CN110155051B - Fuel-saving control method for truck speed change cruise - Google Patents

Fuel-saving control method for truck speed change cruise Download PDF

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Publication number
CN110155051B
CN110155051B CN201910358195.XA CN201910358195A CN110155051B CN 110155051 B CN110155051 B CN 110155051B CN 201910358195 A CN201910358195 A CN 201910358195A CN 110155051 B CN110155051 B CN 110155051B
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cruise
speed
vehicle
control
engine
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CN110155051A (en
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王玉海
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Qingdao Automotive Research Institute Jilin University
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Qingdao Automotive Research Institute Jilin University
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60WCONJOINT 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
    • B60W10/00Conjoint control of vehicle sub-units of different type or different function
    • B60W10/04Conjoint control of vehicle sub-units of different type or different function including control of propulsion units
    • B60W10/06Conjoint control of vehicle sub-units of different type or different function including control of propulsion units including control of combustion engines
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60WCONJOINT 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
    • B60W10/00Conjoint control of vehicle sub-units of different type or different function
    • B60W10/10Conjoint control of vehicle sub-units of different type or different function including control of change-speed gearings
    • B60W10/11Stepped gearings
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60WCONJOINT 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
    • B60W10/00Conjoint control of vehicle sub-units of different type or different function
    • B60W10/18Conjoint control of vehicle sub-units of different type or different function including control of braking systems
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60WCONJOINT 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
    • B60W30/00Purposes 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, or advanced driver assistance systems for ensuring comfort, stability and safety or drive control systems for propelling or retarding the vehicle
    • B60W30/14Adaptive cruise control
    • B60W30/143Speed control
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D11/00Arrangements for, or adaptations to, non-automatic engine control initiation means, e.g. operator initiated
    • F02D11/06Arrangements for, or adaptations to, non-automatic engine control initiation means, e.g. operator initiated characterised by non-mechanical control linkages, e.g. fluid control linkages or by control linkages with power drive or assistance
    • F02D11/10Arrangements for, or adaptations to, non-automatic engine control initiation means, e.g. operator initiated characterised by non-mechanical control linkages, e.g. fluid control linkages or by control linkages with power drive or assistance of the electric type
    • F02D11/105Arrangements for, or adaptations to, non-automatic engine control initiation means, e.g. operator initiated characterised by non-mechanical control linkages, e.g. fluid control linkages or by control linkages with power drive or assistance of the electric type characterised by the function converting demand to actuation, e.g. a map indicating relations between an accelerator pedal position and throttle valve opening or target engine torque
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D29/00Controlling engines, such controlling being peculiar to the devices driven thereby, the devices being other than parts or accessories essential to engine operation, e.g. controlling of engines by signals external thereto
    • F02D29/02Controlling engines, such controlling being peculiar to the devices driven thereby, the devices being other than parts or accessories essential to engine operation, e.g. controlling of engines by signals external thereto peculiar to engines driving vehicles; peculiar to engines driving variable pitch propellers
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60WCONJOINT 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
    • B60W2520/00Input parameters relating to overall vehicle dynamics
    • B60W2520/10Longitudinal speed
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60WCONJOINT 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
    • B60W2520/00Input parameters relating to overall vehicle dynamics
    • B60W2520/10Longitudinal speed
    • B60W2520/105Longitudinal acceleration
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D2250/00Engine control related to specific problems or objectives
    • F02D2250/18Control of the engine output torque

Abstract

The fuel-saving control method for the variable-speed cruising of the truck is characterized by comprising the following steps of: s1: the driver operates the shift cruise function, and sets the target cruise vehicle speed to perform the following operations S2, S3, S4, S5, S6, S7, and S8. S2: and judging the vehicle posture in real time. S3: the vehicle cruising speed interval is set. S4: vehicle intervention control, S5: and adjusting and controlling the cruising speed. S6: and (4) performing override control. S7: and (4) cruise exit control. S8: and (4) cruise recovery control. The invention has the following beneficial effects: the real-time attitude information of the vehicle can be accurately and reliably obtained; the cruise control method can avoid frequently triggering cruise allowable upper and lower threshold speed points, and reduce the probability of cruise failure; the driving safety and the safety of the whole vehicle parts can be ensured; the fuel consumption can be saved, and the working strength of a braking system is reduced; in the cruising process of the vehicle, frequent torque change of the engine is avoided, the average combustion efficiency of the engine is improved, the fuel consumption is saved, and the emission is reduced.

Description

Fuel-saving control method for truck speed change cruise
Technical Field
The invention belongs to the field of automobile electric control, and particularly relates to a variable-speed cruise oil-saving control method applied to a truck.
Background
A Cruise Control System (CCS), also called a Cruise Control System, an automatic driving System, and the like. After the system is operated, a driver can set the speed, and the set speed can be kept to run at a constant speed without stepping on an accelerator pedal. By using the system, a driver does not need to control an accelerator pedal any more, so that the fatigue feeling of the driver caused by long-time driving can be relieved, and the speed change caused by bad driving habits can be reduced, so that the automobile runs more economically. In a traditional engine automobile, after a constant-speed cruise system is started, the oil supply amount of an engine is controlled by a computer system, and the oil supply amount can be continuously adjusted according to the current automobile speed, the set automobile speed and the automobile running resistance, so that the automobile can run at a constant speed at the set automobile speed. In the constant-speed cruising process, a driver can press down an accelerator pedal to increase the oil supply of an engine so as to accelerate the vehicle to conveniently accelerate and overtake the vehicle, and the vehicle returns to the cruising speed after the accelerator pedal is released.
As an important production material of national economy, trucks are increasingly paid more attention to safety, economy and comfort in all social circles. Constant speed cruise systems are increasingly popular with drivers as one of the important configurations to improve truck ride comfort and safety.
The traditional constant-speed cruising system of the truck has higher cruising failure probability in the actual use process, and one condition is that when the resistance power exceeds the engine power in the driving process of the vehicle, such as uphill, the vehicle speed is reduced, the lower limit value of the constant-speed cruising speed or the engine speed is triggered to enter a low-torque area, and the cruising system exits; in the other situation, during the running process of the vehicle, when the vehicle descends a slope, the controllable auxiliary braking force of the vehicle is not enough to maintain the vehicle speed, the vehicle speed is increased continuously, the upper limit value of the vehicle speed of the constant-speed cruise is triggered or exceeds the safe rotating speed value of the engine, and the cruise system is quitted.
The traditional constant-speed cruise system of the truck aims at maintaining the speed of the truck, and the engine and the brake system are frequently controlled in the working process of the cruise system, the torque of the engine is frequently increased and decreased, meanwhile, the brake system is frequently involved, the brake energy loss is more, and the fuel economy of the whole truck cannot be considered.
Aiming at the conditions of low cruising success rate, poor fuel economy and the like of the current constant-speed cruising of a truck, the cruising control method which can reduce the labor intensity of a driver, improve the cruising success rate and simultaneously give consideration to the fuel economy of the whole truck is urgently needed.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides the fuel-saving control method for the variable-speed cruising of the truck, which can be realized in a vehicle controller or an engine management system, has clear control method, outstanding fuel-saving effect, stability and reliability, and can continuously adjust the cruising speed according to the vehicle posture in the cruising process of the truck, improve the cruising success rate, improve the fuel economy of the whole truck and reduce the working intensity of drivers and passengers. In order to realize the purpose, the invention adopts the following technical scheme:
a fuel-saving control method for a truck during variable speed cruising comprises the following steps:
s1: the driver operates the cruise control handle, enters the speed change cruise function, and executes the following operations of S2, S3, S4, S5, S6, S7 and S8 after setting the target cruise speed;
s2: the real-time judgment of the vehicle posture specifically comprises the following steps:
s21: one method is to directly obtain the vehicle attitude using a sensor, which increases hardware costs; the sensors include but are not limited to acceleration sensors and gyroscopes, and other sensors capable of obtaining real-time elevation and depression angles of the vehicle;
s22: one method is to obtain the vehicle attitude according to a vehicle dynamic balance formula, wherein the vehicle dynamic balance formula is as follows:
Ft=Fw+Ff+Fi+Fj (1)
wherein: ft: vehicle driving force
Fw: wind resistance
Ff: rolling resistance
Fi: ramp resistance
Fj: resistance to acceleration
S221: obtaining the total mass of the vehicle under the quasi-steady state working condition of the vehicle, and judging the positive and negative values of the ramp resistance; taking two moments when the vehicle speed change is less than 1km/h, the driving distance is less than 100m, the engine output torque and the vehicle acceleration change greatly, assuming that the vehicle speeds at the two moments are equal, namely the rolling resistance and the wind resistance are equal, assuming that the road slopes at the two moments are equal, namely the ramp resistance is equal, and at this moment, the equal-sign two sides of the vehicle power balance formula at the two moments are differed to obtain the following formula:
Ft1-Ft2=Fj1-Fj2 (2)
wherein: ft1、Ft2: vehicle driving force at time 1, 2
Fj1、Fj2: vehicle acceleration resistance at time 1, 2
In addition:
Fj=ma (3)
wherein: m: total mass of the whole vehicle
a: acceleration of the whole vehicle is obtained by differentiating the speed of the vehicle or the speed of the engine
Namely:
wherein: a is1、a2: acceleration of whole vehicle at time 1 and time 2
S222: calculating the resistance power of the vehicle on the windless straight road under the set cruising speed in real time, and obtaining the resistance power by multiplying the equal sign two sides of a formula (1) by the vehicle speed:
Pv0=Fwv+Ffv (5)
wherein: v: current speed per hour of vehicle
Pvo: resistance power of vehicle under windless straight road at vehicle speed v
S223: the method comprises the following steps of calculating the current vehicle speed change trend in real time, differentiating the real-time vehicle speed to obtain a differential value, namely vehicle acceleration, determining the change trend of the vehicle speed through the positive and negative of the vehicle acceleration, wherein the positive value indicates that the vehicle is in an acceleration state, and the negative value indicates that the vehicle is in a deceleration state, and simultaneously obtaining the acceleration resistance of the vehicle:
Fj0=ma0 (6)
wherein: a is0: current vehicle acceleration
S224: calculating the output power of the engine in real time to obtain the driving power for driving the vehicle, wherein the product of the output power of the engine and the efficiency can be obtained by:
wherein: eta: total efficiency of transmission system
T: current driving torque value of engine
n: current speed of engine
S225: calculating according to the vehicle dynamic balance formula in real time, and judging the vehicle pitch angle posture, namely judging whether the vehicle is on an uphill slope or a downhill slope; when the current vehicle acceleration a0When it is zero, proceed PvAnd Pv0Comparison of size when Pv>Pv0Judging that the vehicle is in an uphill road section, otherwise, judging that the vehicle is in a downhill road section; when the current vehicle acceleration a0When the value is not zero:
Pa0=ma0 (8)
wherein: pa0: acceleration power of the current vehicle
Carry out Pv、(Pv+Pa0) When P is greater than or equal tov>(Pv+Pa0) The vehicle is on an uphill road section, otherwise, a downhill road section;
the power is uniformly used for comparing the magnitude, and compared with the driving force, the interference of the speed ratio of the gearbox can be avoided;
s3: the method for setting the vehicle cruising speed interval specifically comprises the following steps:
s31: when the vehicle is in a downhill, allowing the cruise vehicle speed interval to be a vehicle speed value corresponding to the upper limit value of the allowed cruise rotating speed of the engine or a calibrated multiple value of the target cruise vehicle speed to be a set cruise vehicle speed value, reducing the torque of the engine to zero and controlling the vehicle speed to reach the upper limit value of the cruise vehicle speed interval to be a control target, and controlling a main braking system or an auxiliary braking system when the torque of the engine is zero and the vehicle speed exceeds the upper limit value of the cruise vehicle speed interval;
s32: when the vehicle is on an uphill slope, allowing the cruising speed interval to be a speed value corresponding to the lower limit value of the engine allowed cruising speed or a calibrated multiple value of the target cruising speed to be a set cruising speed value, taking the current speed as the feedback of the target cruising speed control to perform quasi-steady state adjustment of the engine torque, judging whether the current speed exceeds the cruising speed interval when the engine torque is increased to an external characteristic value set by the current speed, if so, judging that the cruising is failed, otherwise, keeping cruising running;
s33: when the vehicle runs on a straight road, the engine performs steady-state torque negative feedback control by taking the target cruise speed as a target, and the process comprises that the CAN bus performs variable speed cruise reminding interaction with an instrument or other terminals of the vehicle;
s34: in the process of variable speed cruising, a driver is reminded in the forms of sounds, indicator lights and the like corresponding to the difference value between the target cruising speed and the current speed and the set speed, and an execution unit of the fuel-saving control method for the truck variable speed cruising is communicated with an interpersonal interaction interface including but not limited to an instrument through a CAN bus;
s4: the whole vehicle intervention control is different from a conventional cruise system which only carries out PID torque control on an engine, and the whole vehicle intervention control comprises but not limited to engine control and brake system control, and also comprises transmission system control.
S41: the engine control is characterized in that a quasi-steady-state fuel-saving torque control method is adopted, including but not limited to torque control on an engine by using TSC1 messages in CAN bus standard SAE-J1939, throttle request control on the engine by using a simulated throttle pedal signal, quasi-steady-state control on the engine, torque change rate is obtained according to a calibrated three-dimensional curve which changes along with the engine rotating speed and the engine torque, and the driving force adjustment of the whole vehicle is realized by adding and subtracting the engine torque to control the vehicle speed;
s42: the main brake system control comprises but not limited to brake force control of the electronic brake system through a CAN bus response message, and CAN also comprise a brake solenoid valve for directly controlling the pressure of a brake pipeline so as to control the brake force of the whole vehicle, and the vehicle speed is reduced or maintained through the main brake force control;
s43: the auxiliary braking system control comprises but is not limited to braking force control on the whole vehicle auxiliary systems such as engine braking, exhaust braking and a hydraulic retarder through CAN bus or signal control, and the vehicle speed is reduced or maintained through the auxiliary braking system control;
s44, controlling a transmission system, namely, requesting a target gear from the automatic gearbox in a gear shifting and cruising process by using a mode including but not limited to a CAN bus or signal control so as to realize the speed ratio adjustment of the transmission system for a vehicle matched with the automatic gearbox;
s5: cruise vehicle speed adjustment control, i.e. during the vehicle speed change cruise, the driver can operate the cruise handle to realize cruise set vehicle speed adjustment, and the cruise set vehicle speed is adjusted correspondingly under the step S3;
s6: the method comprises the following steps of performing override control, namely adopting driving characteristic required torque to control an engine when the driving characteristic required torque exceeds cruise engine control torque after a driver steps on an accelerator pedal in the variable speed cruise working process, and otherwise using a cruise engine torque control value to control the engine;
s7: a cruise exit control that exits cruise when events including, but not limited to, a trigger clutch signal, a gear in neutral, a trigger brake signal, a trigger cruise exit signal, an engine malfunction, a transmission malfunction;
s8: and (4) cruise recovery control, wherein after the cruise system is started and withdrawn, the driver does not stop the engine and continues driving, the driver operates the cruise handle to recover the cruise function, and the set cruise speed is the set cruise speed value of the last cruise function.
The general procedure of the invention is described in detail below, with reference to FIG. 1:
the speed-changing cruise control method is basically the same as that of the conventional constant-speed cruise, and comprises cruise entering judgment, cruise recovery judgment, override control, exit control, power system control and the like; the differences are the cruise set speed, the engine control and the brake system in the cruise process, and the cruise set speed, the engine control and the brake system of the invention are explained as follows:
the cruise set vehicle speed is set to the cruise vehicle speed section during a shift cruise, and an allowable vehicle speed is determined based on the vehicle attitude, the engine speed, the cruise set vehicle speed, and the like.
The speed-changing cruise control method is basically the same as that of the conventional constant-speed cruise, and comprises cruise entering judgment, cruise recovery judgment, override control, exit control, power system control and the like; the differences are the cruise set speed, the engine control and the brake system in the cruise process, and the cruise set speed, the engine control and the brake system of the invention are explained as follows:
the cruise set vehicle speed is set to the cruise vehicle speed section during a shift cruise, and an allowable vehicle speed is determined based on the vehicle attitude, the engine speed, the cruise set vehicle speed, and the like.
The engine control adopts an engine quasi-steady-state fuel-saving torque control method, reduces the transient working condition of the engine, and avoids combustion deterioration caused by frequent and large-amplitude torque addition and subtraction.
The control of the braking system is an electronic braking system control and an auxiliary braking mode including engine braking, a hydraulic retarder, exhaust braking and the like, and the intervention of the current running speed is realized through active control of the braking system.
In addition, the fuel-saving control method for the speed-changing cruise of the truck is characterized by comprising the steps of controlling the target gear of a gearbox and changing the speed ratio of a transmission system on a matched automatic-gear vehicle so as to intervene the running speed of the whole vehicle and the rotating speed of an engine.
The shift cruise control procedure of the present invention is described in detail below, with reference to FIG. 2:
firstly, judging the vehicle attitude by using a whole vehicle dynamic balance formula:
when the vehicle runs on a straight road, the cruise system controls the quasi-steady-state torque output of the engine by taking the difference value between the current vehicle speed and the cruise set vehicle speed as negative feedback, and the current vehicle speed of the vehicle runs along with the cruise set vehicle speed;
when the vehicle runs on an uphill road, judging the vehicle speed variation trend of the vehicle by referring to the current torque of the engine, and when the cruise set vehicle speed is enough to be maintained, maintaining the current torque of the engine unchanged; when the set vehicle speed is not enough to be maintained, the engine torque is stably increased, whether the engine torque exceeds the external characteristics of the engine or not is judged, when the engine torque does not exceed the external characteristics of the engine, the vehicle is maintained to run by taking the increased engine torque value as the control torque, when the engine torque exceeds the external characteristics of the engine, the engine maximum torque is controlled, whether the vehicle speed exceeds the lower limit value of the cruise vehicle speed interval or not is continuously judged, the cruise is failed and quit is carried out if the vehicle speed exceeds the lower limit value of the cruise vehicle speed;
when the vehicle runs on a downhill road, controlling the vehicle speed by taking the upper limit value of the cruise vehicle speed interval as a target, and when the current vehicle speed is equal to the upper limit value of the cruise vehicle speed interval, maintaining the current engine torque or brake system control unchanged; when the current speed of the vehicle is lower than the upper limit value of the cruise speed interval, judging the speed change trend, when the vehicle is in the deceleration process, judging whether the current speed of the vehicle exceeds the lower limit of the cruise speed interval, if so, stably increasing the torque of the engine, if not, maintaining the current torque of the engine, when the vehicle is in the acceleration stage, stably decreasing the torque of the engine, if the engine reaches a zero torque output point, and if so, increasing the braking torque of a braking system, otherwise, performing constant torque output control on the engine.
The invention has the following beneficial effects: 1. the vehicle dynamics analysis or related sensors are carried out according to the dynamics classical formula, so that the real-time attitude information of the vehicle can be accurately and reliably obtained; 2. in the cruising process of the vehicle, the cruising speed can realize the change of a larger interval, thereby avoiding frequently triggering cruising allowable upper and lower threshold speed points and reducing the cruising failure probability; 3. in the cruising process of the vehicle, the cruising speed range is comprehensively determined according to the actual road condition of the vehicle, the working interval of an engine, the set cruising speed value and the like, so that the driving safety and the safety of parts of the whole vehicle are ensured; 4. in the cruising process of the vehicle, when the vehicle goes down a slope, the vehicle is allowed to reach a higher speed, the kinetic energy of the vehicle is stored, and when the vehicle goes up the slope, the kinetic energy of the vehicle is converted into the gravitational potential energy of the vehicle, so that the fuel consumption is saved, and meanwhile, the working strength of a braking system is reduced; 5. during the cruising process of the vehicle, the engine is controlled in a quasi-steady state, the transient working condition of the engine is reduced, the frequent torque change of the engine is avoided, the average combustion efficiency of the engine is improved, the fuel consumption is saved, and the emission is reduced.
Description of the drawings:
FIG. 1 is a general process flow diagram of the present invention;
FIG. 2 is a flowchart of a variable speed cruise control process.
The specific implementation mode is as follows:
as shown in fig. 1 and 2:
a fuel-saving control method for a truck during variable speed cruising comprises the following steps:
s1: the driver operates the cruise control handle, enters the speed change cruise function, and executes the following operations of S2, S3, S4, S5, S6, S7 and S8 after setting the target cruise speed;
s2: the real-time judgment of the vehicle posture specifically comprises the following steps:
s21: one method is to directly obtain the vehicle attitude using a sensor, which increases hardware costs; the sensors include but are not limited to acceleration sensors and gyroscopes, and other sensors capable of obtaining real-time elevation and depression angles of the vehicle;
s22: one method is to obtain the vehicle attitude according to a vehicle dynamic balance formula, wherein the vehicle dynamic balance formula is as follows:
Ft=Fw+Ff+Fi+Fj (1)
wherein: ft: vehicle driving force
Fw: wind resistance
Ff: rolling resistance
Fi: ramp resistance
Fj: resistance to acceleration
S221: obtaining the total mass of the vehicle under the quasi-steady state working condition of the vehicle, and judging the positive and negative values of the ramp resistance; taking two moments when the vehicle speed change is less than 1km/h, the driving distance is less than 100m, the engine output torque and the vehicle acceleration change greatly, assuming that the vehicle speeds at the two moments are equal, namely the rolling resistance and the wind resistance are equal, assuming that the road slopes at the two moments are equal, namely the ramp resistance is equal, and at this moment, the equal-sign two sides of the vehicle power balance formula at the two moments are differed to obtain the following formula:
Ft1-Ft2=Fj1-Fj2 (2)
wherein: ft1、Ft2: vehicle driving force at time 1, 2
Fj1、Fj2: vehicle acceleration resistance at time 1, 2
In addition:
Fj=ma (3)
wherein: m: total mass of the whole vehicle
a: acceleration of the whole vehicle is obtained by differentiating the speed of the vehicle or the speed of the engine
Namely:
wherein: a is1、a2: acceleration of whole vehicle at time 1 and time 2
S222: calculating the resistance power of the vehicle on the windless straight road under the set cruising speed in real time, and obtaining the resistance power by multiplying the equal sign two sides of a formula (1) by the vehicle speed:
Pv0=Fwv+Ffv (5)
wherein: v: current speed per hour of vehicle
Pvo: resistance power of vehicle under windless straight road at vehicle speed v
S223: the method comprises the following steps of calculating the current vehicle speed change trend in real time, differentiating the real-time vehicle speed to obtain a differential value, namely vehicle acceleration, determining the change trend of the vehicle speed through the positive and negative of the vehicle acceleration, wherein the positive value indicates that the vehicle is in an acceleration state, and the negative value indicates that the vehicle is in a deceleration state, and simultaneously obtaining the acceleration resistance of the vehicle:
Fj0=ma0 (6)
wherein: a is0: current vehicle acceleration
S224: calculating the output power of the engine in real time to obtain the driving power for driving the vehicle, wherein the product of the output power of the engine and the efficiency can be obtained by:
wherein: eta: total efficiency of transmission system
T: current driving torque value of engine
n: current speed of engine
S225: calculating according to the vehicle dynamic balance formula in real time, and judging the vehicle pitch angle posture, namely judging whether the vehicle is on an uphill slope or a downhill slope; when the current vehicle acceleration a0When it is zero, proceed PvAnd Pv0Comparison of size when Pv>Pv0Judging that the vehicle is in an uphill road section, otherwise, judging that the vehicle is in a downhill road section; when the current vehicle acceleration a0When the value is not zero:
Pa0=ma0 (8)
wherein: pa0: acceleration power of the current vehicle
Carry out Pv、(Pv+Pa0) When P is greater than or equal tov>(Pv+Pa0) The vehicle is on an uphill road section, otherwise, a downhill road section;
the power is uniformly used for comparing the magnitude, and compared with the driving force, the interference of the speed ratio of the gearbox can be avoided;
s3: the method for setting the vehicle cruising speed interval specifically comprises the following steps:
s31: when the vehicle is in a downhill, allowing the cruise vehicle speed interval to be a vehicle speed value corresponding to the upper limit value of the allowed cruise rotating speed of the engine or a calibrated multiple value of the target cruise vehicle speed to be a set cruise vehicle speed value, reducing the torque of the engine to zero and controlling the vehicle speed to reach the upper limit value of the cruise vehicle speed interval to be a control target, and controlling a main braking system or an auxiliary braking system when the torque of the engine is zero and the vehicle speed exceeds the upper limit value of the cruise vehicle speed interval;
s32: when the vehicle is on an uphill slope, allowing the cruising speed interval to be a speed value corresponding to the lower limit value of the engine allowed cruising speed or a calibrated multiple value of the target cruising speed to be a set cruising speed value, taking the current speed as the feedback of the target cruising speed control to perform quasi-steady state adjustment of the engine torque, judging whether the current speed exceeds the cruising speed interval when the engine torque is increased to an external characteristic value set by the current speed, if so, judging that the cruising is failed, otherwise, keeping cruising running;
s33: when the vehicle runs on a straight road, the engine performs steady-state torque negative feedback control by taking the target cruise speed as a target, and the process comprises that the CAN bus performs variable speed cruise reminding interaction with an instrument or other terminals of the vehicle;
s34: in the process of variable speed cruising, a driver is reminded in the forms of sounds, indicator lights and the like corresponding to the difference value between the target cruising speed and the current speed and the set speed, and an execution unit of the fuel-saving control method for the truck variable speed cruising is communicated with an interpersonal interaction interface including but not limited to an instrument through a CAN bus;
s4: the whole vehicle intervention control is different from a conventional cruise system which only carries out PID torque control on an engine, and the whole vehicle intervention control comprises but not limited to engine control and brake system control, and also comprises transmission system control.
S41: the engine control is characterized in that a quasi-steady-state fuel-saving torque control method is adopted, including but not limited to torque control on an engine by using TSC1 messages in CAN bus standard SAE-J1939, throttle request control on the engine by using a simulated throttle pedal signal, quasi-steady-state control on the engine, torque change rate is obtained according to a calibrated three-dimensional curve which changes along with the engine rotating speed and the engine torque, and the driving force adjustment of the whole vehicle is realized by adding and subtracting the engine torque to control the vehicle speed;
s42: the main brake system control comprises but not limited to brake force control of the electronic brake system through a CAN bus response message, and CAN also comprise a brake solenoid valve for directly controlling the pressure of a brake pipeline so as to control the brake force of the whole vehicle, and the vehicle speed is reduced or maintained through the main brake force control;
s43: the auxiliary braking system control comprises but is not limited to braking force control on the whole vehicle auxiliary systems such as engine braking, exhaust braking and a hydraulic retarder through CAN bus or signal control, and the vehicle speed is reduced or maintained through the auxiliary braking system control;
s44, controlling a transmission system, namely, requesting a target gear from the automatic gearbox in a gear shifting and cruising process by using a mode including but not limited to a CAN bus or signal control so as to realize the speed ratio adjustment of the transmission system for a vehicle matched with the automatic gearbox;
s5: cruise vehicle speed adjustment control, i.e. during the vehicle speed change cruise, the driver can operate the cruise handle to realize cruise set vehicle speed adjustment, and the cruise set vehicle speed is adjusted correspondingly under the step S3;
s6: the method comprises the following steps of performing override control, namely adopting driving characteristic required torque to control an engine when the driving characteristic required torque exceeds cruise engine control torque after a driver steps on an accelerator pedal in the variable speed cruise working process, and otherwise using a cruise engine torque control value to control the engine;
s7: a cruise exit control that exits cruise when events including, but not limited to, a trigger clutch signal, a gear in neutral, a trigger brake signal, a trigger cruise exit signal, an engine malfunction, a transmission malfunction;
s8: and (4) cruise recovery control, wherein after the cruise system is started and withdrawn, the driver does not stop the engine and continues driving, the driver operates the cruise handle to recover the cruise function, and the set cruise speed is the set cruise speed value of the last cruise function.
The following is a detailed description of the general procedure of the invention:
the speed-changing cruise control method is basically the same as that of the conventional constant-speed cruise, and comprises cruise entering judgment, cruise recovery judgment, override control, exit control, power system control and the like; the differences are the cruise set speed, the engine control and the brake system in the cruise process, and the cruise set speed, the engine control and the brake system of the invention are explained as follows:
the cruise set vehicle speed is set to the cruise vehicle speed section during a shift cruise, and an allowable vehicle speed is determined based on the vehicle attitude, the engine speed, the cruise set vehicle speed, and the like.
The speed-changing cruise control method is basically the same as that of the conventional constant-speed cruise, and comprises cruise entering judgment, cruise recovery judgment, override control, exit control, power system control and the like; the differences are the cruise set speed, the engine control and the brake system in the cruise process, and the cruise set speed, the engine control and the brake system of the invention are explained as follows:
the cruise set vehicle speed is set to the cruise vehicle speed section during a shift cruise, and an allowable vehicle speed is determined based on the vehicle attitude, the engine speed, the cruise set vehicle speed, and the like.
The engine control adopts an engine quasi-steady-state fuel-saving torque control method, reduces the transient working condition of the engine, and avoids combustion deterioration caused by frequent and large-amplitude torque addition and subtraction.
The control of the braking system is an electronic braking system control and an auxiliary braking mode including engine braking, a hydraulic retarder, exhaust braking and the like, and the intervention of the current running speed is realized through active control of the braking system.
In addition, the fuel-saving control method for the speed-changing cruise of the truck is characterized by comprising the steps of controlling the target gear of a gearbox and changing the speed ratio of a transmission system on a matched automatic-gear vehicle so as to intervene the running speed of the whole vehicle and the rotating speed of an engine.
The shift cruise control procedure of the present invention is explained in detail below:
firstly, judging the vehicle attitude by using a whole vehicle dynamic balance formula:
when the vehicle runs on a straight road, the cruise system controls the quasi-steady-state torque output of the engine by taking the difference value between the current vehicle speed and the cruise set vehicle speed as negative feedback, and the current vehicle speed of the vehicle runs along with the cruise set vehicle speed;
when the vehicle runs on an uphill road, judging the vehicle speed variation trend of the vehicle by referring to the current torque of the engine, and when the cruise set vehicle speed is enough to be maintained, maintaining the current torque of the engine unchanged; when the set vehicle speed is not enough to be maintained, the engine torque is stably increased, whether the engine torque exceeds the external characteristics of the engine or not is judged, when the engine torque does not exceed the external characteristics of the engine, the vehicle is maintained to run by taking the increased engine torque value as the control torque, when the engine torque exceeds the external characteristics of the engine, the engine maximum torque is controlled, whether the vehicle speed exceeds the lower limit value of the cruise vehicle speed interval or not is continuously judged, the cruise is failed and quit is carried out if the vehicle speed exceeds the lower limit value of the cruise vehicle speed;
when the vehicle runs on a downhill road, controlling the vehicle speed by taking the upper limit value of the cruise vehicle speed interval as a target, and when the current vehicle speed is equal to the upper limit value of the cruise vehicle speed interval, maintaining the current engine torque or brake system control unchanged; when the current speed of the vehicle is lower than the upper limit value of the cruise speed interval, judging the speed change trend, when the vehicle is in the deceleration process, judging whether the current speed of the vehicle exceeds the lower limit of the cruise speed interval, if so, stably increasing the torque of the engine, if not, maintaining the current torque of the engine, when the vehicle is in the acceleration stage, stably decreasing the torque of the engine, if the engine reaches a zero torque output point, and if so, increasing the braking torque of a braking system, otherwise, performing constant torque output control on the engine.

Claims (10)

1. The fuel-saving control method for the variable-speed cruising of the truck is characterized by comprising the following steps of:
s1: the driver operates the shift cruise function, and after setting the target cruise vehicle speed, the following operations of S2, S3, S4, S5, S6, S7 and S8 are executed;
s2: the real-time judgment of the vehicle posture specifically comprises the following steps:
s21: directly obtaining the vehicle attitude using a sensor;
s22: obtaining the vehicle attitude according to a vehicle dynamic balance formula, comprising the steps of:
s221: obtaining the total mass of the vehicle under the quasi-steady state working condition of the vehicle;
s222: calculating resistance power of the vehicle on a windless straight road at a set cruising speed in real time;
s223: calculating the current vehicle speed change trend in real time;
s224: calculating the output power of the engine in real time;
s225: calculating a real-time whole vehicle dynamic balance formula, and judging whether the vehicle is an uphill slope or a downhill slope;
s3: the method for setting the vehicle cruising speed interval specifically comprises the following steps:
s31: when the vehicle is in a downhill, the allowed vehicle speed is a vehicle speed value corresponding to the upper limit value of the allowed cruising rotating speed of the engine or a calibrated multiple value of the set cruising vehicle speed value to the set cruising vehicle speed value;
s32: when the vehicle is on an uphill slope, the allowable vehicle speed is a vehicle speed value corresponding to the lower limit value of the allowable cruising speed of the engine or a calibrated multiple value of the set cruising speed to the set cruising speed value;
s33: when the vehicle runs on a straight road, the engine takes the target cruise speed as a target to carry out steady-state torque negative feedback control;
s34: in the variable speed cruising process, a driver is reminded in the forms of sound, indicator lights and the like corresponding to the difference value between the current vehicle speed and the set vehicle speed;
s4: the whole vehicle intervention control specifically comprises:
s41: controlling the fuel-saving torque of the engine;
s42: main brake system control;
s43: auxiliary brake system control;
s44: controlling a transmission system;
s5: cruise vehicle speed adjustment control, i.e. during the vehicle speed change cruise, the driver can operate the cruise handle to realize the cruise set vehicle speed adjustment, and the cruise set vehicle speed is correspondingly adjusted under the step S3;
s6: the method comprises the following steps of performing override control, namely adopting driving characteristic required torque to control an engine when the driving characteristic required torque exceeds cruise engine control torque after a driver steps on an accelerator pedal in the variable speed cruise working process, and otherwise using a cruise engine torque control value to control the engine;
s7: a cruise exit control that exits cruise when events including, but not limited to, a trigger clutch signal, a gear in neutral, a trigger brake signal, a trigger cruise exit signal, an engine malfunction, a transmission malfunction;
s8: and (4) cruise recovery control, wherein after the cruise system is started and withdrawn, the driver does not stop the engine and continues driving, the driver operates the cruise handle to recover the cruise function, and the set cruise speed is the set cruise speed value of the last cruise function.
2. The fuel-saving control method for the variable-speed cruise of the truck as claimed in claim 1, wherein in said step S21, the sensors used comprise an acceleration sensor and a gyroscope.
3. The fuel-saving control method for the variable-speed cruise of the truck as claimed in claim 1, characterized in that: the engine control adopts a quasi-steady-state fuel-saving torque control method to collect message data on a CAN bus.
4. The fuel-saving control method for the speed-changing cruise of the truck as claimed in claim 1, wherein in said step S31, the upper limit value of the allowed cruise rotation speed of the engine is the calibration value of the safe rotation speed of the engine; in the calibration multiple value of the set cruise speed value, the multiple value is obtained according to a multiple curve changed along with the set cruise speed value.
5. The fuel-saving control method for the variable speed cruise of the truck as claimed in claim 1, wherein in step S32, the lower limit value of the allowed cruise rotation speed of the engine is preferably the idling speed of the engine; in the calibration multiple value of the set cruise speed value, the multiple value is obtained according to a calibrated multiple curve changing along with the set cruise speed value.
6. The fuel-saving control method for the variable-speed cruise of the truck as claimed in claim 1, wherein in step S33, a CAN bus is used to interact with a meter or other terminals of the vehicle for the variable-speed cruise reminding.
7. The fuel-saving control method for the truck speed-changing cruise according to claim 1, wherein in step S41, the TSC1 is used to perform torque control on the engine, the simulated accelerator pedal signal is used to perform accelerator request control on the engine, quasi-steady state control is performed on the engine, and the torque change rate is obtained according to a calibrated three-dimensional curve varying with the engine speed and the engine torque.
8. The fuel-saving control method for the variable-speed cruise of the truck as claimed in claim 1, wherein said step S42 includes controlling the electric braking system of the truck by using a message.
9. The fuel-saving control method for the variable speed cruise of the truck as claimed in claim 1, wherein in said step S43, said auxiliary braking system comprises engine brake, exhaust brake, and hydraulic retarder.
10. The fuel-saving control method for the variable speed cruise of the truck as claimed in claim 1, wherein in said step S44, said transmission system control includes transmission system target gear and clutch engagement state control.
CN201910358195.XA 2019-04-30 2019-04-30 Fuel-saving control method for truck speed change cruise Active CN110155051B (en)

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