Shock-resistant characteristic heavy-load electric cylinder based on hydraulic buffering mechanism and control method thereof

Abstract

The invention provides an anti-impact characteristic heavy-load electric cylinder based on a hydraulic buffering mechanism and a control method thereof, and relates to the technical field of power driving systems. Comprising a motor, a controller and a speed reducing mechanism, and an output shaft of the speed reducing mechanism is connected with a lead screw; a piston, a piston rod and a lead screw nut connected to the lead screw are arranged in the cylinder barrel, the lead screw nut is connected with the piston, and the piston is connected with the piston rod. The interior of the piston rod is hollow so as to form a movable cavity for the lead screw to move; the piston is suitable for dividing the interior of the cylinder barrel into a rod cavity and a rodless cavity which are isolated from each other, and an oil through hole for communicating the rodless cavity with the movable cavity is formed in the piston; the hydraulic system is provided with a first oil way communicated to the rodless cavity and a second oil way connected to the rod cavity; the first oil way and the second oil way are connected to an oil supply system through a reversing valve. According to the scheme, the heavy load bearing capacity of the electric cylinder is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power drive systems, and more particularly, to a heavy-duty electric cylinder with anti-shock characteristics based on a hydraulic buffer mechanism and its control method. Background Art

[0002] As a representative of pure electric drive in linear actuators, the electric cylinder uses an electric motor as the main power source. The motor drives a lead screw or nut of different forms to rotate through a speed reducer, converting the rotational motion into a linear motion of the nut or lead screw. The nut or lead screw is connected to a push rod to perform reciprocating motion. Different from hydraulic cylinders, the electric cylinder realizes direct electric drive based on lead screw mechanical transmission, with high transmission efficiency, accurate control precision, and no oil loss, and is widely used in fields such as aerospace, robotics, and industrial automation. However, the direct drive of the electric motor in the electric cylinder limits its ability to effectively drive heavy loads. Also, because of the rigid connection such as bolts or threads between the lead screw nut and the push rod, when subjected to external impact loads, the lead screw pair is prone to jamming and excessive wear, and even problems such as thread fracture and ball crushing, reducing the reliability of the electric cylinder and shortening its service life.

[0003] Although the current roller screw effectively improves its load-bearing capacity through line contact, the roller screw is known for its high precision and high response speed, and its installation and maintenance are complex. Especially when subjected to impact loads, the rigid connection without a buffer mechanism still has a serious impact on the rollers around the lead screw, increasing the maintenance difficulty. Therefore, the existing technologies of current electric cylinders are difficult to effectively drive heavy loads and mitigate impact loads. Summary of the Invention

[0004] The present invention discloses a heavy-duty electric cylinder with anti-shock characteristics based on a hydraulic buffer mechanism, aiming to solve the problems that current electric cylinders are difficult to effectively drive heavy loads and mitigate impact loads.

[0005] The present invention adopts the following solutions: A heavy-duty electric cylinder with anti-shock characteristics based on a hydraulic buffer mechanism includes an electric motor, a controller connected to the electric motor, and a reduction mechanism connected to the output shaft of the electric motor. The output shaft of the reduction mechanism is connected to a lead screw; it further includes: a hydraulic system, a cylinder barrel, A piston, a piston rod, and a lead screw nut connected to the lead screw are arranged inside the cylinder barrel, and the lead screw nut is connected to the piston, and the piston is connected to the piston rod; the inside of the piston rod is hollow to form a movable cavity for the lead screw to move. The piston is adapted to divide the inside of the cylinder barrel into a rod chamber and a rodless chamber that are isolated from each other, and an oil through hole communicating the rodless chamber and the movable cavity is provided on the piston. The hydraulic system is provided with a first oil passage communicating with the rodless chamber and a second oil passage connected to the rod chamber; the first oil passage and the second oil passage are connected to the oil supply system through a reversing valve, and the oil supply system is adapted to supply oil to the rodless chamber or the rod chamber to increase the oil pressure in the corresponding chamber to counteract part of the impact load borne by the piston rod; An end cover of the piston rod is provided at an outer end of the piston rod, and a small piston rod ear sling is provided on the end cover of the piston rod; wherein, the small piston rod ear sling includes a load connection part, a piston part, and a connecting shaft connecting the piston part and the load connection part, and the connecting shaft is movably inserted into a through hole on the end cover of the piston rod; the piston part is movably arranged in the movable chamber and seals an outer end of the movable chamber; disc spring groups sleeved on the connecting shaft are respectively arranged on both sides of the end cover of the piston rod; when the load connection part bears a heavy load, the hydraulic oil in the movable chamber is compressed by the disc spring groups and the piston part to buffer part of the impact load.

[0006] Further, a sealed chamber is formed between the end cover of the piston rod and the piston part, the disc spring groups are arranged in the sealed chamber, and the sealed chamber is connected with an accumulator, and a switch valve is arranged on the accumulator; when the piston rod extends, the switch valve is opened to enable the accumulator to supply oil to the sealed chamber, and when the piston rod retracts, the switch valve cuts off the action of the accumulator; the oil supply system is provided with a third oil passage to be connected to the sealed chamber, and a check valve is arranged on the third oil passage to enable the third oil passage to only convey hydraulic oil from the oil supply system to the sealed chamber, and when the piston rod retracts, the oil supply system is adapted to supply oil to the sealed chamber to push the piston part of the small piston rod ear sling to retract.

[0007] Further, a force sensor connected to the controller is arranged on the small piston rod ear sling, and the controller is adapted to control the motor to reduce the speed to improve the bearing capacity when the force sensor detects an increase in the external load borne by the small piston rod ear sling, and the oil supply system is adapted to increase the output oil to counteract the impact.

[0008] Further, the oil supply system includes a servo motor, a variable displacement pump connected to the servo motor, and a fuel tank connected to the variable displacement pump, the variable displacement pump is connected to the first oil passage and the second oil passage through a reversing valve, and the third oil passage is connected in parallel to the second oil passage.

[0009] Further, a first pressure sensor connected to the controller is provided on the first oil path, a second pressure sensor connected to the controller is provided on the second oil path, a first overflow valve is provided on the first oil path, a second overflow valve is provided on the second oil path, and a third overflow valve is provided on the third oil path. When the oil pressure on the corresponding oil path exceeds the set pressure of the corresponding overflow valve, pressure relief is carried out through the corresponding overflow valve to prevent pressure shock in the cavity connected to the corresponding oil path.

[0010] Further, the cylinder barrel includes a left cylinder head and a right cylinder head provided at both ends. An axial rotary seal ring is provided between the left cylinder head and the lead screw. A second Y-shaped seal ring, a second support ring, and a dust ring are sequentially provided between the right end cover and the piston rod from inside to outside; a first support ring is provided between the outer side of the piston and the inner wall of the cylinder barrel, and first Y-shaped seal rings are provided on both sides of the first support ring; a bi-directional seal ring is provided between the outer side of the piston part of the small piston rod ear hanger and the inner wall of the cylinder barrel, and third support rings are provided on both sides of the bi-directional seal ring.

[0011] Further, the piston is connected to the lead screw nut by bolts; the piston and the piston rod are connected by threads.

[0012] The present invention also provides a control method for an impact-resistant heavy-duty electric cylinder based on a hydraulic buffer mechanism. When the piston rod extends, under the heavy-duty driving condition without impact load, the steps are as follows: S1: The rotation speed of the motor is reduced by the speed reducer and then drives the lead screw to rotate, and the lead screw drives the lead screw nut to move forward; S2: The lead screw nut moves, driving the piston, the piston rod, and the piston rod end cover to move forward as a whole. When the piston rod end cover moves forward, it will squeeze the disc spring group on the right side; S3: When the whole piston rod extends, the switching valve is opened to enable the accumulator to fill oil into the closed cavity; S4: The rotation of the servo motor in the hydraulic system drives the variable displacement pump to output oil to the rodless cavity: when the hydraulic oil enters the rodless cavity through the first oil path, a part acts on the lead screw nut and the piston, and the other part enters the movable cavity through the oil passage hole and acts on the left side of the small piston rod ear hanger to drive the small piston rod ear hanger to extend; During the process of the piston rod extending, when the load suddenly increases, the buffering process is as follows: The disc spring group on the right side is squeezed again, the extension speed of the small piston rod ear hanger slows down, and the oil in the movable cavity and the rodless cavity is compressed to relieve a part of the suddenly increased external load; At the same time, the force sensor transmits a signal to the controller, and the controller controls the motor speed to decrease, increases the torque to increase the bearing capacity of the lead screw, and slows down the impact effect; Meanwhile, the controller synchronously controls the servo motor to drive the variable displacement pump to increase the inclination angle and improve the displacement, so as to increase the oil pressure entering the active chamber and the rodless chamber, offsetting a part of the suddenly increased external load. Meanwhile, when the oil pressure used to offset the external load increases beyond the set pressure of the first relief valve, or the second relief valve, or the third relief valve, the corresponding relief valve orifice opens to relieve pressure, preventing pressure shock in the system.

[0013] The present invention also provides another control method for a heavy-duty electric cylinder with anti-shock characteristics based on a hydraulic buffer mechanism. When the piston rod retracts, under the heavy-duty driving condition without impact load, the steps are as follows: S1: The rotation speed of the motor is reduced by the speed reducer and then drives the lead screw to rotate, and the lead screw drives the lead screw nut to move backward. S2: The lead screw nut moves, driving the piston, the piston rod and the piston rod end cover to move backward as a whole. When the piston rod end cover moves backward, it will squeeze the disc spring group on the left side. S3: When the whole piston rod retracts, the switching valve cuts off the function of the accumulator. S4: The rotation of the servo motor in the hydraulic system drives the variable displacement pump to output oil to the rod chamber: when the hydraulic oil enters the rod chamber through the second oil circuit, part of the oil enters the rod chamber to push the piston to retract, and the other part enters the closed chamber through the check valve, acting on the left side of the small piston rod ear suspension and forcing the small piston rod ear suspension to retract. During the retraction process of the piston rod, when the load suddenly increases, the buffering process is as follows: The disc spring group on the left side is squeezed again, the retraction speed of the small piston rod ear suspension slows down, and the oil in the closed chamber and the rod chamber is compressed to relieve a part of the suddenly increased external load. Meanwhile, the force sensor transmits the signal to the controller, and the controller controls the motor speed to decrease, increasing the torque to improve the bearing capacity of the lead screw and reducing the impact effect. Meanwhile, the controller synchronously controls the servo motor to drive the variable displacement pump to increase the inclination angle and improve the displacement, so as to increase the oil pressure entering the closed chamber and the rod chamber, offsetting a part of the suddenly increased external load. Meanwhile, when the oil pressure used to offset the external load increases beyond the set pressure of the first relief valve, or the second relief valve, or the third relief valve, the corresponding relief valve orifice opens to relieve pressure, preventing pressure shock in the system.

[0014] Beneficial effects: 1. The heavy-duty electric cylinder with anti-shock characteristics of the present invention based on a hydraulic buffer mechanism highly integrates the electric cylinder structure and the hydraulic system, mainly driven by electricity and supplemented by hydraulic drive, with electric-hydraulic cooperation to jointly drive the load, improving the maximum thrust of the electric cylinder and solving the problem that the electric cylinder is difficult to drive heavy loads due to low power density.

[0015] 2. The heavy-duty electric cylinder with impact resistance characteristics based on the hydraulic buffer mechanism of the present invention converts the rigid connection at the traditional ear sling of the electric cylinder into an elastic connection of disc springs, and then combines the compressibility of hydraulic oil to provide sufficient buffer space. Finally, the impact load is offset by the increased oil pressure, and this buffer mechanism can take effect when the piston rod extends and retracts. Description of the Drawings

[0016] Figure 1 is a schematic cross-sectional structure diagram of a heavy-duty electric cylinder with impact resistance characteristics based on the hydraulic buffer mechanism according to an embodiment of the present invention; Figure 2 is a schematic installation structure diagram of the small piston rod ear sling of a heavy-duty electric cylinder with impact resistance characteristics based on the hydraulic buffer mechanism according to an embodiment of the present invention; Figure 3 is a schematic installation structure diagram of the piston and the lead screw nut of a heavy-duty electric cylinder with impact resistance characteristics based on the hydraulic buffer mechanism according to an embodiment of the present invention; Figure 4 is a schematic exploded structure diagram of the installation position of the small piston rod ear sling of a heavy-duty electric cylinder with impact resistance characteristics based on the hydraulic buffer mechanism according to an embodiment of the present invention; Figure 5 is a schematic working process diagram of a heavy-duty electric cylinder with impact resistance characteristics based on the hydraulic buffer mechanism according to an embodiment of the present invention; Figure 6 is another schematic working process diagram of a heavy-duty electric cylinder with impact resistance characteristics based on the hydraulic buffer mechanism according to an embodiment of the present invention; Reference numerals: controller 1, motor 2, reduction box 3, small box body 4, bearing 5, spacer 6, shaft rotary seal ring 7, left cylinder head 8, left buffer block 9, first static seal ring 10, lead screw 11, cylinder barrel 12, rodless cavity 13, lead screw nut 14, piston 15, oil through hole 16, first support ring 17, first Y-shaped seal ring 18, rod cavity 19, piston rod 20, movable cavity 21, right buffer block 22, second static seal ring 23, right cylinder head 24, second Y-shaped seal ring 25, second support ring 26, dust-proof ring 27, third support ring 28, bidirectional seal ring 29, disc spring group 30, sealed cavity 31, piston rod end cover 32, third static seal ring 33, one-way seal ring 34, cylindrical rubber dust-proof sleeve 35, small piston rod ear sling 36, first pressure sensor 37, second pressure sensor 38, force sensor 39, first overflow valve 40, second overflow valve 41, third overflow valve 42, reversing valve 43, one-way valve 44, switch valve 45, accumulator 46, servo motor 47, variable displacement pump 48, fuel tank 49. Detailed Embodiments

[0017] Embodiment 1 Combined with Figures 1 to 4As shown in the figure, this embodiment provides a heavy-duty electric cylinder with anti-impact characteristics based on a hydraulic buffer mechanism, which includes a motor 2, a controller 1 connected to the motor 2, and a reduction mechanism connected to the output shaft of the motor 2. The output shaft of the reduction mechanism is connected to a lead screw; it also includes: a hydraulic system, a cylinder barrel 12, A piston 15, a piston rod 20, and a lead screw nut connected to the lead screw are arranged inside the cylinder barrel 12, and the lead screw nut is connected to the piston 15, and the piston 15 is connected to the piston rod 20; the inside of the piston rod 20 is hollow to form a movable cavity 21 for the lead screw to move; The piston 15 is adapted to divide the inside of the cylinder barrel 12 into a rod chamber 19 and a rodless chamber 13 that are isolated from each other, and an oil passage hole 16 communicating the rodless chamber 13 and the movable cavity 21 is provided on the piston 15; The hydraulic system is provided with a first oil passage communicating with the rodless chamber 13 and a second oil passage connected to the rod chamber 19; the first oil passage and the second oil passage are connected to an oil supply system through a reversing valve 43, and the oil supply system is adapted to supply oil to the rodless chamber 13 or the rod chamber 19 to increase the oil pressure in the corresponding chamber to offset part of the impact load borne by the piston rod 20.

[0018] In this embodiment, the reduction mechanism adopts a reduction box 3. The controller 1 is installed on the motor 2. The output shaft of the motor 2 is connected to the gear set in the reduction box 3. The torque of the motor 2 is transmitted to the lead screw 11 through the reduction mechanism to form a folding electric cylinder. A pair of cylindrical roller bearings 5 and a spacer 6 for preventing collision are equipped on the smooth rod on the left side of the lead screw 11 and installed in the small box body 4. The left cylinder head 8 and the right cylinder head 24 are installed on the left and right sides of the cylinder barrel 12, and the piston 15 and the piston rod 20 are assembled inside. The two are connected by threads. In order to provide enough installation space for the lead screw 11, the middle parts of the piston 15 and the piston rod 20 are designed to be hollow, and the lead screw 11 and the lead screw nut 14 are assembled therein. The piston 15 and the lead screw nut 14 are connected by bolts. The inside of the cylinder body can be divided into a rodless chamber 13 and a rod chamber 19 by the piston 15. The left side of the piston 15 is the rodless chamber 13, and the right side is the rod chamber 19. Due to the lead screw 11 and the lead screw nut 14, the rodless chamber 13 and the movable cavity 21 of the piston rod 20 cannot be effectively sealed. Therefore, a number of oil passage holes 16 are provided on the piston 15 to meet the rapid flow between the two. Therefore, the rodless chamber 13 and the movable cavity 21 are connected as one chamber. In a preferred embodiment, the oil passage holes 16 are set to 6. Different from the existing electric cylinders, the structure adopted in this embodiment can ensure the rapid flow of oil, make reasonable use of the internal space of the electric cylinder, and has a large integration effect.

[0019] Combined with Figures 1 to 3As shown, in this embodiment, a piston rod end cover 32 is provided at the outer end of the piston rod 20, and a small piston rod ear sling 36 is provided on the piston rod end cover 32. Among them, the small piston rod ear sling 36 includes a load connection part, a piston 15 part, and a connecting shaft connecting the piston 15 part and the load connection part. The connecting shaft is movably inserted into a through hole on the piston rod end cover 32. The piston 15 part is movably arranged in the movable cavity 21 and seals the outer end of the movable cavity 21. Disc spring groups 30 sleeved on the connecting shaft are respectively arranged on both sides of the piston rod end cover 32. When the load connection part bears a heavy load, the hydraulic oil in the movable cavity 21 is compressed by the disc spring groups 30 and the piston 15 part to buffer part of the impact load.

[0020] Specifically, the tail of the piston rod 20 is designed as a small piston rod ear sling 36, which is installed inside the piston rod 20 and isolated by the piston rod end cover 32 in the middle. The piston rod end cover 32 and the piston rod 20 are connected by bolts. Thus, the lead screw nut 14, the piston 15, the piston rod 20, and the piston rod end cover 32 can be regarded as a whole and reciprocate under the rotation of the lead screw 11. Disc spring groups 30 are respectively assembled on the left and right sides of the piston rod end cover 32, and each disc spring group 30 is formed by arranging 6 disc springs to buffer the external impact load. Through combined installation, the disc spring groups 30 also have a supporting effect to prevent jamming due to lack of freedom between the small piston rod ear sling 36 and the piston rod 20.

[0021] In a preferred embodiment, a sealed cavity 31 is formed between the piston rod end cover 32 and the piston 15 part. The disc spring groups 30 are arranged in the sealed cavity 31, and the sealed cavity 31 is connected with an accumulator 46. A switching valve 45 is provided on the accumulator 46. When the piston rod 20 extends, the switching valve 45 is opened to enable the accumulator 46 to supply oil to the sealed cavity 31. When the piston rod 20 retracts, the switching valve 45 cuts off the action of the accumulator 46. The oil supply system is provided with a third oil circuit connected to the sealed cavity 31, and a one-way valve 44 is provided on the third oil circuit so that the third oil circuit can only make the hydraulic oil be transported from the oil supply system to the sealed cavity 31. When the piston rod 20 retracts, the oil supply system is adapted to supply oil to the sealed cavity 31 to push the piston 15 part of the small piston rod ear sling 36 to retract.

[0022] Combined Figure 1 and Figure 4As shown in the figure, specifically, the disc spring group 30 on the left is assembled in the closed cavity 31 and connected to the accumulator 46 through the switching valve 45 to replenish oil to the closed cavity 31. A cylindrical rubber dust cover 35 is assembled outside the disc spring group 30 on the right to prevent external dust and other particulate matters from entering the disc spring gaps. The small piston rod ear hanger 36 can reciprocate in the piston rod 20, and the moving distance is the maximum compression amount of the disc spring group 30. Different from the rigid connection between the push rod and the ear hanger in the existing electric cylinder, the solution of this embodiment uses elastic elements such as the disc spring group 30 to replace the rigid connection, so that it has the buffering effect for external impact loads.

[0023] Here, the function of the accumulator 46 is to replenish oil. Since the piston part in the small piston rod ear hanger 36 and the piston rod 20 are movable, when the piston rod 20 and the piston rod end cover 32 move forward, first, due to inertia, the small piston rod ear hanger 36 will remain stationary; second, because the piston rod 20 is driven by both electric drive and hydraulic drive, while the small piston rod ear hanger 36 is only driven by hydraulic drive, so the disc spring group on the right will be compressed, which causes the space of the closed cavity 31 to increase. By setting the accumulator 46, on the one hand, it can prevent the occurrence of cavitation and noise, and on the other hand, it can make the closed cavity 31 filled with oil. The closed cavity 31 filled with oil can ensure the quick response of the small piston rod ear hanger 36. Therefore, when the piston rod 20 extends, the accumulator 46 is used to replenish oil. However, when retracting, due to the third oil circuit, if the accumulator is not cut off, the oil in the third oil circuit will all enter the accumulator 46, which is not conducive to pushing the small piston rod ear hanger 36 to retract. Therefore, it is necessary to cut off the accumulator. Moreover, when retracting, the closed cavity 31 will always remain full of oil, and there is no need to replenish oil, so the switching valve can be directly used to cut off.

[0024] Preferably, a force sensor 39 connected to the controller 1 is provided on the small piston rod ear hanger 36. The controller 1 is adapted to control the motor 2 to reduce the speed to increase the bearing capacity when the force sensor 39 detects that the external load borne by the small piston rod ear hanger 36 increases, and the oil supply system is adapted to increase the output oil to offset the impact. The force sensor 39 can be a tension sensor or a pressure sensor.

[0025] The oil supply system described in this embodiment includes a servo motor 47, a variable displacement pump 48 connected to the servo motor 47, and a fuel tank 49 connected to the variable displacement pump 48. The variable displacement pump 48 is connected to the first oil circuit and the second oil circuit through a reversing valve 43, and the third oil circuit is connected in parallel to the second oil circuit. A first pressure sensor 37 connected to the controller 1 is provided on the first oil circuit, a second pressure sensor 38 connected to the controller 1 is provided on the second oil circuit, a first relief valve 40 is provided on the first oil circuit, a second relief valve 41 is provided on the second oil circuit, and a third relief valve 42 is provided on the third oil circuit. When the oil pressure on the corresponding oil circuit exceeds the set pressure of the corresponding relief valve, pressure relief is carried out through the corresponding relief valve to prevent pressure shock in the cavity connected to the corresponding oil circuit.

[0026] Specifically, an oil hole is opened in each of the rodless cavity 13 and the rod chamber 19, and a tubing is connected to form a first oil circuit and a second oil circuit. The oil passes through the servo motor 47 and the variable displacement pump 48 and enters the cavity through the reversing valve 43, while the oil in the return tubing enters the fuel tank 49 to form a cycle. An oil hole is also opened in the sealed cavity 31 at the tail of the piston rod 20 to connect the third oil circuit. When the piston rod 20 retracts, the switching valve 45 cuts off the action of the accumulator 46, and the oil in the hydraulic system can smoothly enter through the check valve 44, pushing the small piston rod ear hanger 36 to retract. Compared with the fixed thrust of the existing electric cylinder, the solution of this embodiment uses hydraulic oil for auxiliary drive, enabling it to have a heavy load capacity.

[0027] To detect the magnitude of the external load in real time, a force sensor 39 is equipped at the small piston rod ear hanger 36. When it is detected that the external load increases, the signal is transmitted to the controller 1. The controller 1 will reduce the speed of the motor 2 and increase the torque to improve the bearing capacity and mitigate the impact effect. The signal of the controller 1 will also be transmitted to the variable displacement pump 48 to increase the inclination angle and the displacement, outputting more oil to offset the impact. Here, two first pressure sensors 37, a second pressure sensor 38 and three relief valves are also assembled in the hydraulic system. When the oil pressure used to offset the impact load exceeds the set pressure of the relief valve, the relief valve orifice is opened for pressure relief to prevent pressure shock in the cavity.

[0028] The solution of this embodiment not only can assist in driving heavy loads by adding a hydraulic system, but also can use the oil pressure and the disc spring group 30 to mitigate the impact load. This function is continuously effective when the piston rod 20 moves reciprocally and has a high degree of integration.

[0029] Further, the cylinder barrel 12 includes a left cylinder head 8 and a right cylinder head 24 disposed at both ends. An axial rotary seal ring 7 is provided between the left cylinder head 8 and the lead screw. Between the right end cap and the piston rod 20, a second Y-shaped seal ring 25, a second support ring 26, and a dust seal 27 are sequentially arranged from inside to outside; between the outer side of the piston 15 and the inner wall of the cylinder barrel 12, a first support ring 17 is provided, and first Y-shaped seal rings 18 are respectively arranged on both sides of the first support ring 17. Between the outer side of the piston 15 portion of the small piston rod ear hanger 36 and the inner wall of the cylinder barrel 12, a bi-directional seal ring 29 is provided, and third support rings 28 are respectively arranged on both sides of the bi-directional seal ring 29. Specifically, since the cavity is filled with hydraulic oil, it is necessary to ensure the sealing performance of each chamber. To prevent the hydraulic oil in the rodless chamber 13 from leaking, a first static seal ring 10 is designed on the outer circle of the left cylinder head 8 to prevent the hydraulic oil from leaking from the cylinder barrel 12; an axial rotary seal ring 7 is designed on the inner circle to prevent the hydraulic oil from entering the small box body 4; a left buffer block 9 is also designed on the left cylinder head 8 to prevent the impact collision during retraction; two single-directional first Y-shaped seal rings 18 and a first support ring 17 are designed on the surface of the piston 15 to prevent the hydraulic oil from leaking between the rodless chamber 13 and the rod chamber 19; the right cylinder head 24 is provided with a second static seal ring 23, a second Y-shaped seal ring 25, a second support ring 26, and a dust seal 27 to prevent the hydraulic oil from leaking out and dust from entering the cavity, and a right buffer block 22 is assembled to prevent the impact collision during extension. At the small piston rod ear hanger 36, to ensure the hydraulic oil sealing performance, a third static seal ring 33 and a single-directional seal ring 34 are designed on the piston rod end cap 32 to prevent the hydraulic oil in the sealed chamber 31 from leaking when the compression disc spring group 30 moves; a bi-directional seal ring 29 and two third support rings 28 are designed between the small piston rod ear hanger 36 and the piston rod 20, which not only prevent the hydraulic oil from leaking but also have a supporting effect.

[0030] Through the structure of this embodiment, it has at least the following advantages: First, the highly integrated design of the hydraulic system and the electric cylinder structure. By incorporating the hydraulic system into the internal space of the electric cylinder and making full use of the hollow structures of the piston 15 and the piston rod 20 and the design of the oil passage hole 16, the rapid flow of hydraulic oil and hydraulic auxiliary drive are realized, significantly improving the maximum thrust of the electric cylinder and solving the problem of heavy-load drive. Second, the introduction of an elastic buffer mechanism. By changing the traditional ear hanger to a small piston rod ear hanger 36 and assembling disc spring groups 30 on both sides of the piston rod end cap 32, sufficient buffer effect and pressure accumulation time are provided, effectively alleviating the influence of external impact loads. Third, the control strategy of electro-hydraulic coordinated drive. By using a force sensor 39 and a pressure sensor to monitor the change of the external load in real time, and the controller 1 adjusts the rotation speed of the motor 2 and the displacement of the hydraulic system, the rapid response and precise control of the external impact load are realized.

[0031] Embodiment 2 Combined with Figures 5 to 6As shown in the figure, the present invention also provides a control method for a heavy-duty electric cylinder with anti-shock characteristics based on a hydraulic buffer mechanism. When the piston rod extends, in the heavy-duty driving condition without impact load, the steps are as follows: S1: The rotation speed of the motor 2 is reduced by the speed reducer 3 and then drives the lead screw 11 to rotate. The lead screw 11 drives the lead screw nut 14 to move forward; S2: The lead screw nut 14 moves, driving the piston 15, the piston rod 20, and the piston rod end cover 32 to move forward as a whole. When the piston rod end cover 32 moves forward, it will squeeze the disc spring group 30 on the right side; S3: When the entire piston rod 20 extends, the switching valve 45 is opened to enable the accumulator 46 to replenish oil to the closed cavity 31; S4: The rotation of the servo motor 47 in the hydraulic system drives the variable displacement pump 48 to output oil to the rodless cavity 13: When the reversing valve 43 switches to the left and the hydraulic oil enters the rodless cavity 13 through the first oil circuit, a part acts on the lead screw nut 14 and the piston 15, and the other part enters the movable cavity 21 through the oil passage hole 16 and acts on the left side of the small piston rod ear hanger 36 to drive the small piston rod ear hanger 36 to extend; During the extension of the piston rod 20, when the load suddenly increases, the buffering process is as follows: The disc spring group 30 on the right side is squeezed again, the extension speed of the small piston rod ear hanger 36 slows down, and the oil in the movable cavity 21 and the rodless cavity 13 is compressed to relieve a part of the suddenly increased external load; At the same time, the force sensor 39 transmits a signal to the controller 1, and the controller 1 controls the rotation speed of the motor 2 to decrease, increases the torque to increase the bearing capacity of the lead screw 11, and slows down the impact effect; At the same time, the controller 1 synchronously controls the servo motor 47 to drive the variable displacement pump 48 to increase the inclination angle and the displacement, so that the oil pressure entering the movable cavity 21 and the rodless cavity 13 increases to offset a part of the suddenly increased external load; At the same time, when the oil pressure used to offset the external load increases to exceed the set pressure of the first relief valve 40, or the second relief valve 41, or the third relief valve 42, the corresponding relief valve orifice opens to relieve pressure to prevent pressure shock in the system.

[0032] In another embodiment, when the piston rod retracts, in the heavy-duty driving condition without impact load, the steps are as follows: S1: The rotation speed of the motor 2 is reduced by the speed reducer 3 and then drives the lead screw 11 to rotate. The lead screw 11 drives the lead screw nut 14 to move backward; S2: The lead screw nut 14 moves, driving the piston 15, the piston rod 20, and the piston rod end cover 32 to move backward as a whole. When the piston rod end cover 32 moves backward, it will squeeze the disc spring group 30 on the left side; S3: When the entire piston rod 20 retracts, the switching valve 45 cuts off the function of the accumulator 46; S4: The servo motor 47 in the hydraulic system rotates, driving the variable displacement pump 48 to output oil into the rod chamber 19: the reversing valve 43 switches to the right, and when the hydraulic oil enters the rod chamber 19 through the second oil path, part of the oil enters the rod chamber 19 to push the piston 15 to retract, and the other part enters the closed chamber 31 through the one-way valve 44, acting on the left side of the small piston rod ear 36 and forcing the small piston rod ear 36 to retract; During the process of the piston rod 20 extending and retracting, when the load suddenly increases, the buffering process is as follows: The left disc spring assembly 30 is squeezed again, the retraction speed of the small piston rod ear 36 slows down, and the oil in the closed chamber 31 and the rod chamber 19 is compressed to relieve part of the suddenly increased external load; At the same time, the force sensor 39 transmits the signal to the controller 1, which controls the motor 2 to reduce its speed and increase the torque to increase the bearing capacity of the screw 11 and reduce the impact. At the same time, the controller 1 synchronously controls the servo motor 47 to drive the variable displacement pump 48 to increase the inclination angle and the displacement, thereby increasing the oil pressure entering the closed chamber 31 and the rod chamber 19 to offset part of the sudden increase in external load; At the same time, when the oil pressure used to offset the external load increases to exceed the set pressure of the first relief valve 40, the second relief valve 41, or the third relief valve 42, the corresponding relief valve port opens to release pressure to prevent pressure shock in the system.

[0033] Steps S1-S4 are performed sequentially. In S4, the piston 15 is driven by both electric and hydraulic forces, while the small piston rod lug 36 is driven only by hydraulic force. Therefore, the disc spring assembly 30 is compressed by an amount equal to the electric force, completing one reciprocating motion of the heavy-duty electric cylinder. Therefore, the disc spring assembly 30 on either side of the small piston rod lug 36 is only compressed by the electric force and is not fully compressed, providing space for subsequent impact loads.

[0034] The above processes occur simultaneously. During the entire movement process, because electric drive operates faster than hydraulic drive, the disc spring assembly 30 can prolong the duration of the impact load. When the impact load acts on the disc spring assembly 30, the disc spring assembly 30 will be compressed. Compression takes time, and the hydraulic system fully utilizes this compression time to quickly increase the oil pressure to offset the impact load. Because of the presence of oil pressure, the disc spring assembly 30 will not be fully compressed. Compared with other patents that simply use springs as buffer components, the electro-hydraulic coordinated drive allows the disc spring assembly 30 to provide pressure accumulation time for the hydraulic oil, while the hydraulic pressure protects the disc spring assembly 30 from complete compression. This fully utilizes the advantages of each component to meet the requirements of the electric cylinder's ability to drive heavy loads and possess impact resistance.

[0035] In the above embodiments, on the basis of the original structure of the electric cylinder, a hydraulic system is incorporated into it, and the piston 15 and the piston rod 20 are designed to be hollow. By designing the oil passage hole 16 of the piston 15, the oil fluid can flow quickly, providing convenient conditions for the hydraulic auxiliary drive. It can not only solve the problem that the electric cylinder is difficult to drive heavy loads, but also has a high degree of integration.

[0036] At the same time, the traditional ear lift at the tail of the piston rod 20 is designed as a small piston rod ear lift 36, and the small piston rod ear lift 36 can reciprocate in the piston rod 20. Disc springs are assembled on the moving path, which not only has a buffering effect, but also provides time for the hydraulic oil to accumulate pressure, solving the serious impact caused by the lack of a buffering mechanism when the electric cylinder is subjected to impact loads due to rigid connection. By reasonably utilizing the disc spring and the hydraulic system, which affect each other, the solution can simultaneously have the heavy load capacity and the buffering mechanism, and is applicable to different working conditions.

[0037] It should be understood that the above are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention.

[0038] The above introduction to the drawings used in the embodiments only shows some embodiments of the present invention and should not be regarded as a limitation of the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

Claims

1. A heavy-duty electric cylinder with anti-shock characteristics based on a hydraulic buffer mechanism, comprising a motor, a controller connected to the motor, and a reduction mechanism connected to the output shaft of the motor, wherein the output shaft of the reduction mechanism is connected to a lead screw; characterized in that, Further included are: a hydraulic system and a cylinder barrel; a piston, a piston rod and a lead screw nut connected to the lead screw are arranged inside the cylinder barrel, and the lead screw nut is connected to the piston, and the piston is connected to the piston rod; the inside of the piston rod is hollow to form a moving cavity for the lead screw to move; the piston is adapted to divide the inside of the cylinder barrel into a rod chamber and a rodless chamber that are isolated from each other, and an oil through hole communicating the rodless chamber and the moving cavity is arranged on the piston; the hydraulic system is provided with a first oil passage communicating with the rodless chamber and a second oil passage connected to the rod chamber; the first oil passage and the second oil passage are connected to an oil supply system through a reversing valve, and the oil supply system is adapted to supply oil to the rodless chamber or the rod chamber to increase the oil pressure in the corresponding chamber to counteract part of the impact load borne by the piston rod; a piston rod end cover is arranged at the outer end of the piston rod, and a small piston rod ear hanger is arranged on the piston rod end cover; wherein, the small piston rod ear hanger includes a load connection part, a piston part and a connecting shaft connecting the piston part and the load connection part, and the connecting shaft movably penetrates through a through hole on the piston rod end cover; the piston part is movably arranged in the moving cavity and seals the outer end of the moving cavity; disc spring groups sleeved on the connecting shaft are respectively arranged on both sides of the piston rod end cover; when the load connection part bears a heavy load, part of the impact load is buffered through the compression action of the disc spring groups and the compression action of the piston part on the hydraulic oil in the moving cavity.

2. The anti-shock heavy-duty electric cylinder based on the hydraulic buffer mechanism according to claim 1 is characterized in that: a closed cavity is formed between the piston rod end cover and the piston part, the disc spring groups are arranged in the closed cavity, and an accumulator is connected to the closed cavity, and a switching valve is arranged on the accumulator; when the piston rod extends, the switching valve is opened to enable the accumulator to supply oil to the closed cavity, and when the piston rod retracts, the switching valve cuts off the action of the accumulator; the oil supply system is provided with a third oil passage to be connected to the closed cavity, and a check valve is arranged on the third oil passage so that the third oil passage can only make the hydraulic oil be conveyed from the oil supply system to the closed cavity; when the piston rod retracts, the oil supply system is adapted to supply oil to the closed cavity to push the piston part of the small piston rod ear hanger to retract.

3. The anti-shock heavy-duty electric cylinder based on the hydraulic buffer mechanism according to claim 2 is characterized in that: a force sensor connected to the controller is arranged on the small piston rod ear hanger, and the controller is adapted to control the motor to reduce the speed to improve the bearing capacity when the force sensor detects that the external load borne by the small piston rod ear hanger increases, and the oil supply system is adapted to increase the output oil to counteract the impact.

4. The heavy-duty electric cylinder with anti-shock characteristics based on a hydraulic buffer mechanism according to claim 3, characterized in that, the oil supply system includes a servo motor, a variable displacement pump connected to the servo motor and a fuel tank connected to the variable displacement pump, the variable displacement pump is connected to the first oil passage and the second oil passage through a reversing valve, and the third oil passage is connected in parallel to the second oil passage.

5. The heavy-duty electric cylinder with anti-shock characteristics based on a hydraulic buffer mechanism according to claim 4, characterized in that, A first pressure sensor connected to a controller is provided on the first oil circuit, a second pressure sensor connected to the controller is provided on the second oil circuit, a first overflow valve is provided on the first oil circuit, a second overflow valve is provided on the second oil circuit, and a third overflow valve is provided on the third oil circuit. When the oil pressure on the corresponding oil circuit exceeds the set pressure of the corresponding overflow valve, the pressure is released through the corresponding overflow valve to prevent pressure shock in the cavity connected to the corresponding oil circuit.

6. The heavy-duty electric cylinder with anti-shock characteristics based on a hydraulic buffer mechanism according to claim 1, wherein The cylinder also includes a left cylinder cover and a right cylinder cover arranged at both ends. A shaft rotating sealing ring is arranged between the left cylinder cover and the screw rod, and a second Y-shaped sealing ring, a second support ring and a dust ring are arranged in sequence from the inside to the outside between the right end cover and the piston rod; a first support ring is arranged between the outer side of the piston and the inner wall of the cylinder, and a first Y-shaped sealing ring is arranged on both sides of the first support ring; a bidirectional sealing ring is arranged between the outer side of the piston part of the small piston rod ear and the inner wall of the cylinder, and a third support ring is arranged on both sides of the bidirectional sealing ring.

7. The anti-shock heavy-duty electric cylinder based on the hydraulic buffer mechanism according to claim 1 is characterized in that: The piston is connected to the screw nut via bolts; the piston is connected to the piston rod via threads.

8. A control method for a heavy-duty electric cylinder with anti-shock characteristics based on a hydraulic buffer mechanism according to claim 5, characterized in that, Under heavy-duty driving conditions with no shock load, when the piston rod extends, the steps are as follows: S1: The motor speed is reduced by the reduction gearbox to drive the screw to rotate, and the screw drives the screw nut to move forward; S2: The screw nut moves, driving the piston, piston rod and piston rod end cover to move forward. When the piston rod end cover moves forward, it squeezes the disc spring assembly on the right side. S3: When the entire piston rod is extended, the switch valve opens to allow the accumulator to replenish oil into the closed chamber; S4: The rotation of the servo motor in the hydraulic system drives the variable displacement pump to output oil into the rodless cavity: When the hydraulic oil enters the rodless cavity through the first oil circuit, part of it acts on the screw nut and piston, and the other part enters the movable cavity through the oil hole and acts on the left side of the small piston rod ear to drive the small piston rod ear to extend; When the load suddenly increases during the piston rod extension process, the buffering process is as follows: The disc spring group on the right side is squeezed again, the extension speed of the small piston rod ear hanger slows down, and the oil in the active chamber and the rodless chamber is compressed to relieve part of the sudden increase in external load; At the same time, the force sensor transmits the signal to the controller, which controls the motor speed to reduce and increase the torque to increase the bearing capacity of the screw and reduce the impact; At the same time, the controller synchronously controls the servo motor to drive the variable displacement pump to increase the inclination angle and increase the displacement, thereby increasing the oil pressure entering the active chamber and the rodless chamber to offset part of the sudden increase in external load; At the same time, when the oil pressure used to offset the external load increases to exceed the set pressure of the first relief valve, the second relief valve, or the third relief valve, the corresponding relief valve port opens to release pressure to prevent pressure shock in the system.

9. A control method for a heavy-duty electric cylinder with anti-shock characteristics based on a hydraulic buffer mechanism as described in claim 5, characterized in that, When the piston rod is retracted, under heavy-duty driving conditions with no shock load, the steps are as follows: S1: The motor speed is reduced by the reduction gearbox to drive the screw to rotate, and the screw drives the screw nut to move backward; S2: The screw nut moves, driving the piston, piston rod and piston rod end cover to move backward. When the piston rod end cover moves backward, it squeezes the disc spring assembly on the left side. S3: When the entire piston rod retracts, the switching valve cuts off the accumulator function; S4: The rotation of the servo motor in the hydraulic system drives the variable displacement pump to output hydraulic oil into the rod chamber: when the hydraulic oil enters the rod chamber through the second oil path, part of the oil enters the rod chamber to push the piston to retract, and the other part enters the sealed chamber through the one-way valve and acts on the left side of the small piston rod ear hanger to force the small piston rod ear hanger to retract; During the retraction of the piston rod, when the load suddenly increases, the buffering process is as follows: The left disc spring group is squeezed again, the retraction speed of the small piston rod ear hanger slows down, and the hydraulic oil in the sealed chamber and the rod chamber is compressed to relieve part of the suddenly increased external load; At the same time, the force sensor transmits the signal to the controller, and the controller controls the motor speed to decrease, increases the torque to increase the bearing capacity of the lead screw, and slows down the impact effect; At the same time, the controller synchronously controls the servo motor to drive the variable displacement pump to increase the inclination angle and the displacement, so that the oil pressure entering the sealed chamber and the rod chamber increases to offset part of the suddenly increased external load; At the same time, when the oil pressure used to offset the external load increases to exceed the set pressure of the first relief valve, or the second relief valve, or the third relief valve, the corresponding relief valve orifice opens to relieve pressure to prevent pressure shock in the system.

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