New energy commercial vehicle brake-by-wire system equivalent braking force control method

Abstract

The invention discloses a new energy commercial vehicle brake-by-wire system equivalent braking force control method, and relates to the technical field of new energy vehicle brake-by-wire. On the basis of an equivalent braking force method, under the same braking strength request of an intelligent driving system, the total braking force output by composite braking is consistent with that during pure mechanical braking, electric braking force is preferentially used during braking, the braking force of a front motor and the braking force of a rear motor are distributed according to a pre-distribution coefficient # imgabs0 #, if the electric braking force does not meet the braking requirement, hydraulic braking force makes up, and if the electric braking force does not meet the braking requirement, the hydraulic braking force makes up for the braking requirement. And the hydraulic braking system distributes the hydraulic braking force according to the distribution coefficient # imgabs 1 #. By the adoption of the method, a brake system does not need to be transformed, an intelligent driving system does not need to be matched again, only the vehicle brake-by-wire function needs to be flexibly and rapidly matched through the intelligent chassis, a large amount of calibration work of commercial vehicle composite braking is reduced, and the development period is shortened; meanwhile, the driving mileage can be effectively increased, the response speed of a braking system is increased, and the braking characteristic of an original vehicle and the driving habit and braking feeling of a driver are not changed.

Description

Technical Field

[0001] The present invention relates to the technical field of wire-controlled braking of new energy vehicles, and more specifically to an equivalent braking force control method of a wire-controlled braking system of a new energy commercial vehicle. Background Art

[0002] In recent years, intelligent chassis wire control technology has received great attention from domestic and foreign manufacturers, and related technologies have developed rapidly. It is a common practice for many manufacturers to upgrade the brake systems of existing models to wire control to support the wire control commands of the intelligent driving system. Due to the complex and changeable vehicle conditions, the development of wire control brake technology for new energy commercial vehicles is relatively slow. At present, most of them use pure mechanical wire control brakes, which results in generally high energy consumption and poor braking control accuracy. As the biggest highlight of new energy vehicles, motor braking can perfectly make up for the defects of existing wire control brakes and solve the above problems by integrating with mechanical brakes.

[0003] A Chinese patent with publication number CN 116533954A discloses a braking force control method, system and vehicle based on a wire-controlled chassis. The method steps include: obtaining a data signal of a piezoelectric pressure sensor, calculating the braking mass of each wheel according to the current signal fed back by the piezoelectric pressure sensor at each wheel, and calculating the proportion of the load on each wheel, allocating braking force to a single wheel according to the braking force ratio, and judging whether the single wheel needs to be supplemented with braking force by the wire-controlled brake system according to whether the maximum electric braking force that can be applied by the single wheel is greater than the braking force required by the single wheel.

[0004] However, since the motor is an important driving unit and usually belongs to a different manufacturer than the mechanical wire control brake system, the coordinated control of the two requires a lot of matching work. The above patent only supplements the braking force by a simple superposition method, and requires that the braking force of each wheel can be independently controlled. This is not only a major challenge for the transformation and upgrading of the existing hydraulic brake system, but also greatly changes the braking characteristics of the original vehicle, resulting in low recovery efficiency and easy to cause vehicle instability. Summary of the invention

[0005] The present invention provides an equivalent braking force control method for a wire-controlled brake system of a new energy commercial vehicle, so as to solve the shortcomings of the existing commercial vehicle braking force control that cannot coordinate the distribution of hydraulic braking force and electric braking force, changes the braking characteristics of the original vehicle, has low recovery efficiency, and easily causes vehicle instability.

[0006] The present invention adopts the following technical solution: A method for controlling an equivalent braking force of a wire-controlled brake system of a new energy commercial vehicle comprises the following steps: S01. Obtaining the braking force and braking force distribution coefficient under different braking intensities under pure hydraulic braking of the original vehicle; S02. Evaluate the motor braking capability of the vehicle based on the vehicle status information, and calculate the maximum braking force that can be provided by the front and rear motor brakes in combination with the estimated vehicle mass. F e_max ; S03. Calculate / look up the required equivalent braking force based on the target brake opening percentage ; S04, according to the principle of electric braking priority, the equivalent braking force Decomposition into required electric braking force and required hydraulic braking force ,The braking force required by the vehicle is provided by the electric braking force first, and the insufficient electric braking force is supplemented by the hydraulic braking force; S05, the required electric braking force According to the pre-allocation coefficient Distributed to the front and rear motors; if hydraulic braking is needed to supplement the braking force, the hydraulic braking system itself is also distributed according to the coefficient Distributes hydraulic braking force to the front and rear wheels.

[0007] In a preferred embodiment, the braking force in step S01 includes the total braking force of the commercial vehicle , front axle braking force and rear axle braking force ,in: (1); (2); (3).

[0008] In a preferred embodiment, the equivalent braking force in step S04 is Electric Braking Force on Demand , Required hydraulic braking force The relationship is: (4).

[0009] In a preferred embodiment, in the above step S05, the front and rear motors are allocated front and rear motor forces respectively. , ,in: (5), (6) When hydraulic braking is engaged, the front and rear hydraulic braking forces allocated to the front and rear wheels are , ,in: (7), (8); and: (9), (10).

[0010] Furthermore, the equivalent braking force control method of the wire control brake system of a new energy commercial vehicle of the present invention further includes step S06: during braking, the front and rear axle loads are significantly transferred, and the front and rear motors are coordinated and controlled according to the axle load transfer amount, and the braking force distribution of the front and rear motors is adjusted. The front and rear motor braking forces after the axle load transfer are respectively , ,in: (11), (12); where z is the braking intensity, h g is the height of the car's center of mass from the ground, G For vehicle weight, L is the wheelbase.

[0011] It can be seen from the above description of the present invention that, compared with the prior art, the present invention has the following advantages: 1. The present invention is based on the method of equivalent braking force. Under the same braking intensity request of the intelligent driving system, the total braking force output by the compound braking is consistent with that of pure mechanical braking. At the same time, the chassis domain controller coordinates and controls the hydraulic braking and electric braking. Electric braking force is used first during braking, and the braking force of the front and rear motors is distributed according to the pre-allocated coefficient. If the electric braking force does not meet the braking demand, the insufficient part is controlled by the hydraulic braking force. By adopting this method, there is no need to modify the braking system, and the intelligent driving system does not need to be re-matched. It only needs to flexibly and quickly match the vehicle's wire control braking function through the intelligent chassis, which reduces a lot of calibration work for commercial vehicle compound braking and shortens the development cycle. At the same time, the increased electric braking energy recovery effectively increases the driving range and speeds up the response speed of the braking system. After the vehicle wire control is upgraded, the braking characteristics of the original vehicle are not changed, and the driver's driving habits and braking feeling are not changed.

[0012] 2. The present invention coordinates the control of hydraulic braking and electric braking through the chassis domain controller. When the front and rear axle loads are significantly transferred during braking, the braking force of the front and rear motors is adjusted according to the load transfer amount, thereby ensuring the stable distribution of braking force between the front and rear axles, avoiding vehicle instability caused by simple superposition of electric braking, and effectively improving the braking stability of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural block diagram of the equivalent braking force system of the present invention.

[0014] Figure 2 The figure is a flow chart of the method of the present invention.

[0015] Figure 3 This is a schematic diagram of braking force distribution according to the present invention. DETAILED DESCRIPTION

[0016] The specific implementation of the present invention is described below with reference to the accompanying 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, they are not described in detail below.

[0017] A method for controlling the equivalent braking force of a wire-controlled brake system for a new energy commercial vehicle is based on an equivalent braking force system. Figure 1 The equivalent braking force system includes the intelligent chassis domain controller, the motor system, the hydraulic braking system, and the front and rear wheels of the vehicle. The hydraulic braking system is installed at the rear axle of the new energy commercial vehicle, and the intelligent chassis domain controller coordinates and controls the hydraulic braking system and the motor system. The original vehicle braking system of the new energy commercial vehicle includes the vehicle controller VCU, the hydraulic braking system, and the front and rear wheels of the vehicle. Figure 2 The above equivalent braking force control method of the wire control brake system of new energy commercial vehicles specifically includes the following steps: 1. Based on the equivalent braking force method, under the same braking intensity request of the intelligent driving system, the total braking force output by the compound braking is the same as that of pure hydraulic braking. Specifically: S01. Obtain the braking force and braking force distribution coefficient of the original vehicle's pure hydraulic brake at different braking intensities , and store the data in the controller. Among them: (1) In the formula, is the total braking force of the vehicle, , are the front and rear axle braking forces, .but: (2) (3) From the above formulas (1) to (3), we can get the total braking force under a fixed braking intensity: , Braking force distribution coefficient , front axle braking force , rear axle braking force ,like Figure 3 shown.

[0018] S02. Evaluate the motor braking capability of the vehicle in real time based on the vehicle status information, including: motor external characteristic curve, real-time battery charge and discharge power, the anti-drag torque that the rear axle can withstand, etc., and then use the dynamic equation to calculate the maximum braking force that the front and rear motors can provide in combination with the estimated vehicle mass. F e_max .

[0019] S03. Calculate / look up the required equivalent braking force based on the target brake opening percentage .

[0020] 2. The chassis domain controller coordinates and controls the hydraulic brake and the electric brake, giving priority to the electric brake force. The braking force of the front and rear motors is based on the pre-allocated coefficient. At the same time, the front and rear axle loads are obviously transferred during braking. At this time, the chassis domain controller appropriately adjusts the distribution ratio of the front and rear electric brake force according to the axle load transfer to improve vehicle stability. If the electric brake force does not meet the braking requirements, the insufficient part is compensated by the hydraulic brake force. The details are as follows: S04. Decompose the equivalent braking force into the required electric braking force according to the principle of electric braking priority. and required hydraulic braking force The braking force required by the vehicle is provided by electric braking first, and then supplemented by hydraulic braking; where: (4) S05, the required electric braking force According to the pre-allocation coefficient Distributed to the front and rear motors. If hydraulic braking is involved, due to the front and rear braking force distribution coefficient of hydraulic braking The braking force distribution coefficient of the whole vehicle remains unchanged. ;in: (5) (6) (7) (8) (9) (10) In the formula, , Powering the front and rear electric motors, , It is the front and rear hydraulic brake force.

[0021] From the above formulas (4) to (10), the front and rear electric braking forces and hydraulic braking forces under a fixed braking force distribution coefficient can be obtained.

[0022] S06, when braking, the front and rear axle loads are obviously transferred. The front and rear motors are coordinated and controlled according to the amount of axle load transfer. The braking force distribution of the front and rear motors is adjusted to improve the vehicle stability. The front and rear motor braking forces after the axle load transfer are , ,in: (11) (12) Where z is the braking strength, h g is the height of the car's center of mass from the ground, G For vehicle weight, L is the wheelbase.

[0023] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A method for controlling the equivalent braking force of a wire-controlled brake system of a new energy commercial vehicle, characterized in that: The following steps are involved: S01. Obtaining the braking force and braking force distribution coefficient under different braking intensities under pure hydraulic braking of the original vehicle; S02. Evaluate the motor braking capability of the vehicle based on the vehicle status information, and calculate the maximum braking force that can be provided by the front and rear motor brakes in combination with the estimated vehicle mass. F e_max ; S03. Calculate / look up the required equivalent braking force based on the target brake opening percentage ; S04, according to the principle of electric braking priority, the equivalent braking force Decomposition into required electric braking force and required hydraulic braking force ,The braking force required by the vehicle is provided by the electric braking force first, and the insufficient electric braking force is supplemented by the hydraulic braking force; S05, the required electric braking force According to the pre-allocation coefficient Distributed to the front and rear motors; if hydraulic braking is needed to supplement the braking force, the hydraulic braking system itself is also distributed according to the coefficient Distributes hydraulic braking force to the front and rear wheels.

2. The equivalent braking force control method of a wire control brake system for a new energy commercial vehicle according to claim 1, characterized in that: The braking force in step S01 includes the total braking force of the commercial vehicle , front axle braking force and rear axle braking force ,in: (1); (2); (3).

3. The equivalent braking force control method of a brake-by-wire system for a new energy commercial vehicle according to claim 2, characterized in that: The equivalent braking force in step S04 Demand electric braking force , Required hydraulic braking force The relationship is: (4).

4. The equivalent braking force control method of a brake-by-wire system for a new energy commercial vehicle as claimed in claim 3, characterized in that: In step S05, the front and rear motors are allocated with the front and rear motors ... respectively. , ,in: (5), (6) When hydraulic braking is engaged, the front and rear hydraulic braking forces allocated to the front and rear wheels are , ,in: (7), (8); and: (9), (10).

5. The equivalent braking force control method of a wire control brake system for a new energy commercial vehicle as claimed in claim 4, characterized in that: The step S06 is also included: when braking, the front and rear axle loads are obviously transferred, and the front and rear motors are coordinated and controlled according to the axle load transfer amount. By adjusting the braking force distribution of the front and rear motors, the front and rear motor braking forces after the axle load transfer are respectively , ,in: (11), (12); where z is the braking intensity, h g is the height of the car's center of mass from the ground, G For vehicle weight, L For the wheelbase.

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