Double-acting air floatation cylinder integrated with position sensing

Abstract

A double-acting air floatation air cylinder integrating position sensing comprises a cylinder body A, a cylinder body B, a piston assembly, an air floatation shaft sleeve A and an air floatation shaft sleeve B, the cylinder body A is fixedly connected with the cylinder body B, the air floatation shaft sleeve A is arranged in the cylinder body A, and the air floatation shaft sleeve B is arranged in the cylinder body B; a first air supply hole and an air floatation shaft sleeve A air supply port are formed in the surface of the cylinder body A; a second air supply hole and an air floatation shaft sleeve B air supply port are formed in the surface of the cylinder body B; the piston assembly comprises a piston rod and a piston, the piston rod slides in the rod cavity and penetrates through the air floatation shaft sleeve A, and the piston slides in the rod cavity and the rodless cavity and penetrates through the air floatation shaft sleeve B; the air floating shaft sleeve B is of an annular structure with a cavity, and a plurality of throttling holes communicated with the cavity are distributed in the inner surface of the air floating shaft sleeve B; a position sensor for feeding back the piston position in real time is arranged at the tail end of the cylinder body B. The air floating shaft sleeve is additionally arranged in the cylinder barrel, so that an air film is generated between the piston and the air floating shaft sleeve, and friction-free relative movement is achieved in the operation process of the piston assembly.

Description

Technical Field

[0001] This invention relates to the field of pneumatic actuators, and in particular to a double-acting air-floating cylinder with integrated position sensing. Background Technology

[0002] Pneumatic systems use compressed air as the medium for transmitting energy and signals and are widely used in the industrial field. As the core actuator of this system, the cylinder, with its advantages of simple structure and clean, pollutant-free emissions, performs exceptionally well in precision grinding and machining applications. It is particularly suitable for processing brittle materials such as cast iron, glass, and ceramics, as its smooth, continuous, and precisely controllable motion characteristics can meet the stringent requirements of processing these materials.

[0003] Traditional cylinders suffer from uncertain friction that varies with operating conditions, directly hindering the improvement of output force control precision. To address this bottleneck, the concept of air-float frictionless cylinders has emerged in recent years. This type of cylinder utilizes a high-pressure air film for lubrication and load-bearing, avoiding direct contact between friction pairs and thus eliminating the interference of friction on output force. This provides a technological possibility for achieving ultra-high precision output force control in cylinders. For example, Chinese invention patent (publication number: CN107830008B) discloses a general-purpose double-acting air-float frictionless cylinder. By incorporating air bearings and an air-float piston, it achieves contactless engagement between the piston rod and the front cover, and between the piston and the cylinder wall, respectively, resulting in frictionless motion.

[0004] However, existing air-float cylinders of this type have structural design flaws: in order to achieve independent air supply to the air-float piston, an air pipe needs to be laid at the front end of the piston rod, which will have an adverse effect on the force servo control accuracy of the cylinder.

[0005] In addition, precision manufacturing scenarios require cylinders to have both high-precision force adjustment and continuous position feedback throughout the entire stroke. Existing external position sensing solutions require additional support or cylinder modification, resulting in structural redundancy and hindering the integrated design of equipment. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention proposes a double-acting air-floating cylinder with integrated position sensing. This is achieved by incorporating an air-floating bushing within the cylinder barrel, creating an air film between the bushing and the piston, thus enabling non-contact air film lubrication. The technical solution used is as follows: A double-acting air-float cylinder with integrated position sensing includes a cylinder body A, a cylinder body B, a piston assembly, an air-float bushing A, and an air-float bushing B; the cylinder body A and the cylinder body B are fixedly connected, the air-float bushing A is disposed inside the cylinder body A, the air-float bushing B is disposed inside the cylinder body B, the cylinder body A has a rod chamber inside, and the cylinder body B has a rodless chamber inside. The cylinder A surface is provided with a first air supply hole and an air supply port for air float sleeve A. The first air supply hole is connected to the rod chamber, and the air supply port for air float sleeve A is connected to air float sleeve A. The cylinder B surface is provided with a second air supply hole and an air supply port for air float sleeve B. The second air supply hole is connected to the rodless chamber, and the air supply port for air float sleeve B is connected to air float sleeve B. The piston assembly includes a piston rod and a piston. The piston rod slides in the rod chamber and passes through the air-bearing bushing A, and the piston slides in the rod chamber and the rodless chamber and passes through the air-bearing bushing B. The air-bearing bushing B is configured as an annular structure with a cavity, and the inner surface of the air-bearing bushing B is distributed with a plurality of throttling holes communicating with the cavity. A position sensor is provided at the end of cylinder B to detect the displacement of the piston in real time.

[0007] Furthermore, cylinder A and cylinder B are respectively provided with axial through holes and threaded holes and are fixedly connected by bolts; a circumferential sealing groove is provided at the connection between cylinder A and cylinder B and a sealing ring is installed; buffer pads are provided at the front end of cylinder A and the end of cylinder B.

[0008] Furthermore, the air-bearing bushing B has sealing grooves on both sides to achieve a seal.

[0009] Furthermore, the air-bearing bushing A adopts a porous structure.

[0010] Furthermore, the air bearing bushing A and the air bearing bushing B are coaxially nested and installed at the front end of cylinder A and cylinder B respectively with an interference fit; the air bearing bushing A is axially limited by the stepped boss inside cylinder A; the air bearing bushing B is doubly limited by the boss inside cylinder B and the end face of cylinder A.

[0011] Furthermore, cylinder A and / or cylinder B are equipped with individually installable permanent magnet modules.

[0012] Furthermore, the piston rod is made of a material with an electrical conductivity of not less than 1×10⁶ S / m.

[0013] Furthermore, the inner surface of the air-bearing bushing B is provided with several pressure equalization grooves, which are located at the end of the throttling orifice.

[0014] Because the present invention adopts the above-described technical solution, the present invention has the following advantages: 1. This invention provides a double-acting air-floating cylinder with integrated position sensing. By adding an air-floating bushing inside the cylinder, an air film is generated between the piston and the air-floating bushing. With the isolation effect of the air film, the piston assembly can achieve contactless and frictionless relative motion during operation, effectively improving the control accuracy of the pneumatic actuator in force servo control scenarios.

[0015] 2. The cylinder body of the present invention is equipped with a position sensor, which can provide real-time feedback on the piston position, track the piston movement speed and stroke for any abnormalities, detect jamming, leakage and other faults in a timely manner, avoid equipment damage, and achieve precise control and status monitoring of the cylinder.

[0016] 3. The inner surface of the air-bearing bushing B of the present invention is provided with a pressure equalization groove, which allows the high-pressure gas ejected from the throttling orifice to diffuse evenly in the groove. The stable pressure distribution can enhance the deformation resistance of the air film, thereby enhancing stability and improving the load-bearing capacity of the bushing. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall internal structure of Embodiment 1 of the present invention.

[0018] Figure 2 This is a schematic diagram of the overall internal structure after permanent magnet A and permanent magnet B are installed in Embodiment 2 of the present invention.

[0019] Figure 3 This is a schematic diagram of the structure of the air-bearing bushing B in Embodiment 1 of the present invention.

[0020] Figure 4 This is a cross-sectional structural diagram of the air-bearing bushing B with a pressure equalization groove in Embodiment 3 of the present invention.

[0021] Figure 5 This is a schematic diagram of the working air circuit of the air-float frictionless pneumatic actuator of the present invention.

[0022] Icon labels: 1-Cylinder A; 11-First air supply port; 12-Air supply port of air-bearing bushing A; 13-Permanent magnet A; 2-Cylinder B; 21-Second air supply port; 22-Air supply port of air-bearing bushing B; 23-Permanent magnet B; 3-Piston assembly; 31-Piston rod; 32-Piston; 4-Air-bearing bushing A; 5-Air-bearing bushing B; 51-Throttle orifice; 52-Sealing groove; 53-Cavity; 54-Pressure equalizing groove; 601-Air source; 602-Pressure reducing valve A; 603-Pressure reducing valve B; 604-Pressure reducing valve C; 605-Pressure stabilizing air tank; 606-Buffer air tank A; 607-Buffer air tank B; 608-Buffer air tank C; 609-Proportional directional valve; 610-Pressure sensor; 611-Industrial computer; 612-Human machine interface terminal; 7-Position sensor. Detailed Implementation

[0023] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention; however, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0024] In the description of this invention, it should be noted that the terms "upper", "lower", "in", "out", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed when in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention. Example 1:

[0025] A double-acting air-float cylinder with integrated position sensing, such as Figure 1 As shown, it includes cylinder block A1, cylinder block B2, piston assembly 3, air bearing sleeve A4 and air bearing sleeve B5; Cylinder block A1 is fixedly connected to cylinder block B2. Air float sleeve A4 is located inside cylinder block A1, and air float sleeve B5 is located inside cylinder block B2. Cylinder block A1 has a rod chamber, and cylinder block B2 has a rodless chamber. More specifically, cylinder block A1 and cylinder block B2 are respectively provided with axial through holes and threaded holes and are fixedly connected by bolts; a circumferential sealing groove is provided at the connection between cylinder block A1 and cylinder block B2 and a sealing ring is installed; buffer pads are provided at the front end of cylinder block A1 and the rear end of cylinder block B2. The cylinder block A1 has a first air supply hole 11 and an air supply port 12 for the air bearing sleeve A. The first air supply hole 11 is connected to the rod chamber, and the air supply port 12 for the air bearing sleeve A is connected to the air bearing sleeve A4. The cylinder block B2 has a second air supply hole 21 and an air supply port 22 for the air bearing sleeve B. The second air supply hole 21 is connected to the rodless chamber, and the air supply port 22 for the air bearing sleeve B is connected to the air bearing sleeve B5. The piston assembly 3 may adopt an integrated stepped shaft structure, including a piston rod 31 and a piston 32. The piston rod 31 slides in the rod chamber and passes through the air-bearing bushing A4, and the piston 32 slides in the rod chamber and the rodless chamber and passes through the air-bearing bushing B5.

[0026] A position sensor 7 is provided at the end of cylinder B2 to detect the displacement of piston 32 in real time. As an example, the position sensor 7 can be a non-contact position sensor commonly used in the prior art, such as the Panasonic HG-C1050 laser position sensor, with a measurement center distance of 50mm and a measurement range of ±15mm.

[0027] like Figure 3As shown, the air bearing sleeve B5 is configured as an annular structure with a cavity 53. Several throttling holes 51 communicating with the cavity 53 are distributed on the inner surface of the air bearing sleeve B5, and the throttling holes 51 extend radially. More specifically, sealing grooves 52 are provided on both sides of the air bearing sleeve B5 to achieve sealing. High-pressure gas is injected into the cavity 53 through the air supply port 22 of the air bearing sleeve B and ejected through the throttling holes 51, forming a gas film on the surface of the piston 32 to achieve zero-friction motion.

[0028] The air-floating bushing A4 uses a porous structure made of metal or ceramic substrate through a precision process, which allows gas to generate an air film inside the air-floating bushing A4, thereby achieving non-contact air film lubrication.

[0029] As a specific implementation of this embodiment, the air bearing sleeve A4 and the air bearing sleeve B5 are coaxially nested and installed at the front end of cylinder A1 and cylinder B2 respectively by interference fit. The air bearing sleeve A4 is axially limited by the stepped boss inside cylinder A1, and the air bearing sleeve B5 is doubly limited by the boss inside cylinder B2 and the end face of cylinder A1.

[0030] When the air-float frictionless pneumatic actuator is working, air is supplied to air-float bushings A4 and B5 through air supply port 12 of air-float bushing A and air supply port 22 of air-float bushing B, respectively. An air film is formed between piston rod 31 and cylinder A1, and an air film is formed between piston 32 and cylinder B2, thereby achieving frictionless operation. When outputting power, high-pressure compressed air is introduced into the rod chamber through the first air supply port 11 and the gas in the rodless chamber is emptied, which drives the piston assembly 3 to retract. High-pressure compressed air is introduced into the rodless chamber through the second air supply port 21 and the gas in the rod chamber is emptied, which drives the piston assembly 3 to extend, thereby driving the piston assembly 3 to perform reciprocating linear motion.

[0031] The air-float frictionless pneumatic actuator described in this embodiment uses an air circuit connection during operation. Figure 5 Taking this example: Pressure reducing valve A602, pressure stabilizing gas tank 605, proportional directional valve 609, and buffer gas tank C608 are sequentially arranged along the gas transmission direction on the connecting pipeline between gas source 601 and second vent 21; one output of pressure stabilizing gas tank 605 is connected to proportional directional valve 609, and the other output is connected to air supply port 12 of air bearing sleeve A and air supply port 22 of air bearing sleeve B; pressure reducing valve B603 and buffer gas tank A606 are sequentially arranged along the gas transmission direction between pressure stabilizing gas tank 605 and air supply port A of air bearing sleeve A. Between 12, pressure reducing valve C604 and buffer gas tank B607 are sequentially installed between pressure stabilizing gas tank 605 and air supply hole 22 of air bearing sleeve B along the gas supply direction; pressure sensor 610 is used to detect the gas pressure of buffer gas tank C608, and industrial control computer 611 controls the opening of proportional directional valve 609 through pressure signal to control the pressure in rodless chamber; human-machine interface terminal 612 receives the gas pressure transmitted by pressure sensor 610 and exchanges information with industrial control computer 611 to realize equipment control. Example 2:

[0032] The only difference between this embodiment and Embodiment 1 is that a permanent magnet module for achieving non-contact eddy current damping is added. This permanent magnet module can be installed independently. Figure 2 As shown, in this embodiment, permanent magnets A13 and B23 are provided. Permanent magnet A13 is embedded in the assembly gap between air bearing sleeve A4 and cylinder A1, and permanent magnet B23 is installed in the assembly gap between air bearing sleeve B5 and cylinder B2.

[0033] When installing the permanent magnet module, the piston rod 31 is made of a material with an electrical conductivity of not less than 1×106 S / m.

[0034] After eliminating friction, the double-acting air flotation cylinder becomes an underdamped system prone to oscillation. Under the action of permanent magnets A13 and B23, when the piston assembly 3 moves, it will generate electric eddy currents inside and form eddy current damping force, which replaces the damping effect of the original friction force, making the system run more stably. Example 3:

[0035] The only difference between this embodiment and Embodiments 1 and 2 is that the inner surface of the air-bearing bushing B5 in this embodiment is provided with several circumferentially distributed pressure equalization grooves 54. These pressure equalization grooves 54 can be circular, square, or elliptical, and are located at the end of the throttling orifice 51. This embodiment uses six pressure equalization grooves 54 as an example for illustration. Figure 4 As shown, each equalizing groove 54 has several throttling holes 51 arranged axially within it. Figure 4 (Taking three examples for illustration), the equalizing groove 54 allows the high-pressure gas ejected from the throttling orifice 51 to diffuse evenly within the groove, thereby improving the bearing capacity of the bushing.

Claims

1. A double-acting air-float cylinder with integrated position sensing, characterized in that, It includes cylinder A (1), cylinder B (2), piston assembly (3), air bearing sleeve A (4) and air bearing sleeve B (5); cylinder A (1) is fixedly connected to cylinder B (2), air bearing sleeve A (4) is disposed inside cylinder A (1), air bearing sleeve B (5) is disposed inside cylinder B (2), cylinder A (1) has a rod chamber inside, and cylinder B (2) has a rodless chamber inside; The cylinder body A (1) has a first air supply hole (11) and an air supply port (12) for the air bearing sleeve A. The first air supply hole (11) is connected to the rod chamber, and the air supply port (12) for the air bearing sleeve A is connected to the air bearing sleeve A (4). The cylinder body B (2) has a second air supply hole (21) and an air supply port (22) for the air bearing sleeve B. The second air supply hole (21) is connected to the rodless chamber, and the air supply port (22) for the air bearing sleeve B is connected to the air bearing sleeve B (5). The piston assembly (3) includes a piston rod (31) and a piston (32). The piston rod (31) slides in the rod chamber and passes through the air-bearing bushing A (4). The piston (32) slides in the rod chamber and the rodless chamber and passes through the air-bearing bushing B (5). The air-bearing bushing B (5) is configured as an annular structure with a cavity (53), and the inner surface of the air-bearing bushing B (5) is provided with a plurality of throttling holes (51) communicating with the cavity (53). The cylinder B (2) is equipped with a position sensor (7) at its end, which is used to detect the displacement of the piston (32) in real time.

2. The dual-acting air-floating cylinder with integrated position sensing according to claim 1, characterized in that, The cylinder A (1) and the cylinder B (2) are respectively provided with axial through holes and threaded holes and are fixedly connected by bolts; a circumferential sealing groove is provided at the connection between the cylinder A (1) and the cylinder B (2) and a sealing ring is installed; a buffer pad is provided at the front end of the cylinder A (1) and the end of the cylinder B (2).

3. The dual-acting air-floating cylinder with integrated position sensing according to claim 1, characterized in that, The air-bearing bushing B (5) has sealing grooves (52) on both sides to achieve sealing.

4. The dual-acting air-floating cylinder with integrated position sensing according to claim 1, characterized in that, The air-bearing bushing A (4) adopts a porous structure.

5. The dual-acting air-floating cylinder with integrated position sensing according to claim 1, characterized in that, The air-bearing bushing A (4) and the air-bearing bushing B (5) are respectively coaxially nested and installed on the front end of cylinder A (1) and cylinder B (2) with an interference fit; the air-bearing bushing A (4) is axially limited by the stepped boss inside cylinder A (1); the air-bearing bushing B (5) is doubly limited by the boss inside cylinder B (2) and the end face of cylinder A (1).

6. The dual-acting air-floating cylinder with integrated position sensing according to claim 1, characterized in that, The cylinder A (1) and / or cylinder B (2) are equipped with a permanent magnet module that can be installed separately.

7. A double-acting air-floating cylinder with integrated position sensing according to claim 6, characterized in that, The piston rod (31) is made of a material with an electrical conductivity of not less than 1×106 S / m.

8. The dual-acting air-floating cylinder with integrated position sensing according to claim 1, characterized in that, The inner surface of the air-bearing bushing B (5) is provided with several pressure equalization grooves (54), and the pressure equalization grooves (54) are located at the end of the throttling orifice (51).

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