Long-life high-pressure nitrogen balance cylinder

Abstract

The application relates to the technical field of balance cylinders, in particular to a long-life high-pressure nitrogen balance cylinder, which comprises a cylinder body, a piston rod movably arranged on the cylinder body, a bottom cover, a middle sleeve and a snap spring piece; a cylindrical gas storage part is arranged on the side of the cylinder body and is in communication with the cylinder body; the bottom cover is arranged on one end of the cylinder body; the end of the cylinder body far from the bottom cover is an inlet end; an annular step is arranged on the inlet end of the cylinder body; the end of the middle sleeve far from the bottom cover is in abutting contact with the annular step; an arc-shaped snap spring groove is arranged on the inner wall of the cylinder body; an inclined guide surface is arranged on the side of the middle sleeve close to the rod body; the arc-shaped snap spring groove and the inclined guide surface are arranged in axial alignment; when the middle sleeve is inwardly arranged in the cylinder body, the inclined guide surface is used for guiding the middle sleeve to slide into the inner wall of the cylinder body; when the middle sleeve abuts against the annular step, the arc-shaped snap spring groove is opposite to the inclined guide surface on the inner side of the middle sleeve; and the snap spring piece is arranged in the arc-shaped snap spring groove and is used for pressing the inclined guide surface of the middle sleeve.

Description

Technical Field

[0001] This invention relates to the field of balance cylinder technology, and in particular discloses a long-life high-pressure nitrogen balance cylinder. Background Technology

[0002] Nitrogen balance cylinders are widely used in machine tools, automated equipment, and other fields as elastic counterweights and constant force support components. Their operational stability and service life directly affect the processing accuracy and maintenance cycle of the equipment. Existing nitrogen balance cylinders generally suffer from limited gas storage chamber volume and large gas pressure fluctuations during piston reciprocating motion, which can easily lead to unstable output force and aggravated erosion by high-pressure airflow. At the same time, the dustproof sealing structure at the piston rod dynamic seal is of a single type, which is difficult to adapt to high-frequency reciprocating conditions for a long time. External dust, chips, and other impurities can easily enter the cylinder body, causing wear on the sliding pairs and seals. In addition, the guide limit component assembly has insufficient reliability and is prone to movement and loosening under high-pressure conditions. The gas pressure control interface layout is simple, and the pressure adjustment operation after installation is inconvenient. It is difficult to meet the requirements of long service life and high reliability under long-term high-pressure and high-frequency operation. Summary of the Invention

[0003] In order to overcome the shortcomings and deficiencies of the existing technology, the purpose of this invention is to provide a long-life high-pressure nitrogen balance cylinder.

[0004] To achieve the above objectives, the present invention provides a long-life high-pressure nitrogen balance cylinder, comprising a cylinder body, a piston rod movably mounted on the cylinder body, a bottom cover, a middle sleeve, and a retaining spring; a cylindrical gas storage section communicating with the cylinder body is provided on the side of the cylinder body, the cylindrical gas storage section forming a closed gas chamber interconnected with the inner cavity of the cylinder body; the bottom cover is fitted onto one end of the cylinder body, the end of the cylinder body away from the bottom cover is the inlet end, the inlet end of the cylinder body is provided with an annular step, and the end of the middle sleeve away from the bottom cover abuts against and limits the movement of the annular step; an arc-shaped retaining spring groove is provided on the inner side wall of the cylinder body, the middle sleeve... The sleeve has an inclined guide surface on the side near the rod body. The arc-shaped snap ring groove is axially aligned with the inclined guide surface. When the middle sleeve is installed from the cylinder body, the inclined guide surface is used to guide it to slide into the inner wall of the cylinder body. After the middle sleeve is pressed against the annular step, the arc-shaped snap ring groove is aligned with the inclined guide surface on the inner side of the middle sleeve. The snap ring is locked in the arc-shaped snap ring groove and presses against the inclined guide surface of the middle sleeve. The annular step and the snap ring cooperate to form a bidirectional axial limit for the middle sleeve. The middle sleeve has a through hole for the piston rod to pass through. The piston rod is movably installed in the cylinder body through the through hole.

[0005] First, pre-compress the retaining ring and fit it onto the end of the middle sleeve with the inclined guide surface. Then, push the middle sleeve and retaining ring together from the cylinder inlet end inwards, guiding them into the inner wall of the cylinder with the help of the inclined guide surface. Continue sliding until the end of the middle sleeve away from the bottom cover abuts against the annular step at the cylinder inlet end. At this point, the retaining ring is axially aligned with the arc-shaped retaining ring groove on the inner side wall of the cylinder. The retaining ring automatically opens and embeds into the arc-shaped retaining ring groove, pressing against the inclined guide surface of the middle sleeve. The annular step and the retaining ring cooperate to form a bidirectional axial limit for the middle sleeve. A cylindrical air storage section is connected to the side of the cylinder, sharing the same internal cavity as the cylinder. Together, they form a sealed air chamber, increasing the air storage volume to smooth out air pressure fluctuations caused by the reciprocating motion of the piston rod and stabilize the output thrust. This pre-installed structure eliminates the need to insert tooling operating springs deep into the cylinder, making assembly convenient. The inclined guide surface facilitates the smooth installation of the intermediate sleeve and spring into the cylinder, and also forms a reliable surface contact limit with the spring to resist axial forces under high pressure, prevent the intermediate sleeve from shifting, protect the sealing structures between the intermediate sleeve and the cylinder and piston rod, reduce the risk of air leakage, and effectively improve the operational stability and service life of the balance cylinder under high pressure and high frequency conditions.

[0006] The piston rod includes a rod body and a piston head disposed at one end of the rod body. The outer diameter of the piston head is larger than the outer diameter of the rod body. The rod body is slidably disposed in a through hole, and the piston head is slidably disposed in the inner cavity of the cylinder. An axially penetrating vent hole is provided on the piston head, which connects the cavities on both sides of the piston head. The vent hole is used to eliminate the back pressure resistance generated by the reciprocating extension and retraction of the piston rod.

[0007] The piston head has multiple sets of air passages, which are evenly spaced along the circumference of the piston head. The air passages are either stepped or straight through holes.

[0008] The piston rod consists of a rod body and a large-diameter piston head. After assembly, the rod body slides through the through hole of the middle sleeve, and the piston head slides in the inner cavity of the cylinder. The piston head has multiple sets of axially penetrating vent holes evenly spaced along the circumference. The vent holes can adopt a stepped through-hole or straight through-hole structure. During the high-speed reciprocating extension and retraction of the piston rod, the cavities on both sides of the piston head achieve rapid gas convection through the multiple sets of vent holes, effectively eliminating the back pressure resistance generated by the piston movement, avoiding problems such as negative pressure blockage, movement jamming, and impact vibration caused by the piston compressing gas. This makes the piston rod's forward and backward movement smoother and more stable. At the same time, the evenly distributed porous structure can balance the airflow and disperse the pressure, significantly reducing the erosion and turbulence loss of high-pressure airflow, improving the response consistency and operational stability of the reciprocating motion of the balance cylinder, and further extending the service life of the entire machine.

[0009] The stepped through hole includes a first diameter section and a second diameter section connected to the first diameter section. The first diameter section is close to the free end face of the piston head, and the second diameter section is close to the middle sleeve. The inner diameter of the first diameter section is larger than the inner diameter of the second diameter section.

[0010] The vent holes on the piston head adopt a stepped through-hole structure with large inlets and small outlets. This includes a large inner diameter first vent section near the free end of the piston head and a small inner diameter second vent section near the middle sleeve side. The two vent sections are smoothly connected. When the piston rod reciprocates, the high-pressure gas first enters rapidly through the large-diameter first vent section and then exits at a constant speed through the small-diameter second vent section. Combined with the combined effect of multiple circumferentially distributed vent holes, the gas in the cavities on both sides of the piston head can be quickly circulated, completely eliminating the back pressure resistance and negative pressure stagnation generated by the piston's reciprocating motion. The stepped vent structure forms a progressive airflow throttling and buffering effect, effectively balancing the changes in cylinder pressure, reducing airflow turbulence and pressure impact, making the piston rod extension and retraction movements smoother and more stable, and significantly improving the operational stability and response consistency of the balance cylinder under high-pressure conditions.

[0011] The inner sidewall of the cylinder is also provided with a wear-resistant sleeve, which is fixedly installed on the inner sidewall of the cylinder, and the outer wall of the piston head slides against the inner sidewall of the wear-resistant sleeve.

[0012] A wear-resistant sleeve is fixedly fitted to the inner wall of the cylinder. The outer wall of the piston head slides against the inner wall of the wear-resistant sleeve throughout the entire process. The independently set wear-resistant sleeve completely isolates the piston head from the metal inner wall of the cylinder, avoiding direct hard friction contact between the piston head and the cylinder during the reciprocating sliding process. Compared with the structure where the cylinder body directly rubs against the cylinder, this structure can effectively protect the inner wall of the cylinder from wear and scoring, and prevent problems such as air leakage, pressure loss, and operation jamming caused by cylinder wear and deformation. At the same time, the wear-resistant sleeve has excellent sliding wear resistance and dimensional stability, which can accurately guide and straighten the piston head, effectively limit the radial runout of the piston rod, reduce sliding friction resistance, reduce wear loss of piston reciprocating motion, and greatly improve the stability and motion accuracy of the balance cylinder in high-frequency reciprocating operation. There is no need to replace the entire cylinder; only the wear-resistant sleeve needs to be replaced to complete the maintenance, which greatly reduces the later maintenance cost of the equipment and effectively extends the overall service life of the balance cylinder.

[0013] The outer wall of the middle sleeve near the cylinder body is provided with a first annular groove and a second annular groove, which are distributed along the length of the middle sleeve. The balance cylinder also includes a first O-ring and a second O-ring. The first O-ring is embedded in the first annular groove, and the second O-ring is embedded in the second annular groove. Both the first O-ring and the second O-ring are clamped and sealed between the middle sleeve and the inner wall of the cylinder body to achieve a double-layer radial seal and prevent high-pressure nitrogen from leaking from the sealed gas chamber.

[0014] The outer wall of the middle sleeve is axially spaced with a first annular groove and a second annular groove. The first O-ring and the second O-ring are respectively embedded in the two annular grooves, forming two independent radial sealing structures between the middle sleeve and the inner wall of the cylinder. After assembly, the two O-rings are pressed together in the fitting gap between the middle sleeve and the cylinder, forming a double-layer barrier seal for the high-pressure nitrogen in the cylinder. Compared with a single-layer sealing structure, it can effectively distribute the high-pressure gas load, make up for the defects of single-seal rings that are prone to loosening, aging and leakage under long-term high-pressure compression, significantly improve the pressure holding performance of the sealed gas chamber, effectively prevent high-pressure nitrogen from slowly leaking from the assembly gap between the cylinder and the middle sleeve, ensure the long-term stable working pressure of the balance cylinder, reduce the pressure decay rate, reduce the number of frequent gas replenishment maintenance, and significantly improve the sealing reliability of the balance cylinder under high-pressure conditions and the service life of the whole machine.

[0015] The middle sleeve has a third annular groove, a fourth annular groove, and an annular oil groove on the side near the piston rod. The third annular groove, the fourth annular groove, and the annular oil groove are distributed along the length of the middle sleeve, and the annular oil groove is located between the third annular groove and the fourth annular groove. The balance cylinder also includes a third O-ring and a Y-shaped sealing ring. The third O-ring is embedded in the third annular groove, and the Y-shaped sealing ring is embedded in the fourth annular groove. The lip of the Y-shaped sealing ring is set towards the sealed air chamber. The third O-ring and the Y-shaped sealing ring are both pressed tightly between the middle sleeve and the outer wall of the piston rod to form a multi-seal structure. The annular oil groove can store lubricating grease to continuously lubricate the reciprocating sliding of the piston rod.

[0016] The middle sleeve has a third annular groove, a fourth annular groove, and an annular oil groove on the side near the piston rod. The third annular groove, the fourth annular groove, and the annular oil groove are distributed along the length of the middle sleeve, and the annular oil groove is located between the third annular groove and the fourth annular groove. The balance cylinder also includes a third O-ring and a Y-shaped sealing ring. The third O-ring is embedded in the third annular groove, and the Y-shaped sealing ring is embedded in the fourth annular groove. The lip of the Y-shaped sealing ring is set towards the sealed air chamber. The third O-ring and the Y-shaped sealing ring are both pressed tightly between the middle sleeve and the outer wall of the piston rod to form a multi-seal structure. The annular oil groove can store lubricating grease to continuously lubricate the reciprocating sliding of the piston rod.

[0017] The annular oil groove is sandwiched between the third O-ring and the Y-ring seal, allowing grease to simultaneously wet the piston rod friction surfaces on both sides, lubricating both front and rear seals. If the oil groove were located on the outside of the seal, the grease would easily be carried out of the cylinder by the piston rod, failing to continuously supply the two seals. The Y-ring seal faces the high-pressure nitrogen in the sealed gas chamber, and the high-pressure gas can easily permeate outward in small amounts along the piston rod surface. The middle oil groove forms a buffer chamber, retaining the permeated gas and reducing the pressure load on the outer third O-ring, thus alleviating the pressure burden on the outer seal.

[0018] The cylindrical gas storage section is integrally formed with the cylinder body, and the internal cavity of the cylindrical gas storage section is connected to the internal cavity of the cylinder body, effectively expanding the overall gas storage volume of the sealed gas chamber. An inflation and pressure relief valve assembly is installed at the end of the cylindrical gas storage section, and the inflation and pressure relief valve assembly is connected to the internal cavity of the cylindrical gas storage section. The inflation and pressure relief valve assembly includes an inflation valve core, a pressure relief regulating valve core, and a pressure detection connector. The inflation valve core is used to fill the sealed gas chamber with high-pressure nitrogen, and the pressure relief regulating valve core is used to fine-tune the release of high-pressure gas in the chamber and regulate the working pressure of the chamber. The pressure detection connector is connected to an external pressure detection instrument, which can collect the gas pressure value inside the sealed gas chamber in real time through the pressure detection connector, realizing real-time monitoring of the internal pressure.

[0019] The cylindrical gas storage section and cylinder body adopt an integrated molding structure, which has high overall strength, good structural stability and no assembly gaps. The internal cavity of the cylindrical gas storage section is directly connected to the internal cavity of the cylinder body, effectively expanding the overall gas storage volume of the sealed gas chamber. This can significantly buffer the sudden rise and fall of gas pressure in the chamber during the reciprocating motion of the piston rod, reduce pressure fluctuations and make the output support force of the balance cylinder more uniform and stable. The end of the cylindrical gas storage section is equipped with an integrated inflation and pressure relief valve assembly. High-pressure nitrogen can be injected into the sealed gas chamber through the inflation valve core. The pressure relief regulating valve core can precisely adjust the release of high-pressure gas in the chamber to regulate the working pressure. At the same time, the pressure detection connector can be connected to an external detection instrument to collect the gas pressure data in the chamber in real time, realizing real-time monitoring and dynamic control of the high-pressure chamber pressure. The structure has a high degree of integration, accurate pressure regulation and convenient detection, effectively improving the pressure stability and equipment maintainability of the balance cylinder under high-pressure working conditions, and adapting to the needs of high-precision and long-cycle high-pressure operations.

[0020] The balance cylinder also includes an inner dustproof component and an outer dustproof component. The inner side wall of the middle sleeve is provided with a dustproof groove. The inner dustproof component is housed in the dustproof groove and abuts against the outer wall of the piston rod. It is used to prevent external dust and debris from entering the cylinder body through the sliding gap of the piston rod. The outer dustproof component is located on the side of the retaining spring near the inlet end. The outer dustproof component is axially clamped between the outer end face of the middle sleeve and the end face of the annular step of the cylinder body. It is used to seal the assembly gap between the middle sleeve and the cylinder body and prevent impurities from entering the sealed air chamber from the mating gap.

[0021] This balance cylinder features a double-layer dustproof structure consisting of an inner dustproof component and an outer dustproof component. A dustproof groove is formed on the inner wall of the middle sleeve for the inner dustproof component to be embedded and fixed. The inner wall of the inner dustproof component tightly abuts against the outer wall of the piston rod, effectively preventing external dust, iron filings, and coolant impurities from entering the cylinder body through the reciprocating sliding gap of the piston rod. This avoids impurities scratching the piston rod mirror surface, wearing the seals, and contaminating the internal air chamber. The outer dustproof component is axially clamped and fixed between the outer end face of the middle sleeve and the annular step end face of the cylinder body, on the outer side of the retaining spring. This completely seals the assembly gap between the middle sleeve and the cylinder body, preventing external impurities from seeping into the sealed air chamber from the cylinder body assembly gaps. Through this double dustproof protection, the intrusion path of impurities is blocked in all directions, significantly reducing the wear and failure probability of the cylinder's sealing and sliding structures. This effectively improves the working environment of the balance cylinder under high-frequency and harsh operating conditions, significantly enhancing the overall operational stability and long-term service life of the machine.

[0022] The inner dustproof component includes a first main body, a second main body that is telescopically disposed within the first main body, and a third main body that is telescopically disposed within the second main body. The first main body, the second main body, and the third main body are all provided with coaxial through holes at their centers, and the piston rod is sequentially inserted into the interior of each hole. The first main body is fixedly housed in the dustproof groove, and the second and third main bodies can slide relative to each other along the axial direction of the piston rod. The inner wall of the hole of the third main body is in contact with the outer wall of the piston rod.

[0023] The first main body has a first limiting flange at the end of its inner hole, and the second main body has a second limiting boss on its outer wall that aligns with the first limiting flange. The second main body has a second limiting flange at the end of its inner hole, and the third main body has a third limiting boss on its outer wall that aligns with the second limiting flange. Each limiting flange and the limiting boss abut axially to limit the extension and retraction stroke of the corresponding main body and prevent the telescopic nested structure from axially dislodging.

[0024] The first, second, and third main bodies are all made of modified polyurethane material, and the three are set with gradient hardness. The hardness of the first main body is Shore A90-95, and it is rigidly embedded and positioned in the dustproof groove with high hardness. The hardness of the second main body is Shore A80-85, which takes into account both axial expansion elasticity and sliding wear resistance. The hardness of the third main body is Shore A70-75, which fits tightly against the outer wall of the piston rod in a low elasticity interference state. The gradient hardness setting can adapt to the radial runout and axial movement of the piston rod, automatically compensate for the wear of the lip, maintain effective dustproof fit for a long time, and significantly improve the service life and protective reliability of the dustproof structure.

[0025] The inner dustproof component adopts a three-section nested telescopic structure, consisting of a first main body, a second main body, and a third main body nested sequentially. Each main body has a coaxial through hole in its center for the piston rod to pass through and assemble. The first main body is fixedly embedded in the dustproof groove of the middle sleeve, while the second and third main bodies can slide relative to each other along the axial direction of the piston rod. The inner wall of the third main body always fits against the outer wall of the piston rod to achieve dustproof contact and sealing. By setting a first limiting flange and a second limiting flange on the first and second main bodies respectively, and setting a second limiting boss and a third limiting boss at corresponding mating positions, the axial abutment of the flanges and bosses precisely limits the telescopic stroke of each main body, effectively preventing the nested structure from loosening or falling out, and ensuring the telescopic dustproof structure. The assembly stability and structural integrity are ensured. All three main body sections are made of modified polyurethane material with a gradient hardness design. The first main body section, with a high hardness of Shore A90-95, ensures overall rigid positioning without loosening. The second main body section, with a medium hardness of Shore A80-85, balances smooth sliding and structural support. The third main body section, with a low hardness of Shore A70-75, fits the piston rod in a flexible interference fit, adapting to radial runout and axial movement during piston rod operation. It automatically compensates for minor lip wear, maintaining a tight, dustproof fit for extended periods. This avoids problems such as rigid contact wear, poor sealing, dust ingress, and air leakage, greatly improving the environmental adaptability, wear resistance, and long-term protective reliability of the dustproof structure, further extending the overall service life of the balance cylinder.

[0026] The inner wall of the first aperture section is provided with an annular flow guide chamfer. The annular flow guide chamfer is located at the junction of the first aperture section and the second aperture section. The annular flow guide chamfer has a rounded transition structure, which can eliminate the dead angle of airflow when the high-pressure airflow passes through the stepped through hole, reduce airflow turbulence and cavitation, further buffer the impact of high-pressure airflow, and improve the stability of piston operation.

[0027] An annular chamfered guide with a rounded transition is provided at the junction of the first and second diameter sections of the stepped through-hole. This makes the diameter change position smooth and without right-angle steps. When the high-pressure airflow passes through the stepped through-hole, it can smoothly change direction and be split along the annular chamfered guide. This effectively eliminates the airflow dead angles and vortex stagnation areas that are easy to generate in traditional right-angle step structures. It greatly reduces the turbulence and high-speed erosion of the high-pressure airflow, weakens the pressure impact caused by sudden changes in airflow, and makes the gas convection on both sides of the piston more uniform, smooth and stable. This further improves the smoothness of the piston rod's reciprocating extension and retraction process, reduces vibration, abnormal noise and pressure fluctuations, and improves the output accuracy and working stability of the balance cylinder under high-pressure conditions.

[0028] The external dustproof component is a static sealing dustproof gasket with a metal skeleton. It has an embedded annular rigid skeleton and is covered with a high-pressure resistant rubber layer. The annular rigid skeleton is used to ensure the axial compressive strength of the external dustproof component. The upper and lower surfaces of the high-pressure resistant rubber layer are tightly pressed against the outer end face of the middle sleeve and the end face of the annular step, respectively, which can maintain the sealing and dustproof effect of the assembly gap for a long time and avoid deformation failure under the impact of high-pressure airflow.

[0029] A buffer pad is fixedly embedded on the end face of the bottom cover facing the inner cavity of the cylinder. The buffer pad is set directly opposite the return limit position of the piston head. When the piston rod is fully retracted, the end face of the piston head flexibly contacts the buffer pad to absorb the impact energy of the piston return, avoid abnormal noise and structural wear caused by hard metal collision, realize return buffering and noise reduction, and extend the service life of the piston and the bottom cover.

[0030] The retaining ring is an open-type elastic retaining ring with a circular cross-section. The inner ring sidewall of the retaining ring and the inclined guide surface of the middle sleeve are linearly and arc-shaped and pressed together. The circular cross-section can adapt to the slight axial movement and tilt of the middle sleeve under high pressure conditions, and always maintain a uniform pressing and limiting force to avoid stress concentration that could lead to retaining ring breakage or middle sleeve loosening.

[0031] The bottom cover is equipped with a valve core and a detachable plug on the valve core. The plug covers the exposed outside of the valve core, which can form a secondary sealing protection for the valve core. At the same time, it prevents external dust and moisture from entering the valve core, avoids valve core corrosion and jamming failure, and ensures the sealing reliability of the valve core under long-term high-pressure conditions.

[0032] The valve core can be used as an auxiliary inflation port to fill the cavity with high-pressure nitrogen, or the gas in the cavity can be quickly released by pressing the valve core. It can be used to quickly release air pressure during equipment maintenance. Together with the inflation and depressurization valve assembly at the end of the cylindrical gas storage section, it forms a dual-end air pressure regulation structure to adapt to the inflation, depressurization and maintenance operation needs in different installation scenarios.

[0033] The retaining ring of this balance cylinder adopts an open-type elastic retaining ring with a circular cross-section. The inner arc surface of the retaining ring and the inclined guide surface of the middle sleeve form a precise arc-shaped linear fitting and clamping structure. Compared with the traditional right-angle cross-section retaining ring, the circular cross-section can adapt to the slight axial movement and angular tilt of the middle sleeve under high pressure conditions. It can automatically adapt the fitting angle, evenly distribute the clamping stress, and maintain a stable and balanced axial limiting clamping force throughout the process. This effectively avoids problems such as retaining ring fatigue fracture, deformation and loosening, and middle sleeve displacement and loosening caused by local stress concentration, ensuring the long-term stability and reliability of the two-way limiting structure of the middle sleeve; at the same time, the bottom cover integrates Equipped with a valve core and a removable protective plug, the valve core serves as an auxiliary pressure charging and depressurization interface. Working in conjunction with the valve assembly in the cylindrical gas storage section, it enables dual-end pressure regulation, adapting to maintenance, charging, and depressurization operations in various installation scenarios. The exposed valve core is completely covered and protected by the plug, forming a secondary sealing structure. This not only assists in sealing the pressure and improving the chamber's pressure-holding effect, but also effectively prevents external dust, moisture, and oil from entering the valve core, preventing corrosion, jamming, and sealing failure. This significantly improves the valve core's operational stability and service life under long-term high-pressure conditions, reducing equipment failure probability and maintenance costs.

[0034] In actual assembly and use, the dual-end air pressure regulation structure of this balance cylinder can be used to achieve precise adjustment and rapid maintenance of the nitrogen pressure inside the cavity: Under normal installation conditions, the inflation and depressurization valve assembly at the end of the cylindrical gas storage section is used first for precise pressure adjustment. The pressure detection connector is connected to an external pressure gauge to read the internal pressure of the sealed gas cavity in real time. When the pressure inside the cavity is too low, high-pressure nitrogen is injected into the cavity through the inflation valve core until the pressure reaches the set working pressure of the equipment. When the pressure inside the cavity is too high, the depressurization regulating valve core is slowly rotated to perform a small amount of pressure relief, achieving precise fine-tuning of the pressure and ensuring constant output pressure and stable support accuracy of the balance cylinder. When the installation space of the balance cylinder is limited, the valve body of the outer gas storage section is blocked by the frame, or the equipment needs to be shut down for maintenance and the internal pressure needs to be quickly emptied, the plug on the valve core of the bottom cover can be removed, and the valve core can be pressed directly to quickly release the high-pressure nitrogen inside the cavity, achieving instantaneous depressurization and rapid pressure relief for maintenance. After maintenance, nitrogen can be added again through the valve core and the plug can be reinstalled to form a secondary sealing protection for the valve core. With the precise fine-tuning of the main valve and the rapid pressure charging and depressurization of the bottom cover valve core, it can adapt to nitrogen pressure regulation operations with different installation conditions and different precision requirements. It is easy to operate, has a wide adjustment range, and high equipment maintenance efficiency, effectively ensuring the pressure stability and reliability of the balance cylinder under long-term high-pressure working conditions.

[0035] The piston rod is provided with a first connector at the end away from the cylinder body, and the cylinder body is provided with a second connector at the end away from the piston rod. The first connector and the second connector are respectively used to connect to an external load and a mounting base.

[0036] Both the first connector and the second connector are provided with fisheye hinge joints. One side of the second connector is provided with an adjustable thread structure connected to the piston rod. The center distance between the two fisheye hinge joints can be adjusted by screwing the threads. The distance between the center distance between the two fisheye hinge joints is greater than the center distance between the assembly holes at the two mounting points on the external frame.

[0037] When the piston rod is fully retracted to its internal mechanical dead point and the piston head end face is tightly fitted against the bottom surface of the middle sleeve, the center distance between the two fisheye hinge joints is the minimum hole center distance. When the balance cylinder is assembled onto the equipment frame, the center distance between the assembly holes at the two mounting points on the frame is less than this minimum hole center distance. The maximum retraction stroke of the piston rod is limited by the frame assembly dimensions, ensuring that there is always an axial clearance between the piston head end face and the bottom surface of the middle sleeve to prevent rigid impact between the two. When the piston rod retracts to near its end, the high-pressure nitrogen in the sealed gas chamber is depressurized through the throttling damping of the gas passage in the piston head. The gas buffering is completed by relying on the reserved clearance, reducing the impact wear caused by reciprocating motion and extending the service life of the balance cylinder.

[0038] In practice, when the balance cylinder retracts until the piston head presses against the bottom surface of the middle sleeve, the minimum center-to-center distance between the two fisheye hinge joints is set to 200mm. When assembled on the machine tool tilting frame, the center-to-center distance of the frame assembly holes is set to 194mm, which is less than the minimum center-to-center distance, and the two form a 6mm axial buffer gap. The piston rod retraction stroke is limited by the frame size, and the piston head never contacts the bottom surface of the middle sleeve. At the end of the retraction, high-pressure nitrogen gas is throttled, buffered, and absorbs shock through the gas passage hole of the piston head.

[0039] The beneficial effects of this invention are as follows: By integrally setting a cylindrical air storage section on the side of the cylinder body, the volume of the sealed air chamber is increased, effectively buffering air pressure fluctuations and stabilizing the output pressure. Combined with a pre-assembled snap ring and inclined guide surface, a bidirectional axial limiting structure is formed, simplifying the assembly process and providing strong positioning rigidity. This effectively resists high-pressure impacts and vibrations, preventing loosening and movement of the intermediate sleeve. The piston head is equipped with multiple sets of stepped air passages and rounded flow guide chamfers, which can quickly conduct air pressure on both sides of the piston, eliminate back pressure resistance, reduce airflow turbulence and erosion, and significantly improve the smoothness of the piston rod's reciprocating motion. The wear-resistant sleeve built into the cylinder body achieves piston suspension and wear-resistant guidance, preventing cylinder body wear and scoring, and reducing maintenance costs. The inner and outer sides of the intermediate sleeve are respectively equipped with a multi-layer dynamic sealing structure consisting of double-layer radial seals and O-rings combined with Y-type seals. An annular oil reservoir is set between the two seals to achieve bidirectional continuous lubrication, buffer air pressure penetration, and trap wear debris, significantly improving the durability and leak-proof capability of the dynamic seal. This invention further employs an inner and outer double-layer dustproof structure, coupled with a three-section gradient hardness telescopic dustproof component, which can adapt to piston rod wobble and wear, maintaining a long-term close dustproof effect. At the same time, a circular cross-section retaining spring enhances the limiting stability, the bottom cover buffer pad eliminates return impact noise, and the bottom cover valve core and the end inflation and pressure relief valve assembly form a double-end inflation and pressure relief control structure, taking into account both precise pressure regulation and quick maintenance and pressure relief functions. Combined with the secondary protection structure of the plug, it effectively protects the valve core. The overall structure is optimized from multiple dimensions such as gas storage and pressure stabilization, guiding and limiting, sealing and lubrication, dust protection, pressure regulation, and impact and wear resistance, which greatly reduces the probability of leakage, jamming, wear, and failure under high-pressure conditions, and significantly improves the operating accuracy, stability and overall service life of the nitrogen balance cylinder. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a cross-sectional view of the entire invention; Figure 3 For the present invention Figure 2 A magnified structural diagram of part A in the middle; Figure 4 This is a cross-sectional view of the first embodiment of the piston head of the present invention; Figure 5 This is a cross-sectional view of a second embodiment of the piston head of the present invention; Figure 6 This is a schematic diagram of the internal dustproof component and piston rod of the present invention.

[0041] The reference numerals in the figures include: 1. Cylinder block; 2. Piston rod; 3. Bottom cover; 4. Intermediate sleeve; 5. Snap ring; 6. Cylindrical air reservoir; 7. Arc-shaped snap ring groove; 8. Inclined guide surface; 9. Through hole; 11. Rod body; 12. Piston head; 13. Air passage; 14. Stepped through hole; 15. Straight through hole; 16. First diameter section; 17. Second diameter section; 18. Wear-resistant sleeve; 19. First annular groove; 21. Second annular groove; 22. First O-ring; 23. Second O-ring; 24. Third annular groove; 25. 26. Fourth annular groove; 27. Annular oil groove; 28. Third O-ring; 29. ​​Y-type sealing ring; 30. Inflation and pressure relief valve assembly; 31. Inner dustproof component; 32. Outer dustproof component; 33. Dustproof groove; 34. First main body; 35. Second main body; 36. Third main body; 37. Hole body; 38. Annular guide chamfer; 39. Valve core; 41. Plug; 42. First connecting piece; 43. Second connecting piece; 44. Fisheye hinge joint; 45. Hole center distance; 46. Adjustable thread structure. Detailed Implementation

[0042] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention.

[0043] Please see Figures 1 to 6 As shown, a long-life high-pressure nitrogen balance cylinder of the present invention includes a cylinder body 1, a piston rod 2 movably mounted on the cylinder body 1, a bottom cover 3, a middle sleeve 4, and a retaining spring 5; a cylindrical gas storage part 6 communicating with the cylinder body 1 is provided on the side of the cylinder body 1, and the cylindrical gas storage part 6 and the inner cavity of the cylinder body 1 form an interconnected sealed gas chamber; the bottom cover 3 is closed on one end of the cylinder body 1, and the end of the cylinder body 1 away from the bottom cover 3 is the inlet end, and the inlet end of the cylinder body 1 is provided with an annular step, and the end of the middle sleeve 4 away from the bottom cover 3 abuts against and limits the movement of the annular step; an arc-shaped retaining spring groove 7 is provided on the inner wall of the cylinder body 1, and the middle sleeve 4 is close to the piston rod. An inclined guide surface 8 is provided on one side of the body. The arc-shaped snap ring groove 7 is axially aligned with the inclined guide surface 8. When the middle sleeve 4 is inserted into the cylinder body 1, the inclined guide surface 8 is used to guide it to slide into the inner wall of the cylinder body 1. After the middle sleeve 4 is pressed against the annular step, the arc-shaped snap ring groove 7 is directly aligned with the inclined guide surface 8 on the inner side of the middle sleeve 4. The snap ring 5 is locked in the arc-shaped snap ring groove 7 and presses against the inclined guide surface 8 of the middle sleeve 4. The annular step and the snap ring 5 cooperate to form a bidirectional axial limit for the middle sleeve 4. The middle sleeve 4 is provided with a through hole 9 for the piston rod 2 to pass through. The piston rod 2 is movably installed in the cylinder body 1 through the through hole 9.

[0044] First, the snap ring 5 is pre-compressed and fitted onto the end of the middle sleeve 4 with the inclined guide surface 8. Then, the middle sleeve 4, together with the snap ring 5, is pushed inward from the inlet end of the cylinder body 1. Guided by the inclined guide surface 8, it slides into the inner wall of the cylinder body 1 and continues to slide until the end of the middle sleeve 4 away from the bottom cover 3 abuts against the annular step at the inlet end of the cylinder body 1. At this time, the snap ring 5 is axially aligned with the arc-shaped snap ring groove 7 on the inner side wall of the cylinder body 1. The snap ring 5 automatically opens and embeds into the arc-shaped snap ring groove 7 and presses against the inclined guide surface 8 of the middle sleeve 4. The annular step and the snap ring 5 cooperate to form a bidirectional axial limit for the middle sleeve 4. A cylindrical air storage section 6 is connected to the side of the cylinder body 1. Together with the inner cavity of cylinder 1, it forms a sealed air chamber, increasing the air storage volume to smooth the air pressure fluctuations generated by the reciprocating motion of piston rod 2 and stabilize the output thrust. This pre-installed structure eliminates the need to insert tooling operating springs deep into cylinder 1, making assembly convenient. The inclined guide surface 8 facilitates the smooth installation of the middle sleeve 4 along with the spring into cylinder 1, and also forms a reliable surface contact limit with the spring to resist axial forces under high pressure, prevent the middle sleeve 4 from shifting, protect the sealing structures between the middle sleeve 4 and cylinder 1 and piston rod 2, reduce the risk of air leakage, and effectively improve the operational stability and service life of the balance cylinder under high pressure and high frequency conditions.

[0045] The piston rod 2 includes a rod body 11 and a piston head 12 disposed at one end of the rod body 11. The outer diameter of the piston head 12 is larger than the outer diameter of the rod body 11. The rod body 11 is slidably disposed in the through hole 9, and the piston head 12 is slidably disposed in the inner cavity of the cylinder body 1. An axially penetrating vent hole 13 is provided on the piston head 12. The vent hole 13 connects the cavities on both sides of the piston head 12. The vent hole 13 is used to eliminate the back pressure resistance generated by the reciprocating extension and retraction of the piston rod 2.

[0046] The vent 13 is provided in multiple sets, and the multiple sets of vent 13 are evenly spaced along the circumference of the piston head 12; the vent 13 is a stepped through hole 14 or a straight through hole 15.

[0047] The piston rod 2 consists of a rod body 11 and a large-diameter piston head 12. After assembly, the rod body 11 slides through the through hole 9 of the middle sleeve 4, and the piston head 12 slides in the inner cavity of the cylinder body 1. Multiple sets of axially penetrating air holes 13 are evenly spaced along the circumference of the piston head 12. The air holes 13 can adopt a stepped through hole 14 or a straight through hole 15 structure. During the high-speed reciprocating extension and retraction of the piston rod 2, the cavities on both sides of the piston head 12 achieve rapid gas convection through the multiple sets of air holes 13, effectively eliminating the back pressure resistance generated by the piston movement, avoiding problems such as negative pressure blockage, movement jamming, and impact vibration caused by the piston compressing gas, making the forward and backward movement of the piston rod 2 smoother and more stable. At the same time, the evenly distributed porous structure can balance the airflow and disperse the pressure, greatly reducing the erosion and turbulence loss of high-pressure airflow, improving the response consistency and operation stability of the reciprocating motion of the balance cylinder, and further extending the service life of the whole machine.

[0048] In the first embodiment, the vent 13 is a straight through hole 15. This straight through hole 15 is opened along the axial direction of the cylinder body 1 to achieve pressure balance for gas flow within the cavity.

[0049] In the second embodiment, the air passage 13 is a stepped through hole 14, which includes a first diameter section 16 and a second diameter section 17 connected to the first diameter section 16. The first diameter section 16 is close to the free end face of the piston head 12, and the second diameter section 17 is close to the middle sleeve 4. The inner diameter of the first diameter section 16 is larger than the inner diameter of the second diameter section 17.

[0050] The vent 13 on the piston head 12 adopts a stepped through-hole 14 structure with a large inlet and a small outlet, including a large inner diameter first orifice section 16 near the free end of the piston head 12 and a small inner diameter second orifice section 17 near the side of the middle sleeve 4. The two orifice sections are smoothly connected. When the piston rod 2 reciprocates, the high-pressure gas first enters rapidly through the large diameter first orifice section 16, and then exits at a constant speed through the small diameter second orifice section 17. With the combined action of multiple circumferentially distributed vent 13, the gas in the cavities on both sides of the piston head 12 can be quickly connected, completely eliminating the back pressure resistance and negative pressure stagnation phenomenon generated by the reciprocating motion of the piston. The stepped orifice structure forms a progressive airflow throttling and buffering effect, effectively balancing the changes in cylinder pressure, weakening airflow turbulence and pressure impact, making the extension and retraction of the piston rod 2 smoother and more stable, and greatly improving the operational stability and response consistency of the balance cylinder under high pressure conditions.

[0051] The inner wall of the cylinder body 1 is also provided with a wear-resistant sleeve 18, which is fixedly installed on the inner wall of the cylinder body 1, and the outer wall of the piston head 12 slides against the inner wall of the wear-resistant sleeve 18.

[0052] A wear-resistant sleeve 18 is fixedly fitted to the inner wall of the cylinder body 1. The outer wall of the piston head 12 slides against the inner wall of the wear-resistant sleeve 18 throughout the entire process. The independently set wear-resistant sleeve 18 completely isolates the piston head 12 from the metal inner wall of the cylinder body 1, avoiding direct hard friction contact between the piston head 12 and the cylinder body 1 during the reciprocating sliding process. Compared with the structure where the cylinder body 1 directly rubs against the cylinder body, this structure can effectively protect the inner wall of the cylinder body 1 from wear and scoring, and prevent problems such as air leakage, pressure loss, and operation jamming caused by wear and deformation of the cylinder body 1. At the same time, the wear-resistant sleeve 18 has excellent sliding wear resistance and dimensional stability, and can play a precise guiding and straightening role for the piston head 12, effectively limiting the radial runout of the piston rod 2, reducing sliding friction resistance, reducing wear loss of piston reciprocating motion, and greatly improving the stability and motion accuracy of the high-frequency reciprocating operation of the balance cylinder. There is no need to replace the entire cylinder body 1, only the wear-resistant sleeve 18 needs to be replaced to complete the maintenance, which greatly reduces the later maintenance cost of the equipment and effectively extends the overall service life of the balance cylinder.

[0053] The outer wall of the middle sleeve 4 near the cylinder body 1 is provided with a first annular groove 19 and a second annular groove 21. The first annular groove 19 and the second annular groove 21 are distributed along the length direction of the middle sleeve 4. The balance cylinder also includes a first O-ring 22 and a second O-ring 23. The first O-ring 22 is embedded in the first annular groove 19, and the second O-ring 23 is embedded in the second annular groove 21. The first O-ring 22 and the second O-ring 23 are both clamped and sealed between the middle sleeve 4 and the inner wall of the cylinder body 1 to achieve a double-layer radial seal and prevent high-pressure nitrogen leakage in the sealed air chamber.

[0054] The outer wall of the middle sleeve 4 is axially spaced with a first annular groove 19 and a second annular groove 21. The first O-ring 22 and the second O-ring 23 are respectively embedded in the two annular grooves, forming two independent radial sealing structures between the middle sleeve 4 and the inner wall of the cylinder body 1. After assembly, the two O-rings are pressed between the middle sleeve 4 and the cylinder body 1, forming a double-layer barrier seal for the high-pressure nitrogen in the cylinder. Compared with a single-layer sealing structure, it can effectively distribute the high-pressure gas load, make up for the defects of single-seal rings that are prone to loosening, aging and leakage due to long-term high-pressure compression, greatly improve the pressure holding performance of the sealed gas chamber, effectively prevent high-pressure nitrogen from slowly leaking from the assembly gap between the cylinder body 1 and the middle sleeve 4, ensure the long-term stable working pressure of the balance cylinder, reduce the pressure decay rate, reduce the number of frequent gas replenishment maintenance, and significantly improve the sealing reliability and service life of the balance cylinder under high-pressure conditions.

[0055] The middle sleeve 4 has a third annular groove 24, a fourth annular groove 25, and an annular oil groove 26 on the side near the piston rod 2. The third annular groove 24, the fourth annular groove 25, and the annular oil groove 26 are distributed along the length of the middle sleeve 4, and the annular oil groove 26 is located between the third annular groove 24 and the fourth annular groove 25. The balance cylinder also includes a third O-ring 27 and a Y-shaped sealing ring 28. The third O-ring 27 is embedded in the third annular groove 24, and the Y-shaped sealing ring 28 is embedded in the fourth annular groove 25. The lip of the Y-shaped sealing ring 28 is set towards the sealed air chamber. The third O-ring 27 and the Y-shaped sealing ring 28 are both pressed tightly between the middle sleeve 4 and the outer wall of the piston rod 2 to form a multi-seal structure. The annular oil groove 26 can store lubricating grease to continuously lubricate the reciprocating sliding of the piston rod 2.

[0056] The middle sleeve 4 has a third annular groove 24, a fourth annular groove 25, and an annular oil groove 26 on the side near the piston rod 2. The third annular groove 24, the fourth annular groove 25, and the annular oil groove 26 are distributed along the length of the middle sleeve 4, and the annular oil groove 26 is located between the third annular groove 24 and the fourth annular groove 25. The balance cylinder also includes a third O-ring 27 and a Y-shaped sealing ring 28. The third O-ring 27 is embedded in the third annular groove 24, and the Y-shaped sealing ring 28 is embedded in the fourth annular groove 25. The lip of the Y-shaped sealing ring 28 is set towards the sealed air chamber. The third O-ring 27 and the Y-shaped sealing ring 28 are both pressed tightly between the middle sleeve 4 and the outer wall of the piston rod 2 to form a multi-seal structure. The annular oil groove 26 can store lubricating grease to continuously lubricate the reciprocating sliding of the piston rod 2.

[0057] The annular oil groove 26 is sandwiched between the third O-ring and the Y-shaped seal, allowing grease to simultaneously wet the friction surfaces of the piston rod 2 on both sides, thus lubricating both front and rear seals. If the oil groove were located on the outside of the seal, the grease would easily be carried out of the cylinder 1 by the piston rod 2, making it impossible to continuously supply the two seals. The Y-shaped seal faces the high-pressure nitrogen in the sealed gas chamber, and the high-pressure gas can easily permeate outward in small amounts along the surface of the piston rod 2. The middle oil groove forms a buffer chamber, retaining the permeated small amount of gas, reducing the gas pressure load acting on the outer third O-ring, and alleviating the pressure burden on the outer seal.

[0058] The cylindrical gas storage section 6 is integrally formed with the cylinder body 1. The internal cavity of the cylindrical gas storage section 6 is connected to the internal cavity of the cylinder body 1, effectively expanding the overall gas storage volume of the sealed gas chamber. An inflation and pressure relief valve assembly 29 is installed at the end of the cylindrical gas storage section 6. The inflation and pressure relief valve assembly 29 is connected to the internal cavity of the cylindrical gas storage section 6. The inflation and pressure relief valve assembly 29 includes an inflation valve core, a pressure relief regulating valve core, and a pressure detection connector. The inflation valve core is used to fill the sealed gas chamber with high-pressure nitrogen. The pressure relief regulating valve core is used to fine-tune the release of high-pressure gas in the chamber and regulate the working pressure of the chamber. The pressure detection connector is connected to an external pressure detection instrument. Through the pressure detection connector, the external detection instrument can collect the gas pressure value inside the sealed gas chamber in real time, realizing real-time monitoring of the internal pressure.

[0059] The cylindrical gas storage section 6 and the cylinder body 1 adopt an integral molding structure, which has high overall strength, good structural stability and no assembly gaps. The internal cavity of the cylindrical gas storage section 6 is directly connected to the internal cavity of the cylinder body 1, which effectively expands the overall gas storage volume of the sealed gas chamber. This can significantly buffer the sudden rise and fall of gas pressure in the chamber during the reciprocating motion of the piston rod 2, reduce pressure fluctuations and make the output support force of the balance cylinder more uniform and stable. The end of the cylindrical gas storage section 6 is equipped with an integrated inflation and pressure relief valve assembly 29. High-pressure nitrogen can be injected into the sealed gas chamber through the inflation valve core. The pressure relief regulating valve core can precisely adjust the release of high-pressure gas in the chamber to regulate the working pressure. At the same time, the pressure detection connector can be connected to an external detection instrument to collect the gas pressure data in the chamber in real time, realizing real-time monitoring and dynamic control of the high-pressure chamber pressure. The structure has high integration, accurate pressure regulation and convenient detection, which effectively improves the pressure stability and equipment maintainability of the balance cylinder under high-pressure working conditions and is suitable for high-precision and long-cycle high-pressure operation requirements.

[0060] The balance cylinder also includes an inner dustproof component 31 and an outer dustproof component 32. The inner side wall of the middle sleeve 4 is provided with a dustproof groove 33. The inner dustproof component 31 is housed in the dustproof groove 33 and abuts against the outer wall of the piston rod 2 to prevent external dust and debris from entering the cylinder body 1 along the sliding gap of the piston rod 2. The outer dustproof component 32 is located on the side of the retaining spring 5 near the inlet end. The outer dustproof component 32 is axially clamped between the outer end face of the middle sleeve 4 and the annular step end face of the cylinder body 1 to seal the assembly gap between the middle sleeve 4 and the cylinder body 1 and prevent impurities from entering the sealed air chamber from the mating gap.

[0061] This balance cylinder is equipped with a double-layer dustproof structure consisting of an inner dustproof component 31 and an outer dustproof component 32. A dustproof groove 33 is opened on the inner side wall of the middle sleeve 4 for the inner dustproof component 31 to be embedded and fixed. The inner wall of the inner dustproof component 31 tightly abuts against the outer wall of the piston rod 2, which can effectively prevent external dust, iron filings, coolant impurities from entering the cylinder body 1 through the reciprocating sliding gap of the piston rod 2, avoiding impurities from scratching the mirror surface of the piston rod 2, wearing the seals, and contaminating the inner cavity air chamber. The outer dustproof component 32 is axially clamped and fixed between the outer end face of the middle sleeve 4 and the annular step end face of the cylinder body 1, at the outer position of the retaining spring 5, which can completely seal the assembly gap between the middle sleeve 4 and the cylinder body 1, preventing external impurities from seeping into the sealed air chamber from the assembly gap of the cylinder body 1. Through double dustproof protection, the intrusion path of impurities is blocked in all directions, which greatly reduces the wear and failure probability of the cylinder's sealing structure and sliding structure, effectively improves the working environment of the balance cylinder under high-frequency harsh conditions, and significantly improves the overall operating stability and long service life of the machine.

[0062] The inner dustproof component 31 includes a first main body 34, a second main body 35 telescopically disposed within the first main body 34, and a third main body 36 telescopically disposed within the second main body 35; the first main body 34, the second main body 35, and the third main body 36 are all provided with coaxial through holes 37 at their centers, and the piston rod 2 is sequentially inserted into the interior of each hole 37; the first main body 34 is fixedly housed in the dustproof groove 33, and the second main body 35 and the third main body 36 can telescopically slide relative to each other along the axial direction of the piston rod 2, and the inner wall of the hole 37 of the third main body 36 is in contact with the outer wall of the piston rod 2.

[0063] The first main body 34 has a first limiting flange at the end of its inner hole, and the second main body 35 has a second limiting boss on its outer wall that aligns with the first limiting flange. The second main body 35 has a second limiting flange at the end of its inner hole, and the third main body 36 has a third limiting boss on its outer wall that aligns with the second limiting flange. Each limiting flange and the limiting boss abuts axially to limit the extension and retraction stroke of the corresponding main body and prevent the telescopic nested structure from axially dislodging.

[0064] The first main body 34, the second main body 35, and the third main body 36 are all made of modified polyurethane material, and the three are set with gradient hardness. The first main body 34 has a Shore A hardness of 90-95 and is rigidly embedded and positioned in the dustproof groove 33 with high hardness. The second main body 35 has a Shore A hardness of 80-85, which takes into account both axial expansion elasticity and sliding wear resistance. The third main body 36 has a Shore A hardness of 70-75 and fits tightly against the outer wall of the piston rod 2 with low elasticity interference. The gradient hardness setting can adapt to the radial runout and axial movement of the piston rod 2, automatically compensate for the wear of the lip, maintain effective dustproof fit for a long time, and significantly improve the service life and protective reliability of the dustproof structure.

[0065] The inner dustproof component 31 adopts a three-section nested telescopic structure, consisting of a first main body 34, a second main body 35, and a third main body 36 nested sequentially. Each main body has a coaxial through hole 37 at its center for the piston rod 2 to pass through and be assembled. The first main body 34 is fixedly embedded in the dustproof groove 33 of the middle sleeve 4. The second main body 35 and the third main body 36 can slide relative to each other along the axial direction of the piston rod 2. The inner wall of the third main body 36 always fits against the outer wall of the piston rod 2 to achieve dustproof contact sealing. By setting a first limiting flange and a second limiting flange on the first main body 34 and the second main body 35 respectively, and setting a second limiting boss and a third limiting boss at corresponding mating positions, the axial abutment of the flanges and bosses precisely limits the telescopic stroke of each main body, effectively preventing the nested structure from loosening or detaching. To ensure the assembly stability and structural integrity of the telescopic dustproof structure, the three main body sections are all made of modified polyurethane material with a gradient hardness design. The first main body section 34, with a high hardness of Shore A90-95, ensures overall rigid positioning without loosening. The second main body section 35, with a medium hardness of Shore A80-85, balances smooth sliding and structural support. The third main body section 36, with a low hardness of Shore A70-75, fits the piston rod 2 in a flexible interference fit, which can adapt to the radial runout and axial movement of the piston rod 2 during operation. It can automatically compensate for minor wear on the lip and maintain a tight fit for a long time, avoiding problems such as rigid contact wear, poor sealing, dust ingress, and air leakage. This greatly improves the environmental adaptability, wear resistance, and long-term protective reliability of the dustproof structure, and further extends the overall service life of the balance cylinder.

[0066] The inner wall of the first aperture section 16 is provided with an annular guide chamfer 38. The annular guide chamfer 38 is located at the junction of the first aperture section 16 and the second aperture section 17. The annular guide chamfer 38 has a rounded transition structure, which can eliminate the dead angle of airflow when the high-pressure airflow passes through the stepped through hole 14, reduce airflow turbulence and cavitation, further buffer the impact of high-pressure airflow, and improve the stability of piston operation.

[0067] An annular guide chamfer 38 with a rounded transition is provided at the junction of the first diameter section 16 and the second diameter section 17 of the stepped through-hole 14, so that the change position of the diameter is smooth and without right-angle steps. When the high-pressure airflow passes through the stepped through-hole 14, it can smoothly change direction and be split along the annular guide chamfer 38, effectively eliminating the airflow dead angle and vortex stagnation area that are easy to be generated by the traditional right-angle step structure, greatly reducing the turbulence disturbance and high-speed erosion of the high-pressure airflow, weakening the pressure impact caused by the sudden change of airflow, making the gas convection on both sides of the piston more uniform, smooth and stable, further improving the motion stability of the piston rod 2 during the reciprocating extension and retraction process, reducing vibration, abnormal noise and pressure fluctuation, and improving the output accuracy and working stability of the balance cylinder under high pressure conditions.

[0068] The outer dustproof component 32 is a static sealing dustproof gasket with a metal skeleton. It has an embedded annular rigid skeleton and is covered with a high-pressure resistant rubber layer. The annular rigid skeleton is used to ensure the axial compressive strength of the outer dustproof component 32. The upper and lower surfaces of the high-pressure resistant rubber layer are tightly pressed against the outer end face of the middle sleeve 4 and the end face of the annular step, respectively. This can maintain the sealing and dustproof effect of the assembly gap for a long time and avoid deformation failure under the impact of high-pressure airflow.

[0069] A buffer pad is fixedly embedded on the end face of the bottom cover 3 facing the inner cavity of the cylinder 1. The buffer pad is set directly opposite the return limit position of the piston head 12. When the piston rod 2 is fully retracted, the end face of the piston head 12 flexibly contacts the buffer pad to absorb the impact energy of the piston return, avoid abnormal noise and structural wear caused by hard metal collision, realize return buffering and noise reduction, and extend the service life of the piston and the bottom cover 3.

[0070] The retaining ring 5 is an open-type elastic retaining ring with a circular cross-section. The inner ring sidewall of the retaining ring 5 is linearly and arc-shapedly pressed against the inclined guide surface 8 of the middle sleeve 4. The circular cross-section can adapt to the slight axial movement and tilt of the middle sleeve 4 under high pressure conditions, and always maintain a uniform pressing and limiting force to avoid stress concentration that could lead to retaining ring breakage or loosening of the middle sleeve 4.

[0071] The bottom cover 3 is provided with a valve core 39 and a plug 41 that is detachably installed on the valve core 39. The plug 41 covers the exposed valve core of the valve core 39, which can form a secondary sealing protection for the valve core 39, while preventing external dust and moisture from entering the valve core, avoiding valve core corrosion and jamming failure, and ensuring the sealing reliability of the valve core 39 under long-term high-pressure conditions.

[0072] The valve core 39 can be used as an auxiliary inflation port to fill the cavity with high-pressure nitrogen, or the gas in the cavity can be quickly released by pressing the valve core. It can be used to quickly release air pressure during equipment maintenance. Together with the inflation and depressurization valve assembly 29 at the end of the cylindrical gas storage section 6, it forms a dual-end air pressure regulation structure to adapt to the inflation, depressurization and maintenance operation needs under different installation scenarios.

[0073] The retaining ring 5 of this balance cylinder adopts an open-type elastic retaining ring with a circular cross-section. The inner arc surface of the retaining ring 5 and the inclined guide surface 8 of the middle sleeve 4 form a precise arc-shaped linear fitting and pressing structure. Compared with the traditional right-angle cross-section retaining ring, the circular cross-section can adapt to the slight axial movement and angular tilt generated by the middle sleeve 4 under high pressure conditions. It can automatically adapt the fitting angle, evenly distribute the pressing stress, and maintain a stable and balanced axial limiting pressing force throughout the process. This effectively avoids problems such as retaining ring fatigue fracture, deformation and loosening, and displacement and loosening of the middle sleeve 4 caused by local stress concentration, ensuring the long-term stability and reliability of the two-way limiting structure of the middle sleeve 4. At the same time, the bottom cover 3 integrates... It has a valve core 39 and a removable protective plug 41. The valve core 39 can be used as an auxiliary pressure charging and depressurization interface. It works with the valve group of the cylindrical air storage section 6 to achieve dual-end air pressure regulation, which is suitable for maintenance, charging and depressurization operations in different installation scenarios. The exposed valve core 39 is completely covered and protected by the plug 41 to form a secondary sealing protection structure. It can not only help to seal the air pressure and improve the pressure holding effect of the cavity, but also effectively prevent external dust, water vapor and oil from entering the valve core. It can prevent the valve core from rusting, jamming and sealing failure, which greatly improves the working stability and service life of the valve core 39 under long-term high pressure conditions, and reduces the probability of equipment failure and maintenance costs.

[0074] In actual assembly and use, the dual-end air pressure regulation structure of this balance cylinder can be used to achieve precise adjustment and rapid maintenance of the nitrogen pressure inside the cavity: Under normal installation conditions, the inflation and depressurization valve assembly 29 at the end of the cylindrical gas storage section 6 is used first for precise pressure adjustment. The pressure detection connector is connected to an external pressure gauge to read the internal pressure of the sealed gas cavity in real time. When the pressure inside the cavity is too low, high-pressure nitrogen is injected into the cavity through the inflation valve core until the pressure reaches the set working pressure of the equipment. When the pressure inside the cavity is too high, the depressurization regulating valve core is slowly rotated to perform a small amount of depressurization, so as to achieve precise fine adjustment of the pressure and ensure that the output pressure of the balance cylinder is constant and the support accuracy is stable. When the installation space of the balance cylinder is limited, the valve body of the outer gas storage section is obstructed by the frame, or the equipment needs to be shut down for maintenance and the pressure in the cavity needs to be quickly released, the plug 41 on the valve core 39 of the bottom cover can be removed, and the valve core 39 can be pressed directly to quickly release the high-pressure nitrogen in the cavity, achieving instantaneous pressure relief and rapid pressure reduction for maintenance. After maintenance, nitrogen can be added back through the valve core 39 and the plug 41 can be reinstalled to form a secondary sealing protection for the valve core 39. Through the precise fine-tuning of the main valve and the rapid pressure charging and depressurization of the valve core 39 of the bottom cover, it can adapt to nitrogen pressure adjustment operations with different installation conditions and different precision requirements. It is easy to operate, has a wide adjustment range, and high equipment maintenance efficiency, effectively ensuring the pressure stability and reliability of the balance cylinder under long-term high-pressure working conditions.

[0075] The piston rod 2 is provided with a first connector at the end away from the cylinder 1, and the cylinder 1 is provided with a second connector at the end away from the piston rod 2. The first connector and the second connector are respectively used to connect to the external load and the mounting base.

[0076] Both the first connector 42 and the second connector are provided with fisheye hinge joints 44. The second connector 43 is provided with an adjustable thread structure on one side and connected to the piston rod 2. The center distance 45 between the two fisheye hinge joints 44 can be adjusted by screwing the threads. The distance between the center distance 45 between the two fisheye hinge joints 44 is greater than the center distance 45 between the two mounting points on the external frame.

[0077] When the piston rod 2 is fully retracted to its internal mechanical dead point and the end face of the piston head 12 is tightly fitted against the bottom surface of the middle sleeve 4, the center distance between the two fisheye hinge joints 44 is the minimum hole center distance 45. When the balance cylinder is assembled onto the equipment frame, the center distance 45 between the assembly holes at the two mounting points on the frame is less than this minimum hole center distance 45. The maximum retraction stroke of the piston rod 2 is limited by the frame assembly dimensions, so that there is always an axial gap between the end face of the piston head 12 and the bottom surface of the middle sleeve 4, avoiding rigid impact between the two. When the piston rod 2 retracts to near the end, the high-pressure nitrogen in the sealed gas chamber is depressurized through the throttling damping of the gas passage 13 of the piston head 12. The gas buffering is completed by relying on the reserved gap, reducing the impact wear caused by reciprocating motion and extending the service life of the balance cylinder.

[0078] In practice, when the balance cylinder retracts to the point where the piston head 12 presses against the bottom surface of the middle sleeve 4, the minimum center-to-center distance 45 between the two fisheye hinge joints 44 is set to 200mm. When assembled on the machine tool tilting frame, the center-to-center distance 45 between the frame assembly holes is set to 194mm, which is less than the minimum center-to-center distance 45, forming a 6mm axial buffer gap. The retraction stroke of the piston rod 2 is limited by the frame size, and the piston head 12 never contacts the bottom surface of the middle sleeve 4. At the end of the retraction, high-pressure nitrogen gas is throttled, buffered, and absorbs shock through the air passage 13 of the piston head 12.

[0079] The rest of this embodiment is the same as that in Embodiment 1. Features not explained in this embodiment are explained using the methods in Embodiment 1, and will not be repeated here.

[0080] The above description is only a preferred embodiment of the present invention. For those skilled in the art, there will be changes in the specific implementation and application scope based on the ideas of the present invention. The content of this specification should not be construed as a limitation of the present invention.

Claims

1. A long-life high-pressure nitrogen balance cylinder, characterized in that: Includes a cylinder body (1), a piston rod (2) movably mounted on the cylinder body (1), a bottom cover (3), a middle sleeve (4), and a retaining ring (5); the cylinder body (1) has a cylindrical air storage part (6) connected to the cylinder body (1) on its side, and the cylindrical air storage part (6) and the inner cavity of the cylinder body (1) form a closed air chamber that communicates with each other; the bottom cover (3) is closed on one end of the cylinder body (1), and the end of the cylinder body (1) away from the bottom cover (3) is the inlet end, and the inlet end of the cylinder body (1) is provided with an annular step, and the end of the middle sleeve (4) away from the bottom cover (3) abuts against the annular step for limitation; the inner wall of the cylinder body (1) is provided with an arc-shaped retaining ring groove (7), and the side of the middle sleeve (4) near the rod is provided with an inclined guide surface (8). The arc-shaped retaining groove (7) and the inclined guide surface (8) are aligned axially. When the middle sleeve (4) is inserted into the cylinder (1), the inclined guide surface (8) is used to guide it to slide into the inner wall of the cylinder (1). After the middle sleeve (4) is pressed against the annular step, the arc-shaped retaining groove (7) is directly opposite the inclined guide surface (8) on the inner side of the middle sleeve (4). The retaining spring (5) is locked in the arc-shaped retaining groove (7) and presses against the inclined guide surface (8) of the middle sleeve (4). The annular step and the retaining spring (5) cooperate to form a bidirectional axial limit for the middle sleeve (4). The middle sleeve (4) is provided with a through hole (9) for the piston rod (2) to pass through. The piston rod (2) is movably set in the cylinder (1) through the through hole (9).

2. The long-life high-pressure nitrogen balance cylinder according to claim 1, characterized in that: The piston rod (2) includes a rod body (11) and a piston head (12) disposed at one end of the rod body (11). The outer diameter of the piston head (12) is larger than the outer diameter of the rod body (11). The rod body (11) is slidably disposed in the through hole (9). The piston head (12) is slidably disposed in the inner cavity of the cylinder (1). An axially penetrating vent hole (13) is provided on the piston head (12). The vent hole (13) connects the cavities on both sides of the piston head (12). The vent hole (13) is used to eliminate the back pressure resistance generated by the reciprocating extension and retraction of the piston rod (2).

3. A long-life high-pressure nitrogen balance cylinder according to claim 2, characterized in that: The air passage (13) is provided in multiple sets, and the multiple sets of air passage (13) are evenly spaced along the circumferential direction of the piston head (12); the air passage (13) is a stepped through hole (14) or a straight through hole (15).

4. A long-life high-pressure nitrogen balance cylinder according to claim 3, characterized in that: The stepped through hole (14) includes a first diameter section (16) and a second diameter section (17) connected to the first diameter section (16). The first diameter section (16) is close to the free end face of the piston head (12), and the second diameter section (17) is close to the middle sleeve (4). The inner diameter of the first diameter section (16) is larger than the inner diameter of the second diameter section (17).

5. A long-life high-pressure nitrogen balance cylinder according to claim 1, characterized in that: The inner wall of the cylinder (1) is also provided with a wear-resistant sleeve (18), which is fixedly installed on the inner wall of the cylinder (1), and the outer wall of the piston head (12) slides against the inner wall of the wear-resistant sleeve (18).

6. A long-life high-pressure nitrogen balance cylinder according to claim 1, characterized in that: The middle sleeve (4) is provided with a first annular groove (19) and a second annular groove (21) on the outer side wall near the cylinder body (1). The first annular groove (19) and the second annular groove (21) are distributed along the length direction of the middle sleeve (4). The balance cylinder also includes a first O-ring (22) and a second O-ring (23). The first O-ring (22) is embedded in the first annular groove (19), and the second O-ring (23) is embedded in the second annular groove (21). The first O-ring (22) and the second O-ring (23) are clamped and sealed between the middle sleeve (4) and the inner wall of the cylinder body (1) to achieve a double-layer radial seal and prevent high-pressure nitrogen leakage in the sealed air chamber.

7. A long-life high-pressure nitrogen balance cylinder according to claim 1, characterized in that: The middle sleeve (4) is provided with a third annular groove (24), a fourth annular groove (25) and an annular oil groove (26) on the side near the piston rod (2). The third annular groove (24), the fourth annular groove (25) and the annular oil groove (26) are distributed along the length direction of the middle sleeve (4). The annular oil groove (26) is located between the third annular groove (24) and the fourth annular groove (25). The balance cylinder also includes a third O-ring (27) and a Y-type sealing ring (28). The third O-ring (27) is embedded in the third annular groove (24), and the Y-type sealing ring (28) is embedded in the fourth annular groove (25). The lip of the Y-type sealing ring (28) is set towards the sealed air chamber. The third O-ring (27) and the Y-type sealing ring (28) are both pressed tightly between the middle sleeve (4) and the outer wall of the piston rod (2) to form a multi-seal structure. The annular oil groove (26) can store lubricating grease to continuously lubricate the reciprocating sliding of the piston rod (2).

8. A long-life high-pressure nitrogen balance cylinder according to claim 1, characterized in that: The cylindrical gas storage section (6) is integrally formed with the cylinder body (1). The internal cavity of the cylindrical gas storage section (6) is connected to the internal cavity of the cylinder body (1), effectively expanding the overall gas storage volume of the sealed gas chamber. The end of the cylindrical gas storage section (6) is equipped with a gas filling and pressure relief valve assembly (29). The gas filling and pressure relief valve assembly (29) is connected to the internal cavity of the cylindrical gas storage section (6). The gas filling and pressure relief valve assembly (29) includes a gas filling valve core, a pressure relief regulating valve core, and a pressure detection connector. The gas filling valve core is used to fill the sealed gas chamber with high-pressure nitrogen. The pressure relief regulating valve core is used to finely adjust the release of high-pressure gas in the chamber and adjust the working pressure of the chamber. The pressure detection connector is connected to an external pressure detection instrument. Through the pressure detection connector, the external detection instrument can collect the gas pressure value inside the sealed gas chamber in real time, realizing real-time monitoring of the internal pressure.

9. A long-life high-pressure nitrogen balance cylinder according to claim 1, characterized in that: The balance cylinder also includes an inner dustproof component (31) and an outer dustproof component (32). The inner wall of the middle sleeve (4) is provided with a dustproof groove (33). The inner dustproof component (31) is housed in the dustproof groove (33) and abuts against the outer wall of the piston rod (2) to prevent external dust and debris from entering the cylinder body (1) along the sliding gap of the piston rod (2). The outer dustproof component (32) is set on the side of the snap ring (5) near the inlet end. The outer dustproof component (32) is axially clamped between the outer end face of the middle sleeve (4) and the annular step end face of the cylinder body (1) to seal the assembly gap between the middle sleeve (4) and the cylinder body (1) and prevent impurities from entering the sealed air chamber from the mating gap.

10. A long-life high-pressure nitrogen balance cylinder according to claim 9, characterized in that: The inner dustproof component (31) includes a first main body (34), a second main body (35) telescopically disposed within the first main body (34), and a third main body (36) telescopically disposed within the second main body (35). The first main body (34), the second main body (35), and the third main body (36) are all provided with coaxial through holes (37) at their centers, and the piston rod (2) is sequentially inserted into each hole (37). The first main body (34) is fixedly housed in the dustproof groove (33), and the second main body (35) and the third main body (36) can slide relative to each other along the axial direction of the piston rod (2). The inner wall of the hole (37) of the third main body (36) is in contact with the outer wall of the piston rod (2).

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