Anti-folding brake control method for new energy tractor and trailer

Abstract

The invention discloses an anti-folding brake control method for a new energy tractor and a trailer, and belongs to the technical field of new energy vehicle braking. The method specifically comprises the steps that when braking is light braking, a tractor only starts electric braking, and a trailer starts slight air braking; when the braking is heavier braking, except for starting electric braking, all pneumatic brakes of the tractor provide corresponding braking air pressure according to calibration parameters, and the trailer provides corresponding pneumatic braking air pressure according to loads; when the braking is emergency braking, different braking air pressures are provided for each pneumatic brake of the tractor and the trailer according to pre-calibrated parameters, and then automatic adjustment is carried out according to wheel speed signals of all vehicles and signals fed back by a vehicle body stabilizing system. The braking force redistribution method is simple and is not limited by whether the trailer is provided with a power battery or not, the braking stability of the vehicle can be guaranteed, the kinetic energy of the vehicle can be recycled to the maximum extent, and the economical efficiency of the vehicle is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicle braking, and more specifically to a braking control method for preventing folding of a new energy tractor and a trailer. Background Art

[0002] For traditional energy tractors-trailers, due to the lack of vehicle kinetic energy recovery function, the kinetic energy reduced by the vehicle during braking is all lost due to the friction heat generation of the brakes. During braking, the braking forces on all vehicle wheels including the tractor and the trailer are distributed in a fixed ratio, and the braking forces of the tractor and the trailer can only adjust the magnitude of the braking force under the extreme conditions when the ABS is activated. Since new energy vehicles have a braking energy recovery function, when lightly braking, the motor immediately switches to the generator mode, transfers the kinetic energy of the vehicle from the drive axle to the motor as the power for generating electricity, and stores the generated electric energy in the vehicle's power battery. At this time, the braking force of the vehicle is only provided by the drive axle. When the braking of the vehicle is only provided by the electric drive axle, during a turning condition of the vehicle, the trailer is likely to push the tractor, causing a folding accident of the tractor and the trailer.

[0003] To solve the above problems, Chinese Patent with application publication number CN 117227491A discloses a coordinated regenerative braking control method for an electric tractor and an electric trailer, including a vehicle running state detection unit, a vehicle regenerative braking state calculation unit, a vehicle regenerative braking state division unit, and a vehicle braking torque calculation and distribution unit; the coordinated control of the regenerative braking process of the electric tractor and the electric trailer is carried out through the vehicle running state detection unit, the vehicle regenerative braking state calculation unit, the vehicle regenerative braking state division unit, and the vehicle braking torque calculation and distribution unit.

[0004] However, the above patent involves numerous parameters and complex calculations, and based on "the electric tractor is a two-axle vehicle, the electric trailer has only one axle, and the electric drive axle of the electric trailer is installed at the electric trailer axle; the electric tractor is equipped with a power battery, and the electric trailer is equipped with a power battery", the calculation, division, and distribution of the vehicle regenerative braking state all involve parameters related to the electric drive axle of the electric trailer, such as: the load Fqh borne by the electric drive axle of the electric tractor, the load Fg borne by the electric drive axle of the electric trailer, the bridge braking force distribution factor ig of the electric trailer axle, etc. Therefore, this method is only applicable to the regenerative braking process of the electric tractor and the electric trailer, and it is difficult to be applicable to the coordinated control of the regenerative braking of a tractor and a trailer where the trailer is not powered. Summary of the Invention

[0005] The present invention provides a braking control method for preventing folding of a new energy tractor and a trailer to solve problems such as the existing methods for preventing folding of a tractor and a trailer, which involve many parameters, complex calculations, and are only applicable to trailers with power batteries.

[0006] The present invention adopts the following technical solution: A braking control method for preventing folding of a new energy tractor and a trailer, comprising the following steps: S1. Vehicle self-check, and enter the driving mode after passing. S2. The vehicle runs normally, and the system continuously estimates the load state of the vehicle according to the running parameters of the vehicle to provide braking data for system control. S3. Determine whether the driver steps on the brake pedal. If so, enter step S4; if not, maintain step S2. S4. Distribute braking in the following manner: When the braking is light braking, the tractor only activates the electric brake, and the trailer activates a slight air brake; when the braking is heavy braking, in addition to activating the electric brake, all air brakes of the tractor provide corresponding braking air pressure according to the calibrated parameters, and the trailer provides corresponding air braking air pressure according to the load; when the braking is emergency braking, first give different braking air pressures to each air brake of the tractor and the trailer with pre-calibrated parameters, and then automatically adjust according to the wheel speed signals of each vehicle and the signals fed back by the vehicle stability system.

[0007] In a preferred embodiment, the above light braking means that the pedal opening is below 20%; the heavy braking means that the pedal opening is between 20% and 70%; the emergency braking means that the pedal opening rapidly reaches above 70%.

[0008] In a preferred embodiment, during the light braking process of step S4 above, the driving state of the vehicle is continuously monitored. If the ESC, ABS or AEBS function is activated, the electric brake of the tractor is reduced.

[0009] In a preferred embodiment, during the heavy braking process of step S4 above, the driving state of the vehicle is continuously monitored. If the ESC, ABS or AEBS function is activated, the ESC, ABS or AEBS function is preferentially responded to.

[0010] In a preferred embodiment, when the braking in step S4 is heavy braking, a safety mode and an economic mode are introduced. In the safety mode, the braking force is distributed safely according to the load ratio of each wheel. At this time, the vehicle can make full use of the road surface adhesion coefficient, so that the vehicle can brake in the most stable and safe manner; in the economic mode, the electric brake is preferentially activated to recover the vehicle kinetic energy into electric energy to the maximum extent, and a parameter is set to represent the weight of the safety mode and the economic mode. This parameter is related to the brake pedal opening and the speed of stepping on the brake pedal and is calibrated.

[0011] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following advantages: The braking control method of the present invention changes the braking system of pure pneumatic braking to a braking force distribution scheme combining electric braking and pneumatic braking. When braking gently, the tractor only has electric braking, and the trailer also has slight pneumatic braking. When braking more severely, in addition to starting electric braking, all pneumatic brakes of the tractor provide corresponding braking air pressure according to the calibrated parameters, while the trailer provides corresponding pneumatic braking air pressure according to the load. The vehicle can adapt to no-load and full-load working conditions, comprehensively considering the handling stability and economy of the whole vehicle, and can independently control the braking force of each wheel of the tractor and the trailer, which can not only ensure the braking stability of the vehicle, but also maximize the recovery of the vehicle's kinetic energy to improve the economy of the vehicle. The method for redistributing the braking force of the present invention is simple and not limited by whether the trailer is equipped with a power battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a flowchart of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0013] The following describes the specific embodiments of the present invention with reference to the drawings. In order to fully understand the present invention, many details are described below, but for those skilled in the art, the present invention can be implemented without these details. For well-known components, methods and processes, no further detailed description will be given below.

[0014] This embodiment provides a braking control method for preventing folding of a new energy tractor and a trailer. Among them, the tractor has an electric motor and a power battery, and the tractor has a plurality of pneumatic brakes; while the trailer does not have a power system, and the trailer also has a plurality of pneumatic brakes. The braking control method includes the following steps: S1. The vehicle performs self-check, and enters the driving mode after passing.

[0015] S2. The vehicle runs normally, and the system continuously estimates the load state of the vehicle according to the running parameters of the vehicle, and continuously corrects it during driving to provide braking data for system control.

[0016] Specifically, according to the structure of the vehicle and the axle load distribution of no-load and full-load, the wheel loads of each wheel are calculated by using the data model built by simulink, and then the wheel loads are corrected by the vehicle weight calculated and analyzed by the system running data during vehicle operation.

[0017] The running parameters of the vehicle include motor torque, tractor speed, wheel speed, etc. The vehicle load parameters obtained by estimating and correcting through these running parameters can provide an important calculation basis for the braking distribution of the system.

[0018] S3. Determine whether the driver steps on the brake pedal. If so, enter step S4; if not, maintain step S2.

[0019] When the driver steps on the brake pedal, the braking is distributed in the following manner: (1)When the braking is light braking (i.e., the pedal opening is below 20%), the tractor only activates the electric braking to recover energy to improve economy, while the trailer activates slight air braking to ensure vehicle safety.

[0020] During this process, the driving state of the vehicle is monitored all the time. If functions such as ESC, ABS, and AEBS are activated, the braking system will be adjusted based on the principle of putting safety first, and the value of the electric braking recovery torque will be correspondingly reduced to ensure safety, and the braking force of each air brake will be adjusted according to a specific logic.

[0021] (2)When the braking is medium-heavy braking (i.e., the pedal opening is between 20% and 70%), both economy and safety are taken into account at this time. In addition to activating the electric braking, all air brakes of the tractor provide corresponding braking air pressure according to the calibrated parameters, and the trailer provides corresponding air braking air pressure according to the load. If the deceleration expected by the driver is not reached, the braking force of each air brake will be increased in a certain proportion.

[0022] In this medium-heavy braking, a safety mode and an economic mode are also introduced. In the safety mode, the braking force is distributed safely according to the load ratio of each wheel. At this time, the vehicle can make full use of the road adhesion coefficient, so that the vehicle can brake in the most stable and safe way; in the economic mode, the electric braking is preferentially activated to maximize the recovery of the vehicle's kinetic energy into electric energy, but there may be a risk that the vehicle is not very stable during braking at this time. Therefore, a parameter is set to represent the weight of the safety mode and the economic mode, and this parameter participates in the calculation of the braking force distribution as an important factor. This parameter is related to the braking pedal opening and the speed of stepping on the braking pedal and is calibrated. Therefore, the actual vehicle braking force distribution scheme is between the safety mode and the economic mode.

[0023] During this process, the driving state of the vehicle is monitored all the time. If functions such as ESC, ABS, and AEBS are activated, the ESC, ABS, or AEBS function will be preferentially responded to, and the braking force of each air brake will be adjusted according to a specific logic.

[0024] (3)When the braking is emergency braking (i.e., the pedal opening rapidly reaches more than 70%), at this time, the braking system focuses on safety. Different braking air pressures are first given to each air brake of the tractor and the trailer with pre-calibrated parameters, and then automatic adjustment is performed according to the wheel speed signals of each vehicle and the signals fed back by the vehicle stability system to ensure that the vehicle stops stably with the maximum deceleration safely.

[0025] The braking control method of the present invention is applicable to the mainstream configuration where there is no CAN communication between the current tractor and the trailer.

[0026] The above are only the specific embodiments of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantive modification of the present invention using this concept shall fall within the scope of infringement of the protection scope of the present invention.

Claims

1. A braking control method for preventing folding of a new energy tractor and trailer, characterized in that It includes the following steps: S1. The vehicle conducts a self-check. After passing, it enters the driving mode; S2. The vehicle runs normally. The system continuously estimates the load state of the vehicle according to the running parameters of the vehicle to provide braking data for system control; S3. Determine whether the driver steps on the brake pedal. If so, enter step S4; if not, maintain step S2; S4. Distribute braking in the following manner: When the braking is light braking, the tractor only activates the electric brake, and the trailer activates a slight air brake; when the braking is heavier braking, in addition to activating the electric brake, all air brakes of the tractor provide corresponding braking air pressure according to the calibrated parameters, and the trailer provides corresponding air braking air pressure according to the load; when the braking is emergency braking, first give different braking air pressures to each air brake of the tractor and the trailer with pre-calibrated parameters, and then automatically adjust according to the wheel speed signals of each vehicle and the signals feedback by the vehicle stability system.

2. The braking control method for preventing folding of a new energy tractor and trailer according to claim 1, wherein: The light braking refers to a pedal opening of less than 20%.

3. A braking control method for preventing folding of a new energy tractor and trailer according to claim 1, characterized in that: The heavier braking refers to a pedal opening between 20% and 70%.

4. The braking control method for preventing folding of a new energy tractor and trailer according to claim 1, characterized in that: The emergency braking refers to a pedal opening that rapidly reaches more than 70%.

5. A braking control method for preventing folding of a new energy tractor and trailer according to claim 1, characterized in that: During the light braking process of step S4, continuously monitor the driving state of the vehicle. If the ESC, ABS or AEBS function is activated, reduce the electric brake of the tractor.

6. The braking control method for preventing folding of a new energy tractor and trailer according to claim 1, characterized in that: During the heavier braking process of step S4, continuously monitor the driving state of the vehicle. If the ESC, ABS or AEBS function is activated, give priority to the corresponding ESC, ABS or AEBS function.

7. A braking control method for preventing folding of a new energy tractor and trailer as claimed in claim 1, characterized in that: When the braking in step S4 is heavier braking, introduce a safety mode and an economic mode. In the safety mode, the braking force is distributed safely according to the load ratio of each wheel. At this time, the vehicle can make full use of the road adhesion coefficient to brake the vehicle in the most stable and safe manner; in the economic mode, give priority to activating the electric brake to maximize the recovery of the vehicle's kinetic energy into electrical energy, and set a parameter to represent the weight of the safety mode and the economic mode. This parameter is associated with the brake pedal opening and the speed of stepping on the brake pedal and is calibrated.

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