CN112709687A

CN112709687A - Plunger piston

Info

Publication number: CN112709687A
Application number: CN201911024857.6A
Authority: CN
Inventors: 刘书豪; 陈俊宏; 刘树飞; 苏诗策
Original assignee: Chengdu Bison Technology Co ltd
Current assignee: Chengdu Bison Technology Co ltd
Priority date: 2019-10-25
Filing date: 2019-10-25
Publication date: 2021-04-27
Anticipated expiration: 2039-10-25
Also published as: CN112709687B

Abstract

The application relates to the technical field of natural gas and oil exploitation, and discloses a plunger, include: a columnar core body; the sealing gasket comprises a main gasket, the main gasket comprises a first end and a second end along the axial direction, two circumferential sides of the first end respectively extend along the circumferential direction to form a first auxiliary gasket and a second auxiliary gasket, the end face of the first auxiliary gasket, which is close to the second end, is a first contact surface, the end face of the second auxiliary gasket, which is close to the second end, is a second contact surface, an even number of sealing gaskets are arranged around the core body, and the adjacent sealing gaskets are mutually inverted along the axial direction; and a second elastic mechanism; wherein the second resilient means is configured to act on the sealing gaskets to bring the first and second contact surfaces of adjacent sealing gaskets into contact with each other. So make the fluid can't flow to the plunger top from the plunger below through the gasket clearance, improved sealing performance greatly, promote the hydrops and lift efficiency.

Description

Plunger piston

Technical Field

The application relates to the technical field of natural gas and oil exploitation, in particular to a plunger.

Background

In the development of gas or oil wells, it is necessary to lift the liquid charge at the bottom of the well to the surface in order to increase the production of gas or oil.

A plunger is provided in the related art. The periphery of the core body of the plunger is provided with a plurality of sealing gaskets, and the sealing gaskets are contacted with the inner wall of the well under the action of the elastic piece to form sealing. And the plunger descends to the bottom of the well under the well closing state, the opening state of the flow passage in the plunger or the radial contraction state of the sealing gasket. When the well is opened, when the inner flow passage of the plunger is closed or the sealing gasket is contacted with the inner wall of the well, the pressure generated by the fluid below the plunger drives the plunger to move upwards, so that the accumulated liquid above the plunger is lifted upwards, and the accumulated liquid above the plunger is discharged through the well mouth.

The problem that above-mentioned plunger exists lies in, after seal gasket radially outwards expands under the effect of elastic component, can produce the clearance between the adjacent seal gasket, at the in-process of lifting the hydrops, the hydrops of plunger top can be through above-mentioned clearance downflow, the fluid of plunger below also can be through above-mentioned clearance upflow, causes great leakage and loses, and then leads to the hydrops to lift efficiency not good.

Disclosure of Invention

Embodiments of the present application provide a plunger, it can restrict the fluid flow between the adjacent seal gasket to improve sealing performance, help improving hydrops and lift efficiency.

In order to achieve the above purpose, the embodiments of the present application adopt the following technical solutions:

a plunger, comprising: a columnar core body; the sealing gaskets comprise main gaskets, each main gasket comprises a first end and a second end along the axial direction, two circumferential sides of each first end extend along the circumferential direction to form a first auxiliary gasket and a second auxiliary gasket respectively, the end face of each first auxiliary gasket close to the second end is a first contact surface, the end face of each second auxiliary gasket close to the second end is a second contact surface, an even number of sealing gaskets are arranged around the core and are constructed to reciprocate along the radial direction, the adjacent sealing gaskets are inverted along the axial direction, and the first contact surfaces and the second contact surfaces of the adjacent sealing gaskets are opposite; a first elastic means acting on the sealing gasket and configured to give the sealing gasket a tendency to move radially outwards; and a second elastic mechanism; wherein the second resilient means is configured to act on the sealing gaskets to bring the first and second contact surfaces of adjacent sealing gaskets into contact with each other.

Further, the sealing gasket is symmetrical relative to the preset central axis.

Further, the second elastic mechanism is configured to act on the first end of the main pad to apply a force to the main pad in a direction from the first end to the second end.

Furthermore, the plunger also comprises two supporting parts fixedly arranged on the core body, the sealing gasket is positioned between the two supporting parts, and the second elastic mechanism is positioned between the first end of the main gasket and the supporting parts.

Furthermore, the supporting portion is provided with an accommodating hole, and a part of the second elastic mechanism is accommodated in the accommodating hole.

Furthermore, the second elastic mechanism comprises an elastic piece and a cushion block, the cushion block is in contact with the main gasket, and two ends of the elastic piece are respectively abutted against the supporting part and the cushion block.

Furthermore, the supporting part is annular and is sleeved on the core body; the supporting part comprises a small inner diameter section far away from the sealing gasket and a large inner diameter section close to the sealing gasket; the small inner diameter section is fixedly connected with the core body; a movable space is formed between the inner peripheral surface of the large inner diameter section and the outer peripheral surface of the core body; the end part of the axial sealing gasket extends into the movable space, and the second elastic mechanism is positioned in the movable space.

Furthermore, be provided with along the guide post of radial extension in the activity space, all set up the rectangular hole along axial extension along the both ends of axial seal gasket, the guide post runs through rectangular hole.

Further, the sealing gasket also comprises a primary sealing flange and a secondary sealing flange; the primary sealing flange and the secondary sealing flange both project radially inwardly from the inner surface of the sealing gasket, the primary sealing flange extending from the circumferential side of the first secondary gasket remote from the primary gasket along the first contact surface and the second contact surface to the circumferential side of the second secondary gasket remote from the primary gasket; the secondary sealing flange extends from one circumferential side of the primary gasket to the other circumferential side of the primary gasket; the auxiliary sealing flange is positioned on one side of the main sealing flange close to the second end and is connected with the main sealing flange; the outer peripheral surface of the core body is provided with an annular accommodating groove extending along the circumferential direction; the primary and secondary sealing flanges are radially and axially movable inserted into the annular receiving groove.

Further, the plunger further comprises an elastic sealing ring disposed in the annular receiving groove, the elastic sealing ring being configured to be radially contracted or expanded in the annular receiving groove; the primary sealing flange and the secondary sealing flange abut against the elastic sealing ring.

Further, the width of the elastic sealing ring is larger than the sum of the widths of the main sealing flange and the auxiliary sealing flange along the axial direction.

Further, the elastic sealing ring is formed by winding an elastic metal strip.

Further, two adjacent circles of the elastic sealing ring are contacted with each other along the radial direction.

The technical scheme of the application has following advantage and beneficial effect at least:

in the plunger provided by the embodiment of the application, a bent gasket gap is formed between adjacent sealing gaskets. The second elastic mechanism acts on the sealing gaskets to enable the first contact surfaces and the second contact surfaces of the adjacent sealing gaskets to be in contact with each other, and therefore gaps of the gaskets are blocked. First contact surface and second contact surface contact each other for fluid can't flow to the plunger top from the plunger below through the gasket clearance, has improved sealing performance greatly, promotes the hydrops and lifts efficiency.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments are briefly described below. It is appreciated that the following drawings depict only certain embodiments of the application and are not to be considered limiting of its scope. From these figures, other figures can be derived by those skilled in the art without inventive effort.

Fig. 1 is a schematic external structural view of a plunger according to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of an outer side structure of a sealing gasket in the plunger according to an embodiment of the present disclosure;

FIG. 3 is a schematic view of an inner side structure of a sealing gasket in the plunger according to an embodiment of the present invention;

FIG. 4 is a sectional view taken along line A-A of FIG. 1;

FIG. 5 is a schematic view of the fluid flow direction during a plunger leak, with the fluid flow direction indicated in dashed lines;

FIG. 6 is a sectional view taken along line B-B of FIG. 1;

FIG. 7 is an enlarged view at C of FIG. 4;

fig. 8 is a schematic structural diagram of an elastic sealing ring in an embodiment of the present application.

In the figure: 010-a plunger; 101-shim gap; 101 a-a first longitudinally disposed section; 101 b-a second longitudinally disposed section; 101 c-transverse section; 110-a core; 110 a-an annular receiving groove; 111-inner positioning groove; 120-a sealing gasket; 121-elongated holes; 122-central axis; 123-a master shim; 123 a-first end; 123 b-a second end; 123c — a first circumferential side; 123 d-second circumferential side; 123 e-a first secondary gasket; 123 f-a second set of shims; 123 g-first contact surface; 123 h-second contact surface; 123 i-outer positioning groove; 124-primary sealing flange; 125-secondary sealing flange; 130-a first resilient mechanism; 140-a second resilient mechanism; 141-an elastic member; 142-a cushion block; 150-a support; 151-small inner diameter section; 151 a-receiving hole; 152-a large inner diameter section; 152 a-activity space; 152 b-guide posts; 160-elastic sealing ring.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described in detail and completely with reference to the accompanying drawings. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all embodiments.

Thus, the following detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but is merely representative of some embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that, in the embodiments and the features and technical solutions in the embodiments of the present application may be combined with each other without conflict.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present application, it should be noted that the terms "upper", "lower", and the like refer to orientations or positional relationships based on those shown in the drawings, or orientations or positional relationships that are conventionally arranged when the product of the present invention is used, or orientations or positional relationships that are conventionally understood by those skilled in the art, and such terms are used for convenience of description and simplification of the description, and do not refer to or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present application.

In the description of the present application, "oil and gas well" may refer to both oil and gas wells. When the "oil and gas well" is a natural gas well, it may be a natural gas well for collecting conventional natural gas, or a natural gas well for collecting unconventional natural gas (shale gas, coal bed gas, etc.).

Example 1:

fig. 1 is a schematic view of an external structure of the plunger 010 provided in this embodiment. Fig. 2 is a schematic diagram of an outer side structure of the sealing gasket 120 in the plunger 010 according to this embodiment. Fig. 3 is a schematic view of an inner side structure of the sealing gasket 120 in the plunger 010 according to this embodiment. Fig. 4 is a sectional view taken along line a-a of fig. 1.

Referring to fig. 1 to 4, in the present embodiment, the plunger 010 includes a core 110, a sealing gasket 120, a first elastic mechanism 130, and a second elastic mechanism 140.

The core 110 is columnar, and an even number of the gasket seals 120 are arranged around the core 110. Sealing gasket 120 includes a master gasket 123. The main shim 123 has an arc shape, and the axis of the arc-shaped inner surface of the main shim 123 is parallel to the axis of the core 110. In the axial direction, the main gasket 123 includes a first end 123a and a second end 123 b. In the circumferential direction, the main pad 123 has a first circumferential side 123c and a second circumferential side 123 d. The first and second

circumferential sides

123c and 123d are end surfaces of both circumferential ends of the main pad 123. At the first end 123a of the main shim 123, a first circumferential side 123c extends circumferentially forming a first secondary shim 123 e. The length of the first sub-shim 123e in the axial direction is smaller than the length of the main shim 123. One end surface of the first sub-gasket 123e is flush with the end surface of the first end 123a of the main gasket 123, and the other end surface of the first sub-gasket 123e is a first contact surface 123 g. At the first end 123a of the main pad 123, a second circumferential side 123d extends circumferentially to form a second sub-pad 123 f. The second sub-spacer 123f has a length smaller than that of the main spacer 123 in the axial direction. One end surface of the second sub-pad 123f is flush with the end surface of the first end 123a of the main pad 123, and the other end surface of the second sub-pad 123f is a second contact surface 123 h.

In this embodiment, the number of the sealing gaskets 120 is six. Six sealing gaskets 120 are arranged around the core 110 and are configured to be capable of reciprocating in a radial direction. The adjacent sealing gaskets 120 are inverted in the axial direction, that is, in two adjacent sealing gaskets 120, the first end 123a of the main gasket 123 of one sealing gasket 120 faces upward and the second end 123b faces downward, and the first end 123a of the main gasket 123 of the other sealing gasket 120 faces downward and the second end 123b faces upward. The first contact surface 123g of one of the two adjacent sealing gaskets 120 is opposite to the second contact surface 123h of the other sealing gasket 120.

The first elastic means 130 act on the sealing gasket 120, giving the sealing gasket 120 a tendency to move radially outwards. The first elastic mechanism 130 drives the sealing gasket 120 to move radially outwards under the effect of no external force. Under the action of the radially inward external force, the sealing gasket 120 can move radially inward against the elastic force of the first elastic mechanism 130. In this embodiment, the first elastic mechanism 130 is a spring and is disposed between the sealing gasket 120 and the core 110. One end of the first elastic mechanism 130 abuts against the sealing gasket 120, and the other end of the first elastic mechanism 130 abuts against the core 110. Specifically, an outer positioning groove 123i is formed in the inner surface of the main gasket 123, and an inner positioning groove 111 facing the outer positioning groove 123i is formed in the outer circumferential surface of the core body 110. Both ends of the first elastic mechanism 130 are respectively located in the outer positioning groove 123i and the inner positioning groove 111. During the lifting process, the first elastic mechanism 130 can make the outer surface of the sealing gasket 120 contact with the inner surface of the well, so as to eliminate the gap between the sealing gasket 120 and the well.

However, when the outer surface of the sealing gasket 120 contacts the inner surface of the hoistway, a gap exists between two adjacent sealing gaskets 120, and this gap is referred to as a gasket gap 101 in this embodiment. The shim gap 101 includes a first longitudinally disposed section 101a, a second longitudinally disposed section 101b, and a laterally disposed section 101 c. The transverse segment 101c connects the first longitudinal segment 101a and the second longitudinal segment 101 b. Fluid can flow from below the plunger 010 to above the plunger 010, or from above the plunger 010 to below the plunger 010 through the spacer gap 101, and the resulting leakage will reduce the liquid loading lift efficiency. For this reason, a second elastic mechanism 140 is also provided in the present embodiment. The second elastic means 140 is configured to act on the two adjacent sealing gaskets 120 so as to make the first contact surface 123g of one sealing gasket 120 and the second contact surface 123h of the other sealing gasket 120 contact each other. Thus, the horizontal segment 101c in the gasket gap 101 is closed, and the gasket gap 101 is blocked. Fluid can not flow to the plunger 010 top from the plunger 010 below through gasket clearance 101, also can not flow to the plunger 010 below from the plunger 010 top through gasket clearance 101, has improved sealing performance greatly, promotes hydrops and lifts efficiency.

It is to be noted that the lengths of the first sub-shim 123e and the second sub-shim 123f may be different in the axial direction. In the present embodiment, for ease of manufacture and assembly, the lengths of the first sub-shim 123e and the second sub-shim 123f are the same in the axial direction. That is, the sealing gasket 120 is symmetrical with respect to the predetermined central axis 122. The predetermined central axis 122 is parallel to the axis of the core 110.

In the present embodiment, the second elastic mechanism 140 is configured to act on the first end 123a of the main pad 123, and apply a force to the main pad 123 in a direction from the first end 123a to the second end 123 b. In this way, the first contact surface 123g of one of the two adjacent gaskets 120 and the second contact surface 123h of the other gasket 120 can be brought into contact with each other.

Specifically, the second elastic mechanism 140 is arranged in the following manner. In the present embodiment, the plunger 010 further includes two supporting portions 150 fixedly provided on the core 110. The sealing gasket 120 is located between the two supporting portions 150, and the second elastic mechanism 140 is located between the first end 123a of the main gasket 123 and the supporting portions 150. The second elastic mechanism 140 is always in a compressed state, thereby applying a force to the main pad 123 in a direction from the first end 123a to the second end 123 b.

In the present embodiment, the supporting portion 150 is annular, and the core 110 is sleeved with the supporting portion 150. The support 150 includes a small inner diameter section 151 distal from the sealing gasket 120 and a large inner diameter section 152 proximal to the sealing gasket 120. The small inner diameter section 151 is fixedly coupled to the core 110 by a screw. A gap is provided between the inner peripheral surface of the large inner diameter section 152 and the outer peripheral surface of the core 110, and the gap constitutes a movable space 152 a. In the axial direction, both ends of the sealing gasket 120 protrude into the movable space 152 a. The end of the sealing gasket 120 is capable of moving radially within the active space 152 a. The support portion 150 can limit the stroke of the seal gasket 120 in the radial direction. The second elastic mechanism 140 is disposed in the movable space 152a, one end of the second elastic mechanism 140 acts on the small inner diameter section 151, and the other end of the second elastic mechanism 140 acts on the first end 123a of the main gasket 123.

Further, a guide post 152b extending along the radial direction is arranged in the movable space 152a, the two ends of the axial sealing gasket 120 are both provided with a long hole 121 extending along the axial direction, and the guide post 152b penetrates through the long hole 121. The width of the elongated hole 121 is slightly larger than the outer diameter of the guide post 152 b. This enables the seal gasket 120 to move in the radial and axial directions, and restricts the movement of the seal gasket 120 in the circumferential direction, improving the operational reliability of the plunger 010.

Further, in the present embodiment, an accommodating hole 151a is formed in an end surface of the small inner diameter section 151, and a portion of the second elastic mechanism 140 is accommodated in the accommodating hole 151 a. In this way, the second elastic mechanism 140 is better fixed.

Further, in this embodiment, the second elastic mechanism 140 includes an elastic member 141 and a cushion block 142, the cushion block 142 contacts with the main gasket 123, and two ends of the elastic member 141 respectively abut against the support portion 150 and the cushion block 142. Specifically, the elastic member 141 is completely located in the receiving hole 151a, and the pad 142 is partially located in the receiving hole 151 a. The receiving holes 151a can play a role of positioning and guiding the pad block 142.

Further, in this embodiment, the sealing gasket 120 further includes a primary sealing flange 124 and a secondary sealing flange 125. Both the primary seal flange 124 and the secondary seal flange 125 project radially inwardly from the inner surface of the sealing gasket 120, the primary seal flange 124 extending from the first secondary gasket 123e away from the circumferential side of the primary gasket 123 along the first contact surface 123g and the second contact surface 123h to the second secondary gasket 123f away from the circumferential side of the primary gasket 123; the secondary sealing flange 125 extends from one circumferential side of the primary gasket 123 to the other circumferential side of the primary gasket 123; the secondary sealing flange 125 is located on a side of the primary sealing flange 124 near the second end 123b, and the secondary sealing flange 125 is connected to the primary sealing flange 124. An annular accommodation groove 110a extending in the circumferential direction is formed in the outer circumferential surface of the core 110. The primary and

secondary seal flanges

124, 125 are radially and axially movable inserted into the annular receiving groove 110 a.

In the operation of the plunger 010 provided by this embodiment, the primary sealing flange 124 and the secondary sealing flange 125 are always inserted into the annular receiving groove 110a, so as to limit the fluid flow between the sealing gasket 120 and the core body 110, improve the sealing performance, and contribute to the improvement of the effusion lifting efficiency.

Fig. 5 is a schematic view of the flow of the fluid when the plunger 010 leaks, and the flow of the fluid is indicated by a dotted line in the figure. Referring to fig. 5, in the operation of the plunger 010, when fluid enters the first longitudinal section 101a formed between two adjacent sealing gaskets 120, the fluid can enter the annular receiving groove 110a, flow along the annular receiving groove 110a, then enter the second longitudinal section 101b of the same gasket gap 101 or other gasket gaps 101, and be discharged out of the plunger 010 through the second longitudinal section 101 b. On the contrary, when the fluid enters the second longitudinal segment 101b formed between two adjacent sealing gaskets 120, the fluid can enter the annular receiving groove 110a, flow along the annular receiving groove 110a, then enter the first longitudinal segment 101a of the same gasket gap 101 or other gasket gaps 101, and be discharged out of the plunger 010 through the first longitudinal segment 101 a. This reduces the sealing performance of the plunger 010, resulting in partial leakage.

In order to improve the above problem, the present embodiment provides the plunger 010 including the elastic seal ring 160. Fig. 6 is a sectional view taken along line B-B of fig. 1. Fig. 7 is an enlarged view of fig. 4 at C. Fig. 8 is a schematic structural view of the elastic seal ring 160. Please refer to fig. 1-8.

The elastic sealing ring 160 is disposed in the annular receiving groove 110a, and the elastic sealing ring 160 is configured to be able to contract or expand in a radial direction within the annular receiving groove 110 a. The resilient seal ring 160 has a tendency to expand radially, which enables the resilient seal ring 160 to always abut against the primary and

secondary seal flanges

124, 125. When the sealing gasket 120 moves radially inward, the elastic sealing ring 160 contracts radially under the pressing of the primary sealing flange 124 and the secondary sealing flange 125, and when the sealing gasket 120 moves radially outward, the elastic sealing ring 160 expands radially by its own elastic force. The elastic sealing ring 160 can block fluid from entering the annular accommodating groove 110a through the first longitudinally-arranged section 101a and the second longitudinally-arranged section 101b, so that the first longitudinally-arranged section 101a and the second longitudinally-arranged section 101b cannot be communicated through the annular accommodating groove 110a, fluid leakage amount of the plunger 010 in the working process is greatly reduced, sealing performance of the plunger 010 is improved, and effusion lifting efficiency can be improved.

The elastic sealing ring 160 may be a complete ring body and made of rubber, plastic or sponge having elasticity. In this embodiment, the resilient seal ring 160 is formed by a resilient metal strip wound. In particular, the resilient metal strip is made of spring steel. The elastic sealing ring 160 may be formed by winding a plurality of turns of the elastic metal strip, in this embodiment, the number of turns of the elastic metal strip is greater than 1 turn and less than 2 turns, that is, two ends of the elastic metal strip are overlapped with each other to form the elastic sealing ring 160. Further, adjacent two rings of the elastic sealing ring 160 contact each other, so that fluid can be prevented from flowing along a space between the adjacent two rings of the elastic sealing ring 160, and the sealing performance can be improved.

In this embodiment, the width of the resilient seal ring 160 is greater than the sum of the widths of the primary seal flange 124 and the secondary seal flange 125 in the axial direction. Thus, the fluid flow between the sealing gasket 120 and the core 110 can be further limited, the sealing performance is improved, and the liquid lifting efficiency is improved. Specifically, a clearance is inevitably provided between the side surface of the primary seal flange 124 and the side surface of the annular receiving groove 110a, and a clearance is inevitably provided between the side surface of the secondary seal flange 125 and the side surface of the annular receiving groove 110 a. Fluid can enter the annular receiving groove 110a through a gap between the side surface of the primary seal flange 124 and the side surface of the annular receiving groove 110a, and then flow out of the annular receiving groove 110a through a gap between the side surface of the secondary seal flange 125 and the side surface of the annular receiving groove 110 a. Conversely, the fluid can enter the annular receiving groove 110a through the gap between the side surface of the secondary seal flange 125 and the side surface of the annular receiving groove 110a, and then flow out of the annular receiving groove 110a through the gap between the side surface of the primary seal flange 124 and the side surface of the annular receiving groove 110 a. Since the width of the elastic sealing ring 160 is greater than the sum of the widths of the primary sealing flange 124 and the secondary sealing flange 125, it becomes difficult for fluid to enter the annular receiving groove 110a, thereby improving sealing performance and contributing to the improvement of effusion lifting efficiency.

The above description is only a few examples of the present application and is not intended to limit the present application, and those skilled in the art will appreciate that various modifications and variations can be made in the present application. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A plunger, comprising:

a columnar core body;

a sealing gasket comprising a main gasket, the main gasket comprises a first end and a second end along the axial direction, two circumferential sides of the first end extend along the circumferential direction to form a first auxiliary gasket and a second auxiliary gasket respectively, the end surface of the first auxiliary gasket close to the second end is a first contact surface, the end surface of the second gasket close to the second end is a second contact surface, an even number of the sealing gaskets are arranged around the core body and are constructed to reciprocate along the radial direction, the adjacent sealing gaskets are mutually inverted along the axial direction, and the first contact surface and the second contact surface of the adjacent sealing gaskets are opposite;

a first elastic means acting on said sealing gasket and configured to give said sealing gasket a tendency to move radially outwards; and

a second elastic mechanism;

wherein the second resilient mechanism is configured to act on the sealing gasket to bring the first and second contact surfaces of adjacent sealing gaskets into contact with each other.

2. The plunger of claim 1, wherein:

the sealing gasket is symmetrical relative to a preset central axis.

3. The plunger of claim 1, wherein:

the second elastic mechanism is configured to act on the first end of the main pad to apply a force to the main pad in a direction from the first end to the second end.

4. The plunger of claim 3, wherein:

the plunger further comprises two supporting parts fixedly arranged on the core body, the sealing gasket is positioned between the two supporting parts, and the second elastic mechanism is positioned between the first end of the main gasket and the supporting parts.

5. The plunger of claim 4, wherein:

an accommodating hole is formed in the supporting portion, and a part of the second elastic mechanism is accommodated in the accommodating hole.

6. The plunger of claim 4, wherein:

the second elastic mechanism comprises an elastic piece and a cushion block, the cushion block is in contact with the main gasket, and two ends of the elastic piece are respectively abutted against the supporting part and the cushion block.

7. The plunger of claim 4, wherein:

the supporting part is annular and is sleeved on the core body;

the supporting part comprises a small inner diameter section far away from the sealing gasket and a large inner diameter section close to the sealing gasket; the small inner diameter section is fixedly connected with the core body; a movable space is formed between the inner peripheral surface of the large inner diameter section and the outer peripheral surface of the core body; the end part of the sealing gasket extends into the movable space along the axial direction, and the second elastic mechanism is positioned in the movable space.

8. The plunger of claim 7, wherein:

the movable space is internally provided with guide columns extending along the radial direction, the two ends of the sealing gasket along the axial direction are both provided with strip holes extending along the axial direction, and the guide columns penetrate through the strip holes.

9. The plunger of claim 1, wherein:

the seal gasket further comprises a primary seal flange and a secondary seal flange; the primary and secondary sealing flanges each projecting radially inwardly from an inner surface of the sealing gasket, the primary sealing flange extending from a circumferential side of the first secondary gasket away from the primary gasket along the first and second contact surfaces to a circumferential side of the second secondary gasket away from the primary gasket; the secondary sealing flange extending from one circumferential side of the primary gasket to the other circumferential side of the primary gasket; the secondary sealing flange is positioned on one side of the primary sealing flange close to the second end, and the secondary sealing flange is connected with the primary sealing flange;

the outer peripheral surface of the core body is provided with an annular accommodating groove extending along the circumferential direction;

the primary seal flange and the secondary seal flange are radially and axially movably inserted into the annular receiving groove.

10. The plunger of claim 9, wherein:

the plunger further includes an elastic sealing ring disposed within the annular receiving groove, the elastic sealing ring configured to be radially contractible or expandable within the annular receiving groove; the main sealing flange and the auxiliary sealing flange are abutted against the elastic sealing ring.

11. The plunger of claim 10, wherein:

in the axial direction, the width of the elastic sealing ring is greater than the sum of the widths of the main sealing flange and the auxiliary sealing flange.

12. The plunger of claim 10, wherein:

the elastic sealing ring is formed by winding an elastic metal strip.

13. The plunger of claim 12, wherein:

in the radial direction, two adjacent circles of the elastic sealing ring are in contact with each other.