CN105711581A - Stepless speed change tractor control system and control method thereof - Google Patents
Stepless speed change tractor control system and control method thereof Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W10/00—Conjoint control of vehicle sub-units of different type or different function
- B60W10/04—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units
- B60W10/06—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units including control of combustion engines
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W10/00—Conjoint control of vehicle sub-units of different type or different function
- B60W10/10—Conjoint control of vehicle sub-units of different type or different function including control of change-speed gearings
- B60W10/101—Infinitely variable gearings
- B60W10/103—Infinitely variable gearings of fluid type
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
- B60W30/18—Propelling the vehicle
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
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- Mechanical Engineering (AREA)
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Abstract
The invention provides a stepless speed change tractor control system and a control method thereof. The control system comprises an engine, a hydraulic mechanical stepless speed changer, a vehicle speed sensor, a traction force sensor, an engine electronic control unit, a speed changer electronic control unit, and a speed changer hydraulic control unit. The stepless speed change tractor control system adopts NT/gT to characterize traction production efficiency-economical efficiency comprehensive optimum at maximum; an optimal speed changing ratio and an engine rotary speed, which meet the traction production efficiency-economical efficiency comprehensive optimum, are calculated through optimizing the speed changing ratio of the speed changer, so that the tractor has good fuel oil economical efficiency under the condition that the relatively large production rate is obtained.
Description
Technical Field
The invention relates to a tractor control system, in particular to a stepless speed change tractor control system and a control method thereof.
Background
The tractor is as the important instrument of farmland operation, and complicated operational environment makes the traction load of tractor and the speed of a motor vehicle undulant great, and hydraulic machinery buncher can adapt to complicated operating mode, makes the vehicle performance obtain very big promotion. Generally, the operation modes of the continuously variable tractor are classified into a productivity maximizing operation mode in which the tractor fuel economy is poor and an economy optimizing operation mode; in the best economy mode, the tractor operates at the lowest point of fuel consumption, which can easily cause engine stall if vehicle traction load is suddenly increased.
Currently, in order to achieve greater productivity while ensuring the economy of the tractor, weighting factors are introduced into the tractor control method. For example, huo will be granted, sun winter will be given in the "overall optimization control strategy for continuously variable transmission system" document: and a proper weight coefficient is selected through the judgment of a driver, so that the overall optimum of the vehicle transmission system under a certain condition is obtained. However, in actual operation, the proficiency level of the operation of each driver and the judgment of the complex road condition are different, and good effects cannot be obtained.
Disclosure of Invention
The invention provides a control system of a continuously variable tractor and a control method thereof, aiming at overcoming the problem that the prior art method is difficult to well solve the contradiction between the economy and the productivity of the tractor, and ensuring that the tractor still has good fuel economy on the premise of obtaining higher productivity.
The technical scheme adopted by the invention for solving the problems is as follows: a stepless speed change tractor control system comprises an engine, a hydraulic mechanical stepless speed changer, a vehicle speed sensor, a traction force sensor, an engine electronic control unit, a speed changer electronic control unit and a speed changer hydraulic control unit, wherein the hydraulic mechanical stepless speed changer comprises a mechanical speed change mechanism, a hydraulic speed regulation mechanism and a planetary gear mechanism which combines mechanical power and hydraulic power, the hydraulic speed regulation mechanism is a closed hydraulic speed regulation mechanism consisting of an electro-hydraulic proportional variable pump and a quantitative motor, and the electro-hydraulic proportional variable pump comprises an electro-hydraulic proportional electromagnetic valve, an oil cylinder plunger and a swash plate; the output ends of the traction force sensor and the vehicle speed sensor are connected with the input end of a transmission electronic control unit, the output end of the transmission electronic control unit is connected with the input ends of an engine electronic control unit and a transmission hydraulic control unit, the transmission hydraulic control unit outputs a control signal of a tilting angle of a tilting tray according to the optimal gear ratio, an electro-hydraulic proportional solenoid valve receives the control signal, and after passing through an amplifier, the electro-hydraulic proportional solenoid valve controls a cylinder plunger to move, pushes the tilting tray to deflect, changes the displacement ratio of a variable pump, and realizes stepless speed change.
The invention discloses a control method of a control system of a continuously variable tractor, which comprises the following steps:
step one, respectively converting the input rotating speed of an engineThe range is 1300-2300 r/min, and the input torque of the engineSet to 0 to 1200N · m, wherein the transmission ratio of the transmission of formula (1)，，Is the input angular speed of the engine, in rad/s,is the output angular velocity of the variator, in rad/s;is the output torque of the transmission, in units of N · m; setting tractive effort of a tractorIn the range of 0.01 to 80kN, in increments of each step=1kN；
Step two, respectively measuring the running speed and the traction resistance of the tractor by using a vehicle speed sensor and a force sensor according to the formula (2)And formula (3)Separately determining the output angular velocity of the variatorAnd output torqueWherein the slip rate(ii) a Rolling friction forceThe unit is N, wherein,in order to obtain the coefficient of friction,= 0.05-0.75, m is the total weight of the tractor, and the unit is kg;the unit is the running speed of the tractor and is m/s;is the radius of the driving wheel of the tractor, and the unit is m;is the main transmission ratio of the tractor;；(ii) a Setting up= 0.01-40 km/h, increment per step；
Step three, utilizing the output rotating speed of the transmission obtained in the step twoAnd output torqueIf, ifThen carrying out the next step; otherwise, the optimum gear ratioAfter storing the optimal gear ratio, returning to the step two to recalculate by using the increment set by the optimized calculation; wherein,is the rated torque of the engine and has the unit of N.m;is the maximum output power of the engine, and the unit is W;
step four, changing the gear ratio of the transmissionSet to 0.01 to 2.24, increments per stepFrom the set transmission ratio, using equation (1)And the output speed of the transmissionCalculatingAnd make a judgment onWhether the requirement of 1300 is less than or equal to is met2300, if so, carrying out the next step; otherwise, according to the increment per stepRe-selection of gear ratio；
(1) IfWhen the circulation is finished, the increment set according to the step two is addedReselect toOtherwise, returning to the third step;
(2) ifWhen the cycle is finished, the increase is set according to the step oneMeasurement of=1 reselectionOtherwise, returning to the step two;
(3) ifWhen the circulation is finished, all the steps are finished, otherwise, the step one is returned;
step five, utilizing a formula (4)Calculated according to step fourDetermining the limit torque corresponding to the engineAnd setting the increment per step(ii) a Using the formula (5)And formula (6)Calculating specific fuel consumption of tractorWhereinin order to achieve the fuel consumption rate of the engine,，the transmission efficiency of the speed changer is improved;；(ii) a Using formula (7)Calculating tractor traction powerThe unit is W; judgment ofWhether or not it is the largest, ifAt the maximum, the corresponding gear ratio is the optimum gear ratio; otherwise, returning to the step four.
The invention utilizes the traction power of the tractor () Maximum characteristic maximum productivity, using specific fuel consumption of the tractor) The minimum characteristic economy is optimal, the comprehensive optimization of productivity and economy is taken as a control target, andthe maximum characteristic tractor productivity-economy is combined to be optimal. Under any traction load and speed, the tractor is guaranteedAnd the method is the basic requirement for realizing the best comprehensive tractor productivity-economy. When the tractor works under the comprehensive optimal conditions of productivity and economy and the traction load changes, the tractor can stably run according to the set target speed to meet the working requirement so as to ensure the working quality.
The speed change rule established by the invention is that in a load characteristic field, according to the running speed and traction load of the tractor, the working point of the transmission is determined in a transmission output characteristic field, and the working rotating speed of the engine is determined according to the optimal speed change ratio.
The tractor is driven at any speed and traction load corresponding to a rotating speed and torque in the output characteristic field of the transmission. By continuously adjusting the transmission gear ratio, an infinite number of engine speeds and torques can be obtained corresponding thereto. By means of optimization calculation, find outThe maximum corresponding transmission ratio is the optimal ratio. The engine operating speed can be determined from the transmission speed and the optimum gear ratio.
Has the advantages that: the invention adopts a binary regulation modeThe maximum characteristic tractor productivity-economy is comprehensively optimal; tractor meeting requirements through optimized calculation of transmission gear ratioOptimum gear ratio and engine speed for productivity-economy integration; the speed, the traction resistance, the optimal speed ratio and the engine speed are used as control parameters, the speed change electronic control unit determines the optimal speed ratio and the engine speed according to the speed and the traction load, and the engine speed and the transmission speed ratio are adjusted through the engine electronic control unit and the transmission hydraulic control unit, so that the productivity-economy of the tractor is comprehensively optimal, the tractor is ensured to have better traction performance, fuel economy and driving comfort, and the automatic operation level of the tractor is improved.
Drawings
FIG. 1 is a flow chart of a control method of the variable speed control system of the infinitely variable speed tractor according to the present invention;
FIG. 2 is a schematic diagram of the engine and transmission cooperative control in the case of the comprehensive optimal shift of the productivity-economy of the infinitely variable speed tractor;
FIG. 3 is a schematic diagram of a comprehensive optimal control system for productivity-economy of a continuously variable tractor;
FIG. 4 is a control schematic diagram of the engine, variable pump and constant motor hydraulic speed-regulating mechanism when the productivity-economy combination of the infinitely variable speed tractor is optimal.
Reference numerals: in the attached figure 4, the device comprises an electro-hydraulic proportional solenoid valve 1, an oil cylinder plunger 2, an overflow valve 3, a high-pressure overflow valve 4, a pressure stabilizing overflow valve 5, a filter 6, a filter 7 and an oil tank.
Detailed Description
The present invention is further described with reference to specific examples to enable those skilled in the art to better understand the present invention and to practice the same, but the examples are not intended to limit the present invention.
A continuously variable tractor control system comprises an engine, a hydraulic mechanical continuously variable transmission, a vehicle speed sensor, a traction force sensor, an engine electronic control unit, a transmission electronic control unit and a transmission hydraulic control unit, wherein the hydraulic mechanical continuously variable transmission comprises a mechanical speed change mechanism, a hydraulic speed regulation mechanism and a planetary gear mechanism which combines mechanical power and hydraulic power, the hydraulic speed regulation mechanism is a closed hydraulic speed regulation mechanism which consists of an electro-hydraulic proportional variable pump and a quantitative motor, and the electro-hydraulic proportional variable pump comprises an electro-hydraulic proportional solenoid valve, an oil cylinder plunger and a swash plate. The output ends of the traction force sensor and the vehicle speed sensor are connected with the input end of a transmission electronic control unit, the output end of the transmission electronic control unit is connected with the input ends of an engine electronic control unit and a transmission hydraulic control unit, the transmission hydraulic control unit outputs a control signal of a tilting angle of a tilting tray according to the optimal gear ratio, an electro-hydraulic proportional solenoid valve receives the control signal, and after passing through an amplifier, the electro-hydraulic proportional solenoid valve controls a cylinder plunger to move, pushes the tilting tray to deflect, changes the displacement ratio of a variable pump, and realizes stepless speed change.
The electronic control unit of the transmission comprises a central processing module, a signal input module, a signal output module, a communication module and an emergency processing module, wherein the central processing module comprises a power module, a reset module, a clock module and a JTAG interface; the signal input module is used for inputting information reflecting the intention of a driver and the state of the whole system to the central processing module; the signal output module is used for driving an electromagnetic valve of a transmission hydraulic control unit to realize transmission speed change; the communication module comprises a CAN communication module, an SCI communication module and an SPI display module.
A control method of a control system of a continuously variable tractor comprises the following steps: step one, respectively converting the input rotating speed of an engineThe range is 1300-2300 r/min, and the input torque of the engineSet to 0 to 1200N · m, wherein the transmission ratio of the transmission of formula (1)，，Is the input angular speed of the engine, in rad/s,is the output angular velocity of the variator, in rad/s;is the output torque of the transmission, in units of N · m; setting tractive effort of a tractorIn the range of 0.01 to 80kN, in increments of each step=1kN；
Step two, respectively measuring the running speed and the traction resistance of the tractor by using a vehicle speed sensor and a force sensor according to the formula (2)And formula (3)Separately determining the output angular velocity of the variatorAnd output torqueWherein the slip rate(ii) a Rolling friction forceThe unit is N, wherein,in order to obtain the coefficient of friction,= 0.05-0.75, m is the total weight of the tractor, and the unit is kg;the unit is the running speed of the tractor and is m/s;is the radius of the driving wheel of the tractor, and the unit is m;is the main transmission ratio of the tractor;；(ii) a Setting up= 0.01-40 km/h, increment per step；
Step three, utilizing the output rotating speed of the transmission obtained in the step twoAnd output torqueIf, ifThen carrying out the next step; otherwise, the optimum gear ratioAfter storing the optimal gear ratio, returning to the step two to recalculate by using the increment set by the optimized calculation; wherein,is the rated torque of the engine and has the unit of N.m;is the maximum output power of the engine, and the unit is W;
step four, changing the gear ratio of the transmissionSet to 0.01 to 2.24, increments per stepFrom the set transmission ratio, using equation (1)And the output speed of the transmissionCalculatingAnd make a judgment onWhether the requirement of 1300 is less than or equal to is met2300, if so, carrying out the next step; otherwise, according to the increment per stepRe-selection of gear ratio；
(1) IfWhen the circulation is finished, the increment set according to the step two is addedReselect toOtherwise, returning to the third step;
(2) ifWhen the circulation is finished, the increment set according to the step one is added=1 reselectionOtherwise, returning to the step two;
(3) ifWhen the circulation is finished, all the steps are finished, otherwise, the step one is returned;
step five, utilizing a formula (4)Calculated according to step fourDetermining the limit torque corresponding to the engineAnd setting the increment per step(ii) a Using the formula (5)And formula (6)Calculating specific fuel consumption of tractorWhereinin order to achieve the fuel consumption rate of the engine,，the transmission efficiency of the speed changer is improved;；(ii) a Using formula (7)Calculating tractor traction powerThe unit is W; judgment ofWhether or not it is the largest, ifAt the maximum, the corresponding gear ratio is the optimum gear ratio; otherwise, returning to the step four.
The TMS320C24X type DSP microcontroller is adopted in the invention, and the main interface signals are as follows: the input signals comprise analog signals of vehicle forward, reverse, gear switch, rack displacement, traction resistance, running speed, clutch pressure and the like. And outputting a clutch electromagnetic directional valve switch control signal, a variable pump control proportional electromagnetic valve control signal and an engine instruction rotating speed signal. The man-machine interface displays the values of the vehicle speed, the gear ratio, the engine speed, the displacement ratio and the like.
The DSP is internally provided with a microprocessor, a program and data Flash memory, an RAM, a PWM control circuit, an A/D and a D/A, a parallel I/O interface, a CAN interface and the like. The photoelectric isolation circuit can protect the microcontroller and improve the anti-jamming capability of the TCU, the signal conditioning circuit amplifies and filters an analog signal to ensure reliable sampling input, the power amplification circuit amplifies the power of the signal to reach a required value, and short-circuit and back-voltage protection is carried out on a power element. The emergency circuit is used for forcing the transmission to advance at a low speed or combine a clutch of a reversing section through an external switch circuit when the transmission cannot work normally, so that power of an engine can be transmitted to a driving wheel of the tractor through the transmission, and a driver is guaranteed to transfer the tractor to a maintenance station from a fault point.
The engine adopts electronic speed regulation, the electronic speed regulator receives the engine instruction rotational speed, outputs the rack displacement drive signal, controls the displacement of the oil pump rack, adjusts the oil supply, and then changes the engine rotational speed, guarantees that the actual rotational speed of the engine is consistent with the instruction rotational speed, and the speed regulator measures the engine rotational speed and the rack displacement in real time, and controls the rack displacement and the rotational speed in a closed loop mode.
The process of solving the optimal gear ratio of the transmission and the engine speed by the traction load and the vehicle speed is reverse solution, the efficiency calculation of a Hydraulic Mechanical Continuously Variable Transmission (HMCVT) is complex, and the optimal gear ratio obtained by optimization calculation is stored in a memory unit in a form of a table to improve the calculation efficiency; the slip rate is used as an important factor influencing the vehicle performance, and the slip rate and driving force relation under different road conditions is fitted according to the experimental data of the tractors on different roads under the standard working condition, so that the requirements under the non-standard working condition are met through correction.
The invention provides an engineering application of comprehensive optimal stepless speed change law by using a target speed, traction resistance, an optimal speed change ratio and an engine rotating speed as control parameters; the control target is that the tractor runs according to a given speed, the gear ratio and the engine speed are adjusted according to the change of the traction load, the comprehensive best productivity-economy of the tractor is realized, and the control input is the target speed and the traction force; the control output is the optimal transmission ratio of the transmission and the engine speed. A tractor productivity-economy comprehensive optimal speed change control system formulated according to a stepless speed change law comprises: the vehicle speed sensor is used for measuring the running speed of the tractor; the traction sensor is used for measuring the traction resistance of the tractor during working; the electronic control unit of the speed changer, according to speed and traction load, judge the engine load, confirm the optimum speed change ratio of the speed changer and corresponding engine speed; the engine electronic control unit adjusts the engine speed according to the engine speed signal; and the HMCVT hydraulic control unit adjusts the inclination angle of a swash plate of the variable pump according to the gear ratio signal, changes the displacement ratio of the pump and realizes stepless speed change. The speed sensor is installed on the non-driving wheel of the tractor, and the traction force sensor is installed at the joint of the hydraulic suspension mechanism of the tractor and the agricultural implement.
The invention utilizes the electronic control technology to realize the comprehensive optimal stepless speed change and control of the productivity-economy of the hydraulic mechanical stepless speed change tractor. The tractor is made to work under the comprehensive optimal working condition of productivity-economy by monitoring the traction resistance and speed of the tractor and regulating the speed ratio of the speed variator and the rotation speed of the engine.
The specific embodiment is as follows: the invention takes a certain oriental red 400 horsepower wheeled tractor equipped with a hydraulic mechanical stepless speed changer as an object, and the main parameters of the system are as follows: the whole tractor mass m =7760kg, and the tractor main transmission ratio=36.348, transmission gear ratioThe range of 0 to 2.24, the radius r of the tractor driving wheeld=0.9046m, rated engine power Ne0=228kw, maximum output power of the engine=294kW, rated engine speed=2100(r/min), maximum engine speed=2300(r/min), engine maximum torque=1200N · m, maximum traction force=80kN。
As shown in FIG. 1, a method for optimizing and calculating the optimal transmission ratio of a continuously variable tractor in terms of productivity-economy combination comprises the following steps:
(1) setting the limit rotation speed and torque of an engine and the range of the HMCVT (hybrid drive-variable transmission) ratio, wherein the speed of a wheeled tractor in field operation is mainly 0.5-10 km/h, the speed of field and road transportation is mainly 15-30 km/h, the speed range is set to be 0.01-40 km/h in optimization calculation, in order to ensure the normal work of the tractor, the traction load is smaller than the maximum traction force of the tractor, the range of the traction load of the tractor in the optimization calculation is set to be 0.01-80 kN, in order to avoid the phenomenon that the divisor is 0, the range of the HMCVT ratio is set to be 0.01-2.24, and in the optimization=1，，，；
(2) According to the tractor traction load and vehicle speed, the tractor traction power and speed changer output angular speed can be obtainedTorque, torqueIf power ofCorresponding to each gear ratioThe corresponding engine speed can be obtainedIn order to avoid the engine working on the external characteristic, the actual torque should be limited within the external characteristic to ensure that the engine has certain torque reserve, and the limit torque corresponding to the engine is obtained according to the rotating speed of the engineCalculating the efficiency of HMCVT and the fuel consumption rate of the engine according to the rotating speed and the torque of the engine, and if the power is larger than the power，，The engine rated torque.
(3) Judgment ofWhether or not it is the largest, ifIf the speed ratio is not maximum, the next cycle calculation is carried out;
(4) if the output power of the transmission is larger than the maximum power of the engine, the optimal gear ratio is taken as the ratio of the output torque of the transmission and the rated torque of the engine;
(5) the cycle ends when the engine, transmission speed and torque and transmission ratio have all reached limit values.
The optimization variables include transmission gear ratio and engine operating point, and the optimization objective isAnd max. Constraints include engine and transmission speed, torque constraints, transmission ratio constraints and power constraints. The slip rate of the tractor is calculated according to the slip rate characteristic curve, and the slip rate characteristic curves under different road conditions are stored in the memory unit in the form of mathematical expressions.
In order to realize rapid real-time control, the optimally calculated optimal speed ratio of the transmission and the engine speed are stored in a memory unit of the controller in a form of a table, and the corresponding optimal speed ratio of the transmission and the engine speed under any vehicle speed and traction load can be solved by adopting an interpolation algorithm.
As shown in fig. 2, the productivity-economy of the continuously variable tractor integrates the engine and the transmission cooperative control principle during the optimal speed change, the driving force and the transmission torque are obtained by the traction force of the tractor, and the vehicle slip ratio is calculated according to the tractor slip ratio characteristic curve; a tractor theoretical speed and a transmission rotation speed are calculated according to the target speed, an optimal transmission ratio and an engine rotation speed are obtained from an optimal transmission ratio table, and the engine and the transmission ratio are respectively adjusted according to the engine rotation speed and the optimal transmission ratio. And in order to ensure the stability of the vehicle speed, the vehicle speed is subjected to feedback control.
As shown in figure 3, the tractor productivity-economy integrates the optimal speed change rule and the control system principle, signals of a traction force sensor and a vehicle speed sensor are input to a signal processing unit of a speed change ECU, the signals are transmitted to an engine load judging unit and a cooperative control unit after being processed, the engine speed and the optimal speed change ratio of a transmission are calculated and obtained, an engine speed command is input to the engine ECU, the engine speed is controlled and adjusted, the optimal speed change ratio command is input to an HMCVT hydraulic control unit, the inclination angle of a swash plate of the transmission is controlled and adjusted, the displacement ratio of a variable pump is changed, and the stepless speed change is.
As shown in fig. 4, the tractor productivity-economy integrates the principle of an engine, pump-motor control system during optimal speed change control, the engine adopts electronic speed regulation, the electronic speed regulator receives the engine command speed, outputs a rack displacement driving signal, controls the displacement of an oil pump rack, adjusts the oil supply amount, further changes the engine speed, ensures that the actual engine speed is consistent with the command speed, measures the engine speed and the rack displacement in real time, and controls the rack displacement and the engine speed in a closed-loop mode.
In the invention, as shown in figure 4, a variable pump-fixed displacement motor adopts closed transmission, an electro-hydraulic proportional solenoid valve 1 receives an inclination angle electric signal of a transmission swash plate, and controls a cylinder plunger 2 to move after passing through an amplifier, so as to push the swash plate to deflect and change the displacement ratio of the variable pump. The electro-hydraulic proportional solenoid valve 1 realizes closed control through mechanical rigid feedback of the oil cylinder plunger 2, so that the inclination angle of the swash plate is changed in proportion to control current. In order to avoid that the oil line pressure reaches the highest working pressure caused by the over-quick rotation of the swash plate during acceleration and deceleration, the safety valve releases the pressure to the control oil line when the oil pressure of the main oil line exceeds a set value; when the oil pressure of the main oil way exceeds the maximum value, the overflow valve 3 overflows the oil way to protect the safety of a pump-motor system; a small amount of oil on the low-pressure side of the main oil way overflows back to the oil way by the flushing valve, so that the effects of flushing impurities in the oil way and cooling are achieved, and the influence on the performance and leakage of a hydraulic system due to overhigh oil temperature is avoided; the leakage of the pump-motor and the overflow oil of the flushing valve flow into the cooler and return to the oil tank for recycling after cooling. The high-pressure overflow valve 4 is used for protecting the main oil way when the pressure of the main oil way is the maximum pressure value; a pressure stabilizing overflow valve 5 for stabilizing the pressure of the oil from the oil tank 7; the oil entering the oil tank 7 needs to be filtered through the filter 6.
Claims (2)
1. The utility model provides a infinitely variable speed tractor control system, includes engine, hydraulic pressure machinery buncher, speed sensor, traction force sensor, engine electronic control unit, derailleur hydraulic control unit, its characterized in that: the hydraulic mechanical stepless transmission comprises a mechanical speed change mechanism, a hydraulic speed regulation mechanism and a planetary gear mechanism which combines mechanical power and hydraulic power, wherein the hydraulic speed regulation mechanism is a closed hydraulic speed regulation mechanism consisting of an electro-hydraulic proportional variable pump and a quantitative motor, and the electro-hydraulic proportional variable pump comprises an electro-hydraulic proportional electromagnetic valve, an oil cylinder plunger and a swash plate;
the output ends of the traction force sensor and the vehicle speed sensor are connected with the input end of a transmission electronic control unit, the output end of the transmission electronic control unit is connected with the input ends of an engine electronic control unit and a transmission hydraulic control unit, the transmission hydraulic control unit outputs a control signal of a tilting angle of a tilting tray according to the optimal gear ratio, an electro-hydraulic proportional solenoid valve receives the control signal, and after passing through an amplifier, the electro-hydraulic proportional solenoid valve controls a cylinder plunger to move, pushes the tilting tray to deflect, changes the displacement ratio of a variable pump, and realizes stepless speed change.
2. A control method using a continuously variable tractor control system as claimed in claim 1, comprising the steps of:
step one, respectively converting the input rotating speed of an engineThe range is 1300-2300 r/min, and the input torque of the engineSet to 0 to 1200N · m, wherein the transmission ratio of the transmission of formula (1)，，Is the input angular speed of the engine, in rad/s,is the output angular velocity of the variator, in rad/s;is the output torque of the transmission, in units of N · m; setting tractive effort of a tractorIn the range of 0.01 to 80kN, in increments of each step=1kN；
Step two, respectively measuring the running speed and the traction resistance of the tractor by using a vehicle speed sensor and a force sensor according to the formula (2)And formula (3)Separately determining the output angular velocity of the variatorAnd output torqueWherein the slip rate(ii) a Rolling friction forceThe unit is N, wherein,in order to obtain the coefficient of friction,= 0.05-0.75, m is the total weight of the tractor, and the unit is kg;the unit is the running speed of the tractor and is m/s;is the radius of the driving wheel of the tractor, and the unit is m;is the main transmission ratio of the tractor;；(ii) a Setting up= 0.01-40 km/h, increment per step；
Step three, utilizing the output rotating speed of the transmission obtained in the step twoAnd output torqueIf, ifThen carrying out the next step; otherwise, the optimum gear ratioAfter storing the optimal gear ratio, returning to the step two to recalculate by using the increment set by the optimized calculation; wherein,is the rated torque of the engine and has the unit of N.m;is the maximum output power of the engine, and the unit is W;
step four, changing the gear ratio of the transmissionSet to 0.01 to 2.24, increments per stepFrom the set transmission ratio, using equation (1)And the output speed of the transmissionCalculatingAnd make a judgment onWhether the requirement of 1300 is less than or equal to is met2300, if so, carrying out the next step; otherwise, according to the increment per stepRe-selection of gear ratio；
(1) IfWhen the circulation is finished, the increment set according to the step two is addedReselect toOtherwise, returning to the third step;
(2) ifWhen the circulation is finished, the increment set according to the step one is added=1 reselectionOtherwise, returning to the step two;
(3) ifWhen the circulation is finished, all the steps are finished, otherwise, the step one is returned;
step five, utilizing a formula (4)Calculated according to step fourDetermining the limit torque corresponding to the engineAnd setting the increment per step(ii) a Using the formula (5)And formula (6)Calculating specific fuel consumption of tractorWhereinin order to achieve the fuel consumption rate of the engine,，the transmission efficiency of the speed changer is improved;；(ii) a Using formula (7)Calculating tractor traction powerThe unit is W; judgment ofWhether or not it is the largest, ifAt the maximum, the corresponding gear ratio is the optimum gear ratio; otherwise, returning to the step four.
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| CN109185444A (en) * | 2018-10-26 | 2019-01-11 | 合肥工业大学 | A kind of job control method for novel crawler paddy field tractor variable ratio drive system |
| CN110304046A (en) * | 2019-08-01 | 2019-10-08 | 河南科技大学 | A kind of economy control method of stepless speed changing tractor control system |
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| CN113494599A (en) * | 2021-07-06 | 2021-10-12 | 南京农业大学 | High-power tractor HMCVT fault self-diagnosis system |
| CN114251436A (en) * | 2021-12-22 | 2022-03-29 | 潍柴动力股份有限公司 | Oil temperature control method of HMCVT, continuously variable transmission and vehicle |
| CN115217017A (en) * | 2022-07-18 | 2022-10-21 | 潍柴动力股份有限公司 | Speed control method, device and equipment for road roller and storage medium |
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