CN115923740A - A motor-based ABS control method - Google Patents

Abstract

The invention discloses a motor-based ABS control method, which is suitable for an electromechanical brake that uses a motor to generate driving force. The electromechanical brake includes a brake caliper body, a driving mechanism composed of a motor and a reduction A transmission mechanism that converts motion into linear motion; the brake caliper body is provided with friction plates located on both sides of the brake disc, and the friction plates include inner friction plates and outer friction plates; the transmission mechanism is used to rotate the motor output shaft forward and reverse Converted to axial telescopic movement, so as to provide the pressing force of the friction plate and realize the brake return function; the motor is connected with the upper computer through communication; in this method, the upper computer controls the rotation of the output shaft of the motor according to the real-time braking torque required by the vehicle Angle or output torque, so that the clamping force generated between the friction plate and the brake disc changes periodically, and then realizes the ABS function.

Description

A motor-based ABS control method

technical field

The invention relates to the technical field of vehicle braking, in particular to a motor-based ABS control method.

Background technique

Disc brake calipers have been used for a long time in both passenger cars and commercial vehicles. At present, the power transmission medium of traditional disc brake calipers is hydraulic pressure or air pressure. Traditional fuel vehicles use engines to drive hydraulic pumps or air compressors to convert power energy into pressure energy, and then transmit the pressure energy to wheel brake calipers for braking. However, the traditional pneumatic braking system of commercial vehicles transmits the pressure of the compressor to the wheel, and the whole vehicle needs to arrange relatively complex air pipelines, air storage tanks and various control valves. lag time, but also has a large noise problem. The response time of hydraulic braking is shorter than that of pneumatic braking, but it has higher requirements on the sealing of the circuit. Compared with pneumatic braking, hydraulic braking has the advantages of easy operation and easy use of various optimization adjustment devices, but its structure is complex and there are many precision parts in the system, which makes hydraulic braking not widely used in commercial vehicles. At present, it is mainly used on passenger cars.

With the development of new energy vehicles, internal combustion engines are replaced by electric motors. At this stage, both hydraulic brakes and pneumatic brakes of new energy vehicles need to be equipped with electro-hydraulic pumps or electric air compressors on the vehicles to convert electrical energy into pressure energy, and then transmit the pressure energy to the wheels. At the same time, with the advancement of automotive electronic technology, people have higher and higher requirements for vehicle braking performance. Accurate braking control will be the goal of continuous improvement of automotive braking technology. With the advancement of technology, people began to focus on the research of brake-by-wire technology (Brake-By-Wire). The so-called brake-by-wire technology refers to the integration of a series of intelligent control systems to achieve some advanced functions, such as anti-lock brakes. brake system (ABS), traction control system (TCS), electronic stability control system (ESP) and active collision avoidance technology (ACC), etc., the ultimate goal of wire-controlled brake technology is to replace the traditional pneumatic or hydraulic brake system, And then replaced by more advanced electronic technology. As a product of the transition from the traditional pneumatic or hydraulic brake system to the brake-by-wire system, the wire-controlled hydraulic brake system (Electro Hydraulic Brake, referred to as EHB) appeared. Simply put, EHB is to change the traditional hydraulic control system into an electronic brake system. control system, but the brake execution system is still in the hydraulic form, that is, the "hydraulic-controlled hydraulic" mode has been changed to the "electrical-controlled hydraulic" mode. Of course, there can also be a corresponding form of existence for the pneumatic brake system. EHB is only the preliminary research of brake-by-wire technology, and its ultimate goal is to realize the electronic mechanical brake system, that is, EMB. No hydraulic or pneumatic system is needed anymore, it is a purely mechanical braking system that controls the motor through electrical signals.

EMB has obvious advantages, specifically its performance characteristics are as follows:

1. Due to the cancellation of the gas pipeline, the braking response time is greatly reduced, the braking distance is effectively shortened, and the safety of driving is improved.

provides strong protection;

2. Cancel the air compressor, air storage tank and other components, making the layout of the vehicle more flexible;

3. Adjustable brake pedal, no rebound vibration, better comfort and safety;

4. All additional functions can be realized through the control system, such as ABS, TCS, ESP, ACC, etc.;

5. In the future, it can also be connected to the national traffic management system through the Internet of Vehicles system;

It has greater advantages in terms of braking efficiency, response time and braking system cost.

Anti-lock braking system (antilockbrakesystem) referred to as ABS. The function is to automatically control the braking force of the brake when the car is braking, so that the wheel is not locked and is in a state of rolling and sliding (slip rate is about 20%), so as to ensure that the adhesion between the wheel and the ground is at the maximum. .

The development of the ABS system can be traced back to the early 20th century. In the late 1970s, the rapid development of digital electronic technology and large-scale integrated circuits laid a technical foundation for the practical development of ABS systems. Many companies have successively developed various forms of ABS systems. Since the mid-1980s, the ABS system has developed in the direction of high cost performance. Some companies have simplified the structure and system optimization of ABS, and introduced economical ABS devices; some companies have introduced rear-wheel ABS or four-wheel ABS systems suitable for light trucks and passenger and cargo vehicles. These efforts have created conditions for the rapid popularization of ABS. The ABS system is considered to be the most important technical achievement in terms of safety since seat belts are used in automobiles.

Working process: In ABS, a speed sensor is installed on each wheel, and the signal about the speed of each wheel is input into the electronic control device. The electronic control device monitors and judges the motion state of each wheel according to the signals input by each wheel rotation sensor and forms corresponding control instructions. All the hydraulic solenoid valves are not energized and are in the closed state, and the electric pump is not energized to run. The brake pipelines from the brake master cylinder to each brake wheel cylinder are in a communication state, and each brake wheel cylinder to the fluid reservoir The brake pipelines are all in a closed state, and the brake pressure of each brake wheel cylinder will change with the output pressure of the brake master cylinder. At this time, the braking process is exactly the same as that of the conventional braking system.

During the braking process, when the electronic control device judges that a wheel tends to be locked according to the wheel speed signal input by the wheel speed sensor, the ABS enters the anti-lock brake pressure adjustment process. For example, when the electronic control device determines that the right front wheel tends to be locked, the electronic control device energizes the liquid inlet solenoid valve that controls the brake pressure of the right front wheel, so that the right forward liquid solenoid valve turns into a closed state, and the brake master cylinder outputs If the brake fluid no longer enters the right front brake wheel cylinder, the electronic control device will power off both the right forward solenoid valve and the outlet solenoid valve, turn the inlet solenoid valve into the open state, and turn the outlet solenoid valve into the closed state. At the same time, the electric pump is energized to run, and the brake fluid is sent to the brake wheel cylinder. The brake fluid output by the brake master cylinder and the brake fluid pumped by the electric pump pass through the right forward fluid solenoid valve in the open state. Enter the right front brake wheel cylinder, so that the brake pressure of the right front brake wheel cylinder increases rapidly, and the right front wheel starts to decelerate again.

ABS controls the slip rate of the wheel tending to lock within the vicinity of the slip rate of the peak adhesion coefficient by making the braking pressure of the wheel tending to lock go through the maintain-decrease-increase process repeatedly. Corresponding to each brake wheel cylinder, there is a pair of liquid inlet and liquid outlet solenoid valves, which can be controlled by the electronic control device respectively. Therefore, the brake pressure of each brake wheel cylinder can be adjusted independently, so that the four wheels Brake lockup does not occur.

Although the structural forms and working processes of various ABS are not exactly the same, they all prevent the controlled wheels from being locked by braking by adjusting the braking pressure of the wheels tending to lock in an adaptive cycle. All kinds of ABS are the same in the following aspects.

(1) ABS only adjusts the anti-lock brake pressure on the wheels that tend to be locked during the braking process only after the speed of the car exceeds a certain level (such as 5km/h or 8km/h). When the speed of the car is reduced to a certain level by braking, the ABS will automatically stop the adjustment of the anti-lock brake pressure. After that, the braking process of the car equipped with ABS will be the same as that of the conventional braking system, and the wheels will be locked by the brake. Dead to car brake lock. This is because when the speed of the car is very low, the impact of the wheel being locked by the brake on the braking performance of the car is already very small, and to make the car brake and stop as soon as possible, the wheel must be locked.

(2) During the braking process, only when the controlled wheel tends to lock, the ABS will perform anti-lock adjustment on the braking pressure of the wheel tending to lock; when the controlled wheel has not tended to lock , the braking process is exactly the same as that of the conventional braking system.

(3) ABS has a self-diagnosis function, which can monitor the working conditions of the system. Once a fault affecting the normal operation of the system is found, the ABS will be automatically turned off, and the ABS warning light will be lit to send a warning signal to the driver. The car's braking system still works like a regular braking system.

In the latest national standard GB7258-2017 of "Technical Conditions for Motor Vehicle Operation Safety", it is clearly stipulated: "7.2.12 All vehicles (except three-wheel vehicles, five-axle and above special operation vehicles) and trailers with a total mass greater than 3500kg shall be equipped with Compliant anti-lock brakes."

However, the driving force of the EMB electromechanical braking system is no longer provided by hydraulic or air pressure sources, and cannot be realized through the traditional ABS principle. Therefore, it is necessary to re-develop an ABS anti-lock braking system suitable for motor drive.

Contents of the invention

The purpose of the present invention is to provide a motor-based ABS control method to realize the ABS function by using an electro-mechanical braking system.

In order to solve the above technical problems, the present invention provides a technical solution: a motor-based ABS control method, which is suitable for electromechanical brakes that use motors to generate driving force. The electromechanical brakes include a brake caliper body, a The drive mechanism composed of a motor and a reduction mechanism, and a transmission mechanism that converts rotational motion into linear motion; the brake caliper body is provided with friction plates on both sides of the brake disc, and the friction plates include inner friction plates and outer friction plates; the transmission mechanism It is used to convert the positive and negative rotation motion of the motor output shaft into axial telescopic motion, so as to provide the pressing force of the friction plate and realize the brake return function; the motor is connected with the host computer through communication;

In this method, the host computer controls the rotation angle or output torque of the output shaft of the motor according to the real-time braking torque required by the vehicle, so that the clamping force generated by the braking mechanism changes periodically, thereby realizing the ABS function; the rotation angle or output torque of the motor The torque is processed by the upper computer or the electronic control unit of the vehicle controller by processing the wheel speed signal collected by the on-board sensor system in real time, and the parameters including the slip ratio are obtained through calculation, and then obtained through the corresponding control strategy.

According to the above scheme, the motor operates in torque control mode, and the output torque of the motor is switched according to the torque point and frequency required by the host computer, which is converted into the "maintain-decrease-increase" switching of the clamping force, which will tend to lock The slip rate of the wheel is controlled within a certain range of the slip rate of the peak adhesion coefficient.

According to the above scheme, the motor operates in position control mode, and the rotation angle of the motor is switched according to the position point and frequency required by the host computer, which is converted into the "maintain-decrease-increase" switching of the clamping force, which will tend to lock The slip rate of the wheel is controlled within a certain range of the slip rate of the peak adhesion coefficient.

According to the above scheme, the switching frequency of the motor at two torque values or position points can reach more than 50 times per second.

According to the above scheme, the transmission mechanism includes a screw shaft connected to the output shaft of the motor, a screw nut is arranged on the screw shaft, and a push block is fixed on the screw nut, and the push block is connected with the internal friction plate; the rotation of the output shaft of the motor drives the screw The rotation of the shaft makes the screw nut and the push block move in a straight line, thereby changing the distance between the inner friction plate and the outer friction plate, or changing the friction force between the friction plate and the brake disc.

A motor controller for an electro-mechanical brake is used to implement the motor-based ABS control method described above when controlling a driving mechanism.

A new energy vehicle adopts the motor controller of the above-mentioned electromechanical brake.

A computer-readable storage medium, characterized in that it stores a computer program, and the computer program is invoked by a motor controller to implement the motor-based ABS control method according to any one of claims 1 to 5.

The beneficial effects of the present invention are:

1. The present invention provides a new ABS function realization method, which converts the torque of the motor into the clamping force of the brake mechanism through the transmission mechanism, and controls the torque or position of the motor to undergo rapid periodic changes, thereby realizing ABS function.

2. In the torque control or position control mode, when the ABS is triggered, the high-frequency switching execution of the electronic mechanical braking system is controlled according to the locked-rotor torque point given by the host computer or the position point of the motor output shaft, so that the slippage of each wheel is stabilized at the minimum. Optimum brake slip ratio improves the adaptability of ABS function.

Description of drawings

FIG. 1 is a schematic structural diagram of an electromechanical brake according to an embodiment of the present invention.

In the figure: In the figure: 1-caliper body, 2-push block, 3-screw nut, 4-screw shaft, 5-thrust bearing, 6-shaft sleeve, 7-drive mechanism, 8-caliper bracket, 9- Brake disc, 10-outer friction plate, 11-inner friction plate.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Apparently, the described embodiments are some of the embodiments of the present disclosure, not all of them. Based on the described embodiments of the present disclosure, all other embodiments obtained by persons of ordinary skill in the art without creative effort fall within the protection scope of the present disclosure.

A motor-based ABS control method, which is suitable for electromechanical brakes that use motors to generate driving force, see Figure 1, the brake caliper body, the drive mechanism 7 consisting of a motor and a reduction mechanism, converts rotational motion into linear motion The transmission mechanism; wherein the brake caliper body is provided with friction plates located on both sides of the brake disc, and the friction plates include inner friction plates 11 and outer friction plates 10; the transmission mechanism is used to convert the positive and negative rotational motion of the motor output shaft into the Telescopic movement, so as to provide the pressing force of the friction plate and realize the brake return function; the motor is connected with the upper computer by communication;

In this method, the host computer controls the rotation angle or output torque of the output shaft of the motor according to the real-time braking torque required by the vehicle, so that the clamping force generated between the friction plate and the brake disc changes periodically, thereby realizing the ABS function; The rotation angle or output torque of the vehicle is processed by the upper computer or the electronic control unit of the vehicle controller through the real-time collection of the wheel speed signal of the on-board sensor system, and the parameters including the slip rate are obtained through calculation, and then through the corresponding control strategy get.

Further, the motor is a DC servo motor; the motor described in the present invention is not limited to the DC servo motor in this embodiment, and other control motors can be realized.

Further, the reduction mechanism is a planetary reduction mechanism; the reduction mechanism in the present invention is not limited to the planetary reduction mechanism in this embodiment, and may also be a gear box, a worm gear or other reduction mechanisms.

Further, the motor operates in torque control mode, and the output torque of the motor is switched according to the torque point and frequency required by the host computer, which is converted into the "maintain-decrease-increase" switching of the clamping force, which will tend to lock the wheel The slip rate is controlled within a certain range of the peak adhesion coefficient slip rate.

Further, the motor operates in position control mode, and the rotation angle of the motor is switched according to the position point and frequency required by the host computer, which is converted into the "maintain-decrease-increase" switching of the clamping force, which will tend to lock the wheel The slip rate is controlled within a certain range of the peak adhesion coefficient slip rate.

Furthermore, the switching frequency of the motor at two torque values or position points can reach more than 50 times per second, so that the braking frequency of ABS based on the motor can reach the braking frequency of conventional disc brakes.

Further, the transmission mechanism is a ball screw structure connected with the output shaft of the motor, and the braking mechanism includes an inner friction plate 11 driven by the motor and an outer friction plate 10 fixedly arranged; wherein the screw shaft 4 is connected to the output shaft of the motor through a key , the screw nut 3 on the screw shaft 4 is fixed with a push block 2, between the push block 2 and the inner friction plate 11, or between the push block 2 and the caliper body 1, there is an anti-rotation mechanism, so as to ensure that the push block 2 only move along the axis. The transmission mechanism of the present invention is not limited to the ball screw pair in this embodiment, and can also be other threaded screws, wedges, crank connecting rods, worm gears, racks and pinions, eccentric wheels/cams, half teeth plus springs And other transformation mechanical structures.

A motor controller for an electro-mechanical brake is used to implement the motor-based ABS control method described above when controlling a driving mechanism.

A new energy vehicle adopts the motor controller of the above-mentioned electromechanical brake.

A computer-readable storage medium, which stores a computer program, and the computer program is invoked by a motor controller to implement the motor-based ABS control method described above.

The above is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process conversion made by using the description of the present invention and the contents of the accompanying drawings, or directly or indirectly used in other related technologies fields, all of which are equally included in the scope of patent protection of the present invention.

Claims (8)

1. A motor-based ABS control method, characterized in that: the method is applicable to an electro-mechanical brake that generates a driving force with a motor, and the electro-mechanical brake includes a brake caliper body, a driving mechanism composed of a motor and a reduction mechanism, A transmission mechanism that converts rotational motion into linear motion; the brake caliper body is provided with friction plates located on both sides of the brake disc, and the friction plates include inner friction plates and outer friction plates; the transmission mechanism is used to convert the positive and negative sides of the motor output shaft Rotational motion is converted into axial telescopic motion, thereby providing the pressing force of the friction plate and realizing the brake return function; the motor is connected with the upper computer through communication; In this method, the host computer controls the rotation angle or output torque of the output shaft of the motor according to the real-time braking torque required by the vehicle, so that the clamping force generated between the friction plate and the brake disc changes periodically, thereby realizing the ABS function; The rotation angle or output torque of the vehicle is processed by the upper computer or the electronic control unit of the vehicle controller through the real-time collection of the wheel speed signal of the on-board sensor system, and the parameters including the slip rate are obtained through calculation, and then through the corresponding control strategy get. 2. The motor-based ABS control method according to claim 1, characterized in that: the motor operates in a torque control mode, the output torque of the motor is switched according to the torque point and frequency required by the host computer, and converted into the clamping force The "maintain-decrease-increase" switch controls the slip rate of the wheel tending to lock within a certain range of the peak adhesion coefficient slip rate. 3. The motor-based ABS control method according to claim 1, characterized in that: the motor operates in a position control mode, and the rotation angle of the motor is switched according to the position point and frequency required by the host computer, and converted into the clamping force The "maintain-decrease-increase" switch controls the slip rate of the wheel tending to lock within a certain range of the peak adhesion coefficient slip rate. 4. The motor-based ABS control method according to claim 2 or 3, characterized in that the switching frequency of the motor at two torque values or position points can reach more than 50 times per second. 5. The motor-based ABS control method according to claim 1, characterized in that: the transmission mechanism includes a screw shaft connected to the output shaft of the motor, the screw shaft is provided with a screw nut, and the screw nut is fixed with a push block , the push block is connected with the inner friction plate; the rotation of the output shaft of the motor drives the screw shaft to rotate, so that the screw nut and the push block move in a straight line, and then the distance between the inner friction plate and the outer friction plate changes, or the friction plate and the system The friction between the discs changes. 6. A motor controller for an electromechanical brake, characterized in that it is used to implement the motor-based ABS control method according to any one of claims 1-5 when controlling the driving mechanism. 7. A new energy vehicle, characterized in that: the motor controller of the electronic mechanical brake according to claim 6 is adopted. 8. A computer-readable storage medium, characterized in that: it stores a computer program, and the computer program is called by the motor controller to implement the motor-based ABS control method according to any one of claims 1 to 5 .

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