A two-stage telescopic digital fluid cylinder

Abstract

The application discloses a two-stage telescopic digital fluid cylinder which comprises a primary cylinder barrel, a primary cylinder piston, a primary cylinder piston rod, a cylinder bottom cover, a secondary cylinder piston, a secondary cylinder piston rod, a cylinder end cover, a valve body connecting piece, a servo valve block, a motor, a transmission shaft and a pull wire sensor. According to the digital fluid cylinder, long-stroke working condition requirements can be met and high-precision position control can be realized under the condition that the installation space size is strictly limited.

Description

TECHNICAL FIELD

[0001] The present application relates to a two-stage telescopic digital fluid cylinder, belonging to the technical field of digital hydraulic cylinders. BACKGROUND

[0002] The fluid cylinder is a kind of terminal actuator that realizes linear reciprocating motion by converting the pressure energy of fluid (liquid or gas) into mechanical energy. The traditional fluid cylinder must be combined with a fluid control valve (directional valve, pressure valve, flow valve, servo valve, etc.) to realize position control, speed control, direction control and other practical functions. Its main shortcomings are complex system structure, high price, inconvenient use and maintenance, high requirement for technical personnel, and it cannot be directly controlled by a digital computer.

[0003] The digital fluid cylinder is fundamentally different from the traditional fluid cylinder. It is a kind of linear actuator that integrates energy conversion function and control function. In the medium and low frequency range, it is much better than the traditional fluid cylinder in terms of practical functions and control performance.

[0004] The existing digital fluid cylinder adopts a lead screw for position feedback, and its installation size and working stroke are limited by the length of the lead screw, which is not suitable for occasions with small installation space and long stroke requirements, such as telescopic arms of cranes. Moreover, long-span lead screws have the problems of large deflection and large cumulative error, which reduce the precision of the digital fluid cylinder. SUMMARY

[0005] In view of the problems existing in the prior art, the purpose of the present application is to provide a two-stage telescopic digital fluid cylinder that can meet the working condition requirements of long stroke and realize high-precision position control under the condition that the installation space size is strictly limited. To achieve the above purpose, the present application adopts the following scheme: a two-stage telescopic digital fluid cylinder comprises a primary cylinder barrel, a primary cylinder piston, a primary cylinder piston rod, a cylinder bottom cover, a secondary cylinder piston, a secondary cylinder piston rod, a cylinder end cover, a valve body connecting piece, a servo valve block, a motor, a transmission shaft and a pull wire sensor. The primary cylinder barrel is sleeved on the primary cylinder piston, and the primary cylinder piston is sleeved on the primary cylinder piston rod. The primary cylinder barrel and the primary cylinder piston are connected by dynamic sealing, the primary cylinder piston and the primary cylinder piston rod are connected by threads, and the primary cylinder piston rod and the piston rod extension end of the primary cylinder barrel are connected by dynamic sealing. The extension end of the primary cylinder piston rod is nested with the cylinder bottom cover and connected by threads. The primary cylinder piston rod is sleeved on the secondary cylinder piston, and the secondary cylinder piston is sleeved on the secondary cylinder piston rod. The primary cylinder piston rod and the secondary cylinder piston are connected by dynamic sealing, the secondary cylinder piston and the secondary cylinder piston rod are connected by threads, and the secondary cylinder piston rod and the cylinder bottom cover are connected by dynamic sealing. The non-piston rod extension end of the primary cylinder barrel and the cylinder end cover, the valve body connecting piece are connected by bolts in sequence.

[0006] The other end of the valve body connector is fixedly connected with the servo valve block through bolts. The servo valve block externally comprises an oil inlet port P, an oil return port T, a first working oil port A and a second working oil port B. The first working oil port A is connected with a first oil port e at the non-piston rod extending end of the first stage cylinder through an oil pipe, and the first working oil port A is connected with a rodless chamber of the first stage cylinder. The rodless chamber of the first stage cylinder is connected with a rodless chamber of the second stage cylinder through a second oil port f on the piston of the first stage cylinder. The second working oil port B is connected with a third oil port g at the piston rod extending end of the first stage cylinder through an oil pipe, and the working oil port B is connected with a rod chamber of the first stage cylinder. The piston rod of the first stage cylinder is provided with a fourth oil port h near the piston end, and a fifth oil port i and an internal oil passage are formed in the interior of the piston rod near the cylinder bottom cover end. The fourth oil port h in the rod chamber of the first stage cylinder is connected with the fifth oil port i in the rod chamber of the second stage cylinder through the internal oil passage of the piston rod, and the rod chamber of the second stage cylinder is connected with the rod chamber of the first stage cylinder.

[0007] The servo valve block internally comprises a valve sleeve, which is in gap sealing cooperation with the inner wall of the valve body. The valve sleeve is axially positioned through the internal shoulder of the valve body and the valve end cover, and the valve sleeve cannot move in the axial direction. A spool valve core is coaxially arranged in the valve sleeve, and the spool valve core is in gap sealing cooperation with the interior of the valve sleeve and can move in the axial direction. The spool valve core can be a four-edge spool valve core or a double-edge spool valve core.

[0008] The spool valve core adopts a four-edge spool valve core. The four-edge spool valve core moves axially to form four variable throttling openings with the four-edge spool valve sleeve. The four variable throttling openings can be divided into oil inlet throttling openings and oil return throttling openings. The oil inlet throttling openings are two variable throttling openings arranged in the middle of the four-edge spool valve core and are connected with the oil inlet port P and the first working oil port A and the oil inlet port P and the second working oil port B respectively. The oil return throttling openings are two variable throttling openings arranged at the two ends of the four-edge spool valve and are connected with the oil return port T and the first working oil A and the oil return port T and the second working oil port B respectively. The oil inlet throttling openings and the oil return throttling openings can be two groups according to the working state. The first group is the oil inlet throttling opening connected with the oil inlet port P and the first working oil port A and the oil return throttling opening connected with the oil return port T and the second working oil port B. The second group is the oil inlet throttling opening connected with the oil inlet port P and the second working oil port B and the oil return throttling opening connected with the oil return port T and the first working oil port A. When one group of throttling openings is opened, the other group of throttling openings is closed. The opened throttling openings control the inlet and outlet flow of the rodless chamber and the rod chamber of the primary and secondary cylinders by changing the opening area. Because the secondary cylinder is an asymmetric cylinder, the inlet and outlet flow of the rodless chamber and the rod chamber of the primary and secondary cylinders are not equal, so the opening area of the oil inlet and return throttling openings of each group should also be different, and the four-edge spool valve is an asymmetric four-edge spool valve. The asymmetric four-edge spool valve can be realized in two ways. One way is to open two groups of sleeve windows on the sleeve. The sleeve window shape can be a circular window, a rectangular window or a U-shaped window. The other way is to open two groups of grooves on the spool valve core. The grooves can be circular grooves, rectangular grooves or U-shaped grooves.

[0009] The spool valve core adopts a double-edge spool valve core. The double-edge spool valve core moves axially to form two variable throttling openings with the valve sleeve. The two throttling openings can be divided into oil inlet throttling openings and oil return throttling openings. The throttling opening between the first working oil port A and the oil inlet port P is the oil inlet throttling opening. The throttling opening between the first working oil port A and the oil return port T is the oil return throttling opening. The second working oil port B is directly connected with the oil inlet port P through the internal oil channel of the valve block. The variable throttling openings can have two forms. One form is to open sleeve windows on the sleeve. The sleeve window shape is a circular window, a rectangular window or a U-shaped window. The other form is to open grooves on the spool valve core. The groove shape is a circular groove, a rectangular groove or a U-shaped groove.

[0010] One end of the spool valve core is the driving end, and the other end is the free end. The driving end of the spool valve core is connected with one end of the shaft coupling through a key, and the spool valve core has only the freedom of axial sliding relative to the shaft coupling. The other end of the shaft coupling is fixedly connected with the motor output shaft, the motor output shaft drives the spool valve core to rotate through the shaft coupling, and the rotational angular displacement of the motor output shaft is the same as that of the spool valve core. The motor is fixed on the motor base through bolts. The motor can be a servo motor or a stepper motor. The motor base is fixed on the servo valve block through bolts.

[0011] The free end of the spool valve core is connected with one end of the transmission shaft through thread. The end of the transmission shaft connected with the free end of the spool valve core is the driving end, and the other end is the free end. The transmission shaft passes through the bearing seat hole opened in the center of the cylinder end cover. The transmission shaft is fixedly connected with the inner ring of the bearing through interference fit, and is axially positioned through the shaft shoulder and the bearing retainer. The outer ring of the bearing is in transition fit with the bearing seat hole of the cylinder end cover, and is axially positioned through the bearing seat hole shoulder and the bearing end cover. The bearing end cover is fixedly connected to the outside of the cylinder end cover through bolts. The transmission shaft can only rotate and cannot move axially, and the free end of the transmission shaft is connected with the pull wire sensor.

[0012] The pull wire sensor comprises a rotating shaft, a rotating disc, a steel wire rope, a steering roller and a pull wire spring. One end of the rotating shaft is fixedly connected with the free end of the transmission shaft through a cylindrical pin, and the other end of the rotating shaft is fixedly connected with the rotating disc through interference fit, and the rotating shaft and the rotating disc can only rotate together with the transmission shaft. The rotating disc is fixedly connected with one end of the steel wire rope, and a certain number of turns of the steel wire rope are wound on the circumference of the rotating disc. The other end of the steel wire rope changes direction through the steering roller, axially passes through the primary cylinder piston, and is fixedly connected with the secondary cylinder piston. The pull wire spring comprises a pull wire spring shell, a pull wire spring base and a clock spring. The pull wire spring shell and the pull wire spring base are both provided with a circular hole with a diameter larger than that of the rotating shaft, are coaxially sleeved on the rotating shaft, form a circular annular cavity, and are fixedly connected to the inside of the cylinder end cover through bolts. The clock spring is arranged in the circular annular cavity, the outer ring of the clock spring is fixedly connected with the pull wire spring shell in a mechanical embedding mode, and the inner ring of the clock spring is also fixedly connected with the rotating shaft in a mechanical embedding mode. The inner and outer rings of the clock spring are fixed, and can only rotate together with the rotating shaft. The clock spring is always tightened, and keeps the steel wire rope in a taut state.

[0013] Compared with the prior art, the beneficial effects of the present application are that the two-stage telescopic digital fluid cylinder meets the working condition requirements of long stroke and realizes high-precision position control under the condition that the installation space size is strictly limited. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a sectional view of the front view of the first embodiment of the two-stage telescopic digital fluid cylinder of the present application;

[0015] Figure 2 is Figure 1 the enlarged view of C in

[0016] Figure 3 is Figure 1 the enlarged view of D in

[0017] Figure 4 is Figure 1 the enlarged view of E in

[0018] Figure 5 is a schematic diagram of an asymmetric four-sided spool of embodiment one of a two-stage telescopic digital fluid cylinder of the present invention;

[0019] Figure 6 is a schematic diagram of an asymmetric four-sided spool of embodiment two of a two-stage telescopic digital fluid cylinder of the present invention;

[0020] Figure 7 is a schematic diagram of an asymmetric four-sided spool of embodiment three of a two-stage telescopic digital fluid cylinder of the present invention;

[0021] Figure 8 is a schematic diagram of an asymmetric four-sided spool of embodiment four of a two-stage telescopic digital fluid cylinder of the present invention;

[0022] Figure 9 is a cross-sectional view of a double-sided spool of embodiment five of a two-stage telescopic digital fluid cylinder of the present invention;

[0023] Figure 10 is a schematic diagram of a double-sided spool of embodiment five of a two-stage telescopic digital fluid cylinder of the present invention;

[0024] Figure 11 is a schematic diagram of a double-sided spool of embodiment six of a two-stage telescopic digital fluid cylinder of the present invention;

[0025] Figure 12 is a schematic diagram of a double-sided spool of embodiment seven of a two-stage telescopic digital fluid cylinder of the present invention;

[0026] Figure 13 is a schematic diagram of a double-sided spool of embodiment eight of a two-stage telescopic digital fluid cylinder of the present invention;

[0027] In the diagram, 1-motor, 2-motor mount, 3-four-sided spool valve block, 4-drive shaft, 5-valve body connector, 6-cylinder end cover, 7-first-stage cylinder barrel, 8-first-stage cylinder piston, 9-first-stage cylinder piston rod, 10-second-stage cylinder piston, 11-second-stage cylinder piston rod, 12-cylinder bottom cover, 13-coupling, 14-key, 15-valve end cover, 16-four-sided spool valve core, 17-four-sided spool valve sleeve, 18-bearing end cover, 19-bearing retaining ring, 20-bearing, 21-cylindrical pin, 22-coil spring base, 23-spring spring, 24-coil spring housing, 25-turntable, 2 6-Wire rope, 27-Steering roller, 28-Shaft, 29-Double-sided spool valve block, 30-Double-sided spool valve sleeve, 31-Double-sided spool valve core, 32-Four-sided spool valve return throttle port 1, 33-Four-sided spool valve inlet throttle port 1, 34-Four-sided spool valve inlet throttle port 2, 35-Four-sided spool valve return throttle port 2, 36-Double-sided spool valve inlet throttle port, 37-Double-sided spool valve return throttle port, e-First oil port, f-Second oil port, g-Third oil port, h-Fourth oil port, i-Fifth oil port, A-First working oil port, B-Second working oil port, P-Inlet oil port, T-Return oil port. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. The invention will now be described in further detail with reference to the accompanying drawings.

[0029] Example 1

[0030] like Figures 1 to 5 As shown, a two-stage telescopic digital fluid cylinder includes: a primary cylinder barrel 7, a primary cylinder piston 8, a primary cylinder piston rod 9, a cylinder bottom cover 12, a secondary cylinder piston 10, a secondary cylinder piston rod 11, a cylinder end cover 6, a valve body connector 5, a four-sided slide valve block 3, a motor 1, a drive shaft 4, and a pull-wire sensor. The primary cylinder barrel 7 is mounted on the primary cylinder piston 8, and the primary cylinder piston 8 is mounted on the primary cylinder piston rod 9. The primary cylinder barrel 7 and the primary cylinder piston 8 are dynamically sealed together, and the primary cylinder piston 8 and the primary cylinder piston rod 9 are threadedly connected. The primary cylinder piston rod 9 and the extended end of the piston rod of the primary cylinder barrel 7 are dynamically sealed together. The extended end of the primary cylinder piston rod 9 is internally nested within the cylinder bottom cover 12 and is threadedly connected to it. The primary cylinder piston rod 9 is mounted on the secondary cylinder piston 10, and the secondary cylinder piston 10 is mounted on the secondary cylinder piston rod 11. The first-stage cylinder piston rod 9 and the second-stage cylinder piston 10 are connected by a dynamic seal. The second-stage cylinder piston 10 and the second-stage piston rod 11 are connected by threads. The second-stage cylinder piston rod 11 and the cylinder bottom cover 12 are connected by a dynamic seal. The non-piston rod protruding end of the first-stage cylinder barrel 7 is sequentially connected to the cylinder end cover 6 and the valve body connector 5 by bolts.

[0031] The other end of the valve body connector 5 is fixed to the four-side spool valve block 3 by bolts. The four-side spool valve block 3 contains an oil inlet port P, an oil return port T, a first working oil port A and a second working oil port B. The first working oil port A is connected to the first oil port e on the non-piston rod end of the first cylinder cylinder barrel 7 through an oil pipe, and the first working oil port A is connected to the rodless chamber of the first cylinder. The rodless chamber of the first cylinder is connected to the rodless chamber of the second cylinder through the second oil port f on the first cylinder piston 8. The second working oil port B is connected to the third oil port g on the piston rod end of the first cylinder cylinder barrel 7 through an oil pipe, and the working oil port B is connected to the rod chamber of the first cylinder. The fourth oil port h is opened on the first cylinder piston rod 9 near the piston end, and the fifth oil port i and the internal oil passage are opened inside near the cylinder bottom cover 12. The fourth oil port h in the rod chamber of the first cylinder is connected to the fifth oil port i in the rod chamber of the second cylinder through the internal oil passage of the first cylinder piston rod 9, and the rod chamber of the second cylinder is connected to the rod chamber of the first cylinder.

[0032] The four-side spool valve block 3 contains a four-side spool valve sleeve 17, which is in gap sealing cooperation with the inner wall of the four-side spool valve block 3. The four-side spool valve sleeve 17 is axially positioned by the shoulder inside the four-side spool valve block 3 and the valve end cover 15, and the four-side spool valve sleeve 17 cannot move axially. The four-side spool valve sleeve 17 is coaxially provided with a four-side spool valve core 16, which is in gap sealing cooperation with the inside of the four-side spool valve sleeve 17, and the four-side spool valve core 16 can move axially.

[0033] The four-edge slide valve spool 16 moves axially to form four variable throttling orifices with the four-edge slide valve sleeve 17. The four variable throttling orifices can be divided into oil inlet throttling orifices (33, 34) and oil return throttling orifices (32, 35). The oil inlet throttling orifices (33, 34) are arranged in the middle of the four-edge slide valve spool, the oil inlet throttling orifice 34 is connected to the oil inlet port P and the first working oil port A, and the oil inlet throttling orifice 33 is connected to the oil inlet port P and the second working oil port B. The oil return throttling orifices (32, 35) are arranged at both ends of the four-edge slide valve, the oil return throttling orifice 35 is connected to the oil return port T and the first working oil port A, and the oil return throttling orifice 32 is connected to the oil return port T and the second working oil port B. The oil inlet throttling orifices (33, 34) and the oil return throttling orifices (32, 35) can be divided into two groups according to the working state. The first group is the oil inlet throttling orifice 34 and the oil return throttling orifice 32, and the second group is the oil inlet throttling orifice 33 and the oil return throttling orifice 35. When one group of throttling orifices is open, the other group of throttling orifices is closed. The open throttling orifices control the flow rate of the rodless chamber and the rod chamber of the primary and secondary cylinders by changing the opening area. Because the secondary cylinder is an asymmetric cylinder, the flow rates of the rodless chamber and the rod chamber of the primary and secondary cylinders are not equal, so the opening areas of the oil inlet and return throttling orifices of each group should also be different, and the four-edge slide valve is an asymmetric four-edge slide valve. The asymmetric four-edge slide valve is realized by opening two groups of rectangular windows or U-shaped windows on the sleeve.

[0034] One end of the four-edge slide valve spool 16 is the driving end, and the other end is the free end. The driving end of the four-edge slide valve spool 16 is connected to one end of the shaft coupling 13 through the key 14, and the four-edge slide valve spool 16 has only the freedom of axial sliding relative to the shaft coupling 13. The other end of the shaft coupling 13 is fixedly connected to the output shaft of the motor 1, and the output shaft of the motor 1 drives the four-edge slide valve spool 16 to rotate through the shaft coupling 13. The rotational angular displacement of the output shaft of the motor 1 is the same as the rotational angular displacement of the four-edge slide valve spool 16. The motor 1 is fixed on the motor base 2 by bolts, and the motor 1 can be a servo motor or a stepper motor. The motor base 2 is fixed on the four-edge slide valve block 3 by bolts.

[0035] The free end of the four-edge slide valve spool 16 is connected to one end of the transmission shaft 4 through threads. The end of the transmission shaft 4 connected to the free end of the four-edge slide valve spool 16 is the driving end, and the other end is the free end. The transmission shaft 4 passes through the bearing seat hole in the center of the cylinder end cover 6. The transmission shaft 4 is fixedly connected to the inner ring of the bearing 20 by interference fit, and is axially positioned by the shaft shoulder and the bearing retainer 19. The outer ring of the bearing 20 is in transition fit with the bearing seat hole of the cylinder end cover 6, and is axially positioned by the bearing seat hole shoulder and the bearing end cover 18. The bearing end cover 18 is fixed on the outside of the cylinder end cover 6 by bolts. The transmission shaft 4 can only rotate and cannot move axially, and the free end of the transmission shaft 4 is connected to the pull wire sensor.

[0036] The pull wire sensor comprises a rotating shaft 28, a rotating disc 25, a steel wire rope 26, a steering roller 27 and a pull wire spring. One end of the rotating shaft 28 is fixed to the free end of the transmission shaft 4 through a cylindrical pin 21, and the other end of the rotating shaft 28 is fixed to the rotating disc 25 through interference fit, so that the rotating shaft 28 and the rotating disc 25 can only rotate together with the transmission shaft 4. The rotating disc 25 is fixed to one end of the steel wire rope 26, and a certain number of turns of the steel wire rope 26 are wound on the circumference of the rotating disc 25. The other end of the steel wire rope 26 changes direction through the steering roller 27, axially penetrates the primary cylinder piston 8, and is fixed to the secondary cylinder piston 10. The pull wire spring comprises a pull wire spring shell 24, a pull wire spring base 22 and a clock spring 23. The pull wire spring shell 24 and the pull wire spring base 22 are both provided with a circular hole with a diameter larger than that of the rotating shaft 28, and are coaxially sleeved on the rotating shaft 28. The pull wire spring shell 24, the pull wire spring base 22 and the rotating shaft 28 form a circular annular cavity, which is fixed on the inner side of the cylinder end cover 6 through bolts. The clock spring 23 is coaxially arranged in the circular annular cavity, the outer circle of the clock spring 23 is fixed to the pull wire spring shell 24 in a mechanical embedding mode, and the inner circle of the clock spring 23 is also fixed to the rotating shaft 28 in a mechanical embedding mode. The inner and outer circles of the clock spring 23 are fixed, and can only rotate together with the rotating shaft 28. The clock spring 23 is always tightened, keeping the steel wire rope 26 in a taut state.

[0037] The following describes the use process of the present application with reference to the drawings: the present application is a two-stage telescopic digital fluid cylinder. Initially, the output shaft of the motor 1 is at zero position, the four-edge spool valve core 16 is at the middle position, and the primary cylinder piston rod 9 and the secondary cylinder piston rod 11 are both at the retracted limit state. There is a load on the secondary piston rod 11, and the load force is directed to the hydraulic cylinder along the axis.

[0038] A positive electric signal is input to the motor 1, and it is assumed that the motor shaft of the motor 1 rotates 1 degree clockwise from zero position, and the four-edge spool valve core 16 is also rotated 1 degree clockwise through the coupling 13. Since the free end of the four-edge spool valve core 16 is connected with the driving end of the transmission shaft 4 through a screw pair, the transmission shaft 4 cannot move axially, so the four-edge spool valve core 16 moves axially while rotating. It is assumed that the four-edge spool valve core 16 moves to the motor 1 direction, and the oil inlet throttle 34 and the oil return throttle 32 of the four-edge spool valve are opened. The high-pressure oil liquid enters the first-stage cylinder rodless chamber through the oil inlet P, the first working oil port A, the oil pipe and the first oil port e in turn, acts on the first-stage cylinder piston 8, and continues to enter the second-stage cylinder rodless chamber through the second oil port f, and acts on the second-stage cylinder piston 10. Since the area of the first-stage cylinder piston 8 is larger than that of the second-stage cylinder piston 10, the driving pressure of the first-stage cylinder overcoming the load is low, and the first-stage cylinder piston rod 9 is first stretched out. The oil liquid in the first-stage cylinder rod chamber flows back to the oil tank through the third oil port g, the oil pipe, the second working oil port B and the oil return port T in turn. At the same time, the steel wire rope 26 fixed on the second-stage cylinder piston 11 is lengthened as the first-stage cylinder piston rod 9 is stretched out. The steel wire rope 26 adjusts the direction through the steering roller 27 to drive the rotating disc 25 to rotate 1 degree clockwise. The rotating disc 25 drives the rotating shaft 28 to rotate 1 degree clockwise through interference fit, and the rotating shaft 28 drives the transmission shaft 4 to rotate 1 degree clockwise through the cylindrical pin 21. The transmission shaft 4 converts the rotation into axial movement and transmits it to the four-edge spool valve core 16 through the screw pair. Since the rotating angle of the transmission shaft 4 is equal to the rotating angle of the motor 1 and the directions are the same, the four-edge spool valve core 16 produces an equal-distance axial movement in the opposite direction, closes the throttle, the first-stage cylinder piston rod 9 stops stretching out, and one step-out process ends.

[0039] Continue to input a positive continuous electric signal to the motor 1, and the first-stage cylinder piston rod 9 is continuously stretched out. When the first-stage cylinder piston rod 9 contacts with the limiting shoulder of the first-stage cylinder cylinder 7, the first-stage cylinder piston rod 9 stops stretching out. The pressure in the first-stage and second-stage cylinder rodless chambers gradually rises, and when it reaches the driving pressure of the second-stage cylinder overcoming the load, the second-stage cylinder starts to act to push the second-stage cylinder piston rod 11 to stretch out, and the oil liquid in the second-stage cylinder rod chamber flows back to the oil tank through the fifth oil port i, the internal oil way of the first-stage piston rod 9, the fourth oil port h, the third oil port g, the second working oil port B and the oil return port T. The wire pulling sensor and the transmission shaft 4 continuously feed the sum of the displacement of the first-stage and second-stage pistons to the four-edge spool valve core 16 in the same way until the four-edge spool valve core 16 returns to the middle position, the first-stage and second-stage piston rods stop stretching out, and the continuous step-out process ends.

[0040] Continuing to input a reverse electrical signal to the motor 1, the motor 1 rotates counterclockwise by 1 degree, the four-edge slide valve spool 15 moves to the direction of the transmission shaft 4, and the oil inlet throttle 33 and the oil return throttle 35 of the four-edge slide valve are opened. The high-pressure oil liquid sequentially passes through the oil inlet P, the second working oil port B, the oil pipe and the second oil port g, enters the one-stage cylinder rod cavity, and continues to pass through the fourth oil port h, the one-stage cylinder piston rod 9 internal oil way and the fifth oil port i, and enters the two-stage cylinder rod cavity. The output force and the load force of the hydraulic cylinder are both axially directed to the hydraulic cylinder, and the one-stage and two-stage piston rods are retracted. Since the area of the two-stage cylinder piston 10 is smaller than the area of the one-stage cylinder piston 8, the pressure in the two-stage cylinder rodless cavity is large, and the oil liquid is discharged first, and the two-stage cylinder piston rod 11 is retracted first. The oil liquid in the two-stage cylinder rodless cavity sequentially passes through the second oil port f, the first oil port e, the oil pipe, the first working oil port A and the oil return port T, and flows back to the oil tank. In the retraction process of the two-stage cylinder piston rod 11, the clock spring 23 drives the rotating disc 25 to rotate counterclockwise by 1 degree through the rotating shaft 28 to recover the steel wire rope 26. At the same time, the rotating shaft 28 drives the transmission shaft 4 to rotate through the cylindrical pin 21, and the transmission shaft 4 also rotates counterclockwise by 1 degree. Since the rotation angle of the transmission shaft 4 and the rotation angle of the motor 1 are equal in size and the same in direction, the four-edge slide valve spool 16 generates reverse equidistance axial movement, closes the throttle, the two-stage cylinder piston rod 11 stops retracting, and one step of retraction is completed.

[0041] Continuing to input a reverse electrical signal to the motor 1, the motor 1 rotates counterclockwise by 1 degree, the four-edge slide valve spool 15 moves to the direction of the transmission shaft 4, and the oil inlet throttle 33 and the oil return throttle 35 of the four-edge slide valve are opened. The high-pressure oil liquid sequentially passes through the oil inlet P, the second working oil port B, the oil pipe and the second oil port g, enters the one-stage cylinder rod cavity, and continues to pass through the fourth oil port h, the one-stage cylinder piston rod 9 internal oil way and the fifth oil port i, and enters the two-stage cylinder rod cavity. The output force and the load force of the hydraulic cylinder are both axially directed to the hydraulic cylinder, and the one-stage and two-stage piston rods are retracted. Since the area of the two-stage cylinder piston 10 is smaller than the area of the one-stage cylinder piston 8, the pressure in the two-stage cylinder rodless cavity is large, and the oil liquid is discharged first, and the two-stage cylinder piston rod 11 is retracted first. The oil liquid in the two-stage cylinder rodless cavity sequentially passes through the second oil port f, the first oil port e, the oil pipe, the first working oil port A and the oil return port T, and flows back to the oil tank. In the retraction process of the two-stage cylinder piston rod 11, the clock spring 23 drives the rotating disc 25 to rotate counterclockwise by 1 degree through the rotating shaft 28 to recover the steel wire rope 26. At the same time, the rotating shaft 28 drives the transmission shaft 4 to rotate through the cylindrical pin 21, and the transmission shaft 4 also rotates counterclockwise by 1 degree. Since the rotation angle of the transmission shaft 4 and the rotation angle of the motor 1 are equal in size and the same in direction, the four-edge slide valve spool 16 generates reverse equidistance axial movement, closes the throttle, the two-stage cylinder piston rod 11 stops retracting, and one step of retraction is completed.

[0042] In the extension and retraction of the one-stage and two-stage piston rods, the displacement signals are fed back to the four-edge slide valve spool 16 through the pull wire sensor and the transmission shaft 4, so that the displacement of the one-stage and two-stage piston rods is linearly proportional to the rotation angle of the motor 1, and the larger the rotation angle of the motor 1, the larger the displacement of the one-stage and two-stage piston rods.

[0043] Example Two

[0044] In combination Figure 6 The implementation mode of the asymmetric four-edge slide valve in Example One is replaced by opening circular windows on the valve sleeve, that is, two large circular windows and two small circular windows are opened on the four-edge slide valve sleeve 17. The large circular windows are connected with the hydraulic cylinder rodless cavities, and the small circular windows are connected with the hydraulic cylinder rod cavities.

[0045] Example Three

[0046] In combinationFigure 7 The implementation of the asymmetric four-edge spool valve in Example One is replaced by opening unequal size rectangular slots or U-shaped slots on the shoulder of the four-edge spool valve spool 16. When the four-edge spool valve spool 16 is in the neutral position, the shoulder of the four-edge spool valve spool 16 closes the window on the four-edge spool valve sleeve 17. When the four-edge spool valve spool 16 moves, the edges of the rectangular slots or U-shaped slots on the shoulder of the four-edge spool valve spool 16 communicate with the window on the four-edge spool valve sleeve 17, forming a throttling orifice. The large rectangular slots or U-shaped slots communicate with the rodless chamber of the hydraulic cylinder, and the small rectangular slots or U-shaped slots communicate with the rod chamber of the hydraulic cylinder.

[0047] Example Four

[0048] In combination Figure 8 The implementation of the asymmetric four-edge spool valve in Example One is replaced by opening unequal size circular slots on the shoulder of the four-edge spool valve spool 16. When the four-edge spool valve spool 16 is in the neutral position, the shoulder of the four-edge spool valve spool 16 closes the window on the four-edge spool valve sleeve 17. When the four-edge spool valve spool 16 moves, the edges of the circular slots on the shoulder of the four-edge spool valve spool 16 communicate with the window on the four-edge spool valve sleeve 17, forming a throttling orifice. The large circular slots communicate with the rodless chamber of the hydraulic cylinder, and the small circular slots communicate with the rod chamber of the hydraulic cylinder.

[0049] Example Five

[0050] In combination Figure 9 And Figure 10 The asymmetric four-edge spool valve in Example One is replaced by a double-edge spool valve. The double-edge spool valve includes a double-edge spool valve block 29, a double-edge spool valve sleeve 30, and a double-edge spool valve spool 31. The double-edge spool valve block 29 has a first working oil port A and a second working oil port B opened on the outside. The first working oil port A is connected to the rodless chamber of the hydraulic cylinder, and the second working oil port B is connected to the rod chamber of the hydraulic cylinder. The double-edge spool valve block 29 has an oil passage opened inside, directly connecting the oil inlet P and the second working oil port B. The double-edge spool valve sleeve 30 is nested inside the double-edge spool valve block 29, and the double-edge spool valve sleeve 30 is in gap sealing cooperation with the inner wall of the double-edge spool valve block 29. The double-edge spool valve sleeve 30 is axially positioned by the inner shoulder of the double-edge spool valve block 29 and the valve end cover 15, and the double-edge spool valve sleeve 30 does not move on the axis. The double-edge spool valve spool 31 is coaxially arranged inside the double-edge spool valve sleeve 30, and the double-edge spool valve spool 31 is in gap sealing cooperation with the inside of the double-edge spool valve sleeve 30, and the double-edge spool valve spool 31 can move axially. When the double-edge spool valve spool 31 moves axially, it forms two variable throttling orifices with the double-edge spool valve sleeve 30, which are the oil inlet throttling orifice 36 between the oil inlet P and the first working oil port A and the oil return throttling orifice 37 between the oil return port T and the first working oil port A. The throttling orifice form of the double-edge spool valve adopts rectangular windows or U-shaped windows opened on the sleeve.

[0051] When the double-sided spool 31 moves towards the motor 1, the inlet throttle 36 opens and the return throttle 37 closes. The rod cavity and the rodless cavity of the hydraulic cylinder are connected to high pressure oil. The hydraulic cylinder and the double-sided spool form a differential connection, which pushes the primary cylinder piston rod 9 to extend. When the primary cylinder piston rod 9 reaches the limit, the secondary cylinder piston rod 11 extends.

[0052] When the double-sided spool 31 moves towards the transmission shaft 4, the inlet throttle 36 closes and the return throttle 37 opens. The rodless cavity of the hydraulic cylinder is connected to the return port T, and the rod cavity is connected to the inlet port P. Under the joint action of the load force and the hydraulic pressure, the secondary cylinder piston rod 11 retracts first, and then the primary cylinder piston rod 9 retracts after the secondary cylinder piston 10 and the primary cylinder piston 8 contact.

[0053] When the primary and secondary piston rods extend and retract, the displacement signals are fed back to the double-sided spool 31 through the pull wire sensor and the transmission shaft 4, so that the displacement of the primary and secondary piston rods is linearly proportional to the rotation angle of the motor 1. The greater the rotation angle of the motor 1, the greater the displacement of the primary and secondary piston rods.

[0054] Example Six

[0055] In combination Figure 11 The throttle form of the double-sided spool in Example Five is replaced by a circular window on the valve sleeve.

[0056] Example Seven

[0057] In combination Figure 12 The throttle form of the double-sided spool in Example Five is replaced by a rectangular slot or a U-shaped slot on the spool.

[0058] Example Eight

[0059] In combination Figure 13 The throttle form of the double-sided spool in Example Five is replaced by a circular slot on the spool.

[0060] The schemes in the examples are not intended to limit the patent protection scope of the present application. Any equivalent implementation or modification that does not deviate from the present application is included in the patent scope of the present application.

Claims

1. A two-stage telescopic digital fluid cylinder, comprising: The system comprises a primary cylinder barrel, a primary cylinder piston, a primary cylinder piston rod, a secondary cylinder piston, a secondary cylinder piston rod, a cylinder bottom cover, a cylinder end cover, a valve body connector, a servo valve block, a motor, a drive shaft, and a pull-wire sensor. The primary cylinder barrel is fitted onto the primary cylinder piston, and the primary cylinder piston is fitted onto the primary cylinder piston rod. The primary cylinder barrel and the primary cylinder piston are connected by a dynamic seal, and the primary cylinder piston and the primary cylinder piston rod are fixedly connected by threads. The extended end of the primary cylinder piston rod is connected to the extended end of the primary cylinder barrel by a dynamic seal. The cylinder bottom cover is nested inside the extended end of the primary cylinder piston rod and fixedly connected by threads. The primary cylinder piston rod is fitted onto the secondary cylinder piston, and the secondary cylinder piston is fitted onto the secondary cylinder piston rod. The primary cylinder piston rod and the secondary cylinder piston are connected by a dynamic seal. The second-stage cylinder piston and piston rod are fixedly connected by threads, and the second-stage cylinder piston rod is dynamically sealed to the cylinder bottom cover. The non-piston rod protruding end of the first-stage cylinder barrel is sequentially fixed to the cylinder end cover and valve body connecting piece by bolts. The servo valve block contains a valve sleeve, which is sealed to the inner wall of the valve body by a clearance seal. The valve sleeve is axially positioned by the internal shoulder of the valve body and the valve end cover, and the valve sleeve will not move on the axis. A spool valve core is coaxially arranged inside the valve sleeve, and the spool valve core is sealed to the inside of the valve sleeve by a clearance seal, allowing the spool valve core to move axially. The spool valve core is a four-sided spool valve core or a double-sided spool valve core. The free end of the spool valve core is threaded to one end of the drive shaft. The end of the drive shaft connected to the free end of the spool valve core is the drive end. One end is a free end; the drive shaft passes through the center of the cylinder end cover and is connected to the cylinder end cover via a bearing; the outer ring of the bearing is fixed to the bearing seat of the cylinder end cover with an interference fit, and is axially positioned by the bearing seat shoulder and the bearing end cover; the bearing end cover is fixed to the outside of the cylinder end cover by bolts; the inner ring of the bearing is fixed to the drive shaft with an interference fit, and is axially positioned by the shaft shoulder and the bearing retaining ring; the drive shaft can only rotate and cannot move axially; the free end of the drive shaft is connected to a pull-wire sensor; the pull-wire sensor includes a rotating shaft, a turntable, a steel wire rope, a steering roller, and a pull-wire spring; one end of the rotating shaft is fixed to the free end of the drive shaft via a cylindrical pin, and the other end of the rotating shaft is fixed to the turntable with an interference fit; the rotating shaft and the turntable can only rotate together with the drive shaft; The turntable is fixedly connected to one end of the wire rope, and a certain number of turns of the wire rope are wound around the circumference of the turntable; the other end of the wire rope changes direction through a steering roller, passes axially through the piston of the first-stage cylinder, and is fixedly connected to the piston of the second-stage cylinder; the pull spring includes a pull spring housing, a pull spring base, and a spring; both the pull spring housing and the pull spring base have circular holes with a diameter larger than the diameter of the rotating shaft, and are coaxially fitted onto the rotating shaft, forming a circular cavity, and are fixed to the inside of the cylinder end cover by bolts; the spring is placed in the circular cavity, and the outer ring of the spring is mechanically embedded and fixedly connected to the pull spring housing, and the inner ring of the spring is also mechanically embedded and fixedly connected to the rotating shaft; both the inner and outer rings of the spring are fixed and can only rotate together with the rotating shaft;The spring is always wound tight, keeping the wire rope taut.

2. The two-stage telescopic digital fluid cylinder according to claim 1, characterized in that: The other end of the valve body connector is fixedly connected to the servo valve block by bolts; the servo valve block includes an oil inlet P, an oil return T, a first working oil port A, and a second working oil port B; the first working oil port A is connected to the first oil port e at the non-piston rod extension end of the first-stage cylinder barrel through an oil pipe, and the first working oil port A is connected to the rodless chamber of the first-stage cylinder, and the rodless chamber of the first-stage cylinder is connected to the rodless chamber of the second-stage cylinder through the second oil port f on the piston of the first-stage cylinder; the second working oil port B is connected to the third oil port g at the piston rod extension end of the first-stage cylinder barrel through an oil pipe, and the working oil port B is connected to the rod chamber of the first-stage cylinder; the piston rod of the first-stage cylinder has a fourth oil port h near the piston end, and a fifth oil port i and an internal oil passage are provided inside near the cylinder bottom cover end; the fourth oil port h in the rod chamber of the first-stage cylinder is connected to the fifth oil port i in the rod chamber of the second-stage cylinder through the internal oil passage of the piston rod of the first-stage cylinder, and the rod chamber of the second-stage cylinder is connected to the rod chamber of the first-stage cylinder.

3. The two-stage telescopic digital fluid cylinder according to claim 1, characterized in that: The spool valve core is a four-sided spool valve core; when the four-sided spool valve core moves axially, it forms four variable throttling ports with the valve sleeve; the four variable throttling ports can be divided into inlet throttling ports and return throttling ports; the inlet throttling ports are two variable throttling ports arranged in the middle of the four-sided spool valve core, respectively connecting inlet port P to the first working port A and inlet port P to the second working port B; the return throttling ports are two variable throttling ports arranged at both ends of the four-sided spool valve, respectively connecting return port T to the first working port A and return port T to the second working port B; the inlet throttling ports and return throttling ports can be in two sets according to the working state; The first group consists of an oil inlet throttle port connecting the oil inlet P and the first working oil inlet A, and a return oil throttle port connecting the return oil inlet T and the second working oil inlet B. The second group consists of an inlet throttling port connecting the inlet port P to the second working port B and a return throttling port connecting the return port T to the first working port A. When one group of throttling ports is open, the other group is closed. The open throttling ports control the flow rate of the rodless and rod chambers of the first and second stage cylinders by changing their opening area. Because the second stage cylinder is asymmetrical, the flow rates of the rodless and rod chambers of the first and second stage cylinders are unequal, so the opening areas of each group of inlet and return throttling ports are also different. The four-sided spool valve is an asymmetrical four-sided spool valve. The asymmetrical four-sided spool valve is implemented in two ways: one is by opening two sets of valve sleeve windows on the valve sleeve, the valve sleeve windows being circular, rectangular, or U-shaped windows; the other is by opening two sets of grooves on the spool valve core, the grooves being circular, rectangular, or U-shaped grooves.

4. A two-stage telescopic digital fluid cylinder according to claim 1, characterized in that: The spool valve core is a double-sided spool valve core; when the double-sided spool valve core moves axially, it forms two variable throttling ports with the valve sleeve; the two throttling ports can be divided into an oil inlet throttling port and an oil return throttling port; the oil inlet throttling port connects the oil inlet port P and the first working oil port A; the oil return throttling port connects the oil return port T and the first working oil port A; the variable throttling port has two forms, one form is to open a valve sleeve window on the valve sleeve, the valve sleeve window shape is a circular window, a rectangular window or a U-shaped window; the other form is to open a groove on the spool valve core, the groove shape is a circular groove, a rectangular groove or a U-shaped groove; the second working oil port B outside the servo valve block is directly connected to the oil inlet port P through the internal oil passage of the valve block.

5. A two-stage telescopic digital fluid cylinder according to claim 1, characterized in that: One end of the spool valve core is the driving end, and the other end is the free end. The driving end of the spool valve core is connected to one end of the coupling via a key, and the spool valve core has only the axial sliding degree of freedom relative to the coupling. The other end of the coupling is fixedly connected to the motor output shaft, and the motor output shaft drives the spool valve core to rotate through the coupling. The angular displacement of the motor output shaft is the same as the angular displacement of the spool valve core. The motor is fixed to the motor base by bolts, and the motor is a servo motor or a stepper motor. The motor base is fixed to the servo valve block by bolts.

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