An electromechanical braking system based on gear system for coupling driving and parking brakes

Abstract

This utility model belongs to the field of automotive electromechanical braking, and provides an electromechanical braking system based on a gear system that couples driving and parking brakes. The system consists of a driving brake motor, a three-gear system, a planetary gear system, a parking brake motor, and a two-stage worm gear assembly. The driving and parking motors are arranged in parallel. The torque from the driving motor is sequentially reduced by the three-gear system and then input to the sun gear of the planetary gear system. The gear ring is fixed. The braking torque is output from the planetary carrier output shaft. The parking motor drives the worm gear through the two-stage worm gear. The teeth on the end face of the worm gear can be pressed and meshed with the teeth on the end face of the planetary carrier to achieve parking torque transmission. Both torque paths share the same planetary carrier output shaft, resulting in a compact structure, large transmission ratio, fast response, and high redundancy. It is suitable for highly integrated electromechanical braking systems in new energy and autonomous vehicles.

Description

Technical Field

[0001] This utility model relates to automotive electromechanical braking systems, specifically to an electromechanical braking system based on a gear system that couples driving and parking brakes. Background Technology

[0002] With the increasing integration of chassis drive-by-wire and mechatronics, electromechanical braking systems are gradually replacing traditional hydraulic braking systems.

[0003] The core design concept of electromechanical braking systems is to directly generate braking force using a motor-driven acceleration and deceleration mechanism and a motion conversion mechanism, eliminating brake fluid and achieving complete electronic control. Existing technologies generally suffer from the following systemic defects:

[0004] The transmission ratio is small and the motor is large. Due to the space limitation of the wheel rim, the reduction mechanism can only be made in two stages. In order to compensate for the insufficient transmission ratio, only a high-speed and high-torque motor can be selected, resulting in a large outer diameter, long axial length and heavy mass of the motor, which seriously occupies the internal space of the wheel hub and makes it difficult to arrange with components such as suspension and steering tie rods.

[0005] The structure is large and the installation is complex. It typically uses two sets of housings, two sets of bearings, and two sets of seals, resulting in a generally large total axial length. The brakes require thickened flanges or additional supports, which increases the unsprung mass of the vehicle. During assembly, the backlash of the gears on the traveling side and the backlash of the worm gear on the parking side must be adjusted separately, resulting in large cumulative errors and a long process cycle, much longer than that of traditional hydraulic brakes.

[0006] Slow response and low control precision. The overlapping meshing clearances of multi-stage cylindrical gears result in a large idle stroke, causing the clamping force build-up time to fail to meet the duration requirements of automatic emergency braking.

[0007] Insufficient reliability and redundancy. The standalone parking brake is prone to triggering under overheating conditions, reducing torque and power. The lack of redundancy mode fails to meet the requirements of braking safety regulations.

[0008] Therefore, the aforementioned defects have become a bottleneck restricting the large-scale mass production of EMB. Thus, there is an urgent need for a coupled transmission solution with a single output shaft, high reduction ratio, and compatibility with high-efficiency parking, to simultaneously meet the multiple requirements of high response, high precision, high reliability, lightweight design, and low cost. Utility Model Content

[0009] In view of the shortcomings of the prior art, the purpose of this utility model is to provide an electromechanical braking system based on a gear system that couples driving and parking brakes, so as to solve the problems mentioned in the background art.

[0010] To achieve the above objectives, this utility model provides the following technical solution:

[0011] An electromechanical braking system based on a gear train coupling vehicle and parking brake includes a vehicle brake motor, a three-stage gear train, a planetary gear train, a parking brake motor, and their transmission components. The vehicle brake motor and the parking brake motor are arranged in parallel. The three-stage gear train includes a first-stage gear, a second-stage gear, and a third-stage gear. The third-stage gear is mounted on the sun gear input shaft of the planetary gear train. The other end of the sun gear input shaft is fixedly mounted with a sun gear, which meshes sequentially with planet gears and a ring gear. The ring gear is fixedly mounted. The planetary gear train outputs braking torque through the planetary carrier output shaft at one end of the planetary carrier. The parking brake transmission component drives the second-stage parking reduction worm wheel to rotate through the rotation of the second-stage parking reduction worm gear. The mating surfaces of the second-stage parking reduction worm wheel and the planetary carrier are respectively provided with worm wheel end face teeth and planetary carrier end face teeth. The torque is transmitted and output from the planetary carrier output shaft through the contact and pressing of the worm wheel end face teeth and the planetary carrier end face teeth. The vehicle brake motor and the parking brake motor together output torque to the planetary carrier output shaft.

[0012] The first stage gear of the three-stage gear system is fixedly mounted on the output shaft of the vehicle brake motor. The two ends of the second stage gear are fixedly provided with second stage gear mounting bearings. The third stage gear is fixedly mounted on the sun gear input shaft of the planetary gear system. One end of the sun gear input shaft is provided with a third stage gear mounting bearing. The first stage gear, the second stage gear, and the third stage gear mesh in sequence.

[0013] The planetary gear system includes a ring gear, a sun gear, planet gears, and a planet carrier. The sun gear meshes with the planet gears, and the planet gears are fixedly mounted on the planet carrier and mesh with the ring gear. The rotation of the planet carrier drives the output shaft of the planet carrier, which is fixed coaxially at its end, to output braking torque. The third-stage gear is provided with a gear groove, the inner diameter of which is larger than the outer diameter of the ring gear. The planetary gear system is embedded in the gear groove cavity.

[0014] The gear ring is provided with a connecting key on its exterior and is assembled and fixed with the keyway on the gearbox housing.

[0015] Preferably, the transmission assembly includes a parking primary reduction worm gear, a parking primary reduction worm wheel, a parking secondary reduction worm gear, a parking secondary reduction worm wheel, and a parking secondary reduction worm wheel mounting bearing. The parking primary reduction worm gear is fixedly mounted on the parking brake motor. The parking primary reduction worm gear meshes with the parking primary reduction worm wheel, and the parking secondary reduction worm gear meshes with the parking secondary reduction worm wheel in sequence. Both ends of the worm gear are fixed by the parking secondary reduction worm gear fixing bearing.

[0016] Preferably, the third-stage gear is mounted on the sun gear input shaft, while the parking secondary reduction worm gear is sleeved on the planetary carrier output shaft. The parking secondary reduction worm gear mounting bearing is mounted on the planetary carrier output shaft. The mating surfaces of the parking secondary reduction worm gear and the planetary carrier are respectively provided with worm gear end face teeth and planetary carrier end face teeth. The number of end face teeth is two or more and symmetrically arranged along the circumference, and the worm gear end face teeth and planetary carrier end face teeth are used in pairs.

[0017] Preferably, the first-stage gear is fixedly connected to the output shaft of the vehicle brake motor, the second-stage gear is fixedly connected to its mounting shaft, or is forged into one piece, with second-stage gear mounting bearings or bushings installed at both ends of the mounting shaft, and the third-stage gear is fixedly connected to the sun gear input shaft. At one end of the sun gear input shaft, the third-stage gear mounting bearing is assembled, and the other end is connected to the sun gear. The sun gear and the sun gear input shaft are integrally formed or fixed by interference fit.

[0018] The parking brake secondary reduction worm gear is connected to the planetary carrier output shaft via a bearing or bushing. The end face teeth of the parking brake secondary reduction worm gear are in close contact with the end face teeth of the planetary carrier. The working rotation angle of the planetary carrier of the triple gear system is less than 180 degrees.

[0019] The parking secondary reduction worm gear rotates coaxially with the planetary carrier output shaft. During parking braking, torque is transmitted through the rotation and compression of the worm gear end face teeth and the planetary carrier end face teeth. The working rotation angle of the parking secondary reduction worm gear is less than 180 degrees.

[0020] Preferably, the parking primary reduction worm gear is fixedly connected to the output shaft of the parking brake motor, the parking primary reduction worm wheel is fixedly mounted on the parking secondary reduction worm gear via a keyway or spline, the parking secondary reduction worm gear is provided with parking secondary reduction worm gear fixed bearings at both ends, and the parking secondary reduction worm gear is fixedly mounted to the parking primary reduction worm wheel or forged into one piece.

[0021] Compared with existing technologies, this invention integrates a triple gear train, a planetary gear train, and a worm gear transmission mechanism into the transmission part of an electromechanical braking system. This fully leverages the advantages of various mechanical transmission methods, forming a highly integrated, efficient, and reliable transmission solution. Its main advantages are as follows:

[0022] The system features a large transmission ratio and a compact structure. The triple gear system expands the speed ratio range and increases output torque, while the planetary gear system achieves a large transmission ratio within a small volume, making it suitable for actuators in electromechanical braking systems with limited wheel-side space. The worm gear has a self-locking characteristic, preventing reverse rotation in the event of power failure or motor failure, thus enabling parking braking or fail-safe protection. The overall system design achieves a large reduction ratio, small size, and mechanical self-locking, meeting the dual requirements of high output torque and space constraints in electromechanical braking systems.

[0023] Fast response and high control precision. Multi-stage gear transmissions, including triple gear and planetary gear systems, feature high speed ratios and high rigidity, reducing transmission lag. The transmission system, in conjunction with motor control, can achieve millisecond-level response and supports braking system functions such as ABS and ESC.

[0024] High reliability and redundancy design potential. The planetary gear system has a uniform load distribution, strong shock resistance, and is suitable for high-frequency braking. The mechanical self-locking of the worm gear can serve as a safety backup in case of electronic failure, meeting functional safety requirements.

[0025] Highly modular and scalable. The gear transmission mechanism can be modularly combined, allowing for flexible adjustment of the transmission ratio and output force according to different vehicle models, such as sedans, SUVs, or commercial vehicles. It is easy to integrate force sensors or torque sensors to achieve closed-loop force control and support intelligent driving algorithms.

[0026] In summary, the combination of triple gears, planetary gears, and worm gears adopted in this utility model achieves an optimized design in the electromechanical braking system with a large reduction ratio, high rigidity, self-locking safety, fast response, and small size. It is a highly advantageous solution in current high-level autonomous driving and electric chassis.

[0027] The detailed structure of this utility model will be further described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of an electromechanical braking system that couples driving and parking brakes according to this utility model;

[0029] Figure 2 This is a schematic diagram of the vehicle and parking brake coupling assembly of this utility model;

[0030] Figure 3 This is a schematic diagram of the three-gear transmission mechanism for the vehicle brake of this utility model;

[0031] Figure 4 This is a schematic diagram of the transmission assembly structure of the three-gear system for vehicle braking according to this utility model;

[0032] Figure 5 This is a schematic diagram of the planetary gear transmission assembly of this utility model.

[0033] in:

[0034] 1. Service brake motor; 2. First stage gear; 3. Second stage gear; 4. Second stage gear mounting bearing; 5. Third stage gear mounting bearing; 6. Third stage gear; 7. Sun gear input shaft; 8. Gear ring; 9. Planetary gears; 10. Planetary carrier; 11. Parking secondary reduction worm gear; 12. Parking secondary reduction worm wheel; 13. Parking primary reduction worm wheel; 14. Parking primary reduction worm gear; 15. Parking brake motor; 16. Parking secondary reduction worm wheel mounting bearing; 17. Planetary carrier output shaft; 18. Worm wheel end face teeth; 19. Planetary carrier end face teeth; 20. Internal gear ring retainer; 21. Sun gear; 22. Parking secondary reduction worm gear retaining bearing; 23. Gear groove; 40. Triple gear train; 50. Planetary gear train. Detailed Implementation

[0035] like Figure 1-5 As shown, an electromechanical braking system coupling driving and parking brakes includes a driving brake motor 1, a parking brake motor 15, a three-stage gear train 40, a planetary gear train 50, a two-stage worm gear and mounting bearing assembly, etc. This invention alters the direction of braking force transmission by arranging the parking brake motor 15 parallel to the driving brake motor 1, using a three-stage gear train for the driving brake, and employing a high-ratio two-stage worm gear transmission mechanism for the parking brake. This allows the system to influence the third-stage gear 6 by affecting the planetary gear transmission. The third-stage gear 6 has a recessed recess housing the planetary gear train, reducing the structural dimensions, increasing the system's transmission ratio, achieving system miniaturization and integration, which helps reduce weight and increase braking torque.

[0036] The triple gear system 40 includes a first-stage gear 2, a second-stage gear 3, and a third-stage gear 6. The first-stage gear 2 is fixed on the output shaft of the service brake motor 1. The two ends of the second-stage gear 2 are fixed by the second-stage gear mounting bearing 4. The first-stage gear 2, the second-stage gear 3, and the third-stage gear 6 mesh sequentially. A sun gear input shaft 7 is fixedly mounted on the third-stage gear 6.

[0037] The two-stage worm gear transmission mechanism includes a parking primary reduction worm 14, a parking primary reduction worm wheel 13, a parking secondary reduction worm 11, a parking secondary reduction worm wheel 12, and a parking secondary reduction worm wheel mounting bearing 16. The parking primary reduction worm 14 is fixedly mounted on the parking brake motor 15. The parking primary reduction worm 14 meshes with the parking primary reduction worm wheel 13, and the parking secondary reduction worm 11 meshes with the parking secondary reduction worm wheel 12 in sequence. Both ends of the worm are fixed by the parking secondary reduction worm wheel fixing bearing 22.

[0038] The third-stage gear 6 is mounted on the sun gear input shaft 7. The third-stage gear 6 drives the sun gear 21, which in turn drives the planet gears 9. The planet gears 9 then drive the planet carrier 10 to complete power transmission. The parking secondary reduction input worm gear 11 is mounted on the planet carrier output shaft 17. Both the parking secondary reduction input worm gear 11 and the planet carrier 10 have end face teeth on their mating surfaces. The parking secondary reduction input worm gear 11 transmits power to the planet carrier 10 through these end face teeth. The third-stage gear 6 and the parking secondary reduction input worm gear 11 achieve a coupled design by jointly influencing the planetary gear system 50. This means that either the driving braking torque output or the parking braking torque output can be achieved independently, or the two torques can be superimposed.

[0039] The planetary gear system 50 includes a ring gear 8, a sun gear 21, planet gears 9, and a planet carrier 10. The sun gear 21 is fixedly mounted on the third-stage gear 6 and meshes with the planet gear 9. The planet gear 9 is fixedly mounted on the planet carrier 20 and meshes with the ring gear 8. The rotation of the planet carrier 10 drives the power output shaft 17 fixed at its end to output braking torque. The output rotational torque is converted into linear motion of the brake piston through a motion conversion mechanism, such as a ball screw, thereby pressing the brake disc to generate braking force.

[0040] The third-stage gear 6 of the triple gear system is provided with a gear groove 23. The inner diameter of the groove hole is larger than the outer diameter of the planetary gear ring 8. The planetary gear is embedded in the interior of the third-stage gear 6, which reduces the overall arrangement of the planetary gear system and can reduce the dimension in the height direction by more than 20%, thereby making the transmission system structure more compact. At the same time, the use of the planetary gear system achieves a larger transmission ratio and improves the braking force.

[0041] Specifically, the gear ring 8 is externally fitted with a connecting key 20, which is assembled and fixed to the keyway on the gearbox housing.

[0042] Specifically, the first-stage gear 2 of the service brake is fixedly connected to the output shaft of the service brake motor 1. The second-stage gear 3 is fixedly connected to its mounting shaft via keyways, splines, or other means, or is forged into a single piece. Second-stage gear mounting bearings 4 or bushings are installed at both ends of the mounting shaft to reduce friction and improve efficiency. The third-stage gear 6 is fixedly connected to the sun gear input shaft 7. At one end of the sun gear input shaft 7 is the third-stage gear mounting bearing 5, and at the other end is the sun gear 21. The sun gear 21 and the sun gear input shaft 7 are integrally formed.

[0043] Optionally, the third-stage gear 6 is fixedly connected to the sun gear input shaft 7 by means of splines or keyways, and the sun gear 21 is integrally formed or press-fitted to the third-stage gear 6.

[0044] Specifically, the parking brake secondary reduction worm gear 11 is connected to the planetary carrier output shaft 17 via a bearing or bushing, and the two worm gear end face teeth 18 of the parking brake secondary reduction worm gear 11 are tightly engaged with the two gear end face teeth 19 of the planetary carrier 10. When the vehicle is under service braking, the service brake motor 1 drives the three-stage gear system to work. The parking brake motor 15 serves as a redundant backup and does not need to work synchronously. Furthermore, since the third-stage gear 6 needs to rotate 180 degrees for the two end face teeth of the parking secondary reduction worm gear 11 to contact the other side of the two end face teeth of the planetary carrier 10, the working rotation angle of the third-stage gear 6 in the two-stage reduction mechanism designed in this utility model is less than 180 degrees. The two end face teeth of the parking secondary reduction worm gear 6 and the two end face teeth of the planetary carrier 10 have a clearance margin and will not interfere. Moreover, when the vehicle starts, the parking brake can be released manually or automatically before the service brake. That is, the parking secondary reduction worm gear 11 returns to its initial position first, and then the third-stage gear 6 returns to its initial position. Therefore, the service brake and the parking brake can work independently without affecting each other.

[0045] Preferably, to prevent incorrect installation, the parking secondary reduction worm gear 11 can be provided with end face teeth at both ends, so that there is no need to distinguish the installation direction.

[0046] like Figure 2 As shown, the vehicle and parking brake coupling assembly includes a parking secondary reduction worm gear 11, a third-stage gear 6, and a planetary gear system 50 embedded therein. The two worm gear end face teeth 18 of the parking secondary reduction worm gear 11 and the two gear end face teeth 19 of the planetary carrier are respectively arranged opposite each other at 180 degrees around the circumference and fit tightly together after assembly. The inner diameter of the gear groove of the third-stage gear 6 is larger than the outer diameter of the gear ring 8 of the planetary gear system 50 and is fixedly fitted. The planetary carrier 10 and the power output shaft 17 output braking torque.

[0047] like Figure 5 As shown, the planetary gear transmission assembly mainly includes a sun gear 21, planet gears 9, a ring gear 8, a planet carrier 10, and a power output shaft 17. The rotation of the sun gear 21 inputs the torque transmitted by the service brake motor through a three-stage gear system or a two-stage worm gear system to the parking brake secondary reduction worm gear 11. This rotation drives the planet gears 9 to rotate, and the planet gears rotate around the sun gear 21 and the ring gear 8, which in turn drives the planet carrier 10 to rotate, ultimately causing the power output shaft 17 to rotate.

[0048] Specifically, when the vehicle is performing regular service braking, the service brake motor 1 transmits torque to the sun gear 21 fixed on the third stage gear 6 through the three-stage gear system 40. The rotation of the sun gear 21 drives the planet gears 9 to rotate. The planet gears rotate around the gear ring 8, which drives the planet carrier 10 to rotate, which in turn drives the power output shaft 17 to rotate and output braking torque.

[0049] Specifically, when the vehicle is in regular parking braking mode, the parking brake motor 15 rotates through a two-stage worm gear transmission mechanism to input torque to the second-stage parking reduction worm gear 12. The two end face teeth 18 of the worm gear and the two end face teeth 19 of the planetary carrier 10 are closely engaged and rotate around the planetary carrier output shaft 17 to transmit power torque to the planetary carrier output shaft 17.

[0050] Specifically, the parking first-stage reduction worm gear 14 is fixedly connected to the parking brake motor 15, and the parking first-stage reduction worm wheel 13 is fixedly mounted on the parking second-stage reduction worm gear 11 through a keyway or spline. The parking second-stage reduction worm gear 11 is provided with mounting bearings at both ends.

[0051] Specifically, the parking secondary reduction worm gear 11 and the parking primary reduction worm wheel 13 are forged into one piece.

[0052] Furthermore, when the vehicle requires braking force exceeding that of normal braking under certain special operating conditions, the parking brake motor 15 engages with the parking first-stage reduction worm gear 13 via the parking first-stage reduction worm gear 14, and then inputs parking braking torque through the parking second-stage reduction worm gear 11 and the second-stage reduction worm gear 12 for speed reduction and torque amplification. When the end face teeth of the parking second-stage reduction worm gear 6 contact the end face teeth of the planetary carrier 10, it affects the planetary gear system and thus affects the superimposed torque of the output motor to meet the braking force requirements under extreme braking conditions.

[0053] When the service brake and parking brake are released, the two motors, service brake motor 1 and parking brake motor 15, stop working, and parking is achieved through the parking worm gear self-locking function of the parking brake system.

[0054] Furthermore, when the service brake system fails, the parking brake motor 15 drives the parking secondary reduction worm wheel 12 to rotate through its own worm gear reduction mechanism. When the end face teeth of the parking secondary reduction worm wheel 12 contact the end face teeth of the planetary carrier 10, it drives the planetary gear system to transmit torque, thus still achieving a certain service braking function.

[0055] The above description is a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in this utility model, based on the technical solution and concept of this utility model, should be covered within the protection scope of the claims of this utility model.

Claims

1. An electromechanical braking system based on a gear system for coupling driving and parking brakes, comprising a driving brake motor (1), a three-stage gear system (40), a planetary gear system (50), a parking brake motor (15), and their transmission components, wherein the driving brake motor (1) and the parking brake motor (15) are arranged in parallel, the three-stage gear system (40) includes a first-stage gear (2), a second-stage gear (3), and a third-stage gear (6), wherein the third-stage gear (6) is mounted on the sun gear input shaft (7) of the planetary gear system (50), and a sun gear (21) is fixedly disposed at the other end of the sun gear input shaft (7), which meshes sequentially with a planetary gear (9) and a ring gear (8), the ring gear (8) being fixedly disposed, characterized in that: The planetary gear system (50) outputs braking torque through the planetary carrier output shaft (17) at one end of the planetary carrier (10). The parking brake transmission assembly drives the parking secondary reduction worm wheel (12) to rotate through the rotation of the parking secondary reduction worm (11). The mating surfaces of the parking secondary reduction worm wheel (12) and the planetary carrier (10) are respectively provided with worm wheel end face teeth (18) and planetary carrier end face teeth (19). The torque is transmitted by the contact and pressing of the worm wheel end face teeth (18) and the planetary carrier end face teeth (19) and is output by the planetary carrier output shaft (17). The service brake motor (1) and the parking brake motor (15) together output torque to the planetary carrier output shaft (17).

2. The electromechanical braking system based on a gear system for coupling driving and parking brakes according to claim 1, characterized in that: The first stage gear (2) of the triple gear system (40) is fixedly sleeved on the output shaft of the vehicle brake motor (1), the two ends of the second stage gear (3) are fixedly provided with second stage gear mounting bearings (4), and the third stage gear (6) is fixedly assembled on the sun gear input shaft (7) of the planetary gear system. One end of the sun gear input shaft (7) is provided with a third stage gear mounting bearing (5). The first stage gear (2), the second stage gear (3), and the third stage gear (6) mesh in sequence.

3. An electromechanical brake system based on coupling of service and parking brakes through a gear train as claimed in claim 1, wherein, The planetary gear system (50) includes a gear ring (8), a sun gear (21), planet gears (9), and a planet carrier (10). The sun gear (21) meshes with the planet gears (9). The planet gears (9) are fixedly mounted on the planet carrier (10) and mesh with the gear ring (8). The planet carrier (10) rotates to drive the output shaft (17) of the planet carrier, which is fixed coaxially at its end, to output braking torque. The third-stage gear (6) is provided with a gear groove (23), the inner diameter of which is larger than the outer diameter of the gear ring (8). The planetary gear system (50) is embedded in the cavity of the gear groove (23).

4. An electromechanical brake system based on coupling of service and parking brakes through a gear train as claimed in claim 1, wherein, The gear ring (8) is externally provided with a connecting key (20) which is assembled and fixed with the keyway on the gearbox housing.

5. An electromechanical brake system based on coupling of service and parking brakes through a gear train as claimed in claim 1, wherein: The transmission assembly includes a parking first-stage reduction worm gear (14), a parking first-stage reduction worm wheel (13), a parking second-stage reduction worm gear (11), a parking second-stage reduction worm wheel (12), and a parking second-stage reduction worm wheel mounting bearing (16). The parking first-stage reduction worm gear (14) is fixedly mounted on the parking brake motor (15). The parking first-stage reduction worm gear (14) meshes with the parking first-stage reduction worm wheel (13), and the parking second-stage reduction worm gear (11) meshes with the parking second-stage reduction worm wheel (12) in sequence. Both ends of the worm gear are fixed by the parking second-stage reduction worm gear fixing bearing (22).

6. An electromechanical brake system based on coupling of service and parking brakes through a gear train as claimed in claim 1, wherein: The third-stage gear (6) is mounted on the sun gear input shaft (7), while the parking second-stage reduction worm gear (12) is sleeved on the planetary carrier output shaft (17). The parking second-stage reduction worm gear mounting bearing (16) is mounted on the planetary carrier output shaft (17). The mating surfaces of the parking second-stage reduction worm gear (12) and the planetary carrier (10) are respectively provided with worm gear end face teeth (18) and planetary carrier end face teeth (19). The number of end face teeth is two or more and symmetrically arranged along the circumference. The worm gear end face teeth (18) and planetary carrier end face teeth (19) are used in pairs.

7. A gear train based electronic mechanical brake system for coupling service and parking brakes as claimed in claim 1 wherein: The first gear (2) is fixedly connected to the output shaft of the vehicle brake motor (1), the second gear (3) is fixedly connected to its mounting shaft, or is forged into one piece, and the mounting shaft is fitted with second gear mounting bearings (4) or bushings at both ends, the third gear (6) is fixedly connected to the sun gear input shaft (7), and the sun gear input shaft (7) is fitted with a third gear mounting bearing (5) at one end and connected to the sun gear (21) at the other end, and the sun gear (21) is integrally formed or press-fitted to the sun gear input shaft (7).

8. The electromechanical braking system based on a gear system for coupling driving and parking brakes according to claim 1, characterized in that: The parking brake secondary reduction worm gear (12) is connected to the planetary carrier output shaft (17) through a bearing or bushing. The end face teeth (18) of the parking brake secondary reduction worm gear (12) are in close contact with the end face teeth (19) of the planetary carrier (10). The working rotation angle of the planetary carrier (10) of the triple gear system (40) is less than 180 degrees.

9. An electromechanical brake system based on coupling of service and parking brakes through a gear train as claimed in claim 1, wherein: The parking secondary reduction worm gear (12) rotates coaxially with the planetary carrier output shaft (17). During parking braking, the torque is transmitted through the rotation and compression of the worm gear end face teeth (18) and the planetary carrier end face teeth (19). The working rotation angle of the parking secondary reduction worm gear (12) is less than 180 degrees.

10. A gear train based electronic mechanical brake system for coupling service and parking brakes as claimed in claim 5 wherein: The parking first-stage reduction worm gear (14) is fixedly connected to the output shaft of the parking brake motor (15). The parking first-stage reduction worm wheel (13) is fixedly mounted on the parking second-stage reduction worm gear (11) through a keyway or spline. Parking second-stage reduction worm gear fixed bearings (22) are provided at both ends of the parking second-stage reduction worm gear (11). The parking second-stage reduction worm gear (11) and the parking first-stage reduction worm wheel (13) are fixedly mounted or forged into one piece.

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