring 4 is pressed and urged to the rotary sealing ring 3 via the holding ring 5 and the annular groove 11 formed on the front surface of the pressing portion 5b. A second O-ring 10 for maintaining a non-contact state of secondary sealing between the back face of the ring 4 and a sealing end face 3 a, which is an end face of the rotating sealing ring 3 and the stationary sealing ring 4. 4a, due to the relative rotation action and the action of the dynamic pressure generating groove 3b formed in one of the sealing end faces 3a, the sealing end faces 3a, 4
a to seal the first fluid region H, which is the outer peripheral region of the sealed end faces 3a, 4a, and the second fluid region L, which is the inner peripheral region, while keeping the a in a non-contact state (hereinafter, referred to as “the first fluid region H”). "Conventional seals" are well known.

The rotary seal ring 3, the stationary seal ring 4, and the holding ring 5 are made of different materials having different coefficients of thermal expansion and Young's modulus, respectively, due to their different functions. For example, the rotary seal ring 3 is made of an ultra-hard material such as WC or SiC, the stationary seal ring 4 is made of carbon or the like, which is softer than the components of the rotary seal ring 3, and the holding ring 5 is made of a metal material such as SUS304 or Ti. It is composed of On the other hand, the rotary seal ring 3, the stationary seal ring 4, and the holding ring 5 have thermal distortion and pressure distortion due to heat generated during operation and system pressure of equipment (hereinafter, these distortions are referred to as these distortions). However, these distortion amounts and distortion states are not the same, but differ from each other due to the difference in constituent materials. In particular, due to the constituent materials, the amount of distortion of the holding ring 5 is much larger than that of the rotating sealing ring 3 and the stationary sealing ring 4.

Therefore, when the stationary sealing ring 4 and the holding ring 5 are integrated by fitting or the like, their strains interfere with each other at the contact portions of the two rings 4 and 5, and the As a result, the stationary sealing ring 4 is strongly affected by the distortion of the retaining ring 5 and exhibits a completely different distortion state from its own distortion. For this reason, the smoothness of the stationary sealing end face 4a and the concentricity with the rotating sealing end face 3a,
If the degree of parallelism is impaired, the dynamic pressure generated between the sealing end faces 3a, 4a becomes non-uniform, and in extreme cases, unexpected situations such as poor dynamic pressure generation or local contact of the sealing end faces 3a, 4a may occur. This causes a problem that a good sealing function cannot be exhibited over a long period of time. In particular, such problems are high pressure,
This occurs significantly under high speed conditions, making it more difficult to use under such sealing conditions.

Therefore, in the conventional seal, as shown in FIGS. 6 and 7, a part of the second O-ring 10 protrudes from the annular groove 11 so that the back surface of the stationary sealing ring 4 and the holding ring 5 are formed.
A small clearance 12 is formed between the stationary sealing ring 4 and the front surface of the holding ring 5 so as not to be adversely affected by the distortion of the holding ring 5. That is, since the stationary sealing ring 4 and the holding ring 5 are only in indirect contact with each other via the second O-ring 10, different strains occur in the rings 4 and 5 due to pressure fluctuation, temperature change, and the like. In some cases,
These distortions are absorbed by the elastic deformation of the second O-ring 10 and do not interfere with each other, so that the stationary sealing ring 4 is not adversely affected by the distortion of the holding ring 5. As shown in FIGS. 6 to 8, the first O-ring 7 is provided between the inner peripheral surface of the holding hole 1 c of the seal case 1 and the outer peripheral surface of the held portion 5 a of the holding ring 5. Annular locking portions 9a, 9b provided on both sides
And is prevented from jumping out toward the first fluid region and the second fluid region.

[0006]

However, the conventional seal cannot be suitably used under conditions where the pressure relationship between the first fluid region H and the second fluid region L is reversed.
Applicable sealing conditions and equipment were greatly limited.

For example, when a conventional seal is used as a shaft sealing device for a gas turbine, during operation of the turbine, the pressure (turbine gas pressure) in the first fluid region H, which is an in-machine region, is increased when the turbine is operated. Although a positive pressure is applied higher than the pressure (atmospheric pressure) of the fluid region L, when the turbine is started, the in-machine region H becomes a negative pressure and a counter pressure is applied. When the pressure relationship between the two fluid regions H and L is reversed in this way, the pressure distribution acting on the stationary sealing ring 4 and the holding ring 5 is, as shown in FIGS. It differs greatly from when it works.

That is, when a positive pressure is applied, a pressing force F ₁ , which is a positive pressure (turbine gas pressure) having a pressure distribution as shown in FIG.
F ₂ acts on the front and back of the retaining ring 5, as shown in FIG.
The pressing forces F ₃ and F ₄ having the pressure distribution shown in FIG. Pressing force F ₁ is for acting on the sealing end surface 4a of the stationary seal ring 4, the sealing end faces 3a, is due to the dynamic pressure generated between 4a, the pressing force F ₂ is the back of the stationary seal ring 4 From the annular region facing the first fluid region H, that is, the portion corresponding to the outer peripheral surface of the sealed end face 4a.
This is due to the positive pressure acting on the annular area leading to the sealing location. The outer diameter of the stationary sealing ring 4 is the sealing end face 4a.
Is larger than the outer diameter of the outer peripheral side convex portion 4b.
The pressing forces F ′ ₁ and F ′ ₂ also act on the front and back surfaces of the, but since these pressing forces F ′ ₁ and F ′ ₂ are opposite in direction and have the same size and are offset, It is assumed that only the pressing forces F ₁ and F ₂ act on the stationary sealing ring 4.
Further, the pressing force F ₃ is a positive pressure acting on an annular region facing the first fluid region H on the front surface of the holding ring 5, that is, an annular region from the outer peripheral portion of the pressing portion 5 b to the sealing portion by the second O-ring 10. The pressing force F ₄ is a positive force acting on an annular area facing the first fluid area H on the back surface of the holding ring 5, that is, an annular area extending from the outer peripheral portion of the pressing portion 5 b to the sealing portion of the first O-ring 7. It is due to pressure.

On the other hand, when back pressure is applied, static sealing is required.
A pressure distribution as shown in FIG.
Pressure f due to reverse pressure₁, F_TwoActs on the retaining ring 5
Pressure distribution as shown in FIG.
Pressing force f due to back pressure_Three, F _FourWorks. Pressing force f₁
Acts on the sealing end face 4a of the stationary sealing ring 4.
And the back pressure acting between the sealing end faces 3a and 4a.
Yes, pressing force f_TwoIs the second on the back of the stationary sealing ring 4.
An annular area facing the fluid area L, that is, the inner circumference of the stationary sealing ring 4
From the point to the sealing point by the second O-ring 10
This is due to the back pressure acting on the area. Also, the pressing force f
_ThreeIs a ring facing the second fluid region L on the front surface of the holding ring 5.
The second O-ring 1
0 due to the back pressure acting on the annular area up to the sealing point
And the pressing force f_FourOn the back of the retaining ring 5
An annular area facing the second fluid area L, that is, the inner circumference of the retaining ring 5
Annular area from the point to the sealing point by the first O-ring 7
This is due to the back pressure acting on the area.

In this manner, the stationary sealing ring 4 and the holding ring 5
Use the specified sealing function under conditions where the pressure distribution used changes.
First of all, in order to exert it,
No contact between the sealed end faces 3a and 4a at any time
, That is, F ₁> F_TwoAnd f₁> F_TwoWhen
(Hereinafter referred to as "first condition")
You.

Therefore, the pressing force F_Two, F_TwoIs stationary seal ring 4
Axis of the annular area where positive and reverse pressures act on the back of the
Determined by the projected area on the orthogonal plane, that is, the pressure receiving area,
The pressure receiving area is determined by the area of the seal by the second O-ring 10.
Diameter (hereinafter referred to as “second seal diameter”) d₀More unique
And can be determined arbitrarily. Therefore,
Second seal diameter d₀Is set appropriately and the pressing force F_Two, F_Two
Is F₁> F_TwoAnd f₁> F_TwoBe configured so that
Can meet the first condition easily and specially
There is no difficulty. The second seal diameter d₀Is as described above
The second O-ring 10 seals (that is, the second O-ring 10).
(The contact point between the ring 10 and the stationary sealing ring 4).
However, such seal points are caused by thermal distortion and pressure of both rings 4 and 5.
Second by following relative displacement due to strain, vibration, etc.
It fluctuates due to deformation and displacement of the O-ring 10 and is uniquely determined.
Acting on the back of the stationary sealing ring 4
Distribution of positive and reverse pressures or pressing force F_Two, F_TwoIs the design
Upper, inner and outer diameters d of the annular groove 11₁, D_TwoIs the second seal diameter d₀
Is determined as The inside diameter d₁To F₁> F_TwoTona
So that the outer diameter d_TwoTo f₁> F_TwoSo that
If you specify₁<D ₀<D_TwoSo the second sea
Diameter d₀Fluctuates due to deformation and displacement of the second O-ring 10.
If the first condition is always satisfied
It is. In the non-contact type mechanical seal,
It is not planned that the pressure relationship between the two fluid regions H and L is reversed.
Inner and outer diameters d of the annular groove 11₁, D_TwoIs the
So that one condition is satisfied, that is, F₁> F_Twoabout
Is, of course, f₁> F_TwoAbout satisfy other conditions
As a result, it will inevitably be satisfied. For example, an annular groove
11 inner and outer diameter d₁, D_TwoIs smaller than the outer diameter of the sealing end face 4a.
If you do not make it much smaller, the pressing force F_TwoIs small
Too much, dynamic pressure F₁Inability to maintain balance with
Inevitably, if back pressure acts, f₁> F_TwoTona
You.

Second, either during positive pressure action or reverse pressure action
The secondary sealing function of the second O-ring 10 is
Needs to be fully demonstrated
Condition (F₁> F_TwoAnd f₁> F_TwoBefore satisfying
As a suggestion, F_Three<F_FourAnd f _Three<F_Four(Below
"Second condition") is required. In other words, positive pressure
In use, F₁> F_Two, F_Three<F_FourAnd back pressure action
At time f₁> F_Two, F_Three<F_FourIf it is
Then, the stationary sealing ring 4 and the retaining ring 5 are pressed in the approaching direction.
Then, the second O-ring 10 is pressed between both rings 4 and 5.
The second O-ring 10
This is because the next sealing function is sufficiently exhibited. On the other hand,
When the above conditions are not satisfied, the stationary sealing ring 4 is held.
The relative distance from the ring 5 is less than the elastic deformation limit of the second O-ring 10
Expanding upward, secondary sealing function by the second O-ring 10
Is reduced or in extreme cases, the second O-ring 10
The secondary sealing machine
This is because there is a possibility that the performance may be lost.

The pressing forces F ₃ , f ₃ and F ₄ , f ₄
Is determined by the projected area of the annular region on the front and back sides of the holding ring 5 where the positive pressure and the reverse pressure act on the plane orthogonal to the axis, that is, the pressure receiving area, and the pressure receiving area is the second seal diameter d _0.
And the diameter (hereinafter, referred to as “first seal diameter”) D ₀ of the sealing portion by the first O-ring 7, and can be uniquely and arbitrarily determined. By the way, the pressure distribution or the pressing force F due to the positive pressure and the reverse pressure acting on the front surface of the holding ring 5 is designed.
₃ and f ₃ are determined by taking into account the variation of the second seal diameter d ₀ due to the deformation and displacement of the second O-ring 10 as described above.
1 is determined based on the inner and outer diameters d ₁ and d ₂ (d ₁ <
When d ₀ <d ₂ ), the pressure distribution or the pressing force F ₄ , f ₄ due to the positive pressure and the reverse pressure acting on the back surface of the holding ring 5, the sealing position by the first O-ring 7 is always the position of the held portion 5 a. Since it is the outer peripheral surface and the contact point with the holding ring 5 does not fluctuate like the second O-ring 10, there is no need to consider such as the first seal diameter d ₀ and the outer diameter D _{1 of the} held portion 5a. Is determined based on the first seal diameter D ₀ (= D ₁ ) specified by

However, in the conventional seal, the first seal diameter D
_No matter how the relationship between ₀ and the second seal diameter d ₀ (that is, the relationship between the inner and outer diameters d ₁ and d _{2 of the} annular groove 11 and the outer diameter D ₁ of the held portion 5 a) is set, It is impossible to satisfy the second condition. That is, it is not possible to make the second seal diameter d ₀ larger or smaller than the first seal diameter D ₀ in a range satisfying the first condition (F ₁ > F ₂ , f ₁ > f ₂ ). , Any of which is possible,
d _0> D ₀ If (d ₁ ≧ D ₁₎ and to keep, F ₃ <F ₄ become even f _3> f _{4 becomes, d 0 <D 0 (d} 2 ≦ conversely
D ₁ ), F ₃ > F ₄ even if f ₃ <f ₄ . In fact, in the conventional seal, the inner diameter d ₁ of the annular groove 11 outer diameter D ₁ and the same or slightly larger to that of the held portion 5a (specifically, is set to d ₁ -D ₁ = 0 to 5 mm) for When a positive pressure is applied, F ₃ < F ₄ and a good sealing function is expected. When a reverse pressure is applied, f ₃ > f ₄ and a second O-ring 10 is obtained. The secondary sealing function is not sufficiently exhibited.

As described above, with the conventional seal, it is possible to achieve a configuration satisfying the first condition, but it is not possible to achieve a configuration satisfying the second condition. Therefore, the method cannot be applied to a condition or a device in which the pressure relationship between the first fluid region H and the second fluid region L is reversed.

The present invention has been made in view of such a point, and can be suitably used and applied even under conditions where the pressure relationship between the first fluid region and the second fluid region is reversed. An object of the present invention is to provide an extremely practical non-contact type mechanical seal in which sealing conditions and devices are not limited.

[0017]

SUMMARY OF THE INVENTION The present invention is directed to a rotary sealing ring fixed to a rotary shaft and an axially movable state in which a holding hole formed in a seal case is secondarily sealed via a first O-ring. A holding ring having a cylindrical held portion inserted and held therein and an annular pressing portion formed at the front end thereof, and a stationary sealing ring pressed and urged to the rotary sealing ring via the holding ring,
It is held in an annular groove formed on the front surface of the pressing portion,
A second O-ring for maintaining a secondary seal between the front surface of the pressing portion and the back surface of the stationary sealing ring in a non-contact state in which the secondary sealing is performed, and facing the rotating sealing ring and the stationary sealing ring. by rotating relative to the sealing end face, generated along with this
While held in a non-contact state between the seal end faces by dynamic pressure, non-contact, which is constituting the first fluid region that is the outer periphery region of the sealing end face and its inner a peripheral region second fluid region so as to seal In the mechanical seal, in order to achieve the above object, in particular, a space between the first fluid region and the second fluid region is provided.
A first O-ring to be secondary-sealed is formed between the inner peripheral surface of the holding hole and the outer peripheral surface of the portion to be held, which is opposed to the first O-ring. The first locking portion prevents the protrusion in the direction toward the stationary sealing ring, and the second locking portion provided on the seal case side prevents the projection in the direction away from the stationary sealing ring. Then, when the first fluid region is higher in pressure than the second fluid region, the first O-ring is pressed against the second locking portion by the fluid pressure of the first fluid region, and the pressure relationship between the two fluid regions is reversed. In such a case, the first O-ring is configured to be pressed against the first locking portion in reverse, so that the first fluid region and the
An annular groove for holding a second O-ring for secondary sealing between a two-fluid region and an inner diameter d ₁ and an outer diameter d _{2 of} the annular groove relative to the outer diameter D _{1 of the} held portion and the inner diameter D _{2 of the} holding hole. D ₁ ≧ D ₁
And it is proposed that d ₂ ≦ D ₂ .

[0018]

The pressure P in the first fluid region is larger than the pressure P in the second fluid region.
If (second fluid region pressure referenced to) is high, the pressing force F ₃ acting on the front surface of the retaining ring, pressure receiving area that is specified by an outer diameter D ₃ of the second sealing diameter d ₀ and a pressing portion 5b F ₃ = Pπ ((D ₃ ) ² − (d ₀ ) ² )) / 4
However, since the second seal diameter d ₀ varies within the range of the inner and outer diameters d ₁ and d ₂ of the annular groove holding the second O-ring, the variation (d ₁ <d ₀ <d ₂ ) is considered. Then, Pπ ((D
₃ ) ^2- (d ₂ ) ² ) / 4 <F ₃ <Pπ ((D ₃ ) ^2-
(D ₁ ) ² ) / 4. On the back surface of the retaining ring, the fluid in the first fluid region invades between the first locking portion and the first O-ring, and the inner peripheral surface of the first O-ring and the outer peripheral surface of the held portion are in contact with each other. The secondary seal will be performed at the contact point of. What
The first O-ring is similar to the conventional seal,
Pressed against the second locking part on the seal case side by the body
Will be. Accordingly, the pressing force F ₄ distribution or by which the pressure P in the back of the retaining ring is determined by the first sealing diameter D ₀ and an outer diameter D ₃ of the pressing portion, F ₄ = P
π ((D ₃ ) ² − (D ₀ ) ² ) / 4, where the sealing portion of the holding ring by the first O-ring is the outer peripheral surface of the held portion, and the first seal diameter D ₀ is Outside diameter D ₁
, F ₄ = Pπ ((D ₃ ) ² − (D
₁ ) ² ) / 4.

Further, if the pressure p of the second fluid region than the pressure of the first fluid region (a first fluid region pressure reference a) is high, the pressing force f ₃ acting on the front surface of the retaining ring, the second seal Given by the pressure receiving area specified by the diameter d ₀ and the inner diameter D _{4 of the} retaining ring, f ₃ = pπ ((d ₀ ) ² − (D ₄ ) ² )
/ 4, but the fluctuation of the second seal diameter d ₀ (d ₁ <d ₀ <
Considering d ₂ ), pπ ((d ₁ ) ² − (D ₄ ) ² )
/ 4 <f ₃ <pπ ((d ₂ ) ² − (D ₄ ) ² ) / 4. On the back side of the retaining ring, the second locking portion and the
Fluid in the second fluid region (pressure
The first O-ring is pressed against the first locking portion by p)
Will be. Then, since the first locking portion is provided on the holding ring side, the pressing force is applied to the holding ring to the stationary sealing ring.
To act as a force for pressing the. That is, the outer peripheral portion of the region where the pressure p acts is a contact portion between the outer peripheral surface of the first O-ring and the inner peripheral surface of the holding hole, and the distribution of the pressure p acting on the rear surface of the holding ring or the pressing force f ₄ due to this first seal diameter D ₀ is a factor that determines becomes the inner diameter D ₂ of the holding hole. Therefore, the pressing force f ₄ is given by the pressure receiving area specified by the inner diameter D _{2 of the} holding hole, which is the first seal diameter D _0, and the inner diameter D _{4 of the} holding ring, and f ₄ = pπ ((D ₀ ) ² −
(D ₄ ) ² ) / 4 = pπ ((D ₂ ) ² − (D ₄ ) ² ) /
It becomes 4.

Therefore, in the former case, d ₁ ≧ D ₁ and d ₂ > D ₁ , so that F ₃ −F ₄ <0 and F ₃ <F ₄ . On the other hand, in the latter case, d ₂ ≦ D ₂
Since d ₁ <D ₂ , f ₃ −f ₄ <0
And f ₃ <f ₄ . That is, d ₁ ≧ D ₁ , d
_By setting ₂ ≦ D ₂ , the second condition is always satisfied regardless of the pressure relationship between the first fluid region and the second fluid region.

On the other hand, the inner and outer diameters d of the annular groove₁, D_TwoTo
D₁, D_TwoSatisfies the first condition regardless of the relationship
The decision is easy, as mentioned at the outset.
Naturally, this is also done in the non-contact type mechanical seal.
It is that you are. Therefore, d ₁≧ D₁, D_Two≤D_Two
The first fluid region and the second fluid region
Conditions 1 and 2 are satisfied regardless of the pressure relationship
The structure can be made, always with stationary sealing ring and holding
The ring and the ring can be kept pressed against each other.
The secondary O-ring provides a good secondary sealing function.
Can be maintained.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of the present invention will be specifically described below with reference to the embodiments shown in FIGS.

This embodiment relates to an example in which the present invention is applied to a non-contact type mechanical seal for sealing a turbine shaft. As shown in FIG. 1, this non-contact type mechanical seal includes a seal case 1 and a seal case. An annular rotary seal ring 3 fixed to a rotary shaft 2 which is a turbine shaft penetrating the case 1, an annular stationary seal ring 4 axially opposed to the rotary seal ring 3 in the axial direction, and a stationary seal ring 4 A holding ring 5 held on the seal case 1 on the back side of the housing 1 and a plurality of coil-shaped springs 6 (only one is shown) interposed between the seal case 1 and the holding ring 5.

As shown in FIG. 1, the seal case 1 has a cylindrical guide wall 1a and a retainer wall 1b in which a circular holding hole 1c is formed.
And penetrate the retainer wall 1b concentrically.

The rotary seal ring 3 is made of a super-hard material such as WC or SiC. As shown in FIGS. 1 and 2, the end face 3a facing the stationary seal ring 4 in the axial direction has a spiral shape or the like. A dynamic pressure generating groove 3b having an appropriate shape is formed. By the action of the dynamic pressure generating groove 3b, a dynamic pressure is generated with the relative rotation of the sealing rings 3 and 4, and a fluid film is interposed between the sealing end faces 3a and 4a, which are the opposite end faces of the sealing rings 3 and 4. The formed non-contact state is maintained. Thus, in the portion where the fluid film is formed, the first fluid region H (that is, the high-pressure gas region inside the turbine of the turbine) that is the outer peripheral region of the sealed end faces 3a and 4a and the second fluid region that is the inner peripheral region thereof. A fluid region (that is, an atmospheric region outside the turbine) L is sealed.

The stationary sealing ring 4 is made of carbon or the like, which is relatively softer than the material of the rotating sealing ring 3, and as shown in FIGS. 1 and 2, extremely small guide walls 1a of the seal case 1 are formed. It is internally fitted and held movably in the axial direction with a gap. That is, an annular convex portion 4b and an annular concave portion 4c whose diameters are larger than the outer diameter and the inner diameter of the sealing end face 4a are formed on the outer peripheral portion and the inner peripheral portion on the back side of the stationary sealing ring 4, and the annular convex portion 4b is formed. For example, JIS-B0401
Guide wall 1a with a dimensional tolerance of about the clearance fit
To prevent the radial displacement of the stationary sealing ring 4 as much as possible between the outer peripheral surface of the annular convex portion 4b and the inner peripheral surface of the guide wall 1a. Is formed so as to allow an extremely small gap to be formed. Note that this gap is appropriately set in accordance with the diameter of the stationary sealing ring 4, sealing conditions, and the like.
It is preferable that the difference between the outer diameter of the annular projection 4b and the inner diameter of the guide wall 1a is set to about 10 to 100 μm.

The holding ring 5 is made of a metal material such as SUS304 or Ti. As shown in FIGS. 1 and 2, a cylindrical holding portion 5a and an annular pressing portion 5b formed at the front end thereof. And has an L-shaped cross section. As shown in FIG. 2, the holding ring 5 inserts and holds the held portion 5 a into the holding hole 1 c of the seal case 1 through the first O-ring 7 made of rubber, so that the space between the holding ring 5 and the seal case 1 is maintained. It is possible to move in the axial direction with the next sealed state.

As shown in FIG. 2, the first O-ring 7 is provided on the holding ring 5 side between the inner circumferential surface of the holding hole 1c and the outer circumferential surface of the cylindrical portion 5a opposed thereto. The first locking portion 8 prevents the protrusion in the direction of the first fluid region H, which is a direction toward the stationary sealing ring 4, and the second locking portion 9 provided on the seal case 1 side causes the stationary sealing ring 4 to move from the stationary sealing ring 4. Separation direction
The pop-out to the second fluid region L direction was prevented is,
It is loaded in a moderately compressed state. The first locking portion 8 is formed in an annular shape having an outer diameter slightly smaller than that of the holding hole 1c, and is integrally formed on the back side of the pressing portion 5b. The second locking portion 9, an inner diameter intended to form a slightly larger the annular than the outer diameter D ₁ of the held portion 5a, it is formed on the end portion of the holding hole 1c. In addition, the first O-ring 7 is mounted with an appropriate margin between the opposing surfaces of the locking portions 8 and 9 in the axial direction.

A concentric annular groove 11 is formed in the front surface 5d of the pressing portion 5b, and a rubber second O-ring 10 is fitted and held in this annular groove 11 with a slight protrusion. As shown in the figure, a secondary seal can be provided between the back surface 4d of the stationary sealing ring 4 and the front surface 5d of the holding ring 5 in a non-contact state having an appropriate clearance 12.

As shown in FIGS. 2 to 4, the annular groove 11 has a rectangular cross section, and its inner and outer diameters d ₁ and d ₂ are the outer diameter D ₁ of the held portion 5a and the holding hole. It is set so that d ₁ ≧ D ₁ and d ₂ ≦ D ₂ with respect to the inner diameter D _{2 of} 1c. The second O-ring 10 is of a size that can be appropriately held in the annular groove 10 as a matter of course.
In particular, a wire having a wire diameter (cross-sectional diameter in an undeformed state) equal to or smaller than the wire diameter of the first O-ring 7 is used.

By the way, as mentioned at the beginning,
During operation, positive pressure due to high-pressure gas in the first fluid area H acts
Also, when the turbine is started, the first fluid region H becomes negative pressure.
Back pressure acts on the front and back of the stationary sealing ring 4
FIG. 3A or FIG.
As shown in (A), the pressing force F due to the positive pressure₁, F_TwoOr vice versa
Pressing force f due to pressure₁, F_TwoWill work, but the ring
Inner and outer diameter d of the groove 11₁, D_TwoIs d₁≧ D₁, D_Two≤D
_TwoWithin the range of the first condition (F₁> F_Two, F₁> F _TwoFull)
It is set to help. Specifically, d₁To d₁≧
D₁F in the range ₁> F_TwoAnd set d_TwoTo d
_Two≤D_TwoF₁> F_TwoAnd set it to
Good. Pressing force F_Two, F_TwoIs actually the second O-ring 10
The diameter of the seal portion, ie, the second seal diameter d₀By
Is determined by d₁> D₀> D_TwoIs the inner and outer diameter
d₁, D_TwoIs set as above, the second O phosphorus
Seal diameter d due to deformation and displacement of₀Due to changes in
Not always, F₁> F_Two, F ₁> F_TwoBecomes The figure
As shown in FIG. 3 (A), the pressing force F₁Is the density of the stationary sealing ring 4.
Acting on the sealing end face 4a, and
a, and the pressing force F_TwoIs
An annular shape facing the first fluid region H on the back surface of the stationary sealing ring 4
From the region, that is, the location corresponding to the outer peripheral surface of the sealed end face 4a
Working in the annular area up to the seal location by the second O-ring 10
(Acting on the annular convex portion 4b)
Pressing force F '₁, F '_TwoAre offset). FIG.
As shown in FIG.₁Is the sealing of the stationary sealing ring 4
Acting on the end face 4a, the sealing end faces 3a, 4a
Due to the back pressure acting between_TwoIs still
An annular region facing the second fluid region L on the back surface of the sealing ring 4
Region, that is, the second O-ring 1
0 due to the back pressure acting on the annular area up to the sealing point
Things.

As shown in FIGS. 2 and 3, the front surface 5d of the pressing portion 5b is connected to the inner wall surface of the annular groove 11 and projects into the annular recess 4c of the stationary sealing ring 4 in a loosely fitting manner. An annular O-ring holding portion 5c protrudes. The O-ring holding portion 5c surely prevents the O-ring 10 from jumping out of the annular groove 11 in the radial direction or falling off, and the deformation and displacement of the O-ring 10 are prevented from being caused by the inner and outer diameters d of the annular groove 11.
Regulation is within _1, the range of d _2. Further, the annular concave portion 4c and O
The radial gap S between the ring holding portion 5c and the ring holding portion 5c is
Is set as small as possible without interfering with the relative displacement of the two rings 4 and 5 due to thermal distortion or the like (specifically, when both parts 4c and 5c are concentric, S =
It is preferably set to 0.3 to 0.5 mm).
Therefore, the relative eccentricity between the stationary sealing ring 4 and the holding ring 5 is restricted to a certain range by the engagement between the annular concave portion 4c and the O-ring holding portion 5c. Does not become significantly uneven.

As shown in FIG. 2, the retaining ring 5 has an appropriate number of detent pins (only one is shown) 13a to be implanted therein.
Is engaged with the retainer wall 1b of the seal case 1 so that the seal case 1 cannot be rotated relative to the seal case 1. The stationary sealing ring 4 is, as shown in FIG.
When a suitable number of locking pins (only one is shown) 13b implanted in the pressing portion 5b of the holding ring 5 are engaged with this, the relative rotation with respect to the holding ring 5 is disabled.
These detent pins 13a and 13b may be common. For example, one of the detent pins 13b is discarded, the other detent pin 13a is supported by the holding ring 5 in a penetrating manner, and both ends of the detent pin 13a are engaged with the retainer wall 1b and the stationary sealing ring 4 in a projecting manner. It may be.

Each of the springs 6 is interposed between the retainer wall 1b of the seal case 1 and the pressing portion 5b of the holding ring 5, as shown in FIGS. Urges in a direction toward the rotary seal ring 3 via the.

In the non-contact type mechanical seal configured as described above, the front and back surfaces of the holding ring 5 are shown in FIG.
4B or a positive pressure or a reverse pressure acts as shown in FIG. 4B, and the pressing forces F ₃ and F ₄ by the positive pressure and the pressing forces f ₃ and f ₄ by the reverse pressure are In each case, the second condition (F
₃ satisfies <F ₄ and f ₃ <f _4).

That is, when the positive pressure P acts, the pressing force F ₃ acts on the front surface of the holding ring 5, and this pressing force F ₃ is, as shown in FIG. In the annular region facing the first fluid region H, ie, the pressing portion 5b
This is due to the positive pressure P acting on the annular region from the outer peripheral portion to the sealing portion by the second O-ring 10. Accordingly, the pressing force F ₃ is provided by the pressure receiving area that is specified by an outer diameter D ₃ of the second sealing diameter d ₀ and a pressing portion _{5b (F 3 = Pπ ((} D 3) 2 - (d 0) 2 ) / 4) is Pπ ((D ₃ ) ² − (d ₂ ) ² ) / 4 <F ₃ <Pπ, considering the variation (d ₁ <d ₀ <d ₂ ) of the second seal diameter d _0.
((D ₃ ) ² − (d ₁ ) ² ) / 4.

On the back surface of the retaining ring 5, the fluid (turbine gas) in the first fluid region H enters between the first engaging portion 8 and the first O-ring 7, and Is secondarily sealed at the contact point between the inner peripheral surface of the base member and the outer peripheral surface of the held portion 5a. Accordingly, the pressing force F ₄ positive pressure distribution or which by the rear surface of the retaining ring 5 is determined by the outer diameter D ₃ of the first sealing diameter D ₀ and the pressing portion 5b, it is identified by these D _0, D ₃ (F ₄ = Pπ ((D ₃ ) ² − (D ₀ ) ² ) / 4) given by the pressure receiving area, the sealing position of the holding ring 5 with the first O-ring 7 is determined as described above. Outer peripheral surface, first seal diameter D
_{Since 0} is specified by an outer diameter D ₁ of the held portion 5a, F
₄ = Pπ ((D ₃ ) ² − (D ₁ ) ² ) / 4.

Therefore, Pπ (− (d ₂ ) ² +
(D ₁ ) ² +) / 4 <F ₃ −F ₄ <Pπ (− (d ₁ ) ²
+ (D ₁ ) ² ) / 4, but as described above, d ₁ ≧ D ₁
Since d ₂ > D ₁ , it is apparent that F ₃ −
F ₄ <0, and F ₃ <F ₄ .

On the other hand, when the back pressure p acts, the pressing force f ₃ acts on the front surface of the holding ring 5.
₃ is an annular region facing the second fluid region L on the front surface of the retaining ring 5, that is, an annular region extending from the inner peripheral portion of the retaining ring 5 to the sealing position by the second O-ring 10, as shown in FIG. This is due to the back pressure p acting. Therefore,
The pressing force f ₃ is determined based on the second seal diameter d ₀ and the inner diameter D _{4 of the} holding ring 5.
(F ₃ = p
π ((d ₀ ) ² − (D ₄ ) ² ) / 4) is pπ, considering the variation of the second seal diameter d ₀ (d ₁ <d ₀ <d ₂ ).
((D ₁ ) ² − (D ₄ ) ² ) / 4 <f ₃ <pπ
((D ₂ ) ² − (D ₄ ) ² ) / 4.

On the back side of the retaining ring 5, a reverse pressure
p is not only the rear end face of the held portion 5a, but also the first O-ring 7
Between the second O-ring 7 and the first O-ring 7
To the first locking portion 8. This pressing force is
Since the retaining portion 8 is provided on the retaining ring 5, the retaining ring 5
Acts as a pressing force. In other words, the area where the back pressure p acts
The outer peripheral portion of the region is located between the outer peripheral surface of the first O-ring 7 and
Acts as a contact point with the inner peripheral surface and acts on the back surface of the retaining ring 5
Distribution of the back pressure p or the resulting pressing force f_FourKey to determine
First seal diameter D₀Is the inner diameter D of the holding hole 1c._TwoTona
You. Therefore, the pressing force f_FourIs the first seal diameter D₀Barrel
Inner diameter D of holding hole 1c_TwoAnd inner diameter D of holding ring 5_FourAnd identified with
Given by the pressure receiving area_Four= Pπ ((D₀)
^Two− (D _Four)^Two) / 4 = pπ ((D_Two)^Two−
(D_Four)^Two) / 4.

Therefore, pπ ((d₁)^Two− (D_Two)
^Two) / 4 <f_Three−f_Four<Pπ ((d _Two)^Two−
(D_Two)^Two) / 4, but as described above, d_Two≤D_TwoWhen
And d ₁<D_TwoIs clearly f_Three−f
_Four<0 and f_Three<F_FourBecomes

As described above, the first condition (F ₁ > F ₂ and f ₁ > f ₂ ) that can be satisfied and naturally satisfied even in a general non-contact type mechanical seal is, of course, satisfied. In addition, since the second condition (F ₃ <F ₄ and f ₃ <f ₄ ), which has been considered to be structurally impossible with the conventional seal, can be satisfied, both in the case of the positive pressure action and the counter pressure action Also, the stationary sealing ring 4 and the holding ring 5 are held in a state where they are pressed against each other, so that the secondary sealing function of the second O-ring 10 is not reduced or lost.

The non-contact type mechanical seal according to the present invention is not limited to the above-described embodiment, but can be appropriately improved and changed without departing from the basic principle of the present invention.

For example, as shown in FIG. 5, the first locking portion 8 is formed as an annular body separate from the holding ring 5, and is disposed between the pressing portion 5a and the first O-ring 7 to be covered. You may make it fit and hold in the holding part 5a. In this case, the first locking portion 8
Does not need to be fixed to the holding ring 5 by an adhesive means or a shrink fitting means or the like, and in an extreme case, may simply be loosely fitted to the held part 5a so as to be movable in the axial direction. In short, the first locking portion 8 only needs to be able to prevent the first O-ring 7 from protruding from the holding hole 1c toward the first fluid region. The O-ring holding portion 5c protruding from the front surface of the holding ring 5 is
This is effective in reliably preventing the second O-ring 10 from protruding in the inner diameter direction and regulating the relative eccentricity between the stationary sealing ring 4 and the holding ring 5, but is particularly necessary depending on sealing conditions and the like. And not. Therefore, the present invention can naturally be applied to a non-contact type mechanical seal having no such O-ring holding portion 5c (for example, the same structure as the conventional seal shown in FIG. 6). Also,
The present invention provides a non-contact type mechanical seal (first fluid region H) for sealing conditions and applications in which the pressure relationship between the first fluid region H and the second fluid region L is passively reversed as in the above embodiment.
Is a fluid region to be sealed, and the second fluid region L is a non-sealed fluid region.
However, the present invention is not limited to such a non-contact type mechanical seal for sealing conditions and applications in which the pressure relationship between the two fluid regions H and L is positively reversed (for example, in a certain state, the first fluid region H is higher than the second fluid region L). High pressure, and in a certain state, the first fluid region H has a higher pressure than the second fluid region L, and both fluid regions H and L are normally sealed fluid regions. The present invention can be applied similarly to the above embodiment.

[0045]

As will be easily understood from the above description, according to the present invention, the pressure relationship between the first fluid region and the second fluid region is determined regardless of whether it is passive or positive. Even in the case of reverse rotation, a structure that satisfies not only the first condition but also the second condition can be obtained. Therefore, it can be suitably used for sealing conditions and applications that could not be used with conventional sealing, and it is possible to provide a highly practical non-contact type mechanical seal.

[Brief description of the drawings]

FIG. 1 is a half sectional vertical side view showing one embodiment of a non-contact type mechanical seal according to the present invention.

FIG. 2 is a longitudinal sectional side view showing a main part of FIG. 1 in an enlarged manner.

FIG. 3 is a distribution diagram of positive pressure acting on a stationary sealing ring and a holding ring of the mechanical seal.

FIG. 4 is a distribution diagram of a back pressure acting on a stationary sealing ring and a holding ring of the mechanical seal.

FIG. 5 is a longitudinal sectional side view showing a modification and corresponding to FIG. 2;

FIG. 6 is a longitudinal sectional side view corresponding to FIG. 1 showing a conventional seal.

FIG. 7 is a distribution diagram of positive pressure acting on a stationary sealing ring and a holding ring of the conventional seal.

FIG. 8 is a distribution diagram of a back pressure acting on a stationary sealing ring and a holding ring of the conventional seal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Seal case, 1c ... Holding hole, 2 ... Rotary shaft, 3 ... times
Rolling seal ring, 3a, 4a: sealing end face, 3b: dynamic pressure generating groove,
4: stationary seal ring, 4d: back of stationary seal ring, 5: holding
Ring, 5a: held portion, 5b: pressing portion, 5d: before pressing portion
Surface, 6 ... Spring, 7 ... First O-ring, 10 ... Second O
Ring, 11 ... annular groove, D₀… First seal diameter, D₁… Received
Outer diameter of holding part, D_Two... Inner diameter of holding hole, D_Three… Outside the pressing part
Diameter, D_Four... inside diameter of holding ring, H ... first fluid area, L ... second
Fluid region, d₀... second seal diameter, d ₁… Inner diameter of annular groove,
d_Two… The outer diameter of the annular groove.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16J 15/34

Claims (1)

(57) [Claims] 1. A rotary sealing ring fixed to a rotary shaft, and a cylindrical shape inserted and held in a holding hole formed in a seal case so as to be axially movable in a state of being secondarily sealed via a first O-ring. A holding ring having a held portion and an annular pressing portion formed at the front end thereof; a stationary sealing ring pressed and urged to a rotary sealing ring via the holding ring; A second O-ring held in the annular groove and holding a secondary seal between the front surface of the pressing portion and the back surface of the stationary sealing ring in a non-contact state, the rotating sealing ring and the stationary O-ring. by relative rotation of the seal end faces are opposite end faces of the sealing ring, the non between seal end faces by dynamic pressure generated in association with this
In the non-contact type mechanical seal configured to seal the first fluid region which is the outer peripheral region of the sealed end face and the second fluid region which is the inner peripheral region thereof while maintaining the contact state , the first fluid A first O-ring for secondary sealing between the region and the second fluid region is provided between the inner peripheral surface of the holding hole and the outer peripheral surface of the portion to be retained, which is provided on the retaining ring side. An annular first locking portion having a diameter slightly smaller than the holding hole prevents projection in the direction toward the stationary sealing ring, and a direction separating from the stationary sealing ring by a second locking portion provided on the seal case side. When the first fluid region is higher in pressure than the second fluid region, the first O-ring is pressed against the second locking portion by the fluid pressure in the first fluid region. When the pressure relationship between the two fluid regions is reversed In this case, the first O-ring is configured to be pressed in reverse to the first locking portion, and the annular groove for holding the second O-ring for secondary sealing between the first fluid region and the second fluid region is formed. The inner diameter d ₁ and the outer diameter d ₂ are set so that d ₁ ≧ D ₁ and d ₂ ≦ D ₂ with respect to the outer diameter D _{1 of the} held portion and the inner diameter D _{2 of the} holding hole. Non-contact type mechanical seal.