JPS60222667A - Dynamic pressure type non-contact mechanical seal - Google Patents

Abstract

PURPOSE:To facilitate designing and calculating generated dynamic pressure by dividing a seal surface into a dynamic pressure generating area and a non-dynamic pressure generating area which have several grooves different in depth in a mechanical seal comprising a rotary seal ring and a fixed seal ring which are set opposite in contact with each other. CONSTITUTION:A mechanical seal comprises a rotary seal ring 9 fixed to the rotation side and a fixed seal ring (not shown) retained by a spring in such a manner as to move axially on fixed side which are set opposite in contact with each other. A seal surface 10 of the rotary seal ring 9 that is opposite in contact with the fixed seal ring is peripherally divided into a dynamic pressure generating area A and a non-dynamic pressure generating area B alternately. In this case, the area A is set narrower than the area B, and each area A is etched to form an equal number of grooves 11 having a comparative shallow depth with angle of advance. One deep groove 12 extending over the width of the area is similarly formed in each area B in such a manner as to have angle of advance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dynamic pressure non-contact mechanical seal that is often used as a shaft sealing device for rotating equipment, and more specifically, the present invention relates to a dynamic pressure non-contact mechanical seal that is often used as a shaft sealing device for rotating equipment. This invention relates to the improvement of Lucille's dynamic pressure type valve contact mechanism, which is mainly intended for shaft seal parts where dynamic pressure increases.

The typical configuration of this type of dynamic pressure type valve contact mechanical seal (hereinafter abbreviated as mechanical seal) is as shown in Fig. 3, in which the rotating shaft 2 is inserted into the casing l, and the right side of the figure is the low pressure side. , when the left side of the drawing is the high pressure side, the rotary shaft 2 is equipped with a rotary seal ring 3, and the casing 1 side is equipped with a backup ring 4 and a holding ring 5, and a fixed seal ring 6, so that both seal rings 3 ．．
The fixed seal ring 6 and the backup ring 4 are supported from the back by a bellows 7, with the seal ring 6 facing parallel to and in the same direction as the axis of the rotating shaft. In addition, the rotary seal ring 3 has a spiral groove (hereinafter referred to as a group) 8 on the sealing surface with the fixed seal ring 6, which changes the forward angle in the rotational direction of the rotary shaft 2. It is cut by cutting. The tip of this group 8 is opened to the high pressure side. In this mechanical seal structure, when the rotary shaft 2 rotates, fluid enters the group 8 having an advancing angle in the direction of rotation, causing the rotary seal ring 3 and the fixed seal ring 6
A dynamic pressure is generated between the two seals 1 and the bellows 7, and the balance between this pressure and the bellows 7 keeps both seals 1 tongues 3 and 6 out of contact.

By the way, the structure and shape of conventional mechanical seals were designed with emphasis on maximizing the dynamic pressure effect, which was preferable when dealing with low-viscosity fluids such as gas, but when dealing with high-viscosity fluids such as oil. When sealing a viscous fluid under high circumferential speed conditions, the dynamic pressure generated in group 8 becomes excessive, and the gap between the sealing surfaces of both seal rings 3.6 at the time of lancing increases, causing pressure to flow from the high pressure side to the low pressure side. The amount of leakage increases. In addition, due to excessive distortion of the sealing surface due to high dynamic pressure, there is an inconvenience that both seal rings 3.6 come into surface contact. It came to be devised.

That is, in FIG. 4, the length in the radial direction (depth) of group 8 is shortened, and in FIG. 5, the advance angle α of group 8 is shallowed.
In Fig. 6, the width d of group 8 is narrowed, and in Fig. 7, on the contrary, the area of group 8 is made extremely wide, in order to reduce the dynamic pressure. Further, FIG. 8 shows a combination structure in which shallow groups 8a and deep groups 9b are alternately provided.

However, according to the configurations shown in FIGS. 4 to 6, the cutting process for group 8 is complicated, and the difference between the theoretical value and the actual value of the generated dynamic pressure is large due to the decrease in machining accuracy, making design calculation difficult. At the same time, there is a problem of lack of reliability. Further, according to the configuration shown in FIG. 6, since the group width d is narrow, dynamic pressure cannot be generated due to the accumulation of slurry and abrasion powder, and the pressure distribution is complicated, making calculation of dynamic pressure difficult. Also, Figures 4 to 8
In any of the configurations shown in the figure, the sealing surface area is large, the amount of heat generated within the sealing surface is large, and the problem of distortion t± could not be solved.

Therefore, an object of the present invention is to provide a mechanical seal that is easy to process, allows easy design calculation of generated dynamic pressure, and has a structure that does not generate thermal strain.

That is, the present invention places a rotating seal ring and a stationary seal ring in contact with each other, and uses the dynamic pressure generated by the dynamic pressure generation group to seal the two rings while keeping them in a non-contact state. It is divided into a dynamic pressure generation area and a non-dynamic pressure generation area in the circumferential direction, and in the dynamic pressure generation area, a group with a shallow groove depth is formed, and in the non-dynamic pressure generation area, a group with a deep groove depth is formed. It is characterized by forming a group with a

According to the present invention, in the dynamic pressure generating region, remarkable dynamic pressure is generated due to the shallow groups, and in the non-dynamic pressure generating region, the generated dynamic pressure disappears due to the deep groups.

In this way, the area where dynamic pressure is generated is limited to a few narrow areas on the circumferential direction of the seal surface, and the boundaries between areas where no dynamic pressure is generated are clearly distinguished, so that the pressure distribution during one rotation is accurate. can be estimated, thus allowing accurate design calculations.

Moreover, since the length of the group in the dynamic pressure generation area, the advance angle α, and the radius d are not modified, it is easy to cut the group, and the machining accuracy is high. Can be estimated.

Further, since the dynamic pressure generation area is limited (narrow), even if the dynamic pressure generated in the area is large, the opening force on the sealing surface can be small.

Therefore, it becomes easier to balance the pressure at equilibrium, and the gap between the sealing surfaces can be narrowed, making it possible to design a sealing structure with less leakage.

Furthermore, by making the glu nib groove deep in the non-dynamic pressure generation area, heat generation due to viscous shear of the fluid between the seal surfaces can be suppressed, and thermal distortion of the seal surface can be suppressed to a small level.

At the same time, the amount of sealing liquid circulating in the area increases, improving the cooling effect of the sealing part.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

In the rotary seal ring 9, the seal surface 10 that is in contact with the fixed seal ring 6 is divided into a dynamic pressure generating area A and a non-dynamic pressure generating area B alternately in the circumferential direction. As is clear from FIG. 1, the dynamic pressure generating area A is narrower than the non-dynamic pressure generating area B, and each dynamic pressure generating area A has the same area width, so each non-dynamic pressure generating area B also have equal region widths.

In each dynamic pressure generation area A, an equal number of groups 11 have a relatively shallow groove depth and an advancing angle similar to those conventionally cut under low viscosity liquid and low circumferential speed conditions. On the other hand, in each non-dynamic pressure generating region B, a group 12 having one deep groove depth over the width of the region is also machined with an advancing angle. The other surfaces are conventionally flat surfaces, and the sealing surface of the fixed seal ring 6 is also flat.

In the mechanical seal having such a group structure, high dynamic pressure is generated in the dynamic pressure generation area A due to the group 11 having a shallow groove depth, but in the non-dynamic pressure generation area B, the group 12 is generated. Because the groove depth is deep, almost no dynamic pressure is generated.Therefore, the sealing surface gap between the rotating seal ring 9 and the stationary seal ring 6 is in the dynamic pressure generation area A.
The dynamic pressure generated in the dynamic pressure generation area A is determined by the pressure balance between the generated dynamic pressure and the bellows 7. However, due to the high viscosity fluid such as oil and high circumferential speed, the generated dynamic pressure in the dynamic pressure generation area A is at most 1. Since the area A is limited to a few places in the circumferential direction of the seal surface, the total dynamic pressure generated is lower than that of the conventional type, which generates dynamic pressure around the entire circumference of the seal surface lO, and therefore the seal The surface gap can be kept narrow.

Furthermore, if the non-dynamic pressure generating region B is provided and the groove of the core group 12 is made deep, the sealing surface area between the rotary seal ring 9 and the stationary seal ring 6 is substantially reduced by the region (B). Therefore, the area of the heat generating surface can be reduced. Moreover,
As a large amount of fluid flows into and out of the group 12 as it rotates, heat generated at the sealing surface is removed, cooling is effectively performed, and thermal distortion is suppressed.

The optimal values for the number of dynamic pressure generating parts A and the ratio of regions A and B change depending on the sealing conditions.The higher the viscosity and the higher the circumferential speed, the smaller the ratio of region A needs to be. Since the region A where generation occurs and the region B where it does not occur are clearly distinguished, the design calculation of the generated dynamic pressure is easy and the difference from the actual value can be eliminated, which is practical.

Although a spiral group is used in the drawings for the dynamic pressure generating region A, a known Rayleigh step shape may be used.

The material of the sealing surface IO needs to be a hard material in terms of wear resistance in the parts to be group-processed, but a soft material such as carbon can be used in the flat parts.

Furthermore, in the above embodiment description, the dynamic pressure generating portion A was formed on the outer diameter side of the seal ring 9, and the seal portion was formed on the inner diameter side.
Depending on the sealing conditions, these relationships may be reversed.

Furthermore, the present invention can be used in addition to high viscosity liquid and high peripheral speed conditions.

Of course, it can also be used under conditions of medium viscosity liquid and medium circumferential speed.

[Brief explanation of the drawing]

1 and 2 show one embodiment of the present invention, FIG. 1 is a front view of a rotary seal ring, and FIG. 2 is an II of FIG. 1.
-II line arrow sectional view. Figure 3 is a cross-sectional view for explaining the dynamic pressure type non-contact mechanical seal structure, and Figures 4 to 8 show the main points of the sealing surface, respectively, showing conventional measures for generating dynamic pressure against high viscosity liquid and high circumferential speed conditions. FIG. l... Casing (fixed side) 2... Rotating shaft (rotating side) 6... Fixed seal ring 7... Bellows 9... Rotating seal ring 11... Shallow groove depth group 12. ...Deep groove depth Group A...Dynamic pressure generating area B...Non-dynamic pressure generating area Patent applicant Nippon Pillar Industries Co., Ltd. Agent Patent attorney Takashi Suzue - Figure 1 Figure 2 Figure 4 Figure 5 Figure 8 Procedural Amendment 4th Director of the Japan Patent Office Kazuo Wakasugi1, Indication Patent Application No. 1988-808822, Title of Invention Dynamic Pressure Type Valve Contact Mechanical Seal Nippon Biller Kogyo Co., Ltd. - Voluntary 6 , Description and Drawing 7 to be amended Contents of amendment As shown in the attached sheet (1) The entire text of the description is amended as shown in the attached sheet. (2) In the drawings, Figure 8 is amended as shown in the attached sheet. Above □, ″ Description 11 Name of the invention Dynamic pressure type valve contact mechanical seal 2, Claims (1) A rotary seal ring fixed on the rotating side and a fixed member held movable in the axial direction via a spring on the stationary side. In a seal ring that faces the seal ring and forms a dynamic pressure generating group (groove) having an advancing angle on the sealing surface, the sealing surface is arranged alternately in the circumferential direction with a dynamic pressure generating area and a non-dynamic pressure generating area. A dynamic pressure type valve that is divided into two regions, and forms a group with a shallow groove depth in the dynamic pressure generation area, and a group with a deep groove depth in the non-dynamic pressure generation area. Contact mechanical seal. 3. Detailed description of the invention The present invention relates to a dynamic pressure non-contact mechanical seal that is often used as a shaft sealing device for rotating equipment. This invention relates to the improvement of dynamic pressure type valve contact mechanical seals that are mainly targeted at shaft seal parts where the dynamic pressure generated is large. The composition is the third
As shown in the figure, when the rotating shaft 2 is inserted into the casing l and the right side of the figure is the low pressure side and the left side of the figure is the high pressure side,
The rotary shaft 2 is equipped with a rotary seal ring 3, and the flange and flange 5 fixed to the casing L side are equipped with a fixed seal ring 6 via a backup ring 4, so that both seal rings 3°6 are aligned in the axial direction of the rotary shaft. A fixed seal ring 6 and a backup ring 4 are supported from the back by a spring 7 so as to face each other in parallel and the same direction. In addition, the rotary seal ring 3 has a spiral groove (J, tT, 2.-7
It is machined with an advancing angle of □, 871.12°, and □1. The tip of this group 8 is opened to the high pressure side. In this mechanical seal structure, −
When the rotating shaft 2 rotates, fluid enters the group 8 having an advance angle in the direction of rotation, generating dynamic pressure between the rotating seal ring 3 and the stationary seal ring 6, and the interaction between this pressure and the spring 7. Depending on the pressure balance, both seal rings 3 and 6
is kept in a contactless state. By the way, the structure and shape of conventional mechanical seals were designed with emphasis on maximizing the dynamic pressure effect, which was preferable when dealing with low-viscosity fluids such as gas, but when dealing with high-viscosity fluids such as oil. When sealing a viscous fluid under high circumferential speed conditions, the dynamic pressure generated in group 8 becomes excessive, and the gap between the sealing surfaces of both seal rings 3 and 6 during the above balance increases, causing leakage from the high pressure side to the low pressure side. The amount increases. In addition, due to excessive distortion of the sealing surface due to high dynamic pressure, there is an inconvenience that both seal rings 3.6 come into surface contact, and various measures have been taken to solve this problem, as shown in the configurations shown in Figures 4 to M47. It came to be devised. That is, in FIG. 4, the length in the radial direction (depth) of group 8 is shortened, and in FIG. 5, the advance angle α of group 8 is made shallow,
In FIG. 6, the width d of group 8 is narrowed, and in FIG. 7, on the contrary, the area of group 8 is made extremely wide, in order to reduce the dynamic pressure. However, according to the configurations shown in FIGS. 4 to 7, the influence of machining errors in group 8 is large and complicated, and the difference between the theoretical value and the actual value of the generated dynamic pressure is large due to a decrease in machining accuracy.
It is difficult to perform design calculations and is unreliable. Further, according to the configuration shown in FIG. 6, since the group width d is narrow, there are disadvantages in that slurry and abrasion particles accumulate and no dynamic pressure is generated, and the pressure distribution is complicated, making calculation of the dynamic pressure difficult. Further, in any of the configurations shown in FIGS. 4 to 7, the sealing surface area was large, the amount of heat generated within the sealing surface was large, and the problem of distortion could not be solved. Therefore, an object of the present invention is to provide a mechanical seal having a structure that is easy to process, allows easy theoretical calculation of generated dynamic pressure, and has a structure with minimal thermal distortion. The fixed seal ring is placed in contact with the ring, and the dynamic pressure generated by the dynamic pressure generation group is used to make both rings non-contact.
In order to seal while maintaining the condition, the seal surface is divided alternately and circumferentially into a dynamic pressure generation area and a valve operating pressure generation area, and a group with a shallow groove depth is formed in the dynamic pressure generation area. However, in the region where no dynamic pressure is generated, a group having a deep groove depth is formed. According to the present invention, in the dynamic pressure generating region, remarkable dynamic pressure is generated due to the shallow groups, and in the non-dynamic pressure generating region, the generated dynamic pressure disappears due to the deep groups. In this way, the area where dynamic pressure is generated is limited to a few narrow areas on the circumferential direction of the seal surface, and the boundaries between areas where no dynamic pressure is generated are clearly distinguished, so the pressure distribution during rotation can be accurately estimated. Therefore, accurate theoretical calculations can be made in advance. Moreover, since the length, advance angle α, and width d of the group in the dynamic pressure generation area are not modified, the group is easy to process, the machining accuracy is high, and the estimation of the generated dynamic pressure will continue to be even more accurate. I can do it. Furthermore, since the dynamic pressure generation area is limited (narrow), even if the dynamic pressure generated in the area is large, the opening force on the entire sealing surface can be made small. Therefore, it becomes easier to balance the pressure at equilibrium, and the gap between the seal surfaces can be narrowed, resulting in a seal structure with less liquid leakage. Furthermore, by making the group grooves deep in the non-dynamic pressure generating region, it is possible to suppress heat generation due to viscous shear of the fluid between the seal surfaces, and it is possible to suppress thermal distortion of the seal surfaces to a small level. At the same time, the amount of sealing liquid circulating in the area increases, improving the cooling effect of the sealing part. An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. In the rotary seal ring 9, the seal surface 10 that is in contact with the fixed seal ring 6 is divided into a dynamic pressure generating area A and a non-dynamic pressure generating area B alternately in the circumferential direction. As is clear from FIG. 1, the dynamic pressure generating area A is narrower than the non-dynamic pressure generating area B, and each dynamic pressure generating area A has the same area width, so each non-dynamic pressure generating area B also have equal region widths. 4. In each dynamic pressure generation area A, an equal number of groups 11 are etched with a relatively shallow depth and an advancing angle, which is almost the same as that conventionally processed under low viscosity and low circumferential speed conditions. On the other hand, in each non-dynamic pressure generating region B, a group 12 having one deep groove depth over the width of the region is also machined with an advancing angle. The other surfaces are conventionally flat surfaces, and the sealing surface of the fixed seal ring 6 is also flat. In the mechanical seal having such a group structure, high dynamic pressure is generated in the dynamic pressure generation area A due to the group 11 having a shallow groove depth, but in the non-dynamic pressure generation area B, the group 12 is generated. Because the groove depth is deep, almost no dynamic pressure is generated.Therefore, the sealing surface gap between the rotating seal ring 9 and the stationary seal ring 6 is in the dynamic pressure generation area A.
It is determined by the pressure balance between the generated dynamic pressure and the spring 7. Therefore, even if the dynamic pressure generated in the dynamic pressure generation area A is high due to high viscosity fluid such as oil and high circumferential speed, the area A is limited to a few locations in the circumferential direction of the seal surface. Therefore, the total dynamic pressure generated is lower than that of the conventional type in which dynamic pressure is generated around the entire circumference of the sealing surface lO, and therefore the sealing surface gap can be kept narrow. Furthermore, if the non-dynamic pressure generating region B is provided and the groove of the chain group 12 is made deep, the sealing surface area between the rotary seal ring 9 and the stationary seal ring 6 will be qualitatively reduced in the region (B). Therefore, the area of the heat generating surface can be reduced. Moreover,
As a large amount of fluid flows into and out of group 12 as it rotates, the heat generated on the sealing surface is stimulated.
Cooling action is performed effectively and thermal strain is suppressed. 'In addition, the number of formed dynamic pressure generating parts A, and the area A and □
゛□ The optimal value for the ratio of B changes depending on the sealing conditions, and the higher the viscosity and circumferential speed, the smaller the ratio of area A needs to be. Since they are differentiated, the theoretical calculation of the generated dynamic pressure is easy, and the difference with the actual value can be eliminated, making it practical. Further, although a spiral group is used as the dynamic pressure generating area A in FIGS. 1 to 3, as another embodiment of the present invention, a rotary seal ring 13 shown in FIG. The rotary seal ring 13, like the rotary seal ring 9 shown in FIG. 1, has dynamic pressure generating areas A and non-dynamic pressure generating areas B alternately provided along the circumferential direction. Alternatively, a group 14 having a shallow groove depth in a so-called Rayleigh step shape may be formed. In other words, the groove 14 having a shallow depth shown in FIG.
One end of the groove is open. Note that the material of the sealing surface lO explained in the embodiment needs to be a hard material in terms of wear resistance in the groove-processed part, but a soft material such as carbon can be used in the flat part. Furthermore, in the above embodiment description, the dynamic pressure generating portion A was formed on the outer diameter side of the seal ring 9, and the seal portion was formed on the inner diameter side.
Depending on the sealing conditions, these relationships may be reversed. Furthermore, it goes without saying that the present invention can be utilized not only under conditions of high viscosity liquid and high circumferential speed, but also under conditions of medium viscosity liquid and intermediate speed. 4. Brief description of the drawings FIGS. 1 and 2 show an embodiment of the present invention. FIG. 1 is a front view of the rotary seal ring, and FIG.
It is a cutaway view taken along the line. Figure 3 is a cross-sectional view for explaining the contact mechanical seal structure of a dynamic pressure type valve, and Figures 4 to 7 show the main points of the sealing surface, respectively, showing conventional measures for generating dynamic pressure against high viscosity liquid and high circumferential speed conditions. FIG. 8 is a front view of a non-rotating seal ring showing another embodiment of the present invention. 1... Casing (fixed side) 2... Rotating shaft (rotating side) 6... Fixed seal ring 7... Spring 9... Rotating seal ring 11.14... Group with shallow groove depth 12...-Group A with deep groove depth...Dynamic pressure generation area B...Non-dynamic pressure generation area Patent applicant Nippon Biller Industries Co., Ltd. Agent Patent attorney Takashi Suzue - II8Ii

Claims (1)

[Claims] (1) A dynamic pressure generating group (with a rotary seal ring fixed on the rotating side and a fixed seal ring held on the stationary side via a bellows) facing each other and having an advancing angle on the sealing surface.
grooves), the sealing surface is divided alternately and circumferentially into a dynamic pressure generating area and a non-dynamic pressure generating area, and in the dynamic pressure generating area, a group having a shallow groove depth is formed. A dynamic pressure type valve contact mechanical seal formed by forming a group with a deep groove depth in a non-dynamic pressure generating area.