Novel electro-hydraulic composite driving system

Abstract

The invention relates to the technical field of industrial executing mechanisms, and particularly discloses a novel electro-hydraulic composite driving system which comprises an electric part, a hydraulic control part, a cylinder body assembly and a piston rod assembly. The electric part comprises an electric part motor, a speed reducer, a gearbox assembly, a gear transmission pair, an encoder assembly, a lead screw transmission pair assembly and a piston locking nut. The hydraulic control part comprises a main electromagnetic reversing valve, an overflow valve, a first oil tank, an energy accumulator, a first electromagnetic two-position reversing valve, a bidirectional hydraulic lock, a bidirectional hydraulic pump, a hydraulic control part motor, a balance valve, a second electromagnetic two-position reversing valve, a second oil tank and a stop valve. The novel electro-hydraulic composite driving system has the large bearing advantage of a hydraulic cylinder and the high-precision characteristic of an electric cylinder, the adaptive scene of an executing mechanism is expanded, and the safety, reliability and high efficiency of operation of industrial equipment are improved.

Description

Technical Field

[0001] This invention relates to the field of industrial actuator technology, specifically a novel electro-hydraulic hybrid drive system. Background Technology

[0002] Actuators are core components in modern industry that realize mechanical motion and power output, and their performance directly determines the operating quality and efficiency of industrial equipment. With the improvement of industrial automation, higher requirements are placed on the precision, load capacity, reliability, and adaptability of actuators.

[0003] In existing technologies, hydraulic cylinders, as mature actuators, transmit pressure energy through hydraulic oil and have the advantages of large thrust and large load capacity. However, they are prone to creeping under low-speed and heavy-load conditions, resulting in poor positioning and control accuracy, which limits their application in high-precision scenarios. Electric cylinders convert electrical energy into linear motion through motors and transmission mechanisms, offering high positioning accuracy and fast response speed. However, their load capacity is limited, making them difficult to adapt to high-load conditions.

[0004] To integrate the advantages of both, preliminary research on electro-hydraulic hybrid drive has been carried out in related fields. However, existing technologies have obvious defects: some solutions separate or simply splice the hydraulic cylinder and electric cylinder, failing to achieve integrated core components; the working mode is singular, unable to flexibly adapt to different loads and precision requirements; the replenishment and discharge of the working medium in the cylinder during piston rod extension and retraction are not fully considered, posing a risk of oil leakage, resulting in insufficient safety and reliability, and making it difficult to meet the actual needs of high efficiency and rapid output in the industrial field.

[0005] Therefore, designing a novel multi-mode, highly reliable, and compact electro-hydraulic hybrid drive system has significant application value. Summary of the Invention

[0006] The purpose of this invention is to provide a novel electro-hydraulic hybrid drive system to solve the problems of traditional hydraulic cylinders being prone to crawling under low speed and heavy load, having low positioning accuracy, and electric cylinders having limited load capacity.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a novel electro-hydraulic hybrid drive system, comprising: an electric part, a hydraulic control part, a cylinder assembly, and a piston rod assembly; The electric component includes an electric motor, a reducer, a gearbox assembly, a gear transmission pair, an encoder assembly, a lead screw transmission pair assembly, and a piston lock nut. The hydraulic control section includes a main solenoid directional valve, a relief valve, a first oil tank, an accumulator, a first solenoid two-position directional valve, a two-way hydraulic lock, a two-way hydraulic pump, a hydraulic control section motor, a balance valve, a second solenoid two-position directional valve, a second oil tank, and a shut-off valve. The piston locking nut is fixed to the piston rod assembly near the piston end through a radial hole. The piston rod assembly has a cylindrical hollow section in the middle that is adapted to the lead screw drive assembly. The cylinder assembly has an oil inlet and an oil outlet at both ends.

[0008] In a novel electro-hydraulic hybrid drive system according to an embodiment of the present invention, the main electromagnetic directional valve switches between three working modes—electric drive, hydraulic drive, and hybrid drive—by switching positions and coordinating with the start and stop states of the electric motor and the hydraulic motor. The encoder assembly is connected to the lead screw drive assembly, and the balance valve is connected in series in the oil circuit between the main solenoid directional valve and the cylinder assembly.

[0009] In a novel electro-hydraulic composite drive system according to an embodiment of the present invention, in the electric drive mode, the main electromagnetic reversing valve switches to the right position, so that the front and rear cover oil ports of the cylinder assembly are connected and the oil in the rod chamber and the rodless chamber are interconnected. When the hydraulic control motor is powered off, it stops. The power output from the electric motor is transmitted sequentially through the reducer, gear transmission pair, and lead screw transmission pair assembly to the piston rod assembly, driving its extension and retraction. The second electromagnetic two-position directional valve works in conjunction with the second oil tank to replenish and discharge oil in the oil circuit, and the encoder assembly detects the position of the piston rod assembly in real time.

[0010] In a novel electro-hydraulic hybrid drive system according to an embodiment of the present invention, in the hydraulic control drive mode, the main electromagnetic reversing valve switches to the left position, the electric motor starts and only provides the basic force for the rotation of the gear transmission pair, without bearing the load. The motor of the hydraulic control section starts and drives the bidirectional hydraulic pump to operate. The high-pressure oil generated enters the corresponding chamber of the cylinder assembly through the bidirectional hydraulic lock and balance valve, pushing the piston rod assembly to extend and retract. The accumulator replenishes oil to the oil circuit through a shut-off valve, and excess oil flows back to the first oil tank through an overflow valve. The first electromagnetic two-position reversing valve controls the oil replenishment action of the accumulator.

[0011] In a novel electro-hydraulic hybrid drive system according to an embodiment of the present invention, in the hybrid drive mode, the electric part and the hydraulic control part operate in coordination, and the speed v1 of the hydraulic control drive driving the piston rod assembly alone and the speed v2 of the electric drive driving the piston rod assembly alone satisfy v1≤v2. The speed and direction of the piston rod assembly are controlled by the electric component, while the load-bearing capacity of the system is provided by the hydraulic component.

[0012] In a novel electro-hydraulic hybrid drive system according to an embodiment of the present invention, an air filter is provided inside the cylinder assembly. The air filter is used to compensate for the gas volume difference generated between the rod chamber and the rodless chamber of the cylinder assembly when the piston rod assembly extends or retracts.

[0013] In a novel electro-hydraulic hybrid drive system according to an embodiment of the present invention, the oil inlet of the second electromagnetic two-position directional valve is connected to the second oil tank, and the oil outlet is connected to the connecting oil circuit between the rod chamber and the rodless chamber of the cylinder assembly, for oil replenishment and discharge in electric drive mode.

[0014] In a novel electro-hydraulic hybrid drive system according to an embodiment of the present invention, the accumulator is connected to the oil inlet side of the bidirectional hydraulic lock via a shut-off valve, and the first electromagnetic two-position directional valve is connected in parallel to the inlet of the accumulator.

[0015] In a novel electro-hydraulic hybrid drive system according to an embodiment of the present invention, the lead screw transmission pair assembly includes a lead screw, a rotary sealing assembly, a bushing, a key, a gear locking nut, and an encoder connecting shaft; The right end of the lead screw is fixed to the driven gear of the gear transmission pair, and the protruding part of the lead screw shaft is connected to the shaft hole of the encoder assembly.

[0016] In a novel electro-hydraulic hybrid drive system according to an embodiment of the present invention, the output end of the motor of the electric part is fixedly connected to the input end of the reducer and constitutes a power transmission unit, and the output end of the reducer is fixedly connected to the driving gear of the gear transmission pair.

[0017] Compared with the prior art, the beneficial effects of the present invention are: This novel electro-hydraulic hybrid drive system: 1. It integrates the core advantages of hydraulic cylinders (high thrust and high load capacity) and electric cylinders (fast response and high precision). By flexibly switching between electric, hydraulic, and hybrid drive modes, it adapts to various working conditions such as no-load, light-load, heavy-load, and high-precision, thus solving the problem of poor adaptability of a single actuator.

[0018] 2. Focusing on the oil circuit design, the air filter compensates for changes in gas volume. The accumulator, together with the first and second solenoid two-position directional valves, completes the oil replenishment and discharge in different modes, effectively solving the problem of insufficient working medium or leakage. Components such as the balance valve and relief valve ensure stable oil circuit pressure, reduce the risk of system failure, and meet the safety requirements of industrial fields.

[0019] 3. The system adopts a symmetrical layout of hydraulic and electric components. After modeling and optimization, the system size and complexity are significantly reduced, space utilization is improved, and industrial equipment integration and installation are facilitated. Attached image description: Figure 1This is a schematic diagram of a novel electro-hydraulic hybrid drive system provided in an embodiment of this application; Figure 2 This is a schematic diagram of the partially disassembled structure of the present invention; Figure 3 This is a partial side sectional view of the present invention.

[0020] In the picture: 1. Electric motor; 2. Reducer; 3. Gearbox assembly; 4. Gear drive pair; 5. Encoder assembly; 6. Lead screw drive pair assembly; 7. Piston lock nut; 8. Cylinder assembly; 9. Piston rod assembly; 10. Main solenoid directional valve; 11. Relief valve; 12. First oil tank; 13. Accumulator; 14. First solenoid two-position directional valve; 15. Two-way hydraulic lock; 16. Two-way hydraulic pump; 17. Hydraulic control motor; 18. Balance valve; 19. Second solenoid two-position directional valve; 20. Second oil tank. Detailed Implementation

[0021] 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.

[0022] Example 1: Please see Figure 1-3 The novel electro-hydraulic hybrid drive system of the present invention includes an electric motor 1, a reducer 2, a gearbox assembly 3, a gear transmission pair 4, an encoder assembly 5, a lead screw transmission pair assembly 6, a piston locking nut 7, a cylinder assembly 8, a piston rod assembly 9, a main solenoid directional valve 10, an overflow valve 11, a first oil tank 12, an accumulator 13, a first solenoid two-position directional valve 14, a bidirectional hydraulic lock 15, a bidirectional hydraulic pump 16, a hydraulic control motor 17, a balance valve 18, a second solenoid two-position directional valve 19, and a second oil tank 20.

[0023] Among them, the piston locking nut 7 is fixed to the piston rod assembly 9 near the piston end through the radial hole, which is used to realize the fixed connection between the piston rod assembly 9 and the screw drive pair assembly 6 nut. The piston rod assembly 9 has a cylindrical hollow section in the middle that is adapted to the screw drive pair assembly 6, so that the screw can be nested inside the piston rod assembly 9, realizing the compact design of the structure, while ensuring that the operation of the screw drive pair assembly 6 can drive the piston rod assembly 9 to perform linear extension and retraction. The right end of the lead screw of the lead screw drive assembly 6 is fixed to the driven gear of the gear drive assembly 4, and the protruding part of the shaft end is connected to the hinged shaft hole of the encoder assembly 5. The outer shell of the encoder assembly 5 is fixed to the outer shell of the gearbox assembly 3. The lead screw drive assembly 6 consists of a lead screw, a rotary seal assembly, a bushing, a key, a gear lock nut, and an encoder connecting shaft. The lead screw is a high-precision ball screw. The rotary seal assembly is fitted onto the end of the lead screw shaft to achieve sealing. The bushing provides support and guidance for the lead screw. The key fixes each component circumferentially. The gear lock nut locks the connection between the lead screw and the driven gear. The encoder connecting shaft connects the lead screw and the encoder assembly 5. The encoder assembly 5 can detect the rotation angle of the lead screw in real time, and then calculate the extension and retraction displacement of the piston rod assembly 9 to ensure synchronous and accurate position detection. Cylinder assembly 8 and piston rod assembly 9 form a sliding pair; the bottom of gearbox assembly 3 is connected to the rear cover of cylinder assembly 8; an air filter (attached) is embedded inside cylinder assembly 8. Figure 3 (g) The air filter is specifically embedded in the pre-set mounting hole on the top of the cylinder head of the cylinder block assembly 8. Its structure adopts an integrated design of "outer shell, filter element, and vent valve". The outer shell is a cylindrical structure adapted to the cylinder head mounting hole, and is embedded in the mounting hole and fixed to the cylinder head using a threaded sealing method. The filter element is made of high-precision non-woven fabric and is used to filter the outside air entering the cylinder and prevent impurities from entering. This air filter is connected to the internal chamber of the cylinder block and is used to compensate for the gas volume difference generated between the rod chamber and the rodless chamber when the piston rod assembly 9 extends and retracts (according to the appendix). Figure 3 As shown, in cylinder block assembly 8, e is the rodless chamber and f is the rod chamber, and its ventilation principle is as follows: When the piston rod assembly 9 extends or retracts, the rod chamber of the cylinder assembly 8 (attached) Figure 3 The volumes of the rodless chamber (e chamber) and the rodless chamber (f chamber) change in opposite directions. When the volume of the rodless chamber increases, a negative pressure is formed inside. At this time, outside air enters the rodless chamber after being filtered by the filter element, compensating for the gas volume difference in the rodless chamber. When the volume of the rodless chamber decreases, a positive pressure is formed inside. Excess air in the rodless chamber is filtered by the filter element and discharged to the outside, thereby balancing the internal air pressure of the cylinder, avoiding abnormal pressure in the chamber, and preventing external impurities from entering. The electric motor 1 and the reducer 2 form a closely matched power transmission combination. The right end of the reducer 2 is connected to the drive gear of the gear transmission pair 4. The left end of the reducer 2 mounting base is fixed to the motor reducer, and the right end is fixed to the bottom of the gearbox assembly 3.

[0024] Among them, the left port of the main solenoid directional valve 10 is connected in sequence to the balance valve 18, the overflow valve 11, the left side of the bidirectional hydraulic lock 15 and the left port of the bidirectional hydraulic pump 16, and the right port is connected to the balance valve 18 and connected to the rodless chamber oil circuit; the right end of the bidirectional hydraulic pump 16 is connected to the right side of the bidirectional hydraulic lock 15, and the oil circuit is connected in series with the overflow valve 11 and the first oil tank 12. The intermediate oil circuit of the two-way hydraulic lock 15 is connected to the accumulator 13 through a shut-off valve, and the first electromagnetic two-position directional valve 14 is installed in conjunction with the accumulator 13. The second electromagnetic two-position directional valve 19 is connected to the connecting oil circuit between the rod chamber and the rodless chamber, and is also connected to the second oil tank 20. Here, it is necessary to clarify the functional division of the two oil tanks to avoid confusion: the first oil tank 12 is the main oil supply tank, which is mainly used for the storage, circulation and replenishment of the main oil circuit in the hydraulic control drive mode and the hybrid drive mode, to ensure the oil supply required for the operation of the bidirectional hydraulic pump 16, and at the same time to receive the excess oil returned by the overflow valve 11, so as to maintain the oil balance and cleanliness of the main oil circuit; the second oil tank 20 is an auxiliary oil replenishment tank, which is only used in the electric drive mode. In conjunction with the second electromagnetic two-position directional valve 19, it replenishes or drains the oil volume difference generated between the rod chamber and the rodless chamber of the cylinder assembly 8 when the piston rod assembly 9 extends and retracts, and does not participate in the oil circulation of the main oil circuit.

[0025] In this embodiment, the specific connection pipeline layout of each component is as follows: the left port of the main solenoid directional valve 10 is sequentially connected to the balance valve 18, the overflow valve 11, the left side of the bidirectional hydraulic lock 15 and the left port of the bidirectional hydraulic pump 16, and the right port is connected to the balance valve 18 and connected to the rodless chamber oil circuit. By switching the position of the main solenoid directional valve 10, the oil circuit can be reversed, and then, in conjunction with the start and stop states of the electric motor 1 and the hydraulic control motor 17, the switching of the three drive modes can be completed. The right end of the bidirectional hydraulic pump 16 is connected to the right side of the bidirectional hydraulic lock 15. The oil circuit is connected in series with the overflow valve 11 and the first oil tank 12. The overflow valve 11 can monitor the oil circuit pressure in real time. When the oil circuit pressure exceeds the set value, the overflow valve 11 opens and introduces the excess oil into the first oil tank 12 (the main oil circuit supply tank) to achieve overflow protection and prevent the hydraulic components from being damaged by excessive oil circuit pressure. The intermediate oil circuit of the two-way hydraulic lock 15 is connected to the accumulator 13 through the shut-off valve. The first electromagnetic two-position directional valve 14 is installed in conjunction with the accumulator 13 to control the oil replenishment action of the accumulator 13. When the oil in the oil circuit is insufficient, the accumulator 13 releases oil through the shut-off valve to replenish the oil circuit, ensuring that the oil circuit has sufficient oil and stable pressure. The second electromagnetic two-position directional valve 19 is connected to the oil circuit connecting the rod chamber and the rodless chamber, and is connected to the second oil tank 20 (auxiliary oil replenishment and discharge tank). In electric drive mode, it is used to replenish and discharge oil according to the oil volume change in the rod chamber and the rodless chamber, so as to ensure the oil circuit oil balance.

[0026] The specific working process of this invention is as follows: First, electric drive mode: the main solenoid directional valve 10 is connected to the right port, the oil ports of the front and rear covers of the cylinder block assembly 8 are connected, and the oil in the rod chamber and the rodless chamber are interconnected. The hydraulic control motor 17 is not powered. After the electric motor 1 is started, it drives the drive wheel of the gear transmission pair 4 to rotate through the reducer 2. The drive wheel drives the driven wheel and the lead screw transmission pair assembly 6 to rotate, which in turn drives the piston rod assembly 9 to move. The encoder assembly 5 detects the position of the piston rod assembly 9 in real time and synchronously feeds back the load signal. The system dynamically fine-tunes the current command to avoid overload or insufficient torque. The air filter compensates for changes in gas volume. The second electromagnetic two-position directional valve 19 replenishes or discharges oil from the second oil tank 20 (auxiliary oil replenishment and discharge tank) according to the oil changes in the rod chamber and the rodless chamber, ensuring the oil balance in the electric drive mode and clearly distinguishing it from the main oil circulation function of the first oil tank 12 (main oil supply tank).

[0027] Secondly, in the hydraulic drive mode: the main solenoid directional valve 10 is connected to the left port, and the electric motor 1 only provides the basic force for gear rotation and does not bear the load; when the hydraulic motor 17 rotates forward, it drives the bidirectional hydraulic pump 16 to rotate forward, and the rodless chamber oil circuit forms high pressure oil, which opens the left side of the bidirectional hydraulic lock 15 and enters the rodless chamber through the balance valve 18 to push the piston rod assembly 9 out. At this time, due to the extension of the piston rod assembly 9, a space difference occurs between the rod chamber and the rodless chamber. The accumulator 13 releases oil through the shut-off valve to replenish the oil circuit. The first electromagnetic two-position reversing valve 14 assists in controlling the replenishment flow rate, and the oil in the rod chamber flows back to the oil circuit. When the hydraulic control motor 17 reverses, high-pressure oil is formed in the rod chamber, which opens the right side of the bidirectional hydraulic lock 15. Oil in the rodless chamber flows back, some of which is added to the accumulator 13, and the rest enters the oil circuit for circulation. The piston rod assembly 9 retracts, and the overflow valve 11 monitors the oil circuit pressure in real time. When the pressure is over-pressurized, the oil is introduced into the first oil tank 12 to achieve overflow protection.

[0028] Finally, the hybrid drive mode: This mode is suitable for operation under heavy load and high precision conditions, and can take into account the system's load-bearing capacity and positioning accuracy. At this time, the main solenoid directional valve 10 switches to the left position, and the electric part and the hydraulic part work together to achieve coordinated power output. The speed v1 of the hydraulically driven piston rod assembly 9 and the speed v2 of the electrically driven piston rod assembly 9 satisfy the speed relationship v1≤v2. Here, v1 is the maximum extension speed that the hydraulically driven part can achieve when working alone, which is determined solely by the hydraulic power of the hydraulic system and is used to ensure that the hydraulically driven part can stably provide heavy load-bearing capacity. v2 is the extension speed that the electrically driven part can achieve when working alone, which is determined by the speed control of the electric motor and is used to achieve precise control of the speed and direction of the piston rod assembly. The limitation of v1≤v2 can avoid the hydraulically driven part from being unable to accurately synchronize with the electric part due to excessive speed, prevent motion interference between the electric and hydraulic parts, and ensure that the electric part can always "pull" or "match" the movement rhythm of the hydraulic part. This allows the hydraulic part to fully utilize its high load-bearing capacity advantage, while the high-precision speed control of the electric part enables precise control of the overall movement speed of the piston rod assembly. In this mode, the speed and direction of the piston rod assembly 9 are controlled by the electric part. Specifically, by adjusting the speed of the electric motor 1, the operating speed of the lead screw transmission pair assembly 6 is controlled, thereby precisely controlling the extension and retraction speed and direction of the piston rod assembly 9. The encoder assembly 5 provides real-time feedback on the position information of the piston rod assembly 9, forming a closed-loop control to ensure positioning accuracy. The system's load-bearing capacity is provided by the hydraulic control section, which outputs high-pressure oil through a bidirectional hydraulic pump 16 to provide sufficient thrust for the piston rod assembly 9, adapting to the needs of heavy-duty conditions. At the same time, the balance valve 18 in the oil circuit maintains stable pressure to prevent pressure changes caused by load fluctuations. The overflow valve 11 works with the first oil tank 12 to achieve overload protection. The first electromagnetic two-position directional valve 14 assists in adjusting the oil replenishment state according to the oil circuit demand. The accumulator 13 replenishes the oil circuit in real time. The second electromagnetic two-position directional valve 19 works with the second oil tank 20 to ensure oil balance. The air filter compensates for gas volume differences. All components work together to ensure stable and efficient operation in the hybrid drive mode.

[0029] It should be noted that the electric motor adopts a torque / current dual closed-loop control strategy to achieve adaptive switching of torque / current under different driving modes. The specific switching logic is as follows: First, a trigger signal is required when switching modes. The position switching signal of the main solenoid directional valve is used as the core trigger signal. It is combined with the start and stop status of the hydraulic control motor and the load feedback signal of the piston rod assembly detected by the encoder assembly (which is calculated through the force of the lead screw drive assembly) to form a linkage trigger mechanism for mode switching, ensuring accurate switching timing and avoiding erroneous switching. Secondly, the torque / current control in electric drive mode is as follows: In electric drive mode, the electric motor needs to bear the entire load driving force. At this time, the system sets the torque command of the electric motor to 80%-90% of the maximum rated torque (leaving a torque margin of 10%-20% to cope with load fluctuations). The current command is synchronously matched with the torque demand, and the current closed-loop control is adopted to ensure stable torque output. At the same time, the encoder component provides real-time feedback on the displacement and speed signals of the piston rod assembly. Combined with the load feedback signal, the current command is dynamically fine-tuned to avoid jamming or stalling caused by motor overload or insufficient torque, and to ensure smooth extension and retraction of the piston rod assembly. Next, the torque / current control in the hydraulic drive mode is as follows: In the hydraulic drive mode, the electric motor only needs to provide the basic force for the rotation of the gear transmission pair and does not bear the load. At this time, the system sets the torque command of the electric motor to 10%-15% of the maximum rated torque, which is only used to overcome the mechanical friction resistance of the gear transmission pair and the lead screw transmission pair components to ensure smooth operation of the transmission components. The corresponding current command is synchronously reduced to a low current threshold (only to maintain the motor running at a low speed and smoothly) to avoid excessive energy consumption of the motor when it is idling, and at the same time to prevent the motor output torque from interfering with the drive action of the hydraulic control part. Next, the torque / current control in the hybrid drive mode is as follows: In the hybrid drive mode, the electric motor mainly controls the speed and direction of the piston rod assembly and does not bear the main load. At this time, the torque command is set to 20%-30% of the maximum rated torque, and the current command matches this torque requirement, ensuring that the electric part can accurately control the operating speed of the screw drive assembly, thereby controlling the motion state of the piston rod assembly. At the same time, the system collects the oil circuit pressure signal of the hydraulic control part in real time (reflecting the load size) and dynamically fine-tunes the torque / current of the electric motor to ensure that the speed relationship v1≤v2 is stable and avoids motion interference between the electric part and the hydraulic control part. Finally, during mode switching, a gradual transition strategy is adopted to avoid system shock caused by sudden changes in torque / current. 50ms before switching, the system begins to gradually adjust the torque / current command of the electric motor. During the switching process, the motor speed, torque, current feedback signals, as well as the feedback signals of the encoder component and oil circuit pressure are collected in real time, and the transition rate is adjusted in a closed loop. After the switching is completed, the current torque / current command is maintained stable for 300ms. After confirming that the system is running smoothly, it switches to normal control logic.

[0030] In this embodiment, the various components of the system work together, demonstrating the technical advantages of the present invention: by flexibly switching between electric, hydraulic, and hybrid drive modes, it can adapt to various working conditions such as no-load, light-load, heavy-load, and high-precision, thus solving the problem of poor adaptability of a single actuator in various scenarios. Focusing on the oil circuit design, the air filter compensates for changes in gas volume, and the accumulator works with the first electromagnetic two-position directional valve 14 and the second electromagnetic two-position directional valve 19 to complete the oil replenishment and discharge in different modes, effectively solving the problem of insufficient working medium or leakage. Components such as the balance valve 18 and the overflow valve 11 ensure stable oil circuit pressure, reduce the risk of system failure, and meet the safety requirements of the industrial field. The hydraulic and electric parts are symmetrically arranged, and after modeling optimization, the system volume and complexity are significantly reduced, the space utilization is improved, and the integration and installation of industrial equipment is facilitated.

[0031] Example 2: This embodiment applies a novel electro-hydraulic hybrid drive system to the feed actuator of a high-precision, heavy-duty CNC machine tool. Addressing the core multi-condition requirements of "rapid positioning under no-load, high-speed feed under light load, and high-precision cutting under heavy load" during CNC machining, the system achieves both machining efficiency and accuracy through adaptive switching of drive modes. The system component configuration is consistent with Embodiment 1, with only the control parameters and collaborative logic optimized based on the machine tool's machining characteristics. The specific working process is as follows: In electric drive mode, corresponding to no-load rapid positioning or light-load high-speed feed, the main solenoid directional valve 10 is connected to the right port to connect the oil ports of the front and rear covers of the cylinder assembly 8. The hydraulic control part stops, the electric part motor 1 starts and drives the piston rod assembly 9 to move through the transmission mechanism, the encoder assembly 5 controls the closed-loop accuracy, the second solenoid two-position directional valve 19 and the second oil tank 20 replenish and drain oil, and the air filter compensates for changes in gas volume to ensure smooth and vibration-free movement. In the hybrid drive mode, corresponding to the heavy-duty high-precision cutting conditions of the CNC machine tool, the main solenoid directional valve 10 is connected to the left port, and the electric and hydraulic control parts work together to strictly meet v1≤v2; v1 is determined by the fixed speed of the hydraulic control part motor 17 and the limited opening of the main solenoid directional valve 10 to ensure stable load-bearing capacity during the cutting process; v2 is adjusted by the CNC system to adjust the frequency of the electric part motor 1 to dynamically match the cutting speed requirements, and is always greater than v1 to avoid overload of the lead screw drive pair; The hydraulic control unit provides the heavy load capacity required for cutting, the electric unit precisely controls the feed rate, the encoder assembly 5 provides real-time feedback of position information to compensate for minor deviations caused by cutting vibration, the accumulator 13 continuously replenishes oil, and the overflow valve 11 and the balance valve 18 prevent oil pressure fluctuations from affecting machining accuracy.

[0032] In hydraulic drive mode, corresponding to heavy-load retraction, the main solenoid directional valve 10 remains on the left side. The electric part only provides basic gear rotation power and does not bear the load. The purpose is to drive the lead screw transmission assembly 6 to rotate slightly, ensuring that the piston rod assembly 9 can retract smoothly. This avoids jamming between the lead screw and the piston rod assembly 9 after long-term heavy-load cutting, thus protecting the transmission components. The hydraulic motor 17 reverses, driving the bidirectional hydraulic pump 16 to output high-pressure oil, opening the right side of the bidirectional hydraulic lock 15, and pushing the piston rod assembly 9 to retract smoothly. The return oil replenishes the accumulator 13, and the remainder returns to the first oil tank 12, realizing the recycling of oil. The balance valve 18 limits the retraction speed of the piston rod assembly 9 to avoid impact caused by the weight of the workpiece, preventing damage to the CNC machine tool's cutting tools and workpieces, while protecting the hydraulic components and transmission components of the system.

[0033] In this embodiment, the adaptive switching of three drive modes balances the efficiency and accuracy requirements of CNC machine tool processing, while fully demonstrating the technical advantages of the present invention: the flexible switching of the three drive modes adapts to the multi-condition requirements of CNC machine tools, the high-precision control of the electric part ensures the machining accuracy, the large load-bearing capacity of the hydraulic part meets the requirements of heavy-duty cutting, the compact design of the system facilitates integration with other components of the CNC machine tool, and the coordinated work of various hydraulic components and transmission components improves the reliability and stability of the system, effectively solving the problems of insufficient load-bearing capacity or insufficient positioning accuracy of existing CNC machine tool feed actuators.

[0034] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A novel electro-hydraulic hybrid drive system, characterized in that, It includes an electric component, a hydraulic control component, a cylinder assembly (8), and a piston rod assembly (9). The electric component includes an electric motor (1), a reducer (2), a gearbox assembly (3), a gear transmission pair (4), an encoder assembly (5), a lead screw transmission pair assembly (6), and a piston locking nut (7). The hydraulic control section includes a main solenoid directional valve (10), an overflow valve (11), a first oil tank (12), an accumulator (13), a first solenoid two-position directional valve (14), a two-way hydraulic lock (15), a two-way hydraulic pump (16), a hydraulic control section motor (17), a balance valve (18), a second solenoid two-position directional valve (19), a second oil tank (20), and a shut-off valve; The piston locking nut (7) is fixed to the piston rod assembly (9) near the piston end through a radial hole. The piston rod assembly (9) has a cylindrical hollow section in the middle that is adapted to the lead screw drive assembly (6). The cylinder assembly (8) has an oil inlet and an oil outlet at both ends.

2. The novel electro-hydraulic hybrid drive system according to claim 1, characterized in that: The main electromagnetic reversing valve (10) switches between three working modes—electric drive, hydraulic drive, and hybrid drive—by switching its working position and coordinating the start and stop states of the electric motor (1) and the hydraulic motor (17). The encoder assembly (5) is connected to the lead screw drive assembly (6) for transmission, and the balance valve (18) is connected in series in the oil circuit between the main solenoid directional valve (10) and the cylinder assembly (8).

3. The novel electro-hydraulic hybrid drive system according to claim 2, characterized in that: In the electric drive mode, the main solenoid directional valve (10) switches to the right position, so that the front and rear cover oil ports of the cylinder assembly (8) are connected and the oil in the rod chamber and the rodless chamber are interconnected. When the hydraulic control motor (17) is powered off and stops, the power output of the electric motor (1) is transmitted sequentially through the reducer (2), gear transmission pair (4), and lead screw transmission pair assembly (6) to the piston rod assembly (9), driving its extension and retraction; The second electromagnetic two-position directional valve (19) works in conjunction with the second oil tank (20) to complete the replenishment and discharge of oil in the oil circuit, and the encoder assembly (5) detects the position of the piston rod assembly (9) in real time.

4. The novel electro-hydraulic hybrid drive system according to claim 2, characterized in that: In the hydraulic drive mode, the main solenoid directional valve (10) switches to the left position, the electric motor (1) starts and only provides the basic force for the rotation of the gear transmission pair (4), without bearing the load; The motor (17) of the hydraulic control section starts and drives the bidirectional hydraulic pump (16) to operate. The high-pressure oil generated enters the corresponding chamber of the cylinder assembly (8) through the bidirectional hydraulic lock (15) and the balance valve (18), pushing the piston rod assembly (9) to extend and retract. The accumulator (13) replenishes oil to the oil circuit through the shut-off valve, and the excess oil flows back to the first oil tank (12) through the overflow valve (11). The first electromagnetic two-position reversing valve (14) controls the oil replenishment action of the accumulator (13).

5. The novel electro-hydraulic hybrid drive system according to claim 2, characterized in that: In the hybrid drive mode, the electric part and the hydraulic part operate in coordination. The speed v1 of the hydraulic drive driving the piston rod assembly (9) alone and the speed v2 of the electric drive driving the piston rod assembly (9) alone satisfy v1≤v2. The speed and direction of the piston rod assembly (9) are controlled by the electric part, and the load capacity of the system is provided by the hydraulic part.

6. The novel electro-hydraulic hybrid drive system according to claim 1, characterized in that: The cylinder assembly (8) is provided with an air filter, which is used to compensate for the gas volume difference between the rod chamber and the rodless chamber of the cylinder assembly (8) when the piston rod assembly (9) extends and retracts.

7. The novel electro-hydraulic hybrid drive system according to claim 3, characterized in that: The oil inlet of the second electromagnetic two-position directional valve (19) is connected to the second oil tank (20), and the oil outlet is connected to the connecting oil circuit between the rod chamber and the rodless chamber of the cylinder assembly (8) for oil replenishment and discharge in electric drive mode.

8. The novel electro-hydraulic hybrid drive system according to claim 4, characterized in that: The accumulator (13) is connected to the oil inlet side of the two-way hydraulic lock (15) through a shut-off valve, and the first electromagnetic two-position directional valve (14) is connected in parallel to the inlet of the accumulator (13).

9. The novel electro-hydraulic hybrid drive system according to claim 1, characterized in that: The lead screw drive assembly (6) includes a lead screw, a rotary seal assembly, a bushing, a key, a gear lock nut, and an encoder connecting shaft; The right end of the lead screw is fixed to the driven gear of the gear transmission pair (4), and the protruding part of the lead screw shaft is connected to the shaft hole of the encoder assembly (5).

10. The novel electro-hydraulic hybrid drive system according to claim 1, characterized in that: The output end of the electric motor (1) is fixedly connected to the input end of the reducer (2) and constitutes a power transmission unit. The output end of the reducer (2) is fixedly connected to the drive gear of the gear transmission pair (4).

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