CN111219324B

CN111219324B - Plunger piston

Info

Publication number: CN111219324B
Application number: CN201811416576.0A
Authority: CN
Inventors: 胡顺渠; 侯治民; 陈晨; 刘涛; 刘通
Original assignee: China Petroleum and Chemical Corp; Sinopec Southwest Oil and Gas Co
Current assignee: China Petroleum and Chemical Corp; Sinopec Southwest Oil and Gas Co
Priority date: 2018-11-26
Filing date: 2018-11-26
Publication date: 2022-01-21
Anticipated expiration: 2038-11-26
Also published as: CN111219324A

Abstract

The invention relates to a plunger, which comprises a fishing neck; the cylindrical upper outer sleeve is arranged at the lower end of the fishing neck and can axially move relative to the fishing neck, and a first communication hole which is communicated with the inside and the outside is formed in the wall of the upper outer sleeve; the lower sleeve is communicated with the lower end of the upper sleeve and can move axially relative to the upper sleeve, and a second communication hole which is communicated with the inside and the outside is formed in the wall of the lower sleeve; one end sets up on the outer wall of last overcoat and the packing element subassembly of the other end setting on overcoat down, the packing element subassembly has the packing element, under the first state, the inner chamber department of second intercommunicating pore and first intercommunicating pore overcoat is ending and the packing element atress inflation under, under the second state, the inner chamber intercommunication and the packing element of second intercommunicating pore and first intercommunicating pore overcoat are contract under, this plunger can be applicable to reducing oil pipe, has improved its application range, is particularly useful for deep and ultra-deep oil gas well.

Description

Plunger piston

Technical Field

The invention relates to the technical field of gas production tools, in particular to a plunger.

Background

The plunger gas lift technology is characterized in that a plunger is used as a mechanical interface between gas and liquid, the plunger is pushed by the self energy of a gas well to lift liquid periodically in an oil pipe, gas can be effectively prevented from jumping upwards and liquid can fall back, the liquid slippage effect is reduced, the drainage assisting effect is achieved, and the intermittent gas lift efficiency is improved.

At present, the exploration and development of oil and gas wells are continuously developed towards deep layers and ultra-deep layers, but the plunger in the prior art cannot freely slide in the variable-diameter combined tubing string and is difficult to adapt to deep wells or ultra-deep wells. Therefore, the plunger is required to be invented to adapt to the variable-diameter combined oil pipe.

Disclosure of Invention

In view of some or all of the above problems, the present invention provides a plunger. The plunger can effectively plug the inner cavity of the oil pipe in the moving process so as to improve the water drainage and gas production effects of the plunger. In addition, the plunger piston can be suitable for variable-diameter oil pipes, improves the application range of the plunger piston, and is particularly suitable for deep and ultra-deep oil and gas wells.

According to the present invention, there is provided a plunger comprising:

the neck of the fishing rod is fished,

a cylindrical upper outer sleeve which is arranged at the lower end of the fishing neck and can move axially relative to the fishing neck, a first communicating hole which is communicated with the inside and the outside is arranged on the wall of the upper outer sleeve,

a cylindrical lower jacket which is arranged at the lower end of the upper jacket in a communicating manner and can move axially relative to the upper jacket, a second communicating hole which is communicated with the inside and the outside is arranged on the wall of the lower jacket,

a rubber cylinder component with one end arranged on the outer wall of the upper outer sleeve and the other end arranged on the lower outer sleeve, the rubber cylinder component is provided with a rubber cylinder,

under the first state, the second communicating hole and the first communicating hole are stopped at the inner cavity of the lower outer sleeve, and the rubber cylinder is stressed to expand, and under the second state, the second communicating hole and the first communicating hole are communicated at the inner cavity of the lower outer sleeve, and the rubber cylinder retracts.

In one embodiment, a first step surface is provided on a wall of the upper outer jacket such that an outer diameter of a lower end of the upper outer jacket is smaller than an outer diameter of an upper end, the lower outer jacket is fitted over the upper outer jacket wall at a lower end of the first step surface, and a first damping mechanism is provided between the upper outer jacket and the lower outer jacket.

In one embodiment, the first damping mechanism has a ratchet ring embedded on the outer wall of the upper outer sleeve and ratchet teeth disposed inside the lower outer sleeve.

In one embodiment, a cylindrical spring sleeve is arranged between the fishing neck and the upper outer sleeve, the upper end of the spring sleeve is movably sleeved on the outer wall of the fishing neck, the lower end of the spring sleeve is fixedly connected with the upper outer sleeve, and an elastic piece is arranged between the spring sleeve and the fishing neck in the axial direction.

In one embodiment, a sealing seat positioned between the rubber cylinder component and the second communication hole is arranged on the inner wall of the lower outer sleeve, a sealing hole axially communicated is arranged on the sealing seat,

a cylindrical guide head is fixedly arranged at the lower end of the lower outer sleeve,

a sealing rod is arranged in the inner cavity of the lower outer sleeve, the sealing rod penetrates through the guide head to extend downwards, the sealing rod can axially move relative to the sealing seat, the sealing head at the upper end of the sealing rod can be matched with the sealing hole to seal the sealing hole,

a push rod fixedly connected with the fishing neck is arranged in the inner cavity of the upper outer sleeve.

In one embodiment, a stop assembly for defining the axial position of the seal rod is disposed on the inner wall of the lower housing, and a second damping mechanism is disposed between the stop assembly and the seal rod.

In one embodiment, the seal bore is configured with a cylindrical upper end and a frustoconical lower end, and the seal head is configured to mate with the seal bore.

In one embodiment, a radial projection that can abut on the upper end face of the sealing bore is provided on the lower end outer wall of the push rod.

In one embodiment, a drain hole is provided at the lower end of the guide head.

In one embodiment, a bypass hole is provided in at least one of the upper and lower outer casings in communication with the inside of the glue cartridge assembly.

Compared with the prior art, the invention has the advantages that: the plunger is provided with the rubber sleeve assembly, and after the rubber sleeve of the rubber sleeve assembly expands, the annular space between the oil pipe and the plunger can be blocked, so that the inner cavity of the oil pipe can be effectively blocked, and the drainage and gas production effects are improved. Meanwhile, the rubber sleeve has certain elasticity, so that the rubber sleeve can adapt to oil pipes with different diameters in the process that the plunger is subjected to pressure difference to move upwards, and the application range of the rubber sleeve is enlarged.

Drawings

The invention will be described in more detail hereinafter on the basis of embodiments and with reference to the accompanying drawings. Wherein:

FIG. 1 schematically illustrates an initial state diagram of a plunger according to one embodiment of the present invention;

FIG. 2 schematically illustrates a view of the plunger at the bottom dead center with the seal housing engaged with the seal rod according to one embodiment of the present invention;

FIG. 3 schematically illustrates a diagram of a state of expansion of a rubber cartridge at bottom dead center of a plunger according to an embodiment of the present invention;

FIG. 4 schematically illustrates a diagram of the plunger ascending in the small oil pipe according to an embodiment of the present invention;

FIG. 5 schematically illustrates a view of a plunger ascending in a large oil tube according to an embodiment of the present invention;

FIG. 6 schematically illustrates a state view of the plunger at top dead center and contacting the seal seat and the seal rod according to an embodiment of the present invention;

in the drawings, like parts are provided with like reference numerals. The drawings are not to scale.

Detailed Description

The invention will be further explained with reference to the drawings.

Fig. 1 shows a plunger 100 according to the present invention. As shown in FIG. 1, the plunger 100 includes a fishing neck 1, an upper housing 5, a lower housing 9, and a glue barrel assembly 30. Wherein, the fishing neck 1 is columnar. The upper outer sleeve 5 is cylindrical, is arranged at the lower end of the fishing neck 1 and can axially move relative to the fishing neck 1. A first communication hole 103 communicating inside and outside is provided on the wall of the upper outer jacket 5. The lower outer sleeve 9 is cylindrical and is arranged at the lower end of the upper outer sleeve 5, and the inner cavity of the lower outer sleeve is communicated with the inner cavity of the upper outer sleeve 5. Also, the lower outer jacket 9 is configured to be axially movable relative to the upper outer jacket 5. A second communication hole 110 communicating inside and outside is provided in the wall of the lower outer jacket 9. One end of the glue cartridge assembly 30 is disposed on the outer wall of the upper housing 5 and the other end is disposed on the outer wall of the lower housing 9. During the relative movement of the upper and lower

outer casings

5, 9, to actuate the expansion and retraction of the glue cartridge 7 of the glue cartridge assembly 30.

During the downward movement of the plunger 100, the first communication hole 103 and the second communication hole 110 are communicated through the inner cavities of the upper outer sleeve 5 and the lower outer sleeve 9, and at the moment, the rubber sleeve 7 is in a retraction state so as not to influence the downward movement of the plunger 100. After the plunger 100 moves down to the bottom dead center, the upper outer sleeve 5 and the lower outer sleeve 9 relatively move to expand the rubber tube 7. The above movement also blocks the communication of the first communication hole 103 and the second communication hole 110. In this condition, the packing element 7 seals off the annulus between the plunger 100 and the tubing. After a pressure difference is formed above and below the rubber sleeve 7, the rubber sleeve 7 is further compressed on one hand, so that the blocking effect of the rubber sleeve 7 on an annular space between the plunger 100 and the oil pipe is increased; on the other hand, under the action of the pressure difference generated by the production well, the plunger 100 goes up against the self-gravity and the friction force of the rubber sleeve 7 and the oil pipe. Due to the elasticity of the rubber sleeve 7, the diameter range of the applicable oil pipe is wide, and the sealing of the oil pipes with different inner diameters is easily realized, so that the water drainage and gas production in a deep well or an ultra-deep well are further realized. The "first state" and "second state" are described herein to distinguish between different operating states of the plunger 100 at different times and during different movements. That is, when the first communication hole 103 and the second communication hole 110 communicate through the inner cavities of the upper outer sleeve 5 and the lower outer sleeve 9, and the cartridge 7 is in the retracted state, the plunger 100 is in the second state. When the first communication hole 103 and the second communication hole 110 are closed and the cartridge 7 is in the expanded state, the plunger 100 is in the first state.

In one embodiment, the first step surface 120 is provided on the wall of the upper outer jacket 5 such that the outer diameter of the lower end of the upper outer jacket 5 is smaller than the outer diameter of the upper end. Meanwhile, the lower shell 9 is fitted over the wall of the upper shell 5 below the first step surface 120. Under the action of force, the upper and

lower casings

5, 9 can move axially relative to each other to actuate the expansion of the glue cartridge 7. In addition, a first damping mechanism is provided between the upper outer jacket 5 and the lower outer jacket 9 to define an axial position therebetween. Preferably, the first damping mechanism has a first ratchet ring 8 embedded on the outer wall of the upper outer sleeve 5 and first ratchet teeth 31 provided on the inner wall of the lower outer sleeve.

Specifically, the glue cylinder assembly 30 includes a glue cylinder 7 and metal members 6 disposed at upper and lower ends of the glue cylinder 7. The metal member 6 serves to protect both ends of the rubber tube 7 and to conveniently dispose the rubber tube 7 on other components. The metal member 6 is respectively provided on the upper and lower

outer casings

5 and 9 by means of the lock nut 10 so that both ends of the packing cylinder 7 are respectively provided on the upper and lower

outer casings

5 and 9. The structure is simple and easy to realize.

In one embodiment, a cylindrical spring sleeve 2 is provided between the fishing neck 1 and the upper outer sleeve 5. The upper end of the spring sleeve 2 is movably sleeved on the outer wall of the fishing neck 1, and the lower end is fixedly connected with the upper outer sleeve 5. In addition, an elastic element 3 is arranged between the spring sleeve 2 and the fishing neck 1 in the axial direction. During the upward movement of the spring housing 2 relative to the fishing neck 1, the elastic element 3 is compressed.

A sealing seat 11 is arranged on the inner wall of the lower outer sleeve 9. The seal holder 11 is located between the cartridge assembly 30 and the second communication hole 110. The seal seat 11 is provided with a seal hole 109 which is axially communicated. A cylindrical guide head 17 is fixedly provided at the lower end of the lower jacket 9. A sealing rod 13 is arranged in the inner cavity of the lower outer sleeve 9. The sealing rod 13 extends downwards through the guide head 17. At the same time, the sealing rod 13 can move axially relative to the sealing seat 11, and the upper sealing head 111 of the sealing rod 13 can cooperate with the sealing hole 109 to close or open the sealing hole 109, so that the second communication hole 110 communicates with or closes off the first communication hole 103 at the inner cavity of the lower outer sleeve 9. A push rod 4 is arranged in the inner cavity of the upper outer sleeve 5. The upper end of the push rod 4 is fixedly connected with the fishing neck 1, and the lower end extends downwards in the inner cavity of the upper outer sleeve 5.

A limiting step 102 is formed at the upper end of the push rod 4 to cooperate with the lower end surface of the spring housing 2 to realize axial limiting. In particular, the spring housing 2 has a radially extending projection 32 to extend radially between the stop step 102 and the lower end face of the fishing neck 1. The elastic element 3 is inserted into the space formed by the outer wall of the push rod 4, the inner wall of the spring sleeve 2, the projection 32 and the lower end face of the fishing neck 1. Preferably, the elastic member 3 is a spring, and the upper end of the spring abuts against the lower end surface of the fishing neck 1, and the lower end abuts against the upper end surface of the protrusion 32.

During the process that the push rod 4 moves downwards relative to the sealing seat 11 along with the fishing neck 1, the lower end of the push rod 4 can penetrate into the sealing hole 109 of the sealing seat 11 to push the sealing rod 13 to move downwards, so that the matching between the sealing rod 13 and the sealing seat 11 is released. Preferably, a radial projection 107 is formed on the outer wall of the push rod 4 near the lower end. During the downward movement of the push rod 4, the projection 107 can abut on the upper end surface of the seal hole 109, thereby restricting the push rod 4 from moving further downward. On the other hand, the push rod 4 abuts against the seal seat 11 to ensure that the seal seat 11 and the lower outer sleeve 9 cannot move upward relative to the push rod 4, and the upper outer sleeve 5 moves upward relative to the lower outer sleeve 9 in the axial direction to retract the rubber tube 7 (described in detail later).

Preferably, the seal bore 109 is configured with a cylindrical upper end and a frustoconical lower end. Meanwhile, the sealing head 111 of the sealing rod 13 is structurally matched with the sealing hole 109 to achieve a good sealing effect.

A limiting component 33 is arranged on the inner wall of the lower outer sleeve 9. The limiting component 33 can be in clamping fit with the sealing rod 13 to limit the axial position of the sealing rod 13 and prevent the sealing rod 13 from moving downwards further. And a second damping mechanism is provided between the stop assembly 33 and the sealing rod 13 for locking the axial position of the sealing rod 13. Preferably, the stop assembly 33 includes a first stop 14 embedded in the inner wall of the lower outer sleeve 9 and a second stop 16 axially abutting against the first stop 14. In the radial direction, the first stopper 14 projects radially inward so that the upper end seal head 111 of the seal rod 13 overlaps the upper end face of the first stopper 14 to define the axial position of the seal rod 13. A groove is formed at the first stopper 14 and the second stopper 16 for fitting the second ratchet ring 15 included in the second damping mechanism. A second ratchet 35 included in the second damping mechanism is provided on the outer wall of the sealing rod 13 to be engaged with the second ratchet ring 15.

It should be noted that the first stopper 14 and the second stopper 16 may be a split structure or an integral structure, and are shown as a split structure in fig. 1. Of course, this split structure facilitates the installation of the second ratchet ring 15. In addition, the stop assembly 33 can be snapped onto the inner wall of the lower casing 9 and also between the lower casing 9 and the guide head 17, as is shown in fig. 1 as being snapped between the lower casing 9 and the guide head 17. Any construction that can fix the axial position of the stopper assembly 33 so as not to move axially relative to the lower outer jacket 9 falls within the scope of the present application. In addition, the lower outer sleeve 9 can be constructed in a split structure in the axial direction, so that the production and installation are convenient. As shown in fig. 1, the lower outer jacket 9 is broken at the sealing seat 11 and is constructed in a split structure.

The sealing rod 13 extends outwards through the guide head 17, so that after the sealing rod 13 contacts the bottom dead center, the sealing rod 13 moves upwards relative to the guide head 17, thereby engaging with the sealing seat 11 and closing off the sealing hole 109.

A discharge hole 36 is provided at the lower end of the guide head 17. The discharge hole 36 is used to communicate the space formed by the guide head 17, the sealing rod 13 and the stopper member 33. During axial movement of sealing rod 13 relative to guide head 17, fluid in the space formed by guide head 17, sealing rod 13 and stop assembly 33 may be expelled through vent hole 36 without impeding the movement of sealing rod 13.

At least one of the upper and lower

outer sleeves

5, 9 is provided with an axial bypass hole 104 communicating with the inside of the rubber cylinder assembly 30. During expansion of the glue cartridge 7, fluid can enter the space formed by the upper outer sleeve 5, the lower outer sleeve 9 and the glue cartridge 7 through the bypass holes 104 to fill the space. During retraction of the glue cartridge 7, fluid can enter the inner cavities of the upper outer sleeve 5 and the lower outer sleeve 9 through the bypass holes 104, so that the glue cartridge 7 can be quickly responded to and retracted.

Wherein, the teeth on the second ratchet ring 15 and the second ratchet 35, and the teeth on the first ratchet ring 8 and the first ratchet 31 are bidirectional 45-degree teeth (the two wall surfaces of the teeth and the radial dimension are both 45 degrees), thereby realizing locking and unlocking.

The operation of the plunger 100 is described in detail below with reference to fig. 1 to 6.

First, the plunger 100 is plunged into the well. Under its own weight, the plunger 100 moves downward. During the fall, the glue cartridge 7 is in a retracted state as shown in fig. 1. Meanwhile, the inner cavity of the plunger 100 communicates with the outside through the first communication hole 103, the seal hole 109, and the second communication hole 110. As the plunger 100 is lowered, fluid in the tubing flows up through the annulus between the plunger 100 and the tubing and the interior cavity of the plunger 100.

The plunger 100 continues to fall and reaches the bottom dead center position. The sealing rod 13 of the plunger 100 first contacts the anchor fishing neck 18, and as the other parts of the plunger 100, except for the sealing rod 13, continue to descend, the sealing rod 13 ascends relative to the sealing seat 11. During the upward movement of the sealing rod 13 relative to the sealing seat 11, the sealing head 111 engages the sealing hole 109, thereby separating the inner cavity of the plunger 100 up and down, as shown in fig. 2. That is, the communication of the first communication hole 103 and the second communication hole 110 is blocked in the inner cavity of the plunger 100. At the same time, the second damping mechanism operates to define the axial position of the sealing rod 13. At this time, the guide head 17 is in contact with the anchor fishing neck 18, and the guide head 17 and the lower outer jacket 9 are axially immovable with respect to the anchor fishing neck 18. Under the action of inertia, the upper outer sleeve 5 drives the spring sleeve 2, the fishing neck 1, the push rod 4 and other parts to move downwards relative to the fishing neck 18 of the anchor. In this condition, the glue cartridge 7 is expanded by the axial force due to the downward movement of the upper outer jacket 5 relative to the lower outer jacket 9, as shown in fig. 3. After the rubber sleeve 7 is expanded under force, the annular space between the plunger 100 and the oil pipe is sealed. At this time, the first damping mechanism acts to prevent the cartridge 7 from retracting.

Because the rubber cylinder 7 is in an expansion state, a pressure difference is formed above and below the rubber cylinder 7 in the well production process, and the rubber cylinder 7 is further compressed. After the above-mentioned pressure difference reaches a certain level, the plunger 100 is pushed up by the external force applied to the plunger 100 against the gravity and friction of the plunger 100, as shown in fig. 4 and 5. Due to the elasticity of the rubber sleeve 7, the plunger 100 can adapt to different oil pipe diameters. For example, fig. 4 shows the plunger 100 in a raised state within a small oil pipe. Fig. 5 shows a state where the plunger 100 ascends in the large oil pipe. Therefore, the plunger 100 can be matched with oil pipes with different pipe inner diameters, has a wide application range, and is particularly suitable for deep wells or ultra-deep wells.

The plunger 100 continues to rise and reaches a top dead center position. When the fishing neck 1 of the plunger 100 contacts the upper positioning rod 21, the fishing neck 1 is not moved relative to the upper positioning rod 21. In addition to the fishing neck 1 and the push rod 4, other components of the plunger 100 continue upward. The push rod 4 moves downwards relative to the sealing seat 11. The push rod 4 passes through the seal hole 109 to apply force to the seal rod 13. Under force, the second ratchet ring 15 is unlocked from the second ratchet 35 and the sealing rod 13 is caused to descend relative to the sealing seat 11. At this time, the engagement of the seal holder 11 with the seal rod 13 is released, so that the second communication hole 110, the seal hole 109 and the first communication hole 103 communicate through the inner cavity of the plunger 100, as shown in fig. 6. The fishing neck 1 is fixedly connected with the push rod 4 to ensure that the push rod 4 is immovable relative to the upper positioning rod 21. On the other hand, since the projection 107 of the plunger 4 abuts against the upper end surface of the seal hole 109, the seal holder 11 is also immovable with respect to the upper positioning rod 21. The seal housing 11 in turn immobilizes the lower jacket 9 relative to the upper retaining rod 21. However, under the action of the inertial force, the upper outer sleeve 5 and the spring housing 2 continue to compress the elastic member 3 to move upward. During the upward movement of the upper outer jacket 5 relative to the lower outer jacket 9, the interaction of the first ratchet ring 8 and the first ratchet 31 is released. The cartridge 7 is thereby retracted and the plunger 100 returns to the initial state shown in figure 1.

Under the action of gravity, the plunger 100 moves down and repeats the above drainage and gas production operations.

In the present application, the orientation terms "upper" and "lower" are used with reference to the actual operating orientation of the plunger 100.

While the invention has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In particular, the technical features mentioned in the embodiments can be combined in any way as long as there is no structural conflict. It is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A plunger, comprising:

the neck of the fishing rod is fished,

a cylindrical upper outer sleeve which is arranged at the lower end of the fishing neck and can axially move relative to the fishing neck, a first communication hole which is communicated with the inside and the outside is arranged on the wall of the upper outer sleeve,

a rubber cylinder component with one end arranged on the outer wall of the upper outer sleeve and the other end arranged on the lower outer sleeve, wherein the rubber cylinder component is provided with a rubber cylinder,

wherein, a sealing seat positioned between the rubber cylinder component and the second communication hole is arranged on the inner wall of the lower outer sleeve, a sealing hole which is axially communicated is arranged on the sealing seat,

a sealing rod which can move relative to the sealing seat along the axial direction is arranged in the inner cavity of the lower outer sleeve, a sealing head which can close the sealing hole so as to cut off the communication between the first communication hole and the second communication hole is arranged at the upper end of the sealing rod,

the lower end of the lower outer sleeve is also provided with a guide head, the sealing rod passes through the guide head and extends downwards,

a push rod which is fixedly connected with the fishing neck and can move along the axial direction under the driving of the fishing neck is arranged in the inner cavity of the upper outer sleeve,

in the first state, the sealing head can stretch into and seal the sealing hole to enable the second communication hole and the first communication hole to be stopped at the inner cavity of the lower outer sleeve, so that fluid flowing into the first communication hole enters the rubber sleeve and supports the rubber sleeve to expand under stress, and in the second state, the push rod can push the sealing head out of the sealing hole to enable the second communication hole and the first communication hole to be communicated with each other in the inner cavity of the lower outer sleeve, so that the fluid flowing into the first communication hole flows out of the second communication hole, and the rubber sleeve retracts.

2. The plunger of claim 1, wherein a first step surface is provided on a wall of the upper outer jacket such that an outer diameter of a lower end of the upper outer jacket is smaller than an outer diameter of an upper end, the lower outer jacket is fitted over the upper outer jacket wall at a lower end of the first step surface, and a first damping mechanism is provided between the upper outer jacket and the lower outer jacket.

3. The plunger of claim 2 wherein said first damping mechanism has a ratchet ring embedded on an outer wall of said upper outer sleeve and ratchet teeth disposed inside said lower outer sleeve.

4. The plunger of any one of claims 1 to 3, wherein a cylindrical spring sleeve is arranged between the fishing neck and the upper outer sleeve, the upper end of the spring sleeve is movably sleeved on the outer wall of the fishing neck, the lower end of the spring sleeve is fixedly connected with the upper outer sleeve, and an elastic piece is arranged between the spring sleeve and the fishing neck in the axial direction.

5. The plunger of any one of claims 1 to 3, wherein a stop assembly is provided on the inner wall of the lower casing for defining the axial position of the sealing rod, and a second damping mechanism is provided between the stop assembly and the sealing rod.

6. The plunger of any one of claims 1-3, wherein the sealing bore is configured with a cylindrical upper end and a frustoconical lower end, and wherein the sealing head is in structural engagement with the sealing bore.

7. The plunger according to any one of claims 1 to 3, wherein a radial projection capable of abutting on an upper end face of the sealing bore is provided on a lower end outer wall of the push rod.

8. A plunger according to any one of claims 1 to 3, characterised in that a discharge hole is provided at the lower end of the guide head.

9. The plunger of any one of claims 1-3, wherein a bypass orifice is provided in at least one of the upper and lower outer jackets in communication with the inside of the glue cartridge assembly.