Push-rod-free EMB drum brake service braking executing structure and using method

Abstract

The invention belongs to the technical field of drum brake EMB service braking, and discloses a push-rod-free EMB drum brake service braking execution structure and a using method.The push-rod-free EMB drum brake service braking execution structure comprises an axle body, brake shoes are arranged at the wheel ends of the two sides of the axle body, the brake shoes are connected with a cam shaft, the cam shaft is connected with a speed reducing mechanism, and the output end of the speed reducing mechanism is connected with the cam shaft; the input end of the speed reducing mechanism is connected with a motor, the speed reducing mechanism comprises a gear transmission assembly which amplifies the output torque of the motor in a multi-stage mode, a bearing seat is fixedly installed on the axle body and tightly attached to the cam shaft, and the axis of an output shaft of the motor and the axis of the cam shaft are arranged in a coplanar mode. Through the coplanar layout of the motor, the speed reducing mechanism and the camshaft and the rigid connection design of a direct-drive power chain, a traditional push rod and lever transmission structure is abandoned, the performance of the braking system is comprehensively improved, the output shaft of the motor is directly connected with the speed reducing mechanism, the torque of the low-power motor is efficiently amplified, and a flexible transmission gap is eliminated; and the braking response speed and the energy transmission efficiency are obviously improved.

Description

Technical Field

[0001] The invention belongs to the technical field of EMB drum brake service brake, and in particular to a push rod-free EMB drum brake service brake execution structure and a use method. Background Art

[0002] As the automotive industry transforms towards intelligence and electrification, traditional pneumatic brake systems have been unable to meet the high standards of braking performance for advanced autonomous driving (L3+) and new energy vehicles due to delayed response, low control accuracy and insufficient reliability. Electro-Mechanical Brake (EMB) technology directly drives the wheel-end actuator through electrical signals, abandons the hydraulic / pneumatic transmission link, and has become the core braking solution for intelligent driving with its simplified structure, fast response, precise control and independent control. However, there is still a significant technical gap in the adaptability research of existing EMB technology in the field of pneumatic drum brakes for commercial vehicles, which restricts the technological upgrading process in this field.

[0003] Existing EMB solutions mostly rely on mechanical transmission chains to achieve the conversion of motor rotational motion to brake linear / rotational motion. For example, the disc brake EMB assembly of the Chinese patent application with publication number CN117104205A uses a ball screw transmission mechanism to replace the traditional hydraulic piston. Although it simplifies the fluid transmission link, if it is adapted to the drum brake to drive the camshaft to rotate, an additional push rod-rocker arm conversion mechanism needs to be added, resulting in a significant increase in structural complexity; at the same time, the high-precision assembly requirements of the ball screw and the maintenance costs under long-term service (such as lubrication and wear monitoring) further limit its applicability in commercial vehicle scenarios. The gear rack EMB solution proposed in the Chinese patent application with publication number CN114407857A directly converts the motor rotation into the push rod linear motion to drive the rocker arm through the gear rack. Although it retains the original camshaft structure of the commercial vehicle drum brake, it needs to occupy the brake air chamber installation space, and there is a multi-stage motion conversion of "rotation → linear → rotation", which has a large loss of transmission efficiency, and introduces additional failure risks due to redundant components such as gear rack pairs and push rod hinge points. The above scheme has the following problems: The motion chain is long. The initial conversion from motor rotation to linear motion is required through mechanical transmission (screw / gear rack), and then the secondary conversion to camshaft rotation is achieved through the push rod-rocker arm mechanism. The multi-stage transmission leads to superposition of energy loss and delayed dynamic response; poor spatial compatibility. The motor and transmission mechanism occupy the original brake chamber installation space, forcing the chassis structure to be reconstructed, hindering the low-cost upgrade of existing models; maintenance economy deteriorates: precision transmission components (such as ball screws and high-precision racks) are sensitive to assembly tolerances, and the high load and dusty working conditions of commercial vehicles accelerate wear, increasing the cost of the entire life cycle. Summary of the invention

[0004] The present invention provides a push rod-free EMB drum brake service brake execution structure and a method of use. By deeply analyzing the driving principle of the traditional pneumatic drum brake, the present invention reveals its essence: the brake shoe is opened to complete vehicle braking through the rotation of the camshaft. Based on the first principle analysis method, the present invention proposes a motor direct drive camshaft solution. This solution abandons the traditional multi-stage motion conversion mechanism and solves the problems of energy loss superposition, dynamic response delay and poor spatial compatibility caused by multi-stage transmission in the existing EMB brake mechanism.

[0005] To achieve the above object, the present invention provides the following technical solutions: The push rod-less EMB drum brake service brake execution structure includes a bridge body, brake shoes are arranged on the wheel ends on both sides of the bridge body, the brake shoes are connected to a camshaft, the camshaft is connected to a reduction mechanism, the output end of the reduction mechanism is connected to the camshaft, the input end of the reduction mechanism is connected to a motor, the reduction mechanism includes a gear transmission assembly for amplifying the output torque of the motor in multiple stages, a bearing seat is fixedly installed on the bridge body, the bearing seat is tightly fitted with the camshaft, and the output shaft axis of the motor and the axis of the camshaft are arranged in the same plane.

[0006] Preferably, the reduction mechanism is a first planetary gear reducer, which includes a first sun gear, which is connected to the motor output shaft through a first key, and the first sun gear is meshed with the three first planetary gears. A first reducer housing is provided on the outside of the first planetary gear reducer, and the first reducer housing is installed on a bearing seat. A first ring gear is installed on the inside of the first reducer housing, and the first ring gear is meshed with the three first planetary gears respectively. A first planetary gear bearing is provided in each of the first planetary gears, and a first planet carrier is connected to the inner surfaces of the three first planetary gear bearings, the input end of the first planet carrier is connected to the first planetary gear bearing, and the output end of the first planet carrier is connected to the camshaft.

[0007] Preferably, the first planetary gear bearing inner ring is transitionally fitted with the input end of the first planet carrier, and the first planetary gear bearing outer ring is interference fit with the inner hole of the first planetary gear.

[0008] Preferably, the reduction mechanism is a double-cavity two-stage gear reducer, which includes an input gear shaft, which is connected to the motor output shaft through a spline sleeve, and a reducer intermediate gear is meshed on the input gear shaft, and the reducer intermediate gear is connected to the reducer intermediate gear shaft through a key fit, the optical axis end of the reducer intermediate gear shaft is connected to the reducer intermediate gear, and the gear end of the reducer intermediate gear shaft is meshed with an output gear, and the output gear is connected to the camshaft through a second key.

[0009] Preferably, the camshaft is installed in a bearing seat via a double-row cylindrical roller bearing, and a first bearing seat end cover is provided on the outer side of the bearing seat.

[0010] Preferably, a second reducer housing is arranged outside the double-cavity two-stage gear reducer, and the reducer intermediate gear shaft and the input gear shaft are mounted on the second reducer housing through roller bearings.

[0011] Preferably, the reduction mechanism includes a second planetary gear reducer and a sector bevel gear set, the second planetary gear reducer includes a second sun gear, the output shaft of the motor is matched with the second sun gear through a key, the second sun gear is meshed with a second planetary gear, the second planetary gear is connected to a second planetary carrier through a second planetary gear bearing, the input end of the second planetary carrier is connected to the second planetary gear, the output end of the second planetary carrier is splined with an input bevel gear, the input bevel gear is meshed with an output bevel gear, and the output bevel gear is splined with a camshaft.

[0012] Preferably, a sector gear housing is provided outside the sector bevel gear set, the input bevel gear is mounted on the sector gear housing, and the input bevel gear and the sector gear housing are connected via a double-row angular contact bearing.

[0013] Preferably, the camshaft and the bearing seat are connected via two sets of double-row angular contact bearings.

[0014] A method for using a push rod-free EMB drum brake service brake execution structure, wherein a driver's brake pedal signal is transmitted to a motor, which first drives a camshaft to rotate, and then opens the brake shoe and enters a braking force following stage, wherein the load torque generated by braking acts on the motor to cause it to enter a stalled state, and the motor output braking torque is amplified through a reduction mechanism, and the amplified braking torque acts on the camshaft, and the braking torque of the camshaft continuously follows a target braking torque, and when the required braking force decreases, the motor current is reduced, the motor output torque is reduced and reversed at the same time, and the braking force of the brake is reduced, and when the required braking force is 0, the motor is controlled to reverse so that a gap is generated between the brake shoe and the brake wheel, thereby eliminating the braking force.

[0015] Compared with the prior art, the present invention has the following beneficial effects: the present invention provides a push rod-free EMB drum brake service brake execution structure, including a bridge body, brake shoes are arranged at the wheel ends on both sides of the bridge body, one end of a camshaft is connected to the brake shoe, the other end of the camshaft is connected to the output end of a reduction mechanism, the input end of the reduction mechanism is connected to a motor, the reduction mechanism includes a gear transmission assembly for multi-stage amplification of the motor output torque, a bearing seat is fixedly mounted on the bridge body, the bearing seat is tightly fitted to the camshaft and carries the rotational motion of the camshaft, the axis of the motor output shaft is coplanarly arranged with the axis of the camshaft, through the coplanar layout of the motor, the reduction mechanism and the camshaft and the rigid connection design of the direct-drive power chain, the traditional push rod and lever transmission structure is abandoned, and the comprehensive improvement of the braking system performance is achieved, the motor output shaft is directly connected to the reduction mechanism, the low-power motor torque is efficiently amplified, the flexible transmission gap is eliminated, and the braking response speed and energy transfer efficiency are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the movement of the existing conventional EMB drum brake mechanism (the left side is the initial state, and the right side is the braking state); Figure 2 This is a motion schematic diagram of a push rod-free motor direct-driven EMB brake mechanism of the present invention; Figure 3 This is a schematic diagram of the overall structure of Embodiment 1 proposed by the present invention; Figure 4 This is an axonometric diagram of the overall structure of Example 1 proposed by the present invention; Figure 5 A cross-sectional view of a planetary gear reducer in Embodiment 1 of the present invention; Figure 6 This is a cross-sectional view of the overall structure of Example 1 proposed by the present invention; Figure 7 This is a schematic diagram of the overall structure of Embodiment 2 proposed by the present invention; Figure 8 This is an axonometric diagram of the overall structure of Embodiment 2 proposed by the present invention; Fig. 9 This is a cross-sectional view of the overall structure of Example 2 proposed by the present invention; Fig.10 This is a schematic diagram of the bottom oil hole and installation position of the two-stage reducer of Example 2 proposed by the present invention; Fig.11 This is an axonometric view of the two-stage reducer housing of Example 2 proposed by the present invention; Fig.12 This is a schematic diagram of the overall structure of Embodiment 3 proposed by the present invention; Fig.13 This is an axonometric diagram of the overall structure of Embodiment 3 proposed by the present invention; Fig.14This is a cross-sectional view of the planetary reducer of the sector gear set motor of Example 3 proposed by the present invention; Fig.15 A cross-sectional view of a driving camshaft moving component of Embodiment 3 of the present invention; In the figure: 1-brake shoe, 2-camshaft, 3-first bearing seat, 301-threaded hole, 4-first planetary gear reducer, 401-first reducer housing, 402-first gear ring, 403-first planetary carrier, 404-first planetary gear bearing, 405-first planetary gear, 406-first sun gear, 407-retaining ring, 5-first motor, 501-first motor output shaft, 502-first key, 503-first mounting bolt, 6-bridge body, 7-second bearing seat, 7 01-first bearing seat end cover, 702-double-row cylindrical roller bearing, 8-double-cavity two-stage gear reducer, 801-end bearing, 802-spline sleeve, 803-roller bearing, 804-input gear shaft, 805-second reducer housing, 806-second reducer oil drain plug, 807-reducer intermediate gear, 808-reducer intermediate gear shaft, 809-first limit ring, 810-output gear, 811-second key, 812-connecting bolt, 9-second motor, 901-second motor output shaft, 902-second mounting bolt, 10-third bearing seat, 11-sector bevel gear set, 1101-second limiting ring, 1102-double-row angular contact bearing, 1103-input bevel gear, 1104-output bevel gear, 1105-sector gear housing, 1106-sector gear housing cover, 1107-end cover, 1108-pin shaft, 1109-second bearing seat end cover, 12-second planetary gear reducer, 1201-third reducer Housing, 1202-second planetary gear bearing, 1203-second planetary gear, 1204-second planetary carrier, 1205-second sun gear, 1206-second ring gear, 1207-reducer end cover, 13-third motor, 1301-third mounting bolt, 1302-third motor output shaft, 14-executor motor; 15-ball screw mechanism, 1501-screw; 1502-ball; 1503-nut push rod; 16-camshaft rocker arm; 17-reduction and torque-increasing mechanism. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0020] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0021] The existing conventional drum EMB brake structure and brake actuator are influenced by the traditional brake chamber and the disc EMB brake. Most of them use a ball screw mechanism to convert the motor's rotational motion into the linear motion of the nut push rod, and the rocker arm converts the linear motion into the rotational motion of the camshaft, thereby realizing the movement of the brake shoe and achieving vehicle braking. Figure 1 As shown, the existing conventional drum EMB brake mainly includes the following movements: the actuator motor 14 rotates; the ball screw mechanism 15 converts the actuator motor 14 rotational movement into the linear movement of the nut push rod 1503, specifically, the screw 1501 is connected to the output shaft of the actuator motor 14 to rotate, and drives the nut push rod 1503 to move linearly through the ball 1502; the camshaft rocker arm 16 converts the linear movement of the nut push rod 1503 into the rotational movement of the camshaft 2; the rotation of the camshaft 2 drives the cam movement, so that the brake shoe 1 opens to complete the vehicle braking. Due to the lengthy motion chain, the large number of motion conversions, the influence on the transmission efficiency, etc., the present invention provides a push rod-free motor direct-driven EMB brake mechanism, such as Figure 2 As shown, it mainly includes the following movements: the actuator motor 14 rotates; after being decelerated by the deceleration torque increasing mechanism 17, the rotational movement of the actuator motor 14 is transmitted to the camshaft 2; the rotation of the camshaft 2 drives the cam movement to open the brake shoe 1 to complete vehicle braking. The actuator motor 14 directly completes the driving of the camshaft 2, reducing the energy loss caused by the conversion of motion behavior and the complexity of the EMB brake mechanism.

[0022] Example 1 like Figure 2-6As shown, the present invention provides a push rod-free EMB drum brake service brake execution structure, including a bridge body 6, brake shoes 1 are arranged at the wheel ends on both sides of the bridge body 6, the brake shoes 1 are connected to the camshaft 2, the camshaft 2 is connected to a reduction mechanism, the output end of the reduction mechanism is connected to the camshaft 2, the input end of the reduction mechanism is connected to a motor, the reduction mechanism includes a gear transmission assembly for amplifying the output torque of the motor in multiple stages, a bearing seat is fixedly installed on the bridge body 6, the bearing seat is tightly fitted with the camshaft 2, and the output shaft axis of the motor and the axis of the camshaft 2 are arranged in the same plane.

[0023] The bearing seat adopts the first bearing seat 3, and the motor adopts the first motor 5; The first planetary gear reducer 4 includes a first sun gear 406, which is connected to the first motor output shaft 501 through a first key 502, and the first sun gear 406 is meshed with the three first planetary gears 405. A first reducer housing 401 is provided on the outside of the first planetary gear reducer 4, and the first reducer housing 401 is installed on the first bearing seat 3. A first ring gear 402 is installed on the inside of the first reducer housing 401, and the first ring gear 402 is respectively meshed with the three first planetary gears 405. A first planetary gear bearing 404 is provided in each of the first planetary gears 405, and the input end of the first planetary carrier 403 is connected to the inner surface of the three first planetary gear bearings 404, and the output end of the first planetary carrier 403 is connected to the camshaft 2.

[0024] The outer circle of the first gear ring 402 is provided with a rectangular groove, which cooperates with the rectangular boss inside the first reducer housing 401. The rectangular boss is used to limit and fix the first gear ring 402. The retaining ring 407 cooperates with the first bearing seat 3 to limit and fix the first gear ring 402 to the first reducer housing 401. The first motor 5 is connected to the first reducer housing 401 through the first mounting bolt 503.

[0025] The first reducer housing 401 and the first bearing seat 3 are positioned and fixed by means of a stop bolt installed on the threaded hole 301 , and the camshaft 2 cooperates with the bearing built into the first bearing seat 3 .

[0026] The inner ring of the first planetary gear bearing 404 is interference fit with the input end of the first planet carrier 403 , and the outer ring of the first planetary gear bearing 404 is clearance fit with the inner hole of the first planetary gear 405 .

[0027] A limiting groove is provided at the bottom of the first reducer housing 401, and there is a gap between the inner ring of the first planetary gear bearing 404 away from one end of the first planetary carrier 403 and the limiting groove; the first motor 5 is installed on the rectangular boss of the first reducer housing 401 by screws, and the first motor output shaft 501 and the first sun gear 406 are matched with the first key 502 to realize that the first motor 5 drives the first sun gear 406, and the first sun gear 406 drives the first planetary carrier 403 to drive the camshaft 2 to complete vehicle braking.

[0028] Working principle: The driver's brake pedal signal is transmitted to the first motor 5 through the VCU (Vehicle Control Unit). The first motor 5 first drives the camshaft 2 to rotate at a speed close to the no-load speed. After the brake shoe 1 is expanded, it enters the braking force following stage. At this time, the load torque generated by the brake acts on the first motor 5 to make it enter a locked state. The braking torque output by the first motor 5 is amplified by the first planetary gear reducer 4. The amplified braking torque acts on the camshaft 2 through the first planetary carrier 403. The braking torque of the camshaft 2 continues to follow the target braking torque. When the required braking force decreases, the current of the first motor 5 is reduced. The output torque of the first motor 5 decreases and the motor 5 reverses by a certain angle, and the braking force of the brake is reduced. When the required braking force is 0, the first motor 5 is controlled to reverse by a certain angle so that a certain gap is generated between the brake shoe 1 and the brake wheel, and the braking force is completely eliminated.

[0029] Example 2 like Figure 7-11 As shown, the present invention provides a push rod-free EMB drum brake service brake execution structure, including a bridge body 6, brake shoes 1 are arranged at the wheel ends on both sides of the bridge body 6, one end of a camshaft 2 is connected to the brake shoe 1, the other end of the camshaft 2 is connected to the output end of a reduction mechanism, the input end of the reduction mechanism is connected to a motor, the reduction mechanism includes a gear transmission assembly for amplifying the output torque of the motor in multiple stages, a bearing seat is fixedly installed on the bridge body 6, the bearing seat is tightly fitted with the camshaft 2 and bears the rotational movement of the camshaft 2, and the axis of the output shaft of the motor is arranged in the same plane as the axis of the camshaft 2.

[0030] The motor adopts a second motor 9, the second motor 9 includes a second motor output shaft 901, the bearing seat adopts a second bearing seat 7, the reduction mechanism is a double-cavity two-stage gear reducer 8, the double-cavity two-stage gear reducer 8 includes an end bearing 801, a spline sleeve 802, a roller bearing 803, an input gear shaft 804, a second reducer housing 805, a second reducer oil drain plug 806, a reducer intermediate gear 807, a reducer intermediate gear shaft 808, a first limit ring 809, an output gear 810, a second key 811 and a connecting bolt 812; the drum brake includes a second bearing seat 7, a first bearing seat end cover 701, a double-row cylindrical roller bearing 702, a camshaft 2 and a brake shoe 1.

[0031] The input gear shaft 804 is connected to the second motor output shaft 901 through a spline sleeve 802, and a reducer intermediate gear 807 is meshed on the input gear shaft 804. The reducer intermediate gear 807 is connected to the optical axis part of the reducer intermediate gear shaft 808 through a key fit, and the gear end of the reducer intermediate gear shaft 808 is meshed with an output gear 810, and the output gear 810 is connected to the camshaft 2 through a second key 811. First limiting rings 809 are installed on both sides of the reducer intermediate gear 807, one side of the first limiting ring 809 is fitted with the reducer intermediate gear 807, and the other side of the first limiting ring 809 is fitted with the inner ring side of the roller bearing 803, the input gear shaft 804 is meshed with the reducer intermediate gear 807, and the gear end of the input gear shaft 804 is connected to the second reducer housing 805 through the inner ring and the roller bearing 803 with a boss, and the second reducer housing 805 is composed of a housing and a housing cover. The second reducer housing 805 is connected and fixed by connecting bolts 812, wherein a second reducer oil drain plug 806 is provided at the bottom of the housing, a spline groove is processed on the shaft end of the input gear shaft 804, and the shaft end of the input gear shaft 804 is connected to the second reducer housing 805 through a roller bearing 803 without a boss; the second motor output shaft 901 is connected to the input gear shaft 804 through a spline sleeve 802, and the end faces of the spline sleeve 802 at both ends are connected to the second reducer housing 805 through end bearings 801, and a roller bearing 803 without a boss is installed at one end of the spline sleeve 802 close to the second motor output shaft 901, and the roller bearing 803 without a boss is connected to the second reducer housing 805, and the second motor 9 is installed on the second reducer housing 805 through the second mounting bolts 902, so that the second motor 9 finally drives the double-cavity two-stage gear reducer 8, and drives the camshaft 2 to complete vehicle braking.

[0032] like Fig. 9 and Fig.10As shown, a second reducer housing 805 is arranged on the outer side of the double-cavity two-stage gear reducer 8, the second motor 9 is fixed to the second reducer housing 805 by a second mounting bolt 902, the second motor output shaft 901 is connected to the reducer input gear shaft 804 by a spline sleeve 802, the input gear shaft 804 is meshed with the reducer intermediate gear 807, and the input gear shaft 804 is installed and matched with the second reducer housing 805 by a roller bearing 803; the reducer intermediate gear shaft 808 is installed and matched with the second reducer housing 805 by a roller bearing 803, the optical axis part of the reducer intermediate gear shaft 808 and the reducer intermediate gear 807 are motion-transmitted by key cooperation, and the gear end of the reducer intermediate gear shaft 808 is meshed with the output gear 810; the output gear 810 is matched with the camshaft 2 by a second key 811, the camshaft 2 is installed in the second bearing seat 7 by a double-row cylindrical roller bearing 702, and is positioned and assembled using the first bearing seat end cover 701.

[0033] Working principle: The driver's brake pedal signal is transmitted to the second motor 9 through the VCU. The second motor 9 first drives the camshaft 2 to rotate at a speed close to the no-load speed. After the brake shoe 1 is expanded, it enters the braking force following stage. At this time, the load torque generated by the brake acts on the second motor 9 to make it enter a stalled state. The braking torque output by the second motor 9 is amplified by the double-chamber two-stage gear reducer 8. The amplified braking torque acts on the camshaft 2 through the output gear 810. The braking torque of the camshaft 2 continues to follow the target braking torque. When the required braking force decreases, the current of the second motor 9 is reduced, the motor output torque is reduced and reversed by a certain angle at the same time, and the braking force of the brake is reduced. When the required braking force is 0, the second motor 9 is controlled to reverse by a certain angle so that a certain gap is generated between the brake shoe 1 and the brake wheel, and the braking force is completely eliminated.

[0034] Example 3 like Figure 12-15 As shown, the present invention provides a push rod-free EMB drum brake service brake execution structure, including a bridge body 6, brake shoes 1 are arranged at the wheel ends on both sides of the bridge body 6, one end of a camshaft 2 is connected to the brake shoe 1, the other end of the camshaft 2 is connected to the output end of a reduction mechanism, and the input end of the reduction mechanism is connected to a motor, the reduction mechanism includes a gear transmission assembly for amplifying the output torque of the motor in multiple stages, a bearing seat is fixedly installed on the bridge body 6, the bearing seat is tightly fitted with the camshaft 2 and carries the rotational movement of the camshaft 2, and the axis of the motor output shaft is arranged in the same plane as the axis of the camshaft 2.

[0035] The motor adopts the third motor 13, the third motor 13 includes a third motor output shaft 1302, and the bearing seat adopts the third bearing seat 10; The reduction mechanism includes a second planetary gear reducer 12 and a bevel sector gear set 11, the second planetary gear reducer 12 includes a third reducer housing 1201, a second planetary gear bearing 1202, a second planetary gear 1203, a second planetary carrier 1204, a second sun gear 1205, a second ring gear 1206 and a reducer end cover 1207, the bevel sector gear set includes a second limiting ring 1101, a double-row angular contact bearing 1102, an input bevel gear 1103, an output bevel gear 1104, a sector gear housing 1105, a sector gear housing cover 1106, an end cover 1107 and a pin 1108, and the drum brake includes a third bearing seat 10, a camshaft 2 and a brake shoe 1.

[0036] The third motor output shaft 1302 is matched with the second sun gear 1205 through a key, and the second sun gear 1205 is meshed with the second planetary gear 1203. The second planetary gear 1203 is connected to the input end of the second planetary carrier 1204 through the second planetary gear bearing 1202. The output end of the second planetary carrier 1204 is connected to the input bevel gear 1103 by a spline. The input bevel gear 1103 is meshed with the output bevel gear 1104, and the output bevel gear 1104 is matched with the camshaft 2 through a spline.

[0037] A sector gear housing 1105 is disposed outside the sector bevel gear set 11 . The third reducer housing 1201 is connected to the reducer end cover 1207 by bolts. The reducer end cover 1207 is mounted on the sector gear housing 1105 and connected by connecting bolts 812 .

[0038] The camshaft 2 and the third bearing seat 10 are connected via two sets of double-row angular contact bearings 1102 .

[0039] The third motor 13 is installed on the third reducer housing 1201 through the third mounting bolt 1301, the third motor output shaft 1302 and the second sun gear 1205 are matched through a key, the second sun gear 1205 is meshed with the second planetary gear 1203, the second planetary gear 1203 is installed on the input end of the second planetary carrier 1204 through the second planetary gear bearing 1202, the output end of the second planetary carrier 1204 is connected to the input bevel gear 1103 by a spline, the input bevel gear 1103 is connected to the sector gear housing 1105 through a double-row angular contact bearing 1102, the input bevel gear 1103 is positioned by a second limiting ring 1101, and the input The bevel gear 1103 is meshed with the output bevel gear 1104, the output bevel gear 1104 is splined with the camshaft 2, and the pin 1108 is used to position the camshaft 2 and the output bevel gear 1104, the end cover 1107 is used to seal the pin 1108, the camshaft 2 and the output bevel gear 1104, the camshaft 2 is connected to the third bearing seat 10 through two sets of double-row angular contact bearings 1102, the camshaft 2 and the third bearing seat 10 are sealed by the second bearing seat end cover 1109, the second planetary gear 1203 is meshed with the second ring gear 1206, and the second ring gear 1206 is installed on the third reducer housing 1201 through a limiting boss.

[0040] Working principle: The driver's brake pedal signal is transmitted to the third motor 13 through the VCU. The third motor 13 first drives the camshaft 2 to rotate at a speed close to the no-load speed. After the brake shoe 1 is expanded, it enters the braking force following stage. At this time, the load torque generated by the brake acts on the execution motor to make it enter a stalled state. The third motor 13 outputs a braking torque which is amplified by the second planetary gear reducer 12. The amplified braking torque is transmitted to the input bevel gear 1103. The output bevel gear 1104 converts the rotational motion of the input bevel gear 1103 into the translational motion of the camshaft 2. The braking torque of the camshaft 2 continues to follow the target braking torque. When the required braking force decreases, the current of the third motor 13 is reduced, the motor output torque is reduced and reversed by a certain angle at the same time, and the braking force of the brake is reduced. When the required braking force is 0, the third motor 13 is controlled to reverse by a certain angle so that a certain gap is generated between the brake shoe 1 and the brake wheel, thereby completely eliminating the braking force.

[0041] Although the embodiments of the present invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments and application fields, and the above-mentioned specific embodiments are only illustrative and instructive, rather than restrictive. Under the guidance of the specification, a person skilled in the art can make many forms without departing from the scope of protection of the claims of the present invention, all of which belong to the scope of protection of the present invention.

Claims

1. The service brake actuation structure of the EMB drum brake without a push rod is characterized by: The invention comprises a bridge body (6), wherein the wheel ends on both sides of the bridge body (6) are provided with brake shoes (1), the brake shoes (1) are connected to a camshaft (2), the camshaft (2) is connected to a reduction mechanism, the output end of the reduction mechanism is connected to the camshaft (2), the input end of the reduction mechanism is connected to a motor, the reduction mechanism comprises a gear transmission assembly for amplifying the output torque of the motor in multiple stages, a bearing seat is fixedly mounted on the bridge body (6), the bearing seat is tightly fitted with the camshaft (2), and the axis of the output shaft of the motor is arranged in the same plane as the axis of the camshaft (2).

2. The push rod-less EMB drum brake service brake actuation structure according to claim 1, characterized in that: The reduction mechanism is a first planetary gear reducer (4), the first planetary gear reducer (4) comprising a first sun gear (406), the first sun gear (406) being connected to the output shaft of the motor via a first key (502), the first sun gear (406) being meshed with three first planetary gears (405), a first reducer housing (401) being arranged on the outside of the first planetary gear reducer (4), the first reducer housing (401) being mounted on a bearing seat, a first gear ring (402) being mounted on the inside of the first reducer housing (401), the first gear ring (402) being meshed with the three first planetary gears (405) respectively, a first planetary gear bearing (404) being arranged in each of the first planetary gears (405), the inner surfaces of the three first planetary gear bearings (404) being connected to first planet carriers (403), the input end of the first planet carrier (403) being connected to the first planetary gear bearing (404), and the output end of the first planet carrier (403) being connected to the camshaft (2).

3. The push rod-less EMB drum brake service brake actuation structure according to claim 2, characterized in that: The inner ring of the first planetary gear bearing (404) is transitionally fitted with the input end of the first planet carrier (403), and the outer ring of the first planetary gear bearing (404) is interference fitted with the inner hole of the first planetary gear (405).

4. The push rod-less EMB drum brake service brake actuation structure according to claim 1, characterized in that: The reduction mechanism is a double-cavity two-stage gear reducer (8), comprising an input gear shaft (804), the input gear shaft (804) being connected to an output shaft of a motor via a spline sleeve (802), a reducer intermediate gear (807) being meshed on the input gear shaft (804), the reducer intermediate gear (807) being connected to a reducer intermediate gear shaft (808) via a key, the optical axis end of the reducer intermediate gear shaft (808) being connected to the reducer intermediate gear (807), the gear end of the reducer intermediate gear shaft (808) being meshed with an output gear (810), and the output gear (810) being connected to a camshaft (2) via a second key (811).

5. The push rod-less EMB drum brake service brake actuation structure according to claim 4, characterized in that: The camshaft (2) is installed in a bearing seat via a double-row cylindrical roller bearing (702), and a first bearing seat end cover (701) is provided on the outer side of the bearing seat.

6. The push rod-less EMB drum brake service brake actuation structure according to claim 4, characterized in that: A second reducer housing (805) is provided on the outside of the double-cavity two-stage gear reducer (8), and the reducer intermediate gear shaft (808) and the input gear shaft (804) are mounted on the second reducer housing (805) via roller bearings (803).

7. The push rod-less EMB drum brake service brake actuation structure according to claim 1, characterized in that: The reduction mechanism comprises a second planetary gear reducer (12) and a sector bevel gear set (11); the second planetary gear reducer (12) comprises a second sun gear (1205); the output shaft of the motor is mated with the second sun gear (1205) via a key; the second sun gear (1205) is meshed with a second planetary gear (1203); the second planetary gear (1203) is connected to a second planet carrier (1204) via a second planetary gear bearing (1202); the input end of the second planet carrier (1204) is connected to the second planetary gear (1203); the output end of the second planet carrier (1204) is spline-connected to an input bevel gear (1103); the input bevel gear (1103) is meshed with an output bevel gear (1104); and the output bevel gear (1104) is mated with a camshaft (2) via a spline.

8. The push rod-less EMB drum brake service brake actuation structure according to claim 7, characterized in that: A sector gear housing (1105) is provided on the outside of the sector bevel gear set (11), the input bevel gear (1103) is mounted on the sector gear housing (1105), and the input bevel gear (1103) and the sector gear housing (1105) are connected via a double-row angular contact bearing (1102).

9. The push rod-less EMB drum brake service brake actuation structure according to claim 8, characterized in that: The camshaft (2) and the bearing seat are connected via two sets of double-row angular contact bearings (1102).

10. A method for using a push rod-less EMB drum brake service brake actuation structure, based on the push rod-less EMB drum brake service brake actuation structure according to any one of claims 1 to 9, characterized in that: The driver's brake pedal signal is transmitted to the motor, which first drives the camshaft (2) to rotate, and then opens the brake shoe (1) to enter the braking force following stage. The load torque generated by the brake acts on the motor to make it enter a stalled state. The motor outputs the braking torque, which is amplified by the reduction mechanism. The amplified braking torque acts on the camshaft (2). The braking torque of the camshaft (2) continues to follow the target braking torque. When the required braking force decreases, the motor current is reduced, the motor output torque is reduced and reversed at the same time, and the brake force is reduced. When the required braking force is 0, the motor is controlled to reverse so that a gap is generated between the brake shoe (1) and the brake wheel, thereby eliminating the braking force.

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