High-reliability electric brake system integrated with brake load detection and method thereof

Abstract

The application belongs to the technical field of electric brake, and discloses a high-reliability electric brake system and method integrated with brake load detection. The brake system comprises an electric cylinder seat and four sets of electric actuating channels arranged on the electric cylinder seat. The four sets of electric actuating channels are symmetrically arranged around the central area of the electric cylinder seat. Each set of electric actuating channel independently generates axial load and is provided with an independent annular brake load force sensor. The symmetrical multi-channel arrangement can disperse the brake force on the overall structure and provide a basis for load collection, load balancing and abnormal channel identification of each channel. The four annular brake load force sensors correspond to four sets of ball screw nut pairs. The application does not use one sensor to calculate the load of all channels, so that the load detection is accurate and efficient.

Description

Technical Field

[0001] This application belongs to the field of electric braking technology, specifically relating to a highly reliable electric braking system and method with integrated brake load detection. Background Technology

[0002] Existing electric braking systems utilize an electric mechanism to drive gears, splined shafts, and ball screw-nut pairs, converting the rotational motion of the motor into axial braking force. Compared to hydraulic or pneumatic braking methods, electric actuation methods offer advantages such as high structural integration, fast control response, and ease of digital control and condition monitoring. They are suitable for braking devices requiring multi-channel synchronous operation, compact installation, and precise load control.

[0003] Existing braking force detection methods typically include motor current estimation, mechanism displacement estimation, and external or series force sensor detection. This estimation process is affected by factors such as gear meshing clearance, ball screw transmission efficiency, lubrication status, temperature changes, structural deformation, and long-term wear, making it difficult to obtain a true, stable, and traceable mechanical braking force.

[0004] Current estimation and displacement estimation methods are indirect measurements, and their errors accumulate as the transmission state changes. While external sensors can directly measure force, they increase structural length and connection interfaces, and are susceptible to eccentric loads, assembly errors, and moving cables.

[0005] Simply connecting a conventional force sensor in series with the brake drive end not only increases axial installation dimensions and connection points but also exposes the sensor to torque, radial force, off-center load, and friction. If the sensor or cable moves with the transmission component, further issues such as cable bending, twisting, and signal instability arise. For ring sensors coaxially arranged with the ball screw, if the sensor's inner bore directly contacts the rotating component, rotational friction and radial runout will create additional strain. If the sensor rotates with the screw or spline shaft, the signal line needs to use a slip ring or flexible cable, reducing long-term reliability. Therefore, the key to structural design is ensuring the sensor housing remains fixed, that the axial reaction force to be detected passes through an elastic body, and that the central transmission component can rotate freely.

[0006] In a multi-cylinder braking system, the actual braking force of each actuation channel is not necessarily the same. Manufacturing tolerances, gear backlash, lead screw friction, bearing preload, and differences in temperature and lubrication can all cause the same current or displacement command to produce different measured loads. If the system lacks real load feedback, the controller can only compensate based on an empirical model, making it difficult to promptly identify jamming, no-load, overload, partial failure, or channel asynchrony.

[0007] The main drawbacks of existing technologies: 1. Relying on motor current, torque or displacement to indirectly estimate braking force cannot eliminate model errors caused by friction, clearance, temperature, wear and lubrication conditions; 2. External or series force sensors increase axial dimensions and connection interfaces, which is not conducive to the compactness and weight reduction of the electric cylinder base; 3. The sensor is prone to being subjected to torque, radial force and off-center load at the same time, which causes the output signal to contain non-axial parasitic strain; 4. The cable of a movable sensor is prone to repeated bending, twisting or stretching, which reduces signal continuity and lifespan. 5. A single indirect feedback cannot reflect the actual load of multiple actuation channels separately, making it difficult to perform balanced control and fault location. 6. Conventional elastomers may suffer permanent deformation or fatigue damage under emergency braking impact and long-term cyclic loading; 7. The strain gauge signal is relatively weak. If the conditioning circuit is far from the sensitive element, it is easily affected by temperature drift, line noise and electromagnetic interference. 8. Lack of integrated sealing, protection, and static wiring design suitable for high-temperature, vibration, shock, and polluted environments. Summary of the Invention

[0008] The purpose of this application is to address the problems existing in the prior art and to provide a highly reliable electric braking system and method with integrated brake load detection.

[0009] To solve the technical problem, the technical solution of this application is: a high-reliability electric braking system with integrated brake load detection, including an electric cylinder base and four sets of electric actuation channels arranged on the electric cylinder base. The four sets of electric actuation channels are symmetrically arranged around the central area of ​​the electric cylinder base. Each set of electric actuation channels independently generates axial load and is equipped with an independent annular brake load force sensor. The annular brake load force sensor is externally connected to a controller. Each set of the electric actuation channel includes at least an electric mechanism, a transmission assembly, a splined shaft, a ball screw and nut pair, a cylindrical thrust roller bearing, and a brake output end. The axis of each electric mechanism is offset from the axis of the corresponding ball screw and nut pair. The torque output by the electric mechanism is transmitted to the ball screw and nut pair via the transmission assembly. One end of the lead screw shaft of the ball screw and nut pair is inserted into the splined shaft, and the other end of the lead screw shaft of the ball screw and nut pair is connected to the brake output end to generate an axial load. The splined shaft is coaxial with the ball screw and nut pair, and the end of the splined shaft is fixed to the electric cylinder base. The annular brake load force sensor is fixedly installed inside the electric cylinder base, and the annular brake load force sensor is sleeved on the outer circumference of the ball screw nut pair. The cylindrical thrust roller bearing is located between the ball screw nut pair and the axial force-bearing surface of the annular brake load force sensor.

[0010] Preferably, the transmission assembly includes a coupling gear and an intermediate coupling gear, the drive gear of the electric mechanism meshes with the coupling gear, the coupling gear meshes with the intermediate coupling gear, and the intermediate coupling gear meshes with the outer periphery of the nut of the ball screw nut pair.

[0011] Preferably, the cylindrical thrust roller bearing is disposed on the right end face of the nut of the ball screw nut pair, and the cylindrical thrust roller bearing is disposed on the left end face of the annular brake load force sensor.

[0012] Preferably, one end of the splined shaft is inserted into the center of the ball screw nut assembly, and the other end of the splined shaft is fixed to the electric cylinder seat through a mounting flange. The ball screw nut assembly moves axially to output axial load.

[0013] Preferably, the annular brake load force sensor has an annular structure, and the central through hole of the annular brake load force sensor is coaxial with the ball screw nut pair; a radial gap is provided between the central through hole of the annular brake load force sensor and the ball screw nut pair, and the size of the radial gap is greater than 0.5mm. The radial gap prevents the radial runout and surface friction of the ball screw nut pair from being directly applied to the annular brake load force sensor.

[0014] Preferably, the annular brake load force sensor includes a housing, an annular elastomer, a cable, eight strain gauges, a transmitter plate, and a high-temperature potting material. The annular elastomer is disposed inside the housing, and the eight strain gauges are arranged circumferentially along the annular elastomer to form at least one bridge strain measurement circuit. The transmitter plate is disposed inside the housing, and the eight strain gauges are electrically connected to the transmitter plate. The transmitter plate is electrically connected to the cable, and the cable is radially led out from the housing and fixed in the cable channel of the electric cylinder base and externally connected to the controller. The transmitter plate, strain gauge leads, and welding parts are fixed and sealed by the high-temperature potting material.

[0015] Preferably, the housing is provided with mounting ears on opposite sides, and the two mounting ears are fixed to the electric cylinder seat by two screws. The housing and cable of the annular brake load force sensor remain stationary during braking. The outer shell is made of 304 stainless steel, and the annular elastomer is made of 17-4PH precipitation hardening stainless steel.

[0016] Preferably, a high-reliability electric braking method integrating brake load detection, utilizing the aforementioned high-reliability electric braking system with integrated brake load detection for braking operation, specifically includes the following steps: Step 1: The controller receives the braking command and distributes the target load to the four sets of electric actuation channels; Step 2: The electric mechanism starts, and the output torque is transmitted to the ball screw nut pair through the transmission assembly and spline shaft; Step 3: The ball screw and nut assembly converts the rotational motion into axial motion, forming a braking force and a corresponding axial reaction force. The braking force acts on the braking output end, generating an axial load. Step 4: The axial reaction force is applied to the annular elastic body of the annular brake load force sensor through the cylindrical thrust roller bearing, and the strain gauge converts the strain of the annular elastic body into a bridge circuit electrical signal. Step 5: The transmitter board amplifies, filters, and compensates the signal, and outputs the measured load Fi of the corresponding electric actuation channel to the controller; Step 6: The controller adjusts the motor commands based on the load error between the target load and the measured load, and performs load balancing between channels; Step 7: If overload, no load, sudden load change, or inconsistency among multiple channels is detected, the controller will execute alarm, load limiting, compensation, or safety mode. Step 8: When the brake is released, the controller drives each electric actuation channel to move in the opposite direction and confirms whether the braking force is released as expected through the load signal.

[0017] Preferably, the controller is used to calculate the measured total load, Fsum=F1+F2+F3+F4, and compare the deviation between the measured load of any electric actuation channel and the multi-channel average load Favg. The load error Ei = Fset,i - Fi, i = 1, 2, 3, 4, where Fset,i is the target load and Fi is the measured load of the corresponding annular brake load force sensor. The controller adjusts the electric mechanism drive command according to the load error so that the measured load of each electric actuator channel approaches the target load.

[0018] Preferably, the measured load of the annular brake load force sensor is Fi=Kf·Ui, where Ui is the output of each transmitter board and Kf is the force coefficient obtained through standard load calibration.

[0019] Compared with the prior art, the advantages of this application are: (1) This application includes an electric cylinder base and four sets of electric actuation channels set on the electric cylinder base. The four sets of electric actuation channels are symmetrically arranged around the central area of ​​the electric cylinder base. Each set of electric actuation channels generates axial load independently and is equipped with an independent annular brake load force sensor. The symmetrical multi-channel arrangement can distribute the braking force in the overall structure and provide a basis for the acquisition of loads in each channel, load balancing and abnormal channel identification. The four annular brake load force sensors correspond to four sets of ball screw nut pairs respectively. Instead of using one sensor to calculate the load of all channels, the load detection is accurate and efficient. (2) This application provides a highly reliable electric braking system with integrated brake load detection. The annular brake load force sensor is set in the axial reaction force transmission path between the ball screw nut pair and the electric cylinder seat, so that the annular brake load force sensor can directly detect the real mechanical braking force. The detection quantity of this application is closer to the real load at the brake actuation end. It does not depend on the long-term stability of the torque constant, transmission efficiency and friction coefficient of the electric mechanism, which is conducive to forming a closed-loop regulation with the actual braking force as the control object. (3) This application separates the rotary transmission from the axial load transmission by setting a cylindrical thrust roller bearing on the force-bearing side of the annular brake load force sensor; and reduces the influence of radial runout, friction and off-center load on the measurement signal by setting a radial clearance between the central through hole of the annular brake load force sensor and the ball screw nut pair. (4) The ring brake load force sensor of this application is mounted on the outer periphery of the ball screw nut pair and fixedly installed on the electric cylinder seat by the mounting ear, which saves space and is conducive to the compactness and weight reduction of the electric cylinder seat; the ring brake load force sensor of this application does not rotate with the spline shaft or ball screw, but is set inside the electric cylinder seat as a fixed reaction force measuring element. At the same time, the housing and cable of the ring brake load force sensor remain stationary during the braking process, which improves the signal continuity and service life. (5) This application also improves the load-bearing capacity, measurement accuracy, anti-interference ability and environmental adaptability of the annular brake load force sensor by using a 17-4PH integrated annular elastomer, circumferential multi-strain gauge, built-in transmitter plate, fixed radial output line and potting sealing structure. (6) This application feeds back the load signal of each set of electric actuation channels to the controller for closed-loop regulation, load balancing, fault diagnosis and redundant control, so that the braking system still has the ability to monitor, judge and compensate under the condition of single channel performance change or abnormality. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a high-reliability electric braking system with integrated brake load detection according to this application; Figure 2 for Figure 1 Sectional view along axis AA; Figure 3 This is a schematic diagram showing the connection between the electric actuation channel and the annular brake load force sensor in this application; Figure 4 This is a schematic diagram of the front view structure of the annular brake load force sensor of this application; Figure 5 This is a top cross-sectional view of the annular brake load force sensor of this application; Figure 6This is a von Mises stress contour plot of the annular brake load force sensor of this application under a rated center load of 16kN; Figure 7 The image shows the von Mises stress contour plot of the annular brake load force sensor of this application under a 32kN, 3mm off-center load.

[0021] Figure label: 1. Electric cylinder base; 2. Electric actuation channel; 3. Annular brake load force sensor; 2-1. Electric mechanism; 2-2. Coupling gear; 2-3. Intermediate coupling gear; 2-4. Splined shaft; 2-5. Ball screw and nut pair; 2-6. Cylindrical thrust roller bearing; 2-7. Brake output end. 3-1. Housing; 3-2. Annular elastomer; 3-3. Cable; 3-4. Strain gauge; 3-5. Transmitter plate; 3-6. High-temperature potting material. 3-1-1. Install the ear. Detailed Implementation

[0022] The present application is described in detail below with reference to the accompanying drawings and specific embodiments, but the present application is not limited to these embodiments. The present application covers any alternatives, modifications, equivalent methods, and solutions made within the spirit and scope of the present application. To provide the public with a thorough understanding of the present application, specific details are described in detail in the following embodiments, but those skilled in the art will fully understand the present application even without these detailed descriptions.

[0023] This application, without changing the main drive shaft of the ball screw or excessively increasing the size of the electric cylinder seat, arranges a high-strength ring force sensor in the axial reaction path of the brake load, and separates the axial load detection from the rotary transmission through thrust bearings, central through-hole clearance, symmetrical installation, and fixed installation.

[0024] Based on this, this application further utilizes the load feedback of multiple independent electric actuation channels to achieve closed-loop regulation of actual braking force, consistent control of load in each channel, identification of abnormal channels, and scalable redundant braking control, thereby improving the strength, measurement accuracy, feedback accuracy, and long-term operational reliability of the braking system.

[0025] like Figures 1-5 As shown, this application discloses a high-reliability electric braking system with integrated brake load detection, including an electric cylinder base 1 and four sets of electric actuation channels 2 disposed on the electric cylinder base 1. The four sets of electric actuation channels 2 are symmetrically arranged around the central area of ​​the electric cylinder base 1. Each set of electric actuation channels 2 independently generates axial load and is equipped with an independent annular brake load force sensor 3. The annular brake load force sensor 3 is externally connected to a controller. Each set of the electric actuation channel 2 includes at least an electric mechanism 2-1, a transmission assembly, a splined shaft 2-4, a ball screw nut pair 2-5, a cylindrical thrust roller bearing 2-6, and a brake output end 2-7. The axis of each set of the electric mechanism 2-1 is offset from the axis of the corresponding ball screw nut pair 2-5. The torque output by the electric mechanism 2-1 is transmitted to the ball screw nut pair 2-5 through the transmission assembly. One end of the screw shaft of the ball screw nut pair 2-5 is inserted into the splined shaft 2-4, and the other end of the screw shaft of the ball screw nut pair 2-5 is connected to the brake output end 2-7 to generate an axial load. The splined shaft 2-4 is coaxially arranged with the ball screw nut pair 2-5, and the end of the splined shaft 2-4 is fixed to the electric cylinder base 1. The annular brake load force sensor 3 is fixedly installed inside the electric cylinder seat 1, and the annular brake load force sensor 3 is sleeved on the outer periphery of the ball screw nut pair 2-5. The cylindrical thrust roller bearing 2-6 is disposed between the ball screw nut pair 2-5 and the axial force-bearing surface of the annular brake load force sensor 3.

[0026] like Figure 2 As shown, preferably, the transmission assembly includes a coupling gear 2-2 and an intermediate coupling gear 2-3. The drive gear of the electric mechanism 2-1 meshes with the coupling gear 2-2, the coupling gear 2-2 meshes with the intermediate coupling gear 2-3, and the intermediate coupling gear 2-3 meshes with the outer circumference of the nut of the ball screw nut pair 2-5.

[0027] like Figure 2 , 3 As shown, preferably, the cylindrical thrust roller bearing 2-6 is disposed on the right end face of the nut of the ball screw nut pair 2-5, and the cylindrical thrust roller bearing 2-6 is disposed on the left end face of the annular brake load force sensor 3.

[0028] like Figure 3 As shown, preferably, one end of the spline shaft 2-4 is inserted into the center of the ball screw nut pair 2-5, and the other end of the spline shaft 2-4 is fixed to the electric cylinder seat 1 through a mounting flange. The ball screw nut pair 2-5 moves axially to output axial load.

[0029] like Figure 3 As shown, preferably, the annular brake load force sensor 3 has an annular structure, and the central through hole of the annular brake load force sensor 3 is coaxial with the ball screw nut pair 2-5; a radial gap is provided between the central through hole of the annular brake load force sensor 3 and the ball screw nut pair 2-5, and the size of the radial gap is greater than 0.5mm. The radial gap prevents the radial runout and surface friction of the ball screw nut pair 2-5 from being directly applied to the annular brake load force sensor 3.

[0030] like Figure 4 , 5As shown, preferably, the annular brake load force sensor 3 includes a housing 3-1, an annular elastomer 3-2, a cable 3-3, eight strain gauges 3-4, a transmitter plate 3-5, and a high-temperature potting material 3-6. The annular elastomer 3-2 is disposed inside the housing 3-1. The eight strain gauges 3-4 are arranged circumferentially along the annular elastomer 3-2 to form at least one bridge strain measurement circuit. The transmitter plate 3-5 is disposed inside the housing 3-1. The eight strain gauges 3-4 are electrically connected to the transmitter plate 3-5 respectively. The transmitter plate 3-5 is electrically connected to the cable 3-3. The cable 3-3 is radially led out from the housing 3-1 and fixed in the cable channel of the electric cylinder seat 1 and externally connected to the controller. The transmitter plate 3-5, the strain gauge 3-4 leads, and the welding parts are fixed and sealed by the high-temperature potting material 3-6.

[0031] like Figure 5 As shown, preferably, the housing 3-1 is provided with mounting ears 3-1-1 on opposite sides, and the two mounting ears 3-1-1 are fixed to the electric cylinder seat 1 by two screws. The housing 3-1 and cable 3-3 of the annular brake load force sensor 3 remain stationary during braking. The outer shell 3-1 is made of 304 stainless steel, and the annular elastomer 3-2 is made of 17-4PH precipitation hardening stainless steel.

[0032] Preferably, a high-reliability electric braking method integrating brake load detection, utilizing the aforementioned high-reliability electric braking system with integrated brake load detection for braking operation, specifically includes the following steps: Step 1: The controller receives the braking command and distributes the target load to the four sets of electric actuation channels 2; Step 2: The electric mechanism 2-1 starts, and the output torque is transmitted to the ball screw nut pair 2-5 through the transmission assembly and spline shaft 2-4; Step 3: The ball screw nut pair 2-5 converts the rotational motion into axial motion, forming a braking force and a corresponding axial reaction force. The braking force acts on the braking output end, generating an axial load. Step 4: The axial reaction force is applied to the annular elastic body 3-2 of the annular brake load force sensor 3 via the cylindrical thrust roller bearing 2-6. The strain gauge 3-4 converts the strain of the annular elastic body 3-2 into a bridge circuit electrical signal. Step 5: Transmitter board 3-5 amplifies, filters, and compensates the signal, and outputs the measured load Fi of the corresponding electric actuation channel 2 to the controller; Step 6: The controller adjusts the motor commands based on the load error between the target load and the measured load, and performs load balancing between channels; Step 7: If overload, no load, sudden load change, or inconsistency among multiple channels is detected, the controller will execute alarm, load limiting, compensation, or safety mode. Step 8: When the brake is released, the controller drives each electric actuation channel 2 to move in the opposite direction and confirms whether the braking force is released as expected through the load signal.

[0033] Preferably, the controller is used to calculate the measured total load, where the measured total load Fsum = F1 + F2 + F3 + F4, and compare the deviation between the measured load of any electric actuation channel 2 and the multi-channel average load Favg. The load error Ei = Fset,i - Fi, i = 1, 2, 3, 4, where Fset,i is the target load and Fi is the measured load of the corresponding annular brake load force sensor 3. The controller adjusts the drive command of the electric mechanism 2-1 according to the load error so that the measured load of each electric actuation channel 2 approaches the target load.

[0034] Preferably, the measured load Fi of the annular brake load force sensor 3 is Fi=Kf·Ui, where Ui is the output of each transmitter board 3-5, and Kf is the force coefficient obtained by standard load calibration.

[0035] Example 1 In this embodiment, four sets of independent electric actuation channels 2 are set in the electric cylinder base 1 and arranged symmetrically around the electric cylinder base (the four channels are spatially independent but are installed in the same electric cylinder base). Each set of electric actuation channels 2 can independently generate axial braking force and is equipped with an independent annular brake load force sensor 3. Each set of electric actuation channels 2 includes an electric mechanism, a coupling gear, an intermediate coupling gear, a spline shaft, a GQ14×3 ball screw nut pair, and a cylindrical thrust roller bearing. This structure provides a mechanical basis for direct channel measurement and closed-loop control.

[0036] The symmetrical multi-channel arrangement enables the braking force to be distributed and transmitted throughout the overall structure, and provides a basis for load acquisition, load balancing and abnormal channel identification for each channel. The four annular brake load force sensors 3 correspond to four sets of ball screw nut pairs respectively, and the load of all channels is not calculated by using a single sensor.

[0037] The axis of the electric mechanism is offset from the axis of the corresponding ball screw nut pair, and the torque output by the electric mechanism is transmitted to the ball screw nut pair through the coupling gear and the intermediate coupling gear.

[0038] The ring-shaped brake load force sensor 3 used has a rated load of 16kN. It contains a 17-4PH ring elastomer, eight strain gauges and a transmitter plate. It is protected by a 304 stainless steel shell, high-temperature silicon-based potting compound and polytetrafluoroethylene insulated cable. The sensor must withstand the impact load during emergency braking and maintain zero point and sensitivity stability during long-term cyclic braking. Therefore, its structural strength, fatigue life, resistance to off-center load and environmental adaptability directly affect the reliability of the entire braking system.

[0039] By placing the annular brake load force sensor 3 within the fixed reaction force transmission path of the electric cylinder base 1, the axial reaction force generated by the ball screw nut pair can be directly detected. This detected quantity is closer to the actual load at the brake actuation end and does not depend on the long-term stability of the electric mechanism's torque constant, transmission efficiency, and friction coefficient, which is beneficial for forming a closed-loop regulation with the actual braking force as the control object.

[0040] The braking system also requires that the load signals of each channel have a consistent calibration relationship and a stable zero point. Only when the controller obtains independent and reliable measured loads can it compare the forces on each channel, correct synchronization errors, and identify jamming, no-load and sensor failures based on load mutations, long-term deviations or signal anomalies.

[0041] The sensor installation area is simultaneously subject to vibration, shock, temperature rise, oil contamination, and electromagnetic interference. This application employs fixed installation, radial stationary cabling, near-end signal conditioning, and overall potting protection, which can reduce the risk of fatigue in moving cables and long-distance transmission of low-level signals, providing a structural and electrical foundation for long-term continuous feedback.

[0042] Example 2 This embodiment provides a detailed description of a single set of electrically actuated channels, as follows: In the single set of electric actuator channel 2, the rotational motion output by the electric mechanism is transmitted to the ball screw nut pair after being changed and shifted by the gear set. The ball screw nut pair is coaxially set with the spline shaft. One end of the spline shaft is fixed on the electric cylinder base 1, so that the offset electric mechanism can drive the ball screw nut pair while maintaining the overall compact structure. The ball screw nut pair converts the rotational motion into axial motion and forms a braking force.

[0043] The electric cylinder base 1 provides a common positioning reference for the electric mechanism, transmission components, ball screw nut pair, and annular brake load force sensor 3. The annular brake load force sensor 3 is not mounted on the output shaft of the electric mechanism, nor does it rotate with the splined shaft or ball screw. Instead, it is set inside the electric cylinder base 1 as a fixed reaction force measuring element.

[0044] The annular brake load force sensor 3 adopts an annular structure, with its central through hole coaxial with the ball screw nut pair. The sensor housing is fixed to the electric cylinder base 1 by two oppositely arranged mounting ears 3-1-1 and two M3 screws. The sensor housing and cable remain stationary during operation.

[0045] This structure allows the annular brake load force sensor 3 to be arranged around the ball screw nut pair and to be symmetrically fixed to the electric cylinder seat 1 via two mounting ears 3-1-1.

[0046] The cylindrical thrust roller bearing is disposed between the ball screw nut pair and the axial force-bearing surface of the annular brake load force sensor 3. The axial reaction force generated by the ball screw nut pair is first transmitted to the cylindrical thrust roller bearing, then the cylindrical thrust roller bearing acts on the annular elastic body 3-2, and finally transmitted to the electric cylinder seat 1 through the sensor housing 3-1, the mounting ear 3-1-1 and the fasteners.

[0047] In the assembly model, the sensor is in contact with the cylindrical thrust roller bearing and the electric cylinder base. The minimum geometric clearance between the sensor and the ball screw nut pair is about 0.5 mm. This clearance prevents the radial runout and surface friction of the central rotating part from being directly applied to the sensor.

[0048] The cylindrical thrust roller bearing allows the ball screw transmission components to rotate relative to the fixed sensor, so that the axial reaction force to be detected passes through the annular brake load force sensor 3, while the rotational torque is mainly borne by the bearing and transmission structure, thus forming a clear force measurement path: ball screw axial reaction force → cylindrical thrust roller bearing → annular elastomer → sensor housing and mounting lug → electric cylinder base.

[0049] Such integrated solutions impose mutually restrictive requirements on the sensor structure: the elastomer must have sufficiently high yield strength and fatigue strength to withstand rated load and transient overload, and must also generate repeatable and distinguishable elastic strain within the working load range; at the same time, it is also necessary to reduce the influence of eccentricity, bending moment, temperature gradient and installation preload on the measurement results.

[0050] The annular elastomer described in this application is made of 17-4PH precipitation-hardening stainless steel. Compared with open or slender beam elastomers, the closed annular load-bearing structure can form a continuous force path in a limited radial space, taking into account both axial deformation sensitivity and overall load-bearing capacity.

[0051] During emergency braking, impact peak values ​​may exceed the steady-state load. High yield strength materials can reduce the risk of plastic deformation in the elastomer; a ring-shaped symmetrical structure can reduce excessive local stress concentration. COMSOL three-dimensional static simulation was used to verify this, and the results are as follows: like Figure 6 , 7 As shown, to verify the static strength and elastic response of the ring brake load force sensor under rated load, overload, limit load, and off-center load conditions, a three-dimensional small deformation linear elastic model was established using the SolidMechanics interface of COMSOL Multiphysics 6.3. The model is based on... The center distance between the 6.10mm central hole and the 46mm mounting hole is established; the lower annular support surface of the sensor simulates its contact support with the electric cylinder seat, the bottom surface of the mounting ear simulates screw clamping, and the upper annular force-bearing surface applies axial braking reaction force. Figure 6This is a von Mises stress contour plot of a ring-shaped brake load sensor under a rated center load of 16 kN. Figure 7 The image shows the von Mises stress contour plot of a ring-shaped brake load sensor under a 32kN, 3mm off-center load.

[0052] The material was selected as 17-4PH type high-strength stainless steel with an elastic modulus of 200 GPa and a Poisson's ratio of 0.29, and 1000 MPa was used as the conservative yield strength reference value. The model was divided into 13,426 tetrahedral elements, with a total of 63,012 degrees of freedom. The simulation results for five types of working conditions and extreme values ​​are shown in the table below: When the load at the center increases from 16kN to 40kN, the maximum equivalent stress, maximum displacement and axial strain increase approximately proportionally with the load, indicating that the structure within the analysis range maintains linear elasticity and forms a clear and stable axial force transmission path.

[0053] The most unfavorable load condition is 32 kN with a 3 mm eccentricity. The maximum equivalent stress is 64.33 MPa, the maximum displacement is 2.02 μm, and the maximum absolute axial strain is 329.19 με. The static safety factor is approximately 15.55. Compared with a 32 kN central load, the 3 mm eccentricity increases the maximum stress by approximately 32.5%, the maximum displacement by approximately 39.5%, and the maximum axial strain by approximately 32.6%.

[0054] The above results indicate that the coaxial mounting, contact support, and limiting structure of the electric cylinder base, cylindrical thrust roller bearing, and annular brake load sensor can reduce the adverse effects of eccentric loading; the micron-level deformation balances structural stiffness and detectable elastic strain, providing a structural basis for rapid and stable brake load feedback.

[0055] It should be noted that this simulation is based on a simplified static model established by the identifiable dimensions and common assembly support relationships in the existing drawings. It does not include the actual internal elastic beams, strain gauge bridges, bolt preload, contact friction, and cyclic fatigue. Therefore, the simulation results are used to demonstrate static strength, linear elasticity, and the effects of eccentric load, and cannot be equated with measurement accuracy, calibration coefficient, or fatigue life alone.

[0056] Example 3 The annular brake load force sensor 3 uses high-temperature silicon-based potting compound to fix and seal the transmitter board, strain gauge leads and welding parts, which can reduce the impact of vibration, impact, moisture and contaminants on the internal electrical connections.

[0057] The strain gauge is bonded or protected with polyurethane material, the cable is insulated with polytetrafluoroethylene, and the housing is made of corrosion-resistant stainless steel. This combination of materials is used to improve the sensor's adaptability to temperature rise, vibration, oil contamination, and humid environments.

[0058] The 304 stainless steel housing serves the functions of installation, protection, and force transmission, isolating the sensitive elastomer from external impacts, contamination, and installation tools. This functional separation of the housing and elastomer helps improve the overall mechanical protection capability of the device without compromising the measurement performance of the sensitive element.

[0059] The system can also perform zero-point self-checks using no-load conditions or known mechanical conditions, and compensate for the zero point and sensitivity of the bridge circuit based on temperature sensing information. If the eight strain gauges form two independent bridge circuits, the outputs of the two bridge circuits can also be compared to perform sensor internal consistency diagnosis.

[0060] Eight strain gauges are arranged circumferentially along the ring-shaped elastic body, which can form at least one bridge strain measurement circuit. Circumferential multi-point strain acquisition can combine the axial strain at different positions of the elastic body, enhance the effective axial load signal, and suppress output inconsistencies caused by unilateral off-center loading, bending moment and local installation errors.

[0061] The sensor output and the measured axial load can be calibrated to have an approximately linear relationship: Fi = Kf·Ui, where Ui is the output of each transmitter board (3-5), and Kf is the force coefficient obtained through standard load calibration. In actual use, the final load value is determined by zero-point compensation, temperature compensation, and sensitivity calibration parameters.

[0062] The cylindrical thrust roller bearings 2-6 bear the rotational contact, and the central clearance avoids radial friction between the sensor and the ball screw pair, so that the sensor mainly responds to the axial reaction force. This mechanical decoupling measure reduces parasitic strain from the load source and is more stable than compensating for mixed signals only in software.

[0063] Example 4 The transmitter board 3-5 is installed inside the annular brake load force sensor 3. It is used to bridge power supply, amplify, filter, zero-point compensate and output conversion of the weak electrical signal output by the strain gauge 3-4. The weak signal is conditioned at a position close to the strain gauge, which can shorten the low-level signal transmission distance and reduce the influence of external electromagnetic interference and line impedance changes.

[0064] The cable is insulated with polytetrafluoroethylene (PTFE) and is radially led out from the sensor housing and fixed inside the cable channel. Since the sensor does not move with the rotating components, the cable does not require slip rings and is not subjected to periodic torsion, thereby improving the continuity and long-term stability of the feedback signal.

[0065] For the i-th channel, the controller calculates the load error Ei = Fset,i - Fi, i = 1, 2, 3, 4, where Fset,i is the target load for each channel, and Fi is the measured load of the corresponding annular brake load sensor 3. The controller adjusts the drive command of the electric mechanism according to the load error, so that the measured load of each electric actuation channel 2 approaches the target load.

[0066] Each of the four sets of electric actuation channels 2 is equipped with an independent force sensor. The controller can calculate the measured total load Fsum=F1+F2+F3+F4 and compare the deviation between the measured load of any electric actuation channel 2 and the multi-channel average load Favg.

[0067] When the load growth rate of a certain channel is abnormal, there is no load for a long time under a given motor command, the allowable load is exceeded, or the difference between the channel and other channels exceeds the set threshold, the controller can determine that the channel may be stuck, loosely connected, have transmission failure, or be malfunctioning.

[0068] When the system control strategy allows, abnormal channel commands can be reduced, and load compensation can be performed by the remaining normal channels; alternatively, during emergency braking, a preset safety control mode can be switched. This function elevates the force sensor from a simple measuring element to the basis for system safety monitoring and control decisions.

[0069] This application directly measures the actual axial reaction force generated by the ball screw nut pair, reducing errors caused by indirect estimations of current, torque, or displacement. A ring-shaped brake load force sensor is coaxially mounted around the ball screw nut pair, maintaining the continuity of the transmission axis and minimizing the impact of the added force measurement structure on the overall dimensions. Cylindrical thrust roller bearings and radial clearance isolate torque, rotational friction, and radial runout, improving the accuracy of axial force measurement. The 17-4PH ring elastomer possesses high yield strength. Simplified static simulation shows a maximum equivalent stress of approximately 60.70 MPa under a 40 kN central limit load and approximately 64.33 MPa under a 32 kN, 3 mm off-center load, both maintaining relatively high static strength. Strength margin; eight circumferential strain gauges help improve sensitivity and reduce output deviations caused by off-center loading, bending moment, and local temperature differences; the ring brake load force sensor is fixedly installed with stationary cable exit, avoiding wear, torsion, and signal interruption of the slip ring and moving cable; the built-in transmitter board shortens the transmission distance of weak signals, improves signal anti-interference capability and feedback stability; four-channel independent load feedback supports brake force closed-loop control, load balancing, anomaly identification, and condition monitoring; stainless steel housing, high-temperature silicon-based potting, polyurethane protection, and PTFE cable improve environmental adaptability; the system can record the load history of each channel, providing a data basis for wear trend analysis, maintenance decisions, and predictive diagnosis.

[0070] Example 5 This embodiment uses the electric cylinder base of this application. The electric cylinder base is equipped with four sets of electric actuation channels. Each channel is equipped with an electric mechanism, a set of gear transmission components, a spline shaft, a set of GQ14×3 ball screw nut pair, an 81705 cylindrical thrust roller bearing, and a ring brake load force sensor with a rated load of 16kN.

[0071] The ring sensor is fixed to the electric cylinder base by two mounting ears, and the ball screw nut pair follows from it. 26. The central through hole passes through, the cylindrical thrust roller bearing is in contact with the axial force surface of the annular brake load force sensor, the ball screw nut pair maintains a radial clearance with the inner hole of the annular brake load force sensor, and the sensor cable is radially led out and fixed to the electric cylinder seat cable channel and connected to the electrical connector.

[0072] The controller drives four electric mechanisms according to the set target load. When the ball screw nut pair generates axial reaction force, the thrust bearing transmits the reaction force to the sensor ring elastic body. The bridge signal output by the eight strain gauges is conditioned by the built-in transmitter board and then input to the controller. The controller adjusts the four channels respectively to make the load of each channel match the target load.

[0073] If independent wiring is permitted for the eight strain gauges, they can be configured into two independent bridge-type detection circuits, with each bridge circuit outputting a corresponding axial load signal. The two bridge circuits can share the same annular elastomer or be connected to independent signal conditioning channels respectively.

[0074] During normal operation, the controller compares the zero point, sensitivity, and real-time load difference between the two sets of bridge circuits. When the difference exceeds the set threshold, the system determines that there may be an abnormality in the strain gauge, lead wire, or conditioning circuit, and adopts a reliable channel for degraded operation or issues a maintenance prompt. This scheme does not change the basic mechanical installation relationship of the sensor.

[0075] When the load on a certain channel is significantly lower than that on other channels and its motor command continues to increase, the system determines that the channel may be unloaded, have a loose connection, or have a transmission failure. When the load on a certain channel exceeds the threshold or the growth rate is abnormal, the system performs load limiting or stops the channel and adjusts other channels according to the safety policy.

[0076] With the above configuration, this embodiment can directly detect the actual brake load of each channel while maintaining the compact structure of the electric cylinder base, and achieve closed-loop adjustment, load balancing and fault identification.

[0077] The preferred embodiments of this application have been described in detail above. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application.

[0078] Many other changes and modifications can be made without departing from the concept and scope of this application. It should be understood that this application is not limited to the specific embodiments, and the scope of this application is defined by the appended claims.

Claims

1. A high-reliability electric braking system integrating brake load detection, characterized in that: It includes an electric cylinder base (1) and four sets of electric actuation channels (2) set on the electric cylinder base (1). The four sets of electric actuation channels (2) are symmetrically arranged around the central area of ​​the electric cylinder base (1). Each set of electric actuation channels (2) generates axial load independently and is equipped with an independent annular brake load force sensor (3). The annular brake load force sensor (3) is connected to an external controller. Each set of the electric actuation channel (2) includes at least an electric mechanism (2-1), a transmission assembly, a splined shaft (2-4), a ball screw nut pair (2-5), a cylindrical thrust roller bearing (2-6), and a brake output end (2-7). The axis of each set of the electric mechanism (2-1) is offset from the axis of the corresponding ball screw nut pair (2-5). The torque output by the electric mechanism (2-1) is transmitted to the ball screw nut pair (2-5) through the transmission assembly. One end of the screw shaft of the ball screw nut pair (2-5) is inserted into the splined shaft (2-4), and the other end of the screw shaft of the ball screw nut pair (2-5) is connected to the brake output end (2-7) to generate an axial load. The splined shaft (2-4) is coaxially arranged with the ball screw nut pair (2-5), and the end of the splined shaft (2-4) is fixed on the electric cylinder seat (1). The annular brake load force sensor (3) is fixedly installed inside the electric cylinder seat (1), and the annular brake load force sensor (3) is sleeved on the outer periphery of the ball screw nut pair (2-5). The cylindrical thrust roller bearing (2-6) is located between the ball screw nut pair (2-5) and the axial force-bearing surface of the annular brake load force sensor (3).

2. The high-reliability electric braking system with integrated brake load detection according to claim 1, characterized in that: The transmission assembly includes a coupling gear (2-2) and an intermediate coupling gear (2-3). The drive gear of the electric mechanism (2-1) meshes with the coupling gear (2-2), the coupling gear (2-2) meshes with the intermediate coupling gear (2-3), and the intermediate coupling gear (2-3) meshes with the outer circumference of the nut of the ball screw nut pair (2-5).

3. The high-reliability electric braking system with integrated brake load detection according to claim 1, characterized in that: The cylindrical thrust roller bearing (2-6) is located on the right end face of the nut of the ball screw nut pair (2-5), and the cylindrical thrust roller bearing (2-6) is located on the left end face of the annular brake load force sensor (3).

4. The high-reliability electric braking system with integrated brake load detection according to claim 1, characterized in that: One end of the spline shaft (2-4) is inserted into the center of the ball screw nut pair (2-5), and the other end of the spline shaft (2-4) is fixed on the electric cylinder seat (1) by a mounting flange. The ball screw nut pair (2-5) moves axially to output axial load.

5. A high-reliability electric braking system with integrated brake load detection according to claim 1, characterized in that: The annular brake load force sensor (3) has an annular structure. The central through hole of the annular brake load force sensor (3) is coaxial with the ball screw nut pair (2-5). A radial gap is provided between the central through hole of the annular brake load force sensor (3) and the ball screw nut pair (2-5). The size of the radial gap is greater than 0.5mm. The radial gap prevents the radial runout and surface friction of the ball screw nut pair (2-5) from being directly applied to the annular brake load force sensor (3).

6. A high-reliability electric braking system with integrated brake load detection according to claim 5, characterized in that: The annular brake load force sensor (3) includes a housing (3-1), an annular elastomer (3-2), a cable (3-3), eight strain gauges (3-4), a transmitter plate (3-5), and a high-temperature potting material (3-6). The annular elastomer (3-2) is disposed inside the housing (3-1). The eight strain gauges (3-4) are arranged circumferentially along the annular elastomer (3-2) to form at least one bridge strain measurement circuit. The transmitter plate (3-5) is disposed inside the housing (3-1). The eight strain gauges (3-4) are electrically connected to the transmitter plate (3-5) respectively. The transmitter plate (3-5) is electrically connected to the cable (3-3). The cable (3-3) is radially led out from the housing (3-1) and fixed in the cable channel of the electric cylinder seat (1) and connected to the controller. The transmitter plate (3-5), the strain gauge (3-4) leads, and the welding parts are fixed and sealed by the high-temperature potting material (3-6).

7. A high-reliability electric braking system with integrated brake load detection according to claim 6, characterized in that: The outer casing (3-1) is provided with mounting ears (3-1-1) on opposite sides. The two mounting ears (3-1-1) are fixed to the electric cylinder seat (1) by two screws. The outer casing (3-1) and cable (3-3) of the annular brake load force sensor (3) remain stationary during braking. The outer shell (3-1) is made of 304 stainless steel, and the annular elastomer (3-2) is made of 17-4PH precipitation hardening stainless steel.

8. A highly reliable electric braking method integrating brake load detection, characterized in that, The braking operation using the high-reliability electric braking system with integrated brake load detection as described in claim 6 specifically includes the following steps: Step 1: The controller receives the braking command and distributes the target load to the four sets of electric actuation channels (2). Step 2: The electric mechanism (2-1) starts, and the output torque is transmitted to the ball screw nut pair (2-5) through the transmission assembly and spline shaft (2-4). Step 3: The ball screw nut pair (2-5) converts the rotational motion into axial motion, forming a braking force and a corresponding axial reaction force. The braking force acts on the brake output end, generating an axial load. Step 4: The axial reaction force is applied to the annular elastic body (3-2) of the annular brake load force sensor (3) via the cylindrical thrust roller bearing (2-6). The strain gauge (3-4) converts the strain of the annular elastic body (3-2) into a bridge circuit electrical signal. Step 5: The transmitter board (3-5) amplifies, filters and compensates the signal, and outputs the measured load Fi of the corresponding electric actuation channel (2) to the controller; Step 6: The controller adjusts the motor commands based on the load error between the target load and the measured load, and performs load balancing between channels; Step 7: If overload, no load, sudden load change, or inconsistency among multiple channels is detected, the controller will execute alarm, load limiting, compensation, or safety mode. Step 8: When the brake is released, the controller drives each electric actuation channel (2) to move in the opposite direction and confirms whether the braking force is released as expected through the load signal.

9. A high-reliability electric braking method with integrated brake load detection according to claim 8, characterized in that: The controller is used to calculate the total measured load, Fsum=F1+F2+F3+F4, and compare the deviation between the measured load of any electric actuator channel (2) and the multi-channel average load Favg. The load error Ei = Fset,i - Fi, i = 1, 2, 3, 4, where Fset,i is the target load and Fi is the measured load of the corresponding annular brake load force sensor (3). The controller adjusts the drive command of the electric mechanism (2-1) according to the load error so that the measured load of each electric actuator channel (2) approaches the target load.

10. A high-reliability electric braking method with integrated brake load detection according to claim 9, characterized in that: The measured load of the annular brake load force sensor (3) is Fi=Kf·Ui, where Ui is the output of each transmitter board (3-5) and Kf is the force coefficient obtained by standard load calibration.

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