CN109969161B - Vehicle starting method and device - Google Patents

Vehicle starting method and device Download PDF

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Publication number
CN109969161B
CN109969161B CN201711448129.9A CN201711448129A CN109969161B CN 109969161 B CN109969161 B CN 109969161B CN 201711448129 A CN201711448129 A CN 201711448129A CN 109969161 B CN109969161 B CN 109969161B
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vehicle
state
automobile
starting
control unit
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CN109969161A (en
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周铁
马龙兴
何介夫
刘天培
曾迁
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Great Wall Motor Co Ltd
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Great Wall Motor Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00—Conjoint control of vehicle sub-units of different type or different function
    • B60W10/04—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units
    • B60W10/08—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units including control of electric propulsion units, e.g. motors or generators
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00—Conjoint control of vehicle sub-units of different type or different function
    • B60W10/119—Conjoint control of vehicle sub-units of different type or different function including control of all-wheel-driveline means, e.g. transfer gears or clutches for dividing torque between front and rear axle
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W20/00—Control systems specially adapted for hybrid vehicles
    • B60W20/10—Controlling the power contribution of each of the prime movers to meet required power demand
    • B60W20/12—Controlling the power contribution of each of the prime movers to meet required power demand using control strategies taking into account route information
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
    • B60W30/18—Propelling the vehicle
    • B60W30/18009—Propelling the vehicle related to particular drive situations
    • B60W30/18027—Drive off, accelerating from standstill
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2510/00—Input parameters relating to a particular sub-units
    • B60W2510/08—Electric propulsion units
    • B60W2510/081—Speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2510/00—Input parameters relating to a particular sub-units
    • B60W2510/08—Electric propulsion units
    • B60W2510/083—Torque
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2520/00—Input parameters relating to overall vehicle dynamics
    • B60W2520/10—Longitudinal speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2540/00—Input parameters relating to occupants
    • B60W2540/10—Accelerator pedal position
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2540/00—Input parameters relating to occupants
    • B60W2540/16—Ratio selector position
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2710/00—Output or target parameters relating to a particular sub-units
    • B60W2710/08—Electric propulsion units
    • B60W2710/083—Torque

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Automation & Control Theory (AREA)
  • Hybrid Electric Vehicles (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)

Abstract

The invention provides a vehicle starting method and a vehicle starting device, wherein the method is applied to a hybrid electric vehicle, the vehicle comprises a rear axle motor, and the method comprises the following steps: when the sand driving function of the automobile is detected to be started, the current speed of the automobile is obtained; judging whether the automobile is in a starting state or not according to the current speed; if the automobile is in a starting state, judging whether the rear axle motor is in a locked-rotor state; if the rear axle motor is in a locked-rotor state, executing a preset control strategy corresponding to the sand starting function; the preset control strategy corresponding to the sand starting function comprises the following steps: and controlling the rear axle motor to output torque in a mode of increasing a preset torque gradient, and controlling the vehicle body stability control unit (ESP) to increase a rear drive slip rate threshold. The problem of among the prior art through the control hybrid vehicle of traditional mode four-wheel drive mode when starting on the sand ground, because motor torque output is abnormal and then cause the potential safety hazard of burning out the motor is solved.

Description

Vehicle starting method and device
Technical Field
The invention relates to the field of automobiles, in particular to the field of hybrid electric vehicles, and discloses a vehicle starting method and a vehicle starting device.
Background
In order to adapt to the national vehicle emission reduction standard, electric vehicles and hybrid electric vehicles become the main development trend of future vehicles. In a conventional driving mode of a hybrid electric vehicle, the power of a front shaft is derived from a traditional engine and a Starter generator BSG (belt Starter generator) driven by a belt of the traditional engine, a rear wheel is driven by a motor to run, the power of the motor is derived from a high-voltage battery pack, and the battery pack can be charged by an external power supply through a vehicle-mounted charger and can also be used for generating power and recovering energy for energy storage by the BSG during running. In general, the hybrid electric four-wheel drive system with the driving mode can meet the driving requirements under certain off-road conditions, such as snowfields, mud fields and sand fields. The running resistance of the sand in the three road conditions, particularly the soft sand, has high power demand on the vehicle, and the vehicle can be stably started in the sand by accuracy.
In the prior art, most vehicles carrying off-road working conditions are traditional mechanical four-wheel drives, reasonable output of power can be realized through a matched engine and a well-matched transmission system, meanwhile, power distribution of 0% -50% of a front shaft and 50% -100% of a rear shaft is realized by means of mechanical four-wheel drive control, but for electric four-wheel drive control of a hybrid vehicle, the control principle of the mechanical four-wheel drive cannot be used, and particularly, when the existing hybrid four-wheel drive control hybrid vehicle is used for starting in a sand ground mode, the motor torque output is abnormal due to overlarge driving resistance, so that the motor of the rear shaft is blocked, the vehicle fails to start in the sand, and the potential safety hazard of the motor is burnt.
Disclosure of Invention
In view of the above, in the prior art, the starting control of the hybrid electric vehicle on the sandy ground is realized through the electric four-wheel drive control of the hybrid electric vehicle, so that the starting of the vehicle on the sandy ground fails, and the potential safety hazard of burning the motor is caused.
In order to solve the above problems, the technical solution of the present invention is realized as follows:
a vehicle take-off method applied to a hybrid vehicle, the vehicle including a rear axle motor, the method comprising: when the sand driving function of the automobile is detected to be started, the current speed of the automobile is obtained; judging whether the automobile is in a starting state or not according to the current speed; if the automobile is in a starting state, judging whether the rear axle motor is in a locked-rotor state; if the rear axle motor is in a locked-rotor state, executing a preset control strategy corresponding to the sand starting function; the preset control strategy corresponding to the sand starting function comprises the following steps: and controlling the rear axle motor to output torque in a mode of increasing a preset torque gradient, and controlling the vehicle body stability control unit (ESP) to increase a rear drive slip rate threshold.
Further, the step of judging whether the automobile is in a starting state or not according to the current speed comprises the following steps: if the current speed is 0, acquiring the current execution gear of the automobile; and if the current execution gear of the automobile is a driving gear, the automobile is in a starting state.
Further, if the automobile is in a starting state, the step of judging whether the rear axle motor is in a locked-rotor state includes: if the automobile is in a starting state, judging whether an accelerator pedal of the automobile is stepped on; if the accelerator pedal of the automobile is stepped on, judging whether the product of the torque of the rear axle motor and the motor rotating speed is 0; and if the product of the torque of the rear axle motor and the rotating speed of the motor is 0, the rear axle motor is in a locked-rotor state.
Further, the method also comprises the following steps: and if the rear axle motor is not in a locked-rotor state, executing a preset control strategy corresponding to the sand driving function, and controlling the driving state of the automobile.
Further, the step of executing a preset control strategy corresponding to the sand driving function and controlling the driving state of the automobile includes:
the hybrid power control unit HCU sends control signals of a preset control strategy corresponding to the sand driving function to an engine control unit EMS, a transmission control unit DCT, a vehicle body stability control unit ESP and a motor control unit MCU respectively; the hybrid power control unit HCU acquires state signals returned by the engine control unit EMS, the transmission control unit DCT, the vehicle body stability control unit ESP and the motor control unit MCU; the hybrid power control unit HCU is combined with the returned state signal and the electric quantity of the rear axle motor to execute a preset control strategy corresponding to the sand driving function; the preset control strategy corresponding to the sand driving function comprises controlling the output of the starting torque and the high-speed torque of the automobile and providing the maximum torque transmission; and calculating and outputting the output torque of the front and rear shafts according to the opening degree of an accelerator pedal.
Compared with the prior art, the vehicle starting method has the following advantages: the method comprises the steps of judging whether a vehicle is in a sand starting working condition or not by monitoring the current operation of a driver and the real-time state of the vehicle, actively adjusting the torque output of a rear axle motor and adjusting the slip rate of a rear wheel when the vehicle is detected to be in the starting state and the rear axle motor has a stalling trend, so as to assist the hybrid electric vehicle to start in the sand. The vehicle has the beneficial effects that the vehicle can start more easily and drive more safely in a sand mode by controlling the output torque of the front and rear shafts (particularly the rear shaft).
Another object of the present invention is to provide a vehicle starting apparatus applied to a hybrid vehicle including a rear axle motor, the apparatus including: the vehicle speed acquisition module is used for acquiring the current vehicle speed of the vehicle when the vehicle is detected to start a sand driving function; the starting state judging module is used for judging whether the automobile is in a starting state or not according to the current speed; the motor state judging module is used for judging whether the rear axle motor is in a locked-rotor state or not if the automobile is in a starting state; the sand starting module is used for executing a preset control strategy corresponding to a sand starting function if the rear axle motor is in a locked-rotor state; the preset control strategy corresponding to the sand starting function comprises the following steps: and controlling the rear axle motor to output torque in a mode of increasing a preset torque gradient, and controlling the vehicle body stability control unit (ESP) to increase a rear drive slip rate threshold.
Further, the starting state judgment module comprises: the gear state acquisition submodule is used for acquiring the current execution gear of the automobile if the current speed is 0; and the starting state acquisition submodule is used for enabling the automobile to be in a starting state if the current execution gear of the automobile is a driving gear.
Further, the sand launching module comprises: the accelerator pedal state acquisition submodule is used for judging whether an accelerator pedal of the automobile is stepped on or not if the automobile is in a starting state; if the accelerator pedal of the automobile is stepped on in the motor state, judging whether the product of the torque of the rear axle motor and the motor rotating speed is 0 or not; and if the product of the torque of the rear axle motor and the rotating speed of the motor is 0, the rear axle motor is in a locked-rotor state.
Further, the method also comprises the following steps: and the sand driving module is used for executing a preset control strategy corresponding to the sand driving function and controlling the running state of the automobile if the rear axle motor is not in a locked-rotor state.
Further, the sand driving module comprises: the control signal sending submodule is used for the hybrid control unit HCU to respectively send control signals of a preset control strategy corresponding to the sand driving function to the engine control unit EMS, the transmission control unit DCT, the vehicle body stability control unit ESP and the motor control unit MCU; the state signal acquisition submodule is used for acquiring state signals returned by the engine control unit EMS, the transmission control unit DCT, the vehicle body stability control unit ESP and the motor control unit MCU by the hybrid control unit HCU; the control strategy execution submodule is used for the hybrid control unit HCU to execute a preset control strategy corresponding to the sand driving function by combining the returned state signal and the electric quantity of the rear axle motor; the preset control strategy corresponding to the sand driving function comprises controlling the output of the starting torque and the high-speed torque of the automobile and providing the maximum torque transmission; and calculating and outputting the output torque of the front and rear shafts according to the opening degree of an accelerator pedal.
Compared with the prior art, the vehicle starting device and the vehicle starting method have the same advantages, and are not repeated herein.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 is a flowchart of a vehicle starting method according to a first embodiment of the present invention;
fig. 2 is a schematic diagram of a vehicle control architecture according to an embodiment of the present invention;
fig. 3 is a flowchart of a vehicle starting method according to a second embodiment of the present invention;
FIG. 4 is a schematic view of a vehicle under load according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of an execution flow of the starting system for a sandy ground according to an embodiment of the present invention;
fig. 6 is a structural block diagram of a vehicle starting device according to a third embodiment of the invention;
fig. 7 is a block diagram of a vehicle starting device according to a third embodiment of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
Example one
Referring to fig. 1, which is a flowchart of a vehicle starting method according to an embodiment of the present invention, the method is applied to a hybrid electric vehicle, where the vehicle includes a rear axle motor, and the method may specifically include the following steps:
step 101, when the sand driving function of the automobile is detected to be started, the current speed of the automobile is obtained.
In the embodiment of the invention, when the whole vehicle control module detects that the sand driving function of the vehicle is in the opening state, the current running speed of the vehicle is obtained through a speed sensor arranged on the vehicle.
IN practical application, as shown IN fig. 2, when the driver selects the sand driving mode IN the off-road mode, the road detection module detects that the current road condition is sand, the sand driving mode switch is turned on, the switch module sends a driving mode switch signal (DrivingMode) to the vehicle body control module BCM (body control module) through the L IN bus, the BCM converts the driving mode switch signal (DrivingMode) into a mode signal (drvdmod) and forwards the mode signal (drvdmod) to the CAN bus, and then the CAN bus forwards the mode signal (drvdmod) to the vehicle control module.
And 102, judging whether the automobile is in a starting state or not according to the current speed.
In the embodiment of the invention, after the current vehicle speed is obtained, whether the current vehicle is in a starting state or not can be judged according to the current vehicle speed and the running state of the vehicle. For example, when the acquired vehicle speed is low and the vehicle is in a running state, the vehicle is in a starting state.
And 103, if the automobile is in a starting state, judging whether the rear axle motor is in a locked-rotor state.
In the embodiment of the invention, a hybrid electric vehicle is generally provided with an engine and a motor as power drive of the vehicle, and under the normal condition, according to the arrangement position of the motor in a power system, the hybrid electric vehicle is divided into P0 (the motor is arranged in a front end gear train of the engine and is coupled with a crankshaft of the engine through a belt), P1 (the motor is arranged at a flywheel end of the engine and is directly coupled with the crankshaft), P2 (the motor is arranged between the engine and a gearbox and controls power transmission through a clutch), P3 (the motor is arranged at the rear end of the gearbox and is coupled with an output shaft), P4 (the motor is arranged at a rear axle and is used as a driving module to output power alone), for a hybrid electric four-wheel drive system of P0+ P4 power configuration, the front axle power is derived from a traditional engine and a starting generator BSG (belt Starter generator), the front axle torque TrAct _ FA is used as the sum of the engine output torque and BSGAGATGATQ, namely TrQCranksQ, the front axle torque TrqF is used as the energy, and is derived from a hybrid electric vehicle running power supply unit, and can be controlled by a hybrid electric vehicle through a hybrid electric vehicle battery pack (hybrid electric vehicle) and a hybrid electric vehicle can be controlled by a hybrid electric vehicle-mounted battery pack, and a hybrid electric vehicle-driven by a hybrid electric vehicle-mounted.
Therefore, in the embodiment of the invention, the hybrid electric four-wheel drive system with the power configuration of P0+ P4 is introduced, the motor is arranged at the rear axle and is used as a drive module to output power, also called as eAD, so that in the sand driving mode, the running state of the rear axle motor is detected at any time, and whether the locked rotation occurs or not is judged.
104, if the rear axle motor is in a locked-rotor state, executing a preset control strategy corresponding to a sand starting function; the preset control strategy corresponding to the sand starting function comprises the following steps: and controlling the rear axle motor to output torque in a mode of increasing a preset torque gradient, and controlling the vehicle body stability control unit (ESP) to increase a rear drive slip rate threshold.
In the embodiment of the invention, when the locked-rotor state of the rear axle motor is detected, all subsystems of the vehicle are coordinated according to a preset processing mode, and the running state of the vehicle starting on the sandy ground is controlled.
For example, as shown in fig. 2, the entire vehicle control module sends the current vehicle state and the corresponding mode signal HCU _ drvmmodselect to each subsystem, the system comprises an engine Control unit EMS (Engine Management System), a transmission Control unit DCT (Dual Clutch Transmission), a vehicle body stability Control unit ESP (electronic stability program) and a motor Control unit MCU (Motor Control Unit), wherein each subsystem combines the available state of the system according to a mode signal and sends a state signal to an HCU, the HCU receives the state signal of each system and combines the current battery electric quantity SOC (State of Charge), a torque distribution controller controls a rear axle motor to output torque in a preset torque gradient increasing mode, and controlling an ESP (electronic stability program) to increase a rear-drive slip rate threshold, and coordinating input information of a driver to carry out final execution so as to assist the vehicle to be in a stable state when the vehicle starts to drive in a sandy place.
In the embodiment of the invention, when the sand driving function of the automobile is detected to be started, the current speed of the automobile is obtained; judging whether the automobile is in a starting state or not according to the current speed; if the automobile is in a starting state, judging whether the rear axle motor is in a locked-rotor state; if the rear axle motor is in a locked-rotor state, executing a preset control strategy corresponding to the sand starting function; the preset control strategy corresponding to the sand starting function comprises the following steps: and controlling the rear axle motor to output torque in a mode of increasing a preset torque gradient, and controlling the vehicle body stability control unit (ESP) to increase a rear drive slip rate threshold. The aim of more accurately assisting the driver to control the vehicle to start stably in the sand through the preset control strategy for starting in the sand is achieved.
Example two
Referring to fig. 3, which is a flowchart of a vehicle starting method according to an embodiment of the present invention, the method is applied to a hybrid electric vehicle, where the vehicle includes a rear axle motor, and the method may specifically include the following steps:
step 201, when the sand driving function of the automobile is detected to be started, the current speed of the automobile is obtained.
This step is the same as step 101 and will not be described in detail here.
And step 202, if the current vehicle speed is 0, acquiring the current execution gear of the automobile.
In the embodiment of the invention, when the obtained current vehicle speed is 0, the driving intention of the current driver is further obtained through the gear control module, and the driving gears can be divided into a reverse gear, a driving gear and a parking gear.
And step 203, if the current execution gear of the automobile is a driving gear, the automobile is in a starting state.
And 204, if the automobile is in a starting state, judging whether an accelerator pedal of the automobile is stepped on.
Step 205, if the accelerator pedal of the automobile is stepped on, determining whether the product of the torque of the rear axle motor and the motor speed is 0.
In the embodiment of the invention, when the vehicle speed VehSpd is 0, the current gear is judged, if the vehicle is not in the driving gear, namely Neutral or park, the vehicle is kept in the Parking mode, namely P-gear Parking or EPB Parking, if the gear is in the driving gear at the moment, the judgment on the accelerator pedal is continued, if the accelerator pedal is not pressed (namely AccelPedalPosn is 0), the driver is considered to request the crawling mode, namely the crawling speed is judged by DCT and the engine torque is calculated, and if the pressing of the accelerator pedal is detected (namely AccelPedalPosn is greater than 0), the vehicle is judged to be in Sand drive off. At the moment, the torque and the rotating speed of the rear axle motor are judged, and if the product of the rotating speed and the torque of the motor is 0.
And step 206, if the product of the torque of the rear axle motor and the motor speed is 0, the rear axle motor is in a locked-rotor state.
In the embodiment of the invention, when the product of the rotating speed and the torque of the motor is 0, the motor has a locked-rotor tendency, and if the product of the rotating speed and the torque of the motor is not 0, the motor is considered to work normally, and a sand ground mode is requested.
Specifically, due to the relationship of energy recovery, the state of the motor cannot be judged according to the positive and negative of the motor torque signal, so that the states of the motor speed and the torque are judged simultaneously, and the motor is determined to have a stalling tendency when the product of the motor speed and the torque is 0.
Step 207, if the rear axle motor is in a locked-rotor state, executing a preset control strategy corresponding to the sand starting function; the preset control strategy corresponding to the sand starting function comprises the following steps: and controlling the rear axle motor to output torque in a mode of increasing a preset torque gradient, and controlling the vehicle body stability control unit (ESP) to increase a rear drive slip rate threshold.
In the embodiment of the invention, if the rear axle motor is in a locked-rotor trend state, a preset control strategy corresponding to a sand starting function is executed, wherein the sand starting preset strategy is shown as a table I:
Figure BDA0001527948510000081
watch 1
Among them, the control signal is transmitted to each subsystem, for example, a control signal is transmitted to an ECM (Engine control module) to control a torque response speed, a signal is transmitted to a TCU (Transmission control unit Transmission control system) to control a Transmission torque, a signal is transmitted to an E-motor, a torque is output at a certain rising gradient based on a target torque output, and a signal is transmitted to an ESP (Electronic Stability Program) to increase a rear axle slip rate threshold.
Specifically, as shown in fig. 4, the target torque Ttgt is calculated in such a manner that, when the vehicle is running on a sand road with a slope of α,
∑F＝Ffa+Fra-Fi-Fj-Ff(1)
Fi＝Gsinα (2)
Fj＝μGcosα (3)
Fttraction, sum of vehicle front axle traction and rear axle traction, Ffa+Fra
FiThe slope resistance is represented by the component force of the gravity of the automobile along the slope, G is the gravity acting on the automobile, G is mg, m is the mass of the automobile, G is the gravity acceleration, and α is the slope.
FjThe rolling resistance is that the gravity component of the automobile vertical to the road surface of the ramp is Gcos α, and the friction coefficient of the road surface is mu.
FfOther resistance, the resultant of other forces that the automobile needs to overcome when running with acceleration, including air resistance, acceleration resistance, and the like.
When the vehicle runs on a slope, ∑ F is required to be larger than or equal to 0 to ensure that the vehicle can start, namely:
Ffa+Fra-Fi-Fj-Ff≥0 (4)
considering the critical situation, ∑ F is 0
Fra＝Fi+Fj+Ff-Ffa(5)
Figure BDA0001527948510000091
Thus, the target torque T can be obtainedtgt
Figure BDA0001527948510000092
And 208, if the rear axle motor is not in a locked-rotor state, executing a preset control strategy corresponding to the sand driving function, and controlling the driving state of the automobile.
In the embodiment of the invention, if the rear axle motor of the vehicle does not have the locked rotor and locked rotor trend, the vehicle is continuously controlled according to the sand driving mode, as shown in the table II:
Figure BDA0001527948510000101
watch two
Preferably, step 208 includes sub-steps A11-A13;
in sub-step a11, the hybrid control unit HCU sends control signals of a preset control strategy corresponding to the sand driving function to the engine control unit EMS, the transmission control unit DCT, the vehicle body stability control unit ESP, and the motor control unit MCU, respectively.
In the embodiment of the invention, for a PHEV (hybrid electric vehicle), two power sources are generally provided, wherein the first power source is responsible for controlling front axle driving, the torque value is the sum of engine torque and motor torque multiplied by speed ratio, the second power source is responsible for rear axle driving, and the rear axle torque is derived from a 350V high-voltage battery and a rear axle motor. The torque distribution strategy and the torque framework of the front and rear axles are arranged in the HCU, and the HCU respectively controls the torque of the front and rear axles according to the vehicle speed, the gradient, the steering wheel rotation angle, the static axle load, the SOC (battery state of charge) of the high-voltage battery and other variables. Meanwhile, when the vehicle is unstable (wheel slip, deceleration is too large, steering is insufficient or excessive), the ESP system performs control to perform torque interference or brake force distribution on the front and rear axles. When a vehicle runs on a road surface, the tire is subjected to frictional resistance of the ground, and the force can be decomposed into longitudinal force and lateral force, which cancel each other. Longitudinal forces affect the steering ability of the vehicle and lateral forces affect the stability ability of the vehicle. Under the influence of the characteristics of the tire, the lateral force and the slip ratio of the tire are in a linear relationship in a certain range, and when the slip ratio exceeds a certain range (about 20%), the lateral force and the slip ratio are in a nonlinear relationship, and the stability control capability is reduced, so that the ESP generally controls the slip ratio of the driving wheel to be between 15% and 20%, so that the ESP has a certain steering capability and ensures the stability of the automobile.
Therefore, when the hybrid control unit HCU transmits a control signal corresponding to a preset control strategy corresponding to the sand driving function, such as a torque output signal, to the engine control unit EMS and the transmission control unit DCT, a slip rate control signal is transmitted to the vehicle body stability control unit ESP and the motor control unit MCU.
And a substep a12, in which the hybrid control unit HCU acquires status signals returned by the engine control unit EMS, the transmission control unit DCT, the vehicle body stability control unit ESP, and the motor control unit MCU.
In the embodiment of the invention, after the hybrid control unit HCU sends the control signal, the hybrid control unit HCU further receives the status signals returned by the sub-units, for example, receives the torque output signals of the engine control unit EMS and the transmission control unit DCT, and receives the slip ratio control signals returned by the vehicle body stability control unit ESP and the motor control unit MCU.
Sub-step A13, the hybrid control unit HCU combines the returned state signal and the electric quantity of the rear axle motor to execute a preset control strategy corresponding to the sand driving function; the preset control strategy corresponding to the sand driving function comprises controlling the output of the starting torque and the high-speed torque of the automobile and providing the maximum torque transmission; and calculating and outputting the output torque of the front and rear shafts according to the opening degree of an accelerator pedal.
In the embodiment of the invention, after the hybrid control unit HCU receives the status signals returned by the subsystems, the HCU respectively controls the torques of the front axle and the rear axle according to the returned status signals and the variables of the current vehicle, such as the vehicle speed, the gradient, the steering wheel angle, the static axle load, the high-voltage battery SOC (battery state of charge), and the like, and controls the torque and the slip ratio required to be output by the front axle and the rear axle, thereby realizing the sand start auxiliary control function of the vehicle.
In summary, as shown in fig. 5, the invention provides a sand start system, which first determines a vehicle speed in a sand driving mode, determines a start state of a vehicle according to the vehicle speed and a gear, determines whether a stall exists in a rear axle motor according to a value of a product of a rotation speed and a torque of the rear axle motor in the start state, and if so, coordinates and controls a smooth start and a form state of the vehicle by controlling an engine module, a transmission module, a motor and an electronic stability control system in the vehicle, and displays parameters on an electronic instrument panel.
In the embodiment of the invention, the hybrid electric four-wheel drive system configuration based on the power configuration of P0+ P4 is used for judging whether a vehicle is in a starting state or not by detecting the running speed of the vehicle in a sand driving mode, further judging the stalling trend of a rear axle motor according to the motor state and the motor torque together in the sand driving mode, and realizing the control mode of the sand starting mode to ensure the smooth starting of the vehicle based on the calculation method of the target torque of the rear axle when the stalling trend exists.
EXAMPLE III
Referring to fig. 6, a block diagram of a vehicle starting device according to an embodiment of the present invention is a structural diagram of a vehicle starting device, where the vehicle starting device is applied to a hybrid vehicle, where the vehicle includes a rear axle motor, and the vehicle starting device includes:
the device comprises a vehicle speed acquisition module 301, a starting state judgment module 302, a motor state judgment module 303 and a sand starting module 304.
The functions of the modules and the interaction relationship between the modules are described in detail below with reference to fig. 7.
The vehicle speed obtaining module 301 is configured to obtain a current vehicle speed of the vehicle when it is detected that the vehicle starts a sand driving function;
a starting state judging module 302, configured to judge whether the vehicle is in a starting state according to the current vehicle speed;
preferably, the starting state determining module 302 includes:
the gear state obtaining submodule 3021 is configured to obtain a current execution gear of the automobile if the current vehicle speed is 0;
the starting state obtaining submodule 3022 is configured to, if the current execution gear of the vehicle is a driving gear, enable the vehicle to be in a starting state.
A motor state judgment module 303, configured to judge whether the rear axle motor is in a locked-rotor state if the automobile is in a starting state;
the sand starting module 304 is configured to execute a preset control strategy corresponding to a sand starting function if the rear axle motor is in a locked-rotor state; the preset control strategy corresponding to the sand starting function comprises the following steps: and controlling the rear axle motor to output torque in a mode of increasing a preset torque gradient, and controlling the vehicle body stability control unit (ESP) to increase a rear drive slip rate threshold.
Preferably, the sand launch module 304 includes:
an accelerator pedal state obtaining submodule 3041 for, if the vehicle is in a starting state, determining whether an accelerator pedal of the vehicle is stepped on;
a judgment submodule 3042, configured to judge whether a product of a torque of the rear axle motor and a motor speed is 0 if the accelerator pedal of the vehicle is stepped on in the motor state;
a determination submodule 3043 configured to, if a product of the torque of the rear axle motor and the motor speed is 0, determine that the rear axle motor is in a locked-rotor state.
Preferably, the method further comprises the following steps:
and a sand driving module 305, configured to execute a preset control strategy corresponding to the sand driving function if the rear axle motor is not in a locked-rotor state, so as to control a driving state of the vehicle.
Preferably, the sand driving module 305 includes:
the control signal sending submodule is used for the hybrid control unit HCU to respectively send control signals of a preset control strategy corresponding to the sand driving function to the engine control unit EMS, the transmission control unit DCT, the vehicle body stability control unit ESP and the motor control unit MCU;
the state signal acquisition submodule is used for acquiring state signals returned by the engine control unit EMS, the transmission control unit DCT, the vehicle body stability control unit ESP and the motor control unit MCU by the hybrid control unit HCU;
the control strategy execution submodule is used for the hybrid control unit HCU to execute a preset control strategy corresponding to the sand driving function by combining the returned state signal and the electric quantity of the rear axle motor; the preset control strategy corresponding to the sand driving function comprises controlling the output of the starting torque and the high-speed torque of the automobile and providing the maximum torque transmission; and calculating and outputting the output torque of the front and rear shafts according to the opening degree of an accelerator pedal.
In the embodiment of the invention, the hybrid electric four-wheel drive system configuration based on the power configuration of P0+ P4 is used for judging whether a vehicle is in a starting state or not by detecting the running speed of the vehicle in a sand driving mode, further judging the stalling trend of a rear axle motor according to the motor state and the motor torque together in the sand driving mode, and realizing the control mode of the sand starting mode to ensure the smooth starting of the vehicle based on the calculation method of the target torque of the rear axle when the stalling trend exists.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (10)

1. A vehicle take-off method, applied to a hybrid vehicle, the vehicle including a rear axle motor, the method comprising:
when the sand driving function of the automobile is detected to be started, the current speed of the automobile is obtained;
judging whether the automobile is in a starting state or not according to the current speed;
if the automobile is in a starting state, judging whether the rear axle motor is in a locked-rotor state;
if the rear axle motor is in a locked-rotor state, executing a preset control strategy corresponding to the sand starting function; the preset control strategy corresponding to the sand starting function comprises the following steps: and controlling the rear axle motor to output torque in a mode of increasing a preset torque gradient, and controlling a vehicle body stability control unit (ESP) to increase a rear drive slip rate threshold.
2. The vehicle startup method according to claim 1, wherein the step of determining whether the vehicle is in a startup state according to the current vehicle speed comprises:
if the current speed is 0, acquiring the current execution gear of the automobile;
and if the current execution gear of the automobile is a driving gear, the automobile is in a starting state.
3. The vehicle starting method according to claim 1, wherein the step of determining whether the rear axle motor is in a locked-rotor state if the vehicle is in a starting state comprises:
if the automobile is in a starting state, judging whether an accelerator pedal of the automobile is stepped on;
if the accelerator pedal of the automobile is stepped on, judging whether the product of the torque of the rear axle motor and the motor rotating speed is 0;
and if the product of the torque of the rear axle motor and the rotating speed of the motor is 0, the rear axle motor is in a locked-rotor state.
4. The vehicle take-off method as claimed in claim 1, further comprising:
and if the rear axle motor is not in a locked-rotor state, executing a preset control strategy corresponding to the sand driving function, and controlling the driving state of the automobile.
5. The vehicle startup method according to claim 1 or 4, wherein the step of executing the preset control strategy corresponding to the sand driving function to control the driving state of the automobile comprises:
the hybrid power control unit HCU sends control signals of a preset control strategy corresponding to the sand driving function to an engine control unit EMS, a transmission control unit DCT, a vehicle body stability control unit ESP and a motor control unit MCU respectively;
the hybrid power control unit HCU acquires state signals returned by the engine control unit EMS, the transmission control unit DCT, the vehicle body stability control unit ESP and the motor control unit MCU;
the hybrid power control unit HCU is combined with the returned state signal and the electric quantity of the rear axle motor to execute a preset control strategy corresponding to the sand driving function; the preset control strategy corresponding to the sand driving function comprises controlling the output of the starting torque and the high-speed torque of the automobile and providing the maximum torque transmission; and calculating and outputting the output torque of the front and rear shafts according to the opening degree of an accelerator pedal.
6. A vehicle starting device, characterized in that the device is applied to a hybrid vehicle, the vehicle including a rear axle motor, the device comprising:
the vehicle speed acquisition module is used for acquiring the current vehicle speed of the vehicle when the vehicle is detected to start a sand driving function;
the starting state judging module is used for judging whether the automobile is in a starting state or not according to the current speed;
the motor state judging module is used for judging whether the rear axle motor is in a locked-rotor state or not if the automobile is in a starting state;
the sand starting module is used for executing a preset control strategy corresponding to a sand starting function if the rear axle motor is in a locked-rotor state; the preset control strategy corresponding to the sand starting function comprises the following steps: and controlling the rear axle motor to output torque in a mode of increasing a preset torque gradient, and controlling a vehicle body stability control unit (ESP) to increase a rear drive slip rate threshold.
7. The vehicle starting device according to claim 6, wherein the starting state determining means includes:
the gear state acquisition submodule is used for acquiring the current execution gear of the automobile if the current speed is 0;
and the starting state acquisition submodule is used for enabling the automobile to be in a starting state if the current execution gear of the automobile is a driving gear.
8. The vehicle launch device of claim 6, wherein the sand launch module comprises:
the accelerator pedal state acquisition submodule is used for judging whether an accelerator pedal of the automobile is stepped on or not if the automobile is in a starting state;
the judgment submodule is used for judging whether the product of the torque of the rear axle motor and the motor speed is 0 or not if the accelerator pedal of the automobile is stepped on in the motor state;
and the determining submodule is used for determining that the rear axle motor is in a locked-rotor state if the product of the torque of the rear axle motor and the rotating speed of the motor is 0.
9. The vehicle starting device according to claim 6, characterized by further comprising:
and the sand driving module is used for executing a preset control strategy corresponding to the sand driving function and controlling the running state of the automobile if the rear axle motor is not in a locked-rotor state.
10. Vehicle launch device according to claim 6 or 9, characterised in that said sand driving module comprises:
the control signal sending submodule is used for the hybrid control unit HCU to respectively send control signals of a preset control strategy corresponding to the sand driving function to the engine control unit EMS, the transmission control unit DCT, the vehicle body stability control unit ESP and the motor control unit MCU;
the state signal acquisition submodule is used for acquiring state signals returned by the engine control unit EMS, the transmission control unit DCT, the vehicle body stability control unit ESP and the motor control unit MCU by the hybrid control unit HCU;
the control strategy execution submodule is used for the hybrid control unit HCU to execute a preset control strategy corresponding to the sand driving function by combining the returned state signal and the electric quantity of the rear axle motor; the preset control strategy corresponding to the sand driving function comprises controlling the output of the starting torque and the high-speed torque of the automobile and providing the maximum torque transmission; and calculating and outputting the output torque of the front and rear shafts according to the opening degree of an accelerator pedal.
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CN112896142A (en) * 2020-12-30 2021-06-04 东风小康汽车有限公司重庆分公司 Vehicle control method and device, storage medium and vehicle control unit
CN112590564B (en) * 2021-01-04 2022-08-05 潍柴动力股份有限公司 Motor torque control method and device, electronic equipment and storage medium
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