Hydraulic control system for a walking unit of a coal mining machine and method of operation thereof

Abstract

The application provides a hydraulic control system for a walking part of a coal mining machine and a working method thereof, and comprises a coal mining machine frame, a walking part, a pin rail, a walking wheel, a double-acting hydraulic cylinder, a traction motor, a fuzzy PID controller, a speed sensor and a current sensor. The double-acting hydraulic cylinder is installed between the coal mining machine frame and the walking part, and the walking part is driven to slightly swing through the extension and retraction movement of the hydraulic cylinder, so that the walking wheel and the pin rail are quickly and synchronously engaged when the coal mining machine starts. The controller receives the feedback signals of the speed sensor and the current sensor in real time, dynamically adjusts the movement of the hydraulic cylinder according to the engagement state of the walking part, so as to ensure the synchronous engagement of the walking wheel and the pin rail. The controller also integrates a locking loop, uses a hydraulic control check valve to realize the accurate locking of the piston at the engagement position, prevents the relative sliding after engagement, adjusts the output of the hydraulic cylinder through fuzzy PID control, intelligently adjusts the speed and position of the walking wheel, and realizes the automatic correction of the engagement problem.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal mining machine control, in particular to a hydraulic control system for the walking part of a coal mining machine and a working method thereof. BACKGROUND

[0002] The existing control system for the walking part of a coal mining machine has many limitations in the meshing of the walking wheel and the pin rail, and usually relies on mechanical driving and simple hydraulic adjustment. This method has poor adaptability to complex working conditions, which leads to problems such as asynchronous meshing and insecure meshing of the system in a high-load environment.

[0003] Specifically, when the walking wheel and the pin rail cannot mesh synchronously, relative sliding of the walking part is likely to occur, which intensifies the wear of the walking system of the coal mining machine and reduces the service life and reliability of the equipment.

[0004] In order to avoid these problems, coal mining equipment manufacturers and research institutions have been committed to developing more intelligent hydraulic control systems to ensure that the walking part of the coal mining machine and the pin rail can achieve stable and synchronous rapid meshing under various working conditions. In the current research, the hydraulic control system has become an important direction in the field of control of the walking part of the coal mining machine due to its fast response, large thrust and high control precision. The combination of double-acting hydraulic cylinders and electro-hydraulic proportional control valves enables the hydraulic system to automatically adjust the position and swing angle of the walking part based on feedback signals, thereby achieving precise synchronization of the walking wheel and the pin rail. The key to this control system is to use sensors to monitor parameters such as pressure, speed and displacement in real time, and intelligently adjust the output of the hydraulic cylinder based on a closed-loop control mode to respond to dynamic load requirements in complex mines. However, the existing hydraulic control system still has deficiencies in locking and closed-loop control, especially in the design of preventing relative sliding after the walking wheel and the pin rail mesh, which causes loosening after meshing and increases the difficulty of system maintenance.

[0005] At the same time, with the increasing intelligence of coal mining machine equipment, adaptive control algorithms such as fuzzy PID have been gradually introduced into the hydraulic control system. Fuzzy PID control technology has strong robustness and adaptability, and through real-time adjustment of controller parameters, it can effectively respond to parameter fluctuations in mine environments, further improving the precision of walking part meshing. However, due to the complexity of the mine operating environment and the variability of the working conditions, the traditional PID control system still has problems of response delay and insufficient adjustment when facing load mutations and parameter changes. Some research has shown that with the assistance of multiple sensor feedback, more accurate synchronous control can be achieved by optimizing the fuzzy PID control algorithm, but this technology still needs a large number of experimental verification under complex working conditions.

[0006] Therefore, developing a comprehensive control solution that integrates hydraulic system, fuzzy PID control, locking loop and multi-sensor closed-loop feedback has become a technical trend in the current field of coal mining equipment control. Summary of the Invention

[0007] Each exemplary embodiment of the present application provides a hydraulic control system for a coal mining machine travel part and a working method thereof, so as to at least have the technical effect of improving the efficiency of rapid and accurate engagement between the coal mining machine travel wheel and the pin rail.

[0008] Each exemplary embodiment of the present application provides a hydraulic control system for the traveling part of a coal mining machine, comprising a coal mining machine frame, a hydraulic control unit, a pin rail, a traveling part, a traveling wheel, a double-acting hydraulic cylinder, a traction motor, a fuzzy PID controller, and a frequency converter; the double-acting hydraulic cylinder is arranged between the coal mining machine frame and the traveling part, the traveling part is hinged to the coal mining machine frame, the traction motor is connected to a current sensor, and a speed sensor is connected to the piston rod of the double-acting hydraulic cylinder; the hydraulic control unit is configured to use the double-acting hydraulic cylinder to apply a force to the traveling part when the coal mining machine starts working, and the traveling part is hinged It is connected to the coal mining machine frame and the guide shoe is not in direct contact with the pin rail. The walking part is subjected to force to generate a small angle swing, driving the walking wheel and the pin rail to achieve rapid engagement. The speed sensor detects the piston movement speed and sends a speed signal difference. The current sensor is configured to collect the current fluctuation signal difference of the traction motors on both sides. The current fluctuation signal difference and the speed signal difference are processed together and sent to the fuzzy inference PID controller; the fuzzy inference PID controller is configured to adjust the movement of the double-acting hydraulic cylinder to complete synchronous rapid engagement, and the frequency converter adjusts the speed of the traction motors on both sides until the two walking wheels are synchronized and quickly engaged.

[0009] Preferably, the hydraulic control unit includes a quick-engagement hydraulic control circuit and a synchronous-engagement hydraulic control circuit; wherein, the quick-engagement hydraulic control circuit includes an oil tank, a filter, a motor, a variable pump, an overflow valve, an electro-hydraulic servo valve, a one-way valve, a double-acting hydraulic cylinder, a speed sensor, a fuzzy PID controller, a command speed signal generator, and a comparator; the quick-engagement hydraulic control circuit is realized by a locking circuit composed of two hydraulically controlled one-way valves, and the hydraulically controlled one-way valve can realize the locking of the piston rod at any position in the cylinder, and the electro-hydraulic servo valve adopts a three-position four-way electro-hydraulic servo valve, and the middle position function adopts a Y-type. When it is in the middle position, the oil port is directly connected to the oil tank, and the left and right oil circuits of the cylinder are locked by the one-way valve in the locking circuit. The valve is sealed, the piston rod stops moving and is locked; when it is in the left position, the pressure oil enters the rodless chamber of the cylinder through the one-way valve, pushing the piston rod to the right, completing the meshing of the travel wheel and the pin rail. After the travel wheel and the pin rail are engaged, no relative movement occurs. The speed sensor detects the piston movement speed and sends a signal. The command speed signal generator sends a given speed signal. This signal and the speed signal detected by the speed sensor enter the comparator for calculation and then send the speed signal difference into the proportional amplifier. The proportional amplifier processes the speed signal difference and the current fluctuation signal difference into a unified signal. The unified signal is used as the input of the fuzzy PID controller. The fuzzy PID controller adjusts the working state of the electro-hydraulic servo valve to complete rapid engagement.

[0010] Preferably, the synchronous engagement hydraulic control circuit includes a walking wheel rapid engagement circuit, a traction motor, a current sensor, a frequency converter, a fuzzy PID controller, and a comparator; the current sensor monitors the current fluctuations of the two traction motors in real time to determine whether the walking wheels are successfully synchronously engaged with the pin rails. If the current fluctuations are too large or abnormal fluctuations occur, the system determines that the walking wheels on both sides are not synchronously engaged with the pin rails. At this time, the current sensors on both sides detect the current fluctuation signal difference. This current fluctuation signal difference and the speed signal difference are used as inputs to the fuzzy PID controller. The fuzzy PID controller outputs corresponding pressure oil by controlling the opening size and direction of the electro-hydraulic servo valve, driving the piston movement in the oil cylinder, and then driving the walking part to achieve synchronous rapid engagement.

[0011] Preferably, the various parts of the hydraulic control unit form a closed-loop control circuit, the speed sensor detects the piston movement speed and sends the speed signal to the comparator 1; the command speed signal generator sends a given signal, which is compared with the speed signal in the comparator 1 and then sent to the comparator 3; the current sensor detects the current fluctuation signal in the traction motor due to the lack of synchronous engagement and calculates the current fluctuation signal difference in the comparator 2, and the comparator 2 sends the current fluctuation signal difference to the comparator 3; the comparator 3 sends the input speed signal difference and the current fluctuation signal difference together to the proportional amplifier, and the proportional amplifier converts the input signal into a unified signal and sends it to the fuzzy PID controller after amplification. The unified signal is used as the controller input, and the fuzzy PID controller drives the piston movement in the oil cylinder by adjusting the working state of the electro-hydraulic servo valve and outputting hydraulic oil to act on the walking part. The walking part is subjected to force to generate a small swing, driving the walking wheel and the pin rail to achieve rapid engagement until the synchronous engagement of the walking parts on both sides is completed.

[0012] Preferably, the output of the speed sensor is input as a feedback signal into the comparator for comparison with the specified signal, and after processing by the controller, is sent to the amplifier to adjust the working state of the flow control valve and adjust the loop flow, pressure and direction; the output of the current sensor is sent as a feedback signal to the frequency converter to adjust the motor speed. When the walking parts on both sides are not synchronously engaged, the frequency converter adjusts the speed of the traction motors on both sides, increases the speed of the non-engaged motor, and reduces the speed of the engaged motor until synchronous and rapid engagement is completed.

[0013] As a preference, the fuzzy inference PID controller adopts fuzzy inference PID regulation. When the deviation is large, the error is eliminated as soon as possible; when the deviation is small, the domain is narrowed, the fuzzy control rules are relatively increased, and overshoot and oscillation are suppressed; fuzzy logic is used and the PID parameters Kp, Ki and Kd are adjusted in real time according to the fuzzy rules. The establishment of the fuzzy PID includes fuzzification, determination of fuzzy rules and defuzzification; the controller inputs a unified signal and then performs fuzzy inference according to the fuzzy inference rules, and finally defuzzifies it, outputs the PID control parameters, adjusts the working state of the electromagnetic reversing valve, and the transmitter receives the feedback signal to adjust the control parameters. The various parts constitute a closed-loop control circuit; wherein, K is defined e is the gain of the controller error, K ec is the error; the gain of the rate of change, de / dt is the derivative of the error with respect to time; K p ,K i ,K d By K e , K ec Two variables are controlled, and the fuzzy control part continuously updates the iterative K e , K ec These two variables, K p ,K i ,Kd are the differential coefficient, proportional coefficient and integral coefficient respectively.

[0014] As an advantage, the fuzzy inference PID adjustment includes: setting K e ,K ec ,K P ,K I ,K D is the corresponding variable e,e c ,K p ,K i ,K d The language variables are set to {NB, NM, NS, ZO, PS, PM, PB}, the domain is selected to be {-6, -5, -4, -5, -2, -1, 0, 1, 2, 3, 4, 5, 6}, and the PID controller parameters are

[0015] K P =K P0 +ΔK P

[0016] K i =K i0 +ΔK i

[0017] K d =K d0 +ΔK d

[0018] Among them, K P0 , K i0 , K d0 As the initial value, the membership function chooses the classic trigonometric function.

[0019] Preferably, the command speed signal generator is a ramp signal generator, which sends a slowly rising or falling step signal. The step signal is dynamically adjusted with the feedback of the speed sensor, so that the walking part gradually swings and gradually approaches the pin rail until the walking wheel contacts the pin rail softly.

[0020] Preferably, the speed sensor and the current sensor are non-contact type and do not directly contact the measured element.

[0021] According to another aspect of the present application, a working method is also disclosed, which is applied to the hydraulic control system of the above-mentioned coal mining machine travel part, comprising the following steps:

[0022] S1, start the hydraulic system and initialize, the variable pump starts, the hydraulic oil is transported from the oil tank to the hydraulic system, and the pressure is prepared to be provided; the hydraulic cylinder pressure value is set to meet the system's demand for the thrust of the walking wheel; if the pressure is lower than the set value, the pump flow is increased; if the pressure is higher than the set value, the relief valve is opened to release the excess pressure;

[0023] S2, receive the feedback signals of the speed and current sensors, and adjust the 4 / 3 electro-hydraulic servo valve through fuzzy PID control, control the movement direction and speed of the piston in the hydraulic cylinder, and fine-tune the swing angle of the walking part, so that the walking wheel gradually approaches the pin rail until meshing;

[0024] S3, judge whether it is meshed or not, if not, execute step S2, if yes, detect the current fluctuation to judge whether it is synchronously meshed or not; if yes, enter the closed-loop control mode, continuously monitor the feedback of the speed sensor and the current sensor, and ensure that the walking part remains stable meshing; if not, automatically adjust the frequency converter and the hydraulic cylinder to realize accurate fine-tuning until synchronous meshing.

[0025] The application has the following beneficial effects:

[0026] 1. The system drives the walking part to swing slightly by using a double-acting hydraulic cylinder, the walking wheel and the pin rail can quickly and synchronously mesh at the moment when the coal mining machine starts, significantly shortening the time delay in the traditional mechanical meshing. The fuzzy PID controller receives the feedback signals of the speed sensor and the current sensor in real time, dynamically adjusts the movement trajectory of the hydraulic cylinder, ensures that the walking wheel and the pin rail realize the optimal meshing position and speed, and greatly improves the meshing accuracy.

[0027] 2. The hydraulic system adopts a locking circuit composed of a hydraulic control check valve, after the meshing is completed, the piston rod can be stably locked at any position, and the meshing failure problem caused by relative sliding after meshing is eliminated. The design can maintain the stable operation of the walking part in a harsh mine environment, even in the case of high load or vibration impact, the system can still effectively avoid meshing loosening, and improve the operation reliability.

[0028] 3. The fuzzy PID controller dynamically adjusts the pressure and movement direction of the hydraulic cylinder based on the feedback signals, can automatically correct the asynchronous meshing problem, the control system combines multiple inputs such as speed sensors, current sensors, etc., realizes the whole-process closed-loop control from the start of the walking part to synchronous meshing, and the fuzzy PID controller adjusts the PID parameters in real time, has strong anti-disturbance ability to the load fluctuation and parameter change that may occur in the system, has strong robustness, and is especially suitable for dynamic working condition requirements in complex mine environments. BRIEF DESCRIPTION OF DRAWINGS

[0029] The drawings described herein are used to provide further understanding of the present application, and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0030] Figure 1 is the structure diagram of synchronous quick meshing of the walking part of the coal mining machine.

[0031] Figure 2 is the principle diagram of the hydraulic control circuit of the quick meshing of the walking part of the coal mining machine.

[0032] Figure 3 is the principle diagram of the hydraulic control circuit of the synchronous quick meshing of the walking part of the coal mining machine.

[0033] Figure 4 is the principle diagram of the hydraulic control part of the walking part of the coal mining machine.

[0034] Figure 5 is the principle diagram of the fuzzy PID controller of the synchronous quick meshing of the walking part of the coal mining machine.

[0035] Figure 6 is the structure diagram of the fuzzy PID controller of the walking part of the coal mining machine.

[0036] Figure 7 is the working flow chart of the synchronous quick meshing control system of the walking part of the coal mining machine.

[0037] Wherein, 1, the frame of the coal mining machine; 2, the walking wheel; 3, the walking part; 4, the double-acting hydraulic cylinder; 5, the pin rail; 6, the traction motor; 7, the fuzzy PID controller; 8, the speed sensor; 9, the current sensor; 10, the frequency converter; 21, the oil tank; 22, the filter; 23, the motor; 24, the variable pump; 25, the overflow valve; 26, the three-position four-way electro-hydraulic servo valve; 27, the check valve; 28, the oil cylinder; 29, the speed sensor; 7, the fuzzy PID controller, 11, the command speed signal generator, 12, the proportional amplifier; 13, the traction motor; 14, the frequency converter; 15, the current sensor; 16, comparator 1; 17, comparator 2; 18, comparator 3. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the preferred embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0039] As Figure 1As shown, a hydraulic control system for a walking part of a coal mining machine, including a coal mining machine frame, a hydraulic control part, a pin rail, a walking part, a walking wheel, a double-acting hydraulic cylinder, a traction motor, a fuzzy PID controller, a frequency converter; the double-acting hydraulic cylinder is arranged between the coal mining machine frame and the walking part, the walking part is hinged to the coal mining machine frame, the traction motor is connected with a current sensor, and a speed sensor is connected with a piston rod of the double-acting hydraulic cylinder; the hydraulic control part is configured to use the double-acting hydraulic cylinder to apply a force to the walking part when the coal mining machine starts working, the walking part is hinged to the coal mining machine frame and the guide shoe does not directly contact the pin rail, the walking part is slightly swung by the force to drive the walking wheel to quickly mesh with the pin rail, the speed sensor detects the speed of the piston movement and sends a speed signal difference, the current sensor is configured to collect current fluctuation signal differences of the two traction motors, the current fluctuation signal differences and the speed signal difference are processed together and sent to the fuzzy reasoning PID controller; the fuzzy reasoning PID controller is configured to adjust the movement of the double-acting hydraulic cylinder to complete synchronous quick meshing, and the frequency converter adjusts the rotating speed of the two traction motors until the two walking wheels are synchronously and quickly meshed.

[0040] As shown, Figure 2 As shown, a walking part quick meshing hydraulic control circuit schematic diagram, the elements in the circuit are an oil tank, a filter, a motor, a variable pump, an overflow valve, an electro-hydraulic servo valve, a check valve, a double-acting hydraulic cylinder, a speed sensor, a fuzzy PID controller, an instruction speed signal generator, and a comparator. The quick meshing hydraulic control circuit is realized by using a locking circuit composed of two hydraulic control check valves, the hydraulic control check valve can lock the piston rod at any position in the oil cylinder, the electro-hydraulic servo valve adopts a three-position four-way electro-hydraulic servo valve, the Y-shaped middle position is adopted, when it is in the middle position, the oil port is directly connected to the oil tank, the left and right oil paths of the oil cylinder are sealed by the check valve in the locking circuit, the piston rod stops moving and is locked; when it is in the left position, the pressure oil enters the rodless cavity of the oil cylinder through the check valve, pushes the piston rod to move to the right, and completes the meshing work of the walking wheel and the pin rail. The circuit has high locking precision and ensures that the walking wheel and the pin rail do not move relative to each other after meshing. The speed sensor detects the speed of the piston movement and sends a signal, the instruction speed signal generator sends a given speed signal, the signal and the speed signal detected by the speed sensor enter the comparator for operation, and then the speed signal difference enters the proportional amplifier, the proportional amplifier processes and transforms the speed signal difference and the current fluctuation signal difference into a unified signal, the unified signal is input to the fuzzy PID controller, and the fuzzy PID controller adjusts the working state of the electro-hydraulic servo valve to complete the quick meshing.

[0041] As shown, Figure 3The figure shows the schematic diagram of the hydraulic control circuit for the synchronous rapid engagement of the travel unit, which includes the travel wheel rapid engagement circuit, traction motor, current sensor, inverter, and fuzzy PID controller. The current sensor monitors the current fluctuations of the two traction motors in real time to determine whether the travel wheels are successfully synchronously engaged with the pin rail. If the current fluctuations are excessive or abnormal, the system determines that the travel wheels on both sides are not synchronously engaged with the pin rail. At this time, the current sensors on both sides detect the difference in current fluctuation signals. This current fluctuation signal difference, together with the speed signal difference, serves as the input of the fuzzy PID controller. The fuzzy PID controller controls the opening size and direction of the electro-hydraulic servo valve, outputs the corresponding pressure oil, drives the piston in the oil cylinder, and thus drives the travel unit to achieve synchronous rapid engagement.

[0042] like Figure 4 The figure shows the schematic diagram of the synchronous rapid engagement control system for the walking unit, which includes a traction motor, a frequency converter, a current sensor, a command signal generator, a comparator, a fuzzy PID controller, a proportional amplifier, an electro-hydraulic servo valve, a cylinder, and a speed sensor. These components form a closed-loop control circuit. The speed sensor detects the piston movement speed and sends the speed signal to comparator 1; the command speed signal generator sends a given signal, which is compared with the speed signal in comparator 1 and then sent to comparator 3; the current sensor detects the current fluctuation signal in the traction motor caused by the lack of synchronous engagement and calculates the current fluctuation signal difference in comparator 2, and the comparator 2 sends the current fluctuation signal difference to comparator 3; the comparator 3 sends the input speed signal difference and the current fluctuation signal difference together to the proportional amplifier, and the proportional amplifier converts the input signal into a unified signal and sends it to the fuzzy PID controller after amplification. The amplified unified signal is used as the controller input, and the fuzzy PID controller drives the piston movement in the oil cylinder by adjusting the working state of the electro-hydraulic servo valve and outputting hydraulic oil to act on the walking part. The walking part is subjected to force to generate a small swing, driving the walking wheel and the pin rail to achieve rapid engagement until the synchronous engagement of the walking parts on both sides is completed.

[0043] The speed sensor and current sensor are non-contact and do not come into direct contact with the measured components, thus preventing wear in actual working environments. The output of the speed sensor is fed as feedback into a comparator for comparison with a specified signal. After processing by the controller, it is fed into an amplifier to adjust the operating state of the flow control valve and regulate the flow, pressure, and direction of the circuit. The output of the current sensor is fed as feedback into the frequency converter to adjust the motor speed. If the two running parts are not synchronously engaged, the frequency converter adjusts the speed of the traction motors on both sides, appropriately increasing the speed of the non-engaged motor and reducing the speed of the engaged motor until synchronous and rapid engagement is achieved.

[0044] The commander is essentially a ramp signal generator. It sends a slowly rising or falling step signal. This step signal is dynamically adjusted with feedback from the speed sensor to ensure that the walking unit gradually swings and approaches the pin rail. This process strictly controls the speed to avoid shock caused by rapid contact and ensures smooth contact between the walking wheel and the pin rail.

[0045] like Figure 5 The figure shows the principle diagram of the walking unit synchronous fast meshing fuzzy PID controller. The fuzzy inference PID controller adopts fuzzy inference PID regulation, and uses fuzzy logic and certain fuzzy rules to adjust the PID parameter K in real time. p , K i and K d To overcome the shortcoming that traditional PID parameters cannot adjust PID parameters in real time, define K e is the gain of the controller error, K ec is the gain of the error change rate, de / dt is the derivative of the error with respect to time, K p , K i and K d By K e , K ec Two variables are controlled, and the fuzzy control part continuously updates the iterative K e , K ec These two variables improve the dynamic performance of the system, where K p , K i and K d The differential coefficient, proportional coefficient, and integral coefficient, respectively, are used to determine the differential coefficient, proportional coefficient, and integral coefficient. The fuzzy PID controller includes fuzzification, determining fuzzy rules, and defuzzification. The controller inputs a unified signal, performs fuzzy inference according to fuzzy inference rules, and finally defuzzifies it. It then outputs PID control parameters to adjust the operating state of the electromagnetic reversing valve. The transmitter receives feedback signals to adjust the control parameters. These components constitute a closed-loop control circuit.

[0046] like Figure 6 As shown in the figure, it is the structure diagram of fuzzy PID controller. Let K E ,K EC ,K P ,K I ,K D is the corresponding variable K e ,K ec ,K p ,K i ,K d The language variables are set as {NB (negative large), NM (negative medium), NS (negative small), ZO (zero), PS (positive small), PM (positive medium), PB (positive large)}. The domain is selected as {-6, -5, -4, -5, -2, -1, 0, 1, 2, 3, 4, 5, 6}, and the PID controller parameters are

[0047] K P =K P0 +ΔK P

[0048] K i =K i0 +ΔK i

[0049] K d =K d0 +ΔK d

[0050] Among them, K P0 , K i0 , K d0 As the initial value, the membership function chooses the classic trigonometric function.

[0051] The control idea of ​​fuzzy PID parameters is to eliminate the error as quickly as possible when the deviation is large; when the deviation is small, shrink the domain, relatively increase the fuzzy control rules, and suppress overshoot and oscillation.

[0052] like Figure 7 The figure shows a flow chart of the walking unit synchronous rapid engagement control system. The working method includes the following steps:

[0053] S1. Start the hydraulic system and initialize it. The variable displacement pump starts, pumping hydraulic oil from the tank to the hydraulic system, preparing to provide pressure. Set the hydraulic cylinder pressure to meet the system's thrust requirements for the travel wheels. If the pressure is below the set value, the pump flow rate is increased; if the pressure is above the set value, the relief valve opens to release excess pressure.

[0054] S2 receives sensor feedback signals (speed and current sensors), uses fuzzy PID to adjust the 4 / 3 electro-hydraulic servo valve, controls the movement direction and speed of the piston in the hydraulic cylinder, and fine-tunes the swing angle of the walking part so that the walking wheel gradually approaches the pin rail until it engages.

[0055] S3: Determine if meshing is in progress. Otherwise, proceed to step S2. If so, current fluctuations are detected to determine if synchronous meshing is in progress. If so, the system enters closed-loop control mode, continuously monitoring feedback from the speed and current sensors to ensure stable meshing of the travel unit. Otherwise, the system automatically adjusts the inverter and hydraulic cylinder for precise fine-tuning until synchronous meshing is achieved.

[0056] The above is only a preferred embodiment of the present application. It should be noted that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be considered as the scope of protection of the present application.

[0057] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications based on these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A hydraulic control system for the traveling part of a coal mining machine, characterized in that: include: Coal mining machine frame, hydraulic control unit, pin rail, travel unit, travel wheel, double-acting hydraulic cylinder, traction motor, fuzzy PID controller, frequency converter; The double-acting hydraulic cylinder is arranged between the coal mining machine frame and the walking part, the walking part is hinged to the coal mining machine frame, the traction motor is connected to the current sensor, and the speed sensor is connected to the piston rod of the double-acting hydraulic cylinder; The hydraulic control unit is configured to use a double-acting hydraulic cylinder to apply force to the walking unit when the coal mining machine starts working. The walking unit is hinged to the coal mining machine frame and the guide shoe is not in direct contact with the pin rail. The walking unit is subjected to force to generate a small angle α of swing, driving the walking wheel and the pin rail to achieve rapid engagement. The speed sensor detects the piston movement speed and sends a speed signal difference. The current sensor is configured to collect the current fluctuation signal difference of the traction motors on both sides, and the current fluctuation signal difference is processed together with the speed signal difference and then sent to the fuzzy inference PID controller; the fuzzy inference PID controller is configured to adjust the movement of the double-acting hydraulic cylinder to achieve synchronous rapid engagement, and the frequency converter adjusts the speed of the traction motors on both sides until the two travel wheels achieve synchronous rapid engagement; The hydraulic control unit includes a fast meshing hydraulic control circuit and a synchronous meshing hydraulic control circuit; wherein, The rapid engagement hydraulic control circuit includes an oil tank, a filter, a motor, a variable pump, a relief valve, an electro-hydraulic servo valve, a check valve, a double-acting hydraulic cylinder, a speed sensor, a fuzzy PID controller, a command speed signal generator, and a comparator; The quick engagement hydraulic control circuit is realized by a locking circuit composed of two hydraulically controlled one-way valves. The hydraulically controlled one-way valve can lock the piston rod at any position in the cylinder. The electro-hydraulic servo valve adopts a three-position four-way electro-hydraulic servo valve, and the middle position function adopts a Y-type. When it is in the middle position, the oil port is directly connected to the oil tank, the left and right oil circuits of the cylinder are blocked by the one-way valve in the locking circuit, and the piston rod stops moving and is locked; When it is in the left position, the pressure oil enters the rodless chamber of the oil cylinder through the one-way valve, pushing the piston rod to the right, completing the meshing of the travel wheel and the pin rail. After the travel wheel and the pin rail are meshed, no relative movement occurs. The speed sensor detects the piston movement speed and sends a signal. The command speed signal generator sends a given speed signal. This signal and the speed signal detected by the speed sensor enter the comparator for calculation and then send the speed signal difference to the proportional amplifier. The proportional amplifier processes the speed signal difference and the current fluctuation signal difference into a unified signal. The unified signal is used as the input of the fuzzy PID controller. The fuzzy PID controller adjusts the working state of the electro-hydraulic servo valve to complete rapid engagement. The synchronous meshing hydraulic control circuit includes a walking wheel fast meshing circuit, a traction motor, a current sensor, a frequency converter, a fuzzy PID controller, and a comparator; The current sensor monitors the current fluctuations of the two traction motors in real time to determine whether the traveling wheels are successfully and synchronously engaged with the pin rails. If the current fluctuations are too large or abnormal, the system determines that the traveling wheels on both sides are not synchronously engaged with the pin rails. At this time, the current sensors on both sides detect the current fluctuation signal difference. This current fluctuation signal difference and the speed signal difference are used as the input of the fuzzy PID controller. The fuzzy PID controller controls the opening size and direction of the electro-hydraulic servo valve, outputs the corresponding pressure oil, drives the piston movement in the oil cylinder, and then drives the traveling part to achieve synchronous and rapid engagement.

2. The hydraulic control system for the traveling part of a coal mining machine according to claim 1, characterized in that: The speed sensor detects the piston movement speed and sends the speed signal to comparator 1; the command speed signal generator sends a given signal, which is compared with the speed signal in comparator 1 and then sent to comparator 3; the current sensor detects the current fluctuation signal in the traction motor caused by the lack of synchronous engagement and calculates the current fluctuation signal difference in comparator 2, and the comparator 2 sends the current fluctuation signal difference to comparator 3; the comparator 3 sends the input speed signal difference and the current fluctuation signal difference together to the proportional amplifier, and the proportional amplifier converts the input signal into a unified signal and sends it to the fuzzy PID controller after amplification. The unified signal is used as the controller input, and the fuzzy PID controller drives the piston movement in the oil cylinder by adjusting the working state of the electro-hydraulic servo valve and outputting hydraulic oil to act on the walking part. The walking part is subjected to force to generate a small swing, driving the walking wheel and the pin rail to achieve rapid engagement until the synchronous engagement of the walking parts on both sides is completed.

3. The hydraulic control system for the traveling part of a coal mining machine according to claim 2, characterized in that: The output of the speed sensor is input as a feedback signal into the comparator for comparison with the specified signal, and then processed by the controller and sent to the amplifier to adjust the working state of the flow control valve, thereby adjusting the loop flow, pressure and direction; The output of the current sensor is sent to the frequency converter as a feedback signal to adjust the motor speed. When the walking parts on both sides are not synchronously engaged, the frequency converter adjusts the speed of the traction motors on both sides, increases the speed of the non-engaged motor, and reduces the speed of the engaged motor until synchronous and rapid engagement is achieved.

4. The hydraulic control system for the traveling part of a coal mining machine according to claim 3, characterized in that: The fuzzy inference PID controller adopts fuzzy inference PID regulation. When the deviation is large, the error is eliminated as soon as possible; when the deviation is small, the domain is narrowed and the fuzzy control rules are relatively increased to suppress overshoot and oscillation. Fuzzy logic is used to adjust the PID parameters Kp, Ki, and Kd in real time according to fuzzy rules. The establishment of the fuzzy PID includes fuzzification, determination of fuzzy rules, and defuzzification. The controller inputs a unified signal and then performs fuzzy inference according to fuzzy inference rules. Finally, the controller defuzzifies the signal and outputs the PID control parameters to adjust the working state of the electromagnetic reversing valve. The transmitter receives the feedback signal to adjust the control parameters. Among them, define K e is the gain of the controller error, K ec is the gain of the error change rate, de / dt is the derivative of the error with respect to time; K p ,K i ,K d By K e , K ec Two variables are controlled, and the fuzzy control part continuously updates the iterative K e , K ec These two variables, K p ,K i ,K d are the differential coefficient, proportional coefficient and integral coefficient respectively; The fuzzy inference PID adjustment includes: Let K E ,K EC ,K P ,K I ,K D is the corresponding variable K e ,K ec ,K p ,K i ,K d The language variables are set to {NB, NM, NS, ZO, PS, PM, PB}, the domain is selected to be {-6, -5, -4, -5, -2, -1, 0, 1, 2, 3, 4, 5, 6}, and the PID controller parameters are K P =K P0 +ΔK P K i =K i0 +ΔK i K d =K d0 +ΔK d Among them, K P0 , K i0 , K d0 As the initial value, the membership function chooses the classic trigonometric function.

5. The hydraulic control system for the traveling part of a coal mining machine according to claim 3, characterized in that: The command speed signal generator is a ramp signal generator, which sends a slowly rising or falling step signal. The step signal is dynamically adjusted with the feedback of the speed sensor, so that the walking part gradually swings and gradually approaches the pin rail until the walking wheel gently contacts the pin rail.

6. The hydraulic control system for the traveling part of a coal mining machine according to claim 3, characterized in that: The speed sensor and the current sensor are non-contact type and do not directly contact the measured element.

7. A working method, applied to the hydraulic control system for the traveling part of a coal mining machine according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Start the hydraulic system and initialize it. The variable displacement pump starts, transferring hydraulic oil from the tank to the hydraulic system to prepare for pressure. Set the hydraulic cylinder pressure value to meet the system's thrust requirements for the travel wheels. If the pressure is lower than the set value, increase the pump flow rate. If the pressure is higher than the set value, open the relief valve to release excess pressure. S2 receives feedback signals from speed and current sensors, uses fuzzy PID to adjust the three-position four-way electro-hydraulic servo valve, controls the movement direction and speed of the piston in the hydraulic cylinder, and fine-tunes the swing angle of the travel part, so that the travel wheel gradually approaches the pin rail until it engages; S3. Determine whether it is engaged. Otherwise, execute step S2. If yes, detect current fluctuation to determine whether it is synchronously engaged. If yes, enter closed-loop control mode and continuously monitor feedback from the speed sensor and current sensor to ensure that the walking part maintains stable engagement. Otherwise, automatically adjust the frequency converter and hydraulic cylinder to achieve precise fine-tuning until synchronous engagement.

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