CN203335870U - Self-pumping fluid-dynamic-pressure-type mechanical seal - Google Patents

Abstract

The utility model relates to a self-pumping fluid dynamic pressure mechanical seal. More than 3 groups of back-curved fluid grooves are provided on the end face of the dynamic ring seal. Each fluid groove is composed of a slope groove and a flat groove. The outlet is located at the dynamic ring seal On the outer side of the moving ring, the inlet is located in the middle of the sealing surface of the moving ring, and communicates with the sealing chamber through the axial channel or the combination of axial and radial channels on the moving ring; when the moving ring rotates, the medium in the fluid-type groove is accelerated to a high speed Under the action of centrifugal force, the fluid flows to the outer diameter side of the moving ring and is pumped into the sealing cavity, and forms a low-pressure area at the entrance of the back-curved fluid groove, and the medium in the sealing cavity passes through the moving ring under the action of pressure difference The axial channel or the combined axial and radial channels connected with the sealing chamber flow into the back-curved fluid groove to form a new self-pumping cycle; when the high-speed fluid is pumped out, as the flow cross-sectional area gradually Increase, the flow rate decreases, the pressure increases, and a certain opening force is formed; the seal has good self-lubrication, self-flushing, anti-solid particle interference ability and superior sealing performance.

Description

Self-Pumping Hydrodynamic Mechanical Seals

technical field

The utility model belongs to the technical field of sealing, in particular to a self-pumping mechanical seal with hydrodynamic pressure effect, which is suitable for sealing the rotating shafts of various compressors, centrifugal pumps, reactor stirrers and other rotating machines.

Background technique

At present, non-contact mechanical end seals are widely used in centrifugal compressors, fans, centrifugal pumps and other equipment in petroleum, chemical, chemical fiber, papermaking, electric power and metallurgical industries. The principle of hydrodynamics forms a hydrodynamic wedge, which generates the opening force of the end face, and achieves the purpose of reducing the wear of the sealing end face. For example, a hydrodynamic and static pressure combined non-contact mechanical seal with a single row of spiral grooves disclosed in US US4212475, China ZL00239203. 8 discloses a single-row fluid type groove upstream pumping mechanical seal and the centrifuge dry gas seal disclosed in ZL201020106087.8. In these patents, whether it is a dry gas seal or an upstream pumped mechanical seal, the medium that forms the hydrodynamic pressure is pumped into the groove, and the end face opening force is generated at the root of the groove to separate the dynamic ring from the static ring and reduce the seal. At the same time, the friction of the end face also increases the leakage rate between the moving ring and the static ring, especially if the pumped medium contains particles, it will also damage the end face of the seal dam and accelerate the failure of the seal. For this reason, some known technologies have been improved, such as a hydrodynamic double-row spiral groove end face seal disclosed in US Patent US5201531, a double-ring spiral groove end face seal disclosed in Chinese Patent ZL96108614. Fluid-type groove self-lubricating non-contact mechanical seals have effectively reconciled this contradiction. Under a given rotation, this sealing device uses one row of helical grooves to pump the sealing fluid downstream, and the other row of helical grooves pumps the sealing fluid upstream, and pumps pressure through the pump generated by the two helical grooves. The pressure difference between the inner and outer sides of the sealing end face is balanced to achieve zero leakage of the spiral groove end face seal. However, this type of seal has a relatively complicated structure and a large installation space, and is only suitable for working conditions where the fluid pressure difference on both sides of the seal end face is not large.

Contents of the invention

The purpose of this utility model is to propose a self-pumping mechanical seal with a hydrodynamic pressure effect that is suitable for a wide range of fluid pressure differences on both sides of the sealing end face, so as to solve the problem of low opening force and leakage rate of the existing single-row spiral groove mechanical seal end face. Large size, poor anti-particle interference ability, complex sealing end face structure of double-row spiral groove mechanical seal, and large installation space. Under the same conditions, it has greater working flexibility and zero leakage than the above-mentioned seal.

The technical scheme of the utility model is:

A self-pumping fluid dynamic pressure mechanical seal, which is installed between the casing 2 of the rotating machine and the shaft 10 or sleeve 8, and consists of a moving ring 3, an O-ring 12 for the moving ring, a static ring 11, and an O-ring for the static ring. O-ring 5, spring 7, static ring seat 14, etc.; the end face of the moving ring 3 that cooperates with the static ring 11 is divided into a groove area and a seal dam 37, the groove area is distributed on the outer part of the end face, and the seal dam 37 is distributed on the end face Outer part; more than 3 groups of back-curved fluid-type grooves 39 are set in the groove area, and the sealing surface between the backward-curved fluid-type grooves 39 forms a sealing weir;

The back-curved fluid groove 39 includes two parts: a slope groove 32 and a flat groove 33. The slope groove 32 is located at the large radius portion of the end surface of the moving ring 3, and the flat groove 33 is located at the small radius portion of the end surface of the moving ring 3;

The outlet of the back-curved fluid groove 39 is located at the outer diameter of the sealing surface of the moving ring 3, the inlet 31 is located in the middle of the sealing surface of the moving ring 3, and the inlet 31 of the backward-curved fluid groove 39 passes through the upper surface of the moving ring 3. The axial channel or combined axial and radial channel 30 communicates with the sealing chamber 1;

On both sides of the back-curved fluid groove 39, one side is the working surface 34, and the other side is the non-working surface 35;

The medium in the back-curved fluid-type groove 39 is accelerated into a high-speed fluid by the working surface of the backward-curved fluid-type groove 39 when the moving ring 3 rotates. The outer diameter side flows and is pumped into the sealing chamber 1, and a low-pressure area is formed at the inlet 31 of the back-curved fluid groove 39, and the medium in the sealing chamber 1 passes through the moving ring 3 and the sealing chamber 1 under the action of the pressure difference. The connected axial channels or combined axial and radial channels 30 flow into the back-curved fluid groove 39 to form self-pumping cycles again and again; this self-pumping cycle process again and again, on the one hand, realizes the mechanical seal. Self-lubricating; on the other hand, the continuous circulation of fluid between the sealing surfaces takes away the frictional heat between the sealing surfaces in time, realizing the self-flushing of the seal; and the effect of centrifugal force increases the fluid flow to the sealing surface of the moving ring 3 The power on the outside reduces the leakage rate of the fluid flowing to the inner side of the sealing surface of the moving ring 3; especially, the centrifugal force makes the sealed fluid containing solid particles entering the back-curved fluid groove 39 produce solid particles and matrix Separation, in which the solid particles with high density obtain a large centrifugal force, and are pumped out with the fluid and sent to the sealing chamber 1 again, and do not enter the sealing dam 37 area, avoiding abrasive wear between the sealing surfaces.

The fluid that is accelerated into a high speed by the back-curved fluid type groove 39 working surface 31 is pumped out of the back-curved fluid type groove 39. Larger, the flow rate decreases, the pressure increases, and the opening force that separates the moving ring 3 and the static ring 11 is formed.

The groove walls on both sides of the back-curved fluid groove 39 are helical.

The helixes of the groove walls on both sides of the back-curved fluid groove 39 have the same helix angle.

The helix angles of the helixes of the groove walls on both sides of the back-curved fluid groove 39 are different, and the helix angle of the working surface 34 is smaller than that of the non-working surface 35 .

The helix of the groove wall profiles on both sides of the back-curved fluid groove 39 is tangent to the round hole of the inlet 31 .

The cross-section of the joint between the axial and radial combination channels 30 on the moving ring 3 and the outer surface of the moving ring 3 is a wedge-shaped opening 38 .

Another technical solution of the utility model is:

A self-pumping fluid dynamic pressure mechanical seal, which is installed between the casing 2 of the rotating machine and the shaft 10 or sleeve 8, and consists of a moving ring 3, an O-ring 12 for the moving ring, a static ring 11, and an O-ring for the static ring. O-ring 5, spring 7, static ring seat 14, etc.; the end face of the moving ring 3 that cooperates with the static ring 11 is divided into a groove area and a seal dam 37, the groove area is distributed on the outer part of the end face, and the seal dam 37 is distributed on the end face The outer part; more than 3 groups of back-curved fluid-type grooves 39 are provided in the groove area, and the sealing surface between the back-curved fluid-type grooves 39 forms a sealing weir; the backward-curved fluid-type grooves 39 include slope grooves 32 and flat grooves 33 Two parts, the slope groove 32 is at the large radius part of the end face of the moving ring, and the flat groove 33 is at the small radius part of the end face of the moving ring; The circular ring groove 36 communicates, and the circular ring groove 36 has at least one axial channel or combined axial and radial channels 30 communicating with the sealing cavity 1 .

The circular ring groove 36 has the functions of collecting self-lubricating and self-flushing medium and preventing unevenness of the pumping medium and cavitation if the fluid replenishment at the inlet 31 of the backward curved fluid type groove 39 is not timely.

When the angle between the slope 32 surface and the end surface of the back-curved fluid groove 39 is 0 or rp=r2, it is a constant depth groove; when rp=ro, it is a single slope groove 32. By changing the number and parameters of the back-curved fluid grooves 39, the sealing requirements of different sealed media can be met.

Beneficial effects of the present invention

A self-pumping fluid dynamic pressure mechanical seal described in the utility model has the following advantages:

① With excellent sealing performance, it is suitable for centrifugal pumps, centrifugal compressors, mixing equipment and other rotating machinery shaft seals that transport various flammable, explosive, toxic and other process fluids, and can achieve microscopic leak-free sealing of fluids.

②When the moving ring rotates, particles with different masses produce different centrifugal forces, so that the self-pumping hydrodynamic mechanical seal of the utility model has the function of automatically removing solid particles, and can avoid abrasive wear of the seal dam.

③Wide range of application, can be used as both liquid seal and gas seal.

④The unique self-lubricating, self-cooling and flushing functions ensure the stability and durability of the mechanical seal.

⑤In the static state, the high-pressure side fluid is directly injected between the sealing surfaces, which eliminates the solid friction between the sealing surfaces at the moment of starting, and can quickly form a fluid film at the moment of starting to separate the two sealing surfaces, so the seal is also It is suitable as a shaft seal for rotating machinery with frequent start and stop.

⑥The high-pressure isolation fluid comes from the sealed medium, which saves the delivery system of the high-pressure isolation fluid, reduces the operating cost of the pump, and correspondingly improves the economic benefits.

Description of drawings

Figure 1 is a schematic diagram of the shaft section of a self-pumping hydrodynamic mechanical seal with a back-curved fluid groove and an inlet connected to the seal cavity through an axial channel on the moving ring.

Fig. 2 is a schematic diagram of the end face of the moving ring with a back-curved fluid groove.

Fig. 3 is a schematic diagram of the shaft section structure of a self-pumping hydrodynamic mechanical seal with a back-curved fluid groove and an inlet ring groove, and the inlet communicates with the seal cavity through the axial and radial combination channels on the moving ring.

Figure 4 is a schematic diagram of the end face of the moving ring with a back-curved fluid groove and an inlet ring groove.

FIG. 5 is a cross-sectional view along line A-A of FIG. 3 .

in,

R1- the inner radius of the sealing end face between the moving ring and the static ring;

R2- the outer radius of the sealing end face between the moving ring and the static ring;

Rp-groove step radius

Ro-groove entrance hole position radius

Rk-type groove entrance hole radius

R3-type groove inlet ring groove inner radius

R4-type groove inlet ring groove outer radius

G - the pumping direction of the fluid type tank;

β-helix angle;

h-flat groove depth

α- Angle between slope surface and end surface

w-rotation of the moving ring;

1-seal cavity; 2-casing; 3-moving ring; 30-axial channel or combined axial and radial channels; 31-inlet; 32-slope groove; 33-flat groove; 34-working surface; 35-non Working face; 36-circular ring groove; 37-seal dam; 38-wedge-shaped opening; 39-backbend fluid groove; 4-O-ring; 5-O-ring for stationary ring; 6-anti-rotation pin; 7-spring; 8-shaft sleeve; 9,13-set screw; 10-axis; 11-static ring; 12-O-ring for moving ring; 14-static ring seat.

Detailed ways

The implementation of the utility model will be described in detail below in conjunction with the accompanying drawings and examples.

Embodiment one

Figure 1 and Figure 2 describe a self-pumping fluid dynamic pressure mechanical seal, which is arranged between the casing 2 of the rotating machine and the shaft 10 or sleeve 8, and consists of a moving ring 3 and an O-ring 12 for the moving ring , static ring 11, static ring with O-ring 5, spring 7, static ring seat 14, etc.; the end face of the moving ring 3 that cooperates with the static ring 11 is divided into a groove area and a sealing dam 37, and the groove area is distributed on the outer part of the end face , the sealing dam 37 is distributed on the outer part of the end face; 12 groups of back-curved fluid-type grooves 39 are set in the groove area, and the sealing surface between the back-curved fluid-type grooves 39 forms a sealing weir;

The back-curved fluid groove 39 includes two parts: a slope groove 32 and a flat groove 33. The slope groove 32 is located at the large radius portion of the end face of the moving ring, and the flat groove 33 is located at the small radius portion of the end face of the moving ring;

The outlet of the back-curved fluid groove 39 is located at the outer diameter of the moving ring sealing surface, the inlet 31 is located in the middle of the sealing surface of the moving ring 3, and the inlet 31 of the backward-curved fluid groove 39 passes through the The axial channel 30 communicates with the sealing chamber 1;

On both sides of the back-curved fluid groove 39, one side is the working surface 34, and the other side is the non-working surface 35;

The medium in the back-curved fluid-type groove 39 is accelerated into a high-speed fluid by the working surface 34 of the backward-curved fluid-type groove 39 when the moving ring 3 rotates, and moves toward the moving ring along the non-working surface 35 under the centrifugal force. 3 The outer diameter side flows and is pumped into the sealing chamber 1, and a low-pressure area is formed at the inlet 31 of the back-curved fluid groove 39, and the medium in the sealing chamber 1 passes through the moving ring 3 and the sealing chamber under the action of the pressure difference. 1 The connected axial channel 30 flows into the backward curved fluid groove 39 to form a self-pumping cycle again and again; this self-pumping cycle process, on the one hand, realizes the self-lubrication of the mechanical seal; on the other hand , the continuous circulation of the fluid between the sealing surfaces takes away the frictional heat between the sealing surfaces in time, realizing the self-flushing of the seal; and the centrifugal force increases the power of the fluid flowing to the outside of the sealing surface of the moving ring 3, reducing the The leakage rate of the fluid flowing to the inner side of the sealing surface of the moving ring 3; especially, the effect of centrifugal force makes the sealed fluid containing solid particles entering the back-curved fluid groove 39 capable of separating the solid particles from the matrix, and the dense ones The solid particles obtain greater centrifugal force, and are pumped out with the fluid and sent back to the sealing chamber 1 without entering the area of the sealing dam 37, thereby avoiding abrasive wear between the sealing surfaces.

The fluid that is accelerated into a high speed by the back-curved fluid type groove 39 working surface 31 is pumped out of the back-curved fluid type groove 39. Larger, the flow rate decreases, the pressure increases, and the opening force that separates the moving ring 3 and the static ring 11 is formed.

The groove walls on both sides of the back-curved fluid groove 39 are helical.

The helixes of the groove walls on both sides of the back-curved fluid groove 39 have the same helix angle.

The helix of the groove wall profiles on both sides of the back-curved fluid groove 39 is tangent to the round hole of the inlet 31 .

Embodiment two

Figures 3 to 5 are another self-pumping hydrodynamic mechanical seal, the difference from Embodiment 1 is that the inlet 31 of the backward curved fluid groove 39 in this embodiment is sealed with the moving ring 3 The circular ring groove 36 in the middle of the surface is connected, and the circular ring groove 36 is provided with 6 axial and radial combination channels 30 communicating with the sealing chamber 1; the axial and radial combination channels 30 on the moving ring 3 are connected with the The cross-section of the junction of the outer circular surface of the moving ring 3 is a wedge-shaped opening 38; the circular ring groove 36 has 31 inlets for collecting self-lubricating and self-flushing media, preventing uneven pumping media, and a back-curved fluid type groove 39 If the fluid replenishment is not timely, the effect of cavitation will appear.

The rest of the structures and implementations are the same as in Embodiment 1.

Claims (7)

1. A self-pumping fluid dynamic pressure mechanical seal, which is arranged between the casing (2) and the shaft (10) or sleeve (8) of the rotating machine, and consists of a moving ring (3) and an O-shaped seal for the moving ring. Ring (12), static ring (11), static ring are made up of O-shaped ring (5), spring (7), static ring seat (14) etc., it is characterized in that: The end face of the moving ring (3) matched with the static ring (11) is divided into a groove area and a sealing dam (37), the groove area is distributed on the outer part of the end face, and the sealing dam (37) is distributed on the outer part of the end face; the groove area is provided with 3 There are more than one group of back-curved fluid-type grooves (39), and the sealing surface between the backward-curved fluid-type grooves (39) constitutes a sealing weir; The back-curved fluid groove (39) includes two parts: a slope groove (32) and a flat groove (33). Small radius part; The outlet of the backward curved fluid groove (39) is located at the outer diameter of the moving ring sealing surface, the inlet (31) is located in the middle of the moving ring (3) sealing surface, and the backward curved fluid groove (39) The inlet (31) communicates with the sealing chamber (1) through the axial channel on the moving ring (3) or the combined axial and radial channels (30); On both sides of the back-curved fluid groove (39), one side is the working surface (34), and the other side is the non-working surface (35). the 2. The self-pumping hydrodynamic mechanical seal according to claim 1, characterized in that: the groove walls on both sides of the backward curved fluid groove (39) are helical. the 3. The self-pumping fluid dynamic pressure mechanical seal according to claim 1 or 2, characterized in that: the helixes of the groove wall profiles on both sides of the back-curved fluid type groove (39) have the same helix horn. the 4. The self-pumping fluid dynamic pressure mechanical seal as claimed in claim 1 or 2, characterized in that: the helix angle of the helix of the groove wall profiles on both sides of the backward curved fluid groove (39) is not etc., the helix angle of the working surface (34) is less than the helix angle of the non-working surface (35). the 5. The self-pumping fluid dynamic pressure mechanical seal according to claim 1 or 2, characterized in that: the helix of the groove wall profiles on both sides of the back-curved fluid groove (39) and the inlet (31 ) circular hole is tangent. the 6. The self-pumping fluid dynamic pressure mechanical seal according to claim 1, characterized in that: the axial and radial combined holes (30) on the moving ring (3) and the outer circular surface of the moving ring (3) The cross-section of the joint is a wedge-shaped opening (38). the 7. A self-pumping fluid dynamic pressure mechanical seal, which is arranged between the casing (2) and the shaft (10) or sleeve (8) of the rotating machine, and is composed of a moving ring (3) and an O-shaped seal for the moving ring. Ring (12), static ring (11), static ring are made up of O-shaped ring (5), spring (7), static ring seat (14) etc., it is characterized in that: The end face of the moving ring (3) matched with the static ring (11) is divided into a groove area and a sealing dam (37), the groove area is distributed on the outer part of the end face, and the sealing dam (37) is distributed on the outer part of the end face; the groove area is provided with 3 There are more than one group of back-curved fluid-type grooves (39), and the sealing surface between the backward-curved fluid-type grooves (39) constitutes a sealing weir; The back-curved fluid groove (39) includes two parts: a slope groove (32) and a flat groove (33). Small radius parts; The inlet (31) of the backward curved fluid type groove (39) communicates with the circular ring groove (36) arranged in the middle of the sealing surface of the moving ring (3), and at least one of the circular ring grooves (36) is connected with An axial channel or a combination of axial and radial channels (30) connected to the sealing cavity (1). the

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