Compact electronic mechanical brake

Abstract

The invention relates to the technical field of brake-by-wire, in particular to a compact electronic mechanical brake which comprises a caliper body assembly, a support assembly and an MGU assembly and is characterized in that the MGU assembly comprises a motor assembly and a transmission mechanism; the transmission mechanism comprises an input gear part connected with the driving input end of the motor assembly and an output gear part connected with the braking output end. The input gear part and the output gear part are in meshing transmission through an idle gear, and the axis of the idle gear is offset relative to the connecting line where the axis of the input gear part and the axis of the output gear part are located, so that the distance between the axis of the input gear part and the axis of the output gear part is reduced. The compact electronic mechanical brake aims to solve the problems that in the prior art, due to the fact that a parking function is integrated, a brake is complex in structure, large in axial size, large in size and difficult to adapt to the compact arrangement space of a wheel edge.

Description

Technical Field

[0001] This invention relates to the field of brake-by-wire technology, and in particular to a compact electromechanical brake. Background Technology

[0002] With the widespread adoption of brake-by-wire systems in new energy vehicles, electromechanical brakes (EMBs) integrating parking functions have become the mainstream in the industry. However, existing EMB products, after integrating the parking mechanism, generally face problems of complex structure and numerous parts, typically requiring various bearings and bushings. Furthermore, traditional layouts, limited by drivetrain design, often occupy a long axial space, resulting in a large overall brake volume that is difficult to adapt to increasingly limited wheel-side space. Therefore, there is an urgent need to design a compact EMB to solve the problems of complex structure, large axial dimensions, and bulky size in existing technologies due to integrated parking functions, making them unsuitable for compact wheel-side arrangements. Summary of the Invention

[0003] The purpose of this invention is to provide a compact electromechanical brake to solve the problems of complex structure, large axial dimension and bulky size of existing brakes due to the integration of parking functions, which makes it difficult to adapt to the compact arrangement space at the wheel end.

[0004] The technical solution of this invention is: a compact electromechanical brake, comprising: a clamp assembly, a bracket assembly, and an MGU assembly, characterized in that: The MGU assembly includes a motor assembly and a transmission mechanism; The transmission mechanism includes an input gear section connected to the drive input end of the motor assembly, and an output gear section connected to the brake output end; The input gear section and the output gear section are driven by an idler gear. The axis of the idler gear is offset relative to the line connecting the axis of the input gear section and the axis of the output gear section, so as to reduce the distance between the axis of the input gear section and the axis of the output gear section, thereby reducing the radial dimension of the MGU assembly as a whole. The idler wheel is axially confined within an axial mounting space inside the motor assembly; An idler wheel shim is provided on one side of the idler wheel. By selecting idler wheel shims of different thicknesses, the axial working clearance of the idler wheel can be adjusted, thereby controlling its axial movement within a preset range.

[0005] Preferably, the output gear section includes a set of mating gears that meshes with the idler gear. The set of mating gears includes a first gear and a second gear that are coaxially arranged and fixed to each other. A first central shaft passes through the center of the first gear and the second gear. A first stepped groove for storing lubricating grease is formed on the axial surface of the first central shaft.

[0006] Preferably, the output gear section further includes a planetary gear set that meshes with the mating gear set. The planetary gear set includes a planetary gear cage, and the planetary gear cage has a plurality of second central shafts distributed circumferentially. Each second central shaft has a second stepped groove for storing lubricating grease on its shaft surface, and a third gear is sleeved on each second central shaft.

[0007] Preferably, the depths of the first stepped groove and the second stepped groove need to satisfy 0.01a≤d≤0.05a, and the distances from the sidewalls of the first stepped groove and the second stepped groove to the end face of the corresponding mating gear need to satisfy 0.15a≤l≤0.35a, where a is the thickness of the corresponding mating gear; For a central axis with multiple stepped grooves, the axial distance p between two adjacent stepped grooves must satisfy 3d≤p≤10d.

[0008] Preferably, the end face of the third gear near the planetary gear cage is provided with a friction-reducing boss, and the second central shaft is provided with a retaining ring groove, in which a retaining ring is installed. The retaining ring and the friction-reducing boss together restrict the axial displacement of the third gear.

[0009] Preferably, the input gear section includes a motor gear and a ratchet connected to the output end of the motor, the motor gear and the ratchet are fixedly connected, wherein the motor gear meshes with the idler gear for transmission, and the ratchet is connected to the parking mechanism.

[0010] Preferably, the parking mechanism includes a pawl disposed on one side of the ratchet and an electromagnet for driving the pawl.

[0011] Preferably, the motor assembly further includes a lower housing, on which a gear ring is interference-fitted at a position corresponding to the output gear section, and the output gear section meshes with the gear ring.

[0012] Preferably, the outer circumferential surface of the gear ring is provided with an anti-rotation structure, which is embedded in the inner wall of the lower housing during interference fitting. The end of the lower housing has a riveting part formed by plastic deformation, which engages with the limiting structure on the gear ring.

[0013] Preferably, the input gear section and the output gear section are provided with a retainer on the side away from the motor assembly in the axial direction, and the retainer and the housing of the motor assembly together form the axial mounting space.

[0014] Compared with the prior art, the advantages of the present invention are: (1) By adopting an idler gear offset design and offsetting its axis relative to the line connecting the input and output gear shafts, the radial dimension of the MGU assembly is effectively reduced, making the overall structure of the brake more compact and improving its adaptability and versatility in the limited space of the wheel side.

[0015] (2) By opening stepped grooves on the shaft surfaces of the first and second central shafts supporting the gears to store lubricating grease, lubrication is provided for the gears and shafts, replacing the bearing bushings required in the traditional design. While reducing frictional loss, the bushing parts and the radial installation space they occupy are directly eliminated, thereby further reducing the overall size of the transmission mechanism. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the overall structure of the electromechanical brake described in this invention; Figure 2 This is a schematic diagram of the internal structure of the MGU assembly described in this invention; Figure 3 This is an exploded view of the internal structure of the MGU assembly described in this invention; Figure 4 This is an exploded view of the planetary gear set described in this invention; Figure 5 This is an exploded view of the motor assembly described in this invention; Figure 6 For the present invention Figure 2 Enlarged view of region A in the middle; Figure 7 This is a cross-sectional view of the planetary gear retaining ring assembly part described in this invention; Figure 8 For the present invention Figure 3 Enlarged view of region B in the middle; The components are as follows: 1. Clamp body assembly; 2. Bracket assembly; 3. MGU assembly; 31. Motor assembly; 311. Lower housing; 312. Motor gear; 313. Ratchet; 314. Gear ring; 32. Pawl; 33. Electromagnet; 34. Idler wheel; 35. Idler wheel washer; 36. Cage; 361. First central shaft; 3611. First stepped groove; 37. Mating gear set; 371. First gear; 372. Second gear; 38. Planetary gear set; 381. Snap ring; 3811. Anti-friction boss; 382. Third gear; 383. Planetary gear cage; 384. Second central shaft; 3841. Second stepped groove. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to specific embodiments: like Figures 1 to 8 As shown, a compact electromechanical brake includes a caliper assembly 1, a bracket assembly 2, and an MGU assembly 3. The caliper assembly 1 is connected to the bracket assembly 2 for overall installation and load support of the brake. The MGU assembly 3 serves as the power source and transmission core, including a motor assembly 31 and a transmission mechanism. The transmission mechanism includes an input gear connected to the drive input end of the motor assembly 31 and an output gear connected to the brake output end.

[0018] Specifically, such as Figure 2 and Figure 6 As shown, the input gear section and the output gear section are connected by an idler gear 34. To accommodate the limited space on the wheel rim and achieve a compact structure, the idler gear 34 is offset, meaning its axis is offset relative to the line connecting the axes of the input and output gear sections. This offset layout reduces the distance between the axes of the input and output gear sections, thereby reducing the overall radial dimension of the MGU assembly 3 and making the structure more compact.

[0019] like Figure 2 and Figure 3 As shown, the output gear section includes a set of mating gears 37 meshing with an idler gear 34, and a planetary gear set 38 meshing with the set of mating gears 37. The set of mating gears 37 includes a first gear 371 and a second gear 372 coaxially arranged and fixed to each other, wherein the first gear 371 meshes with the idler gear 34, and the second gear 372 is used for subsequent driving. A first central shaft 361 is passed through the center of the first gear 371 and the second gear 372, and a first stepped groove 3611 for storing lubricating grease is formed on the axial surface of the first central shaft 361.

[0020] In a preferred embodiment, since the first central shaft 361 passes through both the first gear 371 and the second gear 372, and has a relatively long axial length, multiple equidistant first stepped grooves 3611 are provided on the first central shaft 361 along the axial direction to ensure uniform distribution of lubricating grease throughout the entire mating length and avoid lubrication dead zones. This multi-groove design can form a continuous lubricating grease storage band, effectively compensating for grease loss during long shaft mating, ensuring that the gear and shaft maintain a good oil film throughout the entire stroke contact range, thereby reducing wear and improving transmission efficiency.

[0021] like Figure 3 and Figure 4 As shown, the planetary gear set 38 includes a planetary gear cage 383, and a plurality of second central shafts 384 are circumferentially distributed on the planetary gear cage 383. Each second central shaft 384 has a second stepped groove 3841 for storing lubricating grease on its shaft surface, and a third gear 382 is sleeved on each second central shaft 384.

[0022] like Figure 7 As shown, the depths of the first stepped groove 3611 and the second stepped groove 3841 must satisfy 0.01a≤d≤0.05a, and the distances from the sidewalls of the first stepped groove 3611 and the second stepped groove 3841 to the end faces of the corresponding mating gears must satisfy 0.15a≤l≤0.35a, where a is the thickness of the corresponding mating gear. The above are preferred parameters for this embodiment. The limited groove depth d design ensures sufficient lubricating grease storage within the groove to meet long-term replenishment needs, while avoiding excessive weakening of the central shaft's structural strength and rigidity due to excessive groove depth. The limited distance l between the sidewalls of the stepped groove and the end faces of the corresponding mating gears ensures that the stepped grooves avoid the tooth root region where the gear bears the maximum load, preventing shaft breakage or deformation.

[0023] like Figure 7 and Figure 8 As shown, for a central shaft with multiple stepped grooves, the axial distance p between two adjacent stepped grooves must satisfy 3d ≤ p ≤ 10d. By controlling the groove distance p within the range of 3 to 10 times the groove depth d, it is possible to avoid a significant reduction in shaft strength due to excessively close groove distances, and to prevent lubrication interruption due to excessively large groove distances. This ensures that the grease in each groove can relay to cover the entire mating surface, thereby achieving the best lubrication effect.

[0024] The first stepped groove 3611 and the second stepped groove 3841 provide a different lubrication and support method than traditional bearing bushings. Compared to the conventional solution using bushings, this solution utilizes the lubricating grease stored in the stepped grooves to form an oil film between the mating surfaces of the shaft and the gear hole, achieving a lubrication mode instead of the traditional solid bushing contact. This structure not only eliminates the bushing component, reducing material costs and assembly processes, but also effectively reduces the radial dimensions of internal parts by eliminating the wall thickness occupied by the bushing, providing space for further miniaturization of the mechanism.

[0025] like Figure 7 As shown, in order to further optimize the operating performance of the planetary gear set 38, the end face of the third gear 382 near the planetary gear cage 383 is provided with a friction-reducing boss 3811, and the second central shaft 384 is provided with a retaining ring groove. The retaining ring 381 is installed in the retaining ring groove. The retaining ring 381 and the friction-reducing boss 3811 together restrict the axial displacement of the third gear 382 and prevent it from moving axially.

[0026] The input gear section includes a motor gear 312 and a ratchet 313 connected to the motor output end. The motor gear 312 and ratchet 313 are fixedly connected (e.g., via splines, welding, or other connection methods). The motor gear 312 meshes with an idler gear 34 for transmission, and the ratchet 313 is connected to the parking mechanism. The parking mechanism includes a pawl 32 located on one side of the ratchet 313 and an electromagnet 33 that drives the pawl 32. When parking is required, the electromagnet 33 actuates, driving the pawl 32 to engage with the ratchet 313, thereby locking the drive shaft and achieving the parking brake function.

[0027] The motor assembly 31 also includes a lower housing 311. A gear ring 314 is interference-fitted onto the lower housing 311 at a position corresponding to the output gear section. The output gear section (specifically, a planetary gear set 38) meshes with the gear ring 314. To prevent circumferential rotation and axial disengagement of the gear ring 314 on the lower housing 311, an anti-rotation structure is provided on the outer circumferential surface of the gear ring 314. The anti-rotation structure is embedded into the inner wall of the lower housing 311 during interference fitting. The end of the lower housing 311 has a riveting part formed by plastic deformation, which engages with a limiting structure on the gear ring 314.

[0028] As a preferred embodiment, the anti-rotation structure can specifically be an anti-rotation structure in the shape of an involute spline, a triangular pointed corner, a trapezoidal spline, or knurling. During the interference fit process, the flower-shaped tooth tips will be compressed and undergo plastic deformation or directly embedded into the inner wall of the lower housing 311; wherein, the lower housing 311 can be designed as a smooth hole at this mating point to utilize the material's own containment, or it can be designed as a contoured hole that matches the flower pattern on the outer wall of the gear ring 314 to increase the contact area. This mating method can firmly clamp the gear ring 314 into the lower housing 311, thereby effectively overcoming the circumferential torque on the gear ring 314 by utilizing the meshing resistance, ensuring the circumferential anti-rotation reliability of the gear ring 314; after the gear ring 314 is pressed into place, a riveting action is performed at the end of the lower housing 311 (for plastic housings, a hot riveting method can be used), causing the end of the housing to undergo local plastic deformation and roll inward. These deformed riveted parts form a tight snap-fit ​​with one or more stepped structures pre-installed at the end of the gear ring 314, and limit the axial displacement of the gear ring 314 through mechanical interference, thereby achieving axial anti-detachment of the gear ring 314 on the lower housing 311.

[0029] The input gear section and the output gear section are provided with a retainer 36 on the side away from the motor assembly 31 in the axial direction. The retainer 36 and the housing of the motor assembly 31 together form an axial mounting space located inside the motor assembly 31. The idler gear 34 is axially confined within the axial mounting space.

[0030] like Figure 3 As shown, in terms of assembly process, in order to reduce the complexity of parts development while ensuring gear meshing accuracy, an idler wheel shim 35 is provided on one side of the idler wheel 34. By selecting idler wheel shims 35 of different thicknesses, the axial working clearance of the idler wheel 34 can be adjusted, thereby controlling its axial movement within a preset range. To improve the efficiency of the gear set, a bearing (needle roller bearing or sliding bearing) is fitted in the idler wheel 34 to reduce friction loss. The inner diameter of the bearing engages with the pin on the motor assembly 31 to maintain good radial constraint on the gear.

[0031] Working principle: When service braking is required, the motor of the motor assembly 31 starts, driving the motor gear 312 to rotate. The motor gear 312 transmits power to the mating gear set 37 through the idler gear 34 it meshes with. The first gear 371 and the second gear 372 of the mating gear set 37 rotate synchronously, thereby driving the planetary gear set 38 to move. During the transmission process, the offset design of the idler gear 34 effectively reduces the radial space. In addition, the stepped grooves (3611, 3841) on the first central shaft 361 and the second central shaft 384 continuously supply lubricating grease to the contact surface between the gears and shafts, replacing the traditional bushing friction with oil film lubrication, reducing costs and further saving space. Finally, the torque output by the planetary gear set 38 drives the brake actuator to generate clamping force, realizing braking.

[0032] When the parking brake needs to be applied, the electromagnet 33 is energized, driving the pawl 32 to move and engage with the teeth of the ratchet 313, which rotates synchronously with the motor gear 312. Since the ratchet 313 is locked by the pawl 32, gear transmission cannot continue, thus achieving mechanical locking at the output end.

[0033] The above embodiments are merely illustrative of the technical concept and features of the present invention, intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and should not be construed as limiting the scope of protection of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and thus all changes falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention.

Claims

1. A compact electromechanical brake, comprising a caliper assembly (1), a bracket assembly (2), and an MGU assembly (3), characterized in that: The MGU assembly (3) includes a motor assembly (31) and a transmission mechanism; The transmission mechanism includes an input gear section connected to the drive input end of the motor assembly (31) and an output gear section connected to the brake output end; The input gear section and the output gear section are meshed and driven by an idler wheel (34). The axis of the idler wheel (34) is offset relative to the line connecting the axis of the input gear section and the axis of the output gear section, so as to reduce the distance between the axis of the input gear section and the axis of the output gear section, thereby reducing the overall radial dimension of the MGU assembly (3). The idler wheel (34) is axially confined within an axial mounting space inside the motor assembly (31); The idler wheel (34) is provided with an idler wheel shim (35) on one side. By selecting idler wheel shims (35) of different thicknesses, the axial working clearance of the idler wheel (34) can be adjusted, thereby controlling its axial movement within a preset range.

2. A compact electromechanical brake according to claim 1, characterized in that: The output gear section includes a set of mating gears (37) that meshes with the idler gear (34). The set of mating gears (37) includes a first gear (371) and a second gear (372) that are coaxially arranged and fixed to each other. A first central shaft (361) is provided through the center of the first gear (371) and the second gear (372). At least one first stepped groove (3611) for storing lubricating grease is provided on the axial surface of the first central shaft (361) along the axial direction.

3. A compact electromechanical brake according to claim 2, characterized in that: The output gear section also includes a planetary gear set (38) that meshes with the mating gear set (37). The planetary gear set (38) includes a planetary gear cage (383). The planetary gear cage (383) has a plurality of second central shafts (384) distributed circumferentially. Each second central shaft (384) has at least one second stepped groove (3841) for storing lubricating grease opened axially on its axial surface. Each second central shaft (384) is fitted with a third gear (382).

4. A compact electromechanical brake according to claim 3, characterized in that: The depths of the first stepped groove (3611) and the second stepped groove (3841) must satisfy 0.01a≤d≤0.05a, and the distances from the sidewalls of the first stepped groove (3611) and the second stepped groove (3841) to the end face of the corresponding mating gear must satisfy 0.15a≤l≤0.35a, where a is the thickness of the corresponding mating gear; For a central axis with multiple stepped grooves, the axial distance p between two adjacent stepped grooves must satisfy 3d≤p≤10d.

5. A compact electromechanical brake according to claim 3, characterized in that: The third gear (382) has a friction-reducing boss (3811) on the end face near the planetary gear cage (383). The second central shaft (384) has a retaining ring groove, and the retaining ring (381) is installed in the retaining ring groove. The retaining ring (381) and the friction-reducing boss (3811) together restrict the axial displacement of the third gear (382).

6. A compact electromechanical brake according to claim 1, characterized in that: The input gear section includes a motor gear (312) and a ratchet (313) connected to the output end of the motor. The motor gear (312) and the ratchet (313) are fixedly connected. The motor gear (312) meshes with the idler wheel (34) for transmission. The ratchet (313) is connected to the parking mechanism.

7. A compact electromechanical brake according to claim 6, characterized in that: The parking mechanism includes a pawl (32) disposed on one side of the ratchet (313) and an electromagnet (33) for driving the pawl (32).

8. A compact electromechanical brake according to claim 7, characterized in that: The motor assembly (31) also includes a lower housing (311), on which a gear ring (314) is interference-fitted at a position corresponding to the output gear section, and the output gear section meshes with the gear ring (314).

9. A compact electromechanical brake according to claim 8, characterized in that: The outer circumferential surface of the gear ring (314) is provided with an anti-rotation structure. The anti-rotation structure is embedded in the inner wall of the lower housing (311) during interference fitting. The end of the lower housing (311) has a riveting part formed by plastic deformation. The riveting part is engaged with the limiting structure on the gear ring (314).

10. A compact electromechanical brake according to claim 1, characterized in that: The input gear section and the output gear section are provided with a retainer (36) on the side away from the motor assembly (31) in the axial direction. The retainer (36) and the housing of the motor assembly (31) together form the axial mounting space.

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