CN114347974B - Method for controlling braking torque of hybrid electric vehicle and storage medium - Google Patents
Method for controlling braking torque of hybrid electric vehicle and storage medium Download PDFInfo
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- CN114347974B CN114347974B CN202210078469.1A CN202210078469A CN114347974B CN 114347974 B CN114347974 B CN 114347974B CN 202210078469 A CN202210078469 A CN 202210078469A CN 114347974 B CN114347974 B CN 114347974B
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- 238000000034 method Methods 0.000 title claims abstract description 24
- 230000008878 coupling Effects 0.000 claims abstract description 6
- 238000010168 coupling process Methods 0.000 claims abstract description 6
- 238000005859 coupling reaction Methods 0.000 claims abstract description 6
- 238000011084 recovery Methods 0.000 claims description 6
- 238000002347 injection Methods 0.000 claims description 4
- 239000007924 injection Substances 0.000 claims description 4
- 239000000446 fuel Substances 0.000 abstract description 10
- 239000003921 oil Substances 0.000 description 12
- 230000005540 biological transmission Effects 0.000 description 7
- 230000002035 prolonged effect Effects 0.000 description 6
- 239000003638 chemical reducing agent Substances 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000010705 motor oil Substances 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/62—Hybrid vehicles
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Abstract
The invention discloses a method for controlling braking torque of a hybrid electric vehicle, which comprises the following steps: acquiring a requested braking torque and an actual gear, and when the actual gear is smaller than or equal to a set critical gear, disconnecting the clutch, and controlling the rear axle motor and/or the front axle motor to output the braking torque according to the magnitude of the requested braking torque; when the actual gear is larger than the set critical gear, the coupling clutch firstly controls the engine to output the braking torque according to the magnitude of the requested braking torque, and then controls the rear axle motor and/or the front axle motor to output the braking torque if the requested braking torque cannot be met. According to the invention, under the condition of ensuring NVH performance, the engine is braked by fuel cut-off preferentially, then the front and rear axle motors are braked, and the fuel consumption is reduced by prolonging the fuel cut-off time of the engine.
Description
Technical Field
The invention relates to the technical field of automobile brake control, in particular to a method for controlling brake torque of a hybrid electric vehicle and a storage medium.
Background
Braking is a common working condition of hybrid electric vehicles, and more literature describes related techniques for recovering braking energy by using a motor. For electric vehicles with motors on front and rear axles, the braking torque of the front and rear motors is mostly distributed based on the principles of maximizing the adhesive force of the front and rear wheels and optimizing the motor efficiency.
Hybrid vehicles are configured with an engine, unlike electric vehicles. There are many hybrid drive operating conditions based on the operating principle of such vehicles. The engine may be in an operating state or may be in a stopped state during braking. When the electric quantity is sufficient, the motor can be used for driving, and the engine is more in a stop state. When the electric quantity is insufficient, the engine is used for providing driving moment, and even if the electric quantity is insufficient, the engine is not stopped during braking. The driver is considered to finish braking at any time to accelerate, and the motor does not have enough energy source to drive, so that the vehicle can normally control and accelerate, and the hybrid electric vehicle has common working conditions that the engine can not stop running even in braking, so that the fuel consumption can be increased.
Related technical methods for controlling fuel cut of an engine are applied to traditional gasoline engine vehicles, for example, chinese patent CN113250833A discloses a method for controlling fuel cut of an engine in a vehicle sliding stage. The purpose is to achieve the purpose of saving fuel by injecting fuel as little as possible when the torque output by the engine is not needed.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a method for controlling braking torque of a hybrid electric vehicle and a storage medium.
In order to achieve the above object, the present invention provides a method for controlling braking torque of a hybrid electric vehicle, comprising: acquiring a requested braking torque and an actual gear, and when the actual gear is smaller than or equal to a set critical gear, disconnecting the clutch, and controlling the rear axle motor and/or the front axle motor to output the braking torque according to the magnitude of the requested braking torque; when the actual gear is larger than the set critical gear, the coupling clutch firstly controls the engine to output the braking torque according to the magnitude of the requested braking torque, and then controls the rear axle motor and/or the front axle motor to output the braking torque if the requested braking torque cannot be met.
Further, the method for determining the set critical gear includes controlling only the engine to output braking torque, obtaining NVH performance indexes of the engine under each gear by adjusting the vehicle speed, and taking the first gear as the set critical gear when the NVH performance indexes of the first gear do not meet the NVH performance target and the NVH performance indexes of the higher-order gears of the first gear meet the NVH performance target.
The NVH performance index comprises engine vibration frequency, engine noise and a tester score, and the NVH performance target is met when the engine vibration frequency is in a set frequency interval, the engine noise is smaller than a noise set value, and the tester score is larger than the set score.
Further, the method for determining the requested braking torque comprises the step of calibrating the opening degree of a brake pedal.
Further, the real-time vehicle speed is also obtained, when the real-time gear is the highest gear and the real-time vehicle speed is in the highest gear and the vehicle speed is in the advanced gear-shifting speed interval, if the requested braking torque is larger than the engine braking torque in the highest gear and smaller than the engine braking torque in the second high gear, the gearbox is controlled to actively shift down to the second high gear, and the engine is controlled to output the engine braking torque in the second high gear. Therefore, the engine speed is kept at a higher level by reducing the gear in advance and increasing the speed reduction ratio, the time period from the higher speed to the recovery of the oil injection speed of the engine can be prolonged, the oil-break time of the engine is prolonged as much as possible, and the oil consumption is further reduced.
Further, when the real-time gear is the highest gear and the real-time vehicle speed is in the highest gear in advance gear-shifting speed interval, if the requested braking torque is smaller than or equal to the engine braking torque in the highest gear, the gear of the gearbox is controlled to be unchanged, and the engine outputs the engine braking torque in the highest gear.
Further, when the real-time gear is larger than the set critical gear and the real-time vehicle speed is not in the highest gear advanced gear-down speed interval, the engine is controlled to output the engine braking torque under the real-time gear.
Further, the lower limit value of the highest gear advanced downshift vehicle speed section is the highest gear downshift critical vehicle speed.
Further, when the requested braking torque is larger than the engine braking torque, the rear axle motor is controlled to output the braking torque, and when the rear axle motor still cannot meet the rest requested braking torque, the front axle motor is controlled to output the braking torque.
Further, when the front axle motor still cannot meet the residual required braking torque, the brake caliper is controlled to output the braking torque.
Further, when the engine outputs braking torque and the engine speed is greater than the recovered oil injection speed, the engine oil cut-off is controlled.
Further, when the real-time vehicle speed is smaller than the creep critical vehicle speed, the engine, the front shaft motor and the rear shaft motor are controlled to not output braking torque.
The invention also provides a storage medium containing an execution instruction, wherein the execution instruction is processed by a data processing device, and the data processing device executes the method for controlling the braking torque of the hybrid electric vehicle.
The invention has the beneficial effects that: and the oil consumption during engine braking is reduced under the condition of ensuring NVH performance. When the actual gear is smaller than or equal to the set critical gear, the vibration sense is aggravated because the transmission ratio is larger, at the moment, the idle speed idle rotation of the engine is controlled without braking, and the braking energy is recovered only through the front and rear shaft motors, so that the vibration and noise of the engine can be reduced and transmitted to the vehicle body through the transmission system, and the NVH performance is improved; when the actual gear is larger than the set critical gear, the coupling clutch cannot cause insufficient NVH performance, the engine is controlled to break oil and output braking torque firstly according to the magnitude of the requested braking torque, and if the requested braking torque cannot be met, the rear axle motor and/or the front axle motor is controlled to output braking torque, so that the oil breaking time of the engine is prolonged, and braking energy recovery is carried out while the oil consumption is reduced preferentially.
Drawings
Fig. 1 is a schematic diagram of a power configuration structure of a hybrid electric vehicle according to the present invention.
FIG. 2 is a flow chart of a control method of the present invention.
The reference numerals of the components in the drawings are as follows: the engine 1, the clutch 2, the front axle motor 3, the gearbox 4, the front axle differential 5, the front axle 6, the front wheels 7, the power battery 8, the high-voltage distribution box 9, the rear axle motor 10, the speed reducer 11, the rear axle differential 12, the rear axle 13 and the rear wheels 14.
Detailed Description
The following detailed description is presented to provide further details in the context of the claimed subject matter, as will be apparent to those skilled in the art. The scope of the invention is not limited to the specific examples below. It is also within the scope of the invention to include the claims of the present invention as made by those skilled in the art, rather than the following detailed description.
As shown in fig. 1, a hybrid electric vehicle power configuration structure comprises a front axle power system and a rear axle power system, wherein the front axle power system comprises an engine 1, a clutch 2, a front axle motor 3, a gearbox 4 and a front axle differential 5 which are sequentially connected; the rear axle power system comprises a rear axle motor 10, a speed reducer 11 and a rear axle differential 12 which are sequentially connected, wherein the front axle motor 3 and the rear axle motor 10 are both connected to a power battery 8 through a high-voltage distribution box 9, and when a clutch is coupled, an engine runs and drives the front axle motor 3 to generate power, and torque can be output together with the front axle motor to drive front wheels to rotate; when the clutch is separated, the engine can only idle, the front axle motor can not generate electricity, and only torque can be output to drive the front wheels to rotate; the rear axle motor cannot generate electricity, either does not output torque or outputs torque to drive the rear wheels to rotate.
When the driver presses the brake pedal, that is, the requested brake torque exists, if the clutch is released, the engine cannot output the brake torque, braking energy recovery can only be performed through the front shaft motor and/or the rear shaft motor, and if the clutch is coupled, the engine can output the brake torque.
When the engine outputs the engine braking torque in the current gear, the front axle motor and the rear axle motor each output the respective maximum allowable braking torque, the total braking torque at this time is referred to as the powertrain maximum braking torque.
As shown in fig. 2, taking an example of an 8-gear automatic gearbox vehicle type, wherein the critical gear is 6 gears, under normal working conditions, the critical gear shifting speed of 6 gears and 7 gears is 60km/h, the critical gear shifting speed of 7 gears and 8 gears is 80km/h, more than 80km/h is up to 210km/h and is 8 gears, under certain special working conditions, 8 gears are allowed to be reduced to 7 gears in advance, the advanced gear-down interval of 8 gears is set to 80 km/h-96 km/h, and the control method of the braking torque of the hybrid electric vehicle is as follows.
1. When the real-time speed is smaller than the creep critical speed, the engine, the front shaft motor and the rear shaft motor are controlled to not output braking torque. Because the output of the brake torque by the powertrain at this time does not further reduce the vehicle speed, the brake torque can only be provided by driving the brake caliper to clamp the brake chuck.
2. And when the speed is greater than or equal to the creep critical speed and less than 60km/h, the gear of the gearbox is 1-6 gears, and the first torque distribution mode is entered. Since the coupling clutch in this case transmits the vibrations of the engine to the vehicle body via the transmission system, the clutch is disconnected in this case in order to increase the comfort of the driver, so that the engine speed is gradually reduced to idle operation. When the requested braking torque is smaller than or equal to the maximum allowable braking torque of the rear axle motor, the requested braking torque is met only through the rear axle motor, and when the requested braking torque is larger than the maximum allowable braking torque of the rear axle motor and smaller than or equal to the sum of the maximum allowable braking torques of the front axle motor and the rear axle motor, the rear axle motor outputs the maximum allowable braking torque, and the front axle motor outputs the rest requested braking torque; when the requested braking torque is greater than the sum of the maximum allowable braking torques of the front and rear axle motors, the remaining requested braking torque is output through the brake calipers. The reason why the rear axle motor provides braking torque preferentially over the front axle motor is that: the rear axle motor transmits braking torque to the wheel rim only through one reduction gearbox and a differential mechanism, and the front motor braking force transmits braking torque to the wheel rim through the 8-speed gearbox and the differential mechanism, because the gearbox is complex in shaft system and higher in transmission loss than the rear axle motor, the rear axle motor is good in transmission efficiency compared with the front axle motor.
3. When the vehicle speed is greater than or equal to 60km/h and less than 80km/h, the gearbox is positioned at 7 th gear, and the second torque distribution mode is entered. The clutch is coupled, the engine is controlled to cut off oil, the engine outputs engine braking torque under 7 gears, when the requested braking torque is larger than the engine braking torque under 7 gears, the rear axle motor and the front axle motor are sequentially controlled to output braking torque, and when the requested braking torque is larger than the maximum braking torque of the power system, the rest requested braking torque is output through the brake calipers.
4. When the vehicle speed is greater than or equal to 80km/h and less than 96km/h, the transmission is first in 8 th gear and enters a third torque distribution mode. If the requested braking torque is smaller than or equal to the engine braking torque under 8 gears, the gear of the gearbox is controlled to be unchanged, and the engine outputs the engine braking torque under 8 gears; and if the requested braking torque is greater than the engine braking torque in 8 gears and less than the engine braking torque in 7 gears, controlling the gearbox to actively downshift to 7 gears, and controlling the engine to output the engine braking torque in 7 gears. Therefore, the engine speed is kept at a higher level by reducing the gear in advance and increasing the speed reduction ratio, the time period from the higher speed to the recovery of the oil injection speed of the engine can be prolonged, the oil-break time of the engine is prolonged as much as possible, and the oil consumption is further reduced.
When the transmission is lowered to 7 gears, the requested braking torque is larger than the engine braking torque in 7 gears and smaller than the maximum braking torque of the power system, the rear axle motor and the front axle motor are sequentially controlled to output the braking torque, and when the requested braking torque is larger than the maximum braking torque of the power system, the rest requested braking torque is output through the brake calipers.
5. When the vehicle speed is greater than or equal to 96km/h and less than 210km/h, the gearbox is always positioned at 8 gears, and a fourth torque distribution mode is entered. The clutch is coupled, the engine is controlled to cut off oil, the engine outputs engine braking torque under 8 gears, when the requested braking torque is larger than the engine braking torque under 8 gears, the rear axle motor and the front axle motor are sequentially controlled to output braking torque, and when the requested braking torque is larger than the maximum braking torque of the power system, the rest requested braking torque is output through the brake calipers.
When the actual gear is greater than the critical gear 6, the coupling clutch cannot cause insufficient NVH performance, the engine is controlled to break oil and output braking torque preferentially according to the magnitude of the requested braking torque, and if the requested braking torque cannot be met, the rear axle motor and/or the front axle motor is controlled to output braking torque, so that the fuel breaking time of the engine is prolonged, and braking energy recovery is carried out while fuel consumption is reduced preferentially.
Claims (9)
1. A method for controlling braking torque of a hybrid vehicle, comprising: acquiring a requested braking torque and an actual gear, and when the actual gear is smaller than or equal to a set critical gear, disconnecting the clutch, and controlling the rear axle motor and/or the front axle motor to output the braking torque according to the magnitude of the requested braking torque; when the actual gear is larger than the set critical gear, the coupling clutch firstly controls the engine to output braking torque according to the magnitude of the requested braking torque, and then controls the rear axle motor and/or the front axle motor to output braking torque if the requested braking torque cannot be met;
the method for determining the set critical gear comprises the steps of controlling an engine to output braking torque only, obtaining NVH performance indexes of the engine under each gear by adjusting the speed of the vehicle, and taking the first gear as the set critical gear when the NVH performance indexes of the first gear do not meet the NVH performance target and the NVH performance indexes of the higher gear of the first gear meet the NVH performance target.
2. The hybrid vehicle brake torque control method according to claim 1, characterized in that: and acquiring a real-time vehicle speed, and controlling the gearbox to actively downshift to the second high gear and controlling the engine to output the engine braking torque in the second high gear if the requested braking torque is larger than the engine braking torque in the highest gear and smaller than the engine braking torque in the second high gear when the real-time gear is the highest gear and the real-time vehicle speed is in the highest gear in advance downshift speed interval.
3. The hybrid vehicle brake torque control method according to claim 2, characterized in that: when the real-time gear is larger than the set critical gear and the real-time vehicle speed is not in the highest gear forward gear-down speed interval, controlling the engine to output the engine braking torque under the real-time gear.
4. The hybrid vehicle brake torque control method according to claim 3, characterized in that: and the lower limit value of the highest gear forward downshift vehicle speed section is the highest gear downshift critical vehicle speed.
5. A hybrid vehicle brake torque control method according to claim 1 or 3, characterized in that: when the request braking torque is larger than the engine braking torque, the rear axle motor is controlled to output the braking torque, and when the rear axle motor still cannot meet the residual request braking torque, the front axle motor is controlled to output the braking torque.
6. The method for controlling braking torque of a hybrid vehicle according to claim 5, characterized in that: and controlling the brake caliper to output the braking torque when the front axle motor still cannot meet the residual requested braking torque.
7. The hybrid vehicle brake torque control method according to claim 1, characterized in that: and when the engine outputs braking torque and the engine rotating speed is higher than the recovery oil injection rotating speed, controlling the engine to cut off oil.
8. The hybrid vehicle brake torque control method according to claim 1, characterized in that: when the real-time speed is smaller than the creep critical speed, the engine, the front shaft motor and the rear shaft motor are controlled to not output braking torque.
9. A storage medium, characterized by: it contains an execution instruction which, when processed by a data processing device, executes the hybrid vehicle brake torque control method according to any one of claims 1 to 8.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210078469.1A CN114347974B (en) | 2022-01-24 | 2022-01-24 | Method for controlling braking torque of hybrid electric vehicle and storage medium |
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| CN202210078469.1A CN114347974B (en) | 2022-01-24 | 2022-01-24 | Method for controlling braking torque of hybrid electric vehicle and storage medium |
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| CN114347974B true CN114347974B (en) | 2023-12-19 |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101024397A (en) * | 2006-02-22 | 2007-08-29 | 三菱扶桑卡客车株式会社 | Control device for hybrid electric vehicle |
| CN106184194A (en) * | 2014-11-27 | 2016-12-07 | 现代自动车株式会社 | The regenerating brake control method of motor vehicle driven by mixed power |
| CN110239543A (en) * | 2018-03-07 | 2019-09-17 | 丰田自动车株式会社 | Braking force controller, device and method |
| CN111619359A (en) * | 2019-02-28 | 2020-09-04 | 北京新能源汽车股份有限公司 | Control method for recovering vehicle braking energy, vehicle control unit and vehicle |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109720331A (en) * | 2017-10-31 | 2019-05-07 | 长城汽车股份有限公司 | A kind of the torque adjusting method and device of hybrid vehicle |
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- 2022-01-24 CN CN202210078469.1A patent/CN114347974B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101024397A (en) * | 2006-02-22 | 2007-08-29 | 三菱扶桑卡客车株式会社 | Control device for hybrid electric vehicle |
| CN106184194A (en) * | 2014-11-27 | 2016-12-07 | 现代自动车株式会社 | The regenerating brake control method of motor vehicle driven by mixed power |
| CN110239543A (en) * | 2018-03-07 | 2019-09-17 | 丰田自动车株式会社 | Braking force controller, device and method |
| CN111619359A (en) * | 2019-02-28 | 2020-09-04 | 北京新能源汽车股份有限公司 | Control method for recovering vehicle braking energy, vehicle control unit and vehicle |
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| CN114347974A (en) | 2022-04-15 |
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