Piston independent pressure control, friction adjustable cylinder

Abstract

A piston-independent pressure-controlled, friction-adjustable cylinder includes a cylinder body and a friction adjustment module. The cylinder body includes a front cylinder cover, a cylinder barrel, a rear cylinder cover, a piston rod, and a float piston. The float piston has a piston cavity, a baffle, a throttling orifice, and a one-way valve inside. The piston rod has an exhaust channel. The friction adjustment module includes a rear piston cover, a friction adjustment slider, a movable inclined surface, a radial expansion ring, and an elastic reset component. The elastic reset component provides preload force, causing the radial expansion ring to contact the inner wall of the cylinder barrel, creating a frictional state. Air supply from the rear end drives the friction adjustment slider to move, causing the radial expansion ring to disengage from the inner wall of the cylinder barrel. The one-way valve controls the timing, allowing the same air supply to form a high-pressure air film through the throttling orifice, achieving a frictionless suspension state. The rear air supply is introduced from the rear cylinder cover via a spiral air pipe, without interfering with the piston rod movement. This design allows for flexible switching between frictional and frictionless operating modes, with a compact structure and simple control.

Description

Technical Field

[0001] This invention relates to the field of cylinder technology, and in particular to a cylinder with independent piston pressure control and adjustable friction. Background Technology

[0002] Pneumatic systems use compressed air as the working medium for energy and signal transmission and control. Cylinders, as the most commonly used actuators in pneumatic systems, are widely applied in industrial automation, robotics, and other fields. However, when a cylinder moves at low speeds, it experiences a "creeping" phenomenon due to friction, which significantly limits its performance and affects the system's control accuracy. In some practical applications, to improve work efficiency, cylinders are often required to possess different characteristics at different stages: when the cylinder rapidly approaches the workpiece, high-precision motion servo control is required, necessitating friction damping; after the cylinder contacts the workpiece, a stable loading force needs to be applied, requiring high-precision output force servo control, which necessitates the elimination of friction.

[0003] While air-bearing frictionless cylinders based on gas lubrication technology can support the piston by forming a high-pressure gas film through a throttling orifice, achieving zero contact between the piston and cylinder and thus meeting the requirements of high-precision force servo control, the lack of necessary damping due to their single frictionless state makes it difficult to achieve stable position servo control during rapid approach to the workpiece. Therefore, how to enable the cylinder to accurately switch between "frictional" and "frictionless" states in different working stages to meet the needs of complex and changing working conditions has become a pressing technical challenge in the pneumatic field.

[0004] To achieve adjustable cylinder friction, researchers have proposed several technical solutions. For example, Chinese patents CN108869445B and CN109083883B propose adjusting friction by inflating and deflating an airbag using a shuttle valve module. However, this airbag structure suffers from slow response, poor airbag durability, and complex valve control logic. Furthermore, supplying air to the air-bearing piston from the piston rod tip affects the installation of the front-end actuator. Chinese patent CN113700697B discloses a friction-adjustable cylinder based on a vacuum generator, which uses vacuum negative pressure to adsorb an elastomer to generate deformation. However, this solution relies on an external vacuum source, increasing system complexity and energy consumption. In addition, Chinese patent CN113700696B proposes a solution that uses a swing cylinder to drive a rotary telescopic mechanism to achieve friction adjustment. Although the structure is ingenious, it has many rotating parts, limited assembly space, and is prone to mechanical interference and wear under high-speed reciprocating motion. Meanwhile, some existing solutions use the depth of the concave hole to limit the friction state, which causes the cylinder stroke to be limited by the piston length, thus restricting the scope of application. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a cylinder with independent piston pressure control and adjustable friction. It innovatively designs a new cylinder piston structure with an adjustable V-shaped sealing groove, solving the problem of "non-adjustable" cylinder friction and enabling controllable switching between the cylinder piston's elastic sealing friction pair and gas-lubricated friction pair. The specific technical solution is as follows: A piston-independent pressure-controlled, friction-adjustable cylinder includes an air-float frictionless cylinder and a friction adjustment module; The air-float frictionless cylinder includes a cylinder front end cover, a cylinder barrel, and a cylinder rear end cover connected in sequence, and a piston rod is slidably installed inside. An air-float piston is fixedly installed on the piston rod and slidably installed inside the cylinder barrel. The outer diameter of the air-float piston is smaller than the inner diameter of the cylinder barrel. The air-float piston divides the inside of the cylinder barrel into a rod chamber and a rodless chamber. The cylinder front end cover is provided with a rod chamber vent hole communicating with the rod chamber, and the cylinder rear end cover is provided with a rodless chamber vent hole communicating with the rodless chamber. The piston rod is provided with an exhaust passage that communicates with the outside. The friction adjustment module includes a piston rear cover, a friction adjustment slider, a movable inclined surface component, and a radial expansion ring. The piston rear cover is fixed to the rear end of the air-float piston and has a central through hole inside. The friction adjustment slider passes through the central through hole and is slidably installed at the rear end of the air-float piston. The movable inclined surface component is fixed to the rear side of the friction adjustment slider and is positioned opposite to the piston rear cover. The radial expansion ring is placed between the piston rear cover and the movable inclined surface component. The friction adjustment slider has an air intake channel inside, and the movable inclined surface component has an internal air intake port communicating with the air intake channel. The air-floating piston has an internal piston cavity, and a baffle plate inside the piston cavity divides the piston cavity into a first cavity and a second cavity. Multiple throttling holes are formed on the side wall of the first cavity, allowing communication between the inside and outside of the air-floating piston. The second cavity is connected to the air inlet channel. A one-way valve is provided on the baffle plate, allowing gas to flow unidirectionally from the second cavity to the first cavity. An elastic reset element is provided between the friction adjusting slider and the piston rear cover. The front end of the outer circumferential surface of the air-floating piston has a first annular pressure relief groove that communicates with the exhaust channel inside the piston rod. The rodless cavity is equipped with a spiral air pipe, and the rear end cover of the cylinder is equipped with an external air inlet; the spiral air pipe is arranged in a spiral shape, and its front and rear ends are respectively connected to the internal air inlet and the external air inlet.

[0006] Furthermore, an air bearing is provided inside the cylinder front end cover, through which the piston rod passes and is radially supported.

[0007] Furthermore, the piston rear cover has a fixed inclined surface at the end of the movable inclined surface member, and the movable inclined surface member has a movable inclined surface at the end of the piston rear cover; the fixed inclined surface and the movable inclined surface together form a compression-type V-shaped annular groove, and the radial expansion ring is placed in the compression-type V-shaped annular groove.

[0008] Furthermore, the axial section of the extruded V-shaped groove is an annular wedge-shaped space formed by the fixed inclined surface and the movable inclined surface, and the fixed inclined surface and the movable inclined surface are symmetrically arranged with respect to the cylinder axis at equal angles.

[0009] Furthermore, the outermost end of the throttling orifice is provided with a pressure equalization cavity.

[0010] Furthermore, the elastic reset element is a reset spring; a receiving cavity is provided between the friction adjusting slider and the piston rear cover; the reset spring is located in the receiving cavity, with one end abutting against the inner step surface of the piston rear cover and the other end abutting against the step surface of the friction adjusting slider.

[0011] Furthermore, the rear inner circumferential surface of the air-floating piston is provided with an annular pressure relief step, and the annular pressure relief step and the mating end face of the piston rear cover form an annular air guide gap. The annular air guide gap is intermittently connected to the receiving cavity under the sliding action of the friction adjustment slider. The rear end of the outer circumferential surface of the air-floating piston is provided with a second annular pressure relief groove, and the bottom of the second annular pressure relief groove is provided with a plurality of second radial channels. The circumferential wall of the air-floating piston is provided with a first internal channel connecting the first annular pressure relief groove and the second annular pressure relief groove, and a second internal channel connecting the second radial channel and the annular air guide gap.

[0012] Furthermore, the exhaust passage within the piston rod includes a first exhaust port disposed on the outer circular surface of the front end of the piston rod, a first exhaust passage communicating with the first exhaust port, an annular exhaust chamber disposed at the connection between the piston rod and the air-float piston, and a plurality of second exhaust passages communicating with the annular exhaust chamber and the first exhaust passage; the bottom of the first annular pressure relief groove is provided with a plurality of first radial channels communicating with the annular exhaust chamber.

[0013] Furthermore, the cylinder rear end cover is provided with an air pipe storage groove. When the piston assembly moves to the cylinder rear end cover, the spiral air pipe retracts into a multi-layer disc shape and is placed inside the air pipe storage groove on the cylinder rear end cover.

[0014] Furthermore, the elastic force of the elastic reset member is less than the force corresponding to the opening pressure of the one-way valve.

[0015] Because the present invention adopts the above-described technical solution, the present invention has the following advantages: 1. The piston-independent pressure-controlled, friction-adjustable cylinder of the present invention adopts a width-adjustable V-shaped sealing structure composed of a fixed inclined surface and a movable inclined surface. The axial displacement of the friction adjustment slider changes the width of the V-shaped annular groove, causing the radial expansion ring to expand or contract radially, thereby achieving controllable switching between the elastic sealing friction pair and the gas-lubricated friction pair. The mechanical preload of the return spring ensures the default frictional contact state, and the air pressure drives the friction adjustment slider to move, causing the radial expansion ring to contract and detach from the cylinder wall, thus realizing the flexible switching of the cylinder between the two working states of friction and no friction.

[0016] 2. The piston-independent pressure-controlled and friction-adjustable cylinder of the present invention adopts an independent rear-end air supply structure. It uses a spiral-coiled air pipe to supply air directly to the piston assembly from the rear end cover of the cylinder. The air supply path is completely separated from the piston rod and the front-end actuator, so as not to interfere with the reciprocating motion of the piston rod and the installation of the front-end actuator. Moreover, the spiral air pipe extends and retracts synchronously with the piston assembly, effectively reducing the impact on the effective stroke of the cylinder.

[0017] 3. The piston-independent pressure-controlled and friction-adjustable cylinder of the present invention integrates a one-way valve and a throttle orifice structure inside the air-float piston. The timing control is achieved by using the opening pressure threshold of the one-way valve, so that the same downstream air supply sequentially completes the driving of the friction adjustment module and the establishment of the air-float support film. The structure is highly integrated, the air path logic is clear, and the control is simple. Attached Figure Description

[0018] Figure 1 This is a top-view schematic diagram of the overall structure of the present invention.

[0019] Figure 2 This is a top-side view of the overall structure of the present invention.

[0020] Figure 3 This is a schematic diagram of the structure of the present invention after vertical cross-section.

[0021] Figure 4 This is a schematic diagram of the structure of the present invention after removing the front cover of the cylinder, the cylinder barrel, and the rear cover of the cylinder.

[0022] Figure 5 This is a schematic cross-sectional view of the piston rod at sections AA and BB of the present invention.

[0023] Figure 6 This is a schematic diagram of the friction adjustment module of the present invention after being horizontally cut open.

[0024] Figure 7 This is a schematic diagram of the front side of the structure of the air-floating piston of the present invention.

[0025] Figure 8 This is a schematic diagram of the rear side of the structure of the air-floating piston of the present invention.

[0026] Figure 9 This is a schematic diagram of the structure of the air-floating piston of the present invention after being vertically cut open.

[0027] Figure 10 This is a schematic diagram of the structure of the air-float piston of the present invention after being horizontally cut open.

[0028] Figure 11 This is a schematic diagram of the friction adjustment module of the present invention in a frictionless state.

[0029] Figure 12 This is a schematic diagram of the friction adjustment module of the present invention under friction conditions.

[0030] Icon labels: 1-Piston rod; 101-First exhaust port; 102-First exhaust passage; 103-Annular exhaust chamber; 104-Second exhaust passage; 2-Air-float piston; 201-First annular pressure relief groove; 202-Second annular pressure relief groove; 203-Piston cavity; 204-Pressure equalization chamber; 205-Throttle orifice; 206-First radial passage; 207-Second radial passage; 208-First internal passage; 209-Second internal passage; 210-Annular pressure relief step; 211-Annular positioning step; 212-Annular air guide gap; 213-Baffle; 3-Piston rear cover ; 301-Fixed inclined plane; 302-Central through hole; 303-Receiving cavity; 4-Friction adjustment slider; 401-Inlet channel; 5-Modible inclined plane; 501-Modible inclined plane; 502-Inner air inlet; 6-Radial expansion ring; 7-Reset spring; 8-Spiral air pipe; 9-Air bearing; 10-Cylinder front end cover; 1001-Rod chamber vent; 11-Cylinder barrel; 12-Cylinder rear end cover; 1201-Rodless chamber vent; 13-One-way valve; 14-Baffle; 15-First cavity; 16-Outer air inlet; 17-Air pipe storage groove; 18-Second cavity. Detailed Implementation

[0031] 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.

[0032] 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:

[0033] This embodiment provides a piston-independent pressure-controlled, friction-adjustable cylinder, comprising two parts: an air-float frictionless cylinder and a friction adjustment module. For example... Figure 1 and Figure 2 As shown, the air-float frictionless cylinder includes a cylinder front cover 10, a cylinder barrel 11, and a cylinder rear cover 12 connected in sequence, and a piston rod 1 is slidably installed inside, providing contactless motion support through the principle of gas lubrication. The friction adjustment module introduces controllable friction damping when needed through a mechanical extrusion mechanism.

[0034] like Figure 3 As shown, an air-floating piston 2 is fitted inside the cylinder 11. The outer diameter of the air-floating piston 2 is smaller than the inner diameter of the cylinder 11. The piston rod 1 is fixedly connected to the front end of the air-floating piston 2 (e.g., by a threaded connection). The air-floating piston 2 divides the inside of the cylinder 11 into a rod chamber and a rodless chamber. The cylinder front end cover 10 has a rod chamber vent hole 1001 communicating with the rod chamber, and the cylinder rear end cover 12 has a rodless chamber vent hole 1201 communicating with the rodless chamber, for the purpose of realizing the normal reciprocating motion of the cylinder. An air bearing 9 is installed inside the cylinder front end cover 10, through which the piston rod 1 passes and is radially supported.

[0035] like Figures 4-5 As shown, a first exhaust port 101 is provided on the outer circular surface of the front end of the piston rod 1, and a first exhaust channel 102 communicating with the first exhaust port 101 is provided inside the piston rod 1; an annular exhaust chamber 103 is provided at the connection between the piston rod 1 and the air-float piston 2 (e.g., Figure 5 At the location of the BB section shown, a number of second exhaust channels 104 are provided between the annular exhaust chamber 103 and the first exhaust channel 102.

[0036] like Figures 3-4 and Figure 6As shown, the friction adjustment module includes a piston rear cover 3, a friction adjustment slider 4, a movable inclined surface 5, and a radial expansion ring 6. The piston rear cover 3 is fixed to the rear end of the air-floating piston 2, and has a central through hole 302 inside. The friction adjustment slider 4 passes through the central through hole 302 of the piston rear cover 3 and is slidably installed at the rear end of the air-floating piston 2. The movable inclined surface 5 is fixed to the rear side of the friction adjustment slider 4 and is arranged opposite to the piston rear cover 3. The piston rear cover 3 has a fixed inclined surface 301 at the end relative to the movable inclined surface 5, and the movable inclined surface 5 has a movable inclined surface 501 at the end relative to the piston rear cover 3. The fixed inclined surface 301 and the movable inclined surface 501... 01 together form a compression-type V-shaped annular groove, with the radial expansion ring 6 placed inside the compression-type V-shaped annular groove; the friction adjusting slider 4 has an air inlet channel 401 inside, and the movable inclined surface 5 has an inner air inlet 502 that communicates with the air inlet channel 401 inside; a receiving cavity 303 is provided between the friction adjusting slider 4 and the piston rear cover 3, and a return spring 7 is provided inside the receiving cavity 303. The return spring 7 is a compression spring, which is in a compressed state by default. One end of the spring abuts against the inner step surface of the piston rear cover 3, and the other end abuts against the step surface of the friction adjusting slider 4, which is used to provide a return preload force to move the friction adjusting slider 4 forward, so that the compression-type V-shaped annular groove tends to narrow.

[0037] like Figure 11 and Figure 12 As shown, the axial section of the extruded V-shaped groove is an annular wedge-shaped space formed by the fixed inclined surface 301 and the movable inclined surface 501. The fixed inclined surface 301 and the movable inclined surface 501 are symmetrically arranged with respect to the axis of the cylinder 11 at equal angles.

[0038] like Figures 7-10 As shown, the air-floating piston 2 has a piston cavity 203 inside, and a baffle 14 inside the piston cavity 203. The baffle 14 divides the piston cavity 203 into a first cavity 15 and a second cavity 18. Multiple throttling holes 205 are opened on the side wall of the first cavity 15 to connect the inside and outside of the air-floating piston 2. The outermost end of the throttling hole 205 is provided with a pressure equalization chamber 204. The second cavity 18 is connected to the air intake channel 401. A one-way valve 13 is provided on the baffle 14. The one-way valve 13 allows gas to flow unidirectionally from the second cavity 18 to the first cavity 15 and prevents reverse flow.

[0039] It is worth noting that the spring force of the return spring 7 is less than the force corresponding to the opening pressure of the one-way valve 13.

[0040] The front end of the outer circumferential surface of the air-float piston 2 is provided with a first annular pressure relief groove 201 that surrounds the circumference. The bottom of the first annular pressure relief groove 201 is provided with a plurality of first radial channels 206 that communicate with the annular exhaust chamber 103.

[0041] An annular pressure relief step 210 is provided on the inner circumferential surface of the rear end of the air-floating piston 2. The annular pressure relief step 210 and the mating end face of the piston rear cover 3 form an annular air guide gap 212. The annular air guide gap 212 is intermittently connected to the receiving cavity 303 under the sliding action of the friction adjustment slider 4. A second annular pressure relief groove 202 is provided on the rear end of the outer circumferential surface of the air-floating piston 2, and a plurality of second radial channels 207 are provided at the bottom of the second annular pressure relief groove 202. A first internal channel 208 is provided in the circumferential wall of the air-floating piston 2, which connects the first annular pressure relief groove 201 and the second annular pressure relief groove 202, and a second internal channel 209 connects the second radial channel 207 and the annular air guide gap 212. The annular air guide gap 212 connects the second internal channel 209 and the receiving cavity 303 where the return spring 7 is located, so as to achieve air pressure balance in the receiving cavity 303 during the extension and contraction of the return spring 7.

[0042] The friction adjusting slider 4 and the central through hole 302 of the piston rear cover 3 are clearance fit. An annular sealing groove is provided on the front stepped surface of the friction adjusting slider 4, and a sealing ring is provided in the annular sealing groove to achieve dynamic sealing between the friction adjusting slider 4 and the air-floating piston 2.

[0043] The friction adjustment slider 4 and the movable inclined surface 5 are connected by threads. The right end face of the friction adjustment slider 4 is provided with a sealing groove, and a sealing ring is provided in the sealing groove to seal the contact surface between the friction adjustment slider 4 and the movable inclined surface 5.

[0044] In one specific embodiment of this invention, an annular positioning step 211 is provided on the inner wall of the air-floating piston 2; a baffle 14 is threadedly connected to the inside of the air-floating piston 2, and the mounting end face of the baffle 14 abuts against the annular positioning step 211 to axially position the baffle 14. The other end face of the baffle 14 corresponds to the front end face of the friction adjusting slider 4 to form a mechanical limit for the forward movement of the friction adjusting slider 4.

[0045] As a specific implementation of this embodiment, a partition 213 is fixedly provided at the front end of the piston cavity 203. The space between the partition 213 and the baffle 14 is the first cavity 15, and the space between the baffle 14 and the friction adjustment slider 4 is the second cavity 18. A coaxial air hole is provided at the center of the baffle 14. The one-way valve 13 is sealed to the coaxial air hole at the center of the baffle 14 by a thread to allow gas to flow unidirectionally from the second cavity 18 to the first cavity 15.

[0046] In one specific implementation of this embodiment, the throttling orifice 205 is axially divided into 3 to 5 rows on the outer wall of the air-floating piston 2, with 4 to 8 orifices evenly distributed circumferentially in each row. The number of the first internal channel 208 and the second internal channel 209 are each 4 to 8, and they are evenly distributed circumferentially within the circumferential wall of the air-floating piston 2.

[0047] like Figure 3 and Figure 4 As shown, a spiral air tube 8 is provided in the rodless chamber, and an external air inlet 16 is provided on the cylinder rear end cover 12; the spiral air tube 8 is spirally coiled, and its front and rear ends are connected to the internal air inlet 502 and the external air inlet 16, respectively; an air tube storage groove 17 is provided in the cylinder rear end cover 12. When the piston assembly moves to the cylinder rear end cover 12, the spiral air tube 8 retracts into a multi-layer disc shape and is placed inside the air tube storage groove 17 on the cylinder rear end cover 12.

[0048] The working principle of this embodiment is as follows: I. Principle of Cylinder Reciprocating Motion In this embodiment, the cylinder achieves the reciprocating motion of the piston rod 1 through the intake and exhaust coordination of the rod chamber vent 1001 and the rodless chamber vent 1201. When compressed air enters the rodless chamber through the rodless chamber vent 1201, and at the same time the rod chamber exhausts through the rod chamber vent 1001, the air-floating piston 2 drives the piston rod 1 to extend forward; when compressed air enters the rod chamber through the rod chamber vent 1001, and at the same time the rodless chamber exhausts through the rodless chamber vent 1201, the air-floating piston 2 drives the piston rod 1 to retract backward.

[0049] During the reciprocating motion of piston rod 1, spiral air tube 8 extends and retracts axially along with piston assembly, utilizing its flexible spiral structure to adapt to piston movement without interfering with the movement of piston rod 1.

[0050] 2. The air-float piston 2 is in a friction state (normal friction cylinder state). like Figure 12 As shown, when compressed air is not introduced into the external air inlet 16, the friction adjustment module is in a frictional state. At this time, the return spring 7 is in a pre-compressed state and releases its elastic force, abutting against the stepped surface of the friction adjustment slider 4, driving the friction adjustment slider 4 to move forward. As the friction adjustment slider 4 moves forward until its front end face abuts against the end face of the baffle 14 to achieve mechanical limitation, the movable inclined surface 5 continuously approaches the piston rear cover 3, causing the axial width of the extrusion V-shaped ring groove to decrease, forcing the radial expansion ring 6 to deform radially outward under the extrusion of the wedge-shaped space, thereby making close contact with the inner wall of the cylinder 11 and forming friction. At this time, the radial expansion ring 6 contacts the inner wall of the cylinder 11, which can provide the necessary damping and realize high-precision motion servo control.

[0051] III. Frictionless state of air-float piston 2 (full air-float state) like Figure 11As shown, when the air-floating piston 2 needs to be in a fully air-floating state, air is supplied to the friction adjustment module through the external air inlet 16. Compressed air enters the second chamber 18 sequentially through the spiral air pipe 8, the internal air inlet 502 on the right side of the movable inclined plate 5, and the air inlet channel 401. As the pressure in the second chamber 18 increases, the air pressure acting on the front end face of the friction adjustment slider 4 gradually increases. When the air pressure is sufficient to overcome the elastic force of the return spring 7, it drives the friction adjustment slider 4 to move backward until the front stepped surface of the friction adjustment slider 4 abuts against the stepped surface of the piston rear cover 3 to achieve mechanical limitation. During this process, the movable inclined plate 5 moves backward with the friction adjustment slider 4 and moves away from the piston rear cover 3. The axial width of the extrusion V-shaped ring groove increases, and the radial expansion ring 6 loses its extrusion component and undergoes radial contraction under its own elasticity, thereby disengaging from the contact with the inner wall of the cylinder 11.

[0052] When the friction adjusting slider 4 moves backward to the mechanical limit, the pressure in the second chamber 18 continues to rise. When the pressure reaches the opening pressure of the one-way valve 13, the high-pressure gas in the second chamber 18 enters the first chamber 15 through the one-way valve 13 on the baffle 14. Subsequently, it is injected into the cylinder gap through the throttling hole 205 on the wall of the air-floating piston 2, forming a high-pressure bearing gas film, which makes the air-floating piston 2 completely suspended. At this time, the radial expansion ring 6 has no contact with the inner wall of the cylinder 11, and the air-floating piston 2 and the cylinder 11 achieve zero contact through the high-pressure gas film. The cylinder is in a fully air-floating, frictionless state, and the frictional resistance is close to zero, which can achieve high-precision force servo control.

[0053] After the high-pressure gas film is formed, the gas leaking from both ends of the gas film enters the first annular pressure relief groove 201 and the second annular pressure relief groove 202, respectively. The gas entering the first annular pressure relief groove 201 flows into the annular exhaust chamber 103 through the first radial channel 206, and then is discharged into the atmosphere from the first exhaust port 101 through the first exhaust channel 102. The gas entering the second annular pressure relief groove 202 enters the second radial channel 207. Part of the gas flows into the second internal channel 209 and enters the receiving cavity 303 through the annular air guide gap 212 to achieve air pressure balance during the extension and contraction of the return spring 7. The other part of the gas flows into the first annular pressure relief groove 201 through the first internal channel 208, merges with the gas leaking from the front end, and is discharged into the atmosphere from the first exhaust port 101 through the first radial channel 206, the annular exhaust chamber 103, and the first exhaust channel 102.

[0054] When the air supply to the rear end cover is stopped, the air pressure in the second chamber 18 drops rapidly. The friction adjustment slider 4 automatically resets under the preload of the return spring 7, and re-presses the radial expansion ring 6 to expand it and make it contact the cylinder 11. The cylinder returns to the normal friction state.

[0055] The core of this invention is that the fixed inclined surface 301 of the piston rear cover 3 and the movable inclined surface 501 of the movable inclined surface component 5 together form an adjustable V-shaped sealing structure, in which the radial expansion ring 6 is placed; under the alternating drive of the return spring 7 and the rear air pressure, the change in the width of the V-shaped ring groove causes the radial expansion ring 6 to contact or separate from the inner wall of the cylinder 11, and with the timing control of the one-way valve 13, the friction adjustment and the air float supply are connected sequentially, thereby realizing the controllable switching between the elastic sealing friction pair and the gas lubrication friction pair.

Claims

1. A cylinder with independent piston pressure control and adjustable friction, characterized in that, Includes air-float frictionless cylinder and friction adjustment module; The air-float frictionless cylinder includes a cylinder front end cover (10), a cylinder barrel (11), and a cylinder rear end cover (12) connected in sequence, and a piston rod (1) is slidably installed inside. An air-float piston (2) is fixedly installed on the piston rod (1) and slidably installed inside the cylinder barrel (11). The outer diameter of the air-float piston (2) is smaller than the inner diameter of the cylinder barrel (11). The air-float piston (2) divides the inside of the cylinder barrel (11) into a rod chamber and a rodless chamber. The cylinder front end cover (10) is provided with a rod chamber vent hole (1001) communicating with the rod chamber, and the cylinder rear end cover (12) is provided with a rodless chamber vent hole (1201) communicating with the rodless chamber. The piston rod (1) is provided with an exhaust channel that communicates with the outside. The friction adjustment module includes a piston rear cover (3), a friction adjustment slider (4), a movable inclined surface (5), and a radial expansion ring (6). The piston rear cover (3) is fixed to the rear end of the air-floating piston (2) and has a central through hole (302) inside. The friction adjustment slider (4) passes through the central through hole (302) and is slidably installed at the rear end of the air-floating piston (2). The movable inclined surface (5) is fixed to the rear side of the friction adjustment slider (4) and is arranged opposite to the piston rear cover (3). The radial expansion ring (6) is placed between the piston rear cover (3) and the movable inclined surface (5). The friction adjustment slider (4) has an air intake channel (401) inside, and the movable inclined surface (5) has an internal air intake port (502) communicating with the air intake channel (401). The air-floating piston (2) has a piston cavity (203) inside, and a baffle (14) inside the piston cavity (203) divides the piston cavity (203) into a first cavity (15) and a second cavity (18). The side wall of the first cavity (15) is provided with a plurality of throttling holes (205) that allow the air-floating piston (2) to communicate with the inside and outside. The second cavity (18) is connected to the air intake channel (401). The baffle (14) is provided with a one-way valve (13), which allows gas to flow unidirectionally from the second cavity (18) to the first cavity (15). An elastic reset member is provided between the friction adjusting slider (4) and the piston rear cover (3). The front end of the outer circumferential surface of the air-floating piston (2) is provided with a first annular pressure relief groove (201) that communicates with the exhaust channel inside the piston rod (1). The rodless cavity is provided with a spiral air pipe (8), and the cylinder rear end cover (12) is provided with an external air inlet (16); the spiral air pipe (8) is spirally coiled, and its front and rear ends are respectively connected to the internal air inlet (502) and the external air inlet (16).

2. The piston-independent pressure-controlled, friction-adjustable cylinder according to claim 1, characterized in that, An air bearing (9) is provided inside the cylinder front cover (10), through which the piston rod (1) passes and is radially supported.

3. The piston-independent pressure-controlled, friction-adjustable cylinder according to claim 1, characterized in that, The piston rear cover (3) has a fixed inclined surface (301) at the end of the movable inclined surface (5) and a movable inclined surface (501) at the end of the piston rear cover (3); the fixed inclined surface (301) and the movable inclined surface (501) together form a compression-type V-shaped ring groove, and the radial expansion ring (6) is placed in the compression-type V-shaped ring groove.

4. The piston-independent pressure-controlled, friction-adjustable cylinder according to claim 3, characterized in that, The axial section of the extruded V-shaped groove is an annular wedge-shaped space formed by the fixed inclined surface (301) and the movable inclined surface (501) relative to each other. The fixed inclined surface (301) and the movable inclined surface (501) are symmetrically arranged with respect to the axis of the cylinder (11).

5. The piston-independent pressure-controlled, friction-adjustable cylinder according to claim 1, characterized in that, The outermost end of the throttling orifice (205) is provided with a pressure equalization chamber (204).

6. The piston-independent pressure-controlled, friction-adjustable cylinder according to claim 1, characterized in that, The elastic reset component is a reset spring (7); a receiving cavity (303) is provided between the friction adjustment slider (4) and the piston rear cover (3); the reset spring (7) is located in the receiving cavity (303), with one end abutting against the inner step surface of the piston rear cover (3) and the other end abutting against the step surface of the friction adjustment slider (4).

7. The piston-independent pressure-controlled, friction-adjustable cylinder according to claim 6, characterized in that, The rear end inner circumferential surface of the air-floating piston (2) is provided with an annular pressure relief step (210), and the annular pressure relief step (210) and the mating end face of the piston rear cover (3) form an annular air guide gap (212). The annular air guide gap (212) is intermittently connected to the receiving cavity (303) under the sliding action of the friction adjustment slider (4). The rear end of the outer circumferential surface of the air-floating piston (2) is provided with a second annular pressure relief groove (202), and the bottom of the second annular pressure relief groove (202) is provided with a plurality of second radial channels (207). The circumferential wall of the air-floating piston (2) is provided with a first internal channel (208) connecting the first annular pressure relief groove (201) and the second annular pressure relief groove (202), and a second internal channel (209) connecting the second radial channel (207) and the annular air guide gap (212).

8. The piston-independent pressure-controlled, friction-adjustable cylinder according to claim 1, characterized in that, The exhaust passage inside the piston rod (1) includes a first exhaust port (101) disposed on the outer circular surface of the front end of the piston rod (1), a first exhaust passage (102) communicating with the first exhaust port (101), an annular exhaust chamber (103) disposed at the connection between the piston rod (1) and the air-float piston (2), and a plurality of second exhaust passages (104) communicating with the annular exhaust chamber (103) and the first exhaust passage (102); the bottom of the first annular pressure relief groove (201) is provided with a plurality of first radial passages (206) communicating with the annular exhaust chamber (103).

9. The piston-independent pressure-controlled, friction-adjustable cylinder according to claim 1, characterized in that, The cylinder rear end cover (12) is provided with an air pipe storage groove (17). When the piston assembly moves to the cylinder rear end cover (12), the spiral air pipe (8) shrinks into a multi-layer disc shape and is placed inside the air pipe storage groove (17) on the cylinder rear end cover (12).

10. The piston-independent pressure-controlled, friction-adjustable cylinder according to claim 1, characterized in that, The elastic force of the elastic reset member is less than the force corresponding to the opening pressure of the one-way valve (13).

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