JPH01295079A - Contactless mechanical seal - Google Patents

Abstract

PURPOSE:To uniformly obtain a clearance of a seal surface by forming the second sealing fluid-introducing groove between a stationary sealing ring and a retainer, in the case of a contactless mechanical seal introducing sealing fluid between a rotary sealing ring and the stationary sealing ring. CONSTITUTION:A casing 2 provides a stationary sealing ring 4 being opposed facing to a rotary sealing ring 3 fixedly provided in a rotary shaft 1. The stationary sealing ring 4 is urged in a direction of the rotary sealing ring 3 by a spring 9 through a retainer 5 from a back surface side. A sealing surface 3a is constituted between both the sealing rings 3, 4, and the first sealing fluid- introducing groove 11, loading a pressure of fluid to the sealing surface 3a, is formed. The second sealing fluid-introducing groove 12 is formed between the retainer 5 and the stationary sealing ring 4. By loading a pressure of fluid between the retainer 5 and the stationary sealing ring 4, the stationary sealing ring 4 is loaded in good balance from both sides, holding a clearance of a sealing surface 4a to a fixed value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a non-contact mechanical seal that is applied as a shaft sealing device for various fluid devices.

(Prior art) As this type of non-contact mechanical seal, for example,
What is shown in the figure is known. In figure 0, A is the axis of rotation (
On the rotating side), X indicates the inside of the machine (high pressure side), Y indicates the outside of the machine (low pressure side), and a rotating shaft A is rotatably provided in the center of the casing (fixed side) B. A non-contact mechanical seal is installed in the annular space between the casing B and the casing B.

This mechanical seal is held in a casing B in a movable and non-rotatable manner via a rotary sealing ring fixed to the rotary shaft A and a retainer E closely located on the back side, and is further rotatably sealed by a spring F. It has a stationary sealing ring G that is biased toward the ring side, and between the two G, a sealing surface d and g that is perpendicular to the axis is formed, and the inside of the machine X is sealed between these sealing surfaces 61g. The first one applies the sealed fluid pressure as a dynamic pressure.
It has a configuration in which a sealing fluid introduction group H is formed, that is, a spiral group is formed on the rotating sealing ring side.

(Problem to be Solved by the Invention) By the way, the non-contact mechanical seal has sealing surfaces d,
Since there is no friction between G and G, there is no damage to the seal due to wear on both rings and G, so the life of the seal is semi-permanent, and torque and power loss are negligibly small. Moreover, it has excellent properties such as being able to obtain high sealing performance. The high sealing performance is determined by the sealing fluid pressure and various dimensions of the sealing surface d.

This can be achieved by maintaining the size of the gap at a -like size across the radial direction. In order to maintain the gap between the seal surfaces d and g at a similar size in the radial direction,
It is required that the sealing surfaces d and g are flat, that is, that both the sealing surfaces d and g are perpendicular to the axis even if pressure distortion due to the sealed fluid pressure and thermal distortion due to the heat of the sealed fluid are affected. .

On the other hand, in non-contact mechanical seals, the rotating sealing ring is generally made of ultra-hard material such as ceramics, and the retainer E
is made of a hard material such as stainless steel, and the stationary sealing ring G is made of a relatively soft material whose main component is carbon. That is, the pressure strain and thermal strain characteristics of the three, E and G, are different. Moreover, in a configuration in which the retainer E and the stationary sealing ring G are in close contact with each other in the axial direction with different amounts of pressure strain and thermal strain, that is, in a configuration in which the retainer E is in close contact with the back surface of the stationary sealing ring G, the sealing fluid pressure is applied to the sealing surface g of the stationary sealing ring G and the flange portion e of the retainer E, causing both G
, E will be strongly pressed. Therefore, in the stationary sealing ring G, pressure strain is generated due to the biased sealing fluid pressure toward the retainer side, which is loaded on the sealing surface g, and the flatness of the sealing surface g is impaired. The biased sealing fluid pressure on the stationary sealing ring causes pressure strain with an amount of strain smaller than the amount of pressure strain on the stationary sealing ring G, and this pressure strain on the retainer E affects the stationary sealing ring G, causing the stationary sealing This further increases the amount of distortion in the ring G, and the flatness of the sealing surface g is greatly impaired. As a result, it becomes impossible to maintain the gap between the seal surfaces d1g at a -like size across the radial direction, which impairs the sealing performance, and in some cases, there is a risk that contact trouble may occur between the seal surfaces 61g.

In addition, thermal distortion occurs in the stationary sealing ring G and retainer E due to the heat of the sealed fluid. Similar to the pressure distortion described above, this thermal distortion also interferes with each other and has an adverse effect, impairing the flatness of the sealing surface g. become.

The present invention has been developed in view of the above circumstances, and is aimed at balancing the sealing fluid pressure with respect to the stationary sealing ring and retainer. In addition, even if pressure strain occurs in the soft static seal ring, this pressure strain and the thermal strain of both can adversely affect the static seal ring, and the flatness of the static seal ring seal surface can be ensured. The purpose of the present invention is to provide a non-contact type mechanical seal in which the gap between the sealing surface of a one-rotation sealing ring and the sealing surface of a stationary sealing ring is maintained at a uniform size in the radial direction, thereby achieving high sealing performance. do.

(Means for Solving the Problems) In order to achieve the above object, the present invention forms a first sealing fluid introduction group that forms a sealing surface with the one-rotation sealing ring and applies fluid pressure. A second sealing fluid introduction group is formed between the stationary sealing ring and the retainer located on the back side of the stationary sealing ring, which applies the fluid pressure to the stationary sealing ring as back pressure.

(Function) According to the present invention, since fluid can be introduced into the first and second sealing fluid introduction groups and fluid pressure can be applied in a well-balanced manner from both sides in the axial direction of the stationary seal ring, the stationary seal is sealed by pressure strain. The ring does not interfere with the retainer.

Furthermore, due to the fluid pressure introduced into the second sealed fluid introduction group, a gap is formed between the back surface of the stationary seal ring and the front surface of the retainer, and the fluid pressure can also be applied to the retainer from both sides in the axial direction in a well-balanced manner. Therefore, the retainer does not interfere with the stationary sealing ring due to pressure strain, and the flatness of the sealing surface of the stationary sealing ring is not impaired due to thermal strain due to fluid heat.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a half-cut sectional view showing an embodiment of the present invention, in which 1 is the rotation axis (rotation side), X is the inside of the machine (high pressure side), Y is the outside of the machine (low pressure side), A rotating shaft 1 is rotatably provided in the center of a casing 2, and a non-contact mechanical seal is installed in an annular space between the rotating shaft 1 and the casing 2.

This mechanical seal consists of a rotating sealing ring 3 and a stationary sealing ring 4.
The one-rotation sealing ring 3 having a retainer 5 and a retainer 5 is made of a super hard material such as a carbide single body, a carbide coating, or ceramics, and is fixed to the rotating shaft l so as to be rotatable at the same time. The O-ring 6 is brought into pressure contact with the outer periphery of the rotary shaft 1 in an annular groove formed on the inner periphery, thereby ensuring sealing between the two.

The stationary sealing ring 4 is formed of a soft material mainly composed of carbon, for example, and is fitted and held within the casing 2 so as to be able to move only axially. That is, on the back side of the stationary sealing ring 4, a retainer 5 made of a non-corrosive hard material such as stainless steel is arranged so as to be able to move only in the axis, and this retainer 5 and the stationary sealing ring 4 are arranged in a circle. The retainer 5 and the casing 2 are connected in a relatively non-rotatable manner by a plurality of detents 7 provided at equal intervals in the circumferential direction (however, only one detent 7 is shown in one drawing). is coupled to a plurality of detent pins 8 provided at equal intervals in the circumferential direction (however, only one detent pin 8 is shown in the drawing) in a relatively non-rotatable manner. Then, the stationary sealing ring 4 is inserted through the retainer 5 by the compression coil spring 9.
is urged toward the rotating sealing ring 3 side. Also, casing 2
By fitting the O-ring IO into the annular groove formed on the inner circumferential part of the retainer 5, and pressing this O-ring 10 into contact with the outer circumference of the cylindrical part 5A of the retainer 5, sealing performance between the two parts 2.5 is ensured. There is.

Seal surfaces 3a, 4a perpendicular to the axis C are formed between the rotating seal ring 3 and the stationary seal ring 4, and the seal surfaces 3a, 4a are perpendicular to the axis C.
A first sealing fluid introduction group 11 is formed between the first sealing fluid introduction group 11 and applying the sealing fluid pressure sealed inside the machine interior X as a dynamic pressure. That is, in this embodiment, the first sealing fluid introduction group 11 is as shown in FIGS. 2A and 2B.
It is composed of a plurality of spiral groups IIA formed on the sealing surface 3a of the rotary sealing ring 3.

Further, a second sealing fluid introduction group 12 is formed between the retainer 5 and the stationary sealing ring 4 to apply sealing fluid pressure to the stationary sealing ring 4 as back pressure. That is, in this example,
As shown in FIGS. 3A and 3B, the second sealing fluid introducing group 12 is formed with a deep annular groove 12A having a depth of 0.1 to 0.3 mm formed in the static seal ring side annular end surface 5B of the retainer 5. , a plurality of annular grooves 1 are formed at equal intervals in the circumferential direction.
2A to the outer periphery of the retainer 5 at a depth of 2 to 15 m
It is constituted by a shallow radial groove 12B. Note that 13 in FIG. 1 indicates a sleeve.

In the above configuration, when the rotating shaft l rotates and the rotating sealing ring 3 rotates together with it, the first sealing fluid introduction group 11 composed of the spiral group IIA formed on the sealing surface 3a of the rotating sealing ring 3 A fluid is introduced into the
Sealing surfaces 3a and 4B of the rotating sealing ring 3 and the stationary sealing ring 4
Dynamic pressure is applied between them, and this pressure keeps both parts 3.4 out of contact.

At the same time, fluid is introduced into the second sealing fluid introducing group 12 formed between the stationary sealing ring 4 and the retainer 5. That is, in order to configure the m2 sealing fluid introduction group 12,
Fluid is introduced into the deep annular groove 12A through the shallow radial groove 12B formed in the static seal ring side annular end surface 5B of the retainer 5, and static pressure is applied between the back surface of the static seal ring 4 and the front surface of the retainer 5. This pressure keeps both parts 4.5 out of contact.

And a flange portion 5C of the retainer 5 excluding the cylindrical portion 5A.
Since sealing fluid pressure is originally applied as static pressure to the rear surface of Loads will be applied from both sides.

Therefore, the perpendicularity of the sealing surface 4a of the stationary sealing ring 4 is not impaired, and as a result, the gap between the sealing surfaces 3a, 4a can be maintained at a size similar to that in the radial direction, so that the sealing fluid pressure introduced into this gap High sealing performance can be ensured. Furthermore, even if fluid pressure is applied to the soft static sealing ring 4 from both sides in the axial direction, pressure strain may occur that slightly reduces the axial dimension (thickness).
The perpendicularity of the sealing surface 4a is not impaired.

Further, the perpendicularity between the back surface of the stationary seal ring 4 and the annular end surface 5B of the stationary seal ring side of the retainer 5 is not impaired. Therefore, the gap between the back surface of the stationary seal ring 4 and the annular end surface 5B of the retainer 5 is Since the retainer 5 and the stationary sealing ring 4 can be held at a similar size across the gap, high sealing performance can be ensured by the sealing fluid pressure introduced into the gap, and the gap prevents the retainer 5 and the stationary sealing ring 4 from interfering with each other. Moreover, since no pressure strain occurs in the flange portion 5C of the retainer 4 except for the cylindrical portion 5A, the retainer 5 will not interfere with the stationary seal ring 4 and impair the flatness of the seal surface 4a of the stationary seal ring 4. Moreover, due to the heat of the sealed fluid, the stationary sealing ring 4 and the retainer 5 have different coefficients of thermal expansion.
Even if thermal strain occurs in
flatness can be maintained.

In the embodiment, the second sealing fluid introduction group 12 is
As shown in FIGS. 3A and 3B, there is a deep annular groove 12A formed on the front surface of the retainer 5, that is, on the stationary seal ring side annular end surface 5B, and a plurality of shallow radials that communicate the annular groove 12A with the outer periphery of the retainer 5. Although the explanation has been made with the grooves 12B, as shown in FIG.
A shallow circular groove 12 divided into a plurality of parts on the circumference by providing a
The second sealing fluid introduction group 12 may be configured by connecting the shallow radial grooves 12B to the second sealing fluid introducing group 12, respectively.

Furthermore, the first sealing fluid introduction group 11 is described as having a spiral group IIA formed on the sealing surface 3a of the rotary sealing ring 3 to apply dynamic pressure.
As shown in FIG. 6, on the sealing surface 4a of the stationary sealing ring 4,
A plurality of arc-shaped grooves 11B (however, only one arc-shaped groove 11B is shown in one drawing) is formed on the circumference, and a bypass 15 having an orifice throttle 14 is provided in each arc-shaped groove 11B. The first sealing fluid introduction group 11 may be formed such that the sealing fluid is introduced through the first sealing fluid introduction group 11.

(Effects of the Invention) As explained above, according to one aspect of the present invention, a stationary member forming a first sealing fluid introduction group that forms a sealing surface with a rotating sealing ring and applies fluid pressure to the rotating sealing ring. a sealing ring;
A second sealing fluid introduction group is formed between the retainers located on the back side of the stationary sealing ring to apply fluid pressure to the stationary sealing ring as back pressure. Since fluid can be introduced into each introduction group and fluid pressure can be applied in a well-balanced manner from both sides of the stationary seal ring in the axial direction, the flatness of the seal surface of the stationary seal ring with respect to the axis is not impaired, and the flatness of the rotary seal ring is The gap between the sealing surface and the sealing surface of the stationary sealing ring can be maintained at a similar size in the radial direction, and contact trouble between the two sealing surfaces can be reliably avoided and high sealing performance can be obtained. .

In addition, since well-balanced fluid pressure is applied to the stationary seal ring from both sides in the axial direction, even if this fluid pressure causes a pressure strain that slightly reduces the axial dimension (thickness) of the stationary seal ring. The flatness of the sealing surface is not impaired.

Furthermore, even if thermal distortion occurs in the stationary sealing ring and the retainer, which have different coefficients of thermal expansion due to fluid pressure, these thermal distortions do not interfere with each other, so the flatness of the sealing surface of the stationary sealing ring is maintained. It has the advantage of being able to obtain high sealing performance.

[Brief explanation of the drawing]

FIG. 1 is a half-cut sectional view showing one embodiment of the present invention. Figure 2A is an explanatory rear view showing a part of the sealing surface (% of circumference) of the rotary sealing ring, and Figure 2B is IIB-II of Figure 2A.
A sectional view taken along line B, FIG. 3A is an explanatory front view showing a part of the retainer (circumferential station), and FIG. 3B is mB-m in FIG. 3A.
A sectional view taken along line B, FIG. 4A is a pressure distribution diagram applied to the stationary sealing ring, FIG. 4B is a pressure distribution diagram applied to the retainer, and FIG. 5 is a groove forming the second sealing fluid introduction group. 6 is a schematic sectional view showing another embodiment of the first sealing fluid introduction group, and FIG. 7 is a half-cut sectional view of the conventional example. l...Rotating side (rotating shaft) 2... Fixed side (casing) 3... Rotating electrosealing ring 3a... Seal surface 4... Stationary sealing ring 4a... Seal surface 5... Retainer 9...Spring 11...First sealing fluid introduction group 12...Second
Group C for introducing sealing fluid... Axial center Patent applicant Nippon Pillar Industries Co., Ltd. Agent Patent attorney Takashi Suzue - 1st stage Figure 2A Figure 128 Figure IJ Figure 3A! Figure 33B” [B II 4A l l 4B Figure 115

Claims (1)

[Claims] (1) Equipped with a rotating sealing ring fixedly installed on the rotating side, and a stationary sealing ring that is held on the stationary side so as to be able to move axially through a retainer located on the back side, and is urged toward the rotating sealing ring by a spring. In a non-contact mechanical seal in which a sealing surface is formed between the two sealing rings and a first sealing fluid introduction group is formed to apply fluid pressure to this sealing surface, there is a sealing surface between the retainer and the stationary sealing ring. A non-contact mechanical seal characterized in that a second sealing fluid introduction group is formed for applying the fluid pressure to the stationary sealing ring as a back pressure.