Hydraulic valve linear driving pilot module and control method

Abstract

The hydraulic valve linear driving pilot module comprises a stepping motor, a two-stage reduction gear and a main control circuit board, the hydraulic valve linear driving pilot module capable of directly driving a valve element to move is formed, high-precision closed-loop control over the valve element can be achieved due to the fact that the hydraulic valve linear driving pilot module does not have the hysteresis characteristic, and due to the fact that a pilot oil way is not needed, the hydraulic valve linear driving pilot module can be used for directly driving the valve element to move. And the anti-pollution capability is greatly enhanced. According to the hydraulic valve linear driving pilot module and the control method, the hydraulic valve linear driving pilot module can replace a traditional hydraulic control pilot module, and digital and intelligent development of engineering machinery and agricultural machinery is facilitated.

Description

Technical Field

[0001] The invention relates to a hydraulic valve linear drive pilot module and a control method, belonging to the technical field of agricultural machinery / engineering machinery. Background Art

[0002] In the field of agricultural machinery / construction machinery, the hydraulic system is the main power system, and the hydraulic valve is the key core component in the hydraulic system, controlling the flow and direction of the oil. Its stability and reliability directly affect the stability and control performance of the host product.

[0003] With the development of electronic information technology, key components such as hydraulic valves are developing towards intelligence and digitalization. At present, most common electric proportional valves and digital valves on the market use proportional pressure reducing valves or proportional throttle valves as pilot valves. By changing the pressure of the pilot chambers on both sides of the main valve, the main valve core is driven to move. Hall or LVDT (Linear Variable Displacement Transducer) displacement sensors are used to collect valve core displacement signals in real time, thereby achieving precise control of valve core displacement and flow. However, this type of solution still has a disadvantage: it has high requirements for the cleanliness of the oil. When impurities are mixed into the oil, it will cause the pilot oil circuit to be blocked, which will cause problems such as valve jamming and no operation. Equipment such as agricultural machinery will have the problem of sharing the transmission oil tank with the hydraulic oil tank, which makes it difficult to ensure the cleanliness of the oil, which can easily cause the pilot oil circuit to be blocked and the hydraulic lifting system to be unreliable. In actual use, the cleanliness of the oil needs to be tested regularly. If the oil is not changed regularly, the cost of use will increase, which will seriously affect the working efficiency of agricultural machinery.

[0004] Therefore, the hydraulic valve linear drive pilot module launched can effectively solve the problem of sensitivity to oil cleanliness, improve the stability of the hydraulic system, and ensure the reliability and excellent controllability of the host product.

[0005] At present, the linear drive pilot modules launched on the market have the following disadvantages:

[0006] (1) The process thrust meets the requirements, but the holding force is insufficient:

[0007] In order to ensure that the valve core can automatically reset to the zero position after the power is lost to the drive module, the mainstream linear drive pilot module transmission structures on the market currently do not have self-locking capabilities. The valve core is in a stationary state when a fixed displacement is maintained. At this time, the motor is in a blocked state. In order to keep the valve core position unchanged, a certain current needs to be applied to the stepper motor coil to lock the shaft. However, in order to reduce the heat generated by the motor so that its life will not be greatly shortened, a semi-flow control mode is often used, which will cause the holding torque of the stepper motor to be halved, resulting in a smaller holding force.

[0008] (2) Open-loop control leads to insufficient valve core control accuracy:

[0009] There is no integrated angle encoder or displacement sensor inside EMA to feedback the valve core displacement signal. It adopts stepper motor open-loop control to realize the control of valve core displacement. However, there are problems such as poor positioning accuracy, poor load resistance, and step loss in the stepper open-loop control process, which makes the valve core displacement control inaccurate.

[0010] (3) Slow response speed:

[0011] Since the torque of the stepper motor itself is relatively small, a larger reduction ratio is required to decelerate the motor in order to output the required thrust. However, as the reduction ratio increases, the response speed of the valve core displacement will decrease. Summary of the invention

[0012] Purpose: In order to overcome the deficiencies in the prior art, the present invention provides a hydraulic valve linear drive pilot module and a control method.

[0013] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is:

[0014] In a first aspect, a hydraulic valve linear drive pilot module includes: a housing, a stepper motor, a gear bracket, a primary reduction gear, a secondary reduction gear, a rack, a magnetic encoder, and a main control circuit board.

[0015] A stepper motor and a gear bracket are arranged in the shell. The primary reduction gear and the secondary reduction gear are respectively installed on the gear bracket after being interference fit with the gear shaft. The motor shaft of the stepper motor is interference fit with the motor gear and meshes with the large gear of the primary reduction gear. The small gear of the primary reduction gear meshes with the large gear of the secondary reduction gear. The small gear of the secondary reduction gear meshes with the rack. The front end of the rack is used to connect the valve core of the valve body. A magnet is arranged on the shaft side of the secondary reduction gear. A magnetic encoder is arranged on the gear bracket outside the magnet. The magnetic encoder feeds back the angle signal of the rotation of the secondary reduction gear to the main control circuit board.

[0016] The housing is provided with a connector, the port of which is connected to the main control circuit board. The connector is used for bridging a plurality of linear drive pilot modules to form a CAN network.

[0017] The main control circuit board is used to control the stepper motor.

[0018] As a preferred solution, the housing includes: a driving module bottom shell and a driving module upper cover.

[0019] As a preferred solution, the magnetic encoder adopts a Hall encoder. The measuring chip of the Hall encoder detects the angle of rotation of the gear shaft by sensing the magnetic steel installed on the secondary reduction gear shaft, and transmits the angle signal to the main control circuit board in the form of PWM.

[0020] As a preferred solution, a fault indicator light is provided on the housing.

[0021] As a preferred solution, a sealing ring groove is provided on the driving module bottom shell or the driving module upper cover, and a sealing ring is installed on the sealing ring groove.

[0022] In a second aspect, a control method for a hydraulic valve linear drive pilot module specifically includes:

[0023] After power-on, the linear drive pilot module performs a self-check. When the self-check is normal, it proceeds to the next step.

[0024] The real-time main valve body oil temperature is obtained. When the main valve body oil temperature is within the first threshold range, the linear drive pilot module enters the normal working mode, controls the stepper motor to rotate according to the target displacement instruction of the valve core, and pushes the valve core to reach the target displacement at the first speed.

[0025] The real-time main valve body oil temperature is obtained. When the main valve body oil temperature is within the second threshold range, the linear drive pilot module enters the low-speed mode, controls the stepper motor to rotate according to the target displacement instruction of the valve core, and pushes the valve core to move at the second speed to achieve the target displacement.

[0026] The real-time main valve body oil temperature is obtained. When the main valve body oil temperature is within the third threshold range, the linear drive pilot module enters the ultra-low speed mode, controls the stepper motor to rotate according to the target displacement instruction of the valve core, and pushes the valve core to move at the third speed to achieve the target displacement.

[0027] When the valve core reaches the target position, it enters the holding mode, the stepper motor locks the shaft, and the control current is halved.

[0028] As a preferred solution, it also includes: when an abnormality occurs in the self-check, a warning code is issued, and the linear drive pilot module clears the fault and works after the self-check is normal.

[0029] As a preferred solution, it also includes: when the valve core is stuck, issuing an instruction to enter a dither mode, wherein the dither mode means that the linear drive pilot module uses an extremely low speed mode to push the valve core to reciprocate until the valve core is no longer stuck.

[0030] As a preferred solution, the method for controlling the rotation of the stepper motor according to the target displacement instruction of the valve core specifically includes:

[0031] Compare the target spool displacement signal with the actual spool displacement obtained by feedback conversion of the magnetic encoder to obtain the spool displacement deviation signal.

[0032] Pass the spool displacement deviation signal through the position loop PID to calculate the target speed of the stepper motor.

[0033] Compare the target speed of the stepper motor with the actual motor speed obtained by feedback of the magnetic encoder to obtain the speed deviation signal.

[0034] Pass the speed deviation signal through the speed loop PID to calculate the target current value.

[0035] The target current value is loaded onto the corresponding current of the coil through the current closed-loop function of the stepper motor drive circuit, driving the stepper motor to rotate by a corresponding angle.

[0036] As a preferred solution, the first threshold range is set to 5°C < Temp <= 50°C, the second threshold range is set to (-15°C < Temp <= 5°C) || (Temp > 50°C), and the third threshold range is set to Temp < -15°C. Here, Temp represents the real-time oil temperature of the main valve body, and || represents the OR logic.

[0037] Beneficial effects: A hydraulic valve linear drive pilot module and control method provided by the present invention include a stepper motor, a two-stage reduction gear, and a main control circuit board, constituting a hydraulic valve linear drive pilot module that can directly drive the spool movement. Due to its own lack of hysteresis characteristics, it can achieve high-precision closed-loop control of the spool, and due to the absence of a pilot oil circuit, its anti-pollution ability is greatly enhanced. This hydraulic valve linear drive pilot module can replace the traditional hydraulic control pilot module, which is beneficial to the development of construction machinery and agricultural machinery towards the direction of digitalization and intelligentization.

[0038] Compared with the prior art, its advantages are as follows:

[0039] (1) The present invention internally integrates a high-torque stepper motor, a two-stage reduction gear, a high-precision magnetic encoder, and a main control circuit board. The drive module has a compact structure, can automatically switch the working mode according to the external environment, and combines the three-level closed-loop control programs of the position loop, speed loop, and current loop, which can accurately achieve the closed-loop control of the spool displacement. By selecting an appropriate reduction ratio while balancing the holding force and response speed, it can meet the requirements of agricultural machinery equipment and cranes of different tonnages.

[0040] (2) The present invention can be used as an independent drive module in cooperation with the controlled valve, with high flexibility.

[0041] (3) Multiple devices of the present invention can be cascaded through jumper wires, reducing the use of wiring harnesses. While reducing the wiring harness cost, it is also convenient for maintenance and can be widely applied to multi-way valves.

[0042] (4) The present invention does not require pilot oil, does not have problems such as pilot line blockage, and does not require high oil cleanliness. It can be widely used in agricultural machinery equipment that uses a transmission oil tank and a hydraulic oil tank.

[0043] (5) The present invention can select a corresponding working mode according to the oil temperature and can be applied to cranes that are sensitive to temperature.

[0044] (6) The present invention adopts a three-stage closed-loop valve core displacement control method, which can achieve accurate valve core displacement closed-loop control while ensuring the response speed.

[0045] (7) The present invention adopts a high-precision magnetic encoder to collect the angle of rotation of the reduction gear shaft, which is used to detect the angle and speed of rotation, and then obtain the real-time displacement signal of the valve core. The three-level closed-loop control of position loop, speed loop and current loop is adopted to realize high-precision closed-loop control of valve core displacement. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the overall structure of the hydraulic valve linear drive pilot module.

[0047] Figure 2 Schematic diagram of the internal structure of the bottom shell.

[0048] Figure 3 Schematic diagram of the internal structure of the upper cover.

[0049] Figure 4 It is a schematic diagram of the two-stage reduction gear structure.

[0050] Figure 5 It is a flow chart of the control method of the present invention.

[0051] Figure 6 It is a schematic diagram of the valve core displacement closed-loop control process.

[0052] Among them: 1-drive module cover, 2-fault indicator light, 3-connector, 4-drive module bottom shell, 5-high-precision magnetic encoder, 6-magnetic steel, 7-gear bracket, 8-rack clamping bearing, 9-first-stage reduction gear, 10-limiting nylon sheet, 11-sealing ring groove, 12-stepping motor. 13-motor front cover, 14-motor gear, 15-second-stage reduction gear, 16-sealing ring, 17-rack, 18-main control circuit board. DETAILED DESCRIPTION

[0053] The following is a clear and complete description of the technical solutions in the examples of the present invention in conjunction with the accompanying drawings in the examples of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the protection scope of the present invention.

[0054] The present invention will be further described below in conjunction with specific embodiments.

[0055] Example 1

[0056] This embodiment introduces a hydraulic valve linear drive pilot module, such as Figure 1 As shown, it includes: a housing, a stepper motor 12, a gear bracket 7, a primary reduction gear 9, a secondary reduction gear 15, a rack 17, a high-precision magnetic encoder 5, and a main control circuit board 18.

[0057] like Figure 2 , Figure 3 As shown, a stepper motor 12 and a gear bracket 7 are arranged in the housing, and the first-stage reduction gear 9 and the second-stage reduction gear 15 are respectively installed on the gear bracket 7 after being interference-fitted with the gear shaft. Figure 4 As shown, the motor shaft of the stepper motor 12 is interference fitted with the motor gear 14, and meshes with the large gear of the primary reduction gear 9, the small gear of the primary reduction gear 9 meshes with the large gear of the secondary reduction gear 15, the small gear of the secondary reduction gear 15 meshes with the rack 17, and then drives the rack to move linearly, and the front end of the rack is used to connect the valve core of the valve body; the shaft side of the secondary reduction gear 15 is provided with a magnet 6, and the gear bracket 7 outside the magnet 6 is provided with a high-precision magnetic encoder 5, and the high-precision magnetic encoder 5 feeds back the angle signal of the rotation of the secondary reduction gear 15 to the main control circuit board 18.

[0058] The housing is provided with a connector 3, and a port of the connector 3 is connected to the main control circuit board 18. When a multi-way valve is installed with a multi-hydraulic valve linear drive pilot module, a CAN network can be formed by jumper wires through the connector 3 to reduce the use of wiring harnesses.

[0059] The main control circuit board 18 is used to control the stepper motor 12 .

[0060] Furthermore, a motor front end cover 13 is provided at the front end of the stepper motor 12 .

[0061] Furthermore, the stepper motor 12 adopts a two-phase hybrid stepper motor with a step angle of 1.8°, and is fastened to the gear bracket 7 using a four-point fixing method. When the stepper motor 12 rotates clockwise, the front end of the rack 17 drives the valve core to extend, and when it rotates counterclockwise, the rack 17 drives the valve core to retract.

[0062] Furthermore, the housing includes: a driving module bottom shell 4 and a driving module upper cover 1 .

[0063] Furthermore, a ball bearing is embedded in the gear bracket to reduce the friction between the gear shaft and the bracket.

[0064] Furthermore, the high-precision magnetic encoder 5 adopts a Hall encoder, and the measurement chip of the Hall encoder detects the angle of rotation of the gear shaft by sensing the magnetic steel installed on the secondary reduction gear shaft, and transmits the angle signal to the main control circuit board in the form of PWM.

[0065] Furthermore, the magnet 6 is installed in a shaft sleeve and is installed on the secondary reduction gear shaft through the shaft sleeve. Due to the backlash when the gears are engaged, the magnet installed on the secondary reduction gear shaft can more accurately reflect the actual displacement of the valve core than when it is installed on the motor shaft, thereby achieving more accurate closed-loop control of the valve core displacement, and thus the main engine has more superior operating performance.

[0066] Furthermore, the shell is provided with a plurality of screw holes for connecting with the valve body. Preferably, four screws are used to fasten the bottom of the shell of the hydraulic valve linear drive pilot module to the valve body, which can effectively avoid the valve core movement from getting stuck due to the change of force direction caused by misalignment during the installation process.

[0067] Furthermore, a fault indicator light 2 is provided on the shell, and the fault type can be judged according to the color and flashing frequency of the indicator light. When a fault occurs, the user can have a general understanding of the fault category without professional equipment to read the fault code, and can feedback the fault to professional after-sales personnel so that the professionals can give timely response plans to eliminate and restore the fault, which greatly reduces the after-sales maintenance cost.

[0068] Furthermore, a rack pressing bearing 8 is provided at one end of the rack 17 .

[0069] Furthermore, the gear bracket 7 is integrally formed by an aluminum die-casting process and is mounted on the driving module bottom shell 4 by fastening screws.

[0070] Furthermore, a limited position nylon sheet 10 is provided on the gear shaft of the primary reduction gear 9 .

[0071] Further, a sealing ring groove 11 is provided on the bottom case or the upper cover of the drive module. A sealing ring is installed on the sealing ring groove 11. The linear drive pilot module of the hydraulic valve is applied to agricultural machinery and cranes, and the working environment is relatively harsh. There are not only electromagnetic interference and mechanical vibration, but also direct sunlight, and it is directly exposed to the outside in rainy days. Therefore, good waterproof and dustproof performance is required. The present invention reserves a sealing ring groove on the housing, and after installing a high-strength waterproof and dustproof sealing ring, it is pressed tightly by the upper cover to achieve the protection effect of IP67 level.

[0072] Further, the main control circuit board 18 includes: a power module, an MCU minimum system, a stepping motor drive circuit, a CAN bus transceiver module, an anti-interference module, an over-voltage and under-voltage protection module, and a temperature sensing module. It performs data interaction with the outside through the CAN bus transceiver module, collects the angle signal fed back by the high-precision magnetic encoder and converts it into a spool displacement signal. After being processed by the closed-loop control program, it drives the stepping motor drive circuit to work, so that the stepping motor rotates by the required angle.

[0073] Embodiment 2:

[0074] This embodiment introduces a control method for the linear drive pilot module of a hydraulic valve, as Figure 5 shown, specifically including:

[0075] After power-on, the linear drive pilot module performs self-check. When the self-check is normal, it enters the next step.

[0076] When the temperature sensor detects that the oil temperature of the main valve body ranges from 5°C < Temp <= 50°C, the linear drive pilot module enters the normal working mode, controls the rotation of the stepping motor according to the target displacement command of the spool, and pushes the spool to the target displacement at a speed of 100 mm / s.

[0077] When it is detected that the oil temperature of the main valve body ranges from (-15°C < Temp <= 5°C) || (Temp > 50°C), the linear drive pilot module enters the low-speed mode, controls the rotation of the stepping motor according to the target displacement command of the spool, and pushes the spool to move to the target displacement at a speed of 60 mm / s. On the one hand, the speed is reduced to increase the output force to overcome the oil resistance in the low-temperature case, and on the other hand, the heat generation of the motor in the high-temperature case is reduced.

[0078] When it is detected that the oil temperature of the main valve body is lower than -15°C, the linear drive pilot module enters the extremely low-speed mode, controls the rotation of the stepping motor according to the target displacement command of the spool, and pushes the spool to move to the target displacement at a speed of 10 mm / s.

[0079] When the spool displacement reaches the target position, it enters the holding mode, the stepping motor locks the shaft, and the control current is halved.

[0080] Among them, || represents the OR logic.

[0081] Furthermore, it also includes: when an abnormality occurs in the self-check, a warning code is issued, and the linear drive pilot module clears the fault and works after the self-check is normal.

[0082] Furthermore, it also includes: when the valve core is stuck, an instruction to enter the dither mode is issued, and the dither mode means that the linear drive pilot module adopts an extremely low speed mode to push the valve core to reciprocate until the valve core is no longer stuck.

[0083] Furthermore, it also includes: obtaining the oil temperature of the main valve body in real time, and switching to a corresponding working mode when the oil temperature of the main valve body changes to another threshold range.

[0084] Further, such as Figure 6 As shown, the method for controlling the rotation of the stepper motor according to the target displacement instruction of the valve core specifically includes:

[0085] The host controller sends the target valve core displacement signal through the CAN bus, compares it with the actual valve core displacement obtained by the magnetic encoder feedback conversion, and obtains the valve core displacement deviation signal.

[0086] The valve core displacement deviation signal is calculated through the position loop PID to obtain the target speed of the stepper motor.

[0087] The target speed of the stepper motor is compared with the actual motor speed obtained through feedback from the magnetic encoder to obtain a speed deviation signal.

[0088] The speed deviation signal is calculated through the speed loop PID to obtain the target current value.

[0089] The target current value is loaded onto the corresponding current on the coil through the current closed-loop function of the stepper motor drive circuit itself, driving the stepper motor to rotate the corresponding angle, thereby completing the displacement closed-loop control of the valve core.

[0090] The working principle of the hydraulic valve linear drive pilot module of the present invention is as follows: after power-on, it will first perform a self-check, and enter the normal working mode when there is no fault in the self-check. At the same time, the temperature sensing module of the drive module will measure the oil temperature of the main valve body connected to it, and select different working speeds and output forces to work according to the measured temperature. When the hydraulic valve linear drive pilot module receives the command displacement signal on the CAN bus, it first compares it with the actual valve core displacement converted from the feedback angle signal of the high-precision magnetic encoder to obtain a deviation signal, and then calculates the control signal of the stepper motor through the closed-loop control algorithm, and applies it to the stepper motor drive circuit to make the motor rotate through the required angle, thereby completing the closed-loop control of the valve core displacement.

[0091] Embodiment 3:

[0092] This paper introduces the working principle of a hydraulic valve linear drive pilot module and control method, including a high-torque stepper motor, a two-stage reduction gear, a rack, a high-precision magnetic encoder, and a main control circuit board. It supports CAN bus communication and has a compact mechanical structure. It has a smaller size while ensuring large thrust. It uses a stepper motor as a power element. After two-stage gear reduction, it drives the rack to move, and then drives the main valve core to move. The magnetic encoder measures the rotation angle of the secondary reduction gear shaft to achieve accurate valve core displacement closed-loop control. The control method of the hydraulic valve linear drive pilot module can effectively avoid the influence of the hysteresis characteristics of the solenoid valve itself on the valve core control characteristics, and improve the response speed of the system and the control accuracy of the flow; at the same time, since there is no need for pilot oil, there is no fear of causing problems such as clogging of the pilot oil circuit and causing the valve core to get stuck, and the requirements for the cleanliness of the oil are greatly reduced. It can be widely used in agricultural machinery and other equipment that uses a transmission oil tank and a hydraulic oil tank. In addition, the hydraulic valve linear drive pilot module has a fault diagnosis function, which can identify faults such as valve core sticking, sensor failure, system overpressure, underpressure, CAN-BUS fault, and valve core not being in the middle position. The drive circuit has a current closed-loop function, which can monitor the current in real time and adjust the output force according to demand. The built-in temperature sensor monitors the external temperature in real time and can automatically adjust the working mode according to the external temperature. It can be used in temperature-sensitive engineering machinery such as cranes.

[0093] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A hydraulic valve linear drive pilot module, The invention comprises, wherein: include: Housing, stepper motor, gear bracket, primary reduction gear, secondary reduction gear, rack, magnetic encoder, main control circuit board; A stepper motor and a gear bracket are arranged in the shell, the primary reduction gear and the secondary reduction gear are respectively installed on the gear bracket after being interference fitted with the gear shaft, the motor shaft of the stepper motor is interference fitted with the motor gear, and meshes with the large gear of the primary reduction gear, the small gear of the primary reduction gear is meshed with the large gear of the secondary reduction gear, the small gear of the secondary reduction gear is meshed with the rack, and the front end of the rack is used to connect the valve core of the valve body; a magnet is arranged on the shaft side of the secondary reduction gear, and a magnetic encoder is arranged on the gear bracket outside the magnet, and the magnetic encoder feeds back the angle signal of the rotation of the secondary reduction gear to the main control circuit board; The housing is provided with a connector, the port of which is connected to the main control circuit board; the connector is used for bridging multiple linear drive pilot modules to form a CAN network; The main control circuit board is used to control the stepper motor.

2. A hydraulic valve linear drive pilot module according to claim 1, characterized in that: The housing comprises: a driving module bottom shell and a driving module upper cover.

3. A hydraulic valve linear drive pilot module according to claim 1, characterized in that: The magnetic encoder adopts a Hall encoder. The measuring chip of the Hall encoder detects the angle of rotation of the gear shaft by sensing the magnetic steel installed on the secondary reduction gear shaft, and transmits the angle signal to the main control circuit board in the form of PWM.

4. A hydraulic valve linear drive pilot module according to claim 1, characterized in that: A fault indicator light is arranged on the housing.

5. The hydraulic valve linear drive pilot module according to claim 2, characterized in that: The driving module bottom shell or the driving module upper cover is provided with a sealing ring groove, and a sealing ring is installed on the sealing ring groove.

6. A control method for a hydraulic valve linear drive pilot module according to any one of claims 1 to 5, characterized in that: Specifically include: After power-on, the linear drive pilot module performs a self-check. If the self-check is normal, it proceeds to the next step; The real-time oil temperature of the main valve body is obtained. When the oil temperature of the main valve body is within the first threshold range, the linear drive pilot module enters the normal working mode, controls the stepper motor to rotate according to the target displacement instruction of the valve core, and pushes the valve core to reach the target displacement at the first speed; The real-time oil temperature of the main valve body is obtained. When the oil temperature of the main valve body is within the second threshold range, the linear drive pilot module enters the low-speed mode, controls the stepper motor to rotate according to the target displacement instruction of the valve core, and drives the valve core to move at the second speed to reach the target displacement; The real-time oil temperature of the main valve body is obtained. When the oil temperature of the main valve body is within the third threshold range, the linear drive pilot module enters the extremely low speed mode, controls the stepper motor to rotate according to the target displacement instruction of the valve core, and drives the valve core to move at the third speed to reach the target displacement; When the valve core reaches the target position, it enters the holding mode, the stepper motor locks the shaft, and the control current is halved.

7. The control method according to claim 6, characterized in that: Also includes: When an abnormality occurs in the self-check, a warning code is issued, and the linear drive pilot module works after the fault is cleared and the self-check is normal.

8. The control method according to claim 6, characterized in that: Also includes: When the valve core is stuck, an instruction to enter the dither mode is issued, and the dither mode means that the linear drive pilot module uses an extremely low speed mode to push the valve core to reciprocate until the valve core is no longer stuck.

9. The control method according to claim 6, characterized in that: The method for controlling the rotation of a stepper motor according to a target displacement instruction of a valve core specifically comprises: The target valve core displacement signal is compared with the actual valve core displacement obtained by the magnetic encoder feedback conversion to obtain the valve core displacement deviation signal; The spool displacement deviation signal is passed through the position loop PID to calculate the target speed of the stepper motor; The target speed of the stepper motor is compared with the actual motor speed obtained by the feedback of the magnetic encoder to obtain the speed deviation signal; The speed deviation signal is passed through the speed loop PID to calculate the target current value; The target current value is loaded onto the corresponding current of the coil through the current closed-loop function of the stepper motor drive circuit itself, and the stepper motor is driven to rotate by a corresponding angle.

10. The control method according to claim 6, characterized in that: The first threshold range is set to 5°C < Temp <= 50°C, the second threshold range is set to (-15°C < Temp <= 5°C) || (Temp > 50°C), and the third threshold range is set to Temp < -15°C. Here, Temp represents the real-time main valve body oil temperature, and || represents the OR logic.

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