End sealing and cooling structure for plunger

Abstract

The invention provides an end sealing and cooling structure for a plunger. The end sealing and cooling structure for the plunger comprises a sealing sleeve and the plunger arranged on the core portion of the sealing sleeve in a penetrating mode. A threaded sleeve, a water jacket, a three-stage sealing structure and a guide sleeve are sequentially arranged between the plunger and the sealing sleeve; annular cooling flow channels are formed between the water jacket and the plunger and between the water jacket and the sealing sleeve respectively. The annular cooling flow channels are communicated with a cooling medium inlet and a cooling medium outlet in the sealing sleeve. A pressure detection device is arranged on the quick-change connector at the cooling medium outlet; the three-stage sealing structure comprises three UN sealing rings and three supporting rings, and the UN sealing rings and the supporting rings are arranged at intervals; an annular groove is formed in the UN sealing ring, an annular protrusion is arranged on the supporting ring, and the annular protrusion is connected with the annular groove in an inserted mode. The problems that an existing sealing structure is prone to failure in the high-temperature and high-pressure environment, and sealing failure cannot be found in time are solved.

Description

Technical Field

[0001] This invention belongs to the field of plunger pump technology, and specifically relates to an end-sealing cooling structure for a plunger. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] In grouting pumps, high-pressure plunger pumps, fuel injection systems, and hydraulic power units, the periodic changes in the working chamber volume are used to achieve fluid intake, compression, and discharge, thereby enabling the plunger to perform high-frequency reciprocating motion within a sealed cavity. During this process, the plunger end not only withstands periodically alternating high-pressure impacts in each reciprocating stroke but also maintains high-speed relative motion with the sealing element or cylinder liner inner wall. This coupling of mechanics and motion presents three core challenges for end seals: the sustained reliability of dynamic seals, resistance to extrusion under extreme pressure, and long service life under low friction and wear.

[0004] Traditional sealing structures, such as single O-rings, stuffing boxes, or metal sealing rings, often struggle to balance sealing performance and service life under complex dynamic high-pressure conditions. Especially in high-temperature and high-pressure environments, the sealing rings are subjected to excessive stress, which can easily lead to failure. In addition, sealing structures cannot monitor for leaks in real time, making it difficult to detect leaks of high-temperature and high-pressure media or early failures of the sealing structure, posing significant safety hazards. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides an end-sealing cooling structure for plungers, which solves the problems of existing sealing structures being prone to failure in high-temperature and high-pressure environments and the inability to detect sealing failures in a timely manner.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: This invention provides an end-sealing cooling structure for a plunger, comprising: a sealing sleeve and a plunger penetrating the core of the sealing sleeve, wherein the sidewall of the plunger is provided with microstructures; a threaded sleeve, a water jacket, a three-stage sealing structure, and a guide sleeve are sequentially arranged between the plunger and the sealing sleeve; the sealing sleeve is provided with three stages of stepped holes, namely a first-stage hole, a second-stage hole, and a third-stage hole with successively decreasing diameters; the threaded sleeve is threadedly installed in the first-stage hole, the water jacket, the three-stage sealing structure, and the guide sleeve are installed in the second-stage hole, and the plunger is clearance-fitted with the third-stage hole; the water jacket forms an annular cooling channel with the plunger and the sealing sleeve respectively, and the annular cooling channel is connected to a cooling medium inlet and a cooling medium outlet on the sealing sleeve; a pressure detection device is provided on the quick-connect fitting at the cooling medium outlet; The three-stage sealing structure includes three UN sealing rings and three support rings, with the UN sealing rings and support rings arranged at intervals, and each UN sealing ring corresponding to one support ring; the UN sealing ring is provided with an annular groove, and the support ring is provided with an annular protrusion, the annular protrusion is inserted into the annular groove, and expands the UN sealing ring, so that the UN sealing ring is pressed tightly with the plunger and the sealing sleeve to form a seal.

[0007] As a further implementation, the annular groove is disposed on one side of the UN sealing ring, and the annular protrusion is disposed on one side of the support ring. The cross-sectional shapes of the annular groove and the annular protrusion are wedge-shaped and trapezoidal, respectively, and the cross-sectional dimension of the annular groove is larger than that of the annular protrusion.

[0008] As a further implementation, the pipe joints are a cooling medium inlet joint and a cooling medium outlet joint, respectively; the included angle between the axes of the cooling medium inlet joint and the cooling medium outlet joint is less than or equal to 60°.

[0009] As a further implementation, a first O-ring and a second O-ring are provided on the end face of one end of the third-level hole of the sealing sleeve, wherein the curvature of the first O-ring is greater than the curvature of the second O-ring.

[0010] As a further implementation, a U-shaped sealing ring is provided on the side of the water jacket near the plunger, with the notch of the U-shaped sealing ring facing the cooling flow channel.

[0011] As a further implementation, a third O-ring is provided on the side of the water jacket near the sealing sleeve, and both the U-ring and the third O-ring are arranged at the end of the water jacket near the threaded sleeve.

[0012] As a further implementation, the sealing sleeve is made of carbon structural steel and has undergone quenching and tempering heat treatment.

[0013] As a further implementation, quick-connect couplings are installed at both the cooling medium inlet and the cooling medium outlet, and combination washers are installed on the quick-connect couplings.

[0014] As a further implementation, the pressure detection device is a pressure sensor.

[0015] As a further implementation, the support ring is made of an engineering plastic with self-lubricating properties and a hardness higher than that of the UN sealing ring, so that the UN sealing ring can effectively fill the radial gap between the plunger and the sealing sleeve.

[0016] Compared with the prior art, the advantages and positive effects of this invention are: This invention achieves reliable end sealing of the plunger under high pressure and high temperature conditions through a water jacket structure and a multi-stage sealing structure, allowing it to withstand high pressure and alternating loads during operation. A threaded sleeve is threadedly installed in the first-stage hole as the end seal of the sealing structure. The water jacket, the three-stage sealing structure, and the guide sleeve are installed in the second-stage hole, with the plunger and the third-stage hole having a clearance fit. An annular cooling channel is formed between the water jacket, the plunger, and the sealing sleeve, providing flow space for the cooling medium. This annular cooling channel is connected to the cooling medium inlet and outlet on the sealing sleeve. Microstructures are provided on the sidewall of the plunger. These microstructures interact with the cooling medium during operation, reducing the medium velocity gradient near the wall surface, thereby reducing the adhesion between the wall surface and the cooling medium. The frictional resistance is reduced, thereby decreasing heat generation and wear fatigue between the plunger and the sealing structure. While the plunger generates frictional heat during operation, the circulating cooling medium continuously removes heat through the water jacket channel, ensuring that the entire sealing area is at a suitable operating temperature and preventing materials such as polyurethane from hardening, losing elasticity, or failing due to high temperatures. Each UN sealing ring corresponds to a support ring, stacked to form a three-stage sealing structure. The annular groove on the UN sealing ring interlocks with the annular protrusion on the support ring. While supporting adjacent UN sealing rings, the support ring expands the sides of the annular groove of the UN sealing ring through the annular protrusion, so that the UN sealing ring is pressed tightly against the plunger and the sealing sleeve to form a seal, providing the sealing function of the entire sealing structure under extreme operating conditions.

[0017] This invention sets the included angle between the cooling medium inlet connector and the cooling medium outlet connector to less than or equal to 60°, allowing the cooling medium inlet connector and the cooling medium outlet connector to be installed in nearly the same direction as the cooling medium delivery pipeline. This increases the contact area between the cooling medium and the plunger, improves cooling efficiency, avoids the operation of installing the cooling medium inlet connector and the cooling medium outlet connector from two directions as required by the traditional arrangement, and reduces the requirements for actual installation space.

[0018] This invention incorporates a pressure detection device on the quick-connect fitting at the cooling medium outlet. This enables real-time leakage monitoring, failure detection, and leakage management, preventing the danger of sudden high-pressure working medium ejection. When a small amount of normal leakage or initial failure occurs in the seal, a pressure change is generated in the pipeline connected to the quick-connect fitting. By installing a pressure detection device on the pipeline at the cooling system outlet, operators can monitor this pressure change in real time, immediately recognizing potential main seal failure. This provides real-time, online, and non-invasive monitoring of the seal status, offering valuable early warning time for planned maintenance before a leak escalates into a serious incident.

[0019] This invention also incorporates miniature pressure and temperature sensors to promptly reflect pressure fluctuations and temperature changes when seals experience wear, leakage, or abnormal operating conditions, enabling real-time monitoring and early warning of equipment operation and improving the reliability and maintenance efficiency of the sealing system. By incorporating a buffer structure within the balanced pressure relief channel, and connecting both ends of the balanced pressure relief channel to the working chamber that drives the push rod and the annular cooling channel, a limited pressure release and pressure equalization channel is provided when system pressure increases instantaneously, allowing for appropriate adjustment of the pressure difference across the three-stage sealing structure. Furthermore, the balanced pressure relief channel also provides a certain fluid buffering effect during the reciprocating motion of the plunger, resulting in smoother system pressure changes and significantly improving the stability and reliability of the device. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 This is a schematic diagram of the end-sealing cooling structure for the plunger according to the present invention; Figure 2 This is a schematic diagram of the sealing structure and the plunger assembly end face of the present invention; Figure 3 This is a partially enlarged view of the multi-stage sealing structure of the present invention; Figure 4 This is a partially enlarged view of the cooling water jacket structure of the present invention; Figure 5 This is a schematic diagram of the cooling medium flow path of the present invention; Figure 6 For the present invention Figure 1 A magnified view of a portion of point A in the middle.

[0022] In the diagram: 1. Piston; 2. Threaded sleeve; 3. Water jacket; 4. Support ring; 5. Guide sleeve; 6. Sealing sleeve; 7. First O-ring seal; 8. Second O-ring seal; 9. UN seal; 10. Quick-connect coupling; 11. Combination gasket; 12. Third O-ring seal; 13. U-ring seal. Detailed Implementation

[0023] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. Example 1 This embodiment provides an end-sealing cooling structure for a plunger, such as... Figures 1-6 As shown, it includes: a sealing sleeve 6 and a plunger 1 penetrating the core of the sealing sleeve 6; a threaded sleeve 2, a water jacket 3, a three-stage sealing structure, and a guide sleeve 5 are sequentially arranged between the plunger 1 and the sealing sleeve 6. Through the water jacket 3 structure and the multi-stage sealing structure, reliable sealing of the plunger 1 end under high pressure and high temperature conditions can be achieved, and it can withstand high pressure and alternating loads during operation; the sealing sleeve 6 is provided with three-stage stepped holes, namely a first-stage hole, a second-stage hole, and a third-stage hole with successively decreasing diameters; the threaded sleeve 2 is threadedly installed in the first-stage hole, serving as the end seal of the sealing structure. The water jacket 3, the three-stage sealing structure, and the guide sleeve 5 are installed in the second-stage hole, and the plunger 1 is clearance-fitted with the third-stage hole. The water jacket 3 forms an annular cooling channel with the plunger 1 and the sealing sleeve 6 respectively, providing flow space for the cooling medium. The annular cooling channel is connected to the cooling medium inlet and cooling medium outlet on the sealing sleeve 6. While the plunger 1 generates frictional heat during operation, the circulating cooling medium continuously carries away heat through the water jacket 3 channel, ensuring that the entire sealing area is at a suitable working temperature and preventing materials such as polyurethane from hardening, losing elasticity, or failing due to high temperature. The three-stage sealing structure includes three UN sealing rings 9 and three support rings 4, with the UN sealing rings 9 and support rings 4 arranged at intervals. The support rings 4 serve as support structural components for the single-stage seal, preventing gap failure of adjacent UN sealing rings 9 under ultra-high system pressure. Each UN sealing ring 9 corresponds to one support ring 4, stacked to form a three-stage sealing structure. The UN sealing rings 9 are provided with annular grooves, with the openings of the annular grooves facing the guide sleeve 5 (i.e., the high-pressure side). The support rings 4 are provided with annular protrusions, which are inserted into the annular grooves. While supporting adjacent UN sealing rings 9, the support rings 4 also spread open the annular grooves of the UN sealing rings 9 through the annular protrusions, so that the UN sealing rings 9 are pressed tightly against the plunger 1 and the sealing sleeve 6 respectively to form a seal, providing a sealing function for the entire sealing structure under extreme operating conditions.

[0025] The plunger 1 has microstructures on its sidewall. These microstructures have a triangular cross-section with dimensions on the order of micrometers, specifically a=20μm, b=30μm, and c=50μm. During operation, these microstructures interact with the cooling medium. Based on fluid dynamics principles, they reduce the velocity gradient of the medium near the wall, thereby reducing the viscous resistance between the wall and the cooling medium, ultimately lowering frictional resistance. The microstructures on the plunger surface reduce the resistance between the sealing structure and the plunger, thus reducing heat generation and wear fatigue between them, improving the performance of the sealing structure without compromising the sealing effect.

[0026] A mounting cavity is provided at the axial center of the plunger 1. A miniature sensor structure, including a miniature pressure sensor and a temperature sensor, is installed within this cavity. These sensors are positioned near the sealing area to monitor pressure changes and operating temperature within the sealing cavity in real time. The signals from the miniature pressure and temperature sensors are output to an external monitoring system via a wireless module. By using these miniature pressure and temperature sensors, pressure fluctuations and temperature changes can be promptly reflected when the seal experiences wear, leakage, or abnormal operating conditions, enabling real-time monitoring and early warning of equipment operation status, thereby improving the reliability and maintenance efficiency of the sealing system.

[0027] The plunger 1 has a balanced pressure relief channel inside, which contains a buffer structure. The balanced pressure relief channel is axially aligned with the plunger and its two ends are connected to the working chamber that pushes the push rod and the annular cooling channel. When the system pressure rises instantaneously, it provides a limited pressure release and pressure equalization channel, allowing for appropriate adjustment of the pressure difference across the three-stage sealing structure. This effectively reduces the instantaneous pressure gradient at the sealing interface, decreases the contact stress and impact load on the seal, thereby delaying seal wear and increasing seal life. Simultaneously, the balanced channel also provides a certain fluid buffering effect during the plunger's reciprocating motion, making system pressure changes more stable and significantly improving the stability and reliability of the device.

[0028] UN sealing ring 9, as a component of a single-stage sealing structure, is suitable for high-temperature and high-pressure conditions. It features corrosion resistance and long service life, improving the reliability of the sealing system. The material chosen is polyurethane, which possesses excellent mechanical strength and extrusion resistance, serving as the primary seal. The guide sleeve 5 provides precise radial support for the high-speed reciprocating plunger 1, transitionally pressing it into the second-stage hole of the sealing sleeve 6. This restricts the lateral displacement and vibration of the plunger 1, while also bearing the lateral force of the plunger 1, preventing direct wear between the plunger 1 and the water jacket 3 and the three-stage sealing structure. The inner hole of the guide sleeve 5 fits tightly with the plunger 1, and its outer diameter fits tightly with the sealing sleeve 6, ensuring coaxiality. The inner surface of the guide sleeve 5 has extremely low roughness to reduce friction with the plunger 1. The guide sleeve 5 is made of 45 carbon structural steel, which, through tempering heat treatment, achieves excellent comprehensive mechanical properties and withstands mechanical wear. During installation, a special press is used to smoothly and vertically press the guide sleeve 5 into the sealing sleeve 6 until its end face fits tightly against the shoulder of the stepped hole. The inner hole of the guide sleeve 5 directly guides the plunger 1, and its coaxiality directly determines the service life of the entire sealing assembly. After pressing, the guide sleeve 5 must be securely fixed without any loosening.

[0029] As a further implementation, the annular groove is disposed on one side of the UN sealing ring 9, and the annular protrusion is disposed on one side of the support ring 4. The cross-sectional shapes of the annular groove and the annular protrusion are wedge-shaped and trapezoidal, respectively, and the cross-sectional size of the annular groove is larger than that of the annular protrusion. Thus, the annular protrusion opens up both sides of the annular groove of the UN sealing ring 9, so that the UN sealing ring 9 is pressed tightly against the plunger 1 and the sealing sleeve 6 to form a seal.

[0030] As a further implementation, the pipe joints are a cooling medium inlet joint and a cooling medium outlet joint; the included angle between the axes of the cooling medium inlet joint and the cooling medium outlet joint is less than or equal to 60°; by setting the included angle between the axes of the cooling medium inlet joint and the cooling medium outlet joint to less than or equal to 60°, the cooling medium inlet joint and the cooling medium outlet joint can be installed in nearly the same direction as the cooling medium delivery pipeline, avoiding the operation of installing the cooling medium inlet joint and the cooling medium outlet joint from two directions as in the traditional layout, and reducing the requirements for actual installation space size.

[0031] As a further implementation, a first O-ring 7 and a second O-ring 8 are provided on the end face of one end of the third-level hole of the sealing sleeve 6, wherein the curvature of the first O-ring 7 is greater than the curvature of the second O-ring 8.

[0032] As a further implementation, a U-shaped sealing ring 13 is provided on the side of the water jacket 3 near the plunger 1, with the notch of the U-shaped sealing ring 13 facing the cooling flow channel. The U-shaped sealing ring 13 is a key component for dynamic sealing between the plunger 1 and the sealing structure. When the pressure of the liquid medium acts on the U-shaped groove, it forces the U-shaped sealing ring 13 to press tightly against the water jacket 3 outwards and against the plunger 1 inwards, achieving a pressure self-tightening seal. The higher the pressure, the greater the sealing force. The U-shaped sealing ring 13 is made of cast polyurethane, which has extremely high mechanical strength, wear resistance, and extrusion resistance. As a further implementation, a third O-ring 12 is provided on the side of the water jacket 3 near the sealing sleeve 6. The water jacket 3 is press-fitted with the sealing sleeve 6 through the sealing ring. Both the U-shaped sealing ring 13 and the third O-ring 12 are arranged at the end of the water jacket 3 near the threaded sleeve 2. The O-ring is used to achieve a static seal between the sealing sleeve 6 and the water jacket 3, preventing the cooling and lubricating medium from leaking from the gap, and at the same time providing initial pre-tightening force for the U-shaped sealing ring 13. The O-ring is made of rubber, which has good wear resistance and elasticity. It is installed in a rectangular groove designed on the water jacket 3, and the initial sealing force is generated by the pre-compression during installation.

[0033] As a further implementation, the sealing sleeve 6 is made of carbon structural steel and undergoes quenching and tempering heat treatment to obtain sufficient strength and toughness to withstand system pressure and assembly stress.

[0034] As a further implementation, quick-connect couplings 10 are installed at both the cooling medium inlet and outlet, and a combination washer 11 is installed on the quick-connect coupling 10. During installation, the combination washer 11 is first fitted onto the thread root of the quick-connect coupling 10, and then screwed into the threaded hole of the sealing sleeve 6 and tightened. The combination washer 11 undergoes plastic deformation at this point, ensuring an absolute seal between the quick-connect coupling 10 and the sealing sleeve 6, preventing cooling medium leakage. The cooling medium flows in from one quick-connect coupling 10 and enters the annular flow channel formed by the inner wall of the sealing sleeve 6 and the outer wall of the plunger 1. The annular flow channel directly surrounds the area subjected to the highest frictional heat and medium heat. After absorbing heat here, the cooling medium flows out from the other quick-connect coupling 10 above, completing an active cooling cycle, enabling the sealing structure to operate reliably at high temperatures.

[0035] As a further implementation, a pressure detection device is installed on the quick-connect coupling 10 at the cooling medium outlet. When a small amount of normal leakage or initial failure occurs in the seal, the working medium will first accumulate here, causing a pressure change in the pipeline connected to the quick-connect coupling 10, realizing real-time leakage monitoring, failure monitoring, and leakage management functions, and avoiding the danger of sudden injection of high-pressure working medium. Under normal circumstances, the cooling chamber is filled with cooling medium and maintains a certain circulating pressure. However, once the sealing structure experiences a slight failure or the permissible small leakage increases, the high-pressure working medium will break through its seal and seep into the cooling chamber, leading to contamination of the cooling medium and an abnormal increase in the pressure of the cooling circuit. By installing a pressure detection device on the pipeline at the cooling system outlet, operators can monitor this pressure change in real time, thereby immediately knowing that the main seal may have failed, realizing real-time, online, and non-invasive monitoring of the sealing status. This provides valuable early warning time, allowing for planned maintenance before the leak escalates into a serious accident.

[0036] As a further implementation, the support ring 4 is made of an engineering plastic with self-lubricating properties, and its hardness is higher than that of the UN sealing ring 9, so that the UN sealing ring 9 can effectively fill the radial gap between the plunger 1 and the sealing sleeve 6. Although the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. An end-sealing cooling structure for a plunger, characterized in that, include: A sealing sleeve and a plunger penetrating the core of the sealing sleeve are provided. Microstructures are provided on the sidewall of the plunger. A threaded sleeve, a water jacket, a three-stage sealing structure, and a guide sleeve are sequentially arranged between the plunger and the sealing sleeve. The sealing sleeve has three stages of stepped holes, namely, a first-stage hole, a second-stage hole, and a third-stage hole with successively decreasing diameters. The threaded sleeve is threaded into the first-stage hole, and the water jacket, the three-stage sealing structure, and the guide sleeve are installed in the second-stage hole. The plunger and the third-stage hole are clearance-fitted. An annular cooling channel is formed between the water jacket, the plunger, and the sealing sleeve, and this annular cooling channel communicates with the cooling medium inlet and outlet on the sealing sleeve. A pressure detection device is provided on the quick-connect fitting at the cooling medium outlet. The three-stage sealing structure includes three UN sealing rings and three support rings, with the UN sealing rings and support rings arranged at intervals, and each UN sealing ring corresponding to one support ring; the UN sealing ring is provided with an annular groove, and the support ring is provided with an annular protrusion, the annular protrusion is inserted into the annular groove, and expands the UN sealing ring, so that the UN sealing ring is pressed tightly with the plunger and the sealing sleeve to form a seal.

2. The end-sealing cooling structure for a plunger as described in claim 1, characterized in that, The annular groove is disposed on one side of the UN sealing ring, and the annular protrusion is disposed on one side of the support ring. The cross-sectional shapes of the annular groove and the annular protrusion are wedge-shaped and trapezoidal, respectively, and the cross-sectional dimension of the annular groove is larger than that of the annular protrusion.

3. The end-sealing cooling structure for a plunger as described in claim 2, characterized in that, The pipe joints are a cooling medium inlet joint and a cooling medium outlet joint; the included angle between the axes of the cooling medium inlet joint and the cooling medium outlet joint is less than or equal to 60°.

4. The end-sealing cooling structure for a plunger as described in claim 1, characterized in that, The sealing sleeve has a first O-ring and a second O-ring on one end face of the third hole, and the curvature of the first O-ring is greater than that of the second O-ring.

5. The end-sealing cooling structure for a plunger as described in claim 4, characterized in that, A U-shaped sealing ring is provided on the side of the water jacket near the plunger, with the notch of the U-shaped sealing ring facing the cooling channel.

6. The end-sealing cooling structure for a plunger as described in claim 5, characterized in that, A third O-ring is provided on the side of the water jacket near the sealing sleeve. Both the U-ring and the third O-ring are arranged at the end of the water jacket near the threaded sleeve.

7. The end-sealing cooling structure for a plunger as described in claim 1, characterized in that, The sealing sleeve is made of carbon structural steel and has undergone quenching and tempering heat treatment.

8. The end-sealing cooling structure for a plunger as described in claim 1, characterized in that, Quick-connect couplings are installed at both the cooling medium inlet and the cooling medium outlet, and combination washers are installed on the quick-connect couplings.

9. The end-sealing cooling structure for a plunger as described in claim 1, characterized in that, The pressure detection device is a pressure sensor.

10. The end-sealing cooling structure for a plunger as claimed in claim 1, characterized in that, The support ring is made of engineering plastic with self-lubricating properties, and its hardness is higher than that of the UN sealing ring, which allows the UN sealing ring to effectively fill the radial gap between the plunger and the sealing sleeve.

Images