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CN112594375B - Speed ratio change rate control method for mechanical hydraulic stepless transmission of tractor - Google Patents

Speed ratio change rate control method for mechanical hydraulic stepless transmission of tractor Download PDF

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Publication number
CN112594375B
CN112594375B CN202011509824.3A CN202011509824A CN112594375B CN 112594375 B CN112594375 B CN 112594375B CN 202011509824 A CN202011509824 A CN 202011509824A CN 112594375 B CN112594375 B CN 112594375B
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speed ratio
gear
change rate
expected
rate
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CN112594375A (en
Inventor
赵海东
严鉴铂
刘义
邱辉鹏
王文婷
胡晓承
宋乾斌
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Shaanxi Fast Gear Co Ltd
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Shaanxi Fast Gear Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/02—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used
    • F16H61/0202—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used the signals being electric
    • F16H61/0204—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used the signals being electric for gearshift control, e.g. control functions for performing shifting or generation of shift signal
    • F16H61/0213—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used the signals being electric for gearshift control, e.g. control functions for performing shifting or generation of shift signal characterised by the method for generating shift signals
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
    • F16H59/68—Inputs being a function of gearing status
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
    • F16H59/68—Inputs being a function of gearing status
    • F16H59/70—Inputs being a function of gearing status dependent on the ratio established
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
    • F16H59/68—Inputs being a function of gearing status
    • F16H2059/6807—Status of gear-change operation, e.g. clutch fully engaged
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
    • F16H59/68—Inputs being a function of gearing status
    • F16H2059/6838—Sensing gearing status of hydrostatic transmissions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/02—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used
    • F16H61/0202—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used the signals being electric
    • F16H61/0204—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used the signals being electric for gearshift control, e.g. control functions for performing shifting or generation of shift signal
    • F16H61/0213—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used the signals being electric for gearshift control, e.g. control functions for performing shifting or generation of shift signal characterised by the method for generating shift signals
    • F16H2061/0216—Calculation or estimation of post shift values for different gear ratios, e.g. by using engine performance tables

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Transmission Device (AREA)

Abstract

The invention provides a speed ratio change rate control method for a mechanical hydraulic stepless speed changer of a tractor, and solves the problem that the smoothness of the whole tractor is difficult to ensure in the prior art. The control method comprises the following steps: calculating an expected speed ratio and an expected speed ratio change rate according to a signal currently acquired by the vehicle; judging the current gear operation condition, and performing expected speed ratio change rate control in the adjacent gear switching process or expected speed ratio change rate control in the gear reversing shuttle process; in conjunction with transmission shift enable control, either the rate of change of the desired input speed ratio or the maximum rate of change of the desired shuttle speed ratio is selected as the rate of change output of the desired output speed ratio.

Description

Speed ratio change rate control method for mechanical hydraulic stepless transmission of tractor
Technical Field
The invention relates to a speed ratio change rate control method of a mechanical hydraulic stepless speed changer, in particular to a speed ratio change rate control method of a mechanical hydraulic stepless speed changer of a high-horsepower tractor.
Background
The high-horsepower tractor can realize that a driver can directly engage the reverse gear in the forward gear or engage the forward gear in the reverse gear without stopping. The driving gears of the tractor are divided into 5 driving gears including a reverse gear, a hydrostatic forward gear, a forward 1 gear and a forward 2 gear. The hydrostatic gear only realizes the control of the speed ratio through the swing angle of a variable pump in the hydrostatic unit, and other gears realize the continuous change of the speed ratio through the power division of the hydrostatic unit and a mechanical gear clutch.
The mechanical hydraulic stepless speed changer realizes the characteristic of continuous change of the speed ratio through power splitting of the hydrostatic unit and the mechanical gear, but the hydrostatic unit is more complex in composition system and limited by the structure of the mechanical body, so that the speed ratio of the stepless speed changer is unstable, and further analysis shows that the vibration influence of the speed ratio change rate can cause the smoothness of a vehicle to be poor, so that a more reasonable control method is needed to control the speed ratio change rate.
The technical information described above is intended to facilitate a quick understanding of the objects and concepts of the invention, and therefore may contain information and considerations that do not constitute prior art that is well known to those skilled in the art.
Disclosure of Invention
The invention aims to provide a speed ratio change rate control method for a mechanical hydraulic stepless speed changer of a tractor, and solves the problem that the smoothness of the whole tractor is difficult to ensure in the prior art.
The technical scheme of the invention is as follows:
a speed ratio rate control method for a mechano-hydraulic continuously variable transmission of a tractor, comprising the steps of:
1) calculating an expected speed ratio and an expected speed ratio change rate according to a signal currently acquired by the vehicle;
2) judging the current gear operation condition; if only the adjacent gear switching is carried out, executing the step 3); if the gear reversing shuttle is carried out, executing the step 4);
3) desired ratio rate control during adjacent gear shifts
3.1) judging the current driving direction according to the gear state signal of the gearbox; the forward direction comprises a forward 1 gear, a forward 2 gear and a hydrostatic forward gear, and the reverse direction comprises a reverse gear and a hydrostatic reverse gear;
3.2) if the direction is reverse gear direction, giving the lower limit of the saturated nonlinear characteristic of the change rate of the expected speed ratio;
3.3) if the direction is the forward gear direction, giving a limit upper limit of the saturated nonlinear characteristic of the change rate of the expected speed ratio;
3.4) limiting the change rate of the expected speed ratio by determining the limit upper limit/lower limit of the change rate saturation nonlinear characteristic of the expected speed ratio to obtain the change rate of the expected input speed ratio of the vehicle speed ratio change rate output control;
4) desired ratio rate control during reverse gear shuttling
If the logic value of the gear shuttle enabling signal is judged to be 1, the absolute value of the actual speed ratio is taken, and then the fastest t speed ratio is limitedsAfter the time, the expected output speed ratio is reached, the maximum change rate of the speed ratio under the limiting condition is compared with the set maximum change rate of the expected shuttle speed ratio, and the larger value of the maximum change rate and the set maximum change rate of the expected shuttle speed ratio is taken as the maximum value of the change rate of the expected shuttle speed ratio;
5) selecting, in conjunction with the transmission shift enable control, either the rate of change of the desired input speed ratio from step 3) or the maximum rate of change of the desired shuttle speed ratio from step 4) as the rate of change output of the desired output speed ratio.
Further, in step 1), the desired speed ratio gitargetThe calculation formula of (2) is as follows:
Figure GDA0003356995050000021
wherein n iscarrDesired output speed of the planet carrier, nengInputting a rotation speed for the engine;
desired ratio rate of change dgidesThe calculation formula of (2) is as follows:
Figure GDA0003356995050000022
wherein, adesK is a calculation coefficient of the vehicle speed and the output rotation speed of the planet carrier, and the value of k is 46.4688.
Further, the judgment of the current gear operation condition in the step 2) is to determine the gear of the current gearbox by judging the gear state signal of the gearbox.
Further, the step 3.2) is specifically:
judging whether the gear state is hydrostatic reverse gear or not; if yes, calculating a maximum change rate dgi1 of the gear shift ratio, and setting an upper limit parameter and a lower limit parameter of saturated nonlinear characteristics aiming at dgi 1; if not, setting the minimum change rate dgi2 of the speed ratio, and taking the value as the limit lower limit of the saturated nonlinear characteristic of the change rate of the expected speed ratio;
the maximum rate of change dgi1 of the shift ratio is also noted dgiHRThe calculation formula is as follows:
Figure GDA0003356995050000023
wherein, cfgHRIs hydrostatic reverse gear speed ratio synchronization point, gi is actual speed ratio, T is system sampling period, TprepHRThe hydrostatic reverse gear ratio synchronization point is timed up.
Further, step 3.3) is specifically:
judging whether the gear state is a hydrostatic forward gear, if so, calculating a maximum change rate dgi3 of a gear shifting speed ratio, setting upper and lower limit limiting parameters aiming at saturated nonlinear characteristics of dgi3, if not, further judging whether the gear state is a forward 1 gear, if so, setting a minimum change rate dgi4 of the speed ratio, if not, converting a table look-up function of the change rate of the linear speed ratio to obtain dgi5, and taking the minimum value as the upper limit of the saturated nonlinear characteristics of the change rate of the expected speed ratio;
the maximum rate of change dgi3 of the shift ratio is also noted dgiH1The calculation formula is as follows:
Figure GDA0003356995050000031
wherein, cfgH1Is hydrostatic forward gear speed ratio synchronization point, tprepH1The hydrostatic forward gear ratio synchronization point is timed up.
Further, the step 5) is specifically:
judging the logic value of a gear shuttle limiting signal;
if the logic value of the gear shuttle limiting signal is judged to be 0, taking the change rate of the expected input speed ratio as the change rate of the expected output speed ratio;
if the logic value of the gear shuttle limiting signal is judged to be 1, further comparing and judging the change rate of the expected input speed ratio and the maximum change rate of the expected shuttle speed ratio; the maximum rate of change of the desired shuttle speed ratio is taken as the rate of change of the desired output speed ratio if the rate of change of the desired input speed ratio is greater than the maximum rate of change of the desired shuttle speed ratio, otherwise the rate of change of the desired input speed ratio is taken as the rate of change of the desired output speed ratio.
Further, the logical value of the range shuttle limit signal is determined as follows:
and converting the expected speed ratio data type into a logic value (not 0, namely 1), and if the expected speed ratio is not equal to 0, performing logic AND operation on the expected speed ratio and the shuttle shift enable signal, and taking the logic operation value as the shuttle shift limit signal.
Correspondingly, the invention also provides computer equipment which comprises a memory and a processor, wherein the memory stores a computer program, and the processor realizes the steps of the speed ratio change rate control method when executing the computer program.
Accordingly, the present invention also provides a computer readable storage medium having stored thereon a computer program which, when executed by a processor, carries out the steps of the above-described speed ratio change rate control method.
Compared with the prior art, the invention has the following advantages:
the change rate of the speed ratio is controlled, so that the speed ratio is more accurately controlled, and the smoothness of the whole vehicle is improved.
The corresponding hydrostatic gears are limited by the synchronous point reached by the hydrostatic gear speed ratio, the condition that the mechanical gear clutch fluctuates back and forth between combination and disengagement due to the oscillation of the speed ratio change rate caused by the common driving of the hydrostatic gears and the mechanical gears is improved, and the driving feeling of a driver is greatly improved.
Drawings
FIG. 1 is a functional block diagram of a vehicle speed ratio rate control method of the present invention.
FIG. 2 is a schematic diagram of a ratio change rate output control module of FIG. 1.
FIG. 3 is a schematic diagram of a desired ratio rate control module during an adjacent gear shift of FIG. 1.
FIG. 4 is a schematic diagram of a desired ratio rate control module during the shuttle of gears of FIG. 1.
Detailed Description
The invention is described in detail below with reference to the figures and examples.
According to the invention, the speed ratio change rate is controlled, the expected speed ratio change rate is increased to the expected speed ratio, so that the speed ratio is more accurately controlled, the corresponding hydrostatic gear is limited, and the smoothness of the whole vehicle is improved.
In the vehicle speed ratio change rate control process, the input signals are a desired speed ratio change rate, an actual speed ratio, a desired speed ratio, a hydrostatic gear to 1 gear enable flag, a hydrostatic gear to reverse gear enable flag, a transmission gear state signal, and a shuttle gear enable signal.
The expected speed ratio change rate is calculated by collecting data and relates to adjacent gears and shuttle gears.
The actual speed ratio, i.e. the actual speed ratio of the current vehicle, has the value of actual planet carrier speed/engine speed. The actual rotating speed of the planet carrier and the rotating speed of the engine are obtained by collecting data.
A desired speed ratio, i.e., a desired output speed ratio.
From hydrostatic gear to gear 1 enable flag, from hydrostatic gear to reverse enable flag: the initial values of the flag bits are all 0, are obtained by judging conditions, and are compared with an expected speed ratio (the expected speed ratio of upshifting is larger than the actual speed ratio, and the expected speed ratio of downshifting is smaller than the actual speed ratio) to obtain the flag bit value of 1 when the conditions are met.
The gear state signal of the transmission is obtained by judging the actual speed ratio.
As shown in fig. 1, the speed ratio change rate of the vehicle is controlled by the desired speed ratio change rate control module (output in fig. 3) during the adjacent gear shifting, the desired speed ratio change rate control module (output in fig. 4) during the shuttle gear, and the transmission range enable control module, and finally the desired speed ratio change rate (output in fig. 2) is output, and the sum thereof is used as a requested speed ratio to control the transmission (the speed ratio change rates at each cycle are superposed to reach the requested speed ratio, that is, reach the desired speed ratio).
Wherein the desired speed ratio calculation formula:
Figure GDA0003356995050000041
ncarrdesired output speed of the planet carrier, nengThe engine input speed is.
Desired ratio change rate calculation formula:
Figure GDA0003356995050000042
adesk is a calculation coefficient of the vehicle speed and the output rotation speed of the planet carrier for the requested vehicle acceleration.
As shown in fig. 2, for the determination of the change rate of the desired output speed ratio, the input signal includes a shuttle shift limit signal, a change rate of the desired input speed ratio and a maximum change rate of the desired shuttle speed ratio, if the logic value of the shuttle shift limit signal is determined to be 0, the change rate of the desired input speed ratio is taken as the change rate of the desired output speed ratio, otherwise, if the logic value of the shuttle shift limit signal is determined to be 1, the further determination is made, if the change rate of the desired input speed ratio is greater than the maximum change rate of the desired shuttle speed ratio, the maximum change rate of the desired shuttle speed ratio is taken as the change rate of the desired output speed ratio, otherwise, the change rate of the desired input speed ratio is taken as the change rate of the desired output speed ratio. The rate of change of the desired output speed ratio is ultimately output.
As shown in FIG. 3, a desired speed ratio change rate control block during an adjacent gear shift outputs a desired input speed ratio change rate (input to the vehicle speed ratio change rate output control module shown in FIG. 1).
The vehicle driving gears in the embodiment are divided into 5 driving gears including a reverse gear, a hydrostatic forward gear, a forward 1 gear and a forward 2 gear.
Firstly, judging the driving direction;
and if the gear state is in the reverse gear direction, further judging whether the gear state is hydrostatic reverse gear, if so, calculating a maximum change rate dgi1 of the gear shifting speed ratio, setting upper and lower limit limiting parameters aiming at the saturated nonlinear characteristic of dgi1, and if not, setting a minimum change rate dgi2 of the speed ratio and taking the value of the minimum change rate as a lower limit of the saturated nonlinear characteristic of the change rate of the expected speed ratio.
And if the gear state is in the forward gear direction, further judging whether the gear state is a hydrostatic forward gear, if so, calculating a maximum change rate dgi3 of the gear shifting speed ratio, setting upper and lower limit limiting parameters aiming at the saturated nonlinear characteristic of dgi3, if not, further judging whether the gear state is a forward 1 gear, if so, setting a minimum change rate dgi4 of the speed ratio, if not, converting a table look-up function of the change rate of the linear speed ratio to obtain dgi5, and taking the minimum value as the upper limit of the saturated nonlinear characteristic of the change rate of the expected speed ratio.
The desired input speed ratio rate of change is limited by setting upper and lower limits.
The rate of change dgi1 of the speed ratio is calculated as follows:
Figure GDA0003356995050000051
wherein, cfgHRIs hydrostatic reverse gear speed ratio synchronization point, gi is actual speed ratio, T is system sampling period, TprepHRThe hydrostatic reverse gear ratio synchronization point is timed up.
The rate of change dgi3 of the speed ratio is calculated as follows:
Figure GDA0003356995050000052
wherein, cfgH1Is hydrostatic forward gear speed ratio synchronization point, tprepH1Synchronizing hydrostatic forward gear ratiosThe point reaches the time.
As shown in fig. 4, which is a control diagram of a desired speed ratio change rate during the gear shuttling process, the input signals are: actual speed ratio and shuttle enable signal.
If the logic value of the gear shuttle enabling signal is judged to be 1 (indicating that the driver performs gear shuttle instruction operation, namely vehicle driving reversing operation is performed in a cab), the absolute value of the actual speed ratio is taken, and then the fastest speed t of the speed ratio is limitedsAnd finally, taking the maximum value of the two values as the maximum value of the change rate of the expected shuttle speed ratio.
If the logic value of the shuttle shift enable signal is judged to be 0, the driver does not perform shuttle shift operation, the speed ratio change rate is 0 at the moment, and the 0 value is compared with the set maximum change rate of the expected shuttle speed ratio.
The input signals for the transmission shift enable control are: a desired speed ratio and a shuttle enable signal. And if the expected speed ratio is not equal to 0, performing logical AND operation on the expected speed ratio and the gear shuttle enabling signal, and taking the logical operation value as the gear shuttle limiting signal.
Take a mechanical hydraulic stepless speed changer for a high-horsepower tractor as an example: the tractor can realize that the driver can directly engage the reverse gear in the forward gear or engage the forward gear in the reverse gear without stopping. The driving gears of the tractor are divided into 5 driving gears including a reverse gear, a hydrostatic forward gear, a forward 1 gear and a forward 2 gear. The hydrostatic gear only realizes the control of the speed ratio through the swing angle of a variable pump in the hydrostatic unit, and other gears realize the continuous change of the speed ratio through the power division of the hydrostatic unit and a mechanical gear clutch.
The specific control method is as follows:
firstly, a desired speed ratio and a desired speed ratio change rate are obtained by calculating signals collected by a vehicle, and the signals and an actual speed ratio, a static hydraulic gear to 1 gear enabling mark bit, a static hydraulic gear to reverse gear enabling mark bit, a transmission gear state signal and a gear shuttle enabling signal are used as input signals for controlling the speed ratio change rate.
Desired speed ratio calculation formula:
Figure GDA0003356995050000061
wherein n iscarrDesired output speed of the planet carrier, nengInputting a rotation speed for the engine;
engine input speed nengSignals obtained for acquiring data;
desired output speed n of the planet carriercarrIs obtained through a series of calculations, and the percentage of the driver stepping on the accelerator pedal is input, and the percentage of the accelerator pedal is converted into the expected speed and then converted into the expected rotating speed.
ncarr＝perDrvpedal*0.01*vMax*K
K is the calculation coefficient of the vehicle speed and the output rotating speed of the planet carrier, vMaxThe maximum forward vehicle speed of the vehicle is 50Km/h, and the maximum reverse vehicle speed of the vehicle is 20 Km/h; wherein, the percentage of the accelerator pedal is as follows: 0 to 100 percent
Calculating the formula: perDrvpedal＝(uSensor–(Vss*0,1))*(100/(Vss*0,9-Vss*0,1)
The value of the actual collected voltage signal is uSensor, and the maximum measuring range of the voltage sensor is Vss.
Desired ratio change rate calculation formula:
Figure GDA0003356995050000071
wherein, adesFor requested vehicle acceleration, adesDv/dt (the change of the vehicle speed in unit time is the acceleration), and the vehicle speed is a signal obtained by collecting data; k is a calculation coefficient of the vehicle speed and the output rotating speed of the planet carrier, and the value of k is 46.4688.
Then, the operation or condition judgment is performed for different logic modules.
A. When the driver only switches adjacent gears, the expected speed ratio change rate in the process of switching the adjacent gears needs to be controlled. Firstly, judging the driving direction, if the driving direction is the reverse gear direction, further judging whether the gear state is hydrostatic reverse gear, if the gear state is hydrostatic reverse gear, calculating the maximum change rate dgi1 of the gear shifting speed ratio, and setting upper and lower limit limiting parameters of the saturated nonlinear characteristic, wherein the upper limit is 0.0005, and the lower limit is-0.006. If not, a minimum rate of change dgi2 of the speed ratio is set, having a value of-0.006, which is taken as the lower limit of the rate of change saturation nonlinear characteristic limit of the desired speed ratio. And if the direction is the forward gear direction, further judging whether the gear state is the hydrostatic forward gear, if so, calculating a maximum change rate dgi3 of the gear shift ratio, and setting upper and lower limit limiting parameters of the saturated nonlinear characteristic, wherein the upper limit is 0.006, and the lower limit is 0.0005. If not, whether the gear state is the forward 1 gear is further judged, if so, the minimum change rate dgi4 of the speed ratio is set, the value is 0.006, if not, the change rate table lookup function of the linear speed ratio is converted to obtain dgi5, and the minimum value is used as the limit upper limit of the saturated nonlinear characteristic of the change rate of the expected speed ratio. The desired input speed ratio rate of change is limited by setting upper and lower limits.
The rate of change dgi1 of the speed ratio is calculated as follows:
Figure GDA0003356995050000072
wherein, cfgHRIs hydrostatic reverse gear speed ratio synchronization point, gi is actual speed ratio, T is system sampling period, TprepHRThe hydrostatic reverse gear ratio synchronization point is timed up.
The rate of change dgi3 of the speed ratio is calculated as follows:
Figure GDA0003356995050000073
wherein, cfgH1Is hydrostatic forward gear speed ratio synchronization point, tprepH1The hydrostatic forward gear ratio synchronization point is timed up.
In the embodiments of the present inventionIn the above calculation formula, the parameter cfgHRValue 0.2043, cfgH1The value is-0.2097, T is 0.01s, TprepHRThe value is 0.5s, tprepH1The value was 0.5 s.
The rate of change dgi5 of the ratio is looked up as follows:
Figure GDA0003356995050000081
B. when a driver performs gear reversing shuttle, the expected speed ratio change rate in the gear shuttle process needs to be controlled. The situation that the driving direction is reversed and the reverse gear forward 1 gear, the reverse gear forward 2 gear and the like are shuttled between 5 driving gears can occur, and the situation is totally 12. The input signal of an expected speed ratio change rate control module in the gear shuttling process comprises an actual speed ratio and a gear shuttling enabling signal, if the logic value of the gear shuttling enabling signal is judged to be 1, an absolute value of the actual speed ratio is taken, the absolute value is multiplied by a sampling period of 0.01s, then the sampling period is divided by 2s to limit the time when the speed ratio reaches the expected output speed ratio at the fastest speed, meanwhile, the absolute value is compared with a maximum change rate setting parameter of the expected shuttling speed ratio of 0.004, and finally the maximum value of the absolute value and the maximum value of the maximum change rate setting parameter of the expected shuttling speed ratio is taken as the maximum value of the change rate of the expected shuttling speed ratio.
And finally, inputting the speed ratio change rate into a speed ratio change rate output control module for condition judgment.
Before judgment, logical operation needs to be carried out on the gear shuttle enabling signals, if the expected speed ratio is not equal to 0, logical AND operation is carried out on the expected speed ratio and the gear shuttle enabling signals, and the logical operation value is used as the gear shuttle limiting signals. And further taking the change rate of the expected input speed ratio as the change rate of the expected output speed ratio if the logical value of the shuttle gear limiting signal is judged to be 0, otherwise, further judging if the logical value of the shuttle gear limiting signal is judged to be 1, taking the maximum change rate of the expected shuttle speed ratio as the change rate of the expected output speed ratio if the change rate of the expected input speed ratio is greater than the maximum change rate of the expected shuttle speed ratio, and otherwise, taking the change rate of the expected input speed ratio as the change rate of the expected output speed ratio. The rate of change of the desired output speed ratio is ultimately output. The speed ratio is increased to the expected speed ratio, so that the speed ratio is more accurately controlled, corresponding hydrostatic gears are limited, and the smoothness of the whole vehicle is improved.
The invention realizes the speed ratio change rate control of the mechanical hydraulic stepless speed changer of the high-horsepower tractor, thereby more accurately controlling the speed ratio, limiting the corresponding hydrostatic gear through the synchronous point reached by the hydrostatic gear speed ratio and improving the smoothness of the whole tractor.

Claims (5)

1. A speed ratio change rate control method for a mechano-hydraulic continuously variable transmission of a tractor, characterized by comprising the steps of:
1) calculating an expected speed ratio and an expected speed ratio change rate according to a signal currently acquired by the vehicle;
in step 1), the desired speed ratio gitargetThe calculation formula of (2) is as follows:
Figure FDA0003356995040000011
wherein n iscarrDesired output speed of the planet carrier, nengInputting a rotation speed for the engine;
desired ratio rate of change dgidesThe calculation formula of (2) is as follows:
Figure FDA0003356995040000012
wherein, adesK is a calculation coefficient of the vehicle speed and the output rotating speed of the planet carrier, and the value of k is 46.4688;
2) judging the current gear operation condition; if only the adjacent gear switching is carried out, executing the step 3); if the gear reversing shuttle is carried out, executing the step 4);
3) desired ratio rate control during adjacent gear shifts
3.1) judging the current driving direction according to the gear state signal of the gearbox; the forward direction comprises a forward 1 gear, a forward 2 gear and a hydrostatic forward gear, and the reverse direction comprises a reverse gear and a hydrostatic reverse gear;
3.2) if the direction is reverse gear direction, giving the lower limit of the saturated nonlinear characteristic of the change rate of the expected speed ratio;
the step 3.2) is specifically as follows:
judging whether the gear state is hydrostatic reverse gear or not; if yes, calculating a maximum change rate dgi1 of the gear shift ratio, and setting an upper limit parameter and a lower limit parameter of saturated nonlinear characteristics aiming at dgi 1; if not, setting the minimum change rate dgi2 of the speed ratio, and taking the value as the limit lower limit of the saturated nonlinear characteristic of the change rate of the expected speed ratio;
the maximum rate of change dgi1 of the shift ratio is also noted dgiHRThe calculation formula is as follows:
Figure FDA0003356995040000013
wherein, cfgHRIs hydrostatic reverse gear ratio synchronization point, giFor the actual speed ratio, T is the system sampling period, TprepHRThe hydrostatic reverse gear ratio synchronization point arrival time;
3.3) if the direction is the forward gear direction, giving a limit upper limit of the saturated nonlinear characteristic of the change rate of the expected speed ratio;
the step 3.3) is specifically as follows:
judging whether the gear state is a hydrostatic forward gear, if so, calculating a maximum change rate dgi3 of a gear shifting speed ratio, setting upper and lower limit limiting parameters aiming at saturated nonlinear characteristics of dgi3, if not, further judging whether the gear state is a forward 1 gear, if so, setting a minimum change rate dgi4 of the speed ratio, if not, converting a table look-up function of the change rate of the linear speed ratio to obtain dgi5, and taking the minimum value as the upper limit of the saturated nonlinear characteristics of the change rate of the expected speed ratio;
the maximum rate of change dgi3 of the shift ratio is also noted dgiH1The calculation formula is as follows:
Figure FDA0003356995040000021
wherein, cfgH1Is hydrostatic forward gear speed ratio synchronization point, tprepH1The hydrostatic forward gear speed ratio synchronization point arrival time;
3.4) limiting the change rate of the expected speed ratio by determining the limit upper limit/lower limit of the change rate saturation nonlinear characteristic of the expected speed ratio to obtain the change rate of the expected input speed ratio of the vehicle speed ratio change rate output control;
4) desired ratio rate control during reverse gear shuttling
If the logic value of the gear shuttle enabling signal is judged to be 1, the absolute value of the actual speed ratio is taken, and then the fastest t speed ratio is limitedsAfter the time, the expected output speed ratio is reached, the maximum change rate of the speed ratio under the limiting condition is compared with the set maximum change rate of the expected shuttle speed ratio, and the larger value of the maximum change rate and the set maximum change rate of the expected shuttle speed ratio is taken as the maximum value of the change rate of the expected shuttle speed ratio;
5) selecting, in conjunction with transmission shift enable control, either the rate of change of the desired input speed ratio from step 3) or the maximum rate of change of the desired shuttle speed ratio from step 4) as the rate of change output of the desired output speed ratio;
the step 5) is specifically as follows:
judging the logic value of a gear shuttle limiting signal;
if the logic value of the gear shuttle limiting signal is judged to be 0, taking the change rate of the expected input speed ratio as the change rate of the expected output speed ratio;
if the logic value of the gear shuttle limiting signal is judged to be 1, further comparing and judging the change rate of the expected input speed ratio and the maximum change rate of the expected shuttle speed ratio; the maximum rate of change of the desired shuttle speed ratio is taken as the rate of change of the desired output speed ratio if the rate of change of the desired input speed ratio is greater than the maximum rate of change of the desired shuttle speed ratio, otherwise the rate of change of the desired input speed ratio is taken as the rate of change of the desired output speed ratio.
2. The method as claimed in claim 1, wherein the determination of the current gear operation condition in step 2) is a determination of the current gear of the transmission by determining the transmission gear state signal.
3. A method of ratio rate control for a tractor mechano-hydraulic continuously variable transmission as claimed in claim 1 wherein said range shuttle limit signal logic value is determined as follows:
and converting the expected speed ratio data type into a logic value, and if the expected speed ratio is not equal to 0, performing logic AND operation on the expected speed ratio and the shuttle shift enable signal, and taking the logic operation value as the shuttle shift limit signal.
4. A computer device comprising a memory and a processor, the memory storing a computer program, wherein the processor when executing the computer program implements the steps of the speed ratio change rate control method of any one of claims 1 to 3.
5. A computer-readable storage medium, having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the ratio change rate control method of any of claims 1-3.
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