High-load electric drive hydraulic control cylinder and driving method thereof

Abstract

This invention discloses a high-load electro-hydraulic control cylinder and its driving method, including a cylinder body, a piston, a piston rod, and a driving device. The cylinder body has a first oil chamber, and the piston rod has a cavity. The driving device extends to the piston rod cavity via a driving rod, and a driving rod piston is located at the front end of the driving rod, forming a second oil chamber and a driving rod cavity. A hydraulic drive assembly is integrated inside the piston, and the hydraulic drive assembly is connected to the first and second oil chambers via oil passages. The driving rod has radially arranged keyed teeth that engage with the keyed teeth of the meshing holes in the hydraulic drive assembly. The first and second oil chambers have equal annular cross-sectional areas, solving the problem of hydraulic control under constant velocity conditions. A pressure regulating oil circuit is provided at the piston rod end for pressure regulation. The driving rod piston is non-fixedly connected to the driving rod via a T-slot, avoiding seal wear. This invention has advantages such as high energy efficiency, strong dynamic response, no leakage, and resistance to special environments. Through deep electromechanical-hydraulic synergy, it achieves a comprehensive improvement in energy efficiency, precision, and reliability.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic component technology, specifically a high-load electro-hydraulic control cylinder and its driving method. Background Technology

[0002] In industrial engineering, traditional linear displacement driven hydraulic cylinders, compared with electric cylinders and pneumatic cylinders, have the characteristics of high energy density and stable drive. However, hydraulic cylinders require specialized control components and hydraulic systems for control, and the connection between the two requires complex pipelines, resulting in high leakage risk, high failure rate, large size, and significant energy loss in electrical and hydraulic transmission. Moreover, ordinary hydraulic cylinders are inefficient, exhibit delays in dynamic response during high-speed reciprocating operation, and are insufficiently adaptable to complex working conditions. Fixed throttling speed control circuits cannot match the changing load requirements in real time, failing to meet the many demanding requirements of current intelligent control fields. Existing electro-hydraulic actuators and electric cylinders basically achieve this by carrying a certain volume on the cylinder end. Electro-hydraulic actuators are implemented using motors, transmission components, or hydraulic power units. Because of the asymmetrical volume structure of the rod-side and rodless chambers, electro-hydraulic actuators require a certain amount of space in the oil tank, inevitably increasing their size. Therefore, electro-hydraulic actuators and electric cylinders still rely on traditional hydraulic drive control structures and methods. Pneumatic cylinders are used for light-load conditions, but the compressibility of gas is difficult to control. With technological advancements and the development of new energy and energy storage technologies, more and more equipment is adopting electric drives, such as electric cylinders in linear drives. However, electric cylinders suffer from low driving force, easily damaged precision lead screws, and high costs, failing to meet high-load requirements. Therefore, a linear drive technology and device integrating electric and hydraulic systems is needed to solve these problems. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a high-load electro-hydraulic cylinder and its driving method, comprising: a cylinder body, a piston and a piston rod disposed within the cylinder body, a first oil chamber formed between the cylinder body and the piston rod, a driving device disposed at one end of the rodless chamber of the cylinder body, a driving rod disposed within the cylinder body, and an output shaft of the driving device fixedly connected to the tail end of the driving rod; a cavity is provided within the piston rod, the driving rod extends from the output shaft end of the driving device into the piston rod cavity, a driving rod piston is mounted at the front end of the driving rod, a second oil chamber is formed between the front end face of the driving rod piston and the piston rod, and the rear end face of the driving rod piston is connected to the piston rod... A drive rod cavity is formed between the rods; the piston has a cavity inside for mounting the hydraulic drive assembly, and the piston body has an oil passage for connecting the hydraulic drive assembly and the first oil chamber. The piston body and piston rod have interlocking oil passages to connect the hydraulic drive assembly and the second oil chamber; the drive rod has axially extending key teeth on its radial circumferential surface; the hydraulic drive assembly includes a transmission input component that is pulverizedly connected to the drive rod, the transmission input component has a meshing hole, and the inner wall of the meshing hole has axially arranged key teeth. The key teeth of the drive rod mesh with the key teeth of the meshing hole of the transmission input component.

[0004] Preferably, the hydraulic drive assembly includes an internal gear, an external gear, and an oil separator, with the external gear serving as the transmission input.

[0005] Preferably, the hydraulic drive assembly includes a swashplate support, a swashplate, a piston assembly, a straight plate, a distributor plate, a ball joint, and pressure plates on both sides; the swashplate and the straight plate serve as transmission input components, and the swashplate support, piston assembly, straight plate, distributor plate, ball joint, and pressure plates on both sides are all provided with through holes for the drive rod to pass through.

[0006] Preferably, the piston includes a ring body and a front cover and a rear cover disposed on both sides of the ring body. The ring body is axially connected to the cylinder bore, and the front cover is fixedly connected to the piston rod. The front cover is provided with a connecting oil passage. The ring body is provided with an oil passage one and an oil passage two. The piston rod sidewall is provided with a second oil chamber passage that connects to the second oil chamber. Oil passage one connects the hydraulic drive assembly and the first oil chamber. One end of oil passage two is connected to the drive hydraulic assembly, and the other end is connected to the second oil chamber passage.

[0007] Preferably, the piston includes a housing and a housing cover mounted behind the housing. The housing is fitted with a cylinder bore shaft. The housing is provided with an oil passage one and an oil passage two. The oil passage one connects to the first oil chamber, and the oil passage two connects to the passage of the second oil chamber.

[0008] Preferably, the area of ​​the annular cross-section A of the first oil cavity is the same as the area of ​​the cross-section B of the second oil cavity.

[0009] Preferably, a through hole is provided at the bottom of the cylinder block, the output shaft of the drive device is connected to the drive rod, and a limiting groove is provided on the side near the cylinder block. A convex ring adapted to the limiting groove is fixedly provided at the end of the drive rod. The convex ring and the limiting groove can counteract the axial force of the drive rod.

[0010] Preferably, a T-shaped head is provided at the end of the drive rod, and a T-shaped groove adapted to the T-shaped head at the end of the drive rod is provided inside the drive rod piston, so that the drive rod piston does not rotate with the drive rod and avoids wear of the seal.

[0011] Preferably, a lubrication oil passage is provided on the outer edge of the drive rod piston, and two sealing rings are provided on both sides of the lubrication oil passage. The lubrication oil passage is connected to the T-groove inside the drive rod piston.

[0012] Preferably, a pressure regulating oil circuit is provided at the end of the piston rod, which connects the first oil chamber and the second oil chamber. A bridge-type overflow circuit is provided on the pressure regulating oil circuit, which includes one-way valve one, one-way valve two, one-way valve three, one-way valve four and an overflow valve. The oil in the first oil chamber enters the pressure regulating oil circuit and can enter the second oil chamber after passing through one-way valve one, overflow valve and one-way valve four. The oil in the second oil chamber enters the first oil chamber after passing through one-way valve two, overflow valve and one-way valve three.

[0013] Preferably, the drive unit can be a servo motor, a hydraulic motor, an engine with a gearbox, or any device capable of providing forward and reverse driving force.

[0014] Preferably, the hydraulic drive assembly can be a hydraulic motor, a hydraulic pump, or a cycloidal motor, wherein the hydraulic motor includes a gear motor or a piston motor, and the hydraulic pump includes a gear pump or a piston pump.

[0015] Preferably, the external gear includes a gear body and an internal gear sleeve at the center of the gear body. The internal gear sleeve has an axial through hole at its center, and a key tooth adapted to the drive rod is provided in the axial through hole.

[0016] Preferably, the cylinder block also includes a temperature control circuit, which includes a first passage inside the cylinder bottom and a second passage inside the drive rod. The first passage and the second passage are connected, and a sealing ring is provided at the connection between the first passage and the second passage. The cooling medium enters the second passage in the drive rod from the first passage, and after cooling circulation, it is discharged from the first passage again.

[0017] Preferably, passage two connects to the drive rod cavity, and a gap hole is provided between the drive rod and the transmission input component. After the cooling medium enters the drive rod cavity through passage one and passage two, it enters the rodless cavity through the gap hole and is discharged through the through hole on the side wall of the rodless cavity.

[0018] Preferably, an oil port is provided on the side wall of the first oil cavity.

[0019] Based on the above technical solution, the present invention also provides a driving method for a high-load electro-hydraulic cylinder. When the piston rod is about to extend out of the cylinder, the driving device is activated to drive the driving rod to start rotating. The driving rod provides rotational driving force to the hydraulic drive assembly. During the operation of the hydraulic drive assembly, the oil enters the first oil passage from the first oil chamber. The hydraulic drive assembly distributes the oil in the first oil passage to the second oil passage through the second oil passage. The pressure inside the second oil chamber increases, causing the volume of the second oil chamber to expand. At the same time, the volume of the first oil chamber decreases, and the piston begins to move along the overall axial direction of the driving rod, pushing the piston rod to extend. When the piston rod is about to retract into the cylinder, the driving device rotates in the opposite direction, driving the hydraulic drive assembly to distribute the oil in the opposite direction. The oil is distributed from the second oil chamber and the second oil passage to the first oil passage through the first oil chamber. The pressure inside the first oil chamber increases, causing the volume of the first oil chamber to increase while the volume of the second oil chamber decreases. The oil pushes the piston to move axially backward along the driving rod, causing the piston rod to retract into the cylinder.

[0020] Preferably, the cross-sectional area A of the first oil chamber is the same as the cross-sectional area B of the second oil chamber. During the operation of the hydraulic drive assembly, the volume changes of the first and second oil chambers are the same. Under rated load and without external interference, the displacement and feed displacement can be estimated by the number of motor rotations.

[0021] Preferably, when the pressure difference between the second oil chamber and the first oil chamber is too large, the oil in the second oil chamber can enter the first oil chamber through the pressure regulating oil circuit into the bridge overflow circuit via check valve 2, overflow valve and check valve 3, or the oil in the first oil chamber can enter the second oil chamber through the pressure regulating oil circuit into the bridge overflow circuit via check valve 1, overflow valve and check valve 4, thereby achieving pressure-safe overflow.

[0022] The present invention has the following beneficial effects: The electro-hydraulic cylinder with built-in power integrates a motor, power source, and hydraulic control circuit mechanism. Compared with hydraulic cylinders controlled by traditional hydraulic systems, it improves energy efficiency, dynamic response capability, adaptability to complex working conditions, and safety. Its internal circulation system eliminates external pollution and leakage risks, and eliminates the need for pipelines and complex control components. It can be used in special environments such as deep sea, deep space, and underground. Compared with electric cylinders, it has a simpler shape and significantly better push-pull driving capability under the same volume than electric cylinders driven by lead screws. During extension and retraction, the effective area A of the first oil chamber is equal to the effective area B of the second oil chamber, and both areas are the same, similar to the rod-type and rodless chambers of ordinary hydraulic cylinders. Compared to other methods with area differences, this method solves the problem of hydraulic control under constant speed conditions. Under rated load and without external interference, the displacement and feed displacement can be estimated by the number of motor rotations, eliminating the need for a displacement sensor. A pressure protection circuit connecting the two working oil chambers is set at the piston rod end, and pressure regulation can be easily achieved by adjusting the overflow valve. The drive rod piston is not fixedly connected to the spline shaft, and the drive rod piston is not rotated, ensuring sealing performance and extending service life. The cylinder body is equipped with a temperature control circuit. During high-frequency operation, external coolant can be passively introduced into the non-working chambers at both ends of the spline shaft movement as the piston body reciprocates, achieving overall heat control of the high-load electro-hydraulic cylinder.

[0023] The high-load electro-hydraulic control cylinder has a compact internal component structure, convenient connection, stronger overall cylinder structure, and stable drive shaft force, which greatly reduces the failure rate inside the cylinder. Through deep electromechanical-hydraulic synergy, it achieves a comprehensive improvement in energy efficiency, precision, and reliability. Attached Figure Description

[0024] Figure 1 This is a cross-sectional view of the overall structure of the present invention; Figure 2 This is a cross-sectional view of the overall structure of the present invention in another state; Figure 3 This is a cross-sectional view of the overall structure of the second embodiment of the present invention; Figure 4 This is a cross-sectional view of the overall structure of the piston part of the present invention; Figure 5 This is a cross-sectional view of the overall structure of the piston section according to the second embodiment of the present invention; Figure 6 This is a cross-sectional view of the internal structure of the gear-type power source of the present invention; Figure 7 This is a schematic diagram of the overall structure of the drive rod of the present invention; Figure 8 This is a schematic diagram of the working principle of the oil system in this invention; Figure 9 This is a schematic cross-sectional view of the first oil cavity A region of the present invention; Figure 10 This is a schematic cross-sectional view of region B of the second oil cavity in this invention; Figure 11 This is a cross-sectional view of the overall structure of the third embodiment of the present invention; Figure 12 yes Figure 11 Sectional view at CC; Figure 13 This is a schematic diagram of the cross-sectional structure of the power source of the present invention, which uses a gear motor. Figure 14 This is a schematic diagram illustrating the structural principle of the fluid replenishment mechanism in this invention.

[0025] in: 1-Cylinder block, 11-First oil chamber, 12-Oil port, 2-Piston, 21-Oil passage one, 22-Oil passage two, 3-Piston rod, 31-Second oil chamber, 32-Second oil chamber passage, 33-Drive rod cavity, 34-Drive rod piston, 35-Lubricating oil passage, 36-Pressure regulating oil passage, 37-Bridge overflow circuit, 371-Check valve one, 372-Check valve two, 373-Check valve three, 374-Check valve four, 375-Overflow valve. 38-Fluid replenishment mechanism, 381-End cap, 382-Isolation piston, 383-Air inlet connector, 384-Air chamber, 385-Fluid filling chamber, 386-Fluid replenishment passage. 4-Drive unit, 41-Drive rod, 511-Front cover, 512-Ring body, 513-Rear cover, 514-Internal gear, 515-External gear, 516-Oil separator block, 517-Connecting oil passage, 518-Internal gear sleeve, 521-Housing shell, 522-Housing shell rear cover, 523-Swashplate support, 524-Distributor plate, 525-Swashplate, 526-Straight plate, 527-Plunger assembly, 528-Ball joint, 529-Pressure plate, 6-Passage 1, 7-Passage 2, 8-Through hole, 9-Gap hole. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1: like Figure 1 As shown, the cylinder body 1 is cylindrical, and an annular guide sleeve is provided at the cylinder head of the cylinder body 1. An oil port 12 is provided on the side wall of the cylinder body 1 near the guide sleeve for injecting oil. A thread is provided at the cylinder head of the cylinder body 1, and the guide sleeve is installed inside the cylinder body 1 through the thread. A hole is opened at the center of the bottom of the cylinder body 1 for the output shaft of the drive device 4 to pass through. The drive device 4 is provided on the outside, and the piston 2 is provided inside the cylinder body 1.

[0028] like Figure 2 , Figure 3 As shown, the front end of piston 2 is fixedly connected to piston rod 3. Piston 2 is axially engaged with cylinder 1. A sealing ring is provided at the engagement point between piston 2 and cylinder 1. An axial through hole is provided in the middle of piston 2. Piston rod 3 extends out of cylinder 1 through guide sleeve. Piston rod 3 is connected to guide sleeve shaft hole. A sealing ring is provided in the inner hole of guide sleeve. A sealed first oil chamber 11 is formed between piston 2 and guide sleeve in cylinder 1. A cavity is provided inside piston rod 3.

[0029] The drive unit 4 is fixed to the center of the outer side of the cylinder bottom of the cylinder block 1 by bolts. The output shaft of the drive unit 4 is fixedly connected to the drive rod 41. The drive unit 4 can be a servo motor, a hydraulic motor, an engine with a gearbox, or any drive unit with a reversible output shaft. The drive rod 41 is a splined shaft. The connection between the drive rod 41 and the output shaft of the drive unit 4 is located in the center hole of the cylinder bottom of the cylinder block 1. A limiting groove is provided on the inner side of the center hole of the cylinder bottom. The diameter of the limiting groove is larger than the diameter of the center hole of the cylinder bottom, forming an annular surface. A convex ring adapted to the limiting groove is fixedly provided at the upper end of the drive rod 41. The convex ring can abut against the annular surface of the limiting groove and block the axial force of the drive rod 41 during the operation of the piston part 3. The drive rod 41 extends through the axial through hole in the middle of the piston 2 into the cavity inside the piston rod 3. The drive rod piston 34 is installed in the cavity inside the piston rod 3. A T-shaped head is provided at one end of the drive rod 41 and the drive rod piston 34. A T-shaped groove is provided inside the drive rod piston 34 to fit the T-shaped head at the end of the drive rod 41. The drive rod piston 34 is fastened to the end of the drive rod 41. The T-shaped groove inside the drive rod piston 34 can prevent the drive rod piston 34 from rotating with the drive rod 41, thus avoiding wear of the seal. The outer edge of the drive rod piston 34 is tightly fitted with the inner wall of the piston rod 3. Two sealing rings are provided on the outer edge of the drive rod piston 34. The inner end face of the drive rod piston 34 and the piston rod 3 form a drive rod cavity 33. A lubricating oil passage 35 is provided inside the drive rod piston 34. One end of the lubricating oil passage 35 is located between the two sealing rings of the drive rod piston 34, and the other end is connected to the T-groove of the drive rod piston 34. Thus, during the movement of the piston rod 3, when the second oil chamber 31 is filled with oil, the oil that leaks through the sealing ring on the drive rod piston 34 near the second oil chamber 31 can lubricate the connection between the drive rod 41 and the drive rod piston 34. The space between the drive rod piston 34 and the end of the piston rod 3 forms the second oil chamber 31. The side wall of the piston rod 3 is provided with a second oil chamber passage 32 and a pressure regulating oil passage 36. A bridge overflow circuit 37 is provided on the pressure regulating oil passage 36.

[0030] like Figure 4 As shown, piston 2 includes a front cover 511, an ring body 512, and a rear cover 513. The ring body 512 is provided with an oil passage 21 and an oil passage 22. The front cover 511 is bolted to the flange of piston rod 3 and has an internal connecting oil passage 517. The two ends of the connecting oil passage 517 are respectively connected to oil passage 22 and the second oil chamber passage 32. Figure 6As shown, the hydraulic drive assembly includes a side plate connected to the front cover 511 and the rear cover 513, an internal gear 514 and an external gear 515 between the side plates, and an oil separator 516 between the internal gear 514 and the external gear 515. Symmetrical oil passages are provided on both sides of the hydraulic drive assembly, with their ends connected to oil passage 1 21 and oil passage 22 respectively. An internal gear sleeve 518 is provided in the middle of the external gear 515, which can drive the external gear 515 to rotate. When the internal gear 514 and the external gear 515 rotate in the same direction, the gears gradually separate on the oil suction side, increasing the inter-tooth volume and creating a negative pressure. Liquid is drawn into the pump core and sealed between the tooth groove and the oil separator 516. As the gears rotate, the liquid moves along the pump cavity towards the oil discharge side. On the oil discharge side, the gears re-mesh, causing the sealing volume to decrease, and the liquid, after being squeezed, is output through the oil discharge port. Figure 7 As shown, the drive rod 41 is a splined shaft, and the internal gear sleeve 518 has an axial spline through hole at its center. The spline through hole is adapted to the spline of the drive rod 41, and can rotate by the drive rod 41. At the same time, it can reciprocate axially along the drive rod 41. The drive rod 41 can also be a single key shaft, and the keyway in the internal gear sleeve 518 can be a single keyway adapted to the single key shaft.

[0031] like Figure 8 As shown, the bridge-type overflow circuit 37 includes a check valve 371, a check valve 372, a check valve 373, a check valve 374, and an overflow valve 375. One end of the overflow valve 375 is connected to the check valves 371 and 372, and the other end of the overflow valve 375 is connected to the check valves 373 and 374. The inlet of the check valve 371 and the outlet of the check valve 373 are connected to the first oil chamber 11 through the pressure regulating oil circuit 36. The inlet of the check valve 372 and the outlet of the check valve 374 are connected to the second oil chamber 31 through the other end of the pressure regulating oil circuit 36. The oil in the first oil chamber 11 enters from the pressure regulating oil circuit 36, passes through the one-way valve 371, the overflow valve 375, the one-way valve 374 and the other end of the pressure regulating oil circuit 36 ​​to enter the second oil chamber 31. The oil in the second oil chamber 31 enters from the pressure regulating oil circuit 36, passes through the one-way valve 372, the overflow valve 375, the one-way valve 373 and the other end of the pressure regulating oil circuit 36 ​​to enter the first oil chamber 11.

[0032] like Figure 9 , Figure 10 As shown, the cross-sectional area A of the first oil chamber 11 is the same as the cross-sectional area B of the second oil chamber 31, A = A1 - A2, where A1 is the outer diameter of the first oil chamber 11 and A2 is the inner diameter of the first oil chamber 11. Since A and B have the same cross-sectional area, the volume change of the two oil chambers is the same during the oil distribution process. Compared with the area difference between the rod chamber and the rodless chamber of a conventional hydraulic cylinder, this solves many hydraulic control problems under constant speed conditions. Under rated load and without external interference, the displacement and feed displacement can be estimated by the number of motor rotations, eliminating the need for a displacement sensing device.

[0033] When Embodiment 1 is in operation, all chambers are filled with oil. During the extension operation, piston 2 is located at the bottom of cylinder 1. The drive device 4 is activated, and the drive device 4 drives the drive rod 41 to start rotating. The rotation of the drive rod 41 drives the hydraulic drive assembly to start operating. During the operation of the hydraulic drive assembly, oil enters oil passage 21 from the first oil chamber 11. The hydraulic drive assembly controls the oil to enter the second oil chamber 31 through oil passage 22, connecting oil passage 517 and the second oil chamber passage 32 connected to it. At this time, piston 2 begins to move along the overall axial direction of drive rod 41, pushing piston rod 32 to extend.

[0034] When the piston rod 3 is to retract into the cylinder 1, the drive device 4 rotates in the opposite direction, driving the hydraulic drive assembly to distribute the oil in the opposite direction. The oil is distributed from the second oil chamber 31 through the second oil chamber passage 32, the connecting oil passage 517 and the second oil passage 22 to the first oil passage 21 and then enters the first oil chamber 11. The oil pushes the piston 2 to move axially backward, causing the piston rod 3 to retract into the cylinder 1. When the piston rod 3 encounters resistance when extending or retracting, and the oil in the first oil chamber 11 and the second oil chamber 31 is overpressurized, pressure safety relief can be achieved through the bridge overflow circuit 37.

[0035] Example 2: like Figure 3 As shown, the cylinder body 1 is cylindrical, and an annular guide sleeve is provided at the cylinder head of the cylinder body 1. An oil port 12 is provided on the side wall of the cylinder body 1 near the guide sleeve for injecting oil. A thread is provided at the cylinder head of the cylinder body 1, and the guide sleeve is installed in the cylinder body 1 through the thread. A hole is opened at the center of the bottom of the cylinder body 1. A drive device 4 is provided at one end of the rodless chamber. A piston 2 is provided inside the cylinder body 1. The piston 2 is fixedly connected to the piston rod 3. A sealed first oil chamber 11 is formed between the piston 2, the piston rod 3 and the guide sleeve. The piston 2 can be driven to reciprocate axially in the cylinder body 1 by the drive device 4.

[0036] like Figure 5As shown, piston 2 includes housing 521 and housing rear cover 522. The end of housing 521 is fixedly connected to piston rod 3. Housing 521 is axially engaged with cylinder 1. A sealing ring is provided at the engagement point between housing 521 and cylinder 1. An axial through hole is provided in the middle of piston 2. Piston rod 32 extends out of cylinder 1 through guide sleeve. Piston rod 3 is connected to guide sleeve shaft hole. A sealing ring is provided in the inner hole of guide sleeve. A cavity is provided inside piston rod 3. Drive device 4 is fixed to the center of the outer side of cylinder bottom of cylinder 1 by bolts. The output shaft of drive device 4 is fixedly connected to drive rod 41. Drive device 4 can be a servo motor, hydraulic motor, engine with gearbox, or any drive device with a forward and reverse output shaft. The drive rod 41 is a splined shaft. The connection between the drive rod 41 and the output shaft of the drive device 4 is located in the central hole at the bottom of the cylinder 1. A sealing ring is installed in the central hole at the bottom of the cylinder. A limiting groove is installed on the inner side of the central hole at the bottom of the cylinder. The diameter of the limiting groove is larger than the diameter of the central hole at the bottom of the cylinder, forming an annular surface. A convex ring that matches the limiting groove is fixedly installed at the upper end of the drive rod 41. The convex ring can abut against the annular surface of the limiting groove and block the axial force of the drive rod 41 during the operation of the piston part 3. The drive rod 41 extends through the axial through hole in the middle of the piston 2 into the cavity inside the piston rod 3. The drive rod piston 34 is installed in the cavity inside the piston rod 3. A T-shaped head is provided at one end of the drive rod 41 and the drive rod piston 34. A T-shaped groove is provided inside the drive rod piston 34 to fit the T-shaped head at the end of the drive rod 41. The drive rod piston 34 is fastened to the end of the drive rod 41. The T-shaped groove inside the drive rod piston 34 can prevent the drive rod piston 34 from rotating with the drive rod 41, thus avoiding wear of the seal. The outer edge of the drive rod piston 34 is tightly fitted with the inner wall of the piston rod 3. Two sealing rings are provided on the outer edge of the drive rod piston 34. The inner end face of the drive rod piston 34 and the piston rod 3 form a drive rod cavity 33. A lubricating oil passage 35 is provided inside the drive rod piston 34. One end of the lubricating oil passage 35 is located between the two sealing rings of the drive rod piston 34, and the other end is connected to the T-groove of the drive rod piston 34. Thus, during the movement of the piston rod 3, when the second oil chamber 31 is filled with oil, the oil that leaks through the sealing ring on the drive rod piston 34 near the second oil chamber 31 can lubricate the connection between the drive rod 41 and the drive rod piston 34. The space between the drive rod piston 34 and the end of the piston rod 3 forms the second oil chamber 31. The side wall of the piston rod 3 is provided with a second oil chamber passage 32 and a pressure regulating oil passage 36. A bridge overflow circuit 37 is provided on the pressure regulating oil passage 36.

[0037] The piston 2 also houses a hydraulic drive assembly, which includes a housing 521 and a rear cover 522 mounted behind the housing 521. A sealing ring is provided on the outer edge of the housing 521. Oil passage 1 21 and oil passage 22 are provided inside the housing 521. The flange of the housing 521 is bolted to the piston rod 32. The hydraulic drive assembly includes a swashplate support 523 nested inside the housing 521 and a swashplate 525 with a clearance fit to the swashplate support 523. An oil distribution plate 524 and a straight plate 526 connected to the oil distribution plate are nested on the rear cover 522. The circumference between the swashplate 525 and the straight plate 526... Several plunger assemblies 527 are evenly distributed. At the middle of the plunger assemblies 527, the swashplate 525 and the straight plate 526 are hinged together by a ball joint 528 and pressure plates 529 on both sides of the ball joint 528. Splined through holes are provided at the axial through holes of the swashplate 525 and the straight plate 526. When the drive rod 41 passes through, the splined through hole can engage with the spline of the drive rod 41. When the drive rod 41 rotates, it drives the swashplate 525 and the straight plate 526 to rotate through the splined through hole. At this time, the plunger assemblies 527 inside the hydraulic drive device begin to reciprocate axially in sequence to distribute oil, and drive the piston 2 to reciprocate axially along the drive rod 41.

[0038] like Figure 8 As shown, the bridge-type overflow circuit 37 includes a check valve 371, a check valve 372, a check valve 373, a check valve 374, and an overflow valve 375. One end of the overflow valve 375 is connected to the check valves 371 and 372, and the other end of the overflow valve 375 is connected to the check valves 373 and 374. The inlet of the check valve 371 and the outlet of the check valve 373 are connected to the first oil chamber 11 through the pressure regulating oil circuit 36. The inlet of the check valve 372 and the outlet of the check valve 374 are connected to the second oil chamber 31 through the other end of the pressure regulating oil circuit 36. The oil in the first oil chamber 11 enters from the pressure regulating oil circuit 36, passes through the one-way valve 371, the overflow valve 375, the one-way valve 374 and the other end of the pressure regulating oil circuit 36 ​​to enter the second oil chamber 31. The oil in the second oil chamber 31 enters from the pressure regulating oil circuit 36, passes through the one-way valve 372, the overflow valve 375, the one-way valve 373 and the other end of the pressure regulating oil circuit 36 ​​to enter the first oil chamber 11.

[0039] like Figure 9 , Figure 10 As shown, the cross-sectional area A of the first oil chamber 11 is the same as the cross-sectional area B of the second oil chamber 31, A = A1 - A2, where A1 is the outer diameter of the first oil chamber 11 and A2 is the inner diameter of the first oil chamber 11. Since A and B have the same cross-sectional area, the volume change of the two oil chambers is the same during the oil distribution process. Compared with the area difference between the rod chamber and the rodless chamber of a conventional hydraulic cylinder, this solves many hydraulic control problems under constant speed conditions. Under rated load and without external interference, the displacement and feed displacement can be estimated by the number of motor rotations, eliminating the need for a displacement sensing device.

[0040] In use, piston 3 is located at the bottom of cylinder 1. When drive device 4 is started, drive device 4 drives drive rod 41 to start rotating. During the rotation of drive rod 41, drive rod 41 engages with the spline through hole inside the hydraulic drive assembly, driving the hydraulic drive assembly to start running. By distributing oil, piston 2 moves along the overall axial direction of drive rod 41. Oil enters oil passage 21 from first oil chamber 11, and is distributed by hydraulic drive assembly through oil passage 22 and the second oil chamber passage 32 connected to it into second oil chamber 31, pushing piston rod 3 out of guide sleeve. When piston rod 3 is to retract into cylinder 1, drive device 4 rotates in the opposite direction, driving hydraulic drive assembly to distribute oil in the opposite direction, distributing oil from second oil chamber 31 through second oil chamber passage 32 and oil passage 22 to oil passage 21 and then into first oil chamber 11. Oil pushes piston 2 to move axially backward, driving piston rod 3 to retract into cylinder 1.

[0041] Example 3: like Figure 11 , 12 As shown in Figure 13, the difference between Embodiment 3 and Embodiment 1 is that a passage 6 is provided inside the bottom of the cylinder body 1, a passage 7 is provided inside the drive rod 41, one end of the passage 7 is connected to the passage 6, two sealing rings are provided at the passage 7, and the other end is provided on the side of the drive rod piston 34 in the drive rod cavity 33 and is connected to the drive rod cavity 33. A through hole 8 is provided on the side wall of the bottom of the cylinder body 1.

[0042] During use, the cooling medium enters through passage 6. As the piston rod 3 retracts, the volume of the drive rod cavity 33 expands, and the cooling medium enters the drive rod cavity 33 through passage 7. When the piston rod 3 extends, the drive rod cavity 33 is compressed, and the cooling medium enters the rodless cavity of the cylinder 1 through the gap hole 9 between the spline shaft of the drive rod 41 and the internal gear sleeve 518 of the hydraulic drive assembly. When the piston rod 3 retracts again, the cooling medium in the rodless cavity can be discharged from the through hole 8 on the side wall of the cylinder bottom 1. The cooling medium can also flow in the reverse direction, entering through the through hole 8 and then being discharged through passage 6.

[0043] Example 4: like Figure 14The piston 3 is equipped with a fluid replenishment mechanism 38, which includes an end cap 381, an isolation piston 382, ​​an air inlet 383, an air chamber 384, a fluid filling chamber 385, and a replenishment oil passage 386. The piston rod end is provided with a cavity to accommodate the reciprocating motion of the isolation piston 382. The end cap 381 is provided at the rod end to close the cavity. The isolation piston 382 divides the cavity into an air chamber 384 and a fluid filling chamber 385. The end cap 381 is provided with an air inlet 383 that connects to the air chamber 384. The fluid filling chamber 385 is connected to the outlet of the overflow valve 375, the inlet of the three-way valve 373 and the four-way valve 374 through the replenishment oil passage 386. High-pressure gas is injected into the air chamber 384 through the air inlet 383. The high-pressure gas pushes the isolation piston 382 to compress the fluid filling chamber 385, so that the pressure oil is supplied to the three-way valve 373 or the four-way valve 374, thereby achieving oil replenishment when the first oil chamber 11 or the second oil chamber 31 is under low pressure.

[0044] The hydraulic drive components in the embodiments of this patent document are mainly illustrated using internal meshing gear structures and piston structures as typical hydraulic elements. The structural design, working characteristics, and application methods of these components in hydraulic systems are specifically disclosed, providing a concrete reference for the implementation of the technical solution. It should be noted that the above embodiments are merely representative examples illustrating the core innovations, and the actual technical scope involved is not limited to these examples. In devices related to this solution, the hydraulic drive components may also include other hydraulic elements not specifically described in the embodiments, such as hydraulic motors, hydraulic pumps, cycloidal motors, etc. Hydraulic motors include gear motors and piston motors, and hydraulic pumps include gear pumps or piston pumps, etc. These elements, together with the pump-type elements in the embodiments, constitute a complete hydraulic system functional module, all of which fall within the technical scope covered by this invention.

[0045] Under specific operating conditions, this invention can also be used as a reverse power generation device. For example, in a tidal energy conversion device, the bidirectional tidal force drives the piston rod to move forward / backward, causing the oil in the first and second oil chambers to flow through the hydraulic drive assembly, which in turn rotates the hydraulic drive assembly and drives the drive device to rotate through the drive rod. When the drive device is a motor, it can output electrical energy in reverse.

Claims

1. A high-load electro-hydraulic cylinder, comprising a cylinder body (1), a piston (2) and a piston rod (3) disposed within the cylinder body (1), and a first oil chamber (11) formed between the cylinder body (1) and the piston rod (3), characterized in that: A drive device (4) is provided at one end of the rodless chamber of the cylinder (1), and a drive rod (41) is provided inside the cylinder (1). The output shaft of the drive device (4) is fixedly connected to the tail end of the drive rod (41). A cavity is provided inside the piston rod (3). The drive rod (41) extends from the output shaft end of the drive device (4) into the cavity of the piston rod (3). A drive rod piston (34) is installed at the front end of the drive rod (41). A second oil chamber (31) is formed between the front end face of the drive rod piston (34) and the piston rod (3). A drive rod cavity (33) is formed between the rear end face of the drive rod piston (34) and the piston rod (3). A piston cavity (33) is provided inside the piston (2). There is a cavity for installing the hydraulic drive assembly. The piston body of the piston (2) is provided with an oil passage for connecting the hydraulic drive assembly and the first oil chamber (11). The piston body of the piston (2) and the piston rod (3) are provided with interlocking oil passages to connect the hydraulic drive assembly and the second oil chamber (31). The drive rod (41) is provided with axially extending key teeth on its radial circumferential surface. The hydraulic drive assembly includes a transmission input component that is connected to the drive rod (41). The transmission input component is provided with a meshing hole. The inner wall of the meshing hole is provided with key teeth axially. The key teeth of the drive rod (41) mesh with the key teeth of the meshing hole of the transmission input component.

2. The high-load electro-hydraulic control cylinder as described in claim 1, characterized in that: The hydraulic drive assembly includes an internal gear (514), an external gear (515), and an oil separator (516), with the external gear (515) serving as the transmission input.

3. A high-load electro-hydraulic control cylinder as described in claim 1, characterized in that: The hydraulic drive assembly includes a swashplate support (523), a swashplate (525), a piston assembly (527), a straight plate (526), ​​a distributor plate (524), a ball joint (528), and pressure plates (529) on both sides. The swashplate (525) and the straight plate (526) serve as transmission input components. The swashplate support (523), the piston assembly (527), the straight plate (526), ​​the distributor plate (524), the ball joint (528), and the pressure plates (529) on both sides are all provided with through holes for the drive rod (41) to pass through.

4. A high-load electro-hydraulic control cylinder as described in claim 2, characterized in that: The piston (2) includes a ring body (512) and a front cover (511) and a rear cover (513) disposed on both sides of the ring body (512). The ring body (512) is connected to the cylinder body (1) shaft. The front cover (511) is fixedly connected to the piston rod (3). The front cover (511) is provided with a connecting oil passage (517). The ring body (512) is provided with an oil passage one (21) and an oil passage two (22). The piston rod (3) is provided with a second oil chamber passage (32) connecting the second oil chamber (31) inside the side wall. The oil passage one (21) connects the hydraulic drive assembly to the first oil chamber (11). One end of the oil passage two (22) is connected to the drive hydraulic assembly, and the other end is connected to the second oil chamber passage (32).

5. A high-load electro-hydraulic control cylinder as described in claim 3, characterized in that: The piston (2) includes a housing (521) and a housing cover (522) installed behind the housing (521). The housing (521) is engaged with the bore shaft of the cylinder (1). The housing (521) is provided with an oil passage one (21) and an oil passage two (22). The oil passage one (21) is connected to the first oil chamber (11), and the oil passage two (22) is connected to the second oil chamber passage (32).

6. A high-load electro-hydraulic control cylinder as described in any one of claims 1-5, characterized in that: The area of ​​the annular cross-section A of the first oil cavity (11) is the same as the area of ​​the cross-section B of the second oil cavity (31).

7. A high-load electro-hydraulic control cylinder as described in any one of claims 1-5, characterized in that: The cylinder body (1) has a through hole at the bottom. The output shaft of the drive device (4) is connected to the drive rod (41), and a limiting groove is provided on the side near the cylinder body (1). A convex ring that matches the limiting groove is fixedly provided at the end of the drive rod (41). The convex ring and the limiting groove cooperate to offset the axial force of the drive rod (41).

8. A high-load electro-hydraulic control cylinder as described in any one of claims 1-6, characterized in that: The drive rod (41) is provided with a T-shaped head at the end, and the drive rod piston (34) is provided with a T-shaped groove inside to fit the T-shaped head at the end of the drive rod (41), so that the drive rod piston (34) does not rotate with the drive rod (41) and avoids wear of the seal.

9. A high-load electro-hydraulic control cylinder as described in claim 9, characterized in that, The outer edge of the drive rod piston (34) is provided with a lubricating oil passage (35), and two sealing rings are provided on both sides of the lubricating oil passage (35). The lubricating oil passage (35) is connected to the T-groove inside the drive rod piston (34).

10. A high-load electro-hydraulic control cylinder as described in any one of claims 1-5, characterized in that: The piston rod (3) is provided with a pressure regulating oil circuit (36) at its end. The pressure regulating oil circuit (36) connects the first oil chamber (11) and the second oil chamber (31). A bridge overflow circuit (37) is provided on the pressure regulating oil circuit (36). The bridge overflow circuit (37) includes a check valve one (371), a check valve two (372), a check valve three (373), a check valve four (374), and an overflow valve (375). The oil in the first oil chamber (11) enters the pressure regulating oil circuit (36) and can enter the second oil chamber (31) after passing through the check valve one (371), the overflow valve (375), and the check valve four (374). The oil in the second oil chamber (31) enters the first oil chamber (11) after passing through the check valve two (372), the overflow valve (375), and the check valve three (373).

11. A high-load electro-hydraulic control cylinder as described in claim 1, characterized in that: The drive unit (4) can be a servo motor, a hydraulic motor, an engine with a gearbox, or any device that can provide forward and reverse driving force.

12. A high-load electro-hydraulic control cylinder as described in claim 1, characterized in that: The hydraulic drive assembly can be a hydraulic motor, a hydraulic pump, or a cycloidal motor, wherein the hydraulic motor includes a gear motor or a piston motor, and the hydraulic pump includes a gear pump or a piston pump.

13. A high-load electro-hydraulic control cylinder as described in claim 2, characterized in that: The external gear (515) includes a gear body and an internal gear sleeve (518) at the center of the gear body. The internal gear sleeve (518) has an axial through hole at its center, and a key tooth adapted to the drive rod (41) is provided in the axial through hole.

14. A high-load electro-hydraulic control cylinder as described in claim 2, characterized in that: The cylinder (1) also includes a temperature control circuit, which includes a first passage (6) inside the cylinder bottom and a second passage (7) inside the drive rod (41). The first passage (6) and the second passage (7) are connected. A sealing ring is provided at the connection between the first passage (6) and the second passage (7). The cooling medium enters the second passage (7) in the drive rod (41) from the first passage (6) and can be discharged from the first passage (6) again after the cooling cycle.

15. A high-load electro-hydraulic control cylinder as described in claim 14, characterized in that: The second passage (7) connects to the drive rod cavity (33). A gap hole (9) is provided between the drive rod (41) and the transmission input component. The cooling medium enters the drive rod cavity (33) through the first passage (6) and the second passage (7), then enters the rodless cavity through the gap hole (9), and is discharged through the through hole (8) on the side wall of the rodless cavity.

16. A high-load electro-hydraulic control cylinder as described in any one of claims 1-5, characterized in that: An oil port (12) is provided on the side wall of the first oil cavity (11).

17. A driving method for a high-load electro-hydraulic cylinder, characterized in that: When the piston rod (3) is about to extend out of the cylinder (1), the drive device (4) is started. The drive device (4) drives the drive rod (41) to start rotating. The drive rod (41) provides rotational driving force for the hydraulic drive assembly. During the operation of the hydraulic drive assembly, the oil enters the first oil passage (21) from the first oil chamber (11). The hydraulic drive assembly distributes the oil in the first oil passage (21) to the second oil passage (22) and then enters the second oil chamber (31). The pressure inside the second oil chamber (31) increases, causing the volume of the second oil chamber (31) to expand. At the same time, the volume of the first oil chamber (11) shrinks. The piston (2) begins to move along the overall axial direction of the drive rod (41), pushing the piston rod (32) to extend. When the piston rod (3) is to retract into the cylinder (1), the drive device (4) rotates in the opposite direction, driving the hydraulic drive assembly to distribute the oil in the opposite direction. The oil is then distributed from the second oil chamber (31) and the second oil passage (22) to the first oil passage (21) and enters the first oil chamber (11). The pressure inside the first oil chamber (11) increases, causing the volume of the first oil chamber (11) to increase while the volume of the second oil chamber (31) decreases. The oil pushes the piston (2) to move axially backward along the drive rod (41), causing the piston rod (3) to retract into the cylinder (1).

18. The driving method for a high-load electro-hydraulic cylinder as described in claim 17, characterized in that: The cross-sectional area A of the first oil chamber (11) is the same as the cross-sectional area B of the second oil chamber (31). During the operation of the hydraulic drive assembly, the volume change of the first oil chamber (11) and the second oil chamber (31) is the same. Under rated load and without external interference, the displacement and feed displacement can be estimated by the number of motor rotations.

19. The driving method for any high-load electro-hydraulic cylinder as described in claim 17 or 18, characterized in that: When the pressure difference between the second oil chamber (31) and the first oil chamber (11) is too large, the oil in the second oil chamber (31) can enter the first oil chamber (11) through the pressure regulating oil circuit (36) and then enter the first oil chamber (11) through the check valve 2 (372), the overflow valve (375) and the check valve 3 (373) in the bridge overflow circuit (37), or the oil in the first oil chamber (11) can enter the second oil chamber (31) through the pressure regulating oil circuit (36) and then enter the second oil chamber (31) through the check valve 1 (371), the overflow valve (375) and the check valve 4 (374) in the bridge overflow circuit (37), thereby achieving pressure-safe overflow.

20. A high-load electro-hydraulic control cylinder as described in claim 10, characterized in that: The piston (3) is provided with a liquid replenishment mechanism (38), which includes an end cap (381), an isolation piston (382), an air inlet (383), an air chamber (384), a liquid filling chamber (385), and an oil replenishment channel (386). The piston (3) rod end is provided with a cavity to accommodate the reciprocating motion of the isolation piston (382), and the rod end is provided with an end cap (381) to close the cavity. The isolation piston (382) divides the cavity into an air chamber (384) and a liquid filling chamber (385). The end cap (381) is provided with an air inlet (383) that connects to the air chamber (384). The liquid filling chamber (385) is connected to the outlet of the overflow valve (375), the inlet of the three-way valve (373), and the four-way valve (374) through the oil replenishment channel (386).

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