Electro-hydraulic control speed regulation system and control method for threshing cylinder of combine harvester

Abstract

The invention provides an electro-hydraulic control speed regulation system for a threshing cylinder of a combine harvester and a control method. The electro-hydraulic control speed regulation system comprises an engine, a hydraulic system, a transmission rod, a speed regulation controller, the threshing cylinder, a rotating speed sensor and a three-way vibration sensor. The variable pump is driven by the engine, and an output shaft of the hydraulic motor is connected with the threshing cylinder through a transmission rod and used for driving the threshing cylinder to rotate. The rotating speed sensor is used for detecting the rotating speed of the threshing cylinder; the three-way vibration sensor is used for detecting the vibration amplitude of the threshing cylinder; the speed regulation controller generates a control signal based on PID operation according to signals output by the rotating speed sensor and the vibration sensor, controls the opening degree of the electromagnetic proportional flow valve and is used for automatic steady-speed regulation of the threshing cylinder. Proportional flow valve control and a double-sensor signal feedback mechanism are introduced, the problems that an existing roller driving system is slow in response and low in speed regulation precision are solved, and real-time stable control over the rotating speed of the roller is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of agricultural machinery and automation control technology, and particularly relates to an electro-hydraulic control speed regulation system and control method for a threshing cylinder of a combine harvester. BACKGROUND

[0002] As key equipment for realizing the mechanization of grain harvesting, the working performance of a combine harvester directly affects the efficiency of agricultural production and the quality of grain harvesting. A threshing device is a core working component of a combine harvester, and the rotational speed stability of a threshing cylinder is a key factor determining the threshing performance (including the threshing rate, the grain damage rate, and the loss rate caused by grain inclusion).

[0003] However, in actual field operation, the feeding amount, moisture content, grass-grain ratio of crops, and differences in crop varieties all cause the load torque acting on the threshing cylinder to fluctuate dramatically and frequently. Such load fluctuation causes the rotational speed of the cylinder to drop or overshoot, which in turn causes a series of problems: when the rotational speed is too low, the threshing is not complete, and the loss caused by grain inclusion increases; when the rotational speed is too high, the grains are impacted and damaged, the breakage rate increases, and the energy consumption rises. Therefore, achieving constant-speed stable control of the threshing cylinder under variable load working conditions is a core technical problem for improving the working quality and efficiency of a combine harvester.

[0004] Traditional threshing cylinder driving mode mostly adopts mechanical transmission or quantitative hydraulic system. The mechanical transmission driving system usually adopts V-belt or chain transmission, and power is transmitted to the threshing cylinder through mechanical structures such as clutch, gearbox and the like from the engine. The advantages are simple structure, low cost and high transmission efficiency. However, the disadvantages are particularly prominent: firstly, the speed regulation process is tedious, and manual replacement of pulley or sprocket is usually required, so that real-time speed regulation cannot be realized in operation; secondly, the response of the system to load change completely depends on the speed-torque characteristics of the engine, and when the load suddenly increases, the engine speed decreases, and the synchronous decrease of the cylinder speed is directly caused by the rigid transmission mechanism, lacking effective buffer and compensation mechanism, and the dynamic response characteristics are poor. This mode has been difficult to meet the high requirements of modern precision agriculture on operation quality. Compared with mechanical transmission, the quantitative hydraulic driving system adopts a hydraulic circuit of “fixed displacement pump + fixed displacement motor” or “fixed displacement pump + variable displacement motor”, and realizes stepless speed regulation of the cylinder by adjusting the displacement of the pump or the displacement of the motor. Compared with mechanical transmission, it simplifies the transmission structure and is more convenient to operate. However, the core defect of the quantitative hydraulic driving system in the prior art is the open-loop or semi-closed-loop characteristics of the control mode. The response of the hydraulic flow and pressure output by the system to load change has inherent hysteresis, and when the load torque increases, the increase of the system pressure will cause the volumetric efficiency of the pump and motor to decrease and the internal leakage to increase, thereby causing the “drop” of the output speed of the hydraulic motor, i.e. the so-called “speed rigidity” deficiency. Simple feedback control is often slow in response and cannot compensate for the speed fluctuation caused by load disturbance in time, resulting in unsatisfactory cylinder speed stability.

[0005] The driving system of the threshing cylinder in the prior art, whether mechanical or quantitative hydraulic, cannot achieve the best effect in response speed and control accuracy when dealing with complex and variable field operation loads. SUMMARY

[0006] In view of the deficiencies in the prior art, the present application provides an electro-hydraulic control speed regulation system and control method for a threshing cylinder of a combine harvester, which introduces a proportional flow valve control and a double sensor signal feedback mechanism to solve the problems of slow response and low speed regulation accuracy of the existing cylinder driving system, and realizes real-time stable control of the cylinder speed.

[0007] The present application achieves the above technical purposes through the following technical means.

[0008] An electro-hydraulic control speed regulation system for a threshing cylinder of a combine harvester, comprising an engine, a hydraulic system, a transmission rod, a speed regulator, a threshing cylinder, a speed sensor and a three-way vibration sensor;

[0009] The hydraulic system comprises a hydraulic oil tank, a variable pump, an overflow valve, an electromagnetic proportional flow valve and a hydraulic motor; the variable pump is driven by the engine, the variable pump is connected with the electromagnetic proportional flow valve and the hydraulic motor in sequence, the output shaft of the hydraulic motor is connected with the threshing cylinder through a transmission rod for driving the threshing cylinder to rotate; the rotation speed sensor is used for detecting the rotation speed of the threshing cylinder; the three-way vibration sensor is used for detecting the vibration amplitude of the threshing cylinder;

[0010] The speed regulation controller receives the rotation speed sensor, the three-way vibration sensor and the electromagnetic proportional flow valve signal; the speed regulation controller generates a control signal based on the PID operation according to the signals output by the rotation speed sensor and the vibration sensor, controls the opening degree of the electromagnetic proportional flow valve, and is used for automatic speed regulation of the threshing cylinder.

[0011] Further, the electromagnetic proportional flow valve is an analog proportional valve with electric feedback function.

[0012] Further, the speed regulation controller adopts a double closed loop PID control structure, wherein the outer ring takes the rotation speed error of the threshing cylinder as the input, and the inner ring takes the opening degree or control current of the electromagnetic proportional flow valve as the control quantity.

[0013] Further, when the vibration amplitude detected by the three-way vibration sensor exceeds a preset threshold, the speed regulation controller automatically increases the opening degree of the proportional valve, and increases the output torque of the hydraulic motor to compensate for the decrease of the rotation speed of the cylinder.

[0014] Further, the overflow valve is arranged in the main oil circuit of the hydraulic system and is used for limiting the maximum pressure of the system.

[0015] Further, the speed regulation controller, the electromagnetic proportional flow valve, the rotation speed sensor and the three-way vibration sensor communicate through the CAN bus.

[0016] Further, the hydraulic motor is a constant displacement hydraulic motor, and the variable pump adjusts the system flow by changing the displacement, so as to realize the rotation speed control of the threshing cylinder.

[0017] A control method of an electro-hydraulic control speed regulation system for a threshing cylinder of a combine harvester, comprising the following steps:

[0018] Setting a target rotation speed of the threshing cylinder;

[0019] Collecting the rotation speed signal of the threshing cylinder in real time through the rotation speed sensor;

[0020] Collecting the vibration signal of the threshing cylinder in real time through the three-way vibration sensor;

[0021] The speed regulation controller receives the rotation speed signal and the vibration signal;

[0022] The speed regulating controller compares the collected rotating speed with a target rotating speed, and judges whether the vibration signal exceeds a preset threshold value;

[0023] The speed regulating controller performs PID operation and feedforward compensation calculation based on rotating speed error and in combination with the judgment result of the vibration signal, to generate a control signal;

[0024] The control signal is output to an electromagnetic proportional flow valve, the opening of which is adjusted, so as to change the flow of hydraulic oil driving the hydraulic motor, and realize closed-loop stable control of the rotating speed of the threshing cylinder.

[0025] The present application has the following advantages:

[0026] 1. The electro-hydraulic control speed regulating system and control method for the threshing cylinder of a combine harvester, by introducing signal monitoring of a three-way vibration sensor on the basis of traditional closed-loop control, realizes feedforward compensation control of load variation. When the threshing cylinder is subjected to sudden increase in feeding amount or change in crop hardness and other disturbances, the vibration signal will respond first before the rotating speed decreases. The speed regulating controller can identify the load fluctuation trend in advance according to the vibration amplitude and frequency spectrum change, output a correction control signal before the rotating speed of the cylinder deviates, adjust the opening of the proportional valve, and quickly increase the hydraulic flow and motor output torque, so as to offset the load impact in advance and realize the advanced response control of the system. Compared with the conventional PID closed-loop regulation mode relying only on rotating speed feedback, the system is significantly shortened in dynamic response time, and has stronger real-time performance and anti-disturbance ability.

[0027] 2. The electro-hydraulic control speed regulating system and control method for the threshing cylinder of a combine harvester, adopts a control strategy of fusion of vibration and rotating speed dual sensing signals, realizes accurate hydraulic power matching through decoupling of multiple source signals and dynamic weighting of PID algorithm in the speed regulating controller. The rotating speed sensor provides the basis for closed-loop control of the steady-state rotating speed of the cylinder, and the vibration sensor provides the feedforward signal of the running state of the cylinder, so that the control system can take into account "fast response" and "stable control" when the load fluctuates. The electromagnetic proportional flow valve realizes continuous flow regulation according to the analog current signal output by the controller, avoiding the lag and overshoot problems of traditional hydraulic systems. The dual-signal cooperative control mechanism can control the rotating speed fluctuation amplitude of the cylinder within the set range, and significantly improves the speed control accuracy and system stability of the threshing cylinder under complex working conditions.

[0028] 3. The electro-hydraulic control speed regulation system and control method for a combined harvester cylinder according to the present application, which is based on the modular upgrade of the existing combined harvester hydraulic drive system. Only by adding an electromagnetic proportional flow valve and a sensor module between the variable pump and the hydraulic motor, the electro-hydraulic proportional speed regulation function of the whole machine can be realized. The controller adopts an integrated design, with signal acquisition, data filtering, PID operation and CAN bus communication functions, without the need for additional complex mechanical or electrical structures. The three-way vibration sensor and the rotational speed sensor can be directly installed on the cylinder or its support position without changing the original arrangement space. This structural scheme is convenient for popularization and application on different types of combined harvesters, can realize plug-and-play control system upgrade, and significantly reduces the modification cost and system integration difficulty. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. The drawings described in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0030] Figure 1 The electro-hydraulic control speed regulation system for a combined harvester cylinder according to the present application.

[0031] Figure 2 The hydraulic system principle diagram according to the present application.

[0032] Figure 3 The system control principle diagram according to the present application.

[0033] In the drawings:

[0034] 1 - engine; 2 - hydraulic system; 201 - hydraulic oil tank; 202 - variable pump; 203 - overflow valve; 204 - electromagnetic proportional flow valve; 205 - hydraulic motor; 3 - transmission rod; 4 - speed regulation controller; 5 - cylinder; 6 - rotational speed sensor; 7 - three-way vibration sensor. DETAILED DESCRIPTION

[0035] The embodiments of the present application will be described in detail below, and the examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0036] In the description of the present application, it needs to be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "axial", "radial", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can be explicitly or implicitly included one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0037] In the present application, unless otherwise specifically defined and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0038] As Figure 1 The electro-hydraulic control speed regulating system for the threshing cylinder of the combine harvester of the present application comprises an engine 1, a hydraulic system 2, a transmission rod 3, a speed regulating controller 4, a threshing cylinder 5, a rotating speed sensor 6 and a three-way vibration sensor 7.

[0039] The hydraulic system 2 comprises a hydraulic oil tank 201, a variable pump 202, an overflow valve 203, an electromagnetic proportional flow valve 204 and a hydraulic motor 205; the engine 1 drives the variable pump 202, the variable pump 202 is connected with the electromagnetic proportional flow valve 204 and the hydraulic motor 205 in sequence, the output shaft of the hydraulic motor 205 is connected with the threshing cylinder 5 through the transmission rod 3, for driving the threshing cylinder 5 to rotate; the output rotating speed of the hydraulic motor is the working rotating speed of the cylinder. The rotating speed sensor 6 is installed at the shaft end of the cylinder, for detecting the rotating speed of the threshing cylinder 5; the three-way vibration sensor 7 is installed on the cylinder frame or support seat, for detecting the vibration amplitude of the threshing cylinder 5; the hydraulic motor 205 is a constant displacement hydraulic motor, the variable pump 202 adjusts the system flow by changing the displacement, so as to realize the rotating speed control of the threshing cylinder 5.

[0040] As Figure 3As shown, the speed controller 4 receives the speed sensor 6, three-way vibration sensor 7 and electromagnetic proportional flow valve 204 signals; the speed controller 4 generates a control signal based on the PID operation according to the signals output by the speed sensor 6 and the vibration sensor 7, controls the opening of the electromagnetic proportional flow valve 204, and then changes the output speed of the hydraulic motor 205 to realize dynamic control of the drum speed. The speed controller 4, electromagnetic proportional flow valve 204, speed sensor 6 and three-way vibration sensor 7 communicate through the CAN bus.

[0041] As shown in Figure 2 , the engine 1 drives the variable pump 202 through the shaft coupling, and the variable pump output is connected to the electromagnetic proportional flow valve 204. The outlet of the proportional valve 204 is connected to the hydraulic motor 205 through the high-pressure oil pipe, and the hydraulic motor outputs mechanical power, which is transmitted to the threshing drum 5 through the transmission rod 3.

[0042] The hydraulic system adopts a closed loop structure, and an overflow valve 203 is provided on the main oil circuit for maintaining stable system pressure and preventing overpressure damage. The oil return port returns to the hydraulic oil tank 201 through the oil pipe. The electromagnetic proportional flow valve 204 and the speed controller 4 are connected by electricity, and the controller outputs control current according to the feedback signal to realize linear regulation of the proportional valve. The electro-hydraulic composite speed regulation structure can realize continuous variable speed regulation, has short response time, high energy utilization rate, and is suitable for different crops and working conditions under different threshing load changes.

[0043] The speed controller 4 adopts a double closed loop PID control structure, wherein the outer ring takes the threshing drum speed error as the input, and the inner ring takes the opening or control current of the electromagnetic proportional flow valve as the control quantity. When the vibration amplitude detected by the three-way vibration sensor 7 exceeds the preset threshold, the speed controller 4 automatically increases the opening of the proportional valve 204 to compensate for the decrease in drum speed by increasing the output torque of the hydraulic motor 205.

[0044] The specific PID control algorithm in the speed controller 4 is as follows:

[0045] The final output control quantity u(k) of the controller is composed of the standard PID feedback control quantity and the feedforward compensation quantity based on the vibration signal:

[0046]

[0047] Wherein: is the standard PID feedback control quantity; is the feedforward compensation quantity based on the vibration signal; k represents the time when it is used;

[0048] The calculation of the standard PID feedback control quantity is as follows: the standard PID control algorithm adopts a positional PID formula, and its discrete expression is:

[0049]

[0050] wherein:

[0051] is the standard PID feedback control quantity at the kth sampling moment.

[0052] e(k) is the rotational speed error at the kth sampling moment, e(k)=n set −n actual (k), n set is the set rotational speed, n actual (k) is the rotational speed actually measured by the rotational speed sensor 6 at the kth sampling moment. e(k-1) is the rotational speed error at the (k-1)th sampling moment;

[0053] Kp, Ki, Kd are the proportional, integral, and differential coefficients, respectively;

[0054] is the cumulative value of the error at the kth sampling moment;

[0055] T s is the sampling period.

[0056] The determination of the feedforward compensation quantity is as follows:

[0057] The feedforward compensation mechanism is based on the signal of the three-direction vibration sensor 7. The controller calculates the total vibration amplitude A vib (k) after the synthesis of the three-direction vibration vector in real time. When A vib (k) exceeds the preset vibration threshold A threshold , the feedforward compensation is triggered.

[0058] The determination of the feedforward compensation quantity ,

[0059] wherein: K f is the feedforward compensation gain coefficient.

[0060] At the moment t k =k⋅T s , the controller calculates u(k) and outputs the corresponding analog voltage or current signal through the D / A converter. The output signal will remain unchanged throughout the next sampling period [k⋅Ts,(k+1)⋅Ts) and act on the electromagnetic proportional flow valve 204, thereby realizing continuous control of the opening degree of the electromagnetic proportional flow valve 204 and achieving continuous and smooth adjustment of the rotational speed of the hydraulic motor 205.

[0061] The compound control algorithm of the speed controller 4 effectively makes up for the defect of response lag of the traditional PID closed-loop control, so that the system can quickly act when the load is suddenly changed, and the rotating speed of the cylinder is maintained stable.

[0062] The control method of the electro-hydraulic control speed regulation system for the cylinder of the combine harvester comprises the following steps:

[0063] Setting a target rotating speed n of the cylinder set ;

[0064] Collecting a rotating speed signal n of the cylinder 5 in real time through a rotating speed sensor 6 actual (k);

[0065] Collecting a vibration signal A of the cylinder 5 in real time through a three-way vibration sensor 7 vib (k);

[0066] The speed controller 4 receives the rotating speed signal and the vibration signal;

[0067] The speed controller 4 compares the collected rotating speed with the target rotating speed, and judges whether the vibration signal exceeds a preset threshold value;

[0068] The speed controller 4 performs PID operation and feedforward compensation calculation based on the rotating speed error and in combination with the judgment result of the vibration signal, and generates a control signal;

[0069] The control signal is output to an electromagnetic proportional flow valve 204, the opening of the electromagnetic proportional flow valve 204 is adjusted, so that the hydraulic oil flow of a driving hydraulic motor 205 is changed, and closed-loop stable control of the rotating speed of the cylinder 5 is realized.

[0070] When the vibration signal amplitude exceeds the set threshold value or the vibration spectrum changes abnormally, the controller judges that the system will face a sudden load change, and the output current is adjusted in advance, the opening of the proportional valve 204 is increased, and the flow output of the variable pump 202 is increased, so as to compensate for the possible rotating speed drop. The feedforward compensation mechanism effectively makes up for the defect that the traditional closed-loop control only relies on rotating speed feedback and has response lag, so that the cylinder rotating speed control is more stable and real-time, and especially in the working condition that the impurity content is high or the crop humidity changes greatly, the system can still maintain stable threshing efficiency.

[0071] It should be understood that although the present specification is described in terms of various embodiments, not every embodiment contains only one independent technical solution, and the description manner of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other implementation manners that those skilled in the art can understand.

[0072] The above detailed description merely illustrates feasible embodiments of the present application, and is not intended to limit the protection scope of the present application, and equivalent embodiments or changes made without departing from the spirit of the present application shall be included in the protection scope of the present application.

Claims

1. An electro-hydraulic speed control system for a combine harvester threshing drum, characterized in that, It includes an engine (1), a hydraulic system (2), a transmission rod (3), a speed controller (4), a threshing drum (5), a speed sensor (6), and a three-dimensional vibration sensor (7). The hydraulic system (2) includes a hydraulic oil tank (201), a variable pump (202), an electromagnetic proportional flow valve (204), and a hydraulic motor (205); the engine (1) drives the variable pump (202), which is connected in sequence to the electromagnetic proportional flow valve (204) and the hydraulic motor (205). The output shaft of the hydraulic motor (205) is connected to the threshing drum (5) through a transmission rod (3) to drive the threshing drum (5) to rotate; the speed sensor (6) is used to detect the speed of the threshing drum (5); the triaxial vibration sensor (7) is used to detect the vibration amplitude of the threshing drum (5). The speed controller (4) receives signals from the speed sensor (6), the triaxial vibration sensor (7) and the electromagnetic proportional flow valve (204); the speed controller (4) generates a control signal based on PID calculation according to the signals output by the speed sensor (6) and the vibration sensor (7), and controls the opening of the electromagnetic proportional flow valve (204) for automatic speed regulation of the threshing drum (5).

2. The electro-hydraulic speed control system for a combine harvester threshing drum according to claim 1, characterized in that, The electromagnetic proportional flow valve (204) is an analog proportional valve with electrical feedback function.

3. The electro-hydraulic speed control system for a combine harvester threshing drum according to claim 1, characterized in that, The speed controller (4) adopts a dual closed-loop PID control structure, wherein the outer loop takes the speed error of the threshing drum as input, and the inner loop takes the opening degree of the electromagnetic proportional flow valve or the control current as control quantity.

4. The electro-hydraulic speed control system for a combine harvester threshing drum according to claim 1, characterized in that, When the vibration amplitude detected by the triaxial vibration sensor (7) exceeds the preset threshold, the speed controller (4) automatically increases the opening of the proportional valve (204) and increases the output torque of the hydraulic motor (205) to compensate for the decrease in drum speed.

5. The electro-hydraulic control speed regulation system for the threshing drum of a combine harvester according to claim 1, characterized in that, The relief valve (203) is located in the main oil circuit of the hydraulic system (2) to limit the maximum pressure of the system.

6. The electro-hydraulic control speed regulation system for a combine harvester threshing drum according to claim 1, characterized in that, The speed controller (4), electromagnetic proportional flow valve (204), speed sensor (6) and triaxial vibration sensor (7) communicate via CAN bus.

7. The electro-hydraulic speed control system for a combine harvester threshing drum according to claim 1, characterized in that, The hydraulic motor (205) is a fixed-displacement hydraulic motor, and the variable pump (202) adjusts the system flow by changing the displacement, thereby realizing the speed control of the threshing drum (5).

8. A control method for an electro-hydraulic speed control system for a combine harvester threshing drum according to any one of claims 1-7, characterized in that, Includes the following steps: Set the target rotation speed of the threshing drum; The rotational speed signal of the threshing drum (5) is collected in real time by the rotational speed sensor (6); The vibration signal of the threshing drum (5) is collected in real time by a three-dimensional vibration sensor (7); The speed controller (4) receives the speed signal and vibration signal; The speed controller (4) compares the collected rotational speed with the target rotational speed and determines whether the vibration signal exceeds the preset threshold. The speed controller (4) generates a control signal by performing PID calculation and feedforward compensation calculation based on the speed error and the judgment result of the vibration signal. The control signal is output to the electromagnetic proportional flow valve (204) and its opening is adjusted to change the hydraulic oil flow of the driving hydraulic motor (205) and realize closed-loop stable control of the rotation speed of the threshing drum (5).

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