Hydraulic control system for walking part of coal mining machine and working method of hydraulic control system

Abstract

The invention provides a hydraulic control system for a walking part of a coal mining machine and a working method thereof.The hydraulic control system comprises a coal mining machine rack, the walking part, a pin rail, walking wheels, a double-acting hydraulic cylinder, a traction motor, a fuzzy PID controller, a speed sensor and a current sensor, and the double-acting hydraulic cylinder is installed between the coal mining machine rack and the walking part; the walking part is driven to slightly swing through the telescopic movement of the hydraulic cylinder, so that the walking wheel and the pin rail quickly realize synchronous meshing when the coal mining machine is started, the controller receives feedback signals of the speed sensor and the current sensor in real time, and the movement of the hydraulic cylinder is dynamically adjusted according to the meshing state of the walking part, so that synchronous meshing of the walking wheel and the pin rail is ensured. A locking loop is further integrated, accurate locking of a piston at the meshing position is achieved through a hydraulic control one-way valve, relative sliding after meshing is prevented, output of a hydraulic cylinder is controlled and adjusted through fuzzy PID, the speed and the position of a walking wheel are intelligently adjusted, and automatic correction of the meshing problem is achieved.

Description

Technical Field

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

[0002] The existing coal mining machine travel control system has many limitations in the engagement of the travel wheel and the pin rail. It usually relies on mechanical drive and simple hydraulic adjustment. This method has poor adaptability to complex working conditions, resulting in problems such as asynchronous engagement and loose engagement under high load conditions.

[0003] Specifically, when the traveling wheel and the pin rail cannot engage synchronously, relative sliding of the traveling parts is likely to occur, resulting in increased wear of the coal mining machine's traveling system and reduced service life and reliability of the equipment.

[0004] In order to avoid these problems, coal mining equipment manufacturers and research institutions are committed to developing more intelligent hydraulic control systems to ensure that the traveling parts of the coal mining machine and the pin rail can achieve stable and synchronous rapid engagement under various working conditions. In current research, hydraulic control systems have become an important direction in the field of coal mining machine traveling parts control due to their fast response, large thrust and high control accuracy. 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 traveling parts according to feedback signals, thereby achieving precise synchronization between the traveling wheels and the pin rails. The key to this control system is to use sensors to monitor parameters such as pressure, speed, and displacement in real time, and to intelligently adjust the output of the hydraulic cylinder based on a closed-loop control mode to cope with the dynamic load requirements in complex mines. However, the existing hydraulic control system still has deficiencies in locking and closed-loop control, especially the design to prevent relative sliding after the traveling wheels and the pin rails are engaged is not perfect, which makes it easy to loosen after engagement, increasing the difficulty of system maintenance.

[0005] At the same time, with the improvement of the intelligence level of coal mining equipment, adaptive control algorithms such as fuzzy PID are gradually introduced into hydraulic control systems. Fuzzy PID control technology has strong robustness and adaptability. Through real-time adjustment of controller parameters, it can effectively cope with parameter fluctuations in the mine environment and further improve the accuracy of the meshing of the walking part. However, due to the complexity of the mine operating environment and the variability of working conditions, traditional PID control systems still have problems of response delay and insufficient adjustment when facing sudden load changes and parameter changes. Some studies have shown that with the assistance of multi-sensor feedback, more accurate synchronous control can be achieved by optimizing the fuzzy PID control algorithm, but this technology still needs a lot 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 being able to improve 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 a traveling part of a coal mining machine, including a coal mining machine body, 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 a 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 It is hinged 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 produce a small angle swing to drive 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 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 achieve synchronous rapid engagement, and the frequency converter adjusts the speed of the traction motors on both sides until the two walking wheels are synchronously and rapidly 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 circuit is realized by a locking circuit composed of two hydraulically controlled one-way valves, and the hydraulically controlled one-way valve can lock 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 circuit. 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 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 transforms the speed signal difference and the current 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 meshing hydraulic control circuit includes a walking wheel quick 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 walking wheels are successfully synchronously meshed with the pin rails. If the current fluctuations are too large or abnormal, the system determines that the walking wheels on both sides are not synchronously meshed with the pin rails. At this time, the current sensors on both sides detect the current signal difference, and this current 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 walking part to achieve synchronous and 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 comparator 1; the command speed 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 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 current 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 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 produce 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 a specified signal, and after being processed 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 preferred embodiment, the fuzzy inference PID controller adopts fuzzy inference PID adjustment. When the deviation is large, the error is eliminated as soon as possible; when the deviation is small, the domain is shrunk, and the fuzzy control rules are relatively increased to suppress overshoot and oscillation; 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 fuzzifies it 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 loop; wherein, the definition of K 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 is updated and iterated by K e , K ec These two variables, K p ,K i ,K dare the differential coefficient, proportional coefficient and integral coefficient respectively.

[0014] Preferably, 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 commander is a ramp signal generator, which sends out a slowly rising or falling step signal, and 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.

[0020] Preferably, the speed sensor and the current sensor are of 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 walking part, comprising the following steps:

[0022] S1. Start the hydraulic system and initialize it. The variable displacement pump starts to transfer the hydraulic oil from the oil tank to the hydraulic system and prepare to provide 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. If the pressure is higher than the set value, the relief valve opens to release excess pressure.

[0023] S2, receiving feedback signals from speed and current sensors, adjusting the 4 / 3 electro-hydraulic servo valve by fuzzy PID, controlling the movement direction and speed of the piston in the hydraulic cylinder, and fine-tuning the swing angle of the walking part, so that the walking wheel gradually approaches the pin rail until it engages;

[0024] 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, continuously monitor speed sensor and current sensor feedback to ensure that the walking part maintains stable engagement; otherwise, automatically adjust the inverter and hydraulic cylinder to achieve precise fine-tuning until synchronous engagement.

[0025] This application has the following beneficial effects:

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

[0027] 2. The hydraulic system uses a locking circuit composed of a hydraulically controlled one-way valve. After the meshing is completed, the piston rod can be stably locked at any position to prevent meshing failure caused by relative sliding after meshing. This design can maintain the stable operation of the walking part in harsh mining environments. Even under high loads or vibration shocks, the system can still effectively prevent meshing from loosening and improve operational reliability.

[0028] 3. The fuzzy PID controller dynamically adjusts the hydraulic cylinder pressure and movement direction based on the feedback signal, and can automatically correct the problem of asynchronous engagement. The control system combines multiple inputs such as speed sensors and current sensors to achieve full-process closed-loop control from the start of the walking part to the synchronous engagement. The fuzzy PID controller has strong anti-interference ability and robustness against load fluctuations and parameter changes that may occur in the system by adjusting the PID parameters in real time. It is particularly suitable for dynamic working conditions in complex mining environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are used to provide a 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 It is a structural schematic diagram of the synchronous rapid engagement of the traveling part of the coal mining machine.

[0031] Figure 2 It is the schematic diagram of the rapid engagement hydraulic control circuit of the traveling part of the coal mining machine.

[0032] Figure 3 It is the schematic diagram of the synchronous rapid engagement hydraulic control circuit of the traveling part of the coal mining machine.

[0033] Figure 4 This is the schematic diagram of the hydraulic control unit of the coal mining machine's traveling unit.

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

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

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

[0037] Among them, 1. Coal mining machine body; 2. Travel wheel; 3. Travel part; 4. Double-acting hydraulic cylinder; 5. Pin rail; 6. Traction motor; 7. Fuzzy PID controller; 8. Speed ​​sensor; 9. Current sensor; 10. Frequency converter; 21. Oil tank; 22. Filter; 23. Motor: 24. Variable pump: 25. Overflow valve; 26. Three-position four-way electro-hydraulic servo valve; 27. Check valve; 28. Oil cylinder; 29. ​​Speed ​​sensor; 7. Fuzzy PID controller, 11. Command speed signal generator, 12. Proportional amplifier; 13. Traction motor; 14. Frequency converter; 15. Current sensor; 16. Comparator 1; 17. Comparator 2; 18. Comparator 3. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the preferred embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0039] like Figure 1As shown, a hydraulic control system for a traveling part of a coal mining machine comprises a coal mining machine body, 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 a 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 is started, and the traveling part is hinged to the coal mining machine frame. The coal machine frame and the guide shoe are not in direct contact with the pin rail. The walking part is subjected to force to produce 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 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 synchronously and rapidly engaged.

[0040] like Figure 2 The figure shows the schematic diagram of the hydraulic control circuit for the quick engagement of the walking part. The components in the circuit include oil tank, filter, motor, variable pump, overflow valve, electro-hydraulic servo valve, check valve, double-acting hydraulic cylinder, speed sensor, fuzzy PID controller, command speed signal generator, and comparator. This quick engagement circuit is realized by a locking circuit composed of two hydraulically controlled check valves. The hydraulically controlled check 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, and the left and right oil circuits of the cylinder are blocked by the check 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 cylinder through the check valve, pushing the piston rod to the right, completing the meshing of the walking wheel and the pin rail. The locking accuracy of this circuit is high, ensuring that there is no relative movement after the walking wheel and the pin rail are engaged. The speed sensor detects the speed of the piston and sends a signal, instructing the speed signal generator to send a given speed signal. This signal and the speed signal detected by the speed sensor enter the comparator for calculation, and then the speed signal difference is sent to the proportional amplifier. The proportional amplifier processes the speed signal difference and the current signal difference into a unified signal, which 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.

[0041] like Figure 3The figure shows the schematic diagram of the hydraulic control circuit for synchronous rapid engagement of the walking part, including the walking wheel rapid engagement circuit, traction motor, current sensor, frequency converter, and fuzzy PID controller. 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, 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 signal difference. This current 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 walking part to achieve synchronous rapid engagement.

[0042] like Figure 4 As shown, it is a schematic diagram of the control system for synchronous rapid engagement of the walking part, including 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, an oil cylinder, and a speed sensor. The above parts constitute a closed-loop control circuit. The speed sensor detects the speed of the piston movement and sends the speed signal to the comparator 1; the command speed 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 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 signal difference to the proportional amplifier together, 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. The fuzzy PID controller drives the piston in the oil cylinder to move and act on the walking part by adjusting the working state of the electro-hydraulic servo valve and outputting hydraulic oil, and the walking part is forced to produce a small swing to drive 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 type and do not directly contact the measured components to avoid wear in the actual working environment; the output of the speed sensor can be used as a feedback signal to input the comparator to compare with the specified signal, and after being processed by the controller, it is sent to the amplifier to adjust the working state of the flow control valve and adjust the circuit flow, pressure and direction. The output of the current sensor is sent to the inverter as a feedback signal to adjust the motor speed. When the walking parts on both sides are not synchronously engaged, the inverter adjusts the speed of the traction motors on both sides, appropriately increases the speed of the non-engaged motor, and appropriately reduces the speed of the engaged motor until synchronous and rapid engagement is completed.

[0044] The commander is essentially a ramp signal generator. The commander sends a slowly rising or falling step signal. The step signal is dynamically adjusted with the feedback of the speed sensor to ensure that the walking part gradually swings and gradually approaches the pin rail. The speed is strictly controlled in this process to avoid impact caused by rapid contact and ensure soft contact between the walking wheel and the pin rail.

[0045] like Figure 5 The figure shows the schematic diagram of the synchronous fast meshing fuzzy PID controller for the walking part. 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 is updated and iterated by K e , K ec These two variables improve the dynamic performance of the system, where K p , K i and K d They are differential coefficient, proportional coefficient and integral coefficient respectively. The establishment of the fuzzy PID includes fuzzification, determination of fuzzy rules and defuzzification. The controller inputs a unified signal and then performs fuzzy reasoning according to the fuzzy reasoning rules, and finally defuzzifies it, outputs PID control parameters, adjusts the working state of the electromagnetic reversing valve, and the transmitter receives feedback signals to adjust the control parameters. The above parts 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 {NB (negative large), NM (negative medium), NS (negative small), ZO (zero), PS (positive small), PM (positive medium), PB (positive large)}. The domain is {-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 soon as possible when the deviation is large; when the deviation is small, shrink the domain, increase the fuzzy control rules relatively, and suppress overshoot and oscillation.

[0052] like Figure 7 The figure is a flow chart of the walking part synchronous rapid meshing control system, and the working method includes the following steps:

[0053] S1. Start the hydraulic system and initialize it. The variable displacement pump starts to transfer the hydraulic oil from the oil tank to the hydraulic system and prepare to provide 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; if the pressure is higher than the set value, the relief valve opens to release excess pressure.

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

[0055] S3, determine whether it is meshed, otherwise execute step S2, if yes, detect current fluctuation to determine whether it is synchronous meshing. If yes, enter closed-loop control mode, continuously monitor speed sensor and current sensor feedback to ensure that the walking part maintains stable meshing; otherwise, automatically adjust the inverter and hydraulic cylinder to achieve precise fine-tuning until synchronous meshing.

[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 principle of the present application, and these improvements and modifications should also be regarded 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, once knowing the basic creative concept, can make other changes and modifications according to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling 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 it. 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 recorded 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 a traveling part of a coal mining machine, characterized in that: include: Coal mining machine body, 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 swing to drive the walking wheel and the pin rail to achieve rapid meshing. 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 signal difference is processed together with the speed signal difference and then sent to the fuzzy inference PID controller; The fuzzy reasoning PID controller is configured to adjust the movement of the double-acting hydraulic cylinder to achieve synchronous rapid meshing, and the frequency converter adjusts the rotation speed of the traction motors on both sides until the synchronous rapid meshing of the two traveling wheels is achieved.

2. The hydraulic control system for the traveling part of a coal mining machine according to claim 1, characterized in that: The hydraulic control unit includes a fast meshing hydraulic control circuit and a synchronous meshing hydraulic control circuit; wherein, The fast-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 circuit is realized by a locking circuit composed of two hydraulically controlled one-way valves. The hydraulically controlled one-way valve can realize the locking of 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 cylinder through the one-way valve, pushing the piston rod to the right, completing the meshing of the travel wheel and the pin rail. No relative movement occurs after the travel wheel and the pin rail are meshed. 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 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.

3. The hydraulic control system for the traveling part of a coal mining machine according to claim 2, characterized in that: 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 synchronized with the pin rails. At this time, the current sensors on both sides detect the current signal difference. This current 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 in the oil cylinder to move, and then drives the traveling part to achieve synchronous and rapid engagement.

4. The hydraulic control system for the traveling part of a coal mining machine according to claim 3, characterized in that: 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 comparator 1; the command speed 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 meshing and calculates the current 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 current 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. The fuzzy PID controller adjusts the working state of the electro-hydraulic servo valve and outputs hydraulic oil to drive the piston movement in the cylinder and act on the walking part. The walking part is subjected to force to generate a small swing to drive the walking wheel and the pin rail to achieve rapid meshing until the synchronous meshing of the walking parts on both sides is completed.

5. The hydraulic control system for the traveling part of a coal mining machine according to claim 4, 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 after being processed by the controller, it 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 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 completed.

6. The hydraulic control system for the traveling part of a coal mining machine according to claim 5, 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, the fuzzy control rules are relatively increased, and overshoot and oscillation are suppressed; The PID parameters Kp, Ki and Kd are adjusted in real time according to fuzzy rules by using fuzzy logic. The establishment of the fuzzy PID includes fuzzification, determination of fuzzy rules and defuzzification. The controller inputs a unified signal and then performs fuzzy reasoning according to fuzzy reasoning rules, and finally defuzzifies it, outputs PID control parameters, adjusts the working state of the electromagnetic reversing valve, and the transmitter receives feedback signals to adjust the control parameters. The above parts constitute a closed-loop control circuit. Among them, define K 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 is updated and iterated by K e , K ec These two variables, K p ,K i ,K d are the differential coefficient, proportional coefficient and integral coefficient respectively.

7. The hydraulic control system for the traveling part of a coal mining machine according to claim 6, characterized in that: The fuzzy inference PID adjustment includes: Let 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 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.

8. The hydraulic control system for the traveling part of a coal mining machine according to claim 5, characterized in that: The commander is a ramp signal generator, which sends out 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.

9. The hydraulic control system for the traveling part of a coal mining machine according to claim 5, characterized in that: The speed sensor and the current sensor are non-contact type and do not directly contact the measured element.

10. 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 9, characterized in that: The following steps are involved: S1. Start the hydraulic system and initialize it. The variable displacement pump starts to transfer the hydraulic oil from the oil tank to the hydraulic system and prepare to provide 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. If the pressure is higher than the set value, the relief valve opens to release excess pressure. S2, receiving feedback signals from speed and current sensors, adjusting the 4 / 3 electro-hydraulic servo valve by fuzzy PID, controlling the movement direction and speed of the piston in the hydraulic cylinder, and fine-tuning the swing angle of the walking part, so that the walking 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, continuously monitor speed sensor and current sensor feedback to ensure that the walking part maintains stable engagement; otherwise, automatically adjust the inverter and hydraulic cylinder to achieve precise fine-tuning until synchronous engagement.

Images