An electromechanical brake-by-wire device and a control method thereof

Abstract

The present application relates to a kind of electronic mechanical line control brake device and its control mode, applied in the field of automobile line control.The present application adopts double motor structure, first motor is used for driving brake, second motor is used for parking brake, when first motor and its transmission mechanism are damaged, it can also be used for driving brake;A kind of wedge mechanism is used to convert rotary motion into linear motion and realize torque effect, the mechanism has switchable three kinds of torque coefficient, first torque coefficient and second torque coefficient are used for driving brake, third torque coefficient is used for parking brake, through the switching of multiple torque coefficient, brake gap can be more quickly eliminated, control precision can be improved under lower brake force demand, when brake force demand is larger, sufficient brake force can also be guaranteed to obtain;Through wear detection system, the wear condition between brake friction pad and brake disc can be detected in real time to correct the switching condition of different torque coefficient, when wear is too serious, driver will be prompted to replace.

Description

Technical Field

[0001] This invention belongs to the field of automotive brake-by-wire technology, and particularly relates to an electromechanical brake-by-wire device and its control method. Background Technology

[0002] Drive-by-wire technology originated in the aviation field. With the rapid development of sensor technology and network communication technology, drive-by-wire technology has also begun to appear in the automotive field. Its application in the chassis field has made high-level autonomous driving possible. Drive-by-wire chassis eliminates many complex mechanical connections and hydraulic and pneumatic structures in traditional chassis. While improving transmission efficiency, it also reduces the difficulty of integrated control and active control of modules such as braking, steering, driving, and shifting. It is the mainstream direction of current automotive chassis technology.

[0003] Braking by steer is an important component of automotive steerable chassis. Compared to traditional braking systems, it has advantages such as fast response speed, simple structure, small weight, and easy integration of auxiliary braking functions. Current braking by steer is mainly divided into two types: electro-hydraulic braking and electro-mechanical braking. Electro-mechanical braking eliminates all hydraulic lines and uses electronic actuators, achieving complete decoupling between the brake pedal and the brake actuator. This better reflects the advantages of braking by steer systems in terms of response speed, ease of functional integration, and structural complexity.

[0004] The German company VDO proposed an electronic wedge brake using a wedge mechanism. The wedge mechanism of this device consists of two wedge blocks with multiple wedge surfaces and multiple rollers between the two wedge blocks. A screw and nut mechanism is used to convert the rotational motion of the motor into linear motion, which pushes one wedge block with multiple wedge surfaces to move laterally. The other wedge block is fixed on the clamp body. Under the action of the wedge surfaces and rollers, the lateral wedge block moves longitudinally at the same time to press the brake disc to achieve braking. This brake has a good self-force amplification effect, but the force amplification coefficient is not adjustable and is affected by the friction coefficient between the wedge block and the brake disc. It is difficult to control, has poor control accuracy, and may also jam. Summary of the Invention

[0005] This invention designs an electromechanical linear control braking device and its control method. This electromechanical brake-by-wire device employs a dual-motor structure. The first motor in the first power unit is used for service braking, and the second motor in the second power unit is used for parking braking. The dual-motor structure provides additional mechanical redundancy for the electromechanical brake-by-wire device. Even if the first motor and its transmission mechanism are damaged, service braking can still be performed via the second motor. The device transmits motor torque through a wedge-shaped transmission mechanism with switchable multiple torque amplification coefficients, converting rotational motion into linear motion to achieve braking. The circular wedge-shaped mechanism avoids jamming. According to the control method designed in this invention, different braking modes can be switched based on the driver's braking force requirements and the wear condition of the brake disc and brake friction pads. Different braking modes have different torque amplification coefficients, stroke conversion coefficients, and maximum strokes. Switching between different braking modes can quickly eliminate brake gaps, improve braking response speed, maintain higher control accuracy when the required braking force is low, and ensure sufficient braking force when the required braking force is high. The wear detection system can detect the wear condition between the brake friction pads and brake discs in real time to correct the switching conditions of different torque amplification coefficients. When the wear is too severe, the driver will be prompted to replace the brake pads.

[0006] According to a first aspect of the present invention, an electromechanical linear control braking device is designed.

[0007] The electromechanical wire-controlled braking device includes a brake caliper body, two brake friction pads, a brake disc, a first power unit, a second power unit, a first drive shaft, a second drive shaft, a wedge-shaped transmission mechanism, a first clutch, a second clutch, a slewing bearing, a piston, a pressure sensor, a rotary encoder, a return spring, and a thrust bearing. The brake caliper body comprises a first brake caliper body, a second brake caliper body, and a third brake caliper body, all three being fixed together by fastening nuts. The first and second power units each consist of a motor and a planetary gear set for speed reduction and torque increase. The first power unit is located outside the brake caliper body and is fixed to the third brake caliper body by fastening nuts, driving the first drive shaft to rotate. The second power unit is located... Inside the brake caliper body, a fastening nut secures it to the piston, allowing the second drive shaft to rotate. A protruding limiting block is located on the outside of the piston. A matching groove is located inside the first brake caliper body, allowing the piston to move longitudinally along the groove but preventing rotation. One end of a return spring presses against the outside of the piston, while the other end is placed in the mounting hole of the first brake caliper body. Both power units can drive the wedge-shaped transmission mechanism to extend and retract longitudinally, thereby pushing the piston and brake friction pads to achieve braking. The wedge-shaped transmission mechanism can operate at three torque multiplication coefficients. A pressure sensor is installed between the piston and the brake friction pad near the piston to measure the pressure between them. A rotary encoder is connected to the first drive shaft to measure its rotation angle.

[0008] Furthermore, the wedge-shaped transmission mechanism consists of a first transmission block, a second transmission block, a third transmission block, a transmission disc, six rollers, and a torsion spring. The first and second transmission blocks are stacked on the first transmission shaft. The first transmission block is located near the piston and has a hole that mates with the first transmission shaft. The two are in an interference fit and can receive the torque transmitted by the first power unit. The second transmission block has a bearing hole and is supported on the first transmission shaft by the slewing bearing. The third transmission block is divided into two identical parts. These two parts are symmetrical about the axis of the wedge-shaped transmission mechanism and are both fixed to the third brake caliper body by fastening nuts. The transmission disc has a hole that mates with the second transmission shaft. The two are in an interference fit and can receive the torque transmitted by the second power unit. The surfaces of the first, second, and third transmission blocks away from the piston are on the same plane. On this plane, the three transmission blocks are supported on the inner wall of the third brake caliper body by the thrust bearing.

[0009] Furthermore, the first, second, and third transmission blocks each have two triangular wedge-shaped grooves on their surfaces near the piston, and the transmission disc has six frustum-shaped roller grooves on its surface away from the piston for placing rollers. The included angle between the axes of the six roller grooves is 60°. The six rollers are placed in these six roller grooves respectively. With the support of the thrust bearing, the six triangular wedge-shaped grooves on the first, second, and third transmission blocks press on the six rollers respectively. At this time, the two inclined surfaces of each triangular wedge-shaped groove can be tangent to the rollers. The included angle between any two of the first, second, and third transmission blocks is also 60°. When the first and second transmission blocks rotate around the axis of the wedge-shaped transmission mechanism and the transmission disc cannot rotate, or when the first and second transmission blocks do not rotate and the transmission disc rotates, the transmission disc will move longitudinally under the pressure of the rollers.

[0010] Furthermore, the same torsion spring placement groove is opened on the surface of the first transmission block near the piston and the surface of the second transmission block away from the piston. The torsion spring is placed in the two torsion spring placement grooves. The spring force of the torsion spring can resist the angle change between the first transmission block and the second transmission block. The torsion spring has a preload force, which makes the second transmission block rotate with it when the first transmission block rotates, and the second transmission block can always press the roller into the roller groove.

[0011] Furthermore, the first clutch includes two friction discs and two corresponding electromagnets. One friction disc and one electromagnet are fixed to the first transmission shaft by a fastening nut, and the other friction disc and the other electromagnet are mounted on the second transmission block by a fastening nut. The two friction discs are adjacent to each other with a small gap between them. The two electromagnets are located on the outside of the two friction discs respectively. When the electromagnets are energized, they attract each other and can push the second transmission block to produce a small longitudinal displacement, thereby eliminating the gap between the two friction discs. The two friction discs are pressed together to transmit the torque generated by the first power unit.

[0012] Furthermore, the second clutch includes an electromagnet, six sliders, and a compression spring. The piston has six slider slots that cooperate with the sliders and a placement slot for placing the electromagnet. The compression spring is placed between the electromagnet and the sliders, pressing the sliders into the slider slots. The transmission disc cannot rotate relative to the piston. When the electromagnet is energized, it attracts the sliders to slide out of the slider slots, and the transmission disc can rotate relative to the piston.

[0013] Furthermore, the triangular wedge grooves on the first, second, and third transmission blocks have different wedge angles. The wedge angle of the triangular wedge groove on the first transmission block is α, the wedge angle of the triangular wedge groove on the second transmission block is β, and the wedge angle of the triangular wedge groove on the third transmission block is γ. The relationship between the three wedge angles is α > β > γ. Rotating the three transmission blocks respectively represents three driving braking modes. By designing the size of the wedge angles, the distances r1, r2, and r3 from the mid-surface of the triangular wedge groove and roller mating part of the three transmission blocks to the center of the transmission block, the friction coefficient μ between the brake disc and the brake friction pad, and the distance R from the brake friction pad to the center of the wheel, the wedge transmission mechanism has three different torque amplification coefficients C1, C2, and C3, as shown in the following formula:

[0014]

[0015] In the formula, T m1 T is the torque generated by the first power unit. m2 The torque T generated by the second power unit b1 T b2 T b3 The braking torque applied to the brake disc under three braking modes is such that the three torque multiplication coefficients satisfy that C1 and C3 are both less than C2.

[0016] Furthermore, the three braking modes correspond to three stroke conversion coefficients S1, S2, and S3, respectively. Each stroke conversion coefficient represents the distance the piston moves longitudinally under a unit transmission shaft rotation angle. S1 and S2 correspond to the distance the piston moves longitudinally under a unit first transmission shaft rotation angle, and S3 corresponds to the distance the piston moves longitudinally under a unit second transmission shaft rotation angle, as shown in the following formula:

[0017]

[0018] In the formula, δ1 represents the clearance coefficient between the first transmission block and the roller in the wedge transmission mechanism, δ2 represents the clearance coefficient between the second transmission block and the roller in the wedge transmission mechanism, and δ3 represents the clearance coefficient between the third transmission block and the roller in the wedge transmission mechanism. These three coefficients are obtained by experiments. Through the design of the parameters in the formula, the three stroke conversion coefficients satisfy S1>S3>S2.

[0019] Furthermore, the three braking modes correspond to three maximum strokes L1, L2, and L3, respectively. The maximum stroke represents the maximum distance that the wedge-shaped transmission mechanism can extend or retract, as shown in the following formula:

[0020]

[0021] In the formula, r g Let b1 be the maximum radius of the roller (95), and b1, b2, and b3 be the maximum widths of the triangular wedge grooves on the three wedge transmission blocks and the mating surfaces of the rollers, respectively. Through parameter design, the three maximum strokes satisfy L3 > L1 > L2. When the vehicle is in the service braking mode with the first transmission block rotating, and the wedge transmission mechanism reaches its maximum stroke L1, the pressure value obtained by the pressure sensor is the preset switching threshold F. s .

[0022] Furthermore, the inner wall of the piston is in direct contact with the surface of the transmission disc near the piston, and there is a frictional fit between them with a coefficient of friction of μ. p Satisfying condition μ p >tan(γ), when the second clutch is disengaged, the wedge transmission mechanism extends under the torque transmitted by the second power unit and the transmission disc, and the transmission disc is self-locked under the support of the third transmission block, so the braking force will not disappear after the second power unit stops rotating.

[0023] According to a second aspect of the present invention, a wear detection method for brake discs and brake friction pads is designed to indicate the wear condition of the two brake friction pads and the brake disc and prompt the driver to perform timely maintenance and replacement. The electronic control unit records the total rotation angle values ​​θ1, θ2, θ3 collected by the rotary encoder when the pressure values ​​obtained by the pressure sensor are F1, F2, F3, and calculates the wear amount Δx. If the required braking force F d <F s Then F1, F2, and F3 are obtained from the following formula:

[0024]

[0025] If the required braking force F d ≥F s Then F1, F2, and F3 are obtained from the following formula:

[0026]

[0027] The wear amount Δx is calculated using the following formula:

[0028] Δx=ε1(θ1S1-x s1 )+ε2(θ2S1-x s2 )+ε3(θ3S1-x s3 )

[0029] In the formula, ε1, ε2, and ε3 are weighting factors, satisfying ε1 + ε2 + ε3 = 1, ε1 < ε2 < ε3. If θ1ε1 is not within the set range (x s1 1.3x s1 If θ2ε2 is not within the set range (x), then ε1 = 0; if θ2ε2 is not within the set range (x), then ε1 = 0. s2 1.3x s2 If θ3ε3 is not within the set range (x), then ε2 = 0. s3 1.3x s3 If ε3 = 0, then x s1 x s1 x s1 These represent the longitudinal displacement values ​​of the piston when pressure values ​​F1, F2, and F3 are reached under unworn conditions. These values ​​were obtained experimentally. When the wear amount Δx exceeds the wear threshold Δx... l At this time, the system will send audible and visual warning signals to the driver through the in-vehicle audio system and instrument panel indicator lights.

[0030] According to a third aspect of the invention, the invention includes a control method for the electromechanical linear braking device.

[0031] The control method of the electromechanical brake-by-wire device includes a service brake control method:

[0032] Step 1) The electronic control unit receives the brake pedal opening from the driver and calculates the required braking force F. d ;

[0033] Step 2) Check whether the first power unit, the first drive shaft, the first transmission block, and the second transmission block are faulty. If any of the above components are faulty, proceed to step 8).

[0034] Step 3) The electronic control unit starts to control the rotation of the first power unit. The first clutch is not energized and is in the disengaged state. The second clutch is not energized and is in the engaged state. At this time, the wedge transmission mechanism works in the first braking mode with a torque amplification coefficient of C1, a stroke conversion coefficient of S1, and a maximum stroke of L1, which quickly overcomes the braking gap and applies braking force.

[0035] Step 4) The electronic control unit performs wear detection. If the wear exceeds the limit, it will issue an audible and visual warning signal to the driver through the in-vehicle audio system and instrument panel indicator lights.

[0036] Step 5) Compare the required braking force F d With switching threshold F s If F d >F s Then proceed to step 7);

[0037] Step 6) The first power unit increases braking force when rotating forward, decreases braking force when rotating in reverse, and maintains braking force when stalled, so that the braking force changes proportionally with the brake pedal opening until the brake pedal opening is 0, and the service braking ends.

[0038] Step 7) When the conditions for switching between the first and second braking modes are met, the first clutch is energized and in the engaged state, and the second clutch is de-energized and in the engaged state. At this time, the wedge transmission structure works in the second braking mode, with a torque amplification coefficient of C2, a stroke conversion coefficient of S2, and a maximum stroke of L2. Return to step 6).

[0039] Step 8) The electronic control unit controls the second power unit to rotate, the second clutch is energized and in the disengaged state. At this time, the wedge transmission mechanism works in the third braking mode, with a torque amplification coefficient of C3, a stroke conversion coefficient of S3, and a maximum stroke of L3.

[0040] Step 9) The second power unit increases braking force when rotating forward, decreases braking force when rotating in reverse, and maintains braking force when stalled, so that the braking force changes proportionally with the brake pedal opening until the brake pedal opening is 0, and the service braking ends.

[0041] The control method for the electromechanical brake-by-wire device includes a parking brake control method:

[0042] Step 1) The driver presses the parking brake button. If the driver presses the brake pedal at this time and maintains the service brake, then proceed to step 2). The electronic control unit controls the second power unit to rotate forward, the second clutch is energized and is in the disengaged state. At this time, the wedge transmission mechanism works in the third braking mode. The piston pushes the two brake friction pads to clamp the brake disc, so that the wheels will not turn when the vehicle is stationary at any slope. Proceed to step 4).

[0043] Step 2) The first power unit maintains a positive torque T d T d The electronic control unit calculates the second clutch based on the brake pedal opening, which is then energized and in the disengaged state. The electronic control unit then controls the second power unit to provide a positive torque T. p The direction of rotation of the first power unit is opposite to that of the second power unit, satisfying |T p|>|T d |;

[0044] Step 3) Determine whether the first transmission block has returned to its initial position based on the first transmission shaft angle value collected by the rotary encoder. That is, the angle between each pair of the three transmission blocks is 60°. If it returns to the initial position, the first clutch is de-energized and is in the disengaged state. The first power unit stops rotating, and the second power unit continues to drive the transmission disc to rotate. At this time, the wedge transmission mechanism works in the third braking mode. The piston pushes the two brake friction pads to clamp the brake disc, so that the wheels will not rotate when the vehicle is stationary at any slope.

[0045] Step 4) The second power unit stops, the second clutch is de-energized, and the piston and transmission disc self-lock to maintain braking force;

[0046] Step 5) The driver presses the parking brake button again, and the electronic control unit controls the second power unit to reverse. After the transmission disc returns to the initial position before the parking brake is applied, the second clutch engages under the action of the compression spring, and the parking brake is released.

[0047] Furthermore, the switching conditions for the first and second braking modes include four sub-conditions:

[0048] Sub-condition 1: The pressure value F collected by the pressure sensor satisfies |F s -(F+kΔx)|<ρ1, kΔx represents the compensation pressure value added due to the wear of the two brake friction pads and brake disc, k is the wear compensation coefficient, obtained through experiments, and ρ1 is the critical pressure difference, obtained through experiments, to minimize pressure fluctuations when switching braking modes;

[0049] Sub-condition 2: The angle value θ collected by the rotary encoder satisfies |L1-θS1|<ρ2, where ρ2 is the critical displacement difference, obtained through experiments, to minimize pressure fluctuations during braking mode switching.

[0050] Sub-condition 3: The pressure value F collected by the pressure sensor satisfies |FF d |<ρ3, and F remains constant for 0.05 seconds, where ρ3 represents the maximum permissible braking pressure deviation, obtained through testing;

[0051] Sub-condition 4: Satisfy the following formula:

[0052]

[0053] In the formula, t is the pressure value collected by the pressure sensor. The collected pressure value F satisfies |FF| d The length of time during which F remains constant when |>ρ3;

[0054] When any one of the above four sub-conditions is met, the conditions for switching between the first and second braking modes are satisfied. Attached Figure Description

[0055] To more clearly illustrate the technical solutions implemented in this application, the accompanying drawings used in the embodiments of this application are briefly introduced below. The following drawings only show a certain embodiment of this application and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1 An exploded view of the overall structure of an electromechanical linear braking device according to the present invention;

[0057] Figure 2 An assembly drawing and exploded structural view of a wedge transmission mechanism in an electromechanical linear braking device according to the present invention;

[0058] Figure 3 An exploded view of the structure of the second clutch in an electromechanical brake-by-wire device according to the present invention;

[0059] Figure 4 A perspective view of a transmission disc component in an electromechanical linear braking device according to the present invention;

[0060] Figure 5 A perspective view of the first transmission block, second transmission block, and third transmission block in an electromechanical linear braking device according to the present invention;

[0061] Figure 6 The image shows a left view and a cross-sectional view of the first transmission block, the second transmission block, and the third transmission block in an electromechanical wire control braking device according to the present invention.

[0062] Figure 7 A side view of the transmission disc in an electromechanical linear braking device according to the present invention;

[0063] Figure 8A According to the present invention, an electromechanical linear braking device is used in... Figure 7 A cross-sectional view along the AA direction;

[0064] Figure 8B According to the present invention, an electromechanical linear braking device is used in... Figure 7 A cross-sectional view along the BB direction;

[0065] Figure 8C According to the present invention, an electromechanical linear braking device is used in... Figure 7 Sectional view in the CC direction.

[0066] The parts in the diagram are marked as follows:

[0067] 1. Brake caliper body; 2. Brake friction pad; 3. Brake friction pad; 4. Brake disc; 5. First power unit; 6. Second power unit; 7. First drive shaft; 8. Second drive shaft; 9. Wedge transmission mechanism; 10. First clutch; 11. Second clutch; 12. Slewing bearing; 13. Piston; 14. Pressure sensor; 15. Rotary encoder; 16. Return spring; 17. Thrust bearing.

[0068] 101 First brake caliper body; 102 Second brake caliper body; 103 Third brake caliper body; 1011 Slide groove

[0069] 91 First transmission block; 92 Second transmission block; 93 Third transmission block; 94 Transmission disc; 95 Roller; 96 Torsion spring; 911 Triangular wedge groove; 912 Torsion spring placement groove; 921 Triangular wedge groove; 922 Torsion spring placement groove; 931 Triangular wedge groove; 941 Roller groove; 942 Slider groove

[0070] 1001 Friction disc 1002 Friction disc 1003 Electromagnet 1004 Electromagnet

[0071] 1101 Electromagnet, 1102 Slider, 1103 Compression Spring

[0072] 1301 Limiting block, 1302 Slider groove, 1303 Placement groove Detailed Implementation

[0073] This embodiment provides an electromechanical linear braking device and its control method. The invention will be further described below with reference to the accompanying drawings and embodiments.

[0074] Reference Appendix Figure 1An electromechanical wire-controlled braking device includes a brake caliper body 1, brake friction pads 2 and 3, a brake disc 3, a first power unit 5, a second power unit 6, a first drive shaft 7, a second drive shaft 8, a wedge-shaped transmission mechanism 9, a first clutch 10, a second clutch 11, a slewing bearing 12, a piston 13, a pressure sensor 14, a rotary encoder 15, a return spring 16, and a thrust bearing 17. The brake caliper body 1 includes a first brake caliper body 101, a second brake caliper body 102, and a third brake caliper body 103, which are fixed together by fastening nuts. The first power unit 5 and the second power unit 6 each consist of a motor and a planetary gear set for speed reduction and torque increase. The first power unit 5 is located outside the brake caliper body 1 and is fixed to the third brake caliper body 103 by fastening nuts, and can drive the first drive shaft 7 to rotate. The piston 6 is located inside the brake caliper body 1 and is fixed inside the piston 13 by a fastening nut. It can drive the second drive shaft 8 to rotate. There is a protruding limiting block 1301 on the outside of the piston 13. The first brake caliper body 101 has a sliding groove 1011 that matches it. The piston 13 can move longitudinally along the sliding groove 1011 but cannot rotate. One end of the return spring 16 is pressed on the outside of the piston, and the other end is placed in the mounting hole of the first brake caliper body 101. Both power units can drive the wedge transmission mechanism 9 to extend and retract longitudinally to push the piston 13, brake friction pad 3 and brake friction pad 4 to achieve braking. The wedge transmission mechanism 9 can work under three torque amplification coefficients. The pressure sensor 14 is installed between the piston 13 and the brake friction pad 2 and can measure the pressure between the piston 13 and the brake friction pad 2. The rotary encoder 15 is connected to the first drive shaft 7 and can measure the rotation angle value of the first drive shaft 7.

[0075] Reference Appendix Figure 1 Appendix Figure 2 Appendix Figure 4 Appendix Figure 5The wedge-shaped transmission mechanism 9 includes a first transmission block 91, a second transmission block 92, a third transmission block 93, a transmission disc 94, a roller 95, and a torsion spring 96. The first transmission block 91 and the second transmission block 92 are stacked on the first transmission shaft 7. The first transmission block 91 is located near the piston 13 and has a hole that mates with the first transmission shaft 7. The two are in an interference fit and can receive the torque transmitted by the first power unit 5. The second transmission block 92 has a bearing hole and is supported on the first transmission shaft 7 by the slewing bearing 12. The transmission block 93 is divided into two identical parts. These two parts are symmetrical about the axis of the wedge-shaped transmission mechanism 9 and are both fixed to the third brake caliper body 103 by fastening nuts. The transmission disc 94 has a hole that mates with the second transmission shaft 8. The two are interference fit and can receive the torque transmitted by the second power unit 6. The surfaces of the first transmission block 91, the second transmission block 92, and the third transmission block 93 away from the piston 13 are on the same plane. On this plane, the three transmission blocks are supported on the inner wall of the third brake caliper body 103 by the thrust bearing 17.

[0076] Appendix Figure 2 Appendix Figure 5 Appendix Figure 7 Appendix Figure 8A Appendix Figure 8B Appendix Figure 8C , including Figure 8A The vertical cross-section of the wedge-shaped transmission mechanism 9, cut along the center line of the first transmission block 91, is attached. Figure 8B The vertical cross-section of the wedge-shaped transmission mechanism 9, cut along the center line of the second transmission block 92, is attached. Figure 8C The vertical cross-section of the wedge-shaped transmission mechanism 9, taken along the center line of the third transmission block 93, includes two triangular wedge-shaped grooves on the surfaces of the first transmission block 91, the second transmission block 92, and the third transmission block 93 near the piston 13. The transmission disc on the surface away from the piston 13 has six frustum-shaped roller grooves 941 for placing rollers 95. The included angle between the axes of the six roller grooves 941 is 60°. The six rollers 95 are placed in these six roller grooves 941 respectively. Supported by the thrust bearing 17, the first transmission block 91, the second transmission block 92, and the third transmission block 93... The third transmission block 93 has a total of six triangular wedge grooves that press on the six rollers 95 respectively. At this time, the two inclined surfaces of each triangular wedge groove can be tangent to the rollers 95. The included angle between each pair of the first transmission block 91, the second transmission block 92, and the third transmission block 93 is also 60°. When the first transmission block 91 and the second transmission block 92 rotate around the axis of the wedge transmission mechanism 9 and the transmission disk 94 cannot rotate, or when the first transmission block 91 and the second transmission block 92 do not rotate and the transmission disk 94 rotates, the transmission disk 94 will move longitudinally under the pressure of the rollers 95.

[0077] The first transmission block 91 has the same torsion spring placement groove on the surface near the piston 13 and the second transmission block 92 has the same torsion spring placement groove on the surface away from the piston 13. The torsion spring 96 is placed in the two torsion spring placement grooves. The spring force of the torsion spring 96 can resist the angle change between the first transmission block 91 and the second transmission block 92. The torsion spring 96 has a preload force, which makes the second transmission block 92 rotate with the first transmission block 91 when it rotates, and the second transmission block 92 can always press the roller 95 into the roller groove 941.

[0078] Reference Appendix Figure 1 and attached Figure 8B The first clutch 10 includes a friction disc 1001, a friction disc 1002, an electromagnet 1003, and an electromagnet 1004. The friction disc 1001 and the electromagnet 1003 are fixed on the first transmission shaft 7 by fastening nuts. The friction disc 1002 and the electromagnet 1004 are mounted on the second transmission block 8 by fastening nuts. The cores of the two electromagnets are made of silicon steel. The two friction discs are adjacent to each other with a small gap between them. The two electromagnets are located on the outside of the two friction discs respectively. When the two electromagnets are energized, they attract each other and can push the second transmission block 92 to produce a small longitudinal displacement, thereby eliminating the gap between the two friction discs. The two friction discs are pressed together to transmit the torque generated by the first power unit 5.

[0079] Reference Appendix Figure 1 and attached Figure 3 The second clutch 11 includes an electromagnet 1101, a slider 1102, and a pressure spring 1103. The core of the electromagnet 1101 is made of silicon steel, and the slider 1102 is made of iron-nickel alloy. The piston 13 has six slider grooves 1302 that cooperate with the slider 1102 and a placement groove 1303 for placing the electromagnet 1101. The pressure spring 1103 is placed between the electromagnet 1101 and the slider 1102. The pressure spring 1103 presses the slider 1102 into the slider groove 1302, so the transmission disc 94 cannot rotate relative to the piston 13. When the electromagnet 1101 is energized, it attracts the slider 1102 to slide out of the slider groove 1302, and the transmission disc 94 can rotate relative to the piston 13.

[0080] Reference Appendix Figure 6The triangular wedge grooves on the first transmission block 91, the second transmission block 92, and the third transmission block 93 have different wedge angles. The wedge angle of triangular wedge groove 911 is α, the wedge angle of triangular wedge groove 921 is β, and the wedge angle of triangular wedge groove 931 is γ. The relationship between the three wedge angles is α > β > γ. Rotating the three transmission blocks respectively represents three driving braking modes. By designing the size of the wedge angles, the distances r1, r2, and r3 from the middle surface of the triangular wedge groove of the three transmission blocks to the center of the transmission block, the friction coefficient μ between the brake disc 4 and the two brake friction pads, and the distance R from the brake friction pad 2 to the center of the wheel, the wedge transmission mechanism 9 has three different torque amplification coefficients C1, C2, and C3, as shown in the following formula:

[0081]

[0082] In the formula, T m1 T is the torque generated by the first power unit 5. m2 The torque T is generated by the second power unit 6. b1 T b2 T b3 The braking torque applied to the brake disc 4 under three braking modes is such that the three torque amplification coefficients satisfy that C1 and C3 are both less than C2. When receiving the same amount of torque, the second braking mode using the second torque amplification coefficient C2 can obtain a larger braking torque, while the first braking mode using the first torque amplification coefficient C1 has a smaller torque amplification coefficient and higher control precision of braking force.

[0083] The three braking modes correspond to three stroke conversion coefficients S1, S2, and S3, respectively. Each stroke conversion coefficient represents the longitudinal distance the piston 13 moves per unit rotation angle of the drive shaft. S1 and S2 correspond to the longitudinal distance the piston 13 moves per unit rotation angle of the first drive shaft 7, and S3 corresponds to the longitudinal distance the piston 13 moves per unit rotation angle of the second drive shaft 8, as shown in the following formula:

[0084]

[0085] In the formula, δ1 represents the clearance coefficient between the first transmission block 91 and the roller 95 in the wedge transmission mechanism, δ2 represents the clearance coefficient between the second transmission block 92 and the roller 95 in the wedge transmission mechanism 9, and δ3 represents the clearance coefficient between the third transmission block 93 and the roller 95 in the wedge transmission mechanism 9. These three coefficients are obtained from experiments. Through the design of the parameters in the formula, the three stroke conversion coefficients satisfy S1 > S3 > S2. Compared with the second braking mode using the second stroke conversion coefficient S2, the first braking mode using the first stroke conversion coefficient S1 can make the wedge mechanism 9 extend more quickly to overcome the braking clearance and achieve braking, thus improving the response speed.

[0086] The three braking modes correspond to three maximum strokes L1, L2, and L3, respectively. The maximum stroke represents the maximum distance that the wedge-shaped transmission mechanism 9 can extend or retract, as shown in the following formula:

[0087]

[0088] In the formula, r g Let b1 be the maximum radius of roller 95, and b1, b2, and b3 be the maximum widths of the mating surfaces of the triangular wedge grooves on the three wedge transmission blocks and roller 95, respectively. Through parameter design, the three maximum strokes satisfy L3 > L1 > L2. When the vehicle is in the service braking mode with the first transmission block 91 rotating, and the wedge transmission mechanism 9 reaches its maximum stroke L1, the pressure value obtained by the pressure sensor 14 is the preset switching threshold F. s .

[0089] Furthermore, the inner wall of piston 13 is in direct contact with the surface of transmission disc 94 near piston 13, and there is a frictional fit between them with a friction coefficient of μ. p Satisfying condition μ p >tan(γ), when the second clutch 11 is disengaged, the wedge transmission mechanism 9 extends under the torque transmitted by the second power unit 6 and the transmission disc 94, and the transmission disc 94 is self-locked under the support of the third transmission block 93, so the braking force will not disappear after the second power unit 6 stops rotating.

[0090] According to a second aspect of the present invention, a wear detection method for a brake disc 4 and two brake friction pads is designed to indicate the wear condition of the two brake friction pads and the brake disc 4 and prompt the driver to perform timely maintenance and replacement. The electronic control unit records the total rotation angle values ​​θ1, θ2, θ3 collected by the rotary encoder 15 when the pressure values ​​obtained by the pressure sensor 14 are F1, F2, F3, and calculates the wear amount Δx. If the required braking force F d <F s Then F1, F2, and F3 are obtained from the following formula:

[0091]

[0092] If the required braking force F d ≥F s Then F1, F2, and F3 are obtained from the following formula:

[0093]

[0094] The wear amount is calculated using the following formula:

[0095] Δx=ε1(θ1S1-x s1 )+ε2(θ2S1-x s2 )+ε3(θ3S1-x s3 )

[0096] In the formula, ε1, ε2, and ε3 are weighting factors, satisfying ε1 + ε2 + ε3 = 1, ε1 < ε2 < ε3. If θ1ε1 is not within the set range (x s1 1.3x s1 If θ2ε2 is not within the set range (x), then ε1 = 0; if θ2ε2 is not within the set range (x), then ε1 = 0. s2 1.3x s2 If θ3ε3 is not within the set range (x), then ε2 = 0. s3 1.3x s3 If ε3 = 0, then x s1 x s1 x s1 These represent the longitudinal displacement values ​​of the piston when pressure values ​​F1, F2, and F3 are reached under unworn conditions. These values ​​were obtained experimentally. When the wear amount Δx exceeds the wear threshold Δx... l At this time, the system will send audible and visual warning signals to the driver through the in-vehicle audio system and instrument panel indicator lights.

[0097] According to a third aspect of the invention, the invention includes a control method for the electromechanical linear braking device.

[0098] The control method of the electromechanical brake-by-wire device includes a service brake control method:

[0099] Step 1) The electronic control unit receives the brake pedal opening from the driver and calculates the required braking force F. d ;

[0100] Step 2) Check whether the first power unit 5, the first drive shaft 7, the first transmission block 91, and the second transmission block 92 are faulty. If any of the above components are faulty, proceed to step 8).

[0101] Step 3) The electronic control unit starts to control the first power unit 5 to rotate. The first clutch 10 is not energized and is in the open state. The second clutch 11 is not energized and is in the engaged state. At this time, only the first transmission block 91 receives the torque rotation of the first power unit 5. Since the second clutch 11 is engaged, the piston 13 is restricted to rotate by the limit block 1301, and the transmission disk 94 cannot rotate. When the triangular wedge groove 911 on the first transmission block 91 rotates, the thickness of the contact position with the roller 95 will increase, thereby pushing the transmission disk 94 and the piston 13 to move longitudinally and perform braking. At this time, the wedge transmission mechanism 9 works in the first braking mode, with a torque amplification coefficient of C1, a stroke conversion coefficient of S1, and a maximum stroke of L1, quickly overcoming the braking gap and applying braking force.

[0102] Step 4) The electronic control unit performs wear detection. If the wear exceeds the limit, it will issue an audible and visual warning signal to the driver through the in-vehicle audio system and instrument panel indicator lights.

[0103] Step 5) Compare the required braking force F d With switching threshold F s If F d >F s Then proceed to step 7);

[0104] Step 6) The first power unit 5 increases braking force when rotating forward, decreases braking force when rotating in reverse, and maintains braking force when stalled, so that the braking force changes proportionally with the brake pedal opening until the brake pedal opening is 0, and the service braking ends.

[0105] When the conditions for switching between the first and second braking modes are met in step 7), the first clutch 10 is energized and engaged, while the second clutch 11 is de-energized and engaged. At this time, the first transmission block 91 still rotates with the first transmission shaft 7, but the roller 95 has rolled out of the triangular wedge groove 912 on the first transmission block 91, making it impossible for the wedge transmission mechanism 9 to extend or retract further. Under the action of the torsion spring 96, the triangular wedge groove 921 on the second transmission block 92 is always in close contact with the roller 95. When the first clutch 10 is engaged, the second transmission block 92 can receive the torque of the first power unit 5 to further push the transmission disc 94 to move longitudinally, providing greater braking force. At this time, the wedge transmission mechanism 9 works in the second braking mode, with a torque multiplication coefficient of C2, a stroke conversion coefficient of S2, and a maximum stroke of L2. Return to step 6).

[0106] Step 8) The electronic control unit controls the second power unit 6 to rotate, and the second clutch 11 is energized and in the disengaged state. Since the second clutch 11 is energized and disengaged, the transmission disc 94 can receive the torque of the second unit 6 and rotate inside the piston 13. The third transmission block 93 is fixed on the third brake caliper 103 and cannot move. Therefore, under the support of the triangular wedge groove 931 on the third transmission block 93, when the transmission disc 94 rotates, the transmission disc 94 and the piston 13 will also move longitudinally to achieve braking. At this time, the wedge transmission mechanism 9 works in the third braking mode, with a torque amplification coefficient of C3, a stroke conversion coefficient of S3, and a maximum stroke of L3.

[0107] Step 9) The second power unit 6 increases braking force when rotating forward, decreases braking force when rotating in reverse, and maintains braking force when stalled, so that the braking force changes proportionally with the brake pedal opening until the brake pedal opening is 0, and the service braking ends.

[0108] The control method for the electromechanical brake-by-wire device includes a parking brake control method:

[0109] Step 1) The driver presses the parking brake button, the electronic control unit controls the second power unit 6 to rotate forward, the second clutch 11 is energized and in the disengaged state, at this time the wedge transmission mechanism 9 works in the third braking mode, the piston 13 pushes the brake friction pad 2 and brake friction pad 3 to clamp the brake disc 4, so that the wheels will not turn when the vehicle is stationary at any slope, proceed to step 4).

[0110] Step 2) The first power unit 5 maintains a positive torque T d T d The second clutch 11 is energized and in the disengaged state, calculated by the electronic control unit based on the brake pedal opening. The electronic control unit then controls the second power unit 6 to provide positive torque T. p The direction of rotation of the first power unit 5 is opposite to the direction of rotation of the second power unit 6, satisfying |T p |>|T d |;

[0111] Step 3) Determine whether the first transmission block 91 has returned to its initial position based on the angle value of the first transmission shaft 7 collected by the rotary encoder 15. That is, the angle between each pair of the three transmission blocks is 60°. If it returns to the initial position, the first clutch 10 is de-energized and is in the disengaged state. The first power unit 5 stops rotating, and the second power unit 6 continues to drive the transmission disc 94 to rotate. At this time, the wedge transmission mechanism 9 works in the third braking mode. The piston 13 pushes the brake friction pad 2 and brake friction pad 3 to clamp the brake disc 4, so that the wheels will not rotate at any slope when the vehicle is stationary.

[0112] Step 4) The second power unit 6 stops rotating, the second clutch 11 is de-energized, and the piston 13 and the transmission disc 94 self-lock to maintain braking force;

[0113] Step 5) The driver presses the parking brake button again, and the electronic control unit controls the second power unit 6 to reverse. After the transmission disc 94 returns to the initial position before parking brake, the second clutch 11 engages under the action of the compression spring 1103, and the parking brake is released.

[0114] The conditions for switching between the first and second braking modes include four sub-conditions:

[0115] Sub-condition 1: The pressure value F collected by pressure sensor 14 satisfies |F s -(F+kΔx)|<ρ1, kΔx represents the compensation pressure value added due to the wear of the two brake friction pads and brake disc 4, k is the wear compensation coefficient, which is obtained through experiments, and ρ1 is the critical pressure difference, which is obtained through experiments, so as to minimize the pressure fluctuation when switching braking modes;

[0116] Sub-condition 2: The angle value θ collected by the rotary encoder 15 satisfies |L1-θS1|<ρ2, where ρ2 is the critical displacement difference, obtained through experiments, to minimize pressure fluctuations during braking mode switching.

[0117] Sub-condition 3: The pressure value F collected by pressure sensor 14 satisfies |FF d |<ρ3, and F remains constant for 0.05 seconds, where ρ3 represents the maximum permissible braking pressure deviation, obtained through testing;

[0118] Sub-condition 4: Satisfy the following formula:

[0119]

[0120] In the formula, t is the pressure value collected by pressure sensor 14. The collected pressure value F satisfies |FF| d The length of time during which F remains constant when |>ρ3;

[0121] When any one of the above four sub-conditions is met, the conditions for switching between the first and second braking modes are satisfied.

[0122] The above description is merely an embodiment of this application and does not limit the scope of protection of this application. Various modifications, equivalent substitutions, or improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. An electromechanical linear control braking device, characterized in that, The components include a brake caliper (1), brake friction pads (2), brake friction pads (3), brake disc (4), first power unit (5), second power unit (6), first drive shaft (7), second drive shaft (8), wedge transmission mechanism (9), first clutch (10), second clutch (11), slewing bearing (12), piston (13), pressure sensor (14), rotary encoder (15), reset spring (16), and thrust bearing (17). The piston (13) has a limit block (1301) on its outer surface. The brake caliper (1) includes a first brake caliper (101), a second brake caliper (102), and a third brake caliper (103). The inner wall of the first brake caliper (101) has a longitudinal groove (1011) that mates with it. The piston (13) can move longitudinally along the groove (1011) but cannot rotate. The first power unit (5) and the second power unit (6) each consist of a motor and a planetary gear set for speed reduction and torque increase. The first power unit (5) is fixed to the third brake caliper (103) by a fastening nut and can drive the first transmission shaft (7) to rotate. The second power unit (6) is fixed to the piston (13) by a fastening nut and can drive the second transmission shaft (8) to rotate. Both power units can drive the wedge transmission mechanism (9) to perform axial extension and retraction. The wedge transmission mechanism (9) can work under three torque coefficients. The pressure sensor (14) will collect the pressure value between the brake friction pad (2) and the brake disc (4). The rotary encoder (15) will collect the rotation angle value of the first transmission shaft (7). The values ​​collected by the two sensors will be processed by the control unit and used as control signals. According to the control method of the electromechanical wire brake device, the signal will be used to detect the wear of the brake friction pad (2), brake friction pad (3), and brake disc (4) and switch the braking mode. The control method of the electromechanical wire brake device includes the service brake control method and the parking brake control method. The wedge-shaped transmission mechanism (9) includes a first transmission block (91), a second transmission block (92), a third transmission block (93), a transmission disc (94), a roller (95), and a torsion spring (96). The triangular wedge grooves on the first transmission block (91), the second transmission block (92), and the third transmission block (93) have different wedge angles. The wedge angle of the triangular wedge groove (911) of the first transmission block (91) is... The wedge angle of the triangular wedge groove (921) of the second transmission block (92) is... The wedge angle of the triangular wedge groove (931) of the third transmission block (93) is The relationship between the three wedge angles is as follows: Rotating the three transmission blocks respectively represents three driving braking modes. By designing the size of the wedge angle, the distance from the middle surface of the triangular wedge groove of the three transmission blocks to the center of the transmission block is determined by the distance between the mid-surface of the mating part of the roller (95) and the triangular wedge groove of the three transmission blocks. , , The coefficient of friction between the brake disc (4) and the brake friction pads (2) and (3) The coefficient of friction between the piston (13) and the transmission disc (94) The distance R from the middle surface of the brake friction pads (2) and (3) to the center of the wheel makes the wedge transmission mechanism (9) have three different torque amplification coefficients in these three driving braking modes. , , As shown in the following formula: In the formula, The torque generated by the first power unit (5), The torque generated by the second power unit (6), , , The braking torque applied to the brake disc (4) under the three driving braking modes satisfies the following three torque amplification coefficients: and All less than ; The three driving braking modes correspond to three different travel conversion coefficients. , , The stroke conversion factor represents the distance the piston (13) moves longitudinally per unit transmission shaft rotation angle. , Corresponding to the distance the piston (13) moves longitudinally under the rotation angle of the first transmission shaft (7), The distance the piston (13) moves longitudinally corresponding to the rotation angle of the second transmission shaft (8) is as follows: In the formula, The clearance coefficient between the first transmission block (91) and the roller (95) in the wedge-shaped transmission mechanism (9) is represented. The clearance coefficient between the second transmission block (92) and the roller (95) in the wedge-shaped transmission mechanism (9) is represented. The clearance coefficients between the third transmission block (93) and the roller (95) in the wedge-shaped transmission mechanism (9) are represented by these three coefficients, which are obtained experimentally. Through the design of the parameters in the formula, the three stroke conversion coefficients satisfy the following conditions. ; The three braking modes correspond to three maximum travel distances. , , The maximum stroke represents the maximum distance that the wedge-shaped transmission mechanism (9) can extend or retract, as shown in the following formula: In the formula, The maximum radius of the roller (95) is , , These represent the maximum widths of the triangular wedge grooves and roller mating surfaces on the three wedge drive blocks. Through parameter design in the formula, the three maximum strokes satisfy... When the vehicle is in the service braking mode with the first transmission block (91) rotating, the wedge transmission mechanism (9) reaches its maximum stroke. At that time, the pressure value obtained by the pressure sensor (14) is the preset switching threshold. .

2. The electromechanical linear braking device according to claim 1, characterized in that, The wedge-shaped transmission mechanism (9) includes a first transmission block (91), a second transmission block (92), a third transmission block (93), a transmission disc (94), a roller (95), and a torsion spring (96). The first transmission block (91) and the second transmission block (92) are both provided with holes through which the first transmission shaft (7) can pass. The second transmission block (92) is supported on the first transmission shaft (7) by a slewing bearing (12). The first transmission block (91) and the first transmission shaft (7) are in an interference fit. The first transmission block (91) has a triangular wedge-shaped groove (911) on each side and a torsion spring placement groove (912) in the middle. The second transmission block (92) also has two triangular wedge-shaped grooves (921). The transmission disc (94) has a torsion spring placement slot (922) in the middle, and the torsion spring (96) is placed in the two torsion spring placement slots. The third transmission block (93) is installed inside the third brake caliper body (103) by a fastening nut. The third transmission block (93) also has two triangular wedge-shaped slots (931). The transmission disc (94) has 6 roller slots (941), 6 slider slots (942), and 1 hole that mates with the second transmission shaft. The hole and the second transmission shaft are interference fit, which can transmit the torque of the second power unit (6). The included angle between the axes of adjacent roller slots (941) is 60°. Six frustum-shaped rollers (95) are respectively installed in these 6 slots. The 6 rollers (95) are exactly the same in size and shape. Six rollers (95) are tangent to six triangular wedge grooves on three transmission blocks respectively. The second transmission block (92) can be connected to the first transmission shaft (7) through the first clutch (10). When the first transmission block (91) and the second transmission block (92) rotate around the axis of the wedge transmission mechanism (9) and the transmission disk (94) cannot rotate, or when the first transmission block (91) and the second transmission block (92) do not rotate and the transmission disk (94) rotates around the axis of the wedge transmission mechanism (9), the transmission disk (94) and the piston (13) will move longitudinally. When both sides of the triangular wedge groove on each transmission block are tangent to the roller (95), the wedge transmission structure (9) is in its initial position. At this time, the first transmission... The included angle between each pair of the first transmission block (91), the second transmission block (92), and the third transmission block (93) is 60°. The torsion spring (96) has a preload, which ensures that when the first transmission block (91) rotates, the second transmission block (92) also rotates with it, and the second transmission block (92) can always press the roller (95) into the roller groove (941). The surfaces of the first transmission block (91), the second transmission block (92), and the third transmission block (93) away from the piston (13) are all supported on the inner wall of the third brake caliper body (103) by the thrust bearing (17). The surface of the transmission disc (94) near the piston (13) is in direct contact with the inner wall of the piston (13), and the coefficient of friction between them is 1. .

3. The electromechanical linear braking device according to claim 1, characterized in that, The first clutch (10) includes a friction disc (1001), a friction disc (1002), an electromagnet (1003), and an electromagnet (1004). The friction disc (1001) and the electromagnet (1003) are mounted on the second transmission block (91) by fastening nuts. The friction disc (1002) and the electromagnet (1004) are mounted on the first transmission shaft (7) by fastening nuts. There is a gap between the two friction discs. When the electromagnets (1003) and (1004) are energized, they generate an attractive force, which drives the second transmission block (92) to produce a small longitudinal displacement, thereby eliminating the gap between the two friction discs. The two friction discs are pressed together to transmit the torque generated by the first power unit (5). The dual clutch (11) includes an electromagnet (1101), six sliders (1102), and a pressure spring (1103). The piston (13) has six slider slots (1302) that cooperate with the sliders (1102) and a placement slot (1303) for placing the electromagnet. The pressure spring (1103) is placed between the electromagnet (1101) and the sliders (1102). The pressure spring (1103) presses the sliders (1102) into the slider slots (1302), so that the transmission disc (94) cannot rotate relative to the piston (13). When the electromagnet (1101) is energized, it attracts the sliders (1102) to slide out of the slider slots (1302), and the transmission disc (94) can rotate relative to the piston (13).

4. An electromechanical linear braking device according to claim 2, characterized in that... The wedge-shaped transmission mechanism (9) can be self-locking, and the inner wall of the piston (13) forms a friction fit with the transmission disc (94), with parameters satisfying the following conditions: When the second clutch (11) is disengaged, the wedge transmission mechanism (9) extends under the torque transmitted by the second power unit (6) and the transmission disc (94). The transmission disc (94) is self-locked under the support of the third transmission block (93). The braking force will not disappear after the second power unit (6) stops rotating.

5. A control method for an electromechanical linear braking device according to claim 1, characterized in that: Including vehicle braking control methods: Step 1) The electronic control unit receives the brake pedal opening from the driver and calculates the required braking force. ; Step 2) Check whether the first power unit (5), the first drive shaft (7), the first transmission block (91), and the second transmission block (92) are faulty. If any of the above components are faulty, proceed to step 8). Step 3) The electronic control unit starts controlling the first power unit (5) to rotate. The first clutch (10) is not energized and is in the disengaged state. The second clutch (11) is not energized and is in the engaged state. At this time, the wedge transmission mechanism (9) works in the first braking mode, and the torque amplification coefficient is... The travel conversion factor is The maximum travel distance is Eliminate the braking gap and apply braking force; Step 4) The electronic control unit performs wear detection. If the wear exceeds the limit, it will issue an audible and visual warning signal to the driver through the in-vehicle audio system and instrument panel indicator lights. Step 5) Compare the required braking force With switching threshold ,like Then proceed to step 7). Step 6) The first power unit (5) increases braking force when rotating forward, decreases braking force when rotating in reverse, and maintains braking force when stalling, so that the braking force changes proportionally with the opening of the brake pedal until the opening of the brake pedal is 0, and the service braking ends. Step 7) When the switching conditions for the first and second braking modes are met, the first clutch (10) is energized and engaged, while the second clutch (11) is de-energized and engaged. At this time, the wedge transmission structure (9) operates in the second braking mode, and the torque multiplication coefficient is... The travel conversion factor is The maximum travel distance is (Return to step 6) Step 8) The electronic control unit controls the second power unit (6) to rotate, and the second clutch (11) is energized and in the disengaged state. At this time, the wedge transmission mechanism (9) works in the third braking mode, and the torque amplification coefficient is... The travel conversion factor is The maximum travel distance is ; Step 9) The second power unit (6) increases braking force when rotating forward, decreases braking force when rotating in reverse, and maintains braking force when stalling, so that the braking force changes proportionally with the opening of the brake pedal until the opening of the brake pedal is 0, and the service braking ends. Including parking brake control methods: Step 1) The driver presses the parking brake button. If the driver presses the brake pedal at this time and maintains the service brake, then proceed to Step 2). The electronic control unit controls the second power unit (6) to rotate forward, and the second clutch (11) is energized and in the disengaged state. At this time, the wedge transmission mechanism (9) works in the third braking mode. The piston (13) pushes the brake friction pad (2) and brake friction pad (3) to clamp the brake disc (4), so that the wheels will not rotate at any slope when the vehicle is stationary, and proceed to Step 4). Step 2) The first power unit (5) maintains positive torque , The second clutch (11) is energized and in the disengaged state, as calculated by the electronic control unit based on the brake pedal opening. The electronic control unit then controls the second power unit (6) to provide positive torque. The direction of rotation of the first power unit (5) is opposite to the direction of rotation of the second power unit (6), satisfying the condition that... ; Step 3) Based on the angle value of the first transmission shaft (7) collected by the rotary encoder (15), determine whether the first transmission block (91) has returned to the initial position, that is, the angle between the three transmission blocks is 60°. If it returns to the initial position, the first clutch (10) is de-energized and is in the open state. The first power unit (5) stops rotating, and the second power unit (6) continues to drive the transmission disc (94) to rotate. At this time, the wedge transmission mechanism (9) works in the third braking mode. The piston (13) pushes the brake friction pad (2) and brake friction pad (3) to clamp the brake disc (4), so that the wheels will not rotate at any slope when the vehicle is stationary. Step 4) The second power unit (6) stops rotating, the second clutch (11) is de-energized, and the piston (13) and transmission disc (94) self-lock to maintain braking force; Step 5) The driver presses the parking brake button again, and the electronic control unit controls the second power unit (6) to reverse. After the transmission disc (94) returns to the initial position before parking brake, the second clutch (11) engages under the action of the compression spring (1103), and the parking brake ends.

6. The control method for an electromechanical linear braking device according to claim 5, characterized in that, This includes wear detection and warning methods to indicate the wear condition of the brake friction pads (2), brake friction pads (3), and brake discs (4) and to prompt the driver to perform timely maintenance and replacement. The electronic control unit records the pressure value obtained by the rotary encoder (15) from the pressure sensor (14). , , Total rotation angle value collected in time , , And calculate the amount of wear. If the required braking force ,but , , Obtained from the following formula: If the required braking force ,but , , Obtained from the following formula: The wear amount is calculated using the following formula. : In the formula, , , As a weighting factor, satisfying , ,like Not within the set range If it is inside, then take ,like Not within the set range If it is inside, then take ,like Not within the set range If it is inside, then take , , , The pressure values ​​reached by the brake friction pad (2), brake friction pad (3), and brake disc (4) under unworn conditions are respectively. , , The longitudinal displacement value of piston (13) was obtained through experiments, when the wear amount Exceeding the wear threshold At this time, the system will send audible and visual warning signals to the driver through the in-vehicle audio system and instrument panel indicator lights.

7. A control method for an electromechanical linear braking device according to claim 5, characterized in that, The conditions for switching between the first and second braking modes include four sub-conditions: Sub-condition 1: Pressure value collected by pressure sensor (14) satisfy , This indicates the additional compensating pressure value due to the wear of the brake friction pads (2), (3), and (4) brake disc. The wear compensation coefficient was obtained through testing. The critical pressure difference was obtained through experiments to minimize pressure fluctuations during braking mode switching. Sub-condition 2: Angle value acquired by rotary encoder (15) satisfy , The critical displacement difference, obtained through experiments, minimizes pressure fluctuations during braking mode switching. Sub-condition 3: Pressure values ​​collected by pressure sensor (14) satisfy And F remains constant for 0.05 seconds. This indicates the maximum permissible deviation in braking pressure, obtained through testing. Sub-condition 4: Satisfy the following formula: In the formula, t is the pressure value collected by the pressure sensor (14). satisfy hour, The length of time during which it remains unchanged; When any one of the above four sub-conditions is met, the conditions for switching between the first and second braking modes are satisfied.

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