High-integration EMB actuator and gap self-adaptive control method

Abstract

The application discloses a high-integration-degree EMB actuator and a gap self-adaptive control method, and belongs to the technical field of vehicle brake-by-wire technology. A driving motor is embedded into a brake caliper body accommodating groove, and an axial overhang is shortened; the actuator adopts a three-section type shell, the middle shell is a full-laminated isolation plate, and the middle shell has the functions of isolation, support, heat dissipation and strengthening; a double-concave return spring set is arranged on the inner friction plate, the outer friction plate is actively returned through an elastic element provided with a return hook, the action line of the return force is collinear with the gravity center, and synchronous separation of the inner and outer sides is ensured; based on displacement, motor position and current multi-source sensing information, three confirmations of actuator reference self-learning, wear online identification, gap self-adaptive adjustment and screw rod active zero return are realized, so that the brake gap is kept stable in the whole life cycle, and the drag torque is effectively reduced. The application realizes the unity of low drag and consistency of brake response in the whole life based on the high-integration-degree structure.

Description

Technical Field

[0001] This invention relates to the field of vehicle brake-by-wire technology, specifically to a highly integrated EMB actuator and a gap adaptive control method. Background Technology

[0002] Electromechanical braking (EMB) systems are considered a core solution for next-generation brake-by-wire due to their advantages such as fast response, simple structure, elimination of hydraulic lines and brake fluid, and ease of chassis-level integration. However, existing EMB actuators still face a series of coupled technical challenges in wheel-end placement and control performance, including:

[0003] 1. Conflict between axial dimensions and wheel end space

[0004] Existing EMB actuators mostly employ a layout where the motor, reduction mechanism, and circuit board are stacked axially in layers, with axial dimensions generally exceeding 150mm. At the passenger wheel end, peripheral components such as the steering knuckle, drive shaft, and control arm already severely encroach on the internal space of the wheel rim. Excessive actuator axial overhang not only causes interference with surrounding components but also increases unsprung mass and worsens suspension kinematics. Although some solutions attempt to embed the motor portion into the brake caliper recess, the gear set and circuit board are still arranged in upper and lower layers, separated only by a simple thin plate. Installing the circuit board requires additional copper pillars or brackets, further compressing axial space. This "local optimization, overall looseness" design approach fails to fundamentally solve the wheel-end space bottleneck.

[0005] 2. Structural challenges in controlling drag torque

[0006] The speed at which the friction pads can quickly and completely detach from the brake disc after brake release directly determines the magnitude of the drag torque. Existing solutions mostly rely on the rotation of the brake disc to fling the friction pads off, resulting in passive return and significant issues with incomplete and asynchronous return. This lag is particularly pronounced on the outer friction pads, which are further away from the brake piston. While some solutions incorporate return springs, they lack differentiated return force designs for the inner and outer friction pads. This asynchronous return leads to uneven drag torque distribution, exacerbating uneven wear over long-term use.

[0007] 3. The brake clearance deteriorates uniformly with increasing wear.

[0008] The brake clearance (the initial distance between the friction pads and the brake disc) of the EMB actuator directly affects the braking response time. As mileage increases, the friction pads gradually wear, and the initial position of the lead screw pair needs to be continuously moved forward to compensate for the wear; otherwise, the braking free travel will gradually increase. Existing solutions lack the ability to accurately perceive and actively compensate for lead screw wear and friction pad wear in real time, resulting in a significant deterioration in braking response consistency with mileage.

[0009] 4. The contradiction between circuit board protection and compact integration

[0010] PCBAs and transmission gears are usually arranged in a shared cavity or separated by only a simple partition. The volatile lubricating grease and wear debris generated during the operation of the transmission mechanism can easily contaminate the circuit board, leading to an increased short-circuit failure rate. On the other hand, independent cavity designs often result in an increase in the radial dimension of the housing, further exacerbating the compactness problem. Summary of the Invention

[0011] The purpose of this invention is to provide a gap adaptive control method to solve the problems mentioned in the background art, such as the excessively large axial dimension of existing EMB actuators, the uneven return of inner and outer friction plates leading to high drag torque, the deterioration of response consistency due to increased braking gap with wear, and the contradiction between circuit board protection and compact integration.

[0012] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0013] A highly integrated EMB actuator includes a brake caliper body, an actuator assembly, an inner friction plate assembly, and an outer friction plate assembly;

[0014] The highly integrated EMB actuator also includes:

[0015] The brake caliper body is provided with a motor receiving slot. When the drive motor is embedded in the motor receiving slot along the axial direction of the brake disc, the axial projection of the drive motor and the brake caliper body overlaps.

[0016] The actuator assembly integrates a motor position sensor and a current sensor; and the actuator assembly includes a three-section housing structure, namely a lower housing, a middle housing and an upper housing; the lower housing has a built-in multi-stage reduction gear set and a ball screw pair, and a displacement sensor is provided at the end of the ball screw shaft; the upper housing has a built-in wheel-side circuit board; and the middle housing has a sealed wire-passing hole for the lead wire to pass through;

[0017] A first return spring assembly is provided between the friction plate back plate of the internal friction plate assembly and the brake caliper body;

[0018] The friction back plate of the outer friction plate assembly is connected to the bracket of the brake caliper body through an elastic return element.

[0019] Preferably, the middle housing is a fully bonded functional integrated isolation plate, which includes a first surface and a second surface; the first surface is bonded to the lower surface of the wheel-side circuit board through a thermally conductive interface material to support the wheel-side circuit board and conduct heat; the second surface is physically isolated from the transmission chamber of the lower housing through the solid material of the middle housing.

[0020] Preferably, the first return spring assembly includes two concave helical springs, which are symmetrically arranged at both ends of the upper part of the friction plate back plate of the inner friction plate assembly. The spring sleeves of the two concave helical springs are fitted onto a centering pin fixed on the brake caliper body, and the ends of the centering pins are engaged in the opening grooves of the friction plate back plate of the inner friction plate assembly. The initial elastic force of the first return spring assembly is greater than the sliding resistance of the friction plate of the inner friction plate assembly, and the maximum elastic force of the first return spring assembly is less than the maximum retraction resistance of the brake piston.

[0021] Preferably, the elastic return element has an integrally formed fixing part, an elastic deformation part, and a return hook part; the fixing part is fixed to the side wall of the bracket slide groove by rivets; the elastic deformation part is arched and spans the gap between the side wall of the bracket slide groove and the outer friction plate support ear; the return hook part is L-shaped and engages in the slot of the outer friction plate support ear.

[0022] Preferably, the motor position sensor is a rotary transformer or a magnetic encoder; the current sensor is a Hall effect current sensor; and the displacement sensor is a non-contact eddy current displacement sensor or a linear variable differential transformer.

[0023] A gap adaptive control method, which performs gap adaptive control based on sensing signals collected by the motor position sensor, the current sensor, and the displacement sensor, wherein the gap adaptive control includes:

[0024] Reference state recording steps: Control the drive motor to push the brake piston to move under no-load at a constant low speed until the current of the drive motor rises for the first time. Record the reference no-load displacement and reference zero displacement of the brake piston during no-load movement and store them in non-volatile memory.

[0025] Wear feature extraction steps: During braking, signals from displacement sensor, current sensor and motor position sensor are collected, and the current idle displacement, displacement-current slope, return residual displacement and return time constant are extracted;

[0026] Wear assessment steps: The ratio of the current idle stroke displacement to the reference idle stroke displacement is recorded as the wear index;

[0027] The gap adjustment requirement is triggered only when the wear index is detected to be greater than or equal to the first preset threshold.

[0028] Clearance adjustment steps: During clearance adjustment, the adjustment amount is obtained, which is the current idle travel displacement minus the linearly scaled reference idle travel displacement;

[0029] The single adjustment step size ratio of the clearance adjustment is determined based on the wear index, and the adjustment amount is allocated to subsequent brake releases to gradually execute the clearance adjustment. After each clearance adjustment, the displacement sensor is used for feedback verification.

[0030] Active zeroing step: After each brake release, the drive motor is controlled to rotate in the reverse direction at low speed; when the feedback values ​​of the motor position sensor angle, current sensor and displacement sensor simultaneously meet the preset conditions, it is determined that the ball screw has correctly returned to the zero position and the gradual clearance adjustment is stopped.

[0031] Preferably, the preset conditions include:

[0032] The deviation between the feedback angle of the motor position sensor and the target zero-position angle is ≤ ±1.0°;

[0033] The current sensor feedback value is within the no-load current range and does not show a continuous upward trend;

[0034] The deviation between the displacement sensor feedback value and the reference zero value is ≤ ±0.015mm.

[0035] Preferably, determining the single adjustment step size ratio of the clearance adjustment based on the wear index includes:

[0036] If the wear index is in the first range, the single adjustment step size is 30% of the adjustment amount;

[0037] If the wear index is in the second range, the single adjustment step size is 50% of the adjustment amount;

[0038] If the wear index exceeds the third threshold, the single adjustment step size is 80% of the adjustment amount.

[0039] Preferably, the method further includes a wear trend prediction step: storing the current free travel displacement data of each braking cycle and performing linear regression trend analysis to predict the remaining number of braking cycles when the current free travel displacement reaches the severe wear alarm threshold, and sending the wear status information through the vehicle communication network.

[0040] Preferably, if a new braking request is detected during the execution of the gap adjustment step or the active zeroing step, the current program step is immediately stopped and the braking mode is switched; if the execution of a single program step times out, the current program step is forcibly terminated and a fault code is recorded.

[0041] The beneficial effects achieved by this invention are:

[0042] (1) The drive motor of the present invention is embedded in the motor receiving groove of the brake caliper along the axial direction, so that 55% to 65% of the axial length of the motor body is within the outline of the brake caliper. The axial overhang distance of the actuator relative to the brake disc is shortened from 150 to 155 mm in the traditional layered stacking scheme to 105 to 115 mm, a reduction of about 25% to 30%. The middle shell (fully fitted functional integrated isolation plate) also serves as the PCBA mounting base, eliminating the need for copper pillars or brackets (axial height 5 to 8 mm) required for PCBA mounting in the traditional scheme, further compressing the axial space. The three-section compact shell minimizes the boundary design of each functional cavity and eliminates redundant cavities. Therefore, the actuator of the present invention can be adapted to mainstream 18-inch and above wheel rims, completely solving the space bottleneck of EMB arrangement at the wheel end of passenger cars.

[0043] (2) In this invention, the housing (fully bonded functional integrated isolation board) achieves four functions simultaneously with a single structural component: physical isolation between the transmission cavity and the circuit cavity, achieving an IP67 protection level; serving as the mounting base for the PCBA, eliminating the need for additional brackets or copper pillars; through full bonding contact with the PCBA via a thermally conductive interface material, the heat generated by the PCBA during operation is conducted to the housing for dissipation, reducing the junction temperature of key chips by approximately 15-18°C; serving as a structural reinforcement for the upper and lower housings, enhancing overall rigidity; this "one board, four uses" structural reuse design improves the space utilization rate (functional-to-volume ratio) of the actuator assembly by approximately 40% compared to the traditional "layered bracket" scheme, achieving a functional density of 6.3 functions / cm³ per unit volume, which is 65.8% higher than the traditional split-type scheme.

[0044] (3) This invention achieves synchronous disengagement of the inner and outer friction plates from the brake disc by designing differentiated return forces on the inner and outer sides; the inner friction plate provides an initial return force of ≥50N through double concave helical springs, and the spring parameters satisfy the constraint relationship that the initial elastic force is greater than the sliding resistance of the inner friction plate and the maximum elastic force is less than the maximum return resistance of the piston, ensuring that the inner plate actively disengages from the disc without hindering the normal return of the piston; the outer friction plate provides an active return pull force through an integrally stamped elastic return element, the return hook is engaged with the outer friction plate support, and the line of action of the return force is on the same horizontal line as the center of gravity of the friction plate (height difference ≤0.5mm), ensuring that no deflection torque is generated during the return process; according to bench testing, the time difference between the disengagement of the inner and outer friction plates is ≤3ms, and the dragging torque is reduced from about 3.5Nm in the traditional passive return scheme to below 2.0Nm, a reduction of more than 40%, and the dragging torque remains stable below 2.0Nm throughout the entire life cycle.

[0045] (4) Based on multi-source sensing information from displacement sensor, motor position sensor and current sensor, this invention performs reference state self-learning, online extraction of wear characteristic parameters, comprehensive wear assessment and intermittent adaptive gap adjustment; by using the ratio of the current idle stroke displacement to the reference idle stroke displacement as the wear index, the adjustment amount is calculated when the gap adjustment requirement is triggered, and the single adjustment step size ratio (30%~80%) is determined according to the size of the wear index, and the adjustment amount is distributed to be completed gradually after multiple subsequent brake releases, and the displacement sensor is used for feedback verification after each adjustment; this strategy enables the brake gap to be stably maintained within 95%~103% of the reference value throughout the entire life cycle. After 100,000 brake cycle durability tests, the brake response time fluctuation is controlled within ±4ms, which is far superior to the traditional fixed threshold scheme (±15ms).

[0046] (5) Unlike traditional solutions that rely on spring force for passive return, this invention utilizes the redundant configuration of motor position sensor and displacement sensor to execute the lead screw active zeroing program after each brake release. The motor is driven to rotate in the opposite direction at extremely low speed. The correct return is determined after meeting three conditions: the deviation between the displacement sensor feedback value and the reference zero position is ≤ ±0.015mm, the deviation between the motor position sensor feedback angle and the target zero position angle is ≤ ±1.0°, and the motor current value is within the no-load current range and has no continuous upward trend. The active zeroing program, combined with the triple confirmation logic, can control the residual displacement of the lead screw within ±0.015mm under all working conditions (-40℃~85℃, grease aging), thus eliminating the drag torque degradation caused by residual thrust from the root. At the same time, the control unit also has a wear trend prediction function. By storing the no-stroke displacement data of each braking cycle, it performs linear regression trend analysis to predict the remaining number of braking cycles that will reach the severe wear alarm threshold, and sends it to the instrument panel in the form of "remaining brake pad life" to realize intelligent maintenance prompts.

[0047] (6) The three-section detachable housing structure is combined with the detachable connection between the motor and the clamp body. Each housing joint surface is equipped with a sealing ring and is detachably connected by bolts. During maintenance, the PCBA module, gear set or motor can be replaced independently without replacing the entire actuator assembly, reducing maintenance costs by about 60%. At the same time, the sealing wire hole and double-lip rubber sealing ring on the middle housing ensure the independent sealing of the circuit cavity and the transmission cavity, avoiding the contamination of the circuit board by the volatile lubricating grease and wear debris in the transmission cavity, reducing the short circuit failure rate and improving the electronic reliability of the actuator. Attached Figure Description

[0048] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0049] Figure 1This is a schematic diagram of the structure of a highly integrated EMB actuator according to the present invention;

[0050] Figure 2 This is a schematic diagram of the steps of a gap adaptive control method according to the present invention.

[0051] In the picture:

[0052] 1. Brake caliper body; 11. Motor housing slot;

[0053] 2. Drive motor;

[0054] 3. Multi-stage reduction gear set;

[0055] 4. Ball screw assembly; 41. Ball screw shaft; 42. Screw nut;

[0056] 5. Brake piston;

[0057] 6. Internal friction pad assembly;

[0058] 7. External friction pad assembly;

[0059] 8. Lower casing;

[0060] 9. Middle shell;

[0061] 10. Upper shell;

[0062] 12. First return spring assembly;

[0063] 13. Elastic return element; 131. Return hook;

[0064] 14a. Displacement sensor; 14b. Motor position sensor. Detailed Implementation

[0065] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0066] Please see Figure 1 In this first embodiment: a highly integrated EMB actuator is provided, comprising:

[0067] The brake caliper body 1 is an integral cast aluminum part, which can be integrally cast from A356 aluminum alloy. A motor receiving groove 11 is opened on the back facing the rim, with a groove depth of 42mm and an inner diameter of 98mm. The drive motor 2 is embedded in the motor receiving groove 11 along the brake disc axis. It can be an external rotor brushless DC motor with an axial length of 65mm and an outer diameter of 92mm. At least part of the drive motor 2 body (64.6% of the axial length, which is 42mm or 65mm) is located within the axial contour range of the brake caliper body 1, so that the axial projection of the drive motor 2 and the brake caliper body 1 overlaps. The rear end cover of the drive motor 2 does not exceed the outer wall surface of the brake caliper body 1 (it can be 2mm lower than the outer wall surface of the brake caliper body 1). The stator of the drive motor 2 is detachably connected to the brake caliper body 1 by locating pins and bolts. Three locating pins and four M6 bolts can be used.

[0068] The total axial length of the actuator assembly is 108mm (from the outer wall of the brake caliper 1 to the end of the actuator), which is 44mm shorter than the traditional layered stacking scheme (152mm) using the same motor specifications, a reduction of 28.9%. The actuator's center of gravity is shifted 31mm towards the brake disc, which can effectively reduce the polar moment of inertia of the unsprung mass and improve the suspension's kinematic response. Specifically, the actuator assembly adopts a three-section housing structure, including an upper housing 10, a middle housing 9, and a lower housing 8 connected in sequence. Each housing joint surface is equipped with a sealing ring and can be detachably connected by bolts.

[0069] The lower housing 8 contains a multi-stage reduction gear set 3 and a ball screw pair 4; the gear set adopts a two-stage reduction structure with a two-stage double gear combination and a total reduction ratio of 35; the screw nut 42 is fixedly connected to the brake piston 5 by threads, and the brake piston 5 is provided with a guide seal ring on its outer circumference; the thrust of the brake piston 5 is transmitted to the friction plate back plate of the inner friction plate assembly 6 through the thrust bearing.

[0070] The middle shell 9 is a fully integrated functional isolation panel, integrally cast from aluminum alloy (or die-cast from ADC12 aluminum alloy, with external dimensions of 118mm × 86mm × 18mm). It simultaneously performs four functions: partitioning, support, heat dissipation, and reinforcement, and is the core structural component for enhancing the integration of this embodiment. The middle shell 9 has:

[0071] The first surface (facing the upper housing 10 / circuit cavity): is a precision-machined plane with a flatness ≤0.03mm (the precision-machined flatness can be 0.018mm). It forms a full-fit surface contact with the lower surface of the PCBA through a thermally conductive interface material. The thermally conductive interface material can be a thermally conductive silicone pad with a thickness of 0.5mm and a thermal conductivity of 3.5W / (m·K). This surface contact also achieves the following: serving as the mounting base for the PCBA without the need for additional brackets or copper pillars; conducting the heat generated by the PCBA during operation to the middle housing 9 for dissipation; the PCBA thickness is 1.6mm, and it is directly fixed to the threaded holes on the first surface of the middle housing 9 with four M3 bolts, without any brackets or copper pillars, which can save approximately 6mm of axial space.

[0072] The second surface (facing the lower housing 8 / transmission cavity): has a relief recess adapted to the contour of the gear set, with a solid wall thickness ≥3mm to ensure complete physical isolation between the transmission cavity and the circuit cavity; a gap of 2-3mm is maintained between the relief recess and the tip circle of the gear set; specifically, the depth of the relief recess can be 6mm, maintaining a gap of 2.3mm with the tip circle of the gear set, and the thinnest solid wall thickness of the recess can be 3.2mm. According to finite element analysis, the maximum deformation is 0.006mm under pressure fluctuation (±5kPa) inside the transmission cavity, which meets the sealing requirements;

[0073] Wiring holes and seals: Wiring holes for the power supply lead wires and sensor signal wires are provided on the middle housing 9. Rubber sealing rings are installed at the wiring holes, and the wire harness and the sealing rings are interference fit; specifically, there are three wiring holes (1 three-phase wire hole for motor and 2 wire harness holes for sensor), with a diameter of 6mm and equipped with double-lip rubber sealing rings.

[0074] The upper housing 10 and the middle housing 9 form a closed circuit cavity (cavity size 118mm×86mm×12mm, housing PCBA and connectors). The PCBA is fixed to the first surface of the middle housing 9 by bolts. The PCBA integrates a control unit (MCU), a motor drive circuit, a sensor signal conditioning circuit, and a CAN communication interface circuit.

[0075] A closed transmission cavity is formed between the lower housing 8 and the middle housing 9 (cavity dimensions 118mm×86mm×32mm, housing a gear set and lead screw pair), and the transmission cavity is filled with grease; a breather valve is provided at the bottom of the lower housing 8 to balance the air pressure inside and outside the transmission cavity;

[0076] Each housing mating surface is equipped with an O-ring (2.65mm wire diameter), and the leakage rate is ≤ after airtightness testing. .

[0077] It should be noted that in this embodiment, the middle shell 9 effectively conducts the heat of the PCBA to the entire shell surface for dissipation through full-fit thermal conduction, avoiding the accumulation of heat in the circuit cavity; according to the Arrhenius model of electrolytic capacitor life, a temperature reduction of 16°C can extend the life of electrolytic capacitors on the PCBA by about 2.5 times, significantly improving the electronic reliability of the actuator.

[0078] A first return spring assembly 12 is provided between the friction back plate of the inner friction plate assembly 6 and the brake caliper body 1; the first return spring assembly 12 includes two concave helical springs, which are symmetrically arranged at both ends of the upper part of the friction back plate of the inner friction plate assembly 6; the springs are sleeved on the centering pins fixed on the brake caliper body 1, and the ends of the pins are inserted into the U-shaped opening grooves of the friction back plate of the inner friction plate assembly 6; one end of the spring abuts against the wall of the brake caliper body 1, and the other end abuts against the friction back plate of the inner friction plate assembly 6;

[0079] It should be noted that the spring parameters satisfy the following constraints:

[0080] In the initial installation state (new friction pads), the single spring force is ≥25N and the combined force of the two springs is ≥50N, which is greater than the friction pad sliding resistance of the inner friction pad assembly 6 (approximately 30-35N), ensuring sufficient initial return force.

[0081] Under maximum compression (with full wear of the friction pads), the combined force of the two springs is less than or equal to the maximum return resistance of the brake piston 5 (approximately 150N), ensuring that the spring force does not hinder the normal return of the brake piston 5 under any operating condition.

[0082] For example, spring parameters can be Materials: wire diameter 1.2mm, pitch diameter 13mm, effective number of turns 8.5, free length 30mm, installation length 21mm.

[0083] The external friction pad assembly 7 is connected to the bracket of the brake caliper body 1 via the elastic return element 13; the elastic return element 13 is an integrally stamped spring plate structure made of SK5 spring steel strip, and has the following characteristics:

[0084] Fixing part: It is fixedly connected to the side wall of the bracket slide groove by two M4 rivets or bolts;

[0085] Elastic deformation section: It is arched and spans the gap between the side wall of the bracket slide groove and the friction plate support, with an arch height of 3-6mm (e.g., it can be set to an arch height of 5mm and a span of 20mm).

[0086] Return hook 131: L-shaped bend The snap-fit ​​end engages with the through slot of the outer friction plate support lug (snap-fit ​​end length 5mm), forming an axial limiting connection.

[0087] It should be noted that during braking, the outer friction pad moves outward along the brake disc axially, causing the return hook 131 to stretch the elastic deformation part and generate elastic deformation to store energy; after braking, the elastic deformation part releases elastic potential energy, and applies a return pulling force pointing towards the brake disc to the outer friction pad through the return hook 131, actively pulling the outer friction pad back to its initial position; the line of action of the return force of the return hook 131 acting on the friction pad is on the same horizontal line as the center of gravity of the friction pad (height difference ≤ 0.5mm), ensuring that no deflection torque is generated during the return process;

[0088] The return force of the outer friction pad elastic return element 13 is independent of the inner friction pad spring group design, realizing the differentiated return force configuration of the inner and outer sides, and ensuring that the inner and outer friction pads are simultaneously disengaged from the brake disc surface.

[0089] Displacement sensor 14a is installed at the end of the ball screw to measure the clamping force;

[0090] Motor position sensor 14b is installed at the tail of drive motor 2. It is a rotary transformer or magnetic encoder with a resolution of not less than 12 bits. It is used to collect the absolute angular position of the motor rotor and indirectly calculate the screw displacement through the reduction ratio and screw lead. It forms redundancy with displacement sensor 14a.

[0091] The current sensor, connected in series in the motor drive circuit, is a Hall effect current sensor used to collect the motor phase current in real time. The current value indirectly reflects the braking clamping force and the screw load status.

[0092] Please see Figure 2 In this second embodiment: a gap adaptive control method is provided. This embodiment is based on the highly integrated EMB actuator of the first embodiment. The method utilizes the control unit and sensor integrated on the PCBA in the middle housing 9. The control unit is configured to perform the following steps:

[0093] Step 1: Record baseline status, including:

[0094] After the actuator is installed on the vehicle for the first time or the friction pads are replaced, the control unit executes the baseline state recording procedure;

[0095] The control unit commands the drive motor 2 to rotate forward at a constant low speed (100-300 rpm), pushing the brake piston 5 forward under no-load until the current of the drive motor 2 shows its first step increase (criteria: current increment ≥ 0.1A and a continuous upward trend). For example, when the motor current increases from 0.38A (no-load) to 0.52A (increment 0.14A > 0.1A threshold), it is determined that the brake piston 5 has contacted the brake disc. The screw displacement sequence during this process is recorded, the drive is immediately stopped, and the following reference parameters are calculated and stored in non-volatile memory:

[0096] Reference travel displacement The incremental displacement of the leadscrew from the initial position to the contact position: the initial displacement sensor 14a reading is 2.456 mm, and the displacement sensor 14a reading at the contact moment is 2.776 mm. ;

[0097] Reference zero displacement value The absolute reading of the 14a displacement sensor at the starting position is 2.456 mm.

[0098] The second step, wear feature extraction, includes:

[0099] During each normal braking process, the control unit synchronously acquires signals from displacement sensor 14a, current sensor, and motor position sensor 14b, and extracts the following characteristic parameters:

[0100] Current idle travel displacement The increment of the lead screw displacement during the period from the issuance of the braking command to the initial rise of the current in drive motor 2;

[0101] Displacement-current slope : The rate of change of the screw displacement with respect to the current of the drive motor 2 within the linear establishment interval of the clamping force;

[0102] Residual displacement after return The difference between the stable displacement of the lead screw after brake release and the initial displacement before braking;

[0103] Return time constant : The exponential time constant of the lead screw displacement decay curve after brake release.

[0104] Step 3, Wear Assessment, including:

[0105] The control unit compares the current characteristic parameters with the reference parameters and calculates the wear index. ;

[0106] When A ≥ the preset first threshold (1.20~1.25), the gap adjustment requirement is triggered.

[0107] Step 4, gap adjustment, including:

[0108] When a gap adjustment requirement is triggered, the control unit performs the following operations:

[0109] Calculate the adjustment amount , The preset deviation tolerance is set to ±0.02 to 0.03.

[0110] The single adjustment step size ratio is determined based on the magnitude of the wear index A: the larger the value of A, the larger the single adjustment ratio (30%~80%).

[0111] The adjustment amount is distributed to be completed gradually after the subsequent N brake releases (N=1~5), and a partial adjustment is performed after each brake release;

[0112] After each adjustment, the actual adjustment amount is verified by feedback from displacement sensor 14a. If the deviation exceeds the limit, it is compensated and corrected in the next adjustment.

[0113] After all adjustments are completed, a verification test is performed to confirm that the current idle displacement has recovered to within the range of ≤3% of the reference value deviation.

[0114] For example, a braking measurement , Trigger gap adjustment;

[0115] Calculate the adjustment amount ;

[0116] A=1.306 is between 1.25 and 1.30 (set according to the actual threshold, here we use the 1.25 to 1.32 range and take 30% of the proportion), the single step size proportion is 30%, the single step size is 0.0275mm; the adjustment amount is 0.0916mm, between 0.1 and 0.3mm, and is distributed to N=3 times to complete;

[0117] After the first brake release: the motor rotates in the opposite direction at 600 rpm, the displacement feedback retracts by 0.027 mm, the deviation is 0.0005 mm, which is effective;

[0118] After the second brake release: the brake retraction was 0.028mm, which was effective;

[0119] After the third brake release: retraction 0.0366mm (to make up the margin), actual retraction 0.036mm, total retraction 0.091mm.

[0120] Step 5: Active zeroing. Utilizing the redundant configuration of motor position sensor 14b and displacement sensor 14a, the lead screw active zeroing procedure is executed after each brake release, including:

[0121] After the brake is released, the control unit drives motor 2 to rotate in the opposite direction at a very low speed (50-150 rpm);

[0122] Real-time monitoring of three signals: displacement sensor 14a, motor position sensor 14b, and current sensor;

[0123] The lead screw is considered to have correctly returned to the zero position when all three of the following conditions are met:

[0124] The deviation between the feedback value of displacement sensor 14a and the reference zero value is ≤ ±0.015mm;

[0125] The deviation between the feedback angle of the motor position sensor 14b and the target zero-position angle is ≤ ;

[0126] The motor current value is within the no-load current range and does not show a continuous upward trend;

[0127] After all three confirmations are successful, the return to position is marked as complete; if multiple confirmations fail consecutively, a return to position fault is determined and an alarm is issued.

[0128] It should be noted that the lead screw active zeroing program and the clearance adjustment program in the fourth step are independent of each other. That is, active zeroing is performed after each brake release, while clearance adjustment is only performed when the triggering conditions are met; the two work together through the timing scheduling of the control unit.

[0129] Step 6, Wear Trend Prediction, including:

[0130] The control unit stores a cumulative total of 2000 braking cycles. The data is used for linear regression every 1000 iterations. The current trend equation is: (n represents thousands of braking cycles).

[0131] Severe alarm threshold corresponding The predicted number of remaining cycles is Second-rate.

[0132] The predicted value is sent to the instrument panel via CAN and displayed as "Brake pad remaining life XX%".

[0133] The drag torque of the actuator in this embodiment and the three comparative schemes were tested on the same test bench. The test method was as follows: the brake was decelerated to a stop at 0.3g. After the brake was released, the brake disc was rotated at a low speed of 10rpm and the drag torque was measured. The comparison results are shown in Table 1 above.

[0134] Table 1 Comparison of Braking Dragging Torque Test Data

[0135] Traditional passive return 3.2Nm 5.8Nm 28ms inner leaf spring only 2.8Nm 4.5Nm 25ms Inner and outer leaf springs + fixed threshold adjustment 2.2Nm 3.8Nm 8ms This embodiment 1.6Nm 1.9Nm 3ms

[0136] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0137] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A highly integrated EMB actuator, comprising a brake caliper body, an actuator assembly, an inner friction plate assembly, and an outer friction plate assembly, characterized in that, The highly integrated EMB actuator also includes: The brake caliper body is provided with a motor receiving slot. When the drive motor is embedded in the motor receiving slot along the axial direction of the brake disc, the axial projection of the drive motor and the brake caliper body overlaps. The actuator assembly integrates a motor position sensor and a current sensor; and the actuator assembly includes a three-section housing structure, namely a lower housing, a middle housing and an upper housing; the lower housing has a built-in multi-stage reduction gear set and a ball screw pair, and a displacement sensor is provided at the end of the ball screw shaft; the upper housing has a built-in wheel-side circuit board; and the middle housing has a sealed wire-passing hole for the lead wire to pass through; A first return spring assembly is provided between the friction plate back plate of the internal friction plate assembly and the brake caliper body; The friction back plate of the outer friction plate assembly is connected to the bracket of the brake caliper body through an elastic return element.

2. The highly integrated EMB actuator according to claim 1, characterized in that, The middle housing is a fully bonded functional integrated isolation plate, which includes a first surface and a second surface. The first surface is bonded to the lower surface of the wheel-side circuit board through a thermally conductive interface material to support the wheel-side circuit board and conduct heat. The second surface is physically isolated from the transmission chamber of the lower housing through the solid material of the middle housing.

3. The highly integrated EMB actuator according to claim 1, characterized in that, The first return spring assembly includes two concave helical springs, which are symmetrically arranged at both ends of the upper part of the friction plate back plate of the inner friction plate assembly. The spring sleeves of the two concave helical springs are fixed to the centering pins on the brake caliper body, and the ends of the centering pins are engaged in the opening grooves of the friction plate back plate of the inner friction plate assembly. The initial elastic force of the first return spring assembly is greater than the sliding resistance of the friction plate of the inner friction plate assembly, and the maximum elastic force of the first return spring assembly is less than the maximum retraction resistance of the brake piston.

4. The highly integrated EMB actuator according to claim 1, characterized in that, The elastic return element has an integrally formed fixing part, an elastic deformation part, and a return hook part; the fixing part is fixed to the side wall of the bracket slide groove by rivets; the elastic deformation part is arched and spans the gap between the side wall of the bracket slide groove and the outer friction plate support ear; the return hook part is L-shaped and engages in the slot of the outer friction plate support ear.

5. The highly integrated EMB actuator according to claim 1, characterized in that, The motor position sensor is a rotary transformer or a magnetic encoder; the current sensor is a Hall effect current sensor; and the displacement sensor is a non-contact eddy current displacement sensor or a linear variable differential transformer.

6. A gap adaptive control method, employing the highly integrated EMB actuator as described in claim 1, characterized in that, Based on the sensing signals collected by the motor position sensor, the current sensor, and the displacement sensor, gap adaptive control is performed, the gap adaptive control including: Reference state recording steps: Control the drive motor to push the brake piston to move under no-load at a constant low speed until the current of the drive motor rises for the first time. Record the reference no-load displacement and reference zero displacement of the brake piston during no-load movement and store them in non-volatile memory. Wear feature extraction steps: During braking, signals from displacement sensor, current sensor and motor position sensor are collected, and the current idle displacement, displacement-current slope, return residual displacement and return time constant are extracted; Wear assessment steps: The ratio of the current idle stroke displacement to the reference idle stroke displacement is recorded as the wear index; The gap adjustment requirement is triggered only when the wear index is detected to be greater than or equal to the first preset threshold. Clearance adjustment steps: During clearance adjustment, the adjustment amount is obtained, which is the current idle travel displacement minus the linearly scaled reference idle travel displacement; The single adjustment step size ratio of the clearance adjustment is determined based on the wear index, and the adjustment amount is allocated to subsequent brake releases to gradually execute the clearance adjustment. After each clearance adjustment, the displacement sensor is used for feedback verification. Active zeroing step: After each brake release, the drive motor is controlled to rotate in the reverse direction at low speed; when the feedback values ​​of the motor position sensor angle, current sensor and displacement sensor simultaneously meet the preset conditions, it is determined that the ball screw has correctly returned to the zero position and the gradual clearance adjustment is stopped.

7. The gap adaptive control method according to claim 6, characterized in that, The preset conditions include: The deviation between the feedback angle of the motor position sensor and the target zero-position angle is ≤ ±1.0°; The current sensor feedback value is within the no-load current range and does not show a continuous upward trend; The deviation between the displacement sensor feedback value and the reference zero value is ≤ ±0.015mm.

8. The gap adaptive control method according to claim 6, characterized in that, The step size ratio for determining the single adjustment of the clearance based on the wear index includes: If the wear index is in the first range, the single adjustment step size is 30% of the adjustment amount; If the wear index is in the second range, the single adjustment step size is 50% of the adjustment amount; If the wear index exceeds the third threshold, the single adjustment step size is 80% of the adjustment amount.

9. The gap adaptive control method according to claim 6, characterized in that, It also includes a wear trend prediction step: storing the current free travel displacement data of each braking cycle and performing linear regression trend analysis to predict the remaining number of braking cycles when the current free travel displacement reaches the severe wear alarm threshold, and sending wear status information through the vehicle communication network.

10. The gap adaptive control method according to claim 6, characterized in that, If a new braking request is detected during the execution of the gap adjustment step or the active zeroing step, the current program step is immediately stopped and the braking mode is switched; if the execution of a single program step times out, the current program step is forcibly terminated and a fault code is recorded.

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