High-precision low-friction pneumatic actuator

Abstract

A high-precision low-friction pneumatic actuator comprises a cylinder body, an upper cylinder cover is arranged at the upper end of the cylinder body, a lower cylinder cover is arranged at the lower end of the cylinder body, a piston is arranged in the cylinder body, and a first rolling guide belt and a first Glyd sealing ring are arranged between the outer side face of the piston and the inner side face of the cylinder body. A first sealing groove for installing a first Glyd sealing ring is formed in the outer side face of the piston, a piston rod is connected to the lower side of the piston, and a second rolling guide belt, a second Glyd sealing ring and a dustproof ring are sequentially arranged between the outer side face of the piston rod and the inner side face of the lower cylinder cover from top to bottom. A bearing friction piece is changed into a rolling guide belt, sliding friction between moving pieces is changed into rolling friction of steel balls, the friction coefficient is reduced by one order of magnitude, and the moving friction resistance of the moving pieces is greatly reduced; meanwhile, due to the arrangement continuity of the steel balls, high precision between moving parts is guaranteed. The Glyd sealing ring has the characteristics of low friction coefficient, long service life, small motion resistance and the like.

Description

Technical Field

[0001] The utility model relates to the field of machinery, in particular to a low-friction rolling structure with ball rotation, and especially to a pneumatic actuator with high precision and low friction. Background Art

[0002] In the prior art, pneumatic piston-type cylinder actuators supporting large-caliber flow regulating valves generally have defects such as large movement frictional resistance, low control precision, short service life, large dead zone, large hysteresis, and large backlash. Especially when the flow rate of the regulating valve changes greatly and the pressure difference changes greatly, the flow regulating valve acts frequently. Therefore, the regulating effect of the pneumatic actuator is poor and cannot meet the requirements of the increasingly developed automatic control of process pipelines. Summary of the Invention

[0003] The purpose of the utility model is to provide a pneumatic actuator with high precision and low friction, and the pneumatic actuator with high precision and low friction is to solve the technical problems of large movement frictional resistance, low control precision, and short service life of the pneumatic actuator in the prior art.

[0004] A pneumatic actuator with high precision and low friction of the utility model includes a cylinder body. An upper cylinder cover is arranged at the upper end of the cylinder body, a lower cylinder cover is arranged at the lower end of the cylinder body, a piston is arranged in the cylinder body. A first rolling guide belt and a first Gleit ring seal are arranged between the outer side surface of the piston and the inner side surface of the cylinder body. The first Gleit ring seal is located below the first rolling guide belt. A first seal groove for installing the first Gleit ring seal is arranged on the outer side surface of the piston. A piston rod is connected to the lower side of the piston. The piston rod passes through the lower cylinder cover downward. A second rolling guide belt, a second Gleit ring seal, and a dust seal are sequentially arranged from top to bottom between the outer side surface of the piston rod and the inner side surface of the lower cylinder cover. A second seal groove for installing the second Gleit ring seal is arranged on the outer side surface of the piston rod. Chromium plating layers are arranged on the inner side surface of the cylinder body, the lower cylinder cover, and the outer side surface of the piston rod.

[0005] Further, first sealing rings are arranged between the upper cylinder cover, the lower cylinder cover and the cylinder body.

[0006] Further, a second sealing ring is arranged between the piston rod and the piston.

[0007] Further, a guide ring is arranged on the outer circumference of the piston.

[0008] Further, each of the first rolling guide belt and the second rolling guide belt includes an annular cage. A plurality of continuous steel balls are arranged in the cage. A spiral circulation track for cooperating with the steel balls is arranged on the outer circumference of the cage.

[0009] Further, a spring is arranged between the piston and the upper cylinder cover.

[0010] Compared with the prior art, the effects of the present utility model are positive and obvious.

[0011] 1) The cylinder block, piston rod, etc. are made of stainless steel materials processed by precision rolling. Their surfaces are all chrome-plated to improve wear resistance and hardness, with low surface roughness. The bearing friction parts are changed to rolling guide belts (ball moving components), and the sliding friction between moving parts is changed to the rolling friction of steel balls. The friction coefficient is reduced by an order of magnitude, greatly reducing the movement friction resistance of the moving parts. At the same time, due to the continuity of the steel ball arrangement, the high precision between moving parts is ensured.

[0012] 2) The piston seal assembly and the piston rod seal assembly are the first Gleit ring and the second Gleit ring respectively. Compared with ordinary O-ring seal elements, since the moving contact parts of the Gleit ring are made of arc-shaped tetrafluoro materials, they have the characteristics of low friction coefficient, high service life, and small movement resistance.

[0013] 3) The Gleit ring and the rolling guide belt are used in combination with the valve positioner, having significant advantages such as small dead zone, small hysteresis, and small backlash. The precision is equivalent to that of the diaphragm actuator, and the service life is much higher than that of the diaphragm actuator. Description of the Drawings

[0014] Figure 1 It is a schematic diagram of a high-precision and low-friction pneumatic actuator of the present utility model.

[0015] Figure 2 It is a schematic diagram of the rolling guide belt in a high-precision and low-friction pneumatic actuator of the present utility model. Detailed Embodiments

[0016] The present utility model will be further described below in conjunction with embodiments, but the present utility model is not limited to these embodiments. All similar structures and similar changes using the present utility model should be included in the protection scope of the present utility model. The use of directions such as up, down, front, back, left, and right in the present utility model is only for the convenience of clear description and is not a limitation to the technical solution of the present utility model.

[0017] Such as Figure 1 And Figure 2As shown in the figure, a pneumatic actuator with high precision and low friction of the present utility model includes a cylinder block 12. An upper cylinder head 14 is provided at the upper end of the cylinder block 12, and a lower cylinder head 5 is provided at the lower end of the cylinder block 12. A piston 10 is arranged in the cylinder block 12. A first rolling guide belt 7 and a first Gleitring seal 6 are arranged between the outer side surface of the piston 10 and the inner side surface of the cylinder block 12. The first Gleitring seal 6 is located below the first rolling guide belt 7. A first sealing groove for installing the first Gleitring seal 6 is arranged on the outer side surface of the piston 10. A piston rod 1 is connected to the lower side of the piston 10. The piston rod 1 passes downward through the lower cylinder head 5. A second rolling guide belt 4, a second Gleitring seal 3 and a dust seal 2 are sequentially arranged from top to bottom between the outer side surface of the piston rod 1 and the inner side surface of the lower cylinder head 5. A second sealing groove for installing the second Gleitring seal 3 is arranged on the outer side surface of the piston rod 1. Chrome plating layers are arranged on the inner side surfaces of the cylinder block 12 and the lower cylinder head 5 and the outer side surface of the piston rod 1.

[0018] Furthermore, first sealing rings 13 are arranged between the upper cylinder head 14, the lower cylinder head 5 and the cylinder block 12.

[0019] Furthermore, a second sealing ring 8 is arranged between the piston rod 1 and the piston 10.

[0020] Furthermore, a guide ring 9 is arranged on the outer periphery of the piston 10.

[0021] Furthermore, each of the first rolling guide belt 7 and the second rolling guide belt 4 includes an annular cage 15. A plurality of continuous steel balls 16 are arranged in the cage 15. A spiral circulating track 17 matched with the steel balls 16 is arranged on the outer periphery of the cage 15.

[0022] Furthermore, a spring 11 is arranged between the piston 10 and the upper cylinder head 14.

[0023] Specifically, the cylinder block 12, the upper cylinder head 14, the lower cylinder head 5, the rolling guide belt, the Gleitring seal, the chrome plating layer, the guide ring 9, the cage 15, the steel balls 16, the spiral circulating track 17, the spring 11, etc. in this embodiment all adopt well-known solutions in the prior art, which are all understood by those skilled in the art and will not be elaborated here.

[0024] The present utility model is a new structure with low friction of a high-precision pneumatic actuator, and the main improvement points are as follows:

[0025] 1) The cylinder block 12, the piston rod 1, etc. adopt stainless steel materials processed by precision rolling. Their surfaces are all chrome plated to improve wear resistance and hardness, with low surface roughness. The bearing friction parts are changed to rolling guide belts (ball moving components), and the sliding friction between moving parts is changed to the rolling friction of the steel balls 16. The friction coefficient is reduced by an order of magnitude, greatly reducing the movement friction resistance of the moving parts; at the same time, due to the continuity of the arrangement of the steel balls 16, the high precision between moving parts is ensured.

[0026] 3) The piston seal assembly and the piston rod seal assembly are respectively the first Gleit ring 6 and the second Gleit ring 3. Compared with ordinary O-ring seal elements, since the moving contact part of the Gleit ring is made of arc-shaped tetrafluoro material, it has the characteristics of low friction coefficient, high service life, and small movement resistance.

[0027] 3) The Gleit ring and the rolling guide band are used in combination with the valve positioner, which has significant advantages such as small dead zone, small hysteresis, and small backlash. The accuracy is equivalent to that of the diaphragm actuator, and the service life is much higher than that of the diaphragm actuator.

[0028] The working principle of this embodiment:

[0029] 1. Introduction to the principle of the ball moving assembly:

[0030] The principle of the ball moving assembly is divided into two types: hole type and shaft type. Taking the shaft type ball moving assembly as an example, its structure is that a cage 15 made of copper alloy or plastic is installed inside the outer ring. A continuous number of steel balls 16 are installed inside the cage 15. There is an outer circulation pipeline outside the outer ring, which connects the inlet and outlet of the cage 15. When the piston rod 1 moves back and forth, the steel balls 16 in the cage 15 and the spiral circulation track 17 make a circulating rolling motion. The two ends of the cage 15 are fixed by the inner side edges at both ends of the outer ring. The steel balls 16 move along the spiral circulation track 17 of the cage 15. The spiral circulation track 17 under stress makes the steel balls 16 bearing the pressure load make rolling contact with the outer circle of the piston rod 1. Since the movement of the steel balls 16 is rolling friction, and the rolling friction coefficient is about 0.01. During the relative rolling movement process, due to the high hardness and smooth surface of the moving surface, the friction resistance is extremely small and changes little. Compared with the dynamic friction coefficient of sliding friction being 0.3 - 0.4 and the static friction coefficient reaching 0.6 - 0.7, the value is small and the change is small. Therefore, the rolling friction resistance changes little, and the accuracy can be maintained unchanged for a long time, and the service life is long. At the same time, even a very small pressure output of the valve positioner can bring a rapid response, and the accuracy such as the dead zone and backlash of the actuator has been improved. In addition, the lubrication of the ball moving assembly is simple. Only an oil mist separator needs to be added at the filter pressure reducing valve when compressed air is input. Oil is supplied by adding lubricating oil to the instrument compressed air, and the lubrication and maintenance are simple and easy to maintain.

[0031] 2. The piston rod 1 and the piston seal assembly have two types: hole type and shaft type. The first seal groove and the second seal groove are respectively machined, and the first Gleit ring 6 and the second Gleit ring 3 are installed. The Gleit ring is composed of an O-ring and a polytetrafluoroethylene ring. The sealing power of the Gleit ring is the compression force of the O-ring. The polytetrafluoroethylene ring contacts the surface of the cylinder block 12 or the piston rod 1 and maintains a sliding movement. Due to the low friction and wear resistance of the polytetrafluoroethylene ring, the effects of maintaining sealing, extremely small friction resistance, and smooth movement are achieved.

[0032] 3. The sealing surfaces of the cylinder block 12 and the lower cylinder head 5 are plated with electroless nickel layers, which produce a hard wear-resistant layer on the surfaces in contact with the Gle seal ring, thereby increasing the surface hardness and achieving the purpose of wear resistance. The cylinder can still maintain its service performance after being cycled 500,000 times, and the operation is stable and reliable.

[0033] 4. Compared with the friction coefficient of ordinary rubber seals being 0.3 - 0.7, the friction coefficient of the polished metal against the Gle seal ring is 0.1 - 0.15. The frictional force is small and the change range is also small, enabling stable frictional resistance to be controlled.

[0034] 5. Due to the adoption of the rolling guide belt and the Gle seal ring, this high-precision piston-type cylinder actuator has the characteristics of low dead zone and small hysteresis. Therefore, it can withstand a gas source pressure of 6 - 8 Bar, has a large output force, and is an ideal pneumatic actuator for large-bore control valves requiring high dynamic precision.

[0035] In summary, the high-precision and low-friction cylinder actuator of the present utility model has small moving frictional resistance, high control precision, long service life, small dead zone, reliable sealing, and a wide range of applications.

Claims

1. A pneumatic actuator with high precision and low friction, comprising a cylinder block, characterized in that: An upper cylinder head is provided at the upper end of the cylinder block, a lower cylinder head is provided at the lower end of the cylinder block, a piston is arranged in the cylinder block, a first rolling guide belt and a first Gleitring seal are arranged between the outer side surface of the piston and the inner side surface of the cylinder block, the first Gleitring seal is located below the first rolling guide belt, a first seal groove for installing the first Gleitring seal is arranged on the outer side surface of the piston, a piston rod is connected to the lower side of the piston, the piston rod passes downward through the lower cylinder head, a second rolling guide belt, a second Gleitring seal and a dust seal are sequentially arranged from top to bottom between the outer side surface of the piston rod and the inner side surface of the lower cylinder head, a second seal groove for installing the second Gleitring seal is arranged on the outer side surface of the piston rod, and chromium plating layers are arranged on the inner side surfaces of the cylinder block and the lower cylinder head and the outer side surface of the piston rod.

2. The pneumatic actuator with high precision and low friction according to claim 1, characterized in that: First seals are arranged between the upper cylinder head, the lower cylinder head and the cylinder block.

3. A high-precision and low-friction pneumatic actuator according to claim 1, characterized in that: A second seal is arranged between the piston rod and the piston.

4. A high-precision and low-friction pneumatic actuator according to claim 1, characterized in that: A guide ring is arranged on the outer periphery of the piston.

5. A high-precision and low-friction pneumatic actuator according to claim 1, characterized in that: Each of the first rolling guide belt and the second rolling guide belt includes an annular cage, a plurality of continuous steel balls are arranged in the cage, and a spiral circulation track for cooperating with the steel balls is arranged on the outer periphery of the cage.

6. A high-precision and low-friction pneumatic actuator according to claim 1, characterized in that: A spring is arranged between the piston and the upper cylinder head.

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