A damping self-resetting hydraulic drive unit and its control method

Abstract

The present invention relates to a damping self-resetting hydraulic drive unit and its control method. The hydraulic drive unit includes a double-layer hydraulic cylinder, a rotary electromagnetic unloading device, and a hydrodynamic damping device. The double-layer hydraulic cylinder includes an inner and outer cylinder barrel, a piston, a piston rod, and an internal flow channel connector. The inner and outer cylinder barrels divide the space into a hydraulic chamber and a damping chamber. The rotary electromagnetic unloading device includes a porous sleeve connector, a rotary deflector, and a magnetic attraction winding. The porous sleeve connector is provided at both ends of the inner cylinder barrel and internally embedded with a rotary deflector to control the on / off of the internal oil passage. The hydrodynamic damping device includes a coil winding, a damping piston, a damping sleeve, a spring, and upper and lower end covers. The coil winding is located on the outer wall of the inner cylinder barrel. The damping piston separates the hydraulic oil from the magnetorheological fluid, uses hydrodynamic force to promote the circulation of the magnetorheological fluid, and generates the required damping force. The hydraulic drive unit and its control method can achieve self-resetting after impact, achieve continuous anti-impact load, and effectively improve the under-damping characteristics of the hydraulic system.

Description

Technical Field

[0001] The present invention relates to the field of hydraulic shock absorption design, and particularly to a damping self-resetting hydraulic drive unit and a control method thereof. Background Art

[0002] Magnetorheological fluid is a new type of intelligent control material. Under the action of a magnetic field, magnetic particles form a chain-like arrangement along the magnetic field direction. When the moving direction is perpendicular to the magnetic field direction, an anti-shear yield stress is generated. By using this property, a magnetorheological fluid shock absorber is made. With the input current as the control signal, different damping forces are generated through the action of the magnetic field of the coil winding to adapt to different impact loads.

[0003] The hydraulic cylinder system has obvious underdamping characteristics. When a sudden load shock or a sudden oil shock acts on the piston rod or piston of the hydraulic cylinder, the displacement error fluctuation response time is relatively long. Especially for an external sudden load shock, it converts the impact force into oil pressure and reacts on the pump source, thereby causing pressure fluctuations in the entire hydraulic system and even damaging the pump source equipment. Currently, the research mainly improves the underdamping characteristics of the hydraulic system by means of parallel or series controllable damping: among them, the parallel structure designs the hydraulic cylinder and the damper on the same side. Such a design has a relatively large circumferential volume and requires a relatively strict working space; the series structure is to let the hydraulic cylinder and the damper share a piston rod, and the structure is relatively compact. However, the disadvantage that its axial design dimension is larger than twice the stroke makes it difficult to be applied in working occasions with a relatively large stroke of the hydraulic cylinder. For the existing structural designs, whether parallel or series, due to the existence of zero-field damping force in the magnetorheological damper, the hydraulic cylinder has a coupling relationship with the damper during the movement process, increasing the complexity of the control algorithm for the hydraulic cylinder, seriously affecting the control accuracy and response speed of the hydraulic cylinder, and even causing unnecessary energy waste. Summary of the Invention

[0004] The purpose of the present invention is to provide a damping self-resetting hydraulic drive unit and a control method thereof. The hydraulic drive unit and the control method can achieve self-resetting after impact, realize continuous anti-impact load, and effectively improve the underdamping characteristics of the hydraulic system.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a damping self-resetting hydraulic drive unit, including a double-layer hydraulic cylinder, a rotary electromagnetic unloading device, and a hydrodynamic damping device. The double-layer hydraulic cylinder includes an inner cylinder barrel, an outer cylinder barrel, a piston, a piston rod, and two inner flow channel connectors. A plurality of coil grooves are provided on the outer side of the inner cylinder barrel, and magnetic isolation grooves are provided on both sides of each coil groove. Rubber rings are provided in the magnetic isolation grooves to prevent the magnetic field of the coil winding from closing on the inner cylinder barrel. The inner cavity of the inner cylinder barrel is a hydraulic cavity, and the gap formed between the inner and outer cylinder barrels is a damping cavity. The piston divides the hydraulic cavity into upper and lower parts, and the two inner flow channel connectors are respectively communicated with the upper and lower parts of the hydraulic cavity;

[0006] The rotary electromagnetic unloading device includes two porous sleeve connectors, two rotary guide vanes, and two magnetic attraction windings. The two porous sleeve connectors are respectively nested at the upper and lower ends of the inner cylinder barrel. The rotary guide vanes are embedded on the bottom plate inside the porous sleeve connectors. The rotary guide vanes are annular structures with a central through hole. Circumferentially distributed round holes are correspondingly provided on the bottom plate of the porous sleeve connector and the annular part of the rotary guide vane, and the interval between the round holes is greater than the diameter of the round holes. A magnetic attraction winding is embedded in the middle of the bottom plate of the porous sleeve connector. A plurality of chip permanent magnets are embedded along the circumference of the inner circle of the annular part of the rotary guide vane. By the positive and negative voltages of the magnetic attraction winding, the rotary guide vane can be driven to rotate left and right, thereby realizing the on-off of the flow direction of the hydraulic oil. The fixed position of the magnetic attraction winding determines its rotation angle;

[0007] The hydrodynamic damping device includes a plurality of coil windings, two damping pistons, two damping sleeves, two springs, an upper end cover, and a lower end cover. The plurality of coil windings are respectively wound in the corresponding coil grooves on the outer wall of the inner cylinder barrel. After being energized, the magnetorheological fluid flowing through the damping cavity generates a damping force. The two damping sleeves are respectively nested at the upper end of the upper porous sleeve connector and the lower end of the lower porous sleeve connector. The upper end cover is installed at the upper end of the upper damping piston, and the lower end cover is installed at the lower end of the lower damping piston. The two springs are respectively installed between the damping piston and the upper end cover or the lower end cover. The damping piston can axially move in the damping sleeve and divides the inner cavity of the damping sleeve into a hydrodynamic cavity and a spring cavity. The hydraulic oil in the hydraulic cavity can flow into the hydrodynamic cavity through the conduction state of the porous sleeve connector. The high-pressure oil in the hydrodynamic cavity pushes the damping piston to move, so that the magnetorheological fluid in the spring cavity flows through the damping cavity to the spring cavity at the other end of the hydraulic drive unit, and at the same time pushes the damping piston at the other end to move in the same direction. At this time, the magnetorheological fluid flowing through the damping cavity generates a shear damping force due to the magnetorheological effect, thereby hindering the impact force of the high-pressure oil and playing a role in buffering and vibration reduction. The self-resetting function of the compression and damping piston is realized by using the pressure difference conversion between the two ends of the piston. Return grooves for conducting the spring cavity and the damping cavity are provided on both the upper and lower end covers.

[0008] Furthermore, a circular slide rail is provided inside the porous sleeve connector. The rotating deflector with a circular hole can rotate inside the circular slide rail. When the magnetic attraction winding is energized in the forward direction, the circular hole of the porous sleeve connector is aligned with the circular hole of the rotating deflector, and the hydraulic oil is in a conducting state. When the magnetic attraction winding is energized in the reverse direction, the circular hole of the porous sleeve connector is offset from the circular hole of the rotating deflector, and the hydraulic oil is in a disconnected state.

[0009] Furthermore, while the damping piston pushes the magnetorheological fluid to flow through the damping chamber, the spring is compressed, and the spring stores energy. When the pressure difference between the two ends of the piston in the hydraulic chamber decreases, the compressed spring pushes the damping piston to reset, and the magnetorheological fluid flows in the reverse direction. The damping force required during the operation of the damping chamber is generated. When the spring resets, the current of the coil winding is turned off, and no damping force is generated at this time.

[0010] Furthermore, connection holes are provided on the same side wall at both ends of the outer cylinder, and oil guiding holes are correspondingly provided on the inner cylinder. The connection holes and the circular holes are guaranteed to be concentric. The internal flow path connector passes through the connection holes and is communicated with the oil guiding holes on the inner cylinder, so that the hydraulic oil flows into the hydraulic chamber through the oil guiding holes on the inner cylinder.

[0011] Furthermore, the magnetic attraction windings are circumferentially distributed around the center of the porous sleeve connector and are fixed on the bottom plate of the porous sleeve connector through guide grooves. Their fixed positions also play a role in restricting the position of the rotating deflector. When energized, a magnetic field can be generated, and the adsorption or repulsion of the plate-shaped permanent magnet is realized through the magnetic fields generated by positive and negative voltages.

[0012] The present invention also provides a control method for the above-mentioned damping self-resetting hydraulic drive unit, including the following steps:

[0013] Step 1: Connect the wiring terminals of the coil winding and the magnetic attraction winding to the controller in sequence. A displacement sensor is installed outside the piston rod. The oil ports at the upper and lower ends of the hydraulic drive unit are connected to the hydraulic servo valve through oil pipes. It is set that when the oil pressure at the lower end is greater than the pressure at the upper end, Δ>0; on the contrary, Δ<0; when the oil pressure at the lower end is equal to the pressure at the upper end, Δ = 0.

[0014] Step 2: The magnetic attraction winding is energized in the reverse direction, the porous sleeve connector is in the blocking state, and the hydraulic oil enters the hydraulic chamber from the lower oil port, thereby pushing the piston and the piston rod to move upward. When the top of the piston rod is impacted by a sudden downward load, while the piston rod moves downward, the impact force received is transmitted to the hydraulic chamber at the lower end of the piston through the piston, and the pressure in the lower oil chamber suddenly increases, resulting in a larger pressure difference between the upper and lower oil chambers of the piston. At this time, a positive voltage is applied to the porous sleeve connectors at both ends, and the hydraulic chamber and the hydrodynamic chamber are quickly connected. Then, the high pressure causes the hydraulic oil in the hydrodynamic chamber to push the piston downward, thereby driving the magnetorheological fluid in the spring chamber to flow through the damping chamber, and then flowing back into the symmetric end spring chamber through the end cover return groove, and pushing the symmetric end spring to move downward. At this time, the coil winding is energized, and the input current of the coil winding is adjusted through the buffer control algorithm to control the damping force generated by the damping chamber, and then the pressure in the lower oil chamber of the piston is adjusted to reduce the impact of the oil fluid on the hydraulic servo system;

[0015] Step 3: When the sudden load disappears, a reverse voltage is applied to the magnetic attraction winding, the porous sleeve connector is closed, and it is recorded that the spring at the lower end is in the compressed state and the spring at the upper end is in the stretched state. The pressure difference signal at both ends of the hydraulic cylinder is collected. When Δ < 0 or Δ = 0, a positive voltage is applied to the magnetic attraction winding, the porous sleeve connector is conducted, and the compressed springs at both ends push the piston upward. The hydraulic oil in the chamber is discharged through the porous sleeve connector at the lower end, and part of the hydraulic oil in the hydraulic chamber is inhaled at the upper end. After the piston is reset, the magnetic attraction winding is energized in the reverse direction, the porous sleeve connector is blocked, and it enters the impact buffer waiting state;

[0016] Step 4: During the displacement accuracy control process, when a large oil pressure is applied, the piston is impacted by a large amount of oil fluid, and the piston rod generates a displacement fluctuation error. At this time, the porous sleeve connector is conducted, and the high-pressure oil fluid in the hydraulic chamber flows into the hydrodynamic chamber to achieve unloading. At the same time, the required damping force is generated through the buffer control algorithm to slow down the hydraulic impact, thereby improving the displacement fluctuation error. Finally, the self-resetting function is switched by judging the pressure difference at both ends.

[0017] Further, in Step 1, the number of coil windings is greater than two, the winding directions are the same, and they are axially arranged. In order to increase the magnetic field strength in the damping chamber gap, the positive and negative wiring methods of the connection terminals of adjacent coil windings are opposite.

[0018] Further, in Step 1, when impacted by a sudden load, in order to ensure the control accuracy and prevent the reverse impact of the oil fluid on the hydraulic servo system, the servo valve of the hydraulic cylinder is controlled to be in the closed state at this time, and all oil fluid circulation is carried out in the inner and outer chambers.

[0019] Further, in Steps 2 and 3, when the direction of the mutation load is upward, the spring at the upper end of the buffer is in a compressed state after being recorded. When Δ > 0 or Δ < 0, the magnetic attraction winding is energized in the forward direction, the piston resets, the magnetic attraction winding is energized in the reverse direction, and the porous sleeve connector is blocked, entering the impact buffer waiting state.

[0020] Further, during the process where the porous sleeve connector is conducting and cooperating with the buffer control algorithm for buffering, the judgment basis is the displacement error of the hydraulic cylinder during operation; within the allowable range of the displacement error, the magnitude of the current passing through the coil winding is continuously adjusted to improve the impact buffer effect.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention applies the controllable characteristics of the magnetorheological damper to the buffer and vibration reduction of the hydraulic cylinder, combines the damper with the hydraulic cylinder, improves the under-damping characteristics of the hydraulic system, uses the double-layer flow channel design of the inner and outer cylinder barrels, reduces the circumferential and axial structural design dimensions, uses the hydrodynamic drive to replace the co-rod structure to transmit the impact load, improves the compactness of the series structure, and at the same time, based on the theory that the impact buffer stroke is much smaller than the dynamic stroke of the hydraulic cylinder, shortens the axial structural dimension of the damper.

[0023] 2. The design of the rotary electromagnetic unloading device of the present invention controls the on-off of the hydraulic working area and the damping buffer area, realizes the mechanical decoupling of the real damper and the hydraulic cylinder, and at the same time symmetrically arranges the damper piston at both ends of the hydraulic drive unit, solves the problem of hydraulic volume balance at both ends of the piston in the inner circulation flow channel, and at the same time uses the return spring to realize the self-restoring function of the damping piston after buffering and shock absorption, completing the basic structural design for continuous anti-load impact.

[0024] 3. The design of the buffer-unloading continuous buffer control strategy of the present invention uses the pressure difference at both ends of the hydraulic cylinder and the displacement error of the piston rod, and by controlling the on-off state of the rotary electromagnetic unloading device, realizes the hydraulic unloading under sudden load impact and the self-reset control of the damping piston after buffering, solves the interference problem of the zero-field damping characteristic of the damper on the displacement control of the hydraulic cylinder, reduces the complexity of the buffer control strategy of the hydraulic cylinder, and finally realizes the function of continuous anti-impact and vibration reduction of buffer-unloading-buffer. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of the device according to an embodiment of the present invention;

[0026] Figure 2 is a partial part schematic diagram of the rotary electromagnetic unloading device according to an embodiment of the present invention;

[0027] Figure 3 is a schematic structural diagram of the porous sleeve connector according to an embodiment of the present invention;

[0028] Figure 4 This is a schematic structural diagram of the rotating flow deflector in the embodiment of the present invention;

[0029] Figure 5 This is a flowchart for implementing the control method of the embodiment of the present invention.

[0030] Wherein: 1. Lower end cover; 2. Spring at the lower end; 3. Damper piston at the lower end; 4. Push rod; 5. Rotating flow deflector at the lower end; 6. Chip permanent magnet; 7. Porous sleeve connector; 8. Nut; 9. Piston; 10. Piston rod; 11. Porous sleeve connector; 12. Rotating flow deflector at the upper end; 13. Stop piece; 14. Damper piston at the upper end; 15. Spring at the upper end; 16. Upper end cover; 17. Damper sleeve; 18. Inner flow path connector at the upper end; 19. Outer cylinder; 20. Inner cylinder; 21. Coil winding; 22. Rubber ring; 23. Inner flow path connector at the lower end; 24. Magnetic attraction winding; 25. Hydraulic cavity; 26. Damper cavity; 27. Hydrodynamic cavity; 28. Spring cavity. Detailed implementation manners

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0033] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary implementation manners according to the present application. As used herein, unless otherwise clearly specified in the context, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0034] The present invention provides a novel damping self-resetting hydraulic drive unit. Referring to Figures 1-4 as shown, it includes double-layer hydraulic cylinders 8 - 10, 19 - 20; rotary electromagnetic unloading devices 4 - 7, 11 - 14, 24; hydrodynamic damping devices 1 - 3, 14 - 17, 21.

[0035] Specifically, the double-layer hydraulic cylinder includes an inner cylinder barrel 20, an outer cylinder barrel 19, a piston 9, a piston rod 10, and two inner flow channel connectors 18 and 23. A plurality of coil grooves are provided on the outer side of the inner cylinder barrel 19. Rubber rings 22 are provided on the left and right sides of each coil groove. The rubber rings 22 are arranged in magnetic isolation grooves to prevent the magnetic fields of adjacent two coil windings from closing. The inner cavity of the inner cylinder barrel 19 is a hydraulic cavity 25, and the gap formed between the inner and outer cylinder barrels is defined as a damping cavity 26. The piston 9 divides the hydraulic cavity 25 into upper and lower parts, and the two inner flow channel connectors 18 and 23 are respectively communicated with the upper and lower parts of the hydraulic cavity 25.

[0036] The rotary electromagnetic unloading device includes two porous sleeve connectors 7 and 11, two rotary guide vanes 5 and 12, and two magnetic attraction windings (the structure is as Figure 2 shown by the reference numeral 24 in the figure). As Figure 1 、 2 shown, the two porous sleeve connectors are respectively nested at the upper and lower ends of the inner cylinder barrel. The rotary guide vanes are embedded on the bottom plates inside the porous sleeve connectors. The rotary guide vanes are annular structures with central through holes. Circumferentially distributed round holes are correspondingly formed on the bottom plate of the porous sleeve connector 11 and the annular part of the rotary guide vane 12. The interval between the round holes should be greater than the diameter of the round holes. The magnetic attraction winding 24 is embedded in the middle of the bottom plate of the porous sleeve connector. A plurality of sheet permanent magnets 6 are circumferentially embedded in the inner circle of the annular part of the rotary guide vane 12, and round holes identical to those of the porous sleeve connector 7 are provided at the outer ring. The positive and negative voltages of the magnetic attraction winding drive the rotary guide vane to rotate left and right, realizing the on-off of the flow direction of the hydraulic oil. The fixed position of the magnetic attraction coil determines its rotation angle.

[0037] The hydrodynamic damping device includes a plurality of coil windings 21, two damping pistons 3 and 14, two damping sleeves 17, two springs 2 and 15, an upper end cover 16 and a lower end cover 1. The plurality of coil windings 21 are respectively wound in the coil grooves on the outer wall of the inner cylinder. After being energized, the magnetorheological fluid flowing through the damping chamber 26 generates a damping force. The two damping sleeves are respectively nested at the upper end of the upper porous sleeve connector and the lower end of the lower porous sleeve connector. The upper end cover is installed at the upper end of the upper damping piston, and the lower end cover is installed at the lower end of the lower damping piston. The two springs are respectively installed between the damping piston and the upper end cover or the lower end cover. The damping piston 3 can axially move in the damping sleeve and divides the inner chamber of the damping sleeve 17 into a hydrodynamic chamber 27 and a spring chamber 28. The hydraulic oil in the hydraulic chamber 25 can flow into the hydrodynamic chamber 27 through the conduction state of the porous sleeve connector 7. The high-pressure oil in the hydrodynamic chamber pushes the damping piston 3 to move, so that the magnetorheological fluid in the spring chamber 28 flows through the damping chamber 26 to the spring chamber at the other end of the hydraulic drive unit, and at the same time pushes the symmetric damping piston 14 to move in the same direction. At this time, the magnetorheological fluid flowing through the damping chamber 26 generates a shear damping force due to the magnetorheological effect, thereby hindering the impact force of the high-pressure oil and achieving the effect of buffering and vibration reduction. The compression and self-resetting functions are realized by converting the pressure difference between both ends of the piston 9, and the upper and lower end covers are both provided with return grooves for conducting the spring chamber 28 and the damping chamber 26.

[0038] Referring to Figure 2 、 3 As shown in FIGS. 4, in this embodiment, a circular slide rail is provided in the porous sleeve connector 11, and a rotating deflector with a circular hole can rotate in the circular slide rail. When the magnetic attraction winding 24 is energized in the forward direction, the circular hole of the porous sleeve connector 11 is aligned with the circular hole of the rotating deflector 12, and the hydraulic oil is in a conducting state. When the magnetic attraction winding 24 is energized in the reverse direction, the circular hole of the porous sleeve connector is offset from the circular hole of the rotating deflector, and the hydraulic oil is in a disconnected state.

[0039] In this embodiment, while the damping piston 3 pushes the magnetorheological fluid to flow through the damping chamber 26, the spring 2 is compressed and the spring stores energy. When the pressure in the hydraulic chamber decreases, the compressed spring pushes the damping piston to reset, and the magnetorheological fluid flows in the reverse direction. The damping chamber 26 generates the required damping force during operation. When the spring 2 resets, the current of the coil winding 21 is turned off, and at this time, no damping force is generated in the damping chamber.

[0040] In this embodiment, connection holes are provided on the same side wall at both ends of the outer cylinder 19, and oil guiding holes are correspondingly provided on the inner cylinder 20. The connection holes and the oil guiding holes are concentric. The inner flow path connector passes through the connection holes and is communicated with the oil guiding holes on the inner cylinder, so that the hydraulic oil flows into the hydraulic chamber through the oil guiding holes on the inner cylinder.

[0041] In this embodiment, the magnetic attraction windings 24 are circumferentially distributed around the center of the porous sleeve connector and are fixed on the bottom plate of the porous sleeve connector 11 through the guide grooves. Their fixed positions play a role in restricting the positions of the rotary flow guide vanes. When energized, a magnetic field can be generated, and the attraction or repulsion of the permanent magnet sheet 6 is realized through the magnetic fields generated by positive and negative voltages.

[0042] Working principle

[0043] In this embodiment, when the piston rod 10 of the hydraulic damping drive unit moves upward, a downward variable load impact suddenly acts on the piston rod 10. The piston rod 10 drives the piston 9 to move downward, thereby compressing the hydraulic oil to generate a relatively high oil pressure. To prevent the pressure impact from reacting on the entire hydraulic system, the oil holes 18 and 23 at both ends of the drive unit are instantaneously closed. At this time, the rotary flow guide vanes 5 and 12 are conducted, and the hydraulic oil enters the hydrodynamic chamber 27 and then pushes the damping piston 3 to move downward, so that the magnetorheological fluid at the other end of the damping piston 3 flows into the upper spring chamber through the damping chamber 26, thereby pushing the upper damping piston 14 to move downward. The oil in the upper hydrodynamic chamber flows into the upper part of the piston through the rotary electromagnetic unloading device. The coil winding 21 is energized, and the magnetorheological fluid generates the required damping force under the action of the magnetic field. The lower spring 3 is compressed and the upper spring 15 is stretched to store energy. When the pressure impact disappears, the rotary flow guide vanes 5 and 12 are closed, blocking the up-and-down flow of the hydraulic oil. The coil winding 21 is powered off. When the oil pressure at the upper end of the piston is greater than or equal to the oil pressure at the lower end, the rotary flow guide vanes 5 and 12 are conducted again. At this time, the two groups of springs drive the damping pistons 3 and 14 to move upward. The lower hydrodynamic chamber discharges the hydraulic oil, and the upper hydrodynamic chamber sucks in the hydraulic oil. After the piston returns to its original position, the rotary flow guide vanes 5 and 12 are closed, waiting for the next impact.

[0044] As Figure 5 shown, this embodiment also provides a control method for the above-mentioned damping self-resetting hydraulic drive unit, including:

[0045] Step 1: Connect the wiring terminals of the coil winding 21 and the magnetic attraction winding 24 to the controller in sequence. A displacement sensor is installed outside the piston rod 10. The oil ports 18 and 23 at the upper and lower ends of the hydraulic drive unit are connected to the hydraulic pump through oil pipes. It is set that when the oil pressure at the lower end is greater than the pressure at the upper end, Δ>0; otherwise, Δ<0; when the oil pressure at the lower end is equal to the pressure at the upper end, Δ = 0.

[0046] Step 2: The magnetic attraction winding 24 is energized in the reverse direction, the porous sleeve connectors 7 and 11 are in the blocking state, and the hydraulic oil enters the hydraulic chamber 25 from the lower oil port, thereby pushing the piston 9 and the piston rod 10 upward. When the top of the piston rod 10 is impacted by a sudden downward load, while the piston rod 10 moves downward, the impact force it receives is transmitted to the hydraulic chamber 26 at the lower end of the piston through the piston 9, and the pressure in the lower oil chamber suddenly increases, resulting in a larger pressure difference between the upper and lower oil chambers of the piston 9. At this time, the porous sleeve connectors 7 and 11 at both ends are applied with a positive voltage to quickly conduct the hydraulic chamber 25 and the hydrodynamic chamber 27, so that the hydraulic oil in the hydrodynamic chamber is pushed by the high pressure to move the damping piston 3 downward, thereby driving the magnetorheological fluid in the spring chamber 28 to flow through the damping chamber 27 and then into the symmetric end spring chamber, pushing the symmetric end spring 15 downward. At this time, the coil winding 21 is energized, and the pressure in the lower oil chamber of the piston is adjusted through the buffer control algorithm to reduce the directional impact of the oil fluid on the pump source.

[0047] Step 3: When the sudden load disappears, the magnetic attraction winding 24 is applied with a reverse voltage, the porous sleeve connectors 7 and 11 are closed, and it is recorded that the lower damping spring device 2 - 3 is in the compressed state and the upper damping spring device 14 - 15 is in the stretched state. The pressure difference signal at both ends of the hydraulic cylinder is collected. When Δ < 0 or Δ = 0, the magnetic attraction winding 24 is applied with a positive voltage, the porous sleeve connectors 7 and 11 are conducted, and the compression springs 3 and 15 at both ends push the damping pistons 3 and 14 upward. The hydraulic oil in the cavity is discharged from the lower end through the porous sleeve connector 7, and a part of the hydraulic oil in the hydraulic chamber is sucked into the upper end through the porous sleeve connector 11. After the damping pistons 3 and 14 are reset, the magnetic attraction winding 24 is energized in the reverse direction, the porous sleeve connectors 7 and 11 are blocked, and it enters the impact buffer waiting state.

[0048] Step 4: During the displacement accuracy control process, when a larger oil pressure is applied, the piston 9 is impacted by a larger oil fluid, and the piston rod 10 generates a displacement fluctuation error. At this time, the porous sleeve connectors 7 and 11 are conducted, and the high-pressure oil fluid in the hydraulic chamber flows into the hydrodynamic chamber to achieve unloading. At the same time, the required damping force is generated through the buffer control algorithm to slow down the hydraulic shock, thereby improving the displacement fluctuation error. Finally, the self-resetting function is switched by judging the pressure difference at both ends.

[0049] Preferably, in Step 1, the number of the coil windings 21 is more than two, the winding directions are the same, and they are axially arranged. In order to increase the magnetic field strength in the damping chamber gap, the positive and negative connection methods of the connection terminals of adjacent coil windings 21 are opposite.

[0050] Preferably, in Step 1, when impacted by a sudden load, in order to ensure the control accuracy and prevent the reverse impact of the oil fluid on the pump source, at this time, the oil inlets 18 and 23 at both the upper and lower ends of the hydraulic pump are in the closed state, and all the oil fluid circulation is carried out in the inner and outer cavities.

[0051] Preferably, in Steps 2 and 3, when the direction of the mutation load is upward, after buffering, it is recorded that the upper damping spring devices 2-3 and 14-15 are in a compressed state. When Δ>0 or Δ = 0, the magnetic attraction winding is energized in the forward direction, the damping piston 3 resets, the magnetic attraction winding 24 is energized in the reverse direction, and the porous sleeve connectors 7 and 11 are blocked, entering the impact buffering waiting state.

[0052] Preferably, during the process where the porous sleeve connectors 7 and 11 are conducting and cooperating with the control algorithm for buffering, the judgment basis is the displacement error of the hydraulic cylinder during operation. Within the allowable range of the displacement error, the magnitude of the current flowing into the coil winding 21 is continuously adjusted to improve the impact buffering effect.

[0053] Principle of the control method

[0054] In this embodiment, when the piston rod 10 of the hydraulic damping drive unit moves upward, a downward variable load impact suddenly acts on the piston rod 10. The displacement data of the piston rod 10 is collected. The piston rod 10 transmits the impact force to the hydraulic oil at the lower end of the piston 9. At this time, the control valves at both ends of the hydraulic drive unit are closed, the magnetic attraction winding 24 is energized in the forward direction, and the rotating guide vanes 5 and 12 are conducting. The high-pressure oil flows into the hydraulic power chamber 27 to push the damping pistons 3 and 14 downward, and the springs 2 and 15 store energy. The output current magnitude is controlled by using the displacement signal and the damping control algorithm for the coil winding 21 to further control the anti-impact and vibration reduction effect. When the displacement error reaches stability, the magnetic attraction winding 24 is energized in the reverse direction, the rotating guide vanes 5 and 12 are closed, the control valves at both ends of the hydraulic drive unit are opened and continue to work. The pressure difference between both ends of the piston 9 is detected. When the pressure at the upper end of the piston 9 is greater than or equal to the pressure at the lower end, the magnetic attraction winding 24 is energized in the forward direction, and the rotating guide vanes 5 and 12 are conducting again. Under the condition of ensuring a small displacement disturbance, the energy storage springs 2 and 15 push the damping pistons 14 and 3 so that the upper hydraulic power chamber sucks in hydraulic oil, and the lower hydraulic power chamber discharges the excess hydraulic oil. After the damping pistons 3 and 14 are reset, the magnetic attraction winding 24 is energized in the reverse direction, the rotating guide vanes 5 and 12 are closed, and the displacement data of the piston rod is collected again, entering the impact buffering waiting state.

[0055] The above is only a preferred embodiment of the present invention, and it is not a limitation of the present invention in other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A damping self-resetting hydraulic drive unit, characterized in that, It includes a double-layer hydraulic cylinder, a rotary electromagnetic unloading device and a hydrodynamic damping device. The double-layer hydraulic cylinder includes an inner cylinder barrel, an outer cylinder barrel, a piston, a piston rod and two internal flow channel connectors. A plurality of coil grooves are provided on the outer side of the inner cylinder barrel. Magnetic isolation grooves are provided on both sides of each coil groove, and rubber rings are provided in the magnetic isolation grooves to prevent the magnetic field of the coil winding from closing on the inner cylinder barrel. The inner cavity of the inner cylinder barrel is a hydraulic cavity, and the gap formed between the inner and outer cylinder barrels is a damping cavity. The piston divides the hydraulic cavity into upper and lower parts, and the two internal flow channel connectors are respectively communicated with the upper and lower parts of the hydraulic cavity; The rotary electromagnetic unloading device includes two porous sleeve connectors, two rotary guide vanes and two magnetic attraction windings. The two porous sleeve connectors are respectively nested at the upper and lower ends of the inner cylinder barrel. The rotary guide vane is embedded on the bottom plate in the porous sleeve connector. The rotary guide vane is an annular structure with a central through hole. Circumferentially distributed round holes are correspondingly provided on the bottom plate of the porous sleeve connector and the annular part of the rotary guide vane, and the interval between the round holes is greater than the diameter of the round holes. A magnetic attraction winding is embedded in the middle of the bottom plate of the porous sleeve connector. A plurality of chip permanent magnets are embedded along the circumference of the inner ring of the annular part of the rotary guide vane. By the positive and negative voltages of the magnetic attraction winding, the rotary guide vane can be driven to rotate left and right, so as to realize the on-off of the flow direction of the hydraulic oil. The fixed position of the magnetic attraction winding determines its rotation angle; The hydrodynamic damping device includes a plurality of coil windings, two damping pistons, two damping sleeves, two springs, an upper end cover and a lower end cover. The plurality of coil windings are respectively wound in the corresponding coil grooves on the outer wall of the inner cylinder barrel. After being energized, the magnetorheological fluid flowing through the damping cavity generates a damping force. The two damping sleeves are respectively nested at the upper end of the upper porous sleeve connector and the lower end of the lower porous sleeve connector. The upper end cover is installed at the upper end of the upper damping piston, and the lower end cover is installed at the lower end of the lower damping piston. The two springs are respectively installed between the damping piston and the upper end cover or the lower end cover. The damping piston axially moves in the damping sleeve and divides the inner chamber of the damping sleeve into a hydrodynamic chamber and a spring chamber. The hydraulic oil in the hydraulic cavity can flow into the hydrodynamic chamber through the conduction state of the porous sleeve connector. The high-pressure oil in the hydrodynamic chamber pushes the damping piston to move, so that the magnetorheological fluid in the spring chamber flows through the damping cavity to the spring chamber at the other end of the hydraulic drive unit, and at the same time pushes the damping piston at the other end to move in the same direction. At this time, the magnetorheological fluid flowing through the damping cavity generates a shear damping force due to the magnetorheological effect, thereby hindering the impact force of the high-pressure oil and playing a role in buffering and vibration reduction. The self-resetting function of the compression and damping piston is realized by using the pressure difference conversion between the two ends of the piston. Return grooves for conducting the spring chamber and the damping cavity are provided on both the upper and lower end covers.

2. The damped self-resetting hydraulic drive unit according to claim 1, wherein, A circular slide rail is provided inside the porous sleeve connector. The rotating deflector with a circular hole can rotate within the circular slide rail. When the magnetic attraction winding is energized in the forward direction, the circular hole of the porous sleeve connector is aligned with the circular hole of the rotating deflector, and the hydraulic oil is in a conducting state. When the magnetic attraction winding is energized in the reverse direction, the circular hole of the porous sleeve connector is offset from the circular hole of the rotating deflector, and the hydraulic oil is in a disconnected state.

3. A damped self-resetting hydraulic drive unit according to claim 1, characterized in that, The damping piston pushes the magnetorheological fluid to flow through the damping chamber while compressing the spring, and the spring stores energy. When the pressure difference between the two ends of the piston in the hydraulic chamber decreases, the compressed spring pushes the damping piston to reset, and the magnetorheological fluid flows in the reverse direction. The damping chamber generates the required damping force during operation. When the spring resets, the current of the coil winding is turned off, and no damping force is generated at this time.

4. A damped self-resetting hydraulic drive unit according to claim 1, wherein Connection holes are provided on the same side wall at both ends of the outer cylinder barrel, and oil guiding holes are correspondingly provided on the inner cylinder barrel. The connection holes and the circular holes are guaranteed to be concentric. The inner flow path connector passes through the connection holes and is connected to the oil guiding holes on the inner cylinder barrel, so that the hydraulic oil flows into the hydraulic chamber through the oil guiding holes on the inner cylinder barrel.

5. A damping self-resetting hydraulic drive unit according to claim 1, characterized in that, The magnetic attraction winding is circumferentially distributed around the center of the porous sleeve connector and is fixed on the bottom plate of the porous sleeve connector through a guide groove. Its fixed position also serves to limit the position of the rotating deflector. When energized, it can generate a magnetic field, and the adsorption or repulsion of the permanent magnet sheet is realized through the magnetic fields generated by positive and negative voltages.

6. A control method for a damping self-resetting hydraulic drive unit according to any one of claims 1-5, characterized in that It includes the following steps: Step 1: Connect the wiring terminals of the coil winding and the magnetic attraction winding to the controller in sequence. A displacement sensor is installed outside the piston rod. The upper and lower oil ports of the hydraulic drive unit are connected to the hydraulic servo valve through oil pipes. It is set that when the oil pressure at the lower end is greater than that at the upper end, Δ>0; conversely, Δ<0; when the oil pressure at the lower end is equal to that at the upper end, Δ = 0. Step 2: The magnetic attraction winding is energized in the reverse direction, and the porous sleeve connector is in a blocking state. The hydraulic oil enters the hydraulic chamber from the lower oil port, thereby pushing the piston and the piston rod to move upward. When the top of the piston rod is impacted by a sudden downward load, the piston rod moves downward while transmitting the impact force received to the hydraulic chamber at the lower end of the piston through the piston. The pressure in the lower oil chamber suddenly increases, resulting in a larger pressure difference between the upper and lower oil chambers of the piston. At this time, a positive voltage is applied to the porous sleeve connectors at both ends, and the hydraulic chamber and the hydrodynamic chamber are quickly connected. Then, the high pressure causes the hydraulic oil in the hydrodynamic chamber to push the piston downward, driving the magnetorheological fluid in the spring chamber to flow through the damping chamber, and then flowing back into the symmetric end spring chamber through the end cover return groove, and pushing the symmetric end spring downward. At this time, the coil winding is energized, and the input current of the coil winding is adjusted to control the damping force generated by the damping chamber, thereby adjusting the pressure in the lower oil chamber of the piston and reducing the impact of the oil on the hydraulic servo system. Step 3: When the mutation load disappears, a reverse voltage is applied to the magnetic attraction winding, the porous sleeve connector closes, and it is recorded that the spring at the lower end is in a compressed state and the spring at the upper end is in a stretched state. The differential pressure signal at both ends of the hydraulic cylinder is collected. When Δ < 0 or Δ = 0, a positive voltage is applied to the magnetic attraction winding, the porous sleeve connector conducts, and the compression springs at both ends push the piston upward. The hydraulic oil in the cavity is discharged through the porous sleeve connector at the lower end, and a part of the hydraulic oil in the hydraulic cavity is sucked at the upper end. After the piston resets, the magnetic attraction winding is energized in the reverse direction, the porous sleeve connector is blocked, and it enters the impact buffering waiting state; Step 4: During the displacement accuracy control process, when a relatively large oil pressure is applied, the piston is subjected to a large oil impact, and the piston rod generates a displacement fluctuation error. At this time, the porous sleeve connector conducts, and the high-pressure oil in the hydraulic cavity flows into the hydrodynamic cavity to achieve unloading. At the same time, the required damping force is generated to slow down the hydraulic impact, thereby improving the displacement fluctuation error. Finally, the self-resetting function is switched by judging the differential pressure at both ends.

7. A control method for a damping self-resetting hydraulic drive unit according to claim 6, characterized in that, In Step 1, the number of coil windings is greater than two, the winding directions are the same, and they are axially arranged. In order to increase the magnetic field strength in the damping cavity gap, the positive and negative connection methods of the connection terminals of adjacent coil windings are opposite.

8. The control method of a damping self-resetting hydraulic drive unit according to claim 6, characterized in that, In Step 1, when subjected to a sudden load impact, in order to ensure the control accuracy and prevent the reverse impact of the oil on the hydraulic servo system, the servo valve of the hydraulic cylinder is in the closed state at this time, and all oil circulation is carried out in the inner and outer cavities.

9. The control method of a damping self-resetting hydraulic drive unit according to claim 6, characterized in that In Steps 2 and 3, when the direction of the mutation load is upward, after buffering, it is recorded that the spring at the upper end is in a compressed state. When Δ > 0 or Δ < 0, the magnetic attraction winding is energized in the forward direction, the piston resets, the magnetic attraction winding is energized in the reverse direction, the porous sleeve connector is blocked, and it enters the impact buffering waiting state.

10. The control method of a damping self-resetting hydraulic drive unit according to claim 6, characterized in that, During the process of the porous sleeve connector conducting and buffering, the judgment basis is the displacement error of the hydraulic cylinder during the working process; within the allowable range of the displacement error, the magnitude of the current applied to the coil winding is continuously adjusted to improve the impact buffering effect.

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