Integrated lithium battery pole piece roller press pump control direct drive hydraulic system and control method

Abstract

According to the pump-controlled direct-drive hydraulic system of the integrated lithium battery pole piece roller press and the control method, the real-time position of a hydraulic cylinder can be controlled by regulating and controlling the rotating speed of a servo motor, and under the rolling working condition, the rotating speed of the servo motor is controlled according to the real-time displacement of a piston of a roller hydraulic cylinder; the piston of the hydraulic cylinder can be kept at the target position for a long time, a high-cost servo valve used in the prior art is not needed, throttling loss of the servo valve in the working process is avoided, and the anti-pollution capacity of the system is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of pole piece rolling forming equipment, and in particular relates to an integrated pump-controlled direct-drive hydraulic system and control method for a lithium battery pole piece rolling press. Background Art

[0002] With the rapid development of new energy vehicles and energy storage industries, the requirements for the production precision of pole pieces in lithium battery manufacturing processes are becoming increasingly stringent. As a core quality index, the thickness consistency of pole pieces directly affects the cycle life, energy density, and safety performance of lithium batteries. As a key equipment for pole piece forming, the dynamic precision and stability of the hydraulic control system of the rolling press have become a technical bottleneck restricting the improvement of the yield rate of battery manufacturing.

[0003] The hydraulic control systems of domestic and foreign pole piece rolling presses mainly adopt a valve-controlled cylinder structure. The electro-hydraulic servo valve control system uses an electro-hydraulic servo valve as a control element to achieve high-precision control of the hydraulic cylinder. The system consists of a hydraulic oil source, a servo valve, hydraulic pipelines, sensors, and a controller. Although the control precision of the servo valve control system is very high, due to the throttling loss at the servo valve orifice, the system efficiency is low, the power loss is large, and moreover, the servo valve has poor anti-pollution ability, requires a high level of oil cleanliness, and poses stringent requirements for equipment maintenance, which is not conducive to the operation and maintenance of the equipment. Summary of the Invention

[0004] Based on this, in view of the above technical problems, an integrated pump-controlled direct-drive hydraulic system and control method for a lithium battery pole piece rolling press are provided.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] As the first aspect of the present invention, an integrated pump-controlled direct-drive hydraulic system for a lithium battery pole piece rolling press is provided, which is characterized in that it includes a servo motor, a hydraulic fixed-displacement pump, a two-position four-way electromagnetic reversing valve, and a displacement sensor. The output shaft of the servo motor is connected to the input shaft of the hydraulic fixed-displacement pump. The inlet of the hydraulic fixed-displacement pump is connected to the outlet of the fuel tank. The outlet of the hydraulic fixed-displacement pump is connected to one port of the two-position four-way electromagnetic reversing valve. The remaining three ports of the two-position four-way electromagnetic reversing valve are respectively connected to the oil return port of the fuel tank, the liquid inlet and outlet port of the rodless cavity of the rolling cylinder, and the liquid inlet and outlet port of the rod cavity. The displacement sensor is arranged in the rolling cylinder;

[0007] During the rolling operation, the real-time displacement of the piston of the rolling cylinder is obtained in real time through the displacement sensor, and the real-time displacement is compared with the desired displacement. When the real-time displacement is greater than the desired displacement, the servo motor is controlled to increase the rotation speed. When the real-time displacement is less than the desired displacement, the servo motor is controlled to decrease the rotation speed. When the real-time displacement is equal to the desired displacement, the servo motor is controlled to maintain the current rotation speed.

[0008] As a second aspect of the present invention, there is provided a method for controlling the piston displacement of a roll hydraulic cylinder of the hydraulic system of the first aspect above, characterized in that it includes:

[0009] During the roll pressing operation, the real-time displacement of the piston of the roll hydraulic cylinder is obtained in real time through the displacement sensor, and the real-time displacement is compared with the desired displacement. When the real-time displacement is greater than the desired displacement, the servo motor is controlled to increase the rotational speed. When the real-time displacement is less than the desired displacement, the servo motor is controlled to decrease the rotational speed. When the real-time displacement is equal to the desired displacement, the servo motor is controlled to maintain the current rotational speed.

[0010] The present invention can control the real-time position of the hydraulic cylinder by adjusting the rotational speed of the servo motor. During the roll pressing operation, the rotational speed of the servo motor is controlled according to the real-time displacement of the piston of the roll hydraulic cylinder, so that the piston of the hydraulic cylinder can be kept at the target position for a long time. There is no need to use a high-cost servo valve as in the prior art, avoiding the throttling loss of the servo valve during the working process and improving the anti-pollution ability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a three-dimensional structural schematic diagram of an embodiment of the present application;

[0012] Figure 2 is a connection structural schematic diagram of a fixing plate, a servo motor, a hydraulic fixed-displacement pump and an oil circuit integration block of an embodiment of the present application;

[0013] Figure 3 is a structural schematic diagram of an oil circuit integration block of an embodiment of the present application;

[0014] Figure 4 is a structural schematic diagram of an oil tank of an embodiment of the present application;

[0015] Figure 5 is a schematic diagram of the principle of an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] The following will describe the embodiments of the present invention with reference to the accompanying drawings of the specification. It should be noted that the embodiments involved in this specification are not exhaustive and do not represent the only embodiments of the present invention. The following corresponding embodiments are only for clearly explaining the inventive content of the present invention and do not limit its embodiments. For those of ordinary skill in the art, different forms of changes and modifications can be made on the basis of the description of this embodiment. Any changes or modifications that belong to the technical concept and inventive content of the present invention and are obvious are also within the protection scope of the present invention.

[0017] Such as Figure 5As shown, in practical applications, the number of hydraulic systems in the embodiments of the present application is two, which are used to drive the pistons of two sets of roll cylinders 2 respectively, so that the piston rods thereof rise and fall to drive the rolls 6 to roll the pole piece 5. The two hydraulic systems are controlled by a controller 3 through two servo drivers 4 respectively. The two sets of roll cylinders 2 are respectively used to roll the pole piece 5 on the operation side and the drive side.

[0018] As Figure 1 and Figure 3 shown, the hydraulic system of the embodiments of the present application includes a fixing plate 110, a servo motor 120, a hydraulic fixed-displacement pump 130, an oil circuit integration block 140, an oil tank 150, a high-pressure filter 160, a two-position four-way electromagnetic directional control valve 170, and an LVDT displacement sensor 180.

[0019] As Figure 2 shown, the fixing plate 110 includes a first plate 111 and a second plate 112. The first plate 111 faces the front and back directions and is parallel to the oil inlet and outlet mounting surface (front side plane) of the roll cylinder 2. The second plate 112 is vertically arranged, faces the left and right directions, and is integrally fixed perpendicular to the first plate 111.

[0020] The servo motor 120 has an in-line structure and is arranged in the left and right directions. The end cover is fixed to the right side surface of the second plate 112 by bolts. The hydraulic fixed-displacement pump 130 is a single-direction gear pump and is arranged in the left and right directions. It passes through the second plate 112 from the left and is fixed to the end cover of the servo motor 120 by bolts. The input shaft of the hydraulic fixed-displacement pump 130 is inserted into the shell of the servo motor 120 and is directly connected to its output shaft without a coupling, which is easy to assemble, saves space and cost.

[0021] The oil discharge port of the hydraulic fixed-displacement pump 130 is connected to one end of an oil discharge pipeline 131.

[0022] The rear side surface of the oil circuit integration block 140 is fixed to the oil inlet and outlet mounting surface of the roll cylinder 2 by bolts, and the front side surface is fixed to the first plate 111 by bolts.

[0023] As Figure 3 shown, a first pressure measuring joint 141, a first pressure sensor 142, a direct-acting overflow valve 143, and a first hydraulic pipe joint 144 are installed on the left side surface of the oil circuit integration block 140, a second pressure measuring joint 145, a second pressure sensor 146, a second hydraulic pipe joint 147, and a check valve 148 are installed on the right side surface, and the interior has a first flow channel, a second flow channel, a third flow channel, a fourth flow channel, and a fifth flow channel.

[0024] The first hydraulic pipe joint 144 is connected to the other end of the oil discharge pipeline 131. The first hydraulic pipe joint 144 is connected to the inlet of the first flow channel. The first flow channel is divided into two paths by a one-way valve 148. One path is connected to a direct-acting overflow valve 143, and the other path is connected to one port of a two-position four-way electromagnetic directional valve 170 through a high-pressure filter 160. The remaining three ports of the two-position four-way electromagnetic directional valve 170 are respectively connected to the inlets of the second flow channel, the third flow channel, and the fourth flow channel. The outlet of the second flow channel is connected to a second hydraulic pipe joint 147. The outlets of the third flow channel and the fourth flow channel are respectively connected to the liquid inlet and outlet of the rodless cavity and the liquid inlet and outlet of the rod cavity of the roll hydraulic cylinder 2 through a first pressure sensor 142 and a second pressure sensor 146.

[0025] The first pressure measuring joint 141, the first pressure sensor 142, the second pressure measuring joint 145, and the second pressure sensor 146 are convenient for detecting the pressures in the rodless cavity and the rod cavity of the roll hydraulic cylinder 2.

[0026] The fifth flow channel is connected between the third flow channel and the fourth flow channel, and a throttling and pressure relief device 190 is provided thereon. The throttling and pressure relief device 190 can adopt a damping throat plug, a throttle valve, an overflow valve, etc.

[0027] As Figure 1 shown, the fuel tank 150 is located above the hydraulic fixed-displacement pump 130. The internal oil suction pipeline is connected to the oil outlet through an oil filter. The oil outlet is connected to the oil inlet of the hydraulic fixed-displacement pump 130 through a flange 190. The flange 190 can enhance the oil suction capacity of the hydraulic fixed-displacement pump 130. At the same time, it also plays a role in fixing the fuel tank 140 on the hydraulic fixed-displacement pump 130. The oil return port of the fuel tank 150 is connected to one end of an oil return pipeline 151, and the other end of the oil return pipeline 151 is connected to the second hydraulic pipe joint 147.

[0028] In the above structure, the fuel tank 150, the servo motor 120, and the hydraulic fixed-displacement pump 130 are longitudinally arranged in terms of spatial layout and are integrally installed on the roll hydraulic cylinder 2 through an oil circuit integration block 140, occupying a smaller space volume. At the same time, accessories such as hydraulic valves and pressure sensors are fixedly connected to the oil circuit integration block 140. The oil discharge port of the hydraulic fixed-displacement pump 130 is directly connected to the oil circuit integration block 140 through an oil discharge pipeline 131, and the oil return pipeline 151 of the fuel tank 150 is directly connected to the oil circuit integration block 140. The remaining oil circuits are all integrated in the oil circuit integration block 140, forming an integrated hydraulic system without intermediate pipelines and having a high integration degree.

[0029] As Figure 4As shown in the figure, the upper cover plate of the fuel tank 150 is provided with an air filter 152 and a temperature and liquid level integrated sensor 153. Its rear side plate fixedly mounts a plate cooler 154 through bolts. The plate cooler 154 has a cavity, and this cavity is communicated with the inside of the fuel tank 150 through a pipeline 154a. The oil return port of the fuel tank 150 is formed on the upper surface of the plate cooler 154. Heat dissipation fins can be arranged on the plate cooler 154 to further improve the heat dissipation capacity.

[0030] As Figure 1 shown in the figure, the LVDT displacement sensor 180 is installed on the roll hydraulic cylinder 2 to detect the piston displacement of the roll hydraulic cylinder 2.

[0031] The working principle of the hydraulic system in the embodiment of the present application is as follows:

[0032] As Figure 5 shown in the figure, driven by the servo motor 120, the hydraulic fixed-displacement pump 130 sucks low-pressure oil from the fuel tank 150 and discharges high-pressure oil from its oil discharge port. The high-pressure oil flows from the first hydraulic pipe joint 144 through the first flow path to the one-way valve 148. One way of the high-pressure oil flowing out of the one-way valve 148 flows back to the fuel tank 150 through the direct-acting overflow valve 143. The direct-acting overflow valve 143 plays a safety protection role. Only when the system pressure exceeds the opening pressure of the overflow valve, the high-pressure oil will flow back to the fuel tank through the overflow valve. The other way enters the two-position four-way electromagnetic reversing valve 170 through the high-pressure filter 160.

[0033] During the refueling and rising working condition, the two-position four-way electromagnetic reversing valve 170 is de-energized, and the high-pressure oil enters the rodless cavity of the roll hydraulic cylinder 2, causing the piston of the roll hydraulic cylinder 2 to push the roll upward. Since the roll does not contact the lithium battery pole piece 5 at this stage, the load force is the gravity of the roll, and the pressure difference between the two chambers of the hydraulic cylinder is small, and the oil does not flow through the fifth flow path.

[0034] During the roll pressing working condition, the roll presses the pole piece 5, and the controller 3 controls the rotation speed of the servo motor 120 through the servo driver 4 to realize the position holding of the hydraulic cylinder: the controller 3 obtains the real-time displacement of the piston of the roll hydraulic cylinder 2 in real time through the displacement sensor 180, compares the real-time displacement with the desired displacement. When the real-time displacement is greater than the desired displacement, the rotation speed of the servo motor 120 is increased by control. When the real-time displacement is less than the desired displacement, the rotation speed of the servo motor 120 is decreased by control. When the real-time displacement is equal to the desired displacement, the servo motor is controlled to maintain the current rotation speed.

[0035] After testing, the piston position accuracy of the operating side hydraulic cylinder is basically maintained within ±0.4μm, and the peak error is 0.7μm. The piston position accuracy of the drive side hydraulic cylinder is basically maintained within ±0.3μm, and the peak error is 0.5μm. The long-term position holding effect of the piston of the hydraulic cylinder is good.

[0036] At this stage, the roll hydraulic cylinder 2 bears a large load, and there is a large pressure difference between the two chambers of the roll hydraulic cylinder 2. A small amount of oil is used to supplement the internal leakage of the hydraulic cylinder, and the rest of the oil flows back to the oil tank 150 through the fifth flow channel. Due to the oil discharge of the fifth flow channel, it is possible to avoid the low-speed state of the hydraulic fixed-displacement pump 130 during the roll pressing operation, extend the service life of the hydraulic fixed-displacement pump 130, and at the same time accelerate the circulation of the system oil, which is beneficial to the system heat dissipation.

[0037] During the material change and falling condition, the two-position four-way electromagnetic directional control valve 170 is energized, and the high-pressure oil enters the rod chamber of the roll hydraulic cylinder 2, causing the oil in the non-rod chamber to flow back to the oil tank 150, and the hydraulic cylinder descends.

[0038] As can be seen from the above, the hydraulic system provided by the embodiment of the present application can control the real-time position of the hydraulic cylinder by regulating the rotational speed of the servo motor. During the roll pressing operation, the rotational speed of the servo motor is controlled according to the real-time displacement of the piston of the roll hydraulic cylinder, so that the piston of the hydraulic cylinder can be kept at the target position for a long time. There is no need to use a high-cost servo valve as in the prior art, avoiding the throttling loss of the servo valve during the working process, improving the anti-pollution ability of the system, and overcoming the problems of low system efficiency and large power loss in the prior art.

[0039] At the same time, the system adopts an integrated design, with a simple hydraulic circuit and high integration, reducing the installation cost and the maintenance cost of the equipment.

[0040] In addition, the setting of the fifth flow channel can avoid the low-speed operation of the hydraulic fixed-displacement pump during the rolling process, improve the service life of the hydraulic fixed-displacement pump and accelerate the circulation of the system oil. Combined with the plate cooler of the oil tank, a good heat dissipation effect is achieved, and the reliability of the system is improved.

[0041] Obviously, those of ordinary skill in the art in this technical field should recognize that the above embodiments are only used to illustrate the present invention, rather than to limit the present invention. As long as within the scope of the essential spirit of the present invention, the changes and modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. An integrated lithium battery pole piece roll press pump-controlled direct drive hydraulic system, characterized in that, It includes a servo motor, a hydraulic fixed-displacement pump, a two-position four-way solenoid directional control valve, and a displacement sensor. The output shaft of the servo motor is connected to the input shaft of the hydraulic fixed-displacement pump. The inlet of the hydraulic fixed-displacement pump is connected to the outlet of the fuel tank. The outlet of the hydraulic fixed-displacement pump is connected to one port of the two-position four-way solenoid directional control valve. The remaining three ports of the two-position four-way solenoid directional control valve are respectively connected to the oil return port of the fuel tank, the liquid inlet / outlet port of the rodless cavity of the roll cylinder, and the liquid inlet / outlet port of the rod cavity of the roll cylinder. The displacement sensor is arranged in the roll cylinder; During the roll pressing condition, the real-time displacement of the piston of the roll cylinder is obtained in real time through the displacement sensor. The real-time displacement is compared with the expected displacement. When the real-time displacement is greater than the expected displacement, the servo motor is controlled to increase the rotational speed. When the real-time displacement is less than the expected displacement, the servo motor is controlled to decrease the rotational speed. When the real-time displacement is equal to the expected displacement, the servo motor is controlled to maintain the current rotational speed.

2. The integrated lithium battery pole piece roll press pump-controlled direct-drive hydraulic system according to claim 1, wherein It further includes an oil circuit integration block. The oil circuit integration block has a first flow channel, a second flow channel, a third flow channel, and a fourth flow channel. The servo motor, the hydraulic fixed-displacement pump, the oil circuit integration block, and the fuel tank are integrally fixed on the installation surface of the inlet and outlet of the roll cylinder. The outlet of the hydraulic fixed-displacement pump is connected to one port of the two-position four-way solenoid directional control valve through an oil discharge pipeline and the first flow channel. The remaining three ports of the two-position four-way solenoid directional control valve are respectively connected to the oil return port of the fuel tank, the liquid inlet / outlet port of the rodless cavity of the roll cylinder, and the liquid inlet / outlet port of the rod cavity of the roll cylinder through the second flow channel, the third flow channel, and the fourth flow channel.

3. An integrated lithium battery pole piece roll press pump-controlled direct drive hydraulic system according to claim 2, characterized in that, The servo motor is connected to the oil circuit integration block through a fixing plate. The hydraulic fixed-displacement pump is fixed to the end cover of the servo motor by bolts. The output shaft of the servo motor is directly connected to the input shaft of the hydraulic fixed-displacement pump. The oil circuit integration block is connected to the installation surface of the inlet and outlet through bolts.

4. An integrated lithium battery pole piece roll press pump-controlled direct drive hydraulic system according to claim 3, characterized in that, The fixing plate includes a first plate parallel to the installation surface of the inlet and outlet and a second plate vertically fixed to the first plate. The second plate is arranged vertically. The first plate is fixed to the oil circuit integration block by bolts. The servo motor is vertically fixed to the second plate by bolts.

5. An integrated lithium battery pole piece roll press pump-controlled direct drive hydraulic system according to claim 3, characterized in that, The fuel tank is located above the hydraulic fixed-displacement pump. The inlet of the hydraulic fixed-displacement pump is connected to the outlet of the fuel tank through a flange.

6. The integrated lithium battery pole piece roll press pump-controlled direct drive hydraulic system according to claim 2, wherein, The first flow channel is connected to the two-position four-way solenoid directional control valve through a check valve and a high-pressure filter. The outlets of the third flow channel and the fourth flow channel are respectively connected to the liquid inlet / outlet port of the rodless cavity of the roll cylinder and the liquid inlet / outlet port of the rod cavity of the roll cylinder through a pressure sensor.

7. An integrated lithium battery pole piece roll press pump-controlled direct drive hydraulic system according to claim 2, characterized in that, The oil circuit integration block further has a fifth flow channel. The fifth flow channel is connected between the third flow channel and the fourth flow channel, and is provided with a throttling and pressure relief device.

8. An integrated lithium battery pole piece roll press pump-controlled direct drive hydraulic system according to claim 7, characterized in that, The throttling and pressure relief device adopts a damping choke plug, a throttle valve, or an overflow valve.

9. The integrated lithium battery pole piece roll press pump-controlled direct drive hydraulic system according to claim 1, characterized in that, The upper cover plate of the fuel tank is provided with an air filter, a temperature and liquid level integrated sensor, and a plate cooler.

10. A method for controlling the piston displacement of the roll hydraulic cylinder of an integrated lithium battery pole piece roll press pump-controlled direct drive hydraulic system according to any one of claims 1-9, characterized in that, It includes: During the roll pressing operation, the real-time displacement of the piston of the roll hydraulic cylinder is obtained in real time through the displacement sensor, and the real-time displacement is compared with the desired displacement. When the real-time displacement is greater than the desired displacement, the servo motor is controlled to increase the rotational speed. When the real-time displacement is less than the desired displacement, the servo motor is controlled to decrease the rotational speed. When the real-time displacement is equal to the desired displacement, the servo motor is controlled to maintain the current rotational speed.

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