In industrial production, many scenarios require high-pressure force (such as stamping, riveting, and pressure testing), but the conventional air source pressure (usually 0.4-1.0 MPa) is difficult to meet the demand. If a high-pressure hydraulic system is independently configured, it will face problems such as complex structure, high cost, large space occupation and high energy consumption. Booster cylinders, as a pneumatic-hydraulic integrated component, effectively solve this contradiction by integrating the advantages of pneumatic and hydraulic transmission.

 

Different from ordinary air cylinders and hydraulic cylinders, booster cylinders use low-pressure compressed air as the power source, and through the area difference between the pneumatic piston and the hydraulic piston, the low-pressure air pressure is converted into high-pressure hydraulic force, realizing high-pressure output with low energy consumption. Compared with independent hydraulic systems, booster cylinders have the advantages of compact structure, low cost, fast response, no need for independent hydraulic pumps and oil tanks, and easy installation and maintenance; compared with ordinary air cylinders, they have the characteristics of large output force, stable pressure retention and high control precision. These advantages make booster cylinders widely used in machinery manufacturing, automotive production, electronic equipment, aerospace and other fields.

 

At present, there are various types of booster cylinders on the market, and their structural forms, pressure boosting ratios and application scenarios vary greatly. For practitioners, a systematic understanding of the working principles, structural characteristics, application scenarios and maintenance methods of booster cylinders is the basis for rational selection, standardized application and fault handling. This paper focuses on the core technology of booster cylinders, systematically sorts out the working principles, classification, application scenarios and maintenance guides, and combines industry standards and practical engineering experience to provide a comprehensive technical analysis, helping practitioners avoid technical mistakes and improve the efficiency and reliability of equipment operation.

 

 

 

Booster cylinders are typical pneumatic-hydraulic integrated components, whose core is to realize energy conversion and pressure boosting through the coordination of pneumatic and hydraulic components. Their structural composition is more complex than that of ordinary air cylinders, mainly including pneumatic components, hydraulic components, sealing components and auxiliary components. The working principle is based on Pascal’s Law and the area ratio principle of pistons, realizing the conversion from low-pressure air to high-pressure hydraulic oil.

 

 

The typical structure of a booster cylinder includes pneumatic part, hydraulic part, sealing system and auxiliary components. Each part cooperates closely to ensure the normal operation of pressure boosting, pressure retention and reset. The specific composition is as follows:

 

- Pneumatic Part: The power source part of the booster cylinder, mainly including pneumatic cylinder barrel, pneumatic piston, air inlet/outlet port, and reset spring. The pneumatic cylinder barrel is usually made of aluminum alloy or carbon steel, with high rigidity and pressure-bearing capacity, used to accommodate the pneumatic piston and low-pressure compressed air. The pneumatic piston is connected with the hydraulic piston through a piston rod, and under the action of low-pressure air, it drives the hydraulic piston to move to realize pressure boosting. The reset spring is used to reset the pneumatic piston and hydraulic piston after the pressure boosting is completed.

 

- Hydraulic Part: The high-pressure output part of the booster cylinder, mainly including hydraulic cylinder barrel, hydraulic piston, hydraulic oil cavity, oil inlet/outlet port, and one-way valve. The hydraulic cylinder barrel is made of high-strength alloy steel (such as 40Cr, 35CrMo) to withstand high hydraulic pressure (usually 10-100 MPa). The hydraulic piston is closely matched with the hydraulic cylinder barrel, and the area of the hydraulic piston is smaller than that of the pneumatic piston, so as to realize pressure boosting through the area ratio. The one-way valve is used to prevent the backflow of hydraulic oil and ensure stable pressure retention.

 

- Sealing System: The key to ensuring the sealing performance of the booster cylinder, including pneumatic seals (between the pneumatic piston and the pneumatic cylinder barrel), hydraulic seals (between the hydraulic piston and the hydraulic cylinder barrel), and static seals (between the cylinder barrel and the end cover). The pneumatic seals are usually made of nitrile rubber (NBR) or fluorine rubber (FKM), which have good air tightness and wear resistance; the hydraulic seals are made of high-pressure resistant materials (such as PTFE composite seals), which can withstand high hydraulic pressure and avoid oil leakage.

 

- Auxiliary Components: Including pressure relief valve, pressure gauge, oil filter, and mounting bracket. The pressure relief valve is used to release the high-pressure hydraulic oil in the hydraulic cavity after the work is completed, so as to realize the reset of the piston; the pressure gauge is used to monitor the working pressure of the booster cylinder in real time, ensuring that the pressure is within the design range; the oil filter is used to filter the hydraulic oil, prevent impurities from entering the hydraulic cavity, and avoid wear of components; the mounting bracket is used to fix the booster cylinder to the equipment.

 

 

The working principle of booster cylinders is based on the area ratio principle of pistons and Pascal’s Law, and the core is to convert low-pressure air pressure into high-pressure hydraulic force through the area difference between the pneumatic piston and the hydraulic piston. The pressure boosting ratio is determined by the area ratio of the two pistons, and the specific working process is divided into three stages: pressure boosting stage, pressure retention stage and reset stage.

 

 

When low-pressure compressed air (0.4-1.0 MPa) enters the pneumatic cavity of the booster cylinder through the air inlet port, the air pressure acts on the end face of the pneumatic piston, generating a thrust force F1 = P1 × A1 (where P1 is the pressure of the compressed air, A1 is the effective acting area of the pneumatic piston). Under the action of this thrust force, the pneumatic piston drives the hydraulic piston (connected by the piston rod) to move downward, compressing the hydraulic oil in the hydraulic cavity. According to Pascal’s Law, the pressure acting on the hydraulic piston is transmitted equally to all parts of the hydraulic oil, generating a high-pressure output force F2 = P2 × A2 (where P2 is the high-pressure hydraulic pressure, A2 is the effective acting area of the hydraulic piston).

 

Since the thrust force generated by the pneumatic piston is equal to the resistance force of the hydraulic piston (F1 = F2), the pressure boosting ratio K = P2 / P1 = A1 / A2. It can be seen that the larger the area ratio of the pneumatic piston to the hydraulic piston, the higher the pressure boosting ratio. For example, if the area ratio A1/A2 = 10, and the input air pressure P1 = 0.6 MPa, the output hydraulic pressure P2 = 6 MPa, realizing a 10-fold pressure boost.

 

 

When the output hydraulic pressure reaches the set value (monitored by the pressure gauge), the air source is cut off, and the one-way valve in the hydraulic cavity closes automatically, preventing the backflow of hydraulic oil. At this time, the booster cylinder enters the pressure retention stage, and the hydraulic pressure can be stably maintained for a certain period of time (usually several minutes to several hours, depending on the sealing performance). The pressure retention performance is an important index of the booster cylinder, which is mainly determined by the sealing performance of the hydraulic seals and the one-way valve.

 

 

After the work is completed (such as stamping, riveting), the pressure relief valve is opened, and the high-pressure hydraulic oil in the hydraulic cavity is released to the oil tank. At this time, the reset spring in the pneumatic cavity pushes the pneumatic piston and hydraulic piston to reset upward, and the air in the pneumatic cavity is discharged through the air outlet port. After reset, the booster cylinder is in a standby state, waiting for the next pressure boosting cycle.

 

 

According to the structural form and working mode, booster cylinders can be divided into two main types: single-acting booster cylinders and double-acting booster cylinders. Each type has its own unique structural characteristics and applicable scenarios:

 

- Single-Acting Booster Cylinders: Only one direction of pressure boosting is driven by compressed air, and the reset is realized by the reset spring. The structure is simple, compact, low cost, and suitable for scenarios requiring unidirectional high-pressure force (such as stamping, riveting, and clamping). The disadvantage is that the reset force is limited by the spring, and the reset speed is relatively slow.

 

- Double-Acting Booster Cylinders: Both pressure boosting and reset are driven by compressed air, without the need for a reset spring. The pressure boosting and reset speeds are fast, the output force is stable, and the pressure retention performance is better. It is suitable for scenarios requiring high efficiency, frequent operation, and bidirectional high-pressure force (such as automatic stamping lines, continuous riveting equipment, and pressure testing machines). The disadvantage is that the structure is relatively complex and the cost is higher than that of single-acting booster cylinders.

 

 

 

Booster cylinders are mainly used in industrial scenarios requiring high pressure, small stroke, fast response and clean environment. They can replace traditional high-pressure hydraulic systems, reduce equipment cost and energy consumption, and improve production efficiency. Their application fields cover machinery manufacturing, automotive production, electronic equipment, aerospace, medical equipment and other industries. The specific application scenarios are as follows:

 

 

The machinery manufacturing field is the largest application field of booster cylinders, mainly used in stamping, riveting, bending, cutting and clamping processes, especially suitable for small and medium-sized equipment that requires high pressure but cannot configure independent hydraulic systems.

 

- Stamping and Punching: Used in small stamping machines, punching machines and blanking machines to provide high-pressure stamping force, realizing the stamping and forming of metal sheets, plastic parts and other workpieces. For example, in the production of hardware accessories, booster cylinders are used to punch holes and shape metal sheets, which has the advantages of fast speed, stable force and low energy consumption.

 

- Riveting and Riveting: Used in riveting equipment to provide high-pressure riveting force, realizing the connection of workpieces (such as riveting of sheet metal, riveting of electronic components). For example, in the production of auto parts, booster cylinders are used to rivet the connecting parts of the body, ensuring the firmness of the connection.

 

- Workpiece Clamping: Used in machining centers, CNC machine tools and other equipment to clamp workpieces with high pressure, ensuring the stability of the workpiece during processing. For example, in the machining of precision parts, booster cylinders are used to clamp the workpiece, preventing displacement during processing and improving processing precision.

 

 

The automotive production field has high requirements for production efficiency and product quality, and booster cylinders are widely used in various links of automotive production, such as body processing, component assembly and testing.

 

- Automotive Body Processing: Used in the stamping and riveting of automotive body parts, such as the stamping of door panels, fenders and the riveting of body frames. Booster cylinders can provide stable high pressure, ensuring the shape accuracy and connection firmness of body parts.

 

- Automotive Component Assembly: Used in the assembly of automotive components, such as the press-fitting of bearings, bushings and gears, and the riveting of connectors. For example, in the assembly of automotive engines, booster cylinders are used to press-fit the bearing into the engine housing, ensuring the fit accuracy.

 

- Automotive Testing: Used in automotive component pressure testing, such as the pressure testing of brake pipes, fuel pipes and hydraulic cylinders. Booster cylinders can provide stable high pressure, detecting whether the components have leakage and pressure-bearing performance defects.

 

 

In the electronic equipment field, booster cylinders are mainly used in the assembly and testing of precision electronic components, requiring high precision, small volume and clean environment.

 

- Electronic Component Assembly: Used in the press-fitting and riveting of electronic components, such as the press-fitting of integrated circuits, resistors and capacitors, and the riveting of connectors. Booster cylinders with small volume and high precision can avoid damage to precision components while providing sufficient pressure.

 

- Electronic Equipment Testing: Used in the pressure testing of electronic equipment shells, connectors and other components, ensuring that the components can withstand a certain pressure without damage. For example, in the testing of mobile phone shells, booster cylinders are used to test the pressure-bearing performance of the shell, ensuring that it is not easily deformed.

 

 

In the aerospace field, booster cylinders are used in the assembly and testing of aerospace components, requiring high reliability, high precision and strong environmental adaptability (high temperature, low temperature, high pressure).

 

- Aerospace Component Assembly: Used in the press-fitting and riveting of aerospace components, such as the assembly of aircraft engine components, aircraft body connectors. Booster cylinders with high pressure stability and precision can ensure the assembly quality of components.

 

- Aerospace Component Testing: Used in the pressure testing of aerospace components, such as the pressure testing of aircraft hydraulic pipelines, fuel tanks. Booster cylinders can provide high-pressure and stable pressure output, detecting the pressure-bearing performance and sealing performance of components.

 

 

In addition to the above fields, booster cylinders are also widely used in medical equipment, food processing, mold manufacturing and other fields:

 

- Medical Equipment: Used in the assembly and testing of medical equipment, such as the press-fitting of medical instruments, the pressure testing of medical pipelines. Booster cylinders with clean and pollution-free characteristics can meet the hygiene requirements of medical equipment.

 

- Food Processing: Used in the packaging and processing of food, such as the pressure sealing of food packaging bags, the pressing of food molds. Booster cylinders with clean and non-toxic characteristics can avoid pollution to food.

 

- Mold Manufacturing: Used in the mold clamping and demolding of injection molds, die-casting molds, providing high-pressure clamping force, ensuring the precision of mold closing and the quality of mold products.

 

 

 

Booster cylinders are pneumatic-hydraulic integrated components, and their maintenance is more complex than that of ordinary air cylinders. Regular and standardized maintenance can effectively reduce failures, extend service life, and ensure stable pressure boosting performance and pressure retention performance. The maintenance of booster cylinders mainly includes daily inspection, regular maintenance, fault diagnosis and handling.

 

 

Daily inspection is the basis for ensuring the normal operation of booster cylinders, mainly focusing on air tightness, oil tightness, pressure stability and abnormal phenomena. The specific inspection content is as follows:

 

- Air Tightness Inspection: Check the air inlet/outlet port, pneumatic cylinder barrel and end cover for air leakage. Use soapy water to apply to the connection parts, and check for bubble generation. If there is air leakage, tighten the connection bolts or replace the pneumatic seals in time.

 

- Oil Tightness Inspection: Check the hydraulic cylinder barrel, oil inlet/outlet port, one-way valve and pressure relief valve for oil leakage. If there is oil leakage, check whether the hydraulic seals are worn or damaged, and replace them in time; check whether the connection parts are loose, and tighten them.

 

- Pressure Stability Inspection: Start the booster cylinder, monitor the pressure gauge, and check whether the output pressure is stable and whether it meets the set value. If the pressure fluctuates greatly or cannot reach the set value, check the one-way valve, pressure relief valve and air source pressure.

 

- Abnormal Phenomenon Inspection: Check whether the booster cylinder has abnormal noise, vibration or overheating during operation. If there is abnormal noise, check whether the piston rod is stuck or the lubrication is insufficient; if there is overheating, check whether the hydraulic oil is deteriorated or the cooling system is faulty.

 

 

Regular maintenance is to comprehensively inspect and maintain the booster cylinder, eliminate potential faults, and ensure long-term stable operation. The maintenance cycle is determined according to the frequency of use and working environment, and the specific content is as follows:

 

 

- Clean the surface of the booster cylinder, remove dust, oil stains and other impurities, and check the appearance for scratches, corrosion and deformation.

 

- Check the oil level and oil quality of the hydraulic oil. If the oil level is lower than the specified value, add the same type of hydraulic oil; if the hydraulic oil is discolored, emulsified or contains impurities, replace the hydraulic oil in time.

 

- Check the one-way valve and pressure relief valve for blockage, and clean them if necessary. Ensure that the valve core moves flexibly and the sealing performance is good.

 

- Check the reset spring for fatigue, deformation or breakage, and replace it if necessary.

 

 

- Disassemble the booster cylinder, check the wear of the pneumatic piston, hydraulic piston and piston rod. If there is severe wear, scratches or corrosion, repair or replace them.

 

- Check the wear of the pneumatic seals and hydraulic seals, and replace all seals if they are worn, aged or damaged. When replacing, select seals that match the model and pressure level of the booster cylinder.

 

- Clean the hydraulic cavity and pneumatic cavity, remove impurities and carbon deposits, and ensure the smoothness of the inner wall.

 

- Check the connection bolts and nuts for looseness, and tighten them. Apply anti-rust oil to the bolts to prevent rust.

 

 

- Comprehensively inspect the structural parts of the booster cylinder, such as the cylinder barrel, piston rod and end cover, for cracks, deformation and other defects. If there are defects, repair or replace them.

 

- Calibrate the pressure gauge and pressure relief valve to ensure the accuracy of pressure measurement and pressure control.

 

- Replace the hydraulic oil and clean the oil filter to ensure the cleanliness of the hydraulic system.

 

- Perform a full-load test on the booster cylinder, check the pressure boosting ratio, pressure retention performance and reset performance, and adjust and repair if necessary.

 

 

In the process of using booster cylinders, common faults include insufficient output pressure, unstable pressure retention, oil leakage, air leakage, and piston jamming. The following summarizes the causes and handling methods of common faults:

 

- Fault 1: Insufficient Output Pressure

 

  - Causes: Low air source pressure, blockage of the one-way valve, wear of the hydraulic piston or seals, incorrect area ratio of the piston, and insufficient hydraulic oil.

 

  - Handling Methods: Adjust the air source pressure to the specified range; clean the one-way valve to remove blockages; replace the worn hydraulic piston or seals; check the piston area ratio and adjust if necessary; add hydraulic oil to the specified level.

 

- Fault 2: Unstable Pressure Retention

 

  - Causes: Wear or damage of hydraulic seals, leakage of the one-way valve, loose connection of the hydraulic pipeline, and deterioration of hydraulic oil.

 

  - Handling Methods: Replace the worn or damaged hydraulic seals; repair or replace the one-way valve; tighten the hydraulic pipeline connection; replace the hydraulic oil.

 

- Fault 3: Oil Leakage

 

  - Causes: Wear or damage of hydraulic seals, loose connection of the oil inlet/outlet port, cracks in the hydraulic cylinder barrel, and excessive hydraulic oil pressure.

 

  - Handling Methods: Replace the hydraulic seals; tighten the connection of the oil inlet/outlet port; repair or replace the hydraulic cylinder barrel with cracks; adjust the hydraulic oil pressure to the specified range.

 

- Fault 4: Air Leakage

 

  - Causes: Wear or damage of pneumatic seals, loose connection of the air inlet/outlet port, cracks in the pneumatic cylinder barrel, and excessive air source pressure.

 

  - Handling Methods: Replace the pneumatic seals; tighten the connection of the air inlet/outlet port; repair or replace the pneumatic cylinder barrel with cracks; adjust the air source pressure to the specified range.

 

- Fault 5: Piston Jamming

 

  - Causes: Impurities entering the cylinder barrel, wear or deformation of the piston rod, insufficient lubrication, and misalignment of the piston.

 

  - Handling Methods: Disassemble the booster cylinder, clean the cylinder barrel and piston, remove impurities; repair or replace the worn or deformed piston rod; add lubricating oil to the moving parts; adjust the piston alignment to ensure smooth movement.

 

 

- Before maintenance, must cut off the air source and hydraulic source, release the pressure in the cylinder barrel, and ensure that the booster cylinder is in a pressure-free state to avoid safety accidents.

 

- When disassembling and assembling the booster cylinder, use special tools to avoid damaging the components (such as piston, piston rod, seals).

 

- When replacing seals, select seals that match the model, pressure level and working temperature of the booster cylinder, and ensure that the seals are installed correctly.

 

- The hydraulic oil used must meet the specified grade and cleanliness requirements, and different types of hydraulic oil cannot be mixed.

 

- After maintenance, perform a test run to check whether the booster cylinder operates normally, whether the pressure is stable, and whether there is leakage before putting it into use.

 

 

 

Booster cylinders, as a key pneumatic-hydraulic integrated component, integrate the advantages of pneumatic and hydraulic transmission, and realize the conversion from low-pressure air to high-pressure hydraulic force through the area ratio principle of pistons. They have the characteristics of compact structure, energy saving, high efficiency, reliable operation and low cost, and are widely used in various industrial fields requiring high pressure and small stroke, such as machinery manufacturing, automotive production, electronic equipment and aerospace.

 

This paper systematically elaborates on the structural composition and core working principles of booster cylinders, clarifies the pressure boosting mechanism and working process of different types of booster cylinders; deeply explores the application scenarios of booster cylinders in various industries, and combines practical scenarios to illustrate their application advantages and key points; finally, summarizes the standardized maintenance methods of booster cylinders, including daily inspection, regular maintenance, fault diagnosis and handling, providing comprehensive and professional technical guidance for relevant practitioners.

 

In the actual application process, it is necessary to select the appropriate type of booster cylinder according to the working conditions (pressure, stroke, frequency of use) and performance requirements, and strictly follow the maintenance guide to carry out daily maintenance and regular maintenance, so as to ensure the stable operation of the booster cylinder and extend its service life. In the future, with the continuous development of pneumatic-hydraulic integration technology, booster cylinders will develop towards higher pressure, higher precision, faster response and intelligence, expanding their application scope to more high-end industrial fields. For practitioners, it is necessary to continuously learn new technologies and new standards, accumulate practical experience, and improve the level of selection, application and maintenance of booster cylinders to meet the growing industrial demand.