Fluid cylinder

Abstract

The present application relates to a kind of fluid cylinder, the fluid cylinder includes: cylinder assembly and pilot valve, the cylinder assembly includes cylinder body, piston rod and transmission component, the piston rod extends from one end of the cylinder body, the transmission component extends from the other end of the cylinder body, the piston rod is connected with the transmission component, the piston rod is movable along the axial direction of the cylinder body, to drive the transmission component relative to the cylinder body rotation, the pilot valve includes pilot valve body, valve seat and pilot valve core, the pilot valve core and the valve seat are all arranged in the pilot valve body and along the axial direction of the pilot valve body translation, the valve seat is rotationally engaged with the pilot valve body, the transmission component is threadedly engaged with the valve seat, the transmission component can drive the valve seat translation, to make the valve seat push the pilot valve core translation.The fluid cylinder of the present application can slow down the wear of the pilot valve core, reduce the failure rate of the pilot valve, and prolong the maintenance cycle.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automation equipment, in particular, to a fluid cylinder. BACKGROUND

[0002] The two most important execution elements in hydraulic system are hydraulic cylinder and hydraulic motor, and the hydraulic cylinder is more widely used than the hydraulic motor. The traditional hydraulic cylinder is only used as a simple power execution element, and its movement is controlled by other fluid control elements. In order to make the hydraulic cylinder meet various functional requirements, various fluid control elements are invented, such as directional valve, throttle valve, speed regulating valve, proportional valve, servo valve and dozens of specifications and hundreds of products to meet the different control requirements of the hydraulic cylinder, so that the hydraulic technology becomes very complex.

[0003] In the related art, there are mainly two ways to realize the position control of the hydraulic cylinder. One is the valve control mode of electric signal feedback, which mainly generates an electric signal by detecting the position of the piston rod to feedback control the hydraulic valve. The other is the mechanical feedback control mode, which integrates the hydraulic valve and the hydraulic cylinder and has a mechanical feedback device.

[0004] For example, a digital cylinder composed of a stepper motor, a double-stage screw pair, a three-position four-way valve and a hydraulic cylinder. The stepper motor and the piston rod of the hydraulic cylinder pass through the double-stage screw pair to control the working position of the three-position four-way valve, so as to realize the position control of the piston rod. However, during the operation of the digital cylinder, the spool of the three-position four-way valve will move horizontally and rotate, so that the sealing element on the spool is worn out quickly and has a short service life. SUMMARY

[0005] The present application aims to at least solve one of the technical problems in the related art to some extent.

[0006] To this end, the embodiment of the present application provides a fluid cylinder which can slow down the wear of the pilot spool, reduce the failure rate of the pilot valve and prolong the maintenance cycle.

[0007] The fluid cylinder of the embodiment of the present application comprises: a cylinder assembly, the cylinder assembly comprising a cylinder body, a piston rod and a transmission part, the piston rod extending from one end of the cylinder body, the transmission part extending from the other end of the cylinder body, the piston rod being connected with the transmission part, the piston rod being movable along the axial direction of the cylinder body to drive the transmission part to rotate relative to the cylinder body; a pilot valve, the pilot valve comprising a pilot valve body, a valve seat and a pilot spool, the pilot spool and the valve seat being arranged in the pilot valve body and moving horizontally along the axial direction of the pilot valve body, the valve seat being rotationally connected with the pilot valve body, the transmission part being threadedly connected with the valve seat, the transmission part being capable of driving the valve seat to move horizontally so that the valve seat drives the pilot spool to move horizontally.

[0008] The fluid cylinder according to the embodiments of the present application can drive the transmission component to rotate relative to the cylinder body due to the axial movement of the piston rod, the rotation of the transmission component can drive the valve seat to move horizontally, and the valve core in the pilot valve body is further driven to move horizontally, the transmission component of the fluid cylinder according to the embodiments of the present application can only drive the pilot valve core to move horizontally without rotation, thereby reducing the problem of wear of the pilot valve core, reducing the failure rate of the fluid cylinder, and prolonging the maintenance cycle of the fluid cylinder.

[0009] In some embodiments, the fluid cylinder further comprises a proportional solenoid arranged at one end of the pilot valve core away from the valve seat, and the proportional solenoid is used to drive the pilot valve core to move horizontally towards the valve seat.

[0010] In some embodiments, the pilot valve further comprises a first elastic member arranged in the pilot valve body and arranged between the valve seat and the pilot valve core, one end of the first elastic member abuts against the valve seat, and the other end of the first elastic member abuts against the pilot valve core.

[0011] In some embodiments, the first elastic member is a coil spring, and the pilot valve further comprises a thrust bearing arranged at one end of the valve seat adjacent to the pilot valve core, one end of the thrust bearing abuts against the valve seat, and the other end of the thrust bearing is connected to the first elastic member.

[0012] In some embodiments, the pilot valve body is provided with a communication guide channel and a pilot valve cavity, the pilot valve core is arranged in the pilot valve cavity, the guide channel comprises a first section and a second section coaxially connected, the second section is arranged between the first section and the pilot valve cavity, a stepped surface is arranged between the second section and the first section, at least part of the valve seat is arranged to be rotationally stopped in the first section and is axially movable along the first section, the valve seat can abut against the stepped surface to axially limit the valve seat, and the first elastic member is arranged in the second section.

[0013] In some embodiments, the transmission component comprises a lead screw and a nut, one end of the piston rod towards the pilot valve is provided with a mounting cavity, the nut is arranged at the opening of the mounting cavity, one end of the lead screw is arranged in the mounting cavity and threadedly cooperates with the nut, the other end of the lead screw is pivotally connected with the cylinder body, the other end of the lead screw extends out of the cylinder body and threadedly cooperates with the valve seat.

[0014] In some embodiments, the fluid cylinder further comprises a laser displacement sensor arranged on the cylinder body, and the laser displacement sensor is used to detect the extension position of the piston rod.

[0015] In some embodiments, the fluid cylinder further comprises a main valve, the main valve comprising a main valve core and a main valve body, the main valve core being provided with a main valve cavity, the main valve core being arranged in the main valve cavity and being movable along the axial direction of the main valve cavity, the pilot valve body being provided with a pilot valve cavity, the pilot valve cavity being in communication with the main valve cavity, the main valve cavity being in communication with a first flow channel and a second flow channel, the piston rod surrounding the cylinder body to form a first chamber and a second chamber which are independent of each other, the first flow channel being in communication with the first chamber, and the second flow channel being in communication with the second chamber.

[0016] In some embodiments, the main valve further comprises two second elastic members, the two second elastic members being arranged on both sides of the axial direction of the main valve core and being arranged in the main valve body, respectively, and the second elastic members pressing the main valve core in the direction of the main valve core.

[0017] In some embodiments, the pilot valve further comprises a first sealing member arranged between the pilot valve core and the pilot valve body, and / or the main valve further comprises a second sealing member arranged between the main valve core and the main valve body. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a schematic view of a fluid cylinder according to an embodiment of the present application.

[0019] Figure 2 is a partial sectional view of a fluid cylinder according to an embodiment of the present application.

[0020] Figure 3 is a partial sectional view of a pilot valve and cylinder assembly of a fluid cylinder according to an embodiment of the present application.

[0021] REFERENCE NUMERALS:

[0022] 1, cylinder assembly; 11, cylinder body; 111, first chamber; 112, second chamber; 12, piston rod; 121, mounting cavity; 13, transmission component; 131, screw rod; 132, nut; 14, first bearing;

[0023] 2, pilot valve; 21, pilot valve body; 211, pilot valve cavity; 212, guide passage; 2121, first section; 2122, second section; 22, valve seat; 23, pilot valve core; 24, first elastic member; 25, thrust bearing;

[0024] 3, main valve; 31, main valve core; 32, main valve body; 321, left valve cover; 322, right valve cover; 33, second elastic member; 34, first flow channel; 35, second flow channel;

[0025] 4, proportional solenoid;

[0026] 5, laser displacement sensor. DETAILED DESCRIPTION

[0027] Embodiments of the present application are described in detail below with reference to the attached drawing figures, wherein the embodiments described are examples of the present application and are not intended to limit the present application.

[0028] Reference will now be made in detail embodiments of the present application, examples of which are illustrated in the accompanying drawings. The embodiments described below are exemplary and are not intended to limit the present application. Figures 1 to 3 A fluid cylinder according to an embodiment of the present application is described below.

[0029] As shown in Figure 1 and Figure 2 , a fluid cylinder according to an embodiment of the present application comprises a cylinder assembly 1 and a pilot valve 2. The cylinder assembly 1 comprises a cylinder body 11, a piston rod 12 and a transmission component 13, the piston rod 12 extends from one end of the cylinder body 11 (e.g. the left end of the cylinder body 11 as shown in Figure 1 ), the transmission component 13 extends from the other end of the cylinder body 11 (e.g. the right end of the cylinder body 11 as shown in Figure 1 ), the piston rod 12 is connected to the transmission component 13, and the piston rod 12 is movable along the axial direction of the cylinder body 11 to drive the transmission component 13 to rotate relative to the cylinder body 11.

[0030] The pilot valve 2 comprises a pilot valve body 21, a valve seat 22 and a pilot valve spool 23, the pilot valve spool 23 and the valve seat 22 are both arranged in the pilot valve body 21 and are movable along the axial direction of the pilot valve body 21 (e.g. the left-right direction as shown in Figure 1 ), the valve seat 22 is rotationally fixed to the pilot valve body 21, the transmission component 13 is threadedly connected to the valve seat 22, and the transmission component 13 can drive the valve seat 22 to move to push the pilot valve spool 23 to move.

[0031] According to an embodiment of the present application, the piston rod 12 is movable along the axial direction of the cylinder body 11 to drive the transmission component 13 to rotate relative to the cylinder body 11, the transmission component 13 is movable to drive the valve seat 22 to move to push the pilot valve spool 23 to move in the pilot valve body 21, and the transmission component 13 of the fluid cylinder according to the embodiment of the present application can only move the pilot valve body 21 to move but not to rotate, thereby reducing the wear of the pilot valve body 21, reducing the failure rate of the fluid cylinder and prolonging the maintenance cycle of the fluid cylinder.

[0032] Optionally, as shown in Figures 1 to 3 , the fluid cylinder further comprises a proportional solenoid 4, the proportional solenoid 4 is arranged at the end of the pilot valve spool 23 away from the valve seat 22, and the proportional solenoid 4 is used to drive the pilot valve spool 23 to move towards the valve seat 22. It can be understood that, as Figure 1As shown, the transmission component 13 can drive the spool to move right, and the proportional electromagnet 4 can drive the pilot valve body 21 to move left. The fluid cylinder of the embodiment of the present application has simple structure, small power, less heat, and low cost compared to the stepper motor structure. And the double feedback control composed of the mechanical feedback of the transmission component 13 and the electrical signal feedback of the proportional electromagnet 4 can improve the control accuracy of the fluid cylinder.

[0033] In some embodiments, as shown in Figure 2 and Figure 3 The pilot valve 2 further comprises a first elastic member 24, which is located in the pilot valve body 21 and arranged between the valve seat 22 and the pilot valve spool 23. One end of the first elastic member 24 abuts against the valve seat 22, and the other end of the first elastic member 24 abuts against the pilot valve spool 23. For example, the first elastic member 24 is a metal spring, a gas spring or other type of spring, and the specific structure of the first elastic member 24 is not limited in the present application. It can be understood that, since the first elastic member 24 is arranged between the valve seat 22 and the pilot valve spool 23, the hard contact between the valve seat 22 and the pilot valve spool 23 can be avoided, so that the force transmission effect of the valve seat 22 and the pilot valve spool 23 is better.

[0034] Optionally, as shown in Figure 2 and Figure 3 The first elastic member 24 is a coil spring, and the pilot valve 2 further comprises a thrust bearing 25 arranged at one end of the valve seat 22 adjacent to the pilot valve spool 23. One end of the thrust bearing 25 abuts against the valve seat 22, and the other end of the thrust bearing 25 is connected to the first elastic member 24. It can be understood that the left end of the thrust bearing 25 abuts against the valve seat 22, and the right end of the thrust bearing 25 abuts against the first elastic member 24. It can be understood that when the first elastic member 24 is compressed or elongated, the first elastic member 24 can rotate. Since the thrust bearing 25 can rotate freely, the force value transmitted by the first elastic member 24 can be more accurate, and the control accuracy of the fluid cylinder is further improved.

[0035] Specifically, as shown in Figure 3As shown, the pilot valve body 21 has a connecting guide channel 212 and a pilot valve cavity 211. The pilot valve core 23 is located in the pilot valve cavity 211. The guide channel 212 includes a first section 2121 and a second section 2122 coaxially connected. The second section 2122 is located between the first section 2121 and the pilot valve cavity 211. A stepped surface is provided between the second section 2122 and the first section 2121. At least part of the valve seat 22 is anti-rotatingly disposed in the first section 2121 and is movable along the axial direction of the first section 2121. The valve seat 22 can abut against the stepped surface to axially limit the valve seat 22. The first elastic element 24 is located in the second section 2122. It can be understood that the first section 2121, the second section 2122, and the pilot valve cavity 211 are all located on the same axis. When the valve seat 22 moves to the right to its limit position, the valve seat 22 can abut against the stepped surface, thereby limiting the valve seat 22 and improving the accuracy of the pilot valve core 23 movement.

[0036] In some embodiments, such as Figure 1 and Figure 2 As shown, the transmission component 13 includes a lead screw 131 and a nut 132. The piston rod 12 has a mounting cavity 121 at one end facing the pilot valve 2. The nut 132 is located at the opening of the mounting cavity 121. One end of the lead screw 131 passes through the mounting cavity 121 and is threadedly engaged with the nut 132. The other end of the lead screw 131 is pivotally connected to the cylinder body 11 and extends out of the cylinder body 11, threadedly engaging with the valve seat 22. It is understood that the nut 132 can be fixed to the piston rod 12 by bolts, and the nut 132 can move as the piston rod 12 moves. Since the lead screw 131 is supported by the cylinder body 11 through a first bearing 14, the movement of the nut 132 can drive the lead screw 131 to rotate. The right end of the lead screw 131 is threadedly engaged in the valve seat 22. When the lead screw 131 rotates, the valve seat 22 can move forward or backward along the axial direction of the first segment 2121. By configuring the transmission component 13 as described above, the fluid cylinder of the embodiment of the present invention can simplify the transmission structure of the fluid cylinder and facilitate installation and maintenance.

[0037] Optionally, such as Figure 1 As shown, the fluid cylinder also includes a laser displacement sensor 5, which is mounted on the cylinder body 11. The laser displacement sensor 5 is used to detect the extended position of the piston rod 12. It can be understood that the laser displacement sensor 5 can detect the position of the piston rod 12 and its end, thereby determining the extended position of the piston rod 12. During the adjustment of the piston rod 12's position, the current value of the proportional electromagnet 4 does not abruptly change to the target value, but rather changes continuously at a certain slope. When the laser displacement sensor 5 detects that the piston rod 12 has reached the target position, the current value stops changing.

[0038] In some embodiments, such as Figure 1 andFigure 2 As shown, the fluid cylinder also includes a main valve 3, which includes a main valve core 31 and a main valve body 32. The main valve core 31 has a main valve chamber and is located within the main valve chamber and is movable along the axial direction of the main valve chamber. The pilot valve chamber 211 communicates with the main valve chamber, and the main valve chamber is connected by a first flow channel 34 and a second flow channel 35. The piston rod 12 encloses the cylinder body 11 into two independent chambers, a first chamber 111 and a second chamber 112. Figure 1 As shown, the first chamber 111 and the second chamber 112 are the right side chamber and left side wall of the cylinder body 11. The first flow channel 34 communicates with the first chamber 111, and the second flow channel 35 communicates with the second chamber 112. It can be understood that the main valve core 31 can move left and right within the main valve chamber to allow hydraulic oil to flow into either the first chamber 111 or the second chamber 112, thereby driving the piston rod 12 to extend and retract.

[0039] Optionally, such as Figure 1 and Figure 2 As shown, the main valve 3 also includes two second elastic elements 33. Both second elastic elements 33 are disposed within the main valve body 32 and are respectively arranged on both sides of the main valve core 31 along its axial direction. The second elastic elements 33 press against the main valve core 31 in the direction towards it. By providing two second elastic elements 33 within the main valve 3, the fluid cylinder of this embodiment of the invention can make the movement of the main valve core 31 more stable. For example, the second elastic elements 33 can be helical springs, and the two second elastic elements 33 have the same size and elastic force.

[0040] Specifically, such as Figure 1 and Figure 2 As shown, the main valve body 32 includes a left valve cover 321 and a right valve cover 322. One end of a second elastic member 33 abuts against the left valve cover 321, and the other end abuts against the left side of the main valve core 31. One end of the other second elastic member 33 abuts against the right valve cover 322, and the other end abuts against the right side of the main valve core 31.

[0041] Optionally, the pilot valve 2 further includes a first seal (not shown), which is disposed between the pilot valve core 23 and the pilot valve body 21. The main valve 3 further includes a second seal (not shown), which is disposed between the main valve core 31 and the main valve body 32. For example, the first and second seals can be rubber rings, which can improve the sealing performance of the pilot valve core 23 and the main valve core 31, and reduce the wear of the pilot valve core 23 and the main valve core 31.

[0042] For example, the pilot valve 2 of the fluid cylinder in an embodiment of the present invention can be a three-position four-way valve.

[0043] like Figure 1 and Figure 2 As shown, the working principle of the fluid cylinder in an embodiment of the present invention is as follows.

[0044] (1) When the current of the proportional electromagnet 4 increases, the piston rod 12 retracts.

[0045] When the current of the proportional electromagnet 4 increases, the output force exceeds the force of the first elastic element 24, causing the pilot valve core 23 to move horizontally to the left. This connects channels c and a, and channels e, d, and b. The high-pressure liquid entering from port P flows through channels c and a into the left chamber of the main valve core 31. The main valve core 31 is pushed to the right by the high-pressure liquid in the left chamber, and the liquid in its right chamber flows through channels e, d, and b to port T, returning to the liquid tank.

[0046] After the main valve core 31 moves to the right, port P connects to channel g, and port T connects to channel f. The high-pressure liquid at port P reaches the left chamber of piston rod 12 through channel g, pushing piston rod 12 to the right. The liquid in the right chamber of piston rod 12 reaches port T through channel f and then flows back to the liquid tank.

[0047] When the piston rod 12 retracts, it drives the nut 132 to move to the right. The nut 132, through the threaded engagement, drives the lead screw 131 to rotate in the forward direction. When the lead screw 131 rotates in the forward direction, it drives the valve seat 22 to move to the right through the threaded engagement, compressing the first elastic element 24. When the force of the first elastic element 24 is equal to the force of the proportional electromagnet 4, it is no longer compressed, but instead moves the pilot valve core 23 to the right until the pilot valve core 23 returns to its initial position.

[0048] When the pilot valve core 23 returns to its initial position, channels c and a are disconnected, while channels a, e, d, and b are connected. The left chamber of the main valve core 31 is connected to port T via channels a, d, and b, and its right chamber is connected to port T via channels e, d, and b. Since the pressure in both the left and right chambers of the main valve core 31 is zero, it moves to the intermediate position under the action of the two second elastic elements 33.

[0049] When the main valve core 31 moves to the middle position, both channels g and f are in the closed state and are not connected to ports P and T. At this time, the piston rod 12 stops moving.

[0050] In this state, the pilot valve core 23 is in the same initial position as before the current change, and the change in length of the first elastic element 24 is equal to the displacement of the valve seat 22. The force of the first elastic element 24 is the same as the force of the proportional electromagnet 4, so kΔX = ΔF. Here, k is the spring stiffness, and ΔX is the change in spring length equal to the change in force of the proportional electromagnet 4.

[0051] Since the displacement of piston rod 12 is proportional to the rotation angle of lead screw 131, and the rotation angle of lead screw 131 is proportional to the displacement of valve seat 22, it can be concluded that the displacement of piston rod 12 is proportional to the force of proportional electromagnet 4. Furthermore, since the force of proportional electromagnet 4 is proportional to its current, it can be concluded that the displacement of piston rod 12 is proportional to the current of proportional electromagnet 4.

[0052] (2) When the current of the proportional electromagnet 4 decreases, the piston rod 12 extends.

[0053] The extension and retraction of piston rod 12 are similar. Specifically, the current of proportional electromagnet 4 decreases, causing pilot valve core 23 to move to the right, connecting channels c and e, and channels a, d, and b. Due to the high pressure in the right chamber, main valve core 31 moves to the left, connecting port P to channel f and port T to channel g, thus extending piston rod 123.

[0054] When the piston rod 12 extends, it drives the nut 1325 to move to the left. The nut 1325 drives the lead screw 1314 to rotate in the opposite direction. The lead screw 1314 drives the valve seat 228 to move to the left to release the first elastic element 24. When the force of the first elastic element 24 is equal to the force of the proportional electromagnet 4, the pilot valve core 23 moves to the left until it returns to the initial position.

[0055] The process after the pilot valve core 23 returns to its initial position is the same as the process after the pilot valve core 23 returns to its initial position during the retraction of the piston rod 12.

[0056] (3) Electrical signal feedback regulation

[0057] During the adjustment of the piston rod 12 position, the current value of the proportional electromagnet 4 does not abruptly change to the target value, but rather changes continuously at a certain slope. When the laser displacement sensor 5 detects that the piston rod 12 has reached the target position, the current value stops changing.

[0058] In summary, the technical effects of the fluid cylinder in the embodiments of the present invention are as follows.

[0059] The fluid cylinder in this embodiment of the invention has a mechanical feedback mechanism consisting of a screw pair and a first elastic element 24, which allows the valve core to move horizontally without rotation, thereby reducing wear on the seals on the pilot valve core 23, lowering the failure rate, and extending the maintenance cycle. Furthermore, the fluid cylinder in this embodiment of the invention uses dual feedback control consisting of mechanical feedback and electrical signal feedback. During the control process, the current of the proportional electromagnet 4 changes continuously, rather than abruptly changing to the target value, with synchronous mechanical feedback response. After the laser displacement sensor 5 detects that the piston rod 12 has reached the target position, the current stops changing. Compared to a stepper motor, the proportional electromagnet 4 used in the fluid cylinder of this embodiment of the invention has a simpler structure, lower cost, and can ensure the control accuracy of the fluid cylinder through dual feedback control of mechanical and electrical signals.

[0060] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to 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 limitations on this invention.

[0061] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0062] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0063] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0064] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0065] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A fluid cylinder characterized by, The utility model relates to a cylinder assembly, a pilot valve and a main valve, and belongs to the technical field of hydraulic systems. The cylinder assembly comprises a cylinder body, a piston rod and a transmission part, the piston rod extends from one end of the cylinder body, the transmission part extends from the other end of the cylinder body, the piston rod is connected with the transmission part, the piston rod is movable along the axial direction of the cylinder body to drive the transmission part to rotate relative to the cylinder body, the pilot valve comprises a pilot valve body, a valve seat, a first elastic member and a pilot valve spool, the pilot valve spool and the valve seat are arranged in the pilot valve body and are movable along the axial direction of the pilot valve body, the valve seat is rotationally connected with the pilot valve body, the transmission part is threadedly connected with the valve seat, the transmission part can drive the valve seat to move to push the pilot valve spool to move, the first elastic member is arranged in the pilot valve body and is arranged between the valve seat and the pilot valve spool, one end of the first elastic member is abutted against the valve seat, and the other end of the first elastic member is abutted against the pilot valve spool, the proportional solenoid is arranged at the end of the pilot valve spool away from the valve seat, and the proportional solenoid is used for driving the pilot valve spool to move towards the valve seat, the main valve comprises a main valve spool, a main valve body and two second elastic members, the main valve body is provided with a main valve cavity, the main valve spool is arranged in the main valve cavity and is movable along the axial direction of the main valve cavity, the pilot valve body is provided with a pilot valve cavity, the pilot valve cavity is communicated with the main valve cavity, the main valve cavity is communicated with a first flow channel and a second flow channel, the piston rod surrounds a first chamber and a second chamber which are independent of each other, the first flow channel is communicated with the first chamber, and the second flow channel is communicated with the second chamber, and the two second elastic members are arranged in the main valve body and are arranged on the two sides of the main valve spool in the axial direction, respectively, and the second elastic members press the main valve spool towards the main valve spool. The first elastic member is a spiral spring, the pilot valve further comprises a thrust bearing, the thrust bearing is arranged at the end of the valve seat adjacent to the pilot valve spool, one end of the thrust bearing is abutted against the valve seat, and the other end of the thrust bearing is connected with the first elastic member. The pilot valve body is provided with a pilot valve cavity and a guide channel which are communicated, the pilot valve spool is arranged in the pilot valve cavity, the guide channel comprises a first section and a second section which are coaxially connected, the second section is arranged between the first section and the pilot valve cavity, a stepped surface is arranged between the second section and the first section, at least part of the valve seat is rotationally arranged on the first section and is movable along the axial direction of the first section, the valve seat can abut against the stepped surface to limit the axial movement of the valve seat, and the first elastic member is arranged in the second section. ​ 2. The fluid cylinder of claim 1, wherein, ​ 3. The fluid cylinder of claim 1, wherein, ​ 4. The fluid cylinder of claim 1, wherein, The transmission component comprises a screw rod and a nut, one end of the piston rod is provided with a mounting cavity towards the pilot valve, the nut is arranged at the opening of the mounting cavity, one end of the screw rod is arranged in the mounting cavity and is in threaded cooperation with the nut, the other end of the screw rod is pivotally connected with the cylinder body, the other end of the screw rod extends out of the cylinder body and is in threaded cooperation with the valve seat.

5. The fluid cylinder of claim 1, wherein, The fluid cylinder further comprises a laser displacement sensor arranged on the cylinder body, the laser displacement sensor is used for detecting the extension position of the piston rod.

6. Fluid cylinder according to any of claims 1 to 5, characterized in that The pilot valve further comprises a first sealing element arranged between the pilot valve core and the pilot valve body. And / or, the main valve further comprises a second sealing element arranged between the main valve core and the main valve body.

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