Electromechanical brake device

Abstract

This invention relates to a braking structure. An electromechanical braking device includes a motor drive structure, a reduction and torque-increasing structure, a linear motion structure, and a braking actuation structure connected in sequence. A piston is provided between the linear motion structure and the braking actuation structure. One end of the piston is in contact with a friction plate of the braking actuation structure. An elastic element is provided at the output end of the output component of the linear motion structure. A pressure sensor is provided between the elastic element and the piston. The signal from the pressure sensor is transmitted to a controller, which controls the forward and reverse rotation of the motor. This invention provides an electromechanical braking device with a simple structure that effectively prevents motor stalling, facilitates adjustment of braking force, and enables precise adjustment of the brake disc. It solves the technical problem in existing electromechanical braking devices that are prone to motor stalling, resulting in overheating and adverse effects on motor performance, and increasing the difficulty of braking force adjustment.

Description

Technical Field

[0001] This invention relates to a transmission structure, and more particularly to an electromechanical braking device. Background Technology

[0002] With the continuous development of motor, battery, and electric drive technologies, more and more drive-by-wire technologies have emerged to replace traditional mechanical control technologies. Electromechanical Brake (EMB) systems, due to their advantages such as intelligence, lightweight design, and high safety, are gradually becoming the preferred braking technology for the next generation of electric vehicles.

[0003] Compared to traditional hydraulic braking, the EMB system adopts an electromechanical integrated design, eliminating complex hydraulic lines and resulting in a simpler structure. It is also cleaner and more environmentally friendly. Because it does not rely on brake fluid, the EMB system avoids braking delays and offers faster response times. Furthermore, the EMB system can precisely control the required braking force, significantly improving vehicle safety and reliability. The EMB system mainly consists of a motor, reducer, clamping device, calipers, and controller. As the drive system, the motor continues to rotate after braking, which can lead to motor stall. When the motor stalls, not only does the heat generated rise rapidly, adversely affecting motor performance, but it also greatly increases the difficulty of adjusting the braking force. Summary of the Invention

[0004] This invention provides an electromechanical braking device with a simple structure that can effectively prevent motor stalling, facilitate adjustment of braking force, and achieve precise adjustment of the brake disc. It solves the technical problem in the prior art where motor mechanical braking devices are prone to motor stalling, resulting in heat generation that adversely affects motor performance and increases the difficulty of braking force adjustment.

[0005] The above-mentioned technical problem of the present invention is solved by the following technical solution: an electromechanical braking device includes a motor drive structure, a reduction and torque amplification structure, a linear motion structure, and a braking execution structure connected in sequence. A piston is provided between the linear motion structure and the braking execution structure. One end of the piston is connected to the friction plate of the braking execution structure. An elastic element is provided at the output end of the output component of the linear motion structure. A pressure sensor is provided between the elastic element and the piston. The signal from the pressure sensor is transmitted to a controller, which controls the forward and reverse rotation of the motor. The drive mechanism is fixed to the braking execution mechanism by bolts. The reduction and torque amplification mechanism and the linear motion mechanism are installed inside the braking execution mechanism, which is mounted on the wheel. The linear motion structure drives the two friction plates of the braking execution structure to move closer together, achieving braking. After braking, due to the presence of the elastic element, the motor can still rotate. However, the linear motion caused by the rotation of the motor only compresses the elastic element. The elastic element is connected to the pressure sensor, which can sense changes in pressure. The controller receives the feedback from the pressure sensor and controls the motor to rotate forward or backward to adjust the deformation of the elastic element, thereby achieving precise adjustment of the braking force. At the same time, it can also effectively prevent the motor from stalling and improve the service life of the motor. The sensor is installed between the elastic element and the piston to measure the final braking force acting on the brake disc, thereby achieving precise adjustment of the braking force and avoiding inaccurate adjustment of the braking force due to friction loss of the elastic element itself.

[0006] Preferably, the linear motion structure is a planetary roller screw structure, which includes a screw, rollers, and a nut. The output component is the nut, the end of which is connected to an elastic element, and one end of the screw is connected to the output component of the speed reduction and torque amplification structure. The planetary roller screw structure can effectively convert rotary motion into linear motion, and can also effectively reduce the size of the mechanism, has a strong load-bearing capacity, and improves the overall reliability of the mechanism.

[0007] Preferably, the nut is integrally formed with a boss, and the piston has an annular groove at its end. The two ends of the annular groove become the endpoints that limit the axial movement stroke of the nut. The first limiting point is the contact position between the annular groove and the boss, which ensures the initial position of the nut and the piston; the second limiting point is the rightmost end of the annular groove, which prevents irreversible deformation of the elastic element, thus preventing the elastic element from failing.

[0008] Preferably, the stroke of the boss within the groove does not exceed the maximum allowable deformation of the elastic element. This ensures the effectiveness of the elastic element and prevents it from failing due to excessive movement.

[0009] Preferably, the lead screw has a bearing mounting surface at one end outside the nut, and a thrust bearing is sleeved on the lead screw, located between the brake caliper and the lead screw, with its end face abutting against the bearing mounting surface. The thrust bearing is used to withstand the reaction force from the planetary roller screw pair.

[0010] Preferably, the elastic element is composed of multiple butterfly springs stacked together, and the spring constant is greater than 10. 3 N / mm. Due to the limited internal space of the brake, the elastic element must have a high elastic coefficient to meet the high braking force requirements of the braking system. Therefore, the preferred elastic element is multiple disc springs stacked together or stacked and then combined. Stacking disc springs and then combining them can multiply the total deformation of the elastic element under the same braking force. The increased total deformation is ultimately reflected in more rotations of the motor, which is beneficial for motor control. Stacking means that multiple springs are interlocked, and the length of the elastic element remains unchanged after stacking. Combining means that multiple springs are axially connected, and the length of the combined spring is the length of the individual springs connected together.

[0011] Preferably, the motor drive structure includes a motor and an input gear.

[0012] Preferably, the speed reduction and torque amplification structure includes an intermediate gear and an output gear that mesh with each other. The intermediate gear meshes with the input gear in the motor drive structure, and the output gear is connected to the lead screw of the linear motion structure via internal and external splines. This ensures the normal operation of the structure.

[0013] Preferably, the piston has a pressure sensor mounting groove in the middle, one end of the pressure sensor is connected to the elastic element, and the pressure sensor, elastic element and piston are arranged coaxially.

[0014] Therefore, the electromechanical braking device of the present invention has the following advantages: An elastic element is provided between the nut and the piston, and the nut and piston can move axially relative to each other. During braking, the elastic element deforms under the braking force, and this deformation is converted into an axial displacement of the nut relative to the piston, ultimately manifesting as the rotation of the motor. This means the motor rotates continuously during braking without stalling. A force sensor is installed between the piston and the elastic element to detect the braking force exerted by the elastic element on the piston. The rotary-linear motion conversion mechanism is designed as a planetary roller screw pair, which effectively reduces the size of the mechanism, has a strong load-bearing capacity, and improves the overall reliability of the mechanism. Attached Figure Description

[0015] Figure 1 This is a cross-sectional view of an electromechanical braking device.

[0016] Figure 2This is an enlarged view of the piston and planetary roller screw structure connection.

[0017] Figure 3 This is an enlarged view of the piston and nut assembly. Detailed Implementation

[0018] The technical solution of the invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0019] Example 1:

[0020] like Figure 1 and 2 As shown in Figure 3, an electromechanical braking device includes an end cap 3 and a brake caliper body 16. The end cap 3 and the brake caliper body 16 form a receiving cavity, in which a motor drive structure is installed. The motor drive structure is connected to a speed reduction and torque amplification structure, which is connected to a linear motion structure. The linear motion structure is connected to a braking actuation structure. A piston 13 and an elastic element 14 are installed between the linear motion structure and the braking actuation structure. A pressure sensor 15 is coaxially arranged at the center of the piston 13.

[0021] The motor drive structure includes a drive motor 1, and an input gear 2 is sleeved on the output shaft of the drive motor 1.

[0022] The speed reduction and torque amplification structure includes an intermediate gear 4 and an output gear 5 that mesh with each other, wherein the intermediate gear 4 meshes with the input gear 2 in the motor drive structure.

[0023] The linear motion structure is a planetary roller screw structure, which includes a centrally located screw 6. An output gear 5 is connected to the screw via internal and external splines 21. Rollers 11 are located around the screw 6, and nuts 12 are fitted over the rollers 11. Internal gear rings 9, cages 10, and snap rings are mounted at both ends of the rollers 11. The rollers 11 mesh with the nuts 12 and the screw 6 via threaded connections. The internal gear rings 9 are positioned at both ends of the nuts 12 and mesh with the gears at both ends of the rollers 11. The cage 10 is mounted on one side of the internal gear ring 9 and has the same number of locating holes as the rollers to prevent deflection during movement. The snap rings are located on the outside of the cage to prevent axial movement of the cage. The portion of the screw 6 outside the nuts 12 has a bearing mounting surface 8. A thrust bearing 7 is fitted onto the screw 6 and is installed between the screw 6 and the brake caliper body 16 to withstand the reaction force from the planetary roller screw pair. The end of the lead screw is connected to the output gear 5 via spline 21.

[0024] An annular protrusion 22 is formed on the outer circumferential surface of the nut 12. A groove 23 is formed at the end of the piston 13. The outer diameter of the protrusion 22 is smaller than the inner diameter of the groove 23. The two ends of the groove 23 are the starting point and the ending point of the movement of the protrusion. The stroke of the nut 12 is L, which is less than the maximum allowable deformation of the elastic element 14.

[0025] Multiple butterfly spring composite elastic elements 14 are abutted at the end of the nut 12. One end of the elastic element 14 abuts against the end face of the nut 12, and the other end of the elastic element 14 abuts against the pressure sensor 15. The elastic coefficient of the elastic element 14 is greater than 10. 3 N / mm.

[0026] The braking actuator includes a left friction pad 18, a right friction pad 17, and a brake caliper 16. A piston 13 is connected to the left friction pad 18, and a rectangular sealing ring 20 and a dustproof sealing ring 19 are fitted over the piston 13.

[0027] Working principle:

[0028] Vehicle braking can be divided into three stages. The first stage involves eliminating brake clearance. Upon receiving the braking command, the controller activates the motor, which, through a reduction and torque amplification mechanism, transmits the motor's output torque and speed to the linear motion structure. Under the action of the planetary ball screw pair, the left friction pad moves axially towards the brake disc. When the left friction pad contacts the brake disc, the brake caliper begins to move axially until both friction pads are tightly against the brake disc, completely eliminating the brake assembly clearance. During this process, only internal friction needs to be overcome. The elastic element is formed by multiple disc springs with high elastic coefficients, either combined or stacked. Therefore, there is almost no relative axial displacement between the nut and the piston.

[0029] The second stage: Braking process; After the gap in the braking device is completely eliminated, the vehicle enters the braking and deceleration stage. The motor continues to work, and the output torque is transmitted to the piston through the reduction and torque amplification mechanism. At this time, since the friction pads are tightly attached to the brake disc, the piston does not move linearly. In existing solutions, the motor starts to stall, and the braking force can only be adjusted by regulating the motor current. However, this method has low adjustment accuracy, and stalling will adversely affect the performance of the motor. In this application, a pressure sensor and an elastic element are designed between the piston and the nut. The axial movement of the nut towards the piston end is restricted by the cooperation of the protrusion on the nut and the groove on the piston. The nut can also move axially towards the piston end. During this process, the lead screw rotates through the cooperation of the external spline at one end with the internal spline of the output gear of the reduction and torque amplification mechanism. The torque transmitted from the motor end is converted into thrust through the planetary roller screw pair. The nut transmits the thrust to the elastic element, and the elastic element applies the force to the pressure sensor and the piston, ultimately realizing the braking process. When the force is transmitted to the elastic element, the elastic element will deform, so the nut will move linearly towards the piston end, that is, the motor does not need to stall and continues to rotate. When the braking force needs to be adjusted, the pressure sensor detects the force acting on the piston and feeds it back to the controller. The controller then controls the motor to rotate forward or backward according to the braking force target, ultimately adjusting the braking force by regulating the deformation of the elastic element. The force transmission route during braking is as follows: torque output by the motor → reduction and torque amplification mechanism → planetary roller screw pair → elastic element → pressure sensor and piston → friction pads → brake disc.

[0030] The third stage: brake release stage; after the vehicle completes the braking purpose, the motor reverses, and the deceleration and torque increase mechanism drives the lead screw to reverse, the nut moves axially away from the piston end, the elastic element returns to its original state, when the nut moves to the end of the piston groove, the piston assembly moves away from the friction plate, the friction plate moves away from the brake disc, and the brake is released.

[0031] The specific embodiments described herein are merely illustrative of the concept of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. An electromechanical braking device, comprising a motor drive structure, a speed reduction and torque amplification structure, a linear motion structure, and a braking actuation structure connected in sequence, characterized in that: A piston is provided between the linear motion structure and the braking actuation structure. One end of the piston is connected to the friction plate of the braking actuation structure. An elastic element is provided at the output end of the output component of the linear motion structure. A pressure sensor is provided between the elastic element and the piston. The signal from the pressure sensor is transmitted to the controller, which controls the forward and reverse rotation of the motor. The linear motion structure is a planetary roller screw structure, which includes a screw, rollers, and a nut. The output component is the nut, and the end of the nut is connected to the elastic element. One end of the screw is connected to the output component of the speed reduction and torque amplification structure. A boss is integrally formed on the outside of the nut, and an annular groove is provided at the end of the piston. The boss moves within the groove.

2. The electromechanical braking device according to claim 1, characterized in that: The stroke of the boss moving within the groove is not greater than the maximum allowable deformation of the elastic element.

3. The electromechanical braking device according to claim 1, characterized in that: The lead screw has a bearing mounting surface at one end outside the nut. A thrust bearing is sleeved on the lead screw, and the thrust bearing is located between the brake caliper and the lead screw. The end face of the thrust bearing abuts against the bearing mounting surface.

4. An electromechanical braking device according to any one of claims 1 to 3, characterized in that: The elastic element is composed of multiple butterfly springs stacked together, and the spring constant is greater than 10. 3 N / mm.

5. An electromechanical braking device according to any one of claims 1 to 3, characterized in that: The motor drive structure includes a motor and an input gear.

6. An electromechanical braking device according to any one of claims 1 to 3, characterized in that: The aforementioned speed reduction and torque amplification structure includes an intermediate gear and an output gear that mesh with each other. The intermediate gear meshes with the input gear in the motor drive structure, and the output gear is connected to the lead screw of the linear motion structure via internal and external splines.

7. An electromechanical braking device according to any one of claims 1 to 3, characterized in that: The piston has a pressure sensor mounting groove in the middle, one end of the pressure sensor is connected to the elastic element, and the pressure sensor, elastic element and piston are arranged coaxially.

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