Brake-by-wire system and dragging torque maneuvering control method thereof

Abstract

The invention relates to the field of vehicle control methods, in particular to a brake-by-wire system and a dragging torque maneuvering control method thereof. The method includes the following steps that firstly, the opening degree of an accelerator pedal is obtained; 2, analyzing a driving intention according to the opening degree of the accelerator pedal; and 3, through the recognized driving intention, the brake-by-wire system sends a corresponding dragging torque control instruction, and the dragging torque control instruction drives a friction plate to change the distance between the friction plate and a brake disc. According to the method, the opening degree of the accelerator pedal and the change rate of the opening degree are detected, the driving intention of a driver is judged through an algorithm, then the distance between the friction plate and the brake disc is autonomously adjusted, the dragging torque is reduced or increased, and preparation is made for subsequent braking or acceleration.

Description

Technical Field

[0001] The present invention relates to the field of vehicle control methods, and in particular to a brake-by-wire system and a drag torque maneuvering control method thereof. Background Art

[0002] With the increasing application of new energy vehicles, driving range and energy consumption levels are receiving more and more attention. When the driver wants the vehicle to accelerate, the reduction of the drag torque of the braking system or even zero drag will undoubtedly have a positive impact on reducing friction loss and increasing driving range. At the same time, braking performance is an important performance indicator related to safety. When the driver is about to brake, a fast braking response speed is still indispensable.

[0003] As the electronic mechanical brake system (EMB) becomes the mainstream of the development of wire-controlled brake systems, the above-mentioned requirements of zero drag and high response speed can be met at the same time; the electronic mechanical brake system is a wire-controlled device that decouples the brake actuator and the driver's pedal. It drives the transmission mechanism through a motor to push the friction pad on the brake against the brake disc to generate sufficient braking force, thereby obtaining the desired braking torque. An independent electronic mechanical brake will be installed on each wheel, and the wire-controlled chassis domain controller integrates and controls four electronic mechanical brakes to achieve the braking function.

[0004] However, the control method for the electronic mechanical brake system in the prior art has the problems of low sensitivity and slow response speed. Summary of the invention

[0005] The purpose of the present invention is to provide a brake-by-wire system and a drag torque maneuvering control method thereof, so as to solve the problems of low sensitivity and slow response speed in the control method for the electronic mechanical brake system in the prior art.

[0006] The technical solution of the present invention is: a method for controlling the drag torque of a wire control brake system, comprising the following steps:

[0007] Step 1: Obtain the accelerator pedal opening;

[0008] Step 2, analyzing driving intention according to the accelerator pedal opening;

[0009] Step 3: by identifying the driving intention, the brake-by-wire system sends a corresponding drag torque control instruction, and the drag torque control instruction drives the friction plate to change the distance from the brake disc.

[0010] Preferably, the step 2 includes the following process:

[0011] Set the acceleration confirmation threshold P of the accelerator pedal opening acc, the actual value P of the accelerator pedal opening at any time T ;

[0012] Compare P T With P acc , and make the following judgment:

[0013] If P T Less than P acc , then the driving intention is judged to be coasting;

[0014] If P T Greater than P acc , then set the accelerator pedal opening after time period T1 T+T1 , and compare P T+T1 With P T ;

[0015] If P T+T1 Greater than P T , then the driving intention is judged to be accelerating;

[0016] If P T+T1 Less than P T , then set the change rate of the accelerator pedal opening DP T , and the emergency threshold DP brk ; Compare DP T With DP brk , and make the following judgment:

[0017] If there is DP T Greater than DP brk , vehicle stability margin < 1, ADAS system sends out any of the following braking preparation signals, the driving intention is judged to be braking preparation;

[0018] If DP T Less than DP brk , the driving intention is judged to be slow driving.

[0019] Preferably, the drag torque control instruction includes a default drag torque control instruction, a zero drag torque control instruction, a high drag torque control instruction and a maneuvering drag torque control instruction;

[0020] Furthermore, when the driving intention is to coast, the brake-by-wire system sends a default drag torque control instruction;

[0021] When the driving intention is to accelerate, the brake-by-wire system sends a zero-drag torque control command;

[0022] When the driving intention is to prepare for braking, the brake-by-wire system sends a high drag torque control command;

[0023] When the driving intention is to slow down, the brake-by-wire system sends a maneuvering drag torque control command.

[0024] Preferably, the friction plate has a reference position S0 relative to the brake disc;

[0025] When receiving the default drag torque control instruction, the friction plate moves a distance S1 in a direction away from the brake disc based on the reference position S0;

[0026] When receiving the zero drag torque control command, the friction plate moves a distance S1+S2 away from the brake disc based on the reference position S0;

[0027] When a high drag torque control command is received, the friction plate moves S3 toward the brake disc based on the reference position S0;

[0028] When receiving the maneuvering drag torque control command, the friction plate moves a distance SX in a direction close to or away from the brake disc based on the reference position S0.

[0029] Preferably, the SX is between S3 and S1+S2 and is T Directly proportional.

[0030] A wire-controlled brake system comprises a wire-controlled chassis controller and an electronic mechanical brake, which is used to reflect an accelerator pedal signal and a brake pedal signal input by a driver.

[0031] The electronic mechanical brakes are distributed and arranged to include a left front wheel electronic mechanical brake, a left rear wheel electronic mechanical brake, a right front wheel electronic mechanical brake, and a right rear wheel electronic mechanical brake;

[0032] The accelerator pedal signal and the ADAS brake request signal are obtained through the CAN network;

[0033] The wire-controlled chassis controller calculates the braking force requirement according to the brake pedal signal and sends it to the electronic mechanical brake for execution, so as to brake and decelerate the vehicle; the wire-controlled chassis controller has a driving intention recognition module and a drag torque control module.

[0034] Compared with the prior art, the advantages of the present invention are:

[0035] The present invention will detect the opening degree of the accelerator pedal and the rate of change of the opening degree, determine the driver's driving intention through an algorithm, and then autonomously adjust the distance between the friction plate and the brake disc to reduce or increase the drag torque, thereby preparing for subsequent braking or acceleration. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0037] Figure 1 This is a schematic diagram of the architecture of a wire control brake system according to the present invention;

[0038] Figure 2 A schematic diagram of a drag torque maneuvering control method for a wire control brake system according to the present invention;

[0039] Figure 3 A flow chart of a drag torque maneuvering control method for a wire control brake system according to the present invention;

[0040] Figure 4 This is a structural diagram of the braking system of the present invention;

[0041] Figure 5 The SX and piston travel distance and DP of the present invention are T Function relationship diagram of ;

[0042] Among them: 1. brake disc, 2. friction plate, 3. piston, 4. motor. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below in conjunction with specific embodiments:

[0044] like Figure 1 As shown, a wire control brake system includes a wire control chassis controller and an electromechanical brake, which is used to reflect the accelerator pedal signal and the brake pedal signal input by the driver.

[0045] Among them, the electronic mechanical brakes are distributed, including a left front wheel electronic mechanical brake, a left rear wheel electronic mechanical brake, a right front wheel electronic mechanical brake, and a right rear wheel electronic mechanical brake.

[0046] The accelerator pedal signal and ADAS brake request signal are obtained through the CAN network.

[0047] The main function of the wire-controlled chassis controller is to calculate the braking force requirement based on the brake pedal signal and send it to the four electronic mechanical brakes to execute the braking and deceleration of the vehicle. It includes the driving intention recognition module and the drag torque control module.

[0048] Combination Figure 2 and Figure 3 As shown, in this embodiment, a method for controlling the drag torque of a wire control brake system is provided, comprising the following steps:

[0049] Step 1: Get the accelerator pedal opening.

[0050] Step 2: Analyze the driver's driving intention according to the accelerator pedal opening, including coasting, accelerating, braking preparation or slowing down.

[0051] Step 3: By identifying the driving intention, the brake-by-wire system sends a corresponding drag torque control instruction, and the drag torque control instruction drives the vehicle as follows: Figure 4 The friction lining 2 shown changes its distance from the brake disk 1 .

[0052] The above steps are used to detect only the driver's control of the accelerator pedal, identify the driver's next operation (driving intention), and control the distance between the friction plate 2 and the brake disc 1 in advance, so as to prepare for the driver's next operation. For example: when the driver is ready to accelerate through the above steps, there is no drag torque between the friction plate 2 and the brake disc 1, thereby increasing the acceleration performance; when it is analyzed that the driver's driving intention is to prepare for braking, before the driver steps on the brake pedal, the friction plate 2 contacts the brake disc 1 in advance, exerting a certain braking force, thereby making the subsequent braking response faster.

[0053] The following are the specific implementation steps of this application:

[0054] Step 2 includes the following process:

[0055] Get the accelerator pedal opening.

[0056] Analyzing driving intention according to the accelerator pedal opening includes the following specific steps.

[0057] Set the acceleration confirmation threshold P of the accelerator pedal opening acc , the actual value P of the accelerator pedal opening at any time T .

[0058] Compare P T With P acc , and make the following judgment:

[0059] If P T Less than P acc , it means that the accelerator pedal is in a lightly depressed state, and the driving intention can be judged as coasting.

[0060] If P T Greater than P acc , further judgment is required:

[0061] Set the accelerator pedal opening angle P after the time period T1 has passed T+T1 , and compare P T+T1 With P T .

[0062] If P T+T1 Greater than P T , it means that the driver's stepping on the accelerator pedal has increased, and it can be judged that the driving intention is to accelerate.

[0063] If P T+T1Less than P T , it means that the driver's stepping on the accelerator pedal begins to decrease, so the following steps need to be performed:

[0064] Set the accelerator pedal opening rate DP T And the emergency threshold DP brk ; Change rate DP T It is used to reflect the speed at which the driver lifts the accelerator pedal. T With DP brk Compare and make the following judgments based on the comparison results:

[0065] If there is DP T Greater than DP brk , indicating that the driver lifted the accelerator pedal very quickly, and the driving intention can be judged as braking preparation. It should be noted that if other vehicle systems detect that the vehicle stability margin is less than 1, or the ADAS system sends a braking preparation signal, the driving intention can also be judged as braking preparation. That is, there is a DP T Greater than DP brk , vehicle stability margin < 1, and the ADAS system sends a braking preparation signal, the driving intention can be judged as braking preparation.

[0066] If DP T Less than DP brk , the driving intention is judged to be slow driving.

[0067] The above judgment method can judge the driver's driving intention by detecting the state of the accelerator pedal.

[0068] The drag torque control module selects the corresponding drag torque command according to the received driving intention and sends it to the electronic mechanical brake for execution.

[0069] Specifically, the drag torque command includes a default drag torque control command, a zero drag torque control command, a high drag torque control command, and a maneuvering drag torque control command.

[0070] When the driving intention is to coast, a default drag torque control command is sent.

[0071] When the driving intention is to accelerate, a zero-drag torque control command is sent.

[0072] When the driving intention is to prepare for braking, a high drag torque control command is sent.

[0073] When the driving intention is to slow down, a maneuvering drag torque control command is sent.

[0074] The above-mentioned different drag torque commands are realized by changing the distance between the friction plate 2 and the brake disc 1 .

[0075] like Figure 4 As shown in the structure diagram of the electronic mechanical brake, the piston 3 pushes the friction plate 2 to move closer to the brake disc 1 under the drive of the motor 4. Before the friction plate 2 contacts the brake disc 1, the motor 4 that drives the piston 3 to operate only needs to overcome the friction between the piston 3 and the cylinder body, so the current required at this time is very small.

[0076] After reaching the contact point, the force on the piston 3 increases, causing the current of the motor 4 to rise rapidly. Therefore, when it is detected that the current of the motor 4 exceeds a certain threshold, it can be reversely inferred that the friction plate 2 has reached the contact point, and this position is set as the reference position S0.

[0077] When receiving the default drag torque control command, the piston 3 moves a distance S1 away from the friction plate 2 based on the reference position S0. Because the end surface of the brake disc 1 is not completely flat and has runout, after the piston 3 moves a distance S1, when the vehicle is running, the brake disc 1 rotates and part of its end surface contacts the friction plate 2, thus bringing a certain default drag torque.

[0078] When receiving the zero drag torque control command, the piston 3 moves a distance S1+S2 away from the friction plate 2 based on the reference position S0, so that a gap is maintained between the friction plate 2 and any part of the end surface of the brake disc 1, thereby eliminating the drag torque.

[0079] When receiving the high drag torque control command, the piston 3 moves a distance S3 toward the friction plate 2 based on the reference position S0 or makes the clamping force reach the threshold value, so that the friction plate 2 is in close contact with the brake disc 1 and the maximum braking force is applied.

[0080] When receiving the maneuvering drag torque control command, the piston 3 moves a distance SX toward or away from the friction plate 2 based on the reference position S0 to achieve maneuvering control. Figure 5 As shown, SX is between S3 and S1+S2 and is connected to DP T Directly proportional.

[0081] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the scope of protection of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the attached claims rather than the above description, and it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention.

Claims

1. A method for controlling the drag torque of a wire control brake system, characterized in that: The steps include: Step 1: Obtain the accelerator pedal opening; Step 2, analyzing driving intention according to the accelerator pedal opening; Step 3: by identifying the driving intention, the brake-by-wire system sends a corresponding drag torque control instruction, and the drag torque control instruction drives the friction plate to change the distance from the brake disc.

2. The method for controlling the drag torque of a brake-by-wire system according to claim 1, characterized in that: The step 2 includes the following process: Set the acceleration confirmation threshold P of the accelerator pedal opening acc , the actual value P of the accelerator pedal opening at any time T ; Compare P T With P acc , and make the following judgment: If P T Less than P acc , then the driving intention is judged to be coasting; If P T Greater than P acc , then set the accelerator pedal opening after time period T1 T+T1 , and compare P T+T1 With P T ; If P T+T1 Greater than P T , then the driving intention is judged to be accelerating; If P T+T1 Less than P T , then set the change rate of the accelerator pedal opening DP T , and the emergency threshold DP brk ; Compare DP T With DP brk , and make the following judgment: If there is DP T Greater than DP brk , vehicle stability margin < 1, ADAS system sends out any of the following braking preparation signals, the driving intention is judged to be braking preparation; If DP T Less than DP brk , the driving intention is judged to be slow driving.

3. The method for controlling the drag torque of a brake-by-wire system according to claim 2, characterized in that: The drag torque control instructions include a default drag torque control instruction, a zero drag torque control instruction, a high drag torque control instruction and a maneuvering drag torque control instruction; Furthermore, when the driving intention is to coast, the brake-by-wire system sends a default drag torque control instruction; When the driving intention is to accelerate, the brake-by-wire system sends a zero-drag torque control command; When the driving intention is to prepare for braking, the brake-by-wire system sends a high drag torque control command; When the driving intention is to slow down, the brake-by-wire system sends a maneuvering drag torque control command.

4. The method for controlling the drag torque of a brake-by-wire system according to claim 3, characterized in that: The friction plate has a reference position S0 relative to the brake disc; When receiving the default drag torque control instruction, the friction plate moves a distance S1 in a direction away from the brake disc based on the reference position S0; When receiving the zero drag torque control command, the friction plate moves a distance S1+S2 away from the brake disc based on the reference position S0; When a high drag torque control command is received, the friction plate moves S3 toward the brake disc based on the reference position S0; When receiving the maneuvering drag torque control command, the friction plate moves a distance SX in a direction close to or away from the brake disc based on the reference position S0.

5. The method for controlling the drag torque of a brake-by-wire system according to claim 4, characterized in that: The SX is between S3 and S1+S2 and is connected to DP T Directly proportional.

6. A brake-by-wire system, characterized in that: Includes a drive-by-wire chassis controller and an electromechanical brake; used to reflect the accelerator pedal signal and brake pedal signal input by the driver. The electronic mechanical brakes are distributed and arranged to include a left front wheel electronic mechanical brake, a left rear wheel electronic mechanical brake, a right front wheel electronic mechanical brake, and a right rear wheel electronic mechanical brake; The accelerator pedal signal and the ADAS brake request signal are obtained through the CAN network; The wire-controlled chassis controller calculates the braking force requirement according to the brake pedal signal and sends it to the electronic mechanical brake for execution, so as to brake and decelerate the vehicle; the wire-controlled chassis controller has a driving intention recognition module and a drag torque control module.

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