CN114909470B - Speed ratio control method for automobile downhill road with continuously variable automatic transmission - Google Patents
Speed ratio control method for automobile downhill road with continuously variable automatic transmission Download PDFInfo
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- CN114909470B CN114909470B CN202210613739.4A CN202210613739A CN114909470B CN 114909470 B CN114909470 B CN 114909470B CN 202210613739 A CN202210613739 A CN 202210613739A CN 114909470 B CN114909470 B CN 114909470B
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Classifications
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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
- F16H61/66—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 specially adapted for continuously variable gearings
- F16H61/662—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 specially adapted for continuously variable gearings with endless flexible members
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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
- F16H59/00—Control inputs to control units of change-speed- or reversing-gearings for conveying rotary motion
- F16H59/14—Inputs being a function of torque or torque demand
- F16H59/24—Inputs being a function of torque or torque demand dependent on the throttle opening
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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
- F16H59/00—Control inputs to control units of change-speed- or reversing-gearings for conveying rotary motion
- F16H59/48—Inputs being a function of acceleration
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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
- F16H59/00—Control inputs to control units of change-speed- or reversing-gearings for conveying rotary motion
- F16H59/50—Inputs being a function of the status of the machine, e.g. position of doors or safety belts
- F16H59/54—Inputs being a function of the status of the machine, e.g. position of doors or safety belts dependent on signals from the brakes, e.g. parking brakes
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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
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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
- F16H61/14—Control of torque converter lock-up clutches
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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
- F16H61/21—Providing engine brake control
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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
- F16H59/00—Control inputs to control units of change-speed- or reversing-gearings for conveying rotary motion
- F16H59/02—Selector apparatus
- F16H59/08—Range selector apparatus
- F16H2059/082—Range selector apparatus for different transmission modes
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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
- F16H59/00—Control inputs to control units of change-speed- or reversing-gearings for conveying rotary motion
- F16H59/60—Inputs being a function of ambient conditions
- F16H59/66—Road conditions, e.g. slope, slippery
- F16H2059/663—Road slope
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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
- F16H2061/0244—Adapting the automatic ratio to direct driver requests, e.g. manual shift signals or kick down
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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
- F16H61/66—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 specially adapted for continuously variable gearings
- F16H2061/6604—Special control features generally applicable to continuously variable gearings
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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
- F16H61/66—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 specially adapted for continuously variable gearings
- F16H61/662—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 specially adapted for continuously variable gearings with endless flexible members
- F16H2061/66204—Control for modifying the ratio control characteristic
- F16H2061/66209—Control for modifying the ratio control characteristic dependent on ambient conditions
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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
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
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Abstract
The invention discloses a speed ratio control method for a downhill road of an automobile with a continuously variable automatic transmission, which comprises the following steps: step one: firstly, judging the intention of a driver and the condition of a road; step two: detecting driver intention through brake and accelerator signals; step three: when the accelerator is 0, the driver can judge that the acceleration is not needed, and if the acceleration of the vehicle is still greater than 0, the vehicle can judge that the vehicle is going downhill and is accelerated under the influence of gravity; step four: when the acceleration is larger than the threshold value, the speed ratio of the transmission can be controlled, the engine speed is increased, the braking force transmitted to wheels by the engine is increased, and therefore the vehicle acceleration is reduced.
Description
Technical Field
The invention relates to the technical field of vehicle control, in particular to a speed ratio control method for an automobile downhill road with a continuously variable automatic transmission.
Background
The speed ratio of the automatic gearbox carried by the traditional fuel automobile is controlled to adjust the rotation speed of the engine to a lower rotation speed interval, so that the purposes of saving fuel, reducing engine noise and the like when the automobile slides are achieved. When the vehicle runs on a downhill road, the speed ratio control is the same as that of the vehicle running on a straight road, the engine keeps running at a low rotating speed and cannot provide enough reverse traction force, and the vehicle speed is faster and faster. Frequent braking by a driver is required, driving comfort is reduced, and along with the improvement of the intelligent degree of an automobile, the automatic transmission is required to be more intelligent in gear shifting, if a speed ratio control strategy which can be distinguished when the automatic transmission slides downhill is identified, the engine speed is increased when the automatic transmission slides downhill, and therefore the acceleration of the downhill is reduced.
Conventional gear control requires frequent driver braking to control vehicle speed when the vehicle is coasting downhill. The driving comfort is reduced, and once the experience of a driver is insufficient, the vehicle is easy to run down a slope and the speed is too high, so that the dangerous condition of overspeed driving occurs. The long-time braking on the long-downslope road is easy to occur braking force attenuation of the braking system, and danger is caused.
The electric automobile can control the motor to output negative torque, and the speed of the downhill vehicle is controlled by torque control, so that the method cannot be applied to the fuel oil vehicle. The negative torque of the fuel engine is generated by running resistance, and the running resistance is related to the engine speed when the environmental factors are unchanged. While a transmission with limited gear such as DCT, AT, AMT is required to change the engine speed by controlling the speed ratio of the transmission so as to change the torque transmitted to the wheel ends, the engine speed is changed in a step-like manner during gear shifting, and the engine speed cannot be controlled continuously.
Disclosure of Invention
The invention aims to provide a speed ratio control method for a downhill road of an automobile with a continuously variable automatic transmission, which aims to solve the problems in the prior art.
In order to achieve the above purpose, the present invention provides the following technical solutions:
A speed ratio control method for a downhill road of an automobile with a continuously variable automatic transmission comprises the following steps:
Step one: firstly, judging the intention of a driver and the condition of a road;
Step two: detecting the intention of a driver through brake and accelerator signals, calculating the actual acceleration of the vehicle through vehicle speed derivation, performing low-pass filtering, and judging the road ramp state of the vehicle by using the filtered acceleration signals;
Step three: when the accelerator is 0, the driver can judge that the acceleration is not needed, and if the acceleration of the vehicle is still greater than 0, the vehicle can judge that the vehicle is going downhill and is accelerated under the influence of gravity;
step four: when the acceleration is greater than the threshold value, the speed ratio of the transmission can be controlled to increase the rotation speed of the engine and the braking force transmitted to wheels by the engine, so that the acceleration of the vehicle is reduced.
As a further scheme of the invention: the method comprises the following specific steps:
S1: the vehicle can lock the hydraulic torque converter after reaching a higher speed, the transmission from the engine to the wheels after the hydraulic torque converter is locked can be regarded as rigid connection, and the rotating speed of the engine is equal to the rotating speed of the turbine, so that the negative torque of the engine can be effectively transmitted to the wheels;
s2: obtaining acceleration of the vehicle by deriving a vehicle speed signal, and filtering the acceleration signal;
S3: if the brake pedal is further detected to be stepped down, the driver is considered to be required to be decelerated, the gearbox controller activates a downhill mode, and the speed ratio control enters closed-loop control related to acceleration;
S4: in a downhill mode, the acceleration a and the speed ratio of the vehicle are controlled in a closed loop mode;
s5: preventing the engine speed from being too high or too low in the downhill mode;
s6: the upper speed ratio limit value is a table related to the vehicle speed, the minimum speed ratio limit value is a speed ratio value of sliding with a default of 0 accelerator, and the speed ratio cannot be smaller than the speed ratio value of 0 accelerator in a downhill mode;
s7: the acceleration is smaller than 0, the speed ratio reaches the lower limit value, and the downhill mode is exited after the duration t 3;
s8: the driver presses the accelerator pedal to indicate that acceleration is required and exits the downhill mode.
As still further aspects of the invention: the transmission controller in the step S1 receives an accelerator opening degree, a brake signal and a vehicle speed signal on CAN communication to detect the intention of a driver and the state of the vehicle.
As still further aspects of the invention: in the step S2, when the accelerator opening signal is 0 and the acceleration is greater than 0, it is determined that the vehicle is accelerating on the downhill road at this time.
As still further aspects of the invention: in the step S4, the acceleration rate is greater than the calibration value a1, the speed ratio is increased to increase the engine speed to increase the engine reverse braking force, the acceleration rate is less than the calibration value a2, the speed ratio is reduced to decrease the engine speed to decrease the engine reverse braking force, wherein a1> a2, and in the ramp mode, the speed ratio of the belt wheels is kept unchanged when the vehicle acceleration is in the interval a2= < a= < a 1.
As still further aspects of the invention: in the step S5, the adjusting range of the engine speed is limited by limiting the upper and lower speed ratio limits during sliding, the speed ratio is not increased after the upper speed ratio limit is reached, only the speed ratio is allowed to be maintained or reduced, and the engine speed is not increased. When the lower limit of the speed ratio is reached, the speed ratio is not reduced any more, and only the speed ratio is allowed to be maintained or increased, the engine speed is not reduced any more.
Compared with the prior art, the invention has the beneficial effects that:
The invention benefits from the fact that the speed ratio of the stepless automatic transmission can be continuously changed, and the speed ratio can be finely controlled. The speed ratio and the acceleration are subjected to closed-loop control, the braking force of the engine is increased when the vehicle descends, the sliding acceleration of the vehicle is reduced, the braking times of a driver are reduced, the driving comfort is improved, the heating of a brake is reduced, and the safety and the comfort of the descending working condition are improved.
Drawings
Fig. 1 is a power transmission path diagram of a typical continuously variable transmission.
FIG. 2 is a schematic diagram of a typical 0-accelerator pedal downhill project activating and exiting a downhill mode.
FIG. 3 is a schematic diagram of activating a downhill mode and exiting the downhill mode.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1 to 3, in an embodiment of the present invention, a speed ratio control method for a downhill road of an automobile with a continuously variable automatic transmission is provided, which includes the following steps:
Step one: firstly, judging the intention of a driver and the condition of a road;
Step two: detecting the intention of a driver through brake and accelerator signals, calculating the actual acceleration of the vehicle through vehicle speed derivation, performing low-pass filtering, and judging the road ramp state of the vehicle by using the filtered acceleration signals;
Step three: when the accelerator is 0, the driver can judge that the acceleration is not needed, and if the acceleration of the vehicle is still greater than 0, the vehicle can judge that the vehicle is going downhill and is accelerated under the influence of gravity;
Step four: when the acceleration is larger than the threshold value, the speed ratio of the transmission can be controlled, the rotating speed of the engine is increased, and the braking force transmitted to wheels by the engine is increased, so that the acceleration of the vehicle is reduced;
The method comprises the following specific steps:
S1: when the vehicle reaches a higher speed, the hydraulic torque converter is locked, the transmission from the engine to the wheels after the hydraulic torque converter is locked can be regarded as rigid connection, and the engine rotation speed is equal to the turbine rotation speed, so that the negative torque of the engine can be effectively transmitted to the wheels. The transmission controller receives an accelerator opening degree, a brake signal and a vehicle speed signal on CAN communication and is used for detecting the intention of a driver and the state of a vehicle;
s2: the vehicle speed signal is derived to obtain the acceleration of the vehicle, and the acceleration signal is filtered. When the accelerator opening signal is 0 and the acceleration is greater than 0, judging that the vehicle is accelerated to slide on a downhill road at the moment;
S3: if the brake pedal is further detected to be stepped down, the driver is considered to be required to be decelerated, the gearbox controller activates a downhill mode, and the speed ratio control enters closed-loop control related to acceleration;
S4: in the downhill mode, the vehicle acceleration a and the speed ratio are subjected to closed loop control, the speed ratio is increased to increase the engine speed to increase the engine reverse towing braking force when the acceleration is larger than a calibration value a1, the speed ratio is reduced to decrease the engine speed to decrease the engine reverse towing braking force when the acceleration is smaller than a calibration value a2, wherein a1> a2, and in the hill mode, the speed ratio of the belt wheels is kept unchanged when the vehicle acceleration is in a section of a2= < a= < a 1;
S5: the engine speed is prevented from being too high or too low in the downhill mode, the adjusting range of the engine speed is limited by limiting the upper and lower speed ratio limits in the sliding mode, the speed ratio is not increased after the upper speed ratio limit is reached, only the speed ratio is allowed to be maintained or reduced, and the engine speed is not increased. When the lower limit of the speed ratio is reached, the speed ratio is not reduced any more, and only the speed ratio is allowed to be maintained or increased, the engine speed is not reduced any more;
s6: the upper speed ratio limit value is a table related to the vehicle speed, the minimum speed ratio limit value is a speed ratio value of sliding with a default of 0 accelerator, and the speed ratio cannot be smaller than the speed ratio value of 0 accelerator in a downhill mode;
s7: the acceleration is smaller than 0, the speed ratio reaches the lower limit value, and the downhill mode is exited after the duration t 3;
s8: the driver presses the accelerator pedal to indicate that acceleration is required and exits the downhill mode.
Examples
The power transmission parameters of a certain vehicle are as follows
Engine speed n=vehicle speed v_fd_j_vr_j_ TcLock _j_d 60×1000/(r 2×3.14×3600) =46.6×v_j_vr;
the upper and lower speed ratio limits of the ramp mode calibrated in the range of 30-120km/h are shown in the following table, and the speed ratio limit is obtained through vehicle speed interpolation.
The downhill mode identification and speed ratio control process is as follows:
The vehicle forward gear is driven on a downhill road, at the moment, the locking hydraulic torque converter is in a locking state, the TCU detects the vehicle speed, signals of an accelerator pedal and a brake pedal, and the vehicle acceleration is calculated by deriving the vehicle speed signals and is subjected to low-pass filtering processing. When the opening degree of the accelerator pedal is detected to be 0, the acceleration of the vehicle is larger than 0, and the vehicle can be judged to slide on a downhill slope. When the acceleration is larger than a1 (0.02 m/s 2), the acceleration is judged to be too fast, if the brake pedal is detected to be depressed, the driver can judge that the acceleration is too large and the vehicle speed needs to be controlled, at the moment, a downhill mode is activated, and the speed ratio enters closed-loop control.
Assuming that the vehicle speed is 60km/h at this time, the pulley speed ratio j_vr=0.50, the engine speed is 1398rpm. The acceleration and the pulley speed ratio are subjected to closed-loop control, the acceleration a & gta 1 (0.02 m/s & lt 2 & gt) increases the pulley speed ratio, and the acceleration a & lt 2 & gt (0 m/s & lt 2 & gt) decreases the pulley speed ratio. As the pulley speed ratio increases to 0.7, the engine speed increases to 1957.2rpm, the acceleration a= < a1, the engine speed no longer increases, and the vehicle remains slowly accelerating to a vehicle speed of 63km/h. The road ramp is changed so that the acceleration a < a2 (0 m/s 2), the speed ratio of the belt wheel is reduced by the speed ratio controller, at the speed of 60km/h, the speed ratio j_vr=0.45, the engine speed is 1258.2rpm, the acceleration a < a2 (0 m/s 2), the speed ratio reaches the minimum limit value, and the vehicle exits the downhill mode.
The vehicle forward gear is driven on a downhill road, at the moment, the locking hydraulic torque converter is in a locking state, the TCU detects the vehicle speed, signals of an accelerator pedal and a brake pedal, and the vehicle acceleration is calculated by deriving the vehicle speed signals and is subjected to low-pass filtering processing. When the opening degree of the accelerator pedal is detected to be 0, the acceleration of the vehicle is larger than 0, and the vehicle can be judged to slide on a downhill slope. When the acceleration is larger than a1 (0.02 m/s 2), the acceleration is judged to be too fast, if the brake pedal is detected to be depressed, the driver can judge that the acceleration is too large and the vehicle speed needs to be controlled, at the moment, a downhill mode is activated, and the speed ratio enters closed-loop control.
Assuming that the vehicle speed is 50km/h at this time, the pulley speed ratio j_vr=0.62, the engine speed is 1444.6rpm. The acceleration and the pulley speed ratio are subjected to closed-loop control, the acceleration a & gta 1 (0.02 m/s & lt 2 & gt) increases the pulley speed ratio, and the acceleration a & lt 2 & gt (0 m/s & lt 2 & gt) decreases the pulley speed ratio. As the pulley speed ratio increases to 0.8, the engine speed increases to 1864rpm, the acceleration a= < a1, the engine speed no longer increases, and the vehicle remains slowly accelerating to a vehicle speed of 55km/h. The road ramp is unchanged, the driver presses the accelerator pedal, the gearbox controller detects that the driver needs to accelerate, and the vehicle exits the downhill mode.
Although the present invention has been described with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described, or equivalents may be substituted for elements thereof, and any modifications, equivalents, improvements and changes may be made without departing from the spirit and principles of the present invention.
Claims (5)
1. A speed ratio control method for a downhill road of an automobile with a continuously variable automatic transmission is characterized by comprising the following steps of: the method comprises the following steps:
Step one: firstly, judging the intention of a driver and the condition of a road;
Step two: detecting the intention of a driver through brake and accelerator signals, calculating the actual acceleration of the vehicle through vehicle speed derivation, performing low-pass filtering, and judging the road ramp state of the vehicle by using the filtered acceleration signals;
Step three: when the accelerator is 0, the driver can judge that the acceleration is not needed, and if the acceleration of the vehicle is still greater than 0, the vehicle can judge that the vehicle is going downhill and is accelerated under the influence of gravity;
Step four: when the acceleration is larger than the threshold value, the speed ratio of the transmission can be controlled, the rotating speed of the engine is increased, and the braking force transmitted to wheels by the engine is increased, so that the acceleration of the vehicle is reduced;
The method comprises the following specific steps:
S1: the vehicle can lock the hydraulic torque converter after reaching a higher speed, the transmission from the engine to the wheels after the hydraulic torque converter is locked can be regarded as rigid connection, and the rotating speed of the engine is equal to the rotating speed of the turbine, so that the negative torque of the engine can be effectively transmitted to the wheels;
s2: obtaining acceleration of the vehicle by deriving a vehicle speed signal, and filtering the acceleration signal;
S3: if the brake pedal is further detected to be stepped down, the driver is considered to be required to be decelerated, the gearbox controller activates a downhill mode, and the speed ratio control enters closed-loop control related to acceleration;
S4: in a downhill mode, the acceleration a and the speed ratio of the vehicle are controlled in a closed loop mode;
s5: preventing the engine speed from being too high or too low in the downhill mode;
s6: the upper speed ratio limit value is a table related to the vehicle speed, the minimum speed ratio limit value is a speed ratio value of sliding with a default of 0 accelerator, and the speed ratio cannot be smaller than the speed ratio value of 0 accelerator in a downhill mode;
s7: the acceleration is smaller than 0, the speed ratio reaches the lower limit value, and the downhill mode is exited after the duration t 3;
s8: the driver presses the accelerator pedal to indicate that acceleration is required and exits the downhill mode.
2. The speed ratio control method for a downhill road of an automobile equipped with a continuously variable automatic transmission according to claim 1, characterized in that: the transmission controller in the step S1 receives an accelerator opening degree, a brake signal and a vehicle speed signal on CAN communication to detect the intention of a driver and the state of the vehicle.
3. The speed ratio control method for a downhill road of an automobile equipped with a continuously variable automatic transmission according to claim 1, characterized in that: in the step S2, when the accelerator opening signal is 0 and the acceleration is greater than 0, it is determined that the vehicle is accelerating on the downhill road at this time.
4. The speed ratio control method for a downhill road of an automobile equipped with a continuously variable automatic transmission according to claim 1, characterized in that: in the step S4, the acceleration rate is greater than the calibration value a1, the speed ratio is increased to increase the engine speed to increase the engine reverse braking force, the acceleration rate is less than the calibration value a2, the speed ratio is reduced to decrease the engine speed to decrease the engine reverse braking force, wherein a1> a2, and in the ramp mode, the speed ratio of the belt wheels is kept unchanged when the vehicle acceleration is in the interval a2= < a= < a 1.
5. The speed ratio control method for a downhill road of an automobile equipped with a continuously variable automatic transmission according to claim 1, characterized in that: in the step S5, the adjusting range of the engine speed is limited by limiting the upper and lower speed ratio limits during sliding, the speed ratio is not increased after the upper speed ratio limit is reached, only the speed ratio is allowed to be maintained or reduced, and the engine speed is not increased; when the lower limit of the speed ratio is reached, the speed ratio is not reduced any more, and only the speed ratio is allowed to be maintained or increased, the engine speed is not reduced any more.
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| CN116608263B (en) * | 2023-07-21 | 2023-09-26 | 三一重型装备有限公司 | Vehicle control method and device, electronic equipment and vehicle |
| CN120080938B (en) * | 2025-04-30 | 2025-07-18 | 浙江春风动力股份有限公司 | All-terrain vehicle and downhill braking method thereof |
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