Electric suspension system of tractor matched with rotary cultivator and control method of electric suspension system

Abstract

The invention belongs to the technical field of electric suspension control of tractors, and particularly relates to an electric suspension system of a tractor matched with a rotary cultivator and a control method of the electric suspension system. The system comprises a fuel cell, a power cell, a fuel cell controller, a power cell controller, a high-voltage distribution box, a DC / DC converter, a whole machine controller, a control panel, a force sensor used for measuring tillage resistance during operation of the rotary cultivator, a tilt angle sensor used for measuring the tilt angle of a universal joint of the rotary cultivator, an angular displacement sensor, a servo electric cylinder, a lifting pull rod and a lifting rod. A lower pull rod; operation parameters of the rotary cultivator are input through the control panel, the sensors transmit the measured parameters to the whole machine controller, the comprehensive tilling depth is calculated according to the position of the electric cylinder and the soil resistance, the servo electric cylinder is controlled to stretch out and draw back according to the comparison between the comprehensive tilling depth and the preset tilling depth, and therefore the tilling depth of the rotary cultivator is adjusted. The device has the advantages of being simple in structure, convenient to maintain and high in applicability.

Description

Technical Field

[0001] The invention belongs to the technical field of tractor electric suspension control, and in particular relates to an electric suspension system of a tractor matched with a rotary tiller and a control method thereof, which are used for adjusting the height of the rotary tiller. Background Art

[0002] A rotary tiller is a tilling machine used in conjunction with a tractor. It is mainly used for soil tillage, weed removal and soil leveling and is widely used by farmers. In Jiangsu Province alone, the utilization rate of rotary tillers accounts for 75.8% of all tillage machinery. The rotary tiller needs to be adjusted mechanically according to different land environments, crops, and depths, including the tillage depth of the rotary tiller and the inclination of the universal joint. Adjusting the tillage depth of the rotary tiller by controlling the tractor's three-point suspension will directly affect the quality of the operation.

[0003] At present, most tractors use hydraulic suspension systems to adjust the tillage depth of rotary tillers, which has problems such as low efficiency, frequent failures, and complex structures. The tillage depth cannot be adjusted in real time as the terrain changes, and the hydraulic suspension cannot well guarantee the quality of rotary tillage operations and cannot meet the better economy of agricultural machinery. Based on energy saving, improving tillage quality, and the research and development of electric agricultural machinery for tractors, a series of improvements can be made to the electric suspension of tractors to achieve control of the tillage depth of rotary tillers. The electric suspension has a simple structure, low energy consumption, clean energy and emissions, and can achieve tillage depth adjustment through force adjustment, position adjustment, and force-position combined adjustment. It can also introduce PID control algorithms and other methods to achieve control of the electric suspension, so it has a better development prospect. Summary of the invention

[0004] In order to solve the technical problem that the height of the rotary tiller is difficult to adjust, the present invention provides an electric suspension system for a tractor matched with a rotary tiller and a control method thereof, which can adjust the suspension to change the height of the rotary tiller according to the tillage conditions when the rotary tiller is in rotary tillage operation.

[0005] To achieve the above-mentioned purpose, the present invention provides an electric suspension system of a tractor matched with a rotary tiller, comprising a servo electric cylinder hinged on a tractor frame, a lifting arm hinged on an output shaft of the servo electric cylinder, a lifting rod hinged on the lifting arm, a lower rod hinged on the lifting rod, a three-point suspension hinged on the lower rod, and a rotary tiller connected to the three-point suspension through a universal joint, wherein the lifting arm is hinged on the tractor frame, the hinge point of the servo electric cylinder output shaft and the lifting arm is located between the lifting arm and the tractor frame and the hinge point of the lifting rod, the lower rod is hinged on the tractor frame, the three-point suspension is hinged on the tractor frame, and the hinge point between the lifting rod and the lower rod is located between the lower rod and the tractor frame and the hinge point of the three-point suspension;

[0006] Angular displacement sensors are arranged at the hinged positions of the servo electric cylinder, lifting arm, lower pull rod and tractor frame, force sensors are also arranged at the hinged positions of the lower pull rod and tractor frame, and an inclination sensor is arranged on the universal joint. The angular displacement sensor, force sensor, inclination sensor and servo electric cylinder are communicatively connected with the whole machine controller, and the whole machine controller is communicatively connected with the control panel.

[0007] Furthermore, it also includes a fuel cell and a fuel cell controller for powering a tractor, a rotary tiller, a servo electric cylinder, an angular displacement sensor, a force sensor, and an inclination sensor, and the fuel cell controller is communicatively connected with the whole machine controller.

[0008] Furthermore, it also includes a power battery and a power battery controller for supplementing power supply, and the power battery controller is communicatively connected with the whole machine controller.

[0009] Furthermore, the fuel cell and power battery are electrically connected to the corresponding DC / DC converter, the DC / DC converter is electrically connected to the high-voltage distribution box, and the high-voltage distribution box is electrically connected to the tractor, rotary tiller, servo electric cylinder, angular displacement sensor, force sensor, and inclination sensor.

[0010] Furthermore, the force sensor is a pin-type force sensor, which is installed at the pin hole where the lower pull rod is hinged to the frame.

[0011] Furthermore, the measuring surface of the force sensor and the force-bearing surface of the lower pull rod are on the same horizontal plane.

[0012] A control method for an electric suspension system of a tractor matched with a rotary tiller comprises the following steps:

[0013] S1. Before the rotary tillage operation begins, the tractor sets the preset tillage depth value h of the rotary tiller through the control panel, and the whole machine controller receives the signal output by the control panel;

[0014] S2, start the tractor to move. During this process, the force sensor measures the soil resistance of the rotary tiller, the inclination sensor measures the angle of the universal joint, and the angular displacement sensor measures the angular displacement of the lifting arm, the lower pull rod, and the servo electric cylinder, and inputs the measured data into the whole machine controller;

[0015] S3. The whole machine controller calculates the force tillage depth H1 according to the soil resistance measured by the force sensor, and converts the position tillage depth H2 according to the telescopic stroke of the servo electric cylinder. The PID controller I adjusts the comprehensive proportional coefficient, and obtains the comprehensive tillage depth H measured by the force-position comprehensive adjustment through weight calculation. The PID controller II calculates the tillage depth control variable value, controls the telescopic action of the servo electric cylinder, and adjusts the tillage depth of the rotary tiller in real time.

[0016] S4. When the tractor is in a turning or stopped tilling condition, the whole machine controller receives the signal transmitted by the inclination sensor, controls the height of the rotary tiller, and limits the telescopic stroke of the servo electric cylinder.

[0017] S5, repeat S2 and S3 until the rotary tillage operation is completed.

[0018] Furthermore, the relationship between the tillage depth H1 and soil resistance is obtained by the following formula:

[0019]

[0020] In formula (1),

[0021] F is the soil resistance, measured by the force sensor;

[0022] k1 is the soil specific resistance, which can be determined according to different working environments;

[0023] b is the tillage width, which is obtained from the rotary tiller parameters and actual tillage conditions.

[0024] Furthermore, the relationship between the telescopic stroke of the servo electric cylinder and the tillage depth H of the rotary tiller determined according to the electric suspension operation model is as follows:

[0025]

[0026] In formula (2),

[0027] h1 is the vertical distance from the hinge point between the rotary tiller and the tractor to the horizontal plane of the lowest working point of the rotary tiller's rotary blade, which is a fixed value;

[0028] h2 is the vertical distance from the hinge point between the lower tie rod and the frame to the ground, which is a fixed value;

[0029] k1 is the ratio of the length of the lower pull rod to the length from the hinge position of the servo electric cylinder on the lifting arm to the hinge position of the frame, which is a fixed value;

[0030] S is the telescopic stroke of the servo cylinder;

[0031] α DN is the angle between the pull-down rod and the horizontal plane;

[0032] α PQ is the angle between the servo electric cylinder and the horizontal plane;

[0033] α OM It is the angle between the lifting arm and the horizontal plane.

[0034] Furthermore, the comprehensive tillage depth H is obtained from the force-position comprehensive adjustment mode:

[0035] H=aH1+(1-a)H2 (3)

[0036] In formula (3),

[0037] a is the comprehensive proportional coefficient, which is adjusted in real time by the PID controller according to soil resistance, and its value is 0≤a≤1.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) Using power batteries to fill the power requirements of the rotary tiller that cannot be provided by fuel cells can effectively reduce costs compared to single fuel cells or supercapacitors;

[0040] (2) Compared with traditional hydraulic suspension, electric suspension can make use of the servo motor brake characteristics and three-point suspension to achieve reliable fixation of the rotary tiller, simple structure, and ensure uniform tillage depth of the rotary tiller;

[0041] (3) The use of the force-position comprehensive adjustment method and the resistance-type automatic adjustment comprehensive proportional coefficient enables the rotary tiller to till the soil in an environment with changing soil resistance and terrain undulations, with good tillage depth control effect;

[0042] (4) The PID tillage depth controller is used to compare the actual tillage depth value obtained by comprehensive force-position adjustment with the set tillage depth value, and the tillage depth of the rotary tiller is controlled. It has excellent adaptability and good robustness. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the overall structure of an embodiment of an electric suspension system of a tractor matched with a rotary tiller according to the present invention;

[0044] Figure 2 A schematic diagram of an electric suspension system of a tractor matched with a rotary tiller according to an embodiment of the present invention;

[0045] Figure 3 This is a schematic diagram of an operating model of an electric suspension and a rotary tiller of an embodiment of an electric suspension system of a tractor matched with a rotary tiller of the present invention.

[0046] [Reference Signs]

[0047] 1. Control panel; 2. Machine controller; 3. High-voltage distribution box; 4. Angular displacement sensor; 5. Lifting arm; 6. Lifting rod; 7. Tilt sensor; 8. Rotary tiller; 9. Lower rod; 10. Axis pin force sensor; 11. Servo cylinder; 12. DC / DC converter; 13. Power battery; 14. Power battery controller (BMS); 15. Fuel cell; 16. Fuel cell controller (FCU). DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] See also Figure 1 to Figure 2 An electric suspension control system for a low-horsepower fuel cell tractor used in conjunction with a rotary tiller, hereinafter referred to as the system, is improved on the basis of an existing tractor with a rotary tiller and an electric suspension control system. The system can also be used for other relatively high-horsepower tractors or tractors driven by other energy sources.

[0050] Two parallel servo cylinders 11 are hinged on the frame of the tractor. In other embodiments, different numbers of servo cylinders 11 can be set according to the needs of the model size. The tail of the servo cylinder 11 is hinged to the frame, and the output shaft of the servo cylinder 11 is respectively hinged to the ball head of the lifting arm 5 on both sides of the frame near the midpoint. The two ends of the lifting arm 5 are respectively hinged to the frame and the lifting rod 6 of the tractor. The other end of the lifting rod 6 is hinged to the lower rod 9. One end of the lower rod 9 is hinged to the frame of the tractor, and the other end is hinged to the three-point suspension of the tractor, wherein the other end of the lower rod 9 is hinged to one of the vertices at the bottom of the three-point suspension, and the vertex at the top of the three-point suspension is hinged to the frame. The bottom edge of the three-point suspension is connected to the rotary tiller 8 near the midpoint through a universal joint.

[0051] The rotary tiller 8 is connected to the tractor via a three-point suspension. In the present embodiment, the rotary tiller is a small rotary tiller, so the tractor used in conjunction with the rotary tiller is a small horsepower tractor.

[0052] Angular displacement sensors 4 are provided at the hinges between the lifting arm 5 and the frame, the hinges between the lower pull rod 9 and the frame, and the hinges between the tail of the servo electric cylinder 11 and the frame. The angular displacement sensor 4 at the hinge between the lifting arm 5 and the frame is used to measure the angular displacement of the lifting arm 5; the angular displacement sensor 4 at the hinge between the lower pull rod 9 and the frame is used to measure the angular displacement of the lower pull rod 9; the angular displacement sensor 4 at the hinge between the servo electric cylinder 11 and the frame is used to measure the angle of the servo electric cylinder 11 relative to the horizontal plane.

[0053] An inclination sensor 7 is provided on the universal joint to measure the inclination of the universal joint. When the rotary tiller 8 is lowered to the required tilling depth, it is measured whether the universal joint angle is greater than 10°. If so, the whole machine controller 2 of the tractor adjusts the height of the rotary tiller through the servo electric cylinder 11 to make the universal joint angle less than 10°, and then starts tilling; when the rotary tiller turns at the end of the field and stops tilling and needs to increase the height of the rotary tiller, it is measured whether the universal joint angle is greater than 30°. If so, the telescopic stroke of the servo electric cylinder 11 is limited or the power of the universal joint is cut off to avoid damage to the universal joint. The whole machine controller 2 prevents the inclination of the universal joint from exceeding the limit value by limiting the telescopic stroke of the servo electric cylinder 11 through the signal transmitted by the inclination sensor 7.

[0054] A pin-type force sensor 10 is installed at the pin hole where the lower pull rod 9 is connected to the frame, which is used to measure the soil resistance of the rotary tiller 8 in real time during operation, and then the whole machine controller 2 calculates the tillage depth of the rotary tiller according to the resistance. The measuring surface of the pin-type force sensor 10 is always on the same horizontal plane as the force surface of the lower pull rod 9.

[0055] A control panel 1 is provided on the tractor, and the control panel 1 is in communication connection with a whole machine controller 2, and an expected tillage depth can be set through the control panel 1.

[0056] The whole machine controller 2 is connected in communication with the angular displacement sensor 4, the inclination sensor 7, the pin force sensor 10, and the servo electric cylinder controller, and the servo electric cylinder controller is connected in communication with the servo electric cylinder. The whole machine controller 2 calculates the current tillage depth through the signals transmitted by the sensors and the servo electric cylinder 11, and controls the telescopic movement of the servo electric cylinder 11 to drive the lifting arm 5, the lifting rod 6, and the lower rod 9 to adjust the tillage depth of the rotary tiller 8. The whole machine controller 2 is also connected in communication with the rotary tiller 8 to control the operation of the rotary tiller.

[0057] A fuel cell 15 and a fuel cell controller 16 are provided on the tractor, and the fuel cell 15 provides power for the tractor and the rotary tiller 8 .

[0058] The tractor is also provided with a power battery 13 and a power battery controller 14. When the fuel cell 15 cannot meet the power requirements of the tractor and the rotary tiller 8, the power battery 13 and the fuel cell 15 together provide power for the tractor and the rotary tiller.

[0059] The whole machine controller 2 is in communication connection with the fuel cell controller 16 and the power battery controller 14 , and is used to control the operation of the fuel cell 15 and the power battery 13 .

[0060] The tractor is driven by a corresponding drive motor, and the drive motor controller is electrically connected to the drive motor. The whole machine controller 2 is communicatively connected to the drive motor controller for controlling the operation of the drive motor.

[0061] The fuel cell 15 and the power battery 13 are electrically connected to the corresponding DC / DC converter 12. The DC / DC converter 12 adjusts the voltage output by the fuel cell 15 and the power battery 13 and outputs it to the high-voltage distribution box 3. The high-voltage distribution box 3 supplies power to various electrical equipment of the tractor (including the servo electric cylinder 11, the rotary tiller, and the drive motor). The high-voltage distribution box 3 can also reasonably distribute the power to the whole machine controller 2, the angular displacement sensor 4, the inclination sensor 7, and the shaft pin force sensor 10.

[0062] An embodiment of a control method for an electric suspension control system of a low-horsepower fuel cell tractor used in conjunction with a rotary tiller, the specific steps are as follows:

[0063] S1. Before the rotary tillage operation starts, the low-horsepower fuel cell tractor sets the preset tillage depth value h of the rotary tiller 8 through the control panel 1. The whole machine controller 2 receives the tillage depth signal output by the control panel 1, and controls the servo electric cylinder 11 and the rotary tiller 8 to move, and adjusts the rotary tiller 8 to the position corresponding to the tillage depth h.

[0064] S2, start the low-horsepower fuel cell tractor to move forward. During this process, the pin-type force sensor 10 measures the soil resistance of the rotary tiller 8 during operation, the inclination sensor 7 set on the universal joint measures the angle of the universal joint, and the angular displacement sensor 4 measures the angular displacement of the lifting arm 5, the lower pull rod 9, and the servo electric cylinder 11. The angular displacement sensor 4, the inclination sensor 7, and the pin-type force sensor 10 transmit the measured data to the whole machine controller 2;

[0065] S3, the whole machine controller 2 calculates the force tillage depth H1 according to the soil resistance measured by the pin-type force sensor 10, converts the position tillage depth H2 according to the telescopic stroke of the servo electric cylinder 11, and adjusts the comprehensive proportional coefficient by the PID controller I, thereby obtaining the comprehensive tillage depth H measured by the force-position comprehensive adjustment through weight calculation, and the PID controller II compares the comprehensive tillage depth H with the preset tillage depth h and calculates the tillage depth control variable value, controls the telescopic action of the servo electric cylinder 11, and thereby adjusts the tillage depth of the rotary tiller 8 in real time;

[0066] S4, the whole machine controller 2 receives the signal transmitted by the inclination sensor 7 installed on the universal joint of the rotary tiller. When the low-horsepower fuel cell tractor is in the turning and stopping tillage working conditions, the whole machine controller 2 limits the telescopic stroke of the servo electric cylinder 11 according to the received signal transmitted by the inclination sensor 7 to control the height of the rotary tiller 8;

[0067] S5, repeat S2 and S3 until the rotary tillage operation is completed.

[0068] The relationship between the tillage depth H1 and soil resistance can be obtained from the following formula:

[0069]

[0070] When the electric suspension of the tractor drives the rotary tiller 8 to work, the operation model of the electric suspension is as follows: Figure 3 shown.

[0071] The relationship between the telescopic stroke S of the servo electric cylinder 11 and the tilling depth H2 of the rotary tiller 8 determined according to the electric suspension operation model is as follows:

[0072]

[0073] In formula (1) and (2),

[0074] H1 is the force tillage depth calculated based on the soil resistance measured by the pin-type force sensor 10;

[0075] F is soil resistance, measured by the pin-type force sensor 10;

[0076] k1 is the soil specific resistance, which can be determined according to different working environments;

[0077] b is the tillage width, which is obtained from the rotary tiller parameters and actual tillage conditions;

[0078] H2 is the tilling depth obtained by converting the telescopic stroke of the servo electric cylinder 11;

[0079] h1 is the vertical distance from the hinge point between the rotary tiller 8 and the tractor to the horizontal plane where the lowest working point of the rotary tiller blade of the rotary tiller is located, which is a fixed value;

[0080] h2 is the vertical distance from the hinge point between the lower pull rod 9 and the frame to the ground, which is a fixed value;

[0081] k2 is the length of the lower pull rod 9 ( Figure 3 The length of CD) and the length from the hinge position of the servo electric cylinder 11 on the lifting arm 5 to the hinge position of the frame ( Figure 3 The ratio of the length of OF in is a fixed value;

[0082] S is the telescopic stroke of the servo electric cylinder 11;

[0083] α DN is the angle between the lower pull rod 9 and the horizontal plane;

[0084] α PQ is the angle between the servo electric cylinder 11 and the horizontal plane;

[0085] α OM is the angle between the lifting arm 5 and the horizontal plane.

[0086] The comprehensive tillage depth H is obtained from the force-position comprehensive adjustment mode:

[0087] H=aH1+(1-a)H2 (3)

[0088] In formula (3),

[0089] a is the comprehensive proportional coefficient, which is adjusted in real time by the PID controller I according to the soil resistance, and its value is 0≤a≤1.

[0090] It can be known from formula (1) that the force plowing depth H1 under resistance adjustment can be obtained by calculating the force measured by the pin-type force sensor 10.

[0091] From formula (2), it can be seen that the tillage depth of the rotary tiller 8 is controlled by the telescopic movement of the servo electric cylinder 11 driving the lifting arm 5, the lifting rod 6, and the lower rod 9. DN , α PQ , α OM The value changes with the telescopic stroke of the servo electric cylinder 11. After being measured by the angular displacement sensor 4, the signal is transmitted to the whole machine controller 2 for calculation to obtain the tilling depth H2 of the rotary tiller 8. That is, the height of the rotary tiller 8 is indirectly controlled by controlling the telescopic stroke of the servo electric cylinder 11.

[0092] It can be seen from formula (3) that the force tillage depth H1 converted from the pin-type force sensor 10 and the position tillage depth H2 converted from the telescopic stroke of the servo electric cylinder 11 are calculated after specific weighting to obtain the comprehensive tillage depth H.

[0093] The present invention designs a resistance-type automatic adjustment comprehensive proportional coefficient based on the relationship between soil resistance F and the comprehensive proportional coefficient. The relationship between the comprehensive proportional coefficient and the soil resistance F is that the soil resistance F is inversely correlated with the comprehensive proportional coefficient. In this embodiment, when the soil resistance F increases or decreases by 3KN, the comprehensive proportional coefficient decreases or increases by 0.1. This relationship can be set according to the actual soil resistance k1 of the tillage. The PID controller I collects the soil resistance F obtained by the transmission signal of the pin-type force sensor 10, and obtains the optimal comprehensive proportional coefficient value under the current rotary tillage conditions based on the relationship between the comprehensive proportional coefficient and the soil resistance, and compares it with the actual comprehensive proportional coefficient in real time and adjusts it to the optimal comprehensive proportional coefficient value.

[0094] The present invention adopts a PID tillage depth controller (i.e., PID controller) of an electric suspension based on PID regulation. The PID controller II compares the actual comprehensive tillage depth H of the rotary tiller obtained by the force-position comprehensive adjustment mode with the preset tillage depth value h, obtains the tillage depth control variable value after processing the error value, and outputs it to the control servo electric cylinder 11, so that the actual comprehensive tillage depth H approaches the preset tillage depth value h.

[0095] The mathematical model of the PID controller is shown in formula (4).

[0096]

[0097] In formula (4),

[0098] u(t) is the control signal of the PID controller regulating the system;

[0099] K p is the proportionality coefficient;

[0100] T i is the integration time constant;

[0101] T d is the differential time constant;

[0102] The transfer function of the PID tillage depth controller of the electric suspension is shown in formula (5).

[0103]

[0104] The working process and principle of the electric suspension control system and control method of a small horsepower fuel cell tractor used in conjunction with a rotary tiller of the present invention are summarized as follows: before the rotary tiller 8 is tilled, the user inputs the set fixed parameters and tillage depth value through the control panel 1 after comprehensive consideration of the tillage environment, soil conditions, etc. The control panel 1 transmits the signal to the whole machine controller 2, and after being processed by the whole machine controller 2, the signal is output to the servo electric cylinder 11, and the servo electric cylinder 11 performs telescopic movement, drives the lifting arm 5 and the lifting rod 6 to move, and then drives the lower rod 9 to realize the rise or fall of the rotary tiller 8. During the tillage process, the whole machine controller 2 calculates the force tillage depth H1 obtained by the data measured by the force sensor 10 and the position tillage depth H2 calculated by the angular displacement sensor 4 and the telescopic stroke of the servo electric cylinder 11, and calculates the comprehensive tillage depth H after the PID controller I adjusts the comprehensive proportional coefficient. The PID controller II compares the obtained comprehensive tillage depth H with the set tillage depth value h, processes to obtain a new output signal, and controls the telescopic stroke of the servo electric cylinder 11 through the output signal. By forming a closed-loop feedback through comprehensive force-position regulation and PID controller, the servo electric cylinder 11 and the comprehensive proportional coefficient are adjusted in real time to reduce the difference between the actual tillage depth and the set tillage depth, thereby achieving a uniform tillage depth of the rotary tiller. When the rotary tiller needs to be raised due to conditions such as turning or stopping tillage, the whole machine controller 2 obtains a signal from the inclination sensor 7 installed on the universal joint of the rotary tiller. If the inclination angle of the universal joint is greater than 30°, the whole machine controller 2 limits the extension and retraction stroke of the servo electric cylinder 11 or cuts off the power of the universal joint.

[0105] In other embodiments of the present invention, a corresponding force sensor may be selected according to the corresponding connection structure between the lower pull rod 9 and the frame, and is not limited to the pin-type force sensor 10 .

[0106] The above shows and describes the main features, basic principles and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention can also be changed and improved according to the actual application situation, and these changes and improvements fall within the scope of the present invention, and the scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An electric suspension system for a tractor used in conjunction with a rotary tiller, characterized in that: The invention comprises a servo electric cylinder (11) hinged on a tractor frame, a lifting arm (5) hinged on an output shaft of the servo electric cylinder (11), a lifting rod (6) hinged on the lifting arm (5), a lower rod (9) hinged on the lifting rod (6), a three-point suspension hinged on the lower rod (9), and a rotary tiller (8) connected to the three-point suspension via a universal joint, wherein the lifting arm (5) is hinged on the tractor frame, the hinge point between the output shaft of the servo electric cylinder (11) and the lifting arm (5) is located between the hinge points of the lifting arm (5) and the tractor frame and the lifting rod (6), the lower rod (9) is hinged on the tractor frame, the three-point suspension is hinged on the tractor frame, and the hinge point between the lifting rod (6) and the lower rod (9) is located between the lower rod (9) and the tractor frame and the hinge points of the three-point suspension; Angular displacement sensors (4) are arranged at the hinged positions of the servo electric cylinder (11), the lifting arm (5), the lower pull rod (9) and the tractor frame, a force sensor is also arranged at the hinged position of the lower pull rod (9) and the tractor frame, and an inclination sensor (7) is arranged on the universal joint. The angular displacement sensor (4), the force sensor, the inclination sensor, the servo electric cylinder (11) are communicatively connected with the whole machine controller (2), and the whole machine controller (2) is communicatively connected with the control panel (1).

2. The electric suspension system of a tractor matched with a rotary tiller according to claim 1, characterized in that: It also includes a fuel cell (15) and a fuel cell controller (16) for supplying power to a tractor, a rotary tiller (8), a servo electric cylinder (11), an angular displacement sensor (4), a force sensor, and an inclination sensor (7); the fuel cell controller (16) is communicatively connected to the whole machine controller (2).

3. The electric suspension system of a tractor matched with a rotary tiller according to claim 2, characterized in that: It also includes a power battery (13) and a power battery controller (14) for supplementing power supply, and the power battery controller (14) is communicatively connected with the whole machine controller (2).

4. The electric suspension system of a tractor matched with a rotary tiller according to claim 3, characterized in that: The fuel cell (15) and the power battery (13) are electrically connected to the corresponding DC / DC converter (12), the DC / DC converter (12) is electrically connected to the high-voltage distribution box (3), and the high-voltage distribution box (3) is electrically connected to the tractor, the rotary tiller (8), the servo electric cylinder (11), the angular displacement sensor (4), the force sensor, and the inclination sensor (7).

5. The electric suspension system of a tractor matched with a rotary tiller according to claim 1, characterized in that: The force sensor is a shaft pin type force sensor (10), and the shaft pin type force sensor (10) is installed at the shaft pin hole where the lower pull rod (9) is hinged to the frame.

6. The electric suspension system of a tractor matched with a rotary tiller according to claim 1 or 5, characterized in that: The measuring surface of the force sensor (10) and the force-bearing surface of the lower pull rod (9) are on the same horizontal plane.

7. A control method for an electric suspension system of a tractor matched with a rotary tiller, characterized in that: The following steps are involved: S1. Before the tractor starts the rotary tillage operation, the tractor sets the preset tillage depth value h for the rotary tiller operation through the control panel (1), and the whole machine controller (2) receives the signal output by the control panel (1); S2, start the tractor to move forward. During this process, the force sensor measures the soil resistance of the rotary tiller during operation, the inclination sensor (7) measures the angle of the universal joint, and the angular displacement sensor (4) measures the angular displacement of the lifting arm (5), the lower pull rod (9), and the servo electric cylinder (11), and the measured data is input into the whole machine controller (2); S3, the whole machine controller (2) calculates the force tillage depth H1 according to the soil resistance measured by the force sensor, converts the position tillage depth H2 according to the telescopic stroke of the servo electric cylinder (11), adjusts the comprehensive proportional coefficient by the PID controller I, and obtains the comprehensive tillage depth H measured by the force and position comprehensive adjustment through weight calculation, calculates the tillage depth control variable value by the PID controller II, controls the telescopic action of the servo electric cylinder (11), and adjusts the tillage depth of the rotary tiller (8) in real time. S4, when the tractor is in a turning or stopped tillage working condition, the whole machine controller (2) receives the signal transmitted by the tilt sensor (7), controls the height of the rotary tiller (8), and limits the telescopic stroke of the servo electric cylinder (11). S5, repeat S2 and S3 until the rotary tillage operation is completed.

8. The control method of the electric suspension system of a tractor matched with a rotary tiller according to claim 7, further characterized by: The relationship between the tillage depth H1 and soil resistance is obtained by the following formula: In formula (1), F is the soil resistance, measured by the force sensor; k1 is the soil specific resistance, which can be determined according to different working environments; b is the tillage width, which is obtained from the rotary tiller parameters and actual tillage conditions.

9. The control method of the electric suspension system of a tractor matched with a rotary tiller according to claim 7, characterized in that: The relationship between the telescopic stroke of the servo electric cylinder (11) and the tilling depth H of the rotary tiller (8) determined according to the electric suspension operation model is as follows: In formula (2), h1 is the vertical distance from the hinge point between the rotary tiller and the tractor to the horizontal plane of the lowest working point of the rotary tiller's rotary blade, which is a fixed value; h2 is the vertical distance from the hinge point between the lower tie rod and the frame to the ground, which is a fixed value; k1 is the ratio of the length of the lower pull rod to the length from the hinge position of the servo electric cylinder on the lifting arm to the hinge position of the frame, which is a fixed value; S is the telescopic stroke of the servo cylinder; α DN is the angle between the pull-down rod and the horizontal plane; α PQ is the angle between the servo electric cylinder and the horizontal plane; α OM It is the angle between the lifting arm and the horizontal plane.

10. The control method of the electric suspension system of a tractor matched with a rotary tiller according to claim 7, further characterized by: The comprehensive tillage depth H is obtained from the force-position comprehensive adjustment mode: H=aH1+(1-a)H2 (3) In formula (3), a is the comprehensive proportional coefficient, which is adjusted in real time by the PID controller according to soil resistance, and its value is 0≤a≤1.

Images