CN111043313A

CN111043313A - Shaft seal structure

Info

Publication number: CN111043313A
Application number: CN201911167850.XA
Authority: CN
Inventors: 黎鑫
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2019-11-25
Filing date: 2019-11-25
Publication date: 2020-04-21

Abstract

The invention relates to a shaft seal structure, which comprises a shell provided with a shaft hole and a rotating shaft arranged in the shaft hole, wherein high-pressure fluid and low-pressure fluid are respectively arranged on two sides of the shell, the shaft seal structure comprises a sealing ring arranged at the shaft hole and at least one pressure transformation mechanism, the sealing ring is in contact with the rotating shaft and seals a gap between the rotating shaft and the shaft hole, the pressure transformation mechanism partially or completely rotates along with the rotating shaft, the rotation enables pressure change to be formed in the pressure transformation mechanism, and the pressure transformation mechanism utilizes the pressure change to change the pressure difference of the fluid on two sides of the sealing ring. The invention reduces the fluid pressure difference on the two sides of the sealing ring, thereby reducing the abrasion of the sealing ring, prolonging the service life of the sealing ring and being beneficial to improving the output torque of the rotating shaft.

Description

Shaft seal structure

Technical Field

The invention belongs to the sealing technology of a revolute pair between a shell and a rotating shaft, and particularly relates to a shaft seal structure.

Background

Sealing between the shaft and the housing is a very important engineering problem. Fig. 1 shows a shaft 1 ' passing through a shaft hole 3 ' of a housing 2 '. The left side of the housing 2' is the high pressure side and the right side thereof is the low pressure side. In order to prevent the fluid on the high pressure side from flowing into the low pressure side through the gap between the rotating shaft 1 'and the housing 2' (referred to as leakage), a seal ring 4 'is usually disposed at the shaft hole 3'. The sealing ring 4 'is pressed on the rotating shaft 1' under the action of the fluid pressure difference on the two sides, and the leakage is blocked. The larger the fluid pressure difference between the two sides is, the larger the pressing force borne by the seal ring 4 ' is, and then after the rotating shaft 1 ' rotates, a large frictional resistance is generated between the rotating shaft 1 ' and the seal ring 4 ', and meanwhile, the more serious the abrasion of the seal ring is, so that the service life of the seal ring 4 ' is shortened.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a shaft seal structure, wherein a pressure changing mechanism is arranged at a shaft hole of a shell, so that the fluid pressure difference at two sides of a sealing ring is reduced, the abrasion and the frictional resistance of the sealing ring are reduced, the service life of the sealing ring is prolonged, and the output torque of a rotating shaft is favorably improved.

The invention is realized in such a way, and provides a shaft seal structure, which comprises a shell provided with a shaft hole and a rotating shaft arranged in the shaft hole, wherein high-pressure fluid and low-pressure fluid are respectively arranged on two sides of the shell, the shaft seal structure comprises a sealing ring arranged at the shaft hole and at least one pressure transformation mechanism, the sealing ring is in contact with the rotating shaft and seals a gap between the rotating shaft and the shaft hole, the pressure transformation mechanism partially or completely rotates along with the rotating shaft, the rotation enables pressure change to be formed in the pressure transformation mechanism, and the pressure transformation mechanism utilizes the pressure change to change the pressure difference of the fluid on two sides of the sealing ring.

In some occasions, the pressure transformation mechanism is arranged on the high-pressure side of the sealing ring, and the pressure of the high-pressure side of the sealing ring is reduced to reduce the fluid pressure difference on the two sides of the sealing ring; in other cases, the pressure varying mechanism is installed on the low pressure side of the seal ring to reduce the fluid pressure difference across the seal ring by increasing the pressure on the low pressure side of the seal ring. The two mounting modes achieve the same purpose and are used for reducing the fluid pressure difference on two sides of the sealing ring so as to reduce the abrasion and friction force of the sealing ring, prolong the service life of the sealing ring and be beneficial to improving the output torque of the rotating shaft.

In some extreme situations or special requirements, the pressure changing mechanism can also be used for increasing the pressure of the sealing ring on the high-pressure side or reducing the pressure of the sealing ring on the low-pressure side so as to increase the fluid pressure difference on two sides of the sealing ring and realize specific technical requirements, for example, the friction between the sealing ring and the rotating shaft is increased to improve the damping performance of the rotating shaft.

Further, the pressure transformation mechanism comprises an axial flow pushing device, the axial flow pushing device partially or completely rotates along with the rotating shaft, so that fluid in the pressure transformation mechanism is acted by axial thrust, pressure change is formed in the axial direction by the axial thrust, namely, the pressure gradually rises along the direction of the axial thrust, one end of the axial flow pushing device is communicated to one side of the sealing ring through a flow path, the pressure of the end of the axial flow pushing device is equal to the fluid pressure of the side of the sealing ring, the fluid pressure of the side of the sealing ring is changed, and therefore the effect of changing the fluid pressure difference of the two sides of the sealing ring is achieved.

Furthermore, the axial flow pushing device comprises a threaded cylinder, the pressure changing mechanism further comprises a cover body matched with the threaded cylinder, the threaded cylinder is sleeved on the rotating shaft, is fixed with the rotating shaft and rotates along with the rotating shaft, the threaded cylinder rotates in the cover body, one end of the cover body is connected with the shell to form a closed end, and the other end of the cover body is open; the outer surface of the threaded cylinder is provided with a thread-shaped structure; when the threaded cylinder rotates in the cover body, the thread-shaped structure generates axial thrust on fluid in the cover body, so that the fluid at two ends of the threaded cylinder generates pressure change in the axial direction, and the pressure at the closed end of the cover body is communicated to one side of the sealing ring, so that the effect of changing the pressure difference at two sides of the sealing ring is achieved.

By utilizing different combinations of the thread turning direction of the thread cylinder and the rotation direction of the rotating shaft, the direction of the axial thrust can be changed, and the pressure change direction of the thread cylinder is further changed. According to actual needs, the high-pressure end or the low-pressure end of the transformation mechanism is arranged on the high-pressure side or the low-pressure side of the sealing ring.

The pressure transformation mechanism is arranged on the high-pressure side of the sealing ring, and the low-pressure end of the threaded cylinder is arranged on the closed end of the cover body and communicates the pressure of the low-pressure end of the threaded cylinder to the high-pressure side of the sealing ring. The installation mode of the pressure transformation mechanism reduces the fluid pressure at the high-pressure side of the sealing ring, thereby reducing the fluid pressure difference at the two sides of the sealing ring.

The pressure transformation mechanism is arranged on the low-pressure side of the sealing ring, and the high-pressure end of the threaded cylinder is arranged on the closed end of the cover body and communicates the pressure of the high-pressure end of the threaded cylinder to the low-pressure side of the sealing ring. The installation mode of the pressure transformation mechanism improves the fluid pressure at the low-pressure side of the sealing ring, thereby reducing the fluid pressure difference at the two sides of the sealing ring.

Further, the pressure changing mechanism comprises a rotational flow generating device, and part or all of the rotational flow generating device rotates along with the rotating shaft, so that the fluid in the pressure changing mechanism forms a rotating fluid rotating around the rotating shaft. The centrifugal inertia force generated by the rotating fluid causes the fluid to form pressure variation in the radial direction, namely the pressure of the near-axis side of the rotating fluid is low while the pressure of the far-axis side of the rotating fluid is high. One side of the rotating fluid is communicated with one side of the sealing ring in pressure, and the fluid pressure of the sealing ring at the side is changed, so that the function of changing the fluid pressure difference at two sides of the sealing ring is achieved.

The rotational flow generating device of the pressure changing mechanism is not influenced by the rotation direction of the rotating shaft, and the fluid pressure change is always low at the near-shaft side pressure and high at the far-shaft side pressure. The pressure of the rotary flowing fluid is communicated to one side of the sealing ring according to the requirement, so that the effect of changing the fluid pressure difference on the two sides of the sealing ring can be achieved.

When the rotational flow generating device is positioned on the high-pressure side of the sealing ring, the far-shaft side of the rotating fluid is communicated with the outside, the near-shaft side pressure of the rotating fluid is communicated to the high-pressure side of the sealing ring, and the fluid pressure on the high-pressure side of the sealing ring is reduced, so that the effect of reducing the fluid pressure difference on the two sides of the sealing ring is achieved. When the rotational flow generating device is positioned on the low-pressure side of the sealing ring, the near-axis side pressure of the rotating fluid is communicated with the outside, the far-axis side pressure of the rotating fluid is communicated to the low-pressure side of the sealing ring, and the low-pressure side fluid pressure of the sealing ring is increased, so that the effect of reducing the fluid pressure difference on the two sides of the sealing ring is achieved.

Further, whirl generating device includes rotor and stationary plane, the rotor is fixed in the pivot and rotates along with the pivot, the stationary plane does not rotate along with the pivot, there is the fluid layer between rotor and the stationary plane, works as when the rotor is followed the pivot and is rotated, the fluid layer is formed round the rotatory rotating fluid of pivot by the rotor drive, and one of them side pressure of rotating fluid communicates to one side of sealing washer, plays the effect that changes the pressure difference in sealing washer both sides.

The pressure changing mechanism is arranged in such a way that the steering problem of the rotating shaft is not considered, the fluid pressure change is always low at the side close to the shaft and high at the side far from the shaft, and the fluid pressure change is independent of the rotating direction of the rotating shaft. The rotor is mounted at different positions as required to vary the fluid pressure differential across the seal ring.

Further, the fixing surface is a surface on the transformer mechanism or a wall surface of the housing.

Furthermore, the pressure changing structure is arranged on the high-pressure side of the shell, and the near-axis side pressure of the rotating fluid is communicated to one side of the sealing ring, so that the function of reducing the pressure difference between the two sides of the sealing ring is achieved.

Furthermore, the pressure transformation mechanism is arranged on the low-pressure side of the shell, and the pressure transformation mechanism further comprises a cylinder body, one end of the cylinder body is fixed with the shell to form a closed end, the other end of the cylinder body is connected with the fixed surface, the far-axis side pressure of the rotating fluid is communicated to one side of the sealing ring, and the effect of reducing the pressure difference on the two sides of the sealing ring is achieved. The cylinder is provided to establish a communication flow path between the pressure changing mechanism and the seal ring.

Furthermore, a flow blocking body is further arranged in the cylinder body and is positioned in a communication flow path between the sealing ring and the fluid layer, and the flow blocking body does not rotate along with the rotating shaft and is fixed on the side wall of the shell.

This dampens the pressure variations created by the fluid layer to some extent, since the fluid in the communicating flow path between the sealing ring and the fluid layer will follow the rotation of the rotor due to the viscosity of the fluid. Therefore, some measures are required to reduce the driving action of the rotor on the fluid other than the fluid layer. There are many possible solutions that can be used, for example, to increase the distance between the rotor and the wall surface of the housing, which impairs the driving action of the fluid viscosity. For another example, some fixed flow-resisting structures are installed between the rotor and the wall surface of the housing to resist the formation of the rotating flow of the fluid layer. The flow blocking structure may be a plurality of flow blocking bodies fixed to the housing, the flow blocking bodies blocking rotation of the fluid.

Further, a stirring blade is provided on the fluid layer side of the rotating body.

The rotor drives the fluid layer fluid to rotate and form pressure change through the viscous action of the fluid. However, the viscous driving action of the fluid is relatively weak, resulting in insufficient rotation of the fluid layer. Therefore, the provision of the agitating blade on the rotor to agitate the fluid in the fluid layer can accelerate the rotational speed of the fluid, and the variation in the fluid pressure inside the fluid layer can become more significant.

Further, the pressure changing mechanism comprises at least one communication hole, the communication hole is communicated with the internal fluid and the external fluid of the pressure changing mechanism, the fluid forms convection flow through the communication hole, and the convection flow enables the internal fluid and the external fluid of the pressure changing mechanism to be in a state of convection flow.

Further, the communicating hole is arranged on the cover body and close to the sealing ring.

Further, the communicating hole is arranged on the rotating body and close to the sealing ring.

Further, the communication hole is arranged on the fixing plate cylinder and close to the sealing ring.

The communicating hole is arranged, the convection flow of fluid is constructed between the inside and the outside of the pressure transformation mechanism, the friction heat at the sealing ring can be taken away by the convection flow of the fluid, the temperature of the sealing ring is reduced, and the service life of the sealing ring is prolonged.

Further, the shaft seal structure comprises a plurality of pressure transformation mechanisms, the pressure transformation mechanisms are arranged on the same side of the shell, the high-pressure end of one pressure transformation mechanism is communicated with the low-pressure end of the other pressure transformation mechanism adjacent to the high-pressure end of the other pressure transformation mechanism, the pressure changes of the pressure transformation mechanisms form a superposition relation after the pressure transformation mechanisms form the series connection structure, and the fluid pressure difference on two sides of the sealing ring is changed by utilizing the total pressure change after the superposition.

Compared with the prior art, the shaft seal structure comprises a shell, a rotating shaft, a sealing ring and at least one pressure transformation mechanism, wherein the sealing ring is in contact with the rotating shaft and seals a gap between the rotating shaft and a shaft hole to form sealing, the pressure transformation mechanism partially or completely rotates along with the rotating shaft, pressure change is formed in the pressure transformation mechanism through the rotation, and the pressure transformation mechanism changes fluid pressure difference on two sides of the sealing ring by utilizing the internal pressure change formed by the rotation, so that the abrasion and the friction of the sealing ring are reduced, and the service life of the sealing ring is prolonged.

Drawings

FIG. 1 is a schematic structural diagram of a sealing ring in a sealing state at a shaft hole between a rotating shaft and a housing in the prior art;

FIG. 2 is a schematic structural view of a first preferred embodiment of the shaft seal structure of the present invention;

FIG. 3 is a schematic structural view of a second embodiment of the shaft seal structure of the present invention;

FIG. 4 is a schematic structural view of a third embodiment of the shaft seal structure of the present invention;

FIG. 5 is a schematic structural view of a fourth embodiment of the shaft seal structure of the present invention;

FIG. 6 is a schematic structural view of a fifth embodiment of the shaft seal structure of the present invention;

FIG. 7 is a schematic structural view of a sixth embodiment of the shaft seal structure of the present invention;

FIG. 8 is a schematic structural view of a seventh embodiment of the shaft seal structure of the present invention;

FIG. 9 is a schematic structural view of an eighth embodiment of the shaft seal structure of the present invention;

FIGS. 10a and 10b are schematic views of fixing surface structures of two different shapes of a ninth embodiment of the shaft seal structure of the present invention, respectively;

FIG. 11 is a schematic structural view of a tenth embodiment of the shaft seal structure of the present invention;

FIG. 12 is a schematic structural view of an eleventh embodiment of the shaft seal structure of the present invention;

FIG. 13 is a schematic structural view of a twelfth embodiment of the shaft seal structure of the present invention;

FIG. 14a is a schematic structural view of a thirteenth embodiment of the shaft seal structure of the present invention;

FIG. 14b is a schematic structural view of a state in which the rotor is combined with the agitating blade in FIG. 14 a;

FIG. 15 is a schematic structural view of a fourteenth embodiment of the shaft seal structure of the present invention;

FIG. 16 is a schematic structural view showing a fifteenth embodiment of the shaft seal structure of the present invention;

fig. 17 is a schematic structural view of a sixteenth embodiment of the shaft seal structure of the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

Referring to fig. 2, a first preferred embodiment of the shaft seal structure of the present invention includes a housing 2 having a shaft hole 3 and a rotating shaft 1 disposed in the shaft hole 3. On both sides of the housing 2, a high-pressure and a low-pressure fluid are provided, respectively. The shaft seal structure also comprises a sealing ring 4 and a pressure changing mechanism 5 which are arranged at the shaft hole 3.

The sealing ring 4 is contacted with the rotating shaft 1 and blocks a gap between the rotating shaft 1 and the shaft hole 3. Part or all of the transformation mechanism 5 rotates together with the rotating shaft 1, and the rotation forms pressure change inside the transformation mechanism 5. The pressure varying mechanism 5 varies the fluid pressure difference between both sides of the seal ring 4 by using the internal pressure variation caused by the rotation. For example, when the transformer mechanism is arranged on the high-pressure side of the sealing ring, the internal low pressure of the transformer mechanism is communicated to the high-pressure side of the sealing ring, so that the high-pressure side pressure of the sealing ring is reduced, the pressure difference between two sides of the sealing ring is also reduced, the abrasion and the friction resistance of the sealing ring can be reduced, the service life of the sealing ring is prolonged, and the output torque of the rotating shaft is improved.

The pressure changing mechanism 5 of the present invention can have various structural forms, and various composition modes of the shaft seal structure of the present invention will be further described with reference to specific embodiments.

Example 2

Referring to FIG. 3, a second embodiment of the shaft seal structure of the present invention is shown. The pressure changing mechanism 5 comprises an axial flow pushing device. The axial flow-pushing device comprises a threaded cylinder 6 and a cover body 7. The threaded cylinder 6 is fixedly sleeved on the rotating shaft 1 and rotates along with the rotating shaft 1, and the threaded cylinder 6 rotates in the cover body 7. One end (shown as the right end) of the cover body 7 is hermetically connected with the shell 2, and the threaded cylinder 6 is isolated from being directly communicated with outside fluid in the circumferential direction. The outer surface of the threaded cylinder 6 is provided with threads or a thread-like structure.

When the threaded cylinder 6 rotates in the housing 7, the threads generate axial thrust on the fluid in the housing 7, so that the fluid at two ends of the threaded cylinder 6 generates pressure change and is divided into a high-pressure end 61 and a low-pressure end 62. The difference between the thread direction of the threaded cylinder 6 and the rotation direction of the rotating shaft 1 causes the positions of the high-voltage end 61 and the low-voltage end 62 of the voltage transformation mechanism 5 to be different.

In fig. 3, the high pressure side of the fluid is located at the left side of the housing 2, at a pressure PH; the fluid low pressure side is located on the right side of the housing 2, and its pressure is PL. The screw thread is right-handed screw thread, pivot 1 anticlockwise rotates, the axial thrust direction level left that produces after the screw thread section of thick bamboo 6 rotates, as shown by the arrow in the figure.

The transformation mechanism 5 is arranged on the high-pressure side of the sealing ring 4. The low pressure end of the threaded barrel 6 is adjacent the housing 2. The low pressure end 62 of the threaded cylinder 6 communicates with the left side of the seal ring 4, and the side pressure of the seal ring 4 is significantly reduced, thereby effectively reducing the fluid pressure difference between the two sides of the seal ring 4 and reducing the abrasion and friction between the seal ring 4 and the rotating shaft 1.

It is clear that the pressure on the left side of the pressure swing mechanism 5 is equal to the fluid pressure PH on the high pressure side, and the pressure on the right side of the pressure swing mechanism 5 is less than the pressure PH. Since the left pressure of the seal ring 4 is equal to the right pressure of the pressure varying mechanism 5, the left pressure of the seal ring 4 is also lower than PH. Therefore, the fluid pressure difference across the seal ring 4 is less than (PH-PL), which reduces the pressing force of the fluid acting on the seal ring 4, thereby reducing wear and friction between the seal ring 4 and the rotary shaft 1.

Other structures and functions are the same as those of embodiment 1, and are not described again.

Example 3

Referring to FIG. 4, a third embodiment of the shaft seal structure of the present invention is shown. In this embodiment, the pressure changing mechanism 5 is provided on the low pressure side of the seal ring 4. The high pressure end 61 of the threaded cylinder 6 is adjacent to the sealing ring 4. One end (shown as the left end) of the cover body 7 is hermetically connected with the shell 2, and the threaded cylinder 6 is isolated from being directly communicated with outside fluid in the circumferential direction. The screw thread is right-handed screw thread, pivot 1 anticlockwise rotates, the axial thrust direction level left that produces after the screw thread section of thick bamboo 6 rotates, as shown by the arrow in the figure. The high-pressure end 61 of the threaded cylinder 6 is communicated with the right side of the sealing ring 4, the pressure of the sealing ring 4 on the side is obviously increased, so that the fluid pressure difference on two sides of the sealing ring 4 is effectively reduced, and the abrasion and the friction between the sealing ring 4 and the rotating shaft 1 are reduced.

Other structures and functions are the same as those of embodiment 2, and are not described again.

Example 4

Referring to FIG. 5, a fourth embodiment of the shaft seal structure of the present invention is shown. In this embodiment, the same transformation mechanism 5 as in embodiment 2 is provided on the left side of the seal ring 4, and the same transformation mechanism 5 as in embodiment 3 is provided on the right side of the seal ring 5, and the structures and functions of the transformation mechanisms 5 at these two places are respectively the same as those in

embodiments

2 and 3, and the other structures and functions are also the same as those in

embodiments

2 and 3, and are not described again.

Example 5

Referring to FIG. 6, a fifth embodiment of a shaft seal structure according to the present invention is shown. In the above embodiment, one side of the seal ring 4 is communicated with the pressure changing mechanism 5. The fluid of this side is isolated from the external fluid. Then, heat generated by the mutual friction of the rotary shaft 1 and the seal ring 4 is accumulated inside the pressure changing mechanism, resulting in an increase in the temperature of the fluid in the vicinity of the seal ring 4. The high temperature affects the elasticity of the sealing ring 4 and accelerates the ageing of the sealing ring material. To solve this problem, the communicating hole 19 is provided in the pressure changing mechanism 5. The communication hole 19 communicates the internal fluid and the external fluid of the pressure changing mechanism 5. The fluid flows through the communication hole 19 in a convection manner, and the fluid at the seal ring 4 is in a flowing state.

In this embodiment, a communication hole 19 is provided on the closed end of the cover 7, and the communication hole 19 is adjacent to the seal ring 4. When the rotating shaft 1 is rotated in the direction indicated in the figure, the pressure on the right side of the axial flow pushing device is lower than the external pressure, and then the fluid outside the cover 7 enters the cover 7 through the communication hole 19 and flows out under the action of the axial pushing force. This creates a convective flow inside the pressure swing mechanism 5. And because the communication hole 19 is arranged at a position close to the sealing ring, the convection flow of the fluid can drive the fluid near the sealing ring 4 to flow, so as to take away the friction heat at the sealing ring 4, reduce the temperature of the sealing ring 4 and prolong the service life of the sealing ring 4.

Example 6

Referring to FIG. 7, a sixth embodiment of a shaft seal structure according to the present invention is shown. In this embodiment, the communication hole 19 of the pressure changing mechanism 5 is provided in the housing 2, the communication hole 19 communicates between the fluid outside and the fluid inside the cover 7, and the fluid inside and outside the cover 7 forms a convection flow through the communication hole 19. The communication hole 19 is arranged at a position close to the sealing ring 4, and the convection flow of the fluid can drive the fluid near the sealing ring 4 to flow, take away the friction heat at the sealing ring 4, reduce the temperature of the sealing ring 4 and prolong the service life of the sealing ring 4.

The other structures and functions are the same as those of embodiment 5, and are not described again.

Example 7

Referring to FIG. 8, a seventh embodiment of a shaft seal structure according to the present invention is shown. In this embodiment, the pressure changing mechanism 5 is a swirling flow generating device including a rotating body 8 and a fixed surface. In the present embodiment, the rotating body 8 is in the shape of a flat plate. The fixed surface is the right side wall of the housing 2. The rotating body 8 is fixed on the rotating shaft 1 and rotates along with the rotating shaft 1. The rotor 8 is located on the high pressure side of the sealing ring 4 and close to the sealing ring 4. A fluid layer 9 is formed between the rotor 8 and the stationary surface. The fixed surface does not rotate along with the rotating shaft 1. When the rotor 8 rotates along with the rotating shaft 1, the fluid in the fluid layer 9 moves along with the rotor 8 under the driving action of the viscous force of the fluid, and forms a rotating flow rotating around the rotating shaft. Under the centrifugal inertial force of the rotating fluid, a radial pressure change is formed in the fluid layer 9, that is, the near-axis pressure is low and the far-axis pressure is high. The proximal side of the fluid layer 9 communicates with the sealing ring 4. On the distal side of said fluid layer 9 is in communication with the surroundings of the rotor 8.

It is clear that the fluid layer 9 has a distal pressure equal to the pressure PH of the high pressure side of the housing 2, and that the fluid layer 9 has a proximal pressure lower than PH. The radial inner side of the fluid layer 9 is communicated with the high-pressure side of the sealing ring 4, so that the pressure of the side of the sealing ring 4 is lower than PH, and the pressure difference between the two sides of the sealing ring 4 is smaller than (PH-PL), thereby reducing the pressing force of the sealing ring 4, relieving the abrasion problem of the sealing ring 4 and reducing the friction force between the sealing ring 4 and the rotating shaft 1. Thus, the pressure change of the fluid layer 9 is always low on the near-axis side and high on the far-axis side regardless of the rotation direction of the rotating shaft 1.

In embodiments 2 to 6, when the rotation direction of the rotating shaft 1 is changed, the axial thrust changes the direction, and the high-pressure end and the low-pressure end are switched. This is not the case with the mechanism of the present embodiment.

Other structures and functions are also the same as those of embodiment 1, and are not described again.

Example 8

Referring to fig. 9, an eighth embodiment of the shaft seal structure of the present invention is shown. In this embodiment, the pressure changing mechanism 5 is a swirling flow generating device including a rotating body 8 and a fixed surface. The fixing surface is a fixing body 10 fixed to the housing 2. The fixed body 10 is located on the same side of the rotating body 8. The fluid layer 9 is formed between the stator 10 and the rotor 8.

The other structures and functions are the same as those of embodiment 7, and are not described again.

Example 9

Referring to fig. 10a and 10b, a ninth embodiment of the shaft seal structure of the present invention is shown. In this embodiment, the pressure changing mechanism 5 is a swirling flow generating device including a rotating body 8 and a fixed surface. The fluid layer 9 between the fixed surface and the rotating body 8 is not limited to a planar shape, but may have other shapes, for example, a conical cylindrical shape in fig. 10a and a curved surface shape in fig. 10 b. Regardless of the shape of the fluid layer 9, the rotor 8 can drive the fluid layer 9 to rotate around the rotation axis 1, and pressure variations can be formed inside the rotating fluid layer 9.

The other structures and functions are the same as those of embodiment 8, and are not described again.

Example 10

Referring to fig. 11, a tenth embodiment of a shaft seal structure according to the present invention is shown. In this embodiment, the pressure changing mechanism 5 is a swirling flow generating device including a rotating body 8 and a fixed surface. The fixed surface is the inner side surface 10 of the cylinder 11. The cylinder 11 is sleeved on the rotating shaft 1, and one end of the cylinder is hermetically fixed on the wall surface of the low-pressure side of the shell 2. The rotor 8 is disposed in the cylinder 11. The fluid layer 9 is arranged between the inner side 10 and the rotor 8. The cylindrical body 11, the rotating shaft 1, and the housing 2 constitute a communication flow path that communicates the distal shaft side of the fluidized bed 9 with the seal ring 4. The fluid on the near-axis side of the flowing layer 9 is communicated with the fluid of the peripheral environment of the pressure changing mechanism 5, namely the low-pressure side fluid through the gap between the cylinder 11 and the rotating shaft 1.

Example 11

Referring to fig. 12, an eleventh embodiment of a shaft seal structure of the present invention is shown. In this embodiment, the pressure changing mechanism 5 is a swirling flow generating device including a rotating body 8 and a fixed surface in this embodiment. A choke body 12 is also arranged in the cylinder body 11. The fluid blocking body 12 is located in a communication flow path between the sealing ring 4 and the fluid layer, in this embodiment, between the rotating body 8 and the casing 2, and the fluid blocking body 12 does not rotate along with the rotating shaft 1, and plays a role in blocking the fluid in the communication flow path from moving along with the rotating body 8. In the present embodiment, the bluff body 12 is a plurality of flat plates fixed on the side wall of the housing 2. The choke body 12 can be mounted on the cylinder 11 according to the actual installation situation. Without the spoiler, the fluid in the communication flow path is driven by the rotor 8 to form a rotational flow, which also forms a pressure change in the radial direction, which impairs the pressure change in the fluid layer 9. The flat plate of the choke body 12 can obstruct the rotational flow in the communicating flow path, and can eliminate this effect.

Example 12

Referring to fig. 13, a twelfth embodiment of a shaft seal structure according to the present invention is shown. In this embodiment, the same transformation mechanism 5 as in embodiment 8 is provided on the high-pressure side of the housing 2, and the same transformation mechanism 5 as in embodiment 10 is provided on the low-pressure side of the housing 2, and the structures and functions of the transformation mechanisms 5 at these two places are the same as those in

embodiments

8 and 10, respectively, and the other structures and functions are also the same as those in

embodiments

8 and 10, and thus, the description thereof is omitted.

Example 13

Referring to fig. 14a and 14b, a thirteenth embodiment of the shaft seal structure of the present invention is shown. In this embodiment, the pressure changing mechanism 5 is a swirling flow generating device including a rotating body 8 and a fixed surface. On said rotor 8 blades 13 are provided, said agitating blades 13 being radially fixed to the rotor 8, as shown in fig. 14 b. The agitating blades 13 are positioned in the fluid layer 9 between the rotating body 8 and the fixed surface, and the rotation of the fluid is enhanced by agitating the fluid in the fluid layer 9, so that the change of the fluid pressure in the fluid layer 9 is more obvious, the fluid pressure difference on two sides of the sealing ring 4 is more effectively reduced, and the abrasion and the frictional resistance between the sealing ring 4 and the rotating shaft 1 are reduced.

Example 14

Referring to FIG. 15, a fourteenth embodiment of a shaft seal structure according to the present invention is shown. In this embodiment, the pressure changing mechanism 5 is a swirling flow generating device including a rotating body 8 and a fixed surface. The rotor 8 is provided with a communication hole 19. The communication hole 19 is provided at a position close to the seal ring 4. The near-axis side of the fluid layer 9 between the rotating body 8 and the stationary surface forms a pressure lower than that of the outer peripheral environment, and thus the fluid of the outer peripheral environment flows into the fluid layer 9 through the communication holes 19 and flows out of the outer peripheral environment in the radial direction. Thus, convection is formed between the fluid inside and outside the pressure changing mechanism 5. Since the communication hole 19 is provided at a position close to the seal ring 4, the convection flow drives the fluid near the seal ring 4 to flow, and further takes away the frictional heat of the seal ring 4, thereby reducing the temperature of the seal ring 4 and prolonging the life of the seal ring 4.

Example 15

Referring to fig. 16, a fifteenth embodiment of the shaft seal structure of the present invention is shown. The shaft seal structure comprises a plurality of pressure transformation mechanisms 5, the pressure transformation mechanisms 5 are arranged on the same side of the shell 2, the high-pressure end of one pressure transformation mechanism 5 is communicated with the low-pressure end of the other pressure transformation mechanism 5 adjacent to the high-pressure end, after the pressure transformation mechanisms 5 form the series connection structure, the pressure changes of the pressure transformation mechanisms form a superposition relation, and the fluid pressure difference on two sides of the sealing ring 4 is changed by utilizing the total pressure change after the superposition. In the figure, two

transformation mechanisms

51 and 52 are provided in series on the high pressure side (left side) of the casing 2, and both the

transformation mechanisms

51 and 52 are swirl flow generating devices.

The transforming mechanism 51 includes a first rotating body 14 fixed on the rotating shaft 1. A first fluid layer 17 is formed between the rotor 14 and the wall surface of the housing 2. The transformation mechanism 52 includes a second rotating body 15 and a fixed body 16 fixed on the rotating shaft 1. The fixed surfaces of the rotor 15 and the stator 16 constitute a second fluid layer 18. One end of the cylinder 53 is fixedly connected with the shell 2 to form a closed end. The fixed body 18 is fixed to the cylindrical body 53, and forms a communication flow path that communicates the distal side of the first fluid layer 17 with the proximal side of the second fluid layer 18. The proximal pressure of the first fluid layer 17 is communicated to the seal ring 4. The pressure on one side of the sealing ring 4 is then equal to the ambient pressure minus the superposition of the pressure variations of the two fluid layers.

Example 16

Referring to FIG. 17, a sixteenth embodiment of the shaft seal structure of the present invention is shown. In this embodiment, two transformation mechanisms connected in series will be described as an example. The transforming mechanism 51 and the transforming mechanism 52 are located on the high-pressure side of the housing 2. The transformation mechanism 51 includes a swirl flow generating device. The swirl generating device comprises a rotor 14 fixed to the shaft 1. A fluid layer 17 is formed between the rotor 14 and the wall surface of the housing 2. The pressure changing mechanism 52 includes an axial flow pushing device. The axial flow-pushing device comprises a threaded barrel 54 and a cover 53. The threaded cylinder 54 is fixed on the rotating shaft 1 and rotates along with the rotating shaft 1, and the threaded cylinder 54 rotates in the cover body 53. One end (shown as the right end) of the cover 53 is hermetically connected to the housing 2. A thread or thread-like structure is provided on the outer surface of the threaded cylinder 54. When the threaded cylinder 54 is rotated in the housing 53, the threads exert an axial thrust (indicated by arrows) on the fluid in the housing 53, so that the pressure on the right side of the threaded cylinder 54 is lower than the pressure on the left side. The distal pressure of fluid bed 17 is communicated to the right side pressure of threaded cylinder 54 and the proximal pressure of fluid bed 17 is communicated to seal ring 4. Thus, the pressure on one side of the seal ring 4 is equal to the ambient pressure minus the superposition of the pressure variations of the axial thrust device and the swirl generating device.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. The shaft seal structure is characterized by comprising a sealing ring and at least one pressure transformation mechanism, wherein the sealing ring is arranged at the shaft hole, the sealing ring is in contact with the rotating shaft and seals a gap between the rotating shaft and the shaft hole, the pressure transformation mechanism partially or completely rotates along with the rotating shaft, pressure change is formed in the pressure transformation mechanism due to the rotation, and the pressure transformation mechanism changes the pressure difference of the fluid on two sides of the sealing ring by utilizing the pressure change.

2. The shaft seal structure according to claim 1, wherein the pressure varying mechanism includes an axial thrust device which partially or entirely rotates along with the rotating shaft, so that the fluid in the pressure varying mechanism is subjected to an axial thrust which causes a pressure change in the axial direction, that is, a pressure gradually increases in the direction of the axial thrust, and connects one end of the axial thrust device with a pressure to one side of the seal ring, and changes the fluid pressure on the side of the seal ring, thereby functioning to change the fluid pressure difference between the two sides of the seal ring.

3. The shaft seal structure of claim 2 wherein the axial displacement device includes a threaded barrel, the pressure varying mechanism further includes a housing engaged with the threaded barrel, the threaded barrel is mounted on and fixed to and rotatable with the shaft, the threaded barrel rotates within the housing, one end of the housing is connected to the housing and forms a closed end, and a threaded structure is provided on an outer surface of the threaded barrel; when the threaded cylinder rotates in the cover body, the thread-shaped structure generates axial thrust on fluid in the cover body, so that the fluid at two ends of the threaded cylinder generates pressure change in the axial direction, and the pressure at the closed end of the cover body is communicated to one side of the sealing ring, so that the effect of changing the pressure difference at two sides of the sealing ring is achieved.

4. The shaft seal structure according to claim 1, wherein the pressure varying mechanism includes a swirl flow generating device, and part or all of the swirl flow generating device rotates along with the rotating shaft, so that the fluid in the pressure varying mechanism forms a rotating fluid rotating around the rotating shaft, and the centrifugal inertia force generated by the rotating fluid causes the fluid to form a pressure change in a radial direction, i.e. the pressure of the proximal side of the rotating fluid is lower than the pressure of the distal side of the rotating fluid, and one side of the rotating fluid is communicated with one side of the seal ring, so as to change the fluid pressure of the seal ring at the side, thereby changing the fluid pressure difference between the two sides of the seal ring.

5. The shaft seal structure according to claim 4, wherein the swirling flow generating device includes a rotating body and a stationary surface, the rotating body is fixed on the rotating shaft and rotates with the rotating shaft, the stationary surface does not rotate with the rotating shaft, a fluid layer is present between the rotating body and the stationary surface, when the rotating body rotates with the rotating shaft, the fluid layer is driven by the rotating body to form a rotating fluid rotating around the rotating shaft, one side of the rotating fluid is in pressure communication with one side of the seal ring, and the function of changing the pressure difference between the two sides of the seal ring is achieved.

6. The shaft seal arrangement of claim 5 wherein said stationary surface is a surface on said pressure changing mechanism or a wall of the housing.

7. The shaft seal structure according to claim 4, 5 or 6 wherein the pressure varying structure is provided on a high pressure side of the casing, and a near-shaft side pressure of the rotating fluid is communicated to one side of the seal ring to function to reduce a pressure difference between both sides of the seal ring.

8. The shaft seal structure according to claim 5 or 6 wherein the pressure varying mechanism is disposed on the low pressure side of the casing, and further comprising a cylinder having one end fixed to the casing to form a closed end and the other end connected to the fixing surface for communicating the far axial side pressure of the rotating fluid in the cylinder to one side of the seal ring, thereby reducing the pressure difference between the two sides of the seal ring.

9. The shaft seal structure according to claim 8 wherein a flow blocking body is further provided in said cylinder, said flow blocking body being located in a communication flow path between said seal ring and said fluid layer, said flow blocking body not rotating with said rotating shaft.

10. The shaft seal structure according to claim 5 or 6 wherein stirring blades are provided on said rotor, said blades being located in a fluid layer between the rotor and the stationary surface.

11. The shaft seal structure according to claim 1, wherein the pressure varying mechanism includes at least one communicating hole communicating an internal fluid and an external fluid of the pressure varying mechanism, the fluid forming a convection flow through the communicating hole, the convection flow bringing the internal fluid and the external fluid of the pressure varying mechanism into a convection state.

12. The shaft seal structure according to claim 11 wherein said communication hole is provided at a position close to the seal ring.

13. The shaft seal structure according to claim 1, wherein the shaft seal structure comprises a plurality of pressure varying mechanisms disposed on the same side of the housing, a high pressure end of one pressure varying mechanism is communicated with a low pressure end of another pressure varying mechanism adjacent thereto, pressure changes of the plurality of pressure varying mechanisms form a series structure in a superimposed relationship, and a fluid pressure difference between both sides of the seal ring is changed by a total pressure change after the superimposed relationship.