A transmission mechanism for an electronic brake assist system

Abstract

The utility model provides a transmission mechanism for electronic brake auxiliary system, including shell and the inside shell of setting push force subassembly, ball screw pair, transmission subassembly and power component in proper order, the output shaft of power component adopts hollow shaft structure, the first end of ball screw is connected with push force subassembly, its second end coaxially extends into the installation cavity of output shaft, transmission subassembly adopts planetary gear system, and the motor power of power component is transmitted to the nut, drives the axial movement of ball screw, and push force subassembly is connected through the guiding anti -rotation structure with shell, only can axial movement, and its end portion is equipped with the limiting block of locating block and nut end portion cooperation, constitutes the rotation stop, effectively avoided the ball jam and eliminated huge axial impact force. The utility model structure is compact, and the braking response is quick, and the operation is stable and reliable, is applicable to commercial vehicle electronic mechanical braking system.

Description

Technical Field

[0001] This utility model relates to the field of mechanical semi-automation technology, specifically to a transmission mechanism for an electronic brake assist system. Background Technology

[0002] Traditional vehicle braking systems, especially those for medium and heavy-duty commercial vehicles, commonly employ pneumatic braking systems. These systems typically include an air compressor, air tank, foot valve, brake chambers, and wheel brakes (drum or disc brakes). However, these traditional systems suffer from inherent drawbacks such as slow response times exceeding 600 milliseconds, low control precision, unreliable performance, high operating noise, complex structure, and large space requirements. With the widespread application of electronic stability control systems such as anti-lock braking systems (ABS) and electronic braking systems (EBS), increased system complexity and costs have driven the industry towards electromechanical braking (EMB). EMB brakes, with their advantages of simple structure, rapid response, precise control, and high safety, have become a crucial direction for future braking technology development.

[0003] Despite the significant advantages of electromechanical brakes, existing implementations still have many shortcomings. For example, Chinese patent CN119641825A discloses an electromechanical brake for commercial vehicles. This brake includes a brake travel chamber, a force transmission module, and a motor drive module connected in sequence. The force transmission module transmits the driving force from the motor drive module to the brake travel chamber to drive the brake caliper connected to the brake travel chamber. The brake transmission push rod included in the force transmission module and the brake actuation push plate of the brake travel chamber are designed with an arc surface fit to generate a maximum swing angle of ±4°. Structurally, this prior art has a separately arranged lead screw, and the transmission module and motor are all connected in series along the same axis, resulting in a very long axial length of the brake and underutilization of radial space, which is wasteful and detrimental to the brake's overall vehicle layout. Specifically, existing vehicle chassis have many components installed in limited space; therefore, each component requires high performance and small size. Brakes, in particular, are mounted on wheel hubs, which are already quite small. Furthermore, the space around the wheel hub is further limited by the installation of steering and drive system components, making the space even more confined. Therefore, the structural design requirements for brakes are quite demanding. Existing technologies have very long axial structures, increasing the difficulty of overall vehicle layout and even making installation impossible.

[0004] Furthermore, the excessive axial length of the brake, with its center of gravity far from the fixed point, generates significant swaying moments during vehicle operation, especially on bumpy roads, negatively impacting the reliability and stability of the brake and other components. Additionally, the brake uses an end-face stop structure to limit the axial movement of the ball screw. This stopping method has the following drawbacks: First, the ball screw's helix angle is extremely small. At the moment of stopping, the load suddenly increases. The inertial torque combined with the motor torque, even if the total torque is not very large, still generates a significant axial force. This force acts on the axial components, placing extremely stringent design requirements on the components bearing this axial force, making design difficult. Second, the simultaneous rotation between the ball screw and nut, along with the end-face stop locking, increases the risk of the ball screw jamming, resulting in low overall brake stability.

[0005] Therefore, in order to address the shortcomings of existing electromechanical braking in terms of structural layout, space utilization, braking reliability, and response performance, it is necessary to optimize the design of the existing transmission mechanism. By optimizing the layout, the braking structure, and the transmission ratio, the vehicle's assembly adaptability, operational stability, and braking response rate can be improved. Utility Model Content

[0006] The purpose of this utility model is to provide a transmission mechanism for an electronic brake assist system. Through innovative spatial layout and stop structure design, it effectively overcomes the technical defects of existing electromechanical brakes, such as long axial dimensions, unreasonable space utilization, poor stop reliability, and easy generation of impact loads, while ensuring braking performance. It has comprehensive advantages such as compact structure, fast braking response, stable and reliable operation, and easy assembly and maintenance, and is suitable for promotion and application in electronic brake assist systems of commercial vehicles.

[0007] To achieve the above objectives, the present invention proposes the following technical solution:

[0008] A transmission mechanism for an electronic brake assist system includes a housing, wherein a thrust assembly, a ball screw pair, a transmission assembly, and a power assembly are sequentially arranged from a first end to a second end within the housing. The power assembly includes a motor and an output shaft, wherein the output shaft is a hollow shaft coaxially disposed at the output end of the motor, and a cylindrical mounting cavity is formed inside it.

[0009] The ball screw assembly includes a ball screw and a nut that is threaded to it. The first end of the ball screw is connected to the thrust assembly, and the second end of the ball screw extends coaxially into the mounting cavity.

[0010] The nut is axially fixed and rotates only circumferentially, while the ball screw is circumferentially fixed and moves only linearly axially.

[0011] As a preferred technical solution of this utility model, the transmission component includes a sun gear, a planetary gear, and a gear ring;

[0012] The sun gear is fixedly mounted on the outside of the output shaft;

[0013] The planetary gear is mounted on the inner wall of the housing via a planetary shaft and meshes with the sun gear;

[0014] The gear ring is rotatably mounted inside the housing via a bearing. The first end of the gear ring is provided with an internal gear ring that meshes with the planetary gear, and the second end is connected to the nut.

[0015] As a preferred embodiment of this utility model, a sleeve is provided on the outside of the nut, and the sleeve is connected to the first end of the outer shell.

[0016] As a preferred technical solution of this utility model, the thrust assembly includes a thrust seat, which is connected to the inner wall of the outer shell through a guide anti-rotation structure, so that the thrust seat is constrained to be able to move only along the axial direction of the outer shell;

[0017] The first end of the thrust seat is used to connect with the caliper, and its second end is connected to the first end of the ball screw.

[0018] As a preferred technical solution of this utility model, it also includes a stop structure for limiting the axial movement limit of the ball screw during the reset stroke;

[0019] The stop structure includes a positioning block disposed on the second end face of the thrust seat and a limiting block disposed on the first end face of the nut.

[0020] When the ball screw returns to the first limit position, the positioning block abuts against the limit block to prevent the nut from continuing to rotate.

[0021] As a preferred technical solution of this utility model, when the positioning block and the limiting block are in axial contact, the axial distance between them is less than the lead of the ball screw for one revolution.

[0022] As can be seen from the above technical solutions, the present invention provides a transmission mechanism for an electronic brake assist system, which has the following advantages compared with the prior art:

[0023] The transmission mechanism of this invention features a compact structure and high space utilization. By designing the motor's output shaft as a hollow structure and installing the ball screw within it, radial space is effectively utilized, significantly shortening the overall axial length of the transmission mechanism. This layout optimizes the axial and radial space allocation, solving the problem of excessively large axial dimensions caused by the coaxial series arrangement of the ball screw and motor in existing technologies. It significantly improves the adaptability and flexibility of the transmission mechanism within the confined space of a vehicle.

[0024] The compact overall layout brings the center of gravity of the mechanism closer to the fixed point, effectively reducing the additional bending moment caused by vehicle swaying under bumpy road conditions, improving the structural rigidity and long-term operational stability of the transmission mechanism and its connecting components, and helping to extend its service life.

[0025] Key components such as the sun gear, planetary gears, and gear ring are connected by press fitting and bolts, which simplifies the assembly process while ensuring connection strength, and is conducive to large-scale production and later maintenance.

[0026] The transmission is reliable and the stopping method is optimized. This utility model innovatively sets protruding structures on both the thrust seat and the nut, and achieves rotational stopping through the contact and engagement of the two protruding blocks. This stopping method does not rely on the ball screw to bear the load, fundamentally avoiding the huge axial impact force caused by end face stopping, greatly reducing the risk of ball screw jamming, improving the smoothness and reliability of the transmission process, and at the same time reducing the material and structural design requirements of related components.

[0027] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below can be considered as part of the utility model subject matter of this disclosure, provided that such concepts do not contradict each other.

[0028] The foregoing and other aspects, embodiments, and features of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0029] The accompanying drawings are not drawn to scale according to a true reference numeral. In the drawings, each identical or nearly identical component shown in the various figures can be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, wherein:

[0030] Figure 1 This is a cross-sectional view of the transmission mechanism of this utility model;

[0031] Figure 2 This is a schematic diagram of the motor structure of this utility model;

[0032] Figure 3 This is a schematic diagram of the ball screw pair structure of this utility model.

[0033] The meanings of the reference numerals in the figure are as follows:

[0034] 1. Housing; 2. Motor; 3. Output shaft; 4. Ball screw; 5. Thrust seat; 6. Nut; 7. Sun gear; 8. Planetary gear; 9. Gear ring; 10. Sleeve; 11. Positioning block; 12. Limiting block. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the described embodiments of this utility model without creative effort are within the scope of protection of this utility model. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this utility model pertains.

[0036] The terms "first," "second," and similar words used in this utility model patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "an," "a," or "the," etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. Terms such as "comprising" or "including" indicate that the element or object preceding "comprising" encompasses the features, integrals, steps, operations, elements, and / or components listed following "comprising" or "including," and do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0037] This invention addresses the technical problem that existing brakes have a long axial structure, which increases the difficulty of vehicle layout and may even make installation impossible. It provides a transmission mechanism for electronic brake assist systems.

[0038] The transmission mechanism of this utility model mainly includes a power component, a transmission component, a ball screw pair, and a thrust component. By optimizing the structural layout between the components, the axial length and volume are reduced, making the layout of each component more reasonable, thereby making the arrangement of the components of the whole vehicle more convenient and simple.

[0039] To provide protection for the various components and parts of the transmission mechanism, the power assembly, transmission assembly, ball screw pair, thrust assembly, etc., are all housed within a housing 1. The thrust assembly, ball screw pair, transmission assembly, and power assembly are sequentially installed from the first end to the second end of the housing 1. In some specific embodiments of this utility model, the second end of the housing 1 is also provided with components or modules such as a parking assembly and a control module commonly used with brakes; these will not be described in detail here.

[0040] The power assembly includes a motor 2 and an output shaft 3. Specifically, as shown... Figure 1 As shown, motor 2 is mounted inside the center of housing 1 via a mounting bracket, providing power to the entire transmission mechanism; as Figure 2 As shown, the output shaft 3 is installed at the output end of the motor 1, and its axis coincides with the center of the housing 1, with its central axis serving as the axis of symmetry for the entire transmission mechanism. To reduce the axial length of the transmission mechanism, the output shaft 3 is designed as a hollow structure to replace the traditional solid output shaft. The hollow structure, in conjunction with the ball screw 4, makes efficient use of the radial space of the output shaft 3. Specifically, a cylindrical mounting cavity is formed at the center of the output shaft 3. This cavity is used to mount the second end of the ball screw 4, allowing the longer axial portion of the ball screw 4 to extend into the output shaft 3. This fully utilizes part of the space in the output shaft 3, making the previously "idle" hollow structure of the output shaft 3 accommodate the second end of the ball screw 4, thus effectively utilizing the output shaft 3 and achieving space sharing.

[0041] The thrust assembly includes a thrust seat 5, which is connected to the first end of the housing 1 via a guide anti-rotation structure. This guide anti-rotation structure can employ a key-and-slot mating structure to constrain the circumferential rotation of the thrust seat 5, allowing only axial linear movement. The first end of the thrust seat 5 is connected to a caliper, and its second end is connected to the first end of the ball screw 4 via a threaded connection, enabling it to move synchronously with the ball screw 4. Because the key-and-slot mating connection prevents the thrust seat 5 from rotating relative to the housing 1, allowing only axial linear movement, the connected ball screw 4 is also restricted from circumferential rotation, only allowing axial extension or retraction. When the thrust seat 5 is extended by the ball screw 4 and forced to move axially linearly towards the first end of the housing 1, the first end of the thrust seat 5 contacts the caliper, pushing the caliper to clamp and forming a braking effect; when the ball screw 4 retracts and drives the thrust seat 5 to move axially linearly towards the second end of the housing 1, the first end of the thrust seat 5 moves away from the caliper, releasing the pressure on the caliper and canceling the braking effect.

[0042] The ball screw assembly includes a nut 6 and a ball screw 4, such as Figure 3 As shown, nut 6 is threadedly connected to ball screw 4. Nut 6 is the fixed end, and it is driven to rotate by gear ring 9, converting the circumferential rotational motion into the axial linear motion of ball screw 4. Figure 1 As shown, the first end of the ball screw 4 is connected to the second end of the thrust seat 5, and its second end is coaxially mounted in the mounting cavity of the output shaft 3. When the ball screw 4 moves, the mounting cavity also serves as a guide and limiter, increasing the smoothness of the ball screw 4's movement. Because a portion of the length of the ball screw 4 overlaps with the output shaft 3, the overall axial length of the entire transmission mechanism is shortened, significantly improving structural compactness. This solves the technical problem of existing brakes using a solid output shaft, which results in no usable space for the coaxially arranged ball screw 4, leading to an excessively long overall axial length of the brake.

[0043] Among them, such as Figure 3 As shown, the nut 6 is threaded onto the outside of the ball screw 4, and a sleeve 10 is fitted around the nut 6. The sleeve 10 is connected to the inner wall of the outer casing 1. With this structure, the sleeve 10 provides axial positioning for the nut 6, restricting its axial displacement, but allowing the nut 6 to rotate freely axially around the axis of the ball screw 4 within the sleeve 10.

[0044] like Figure 1 As shown, the transmission assembly includes a sun gear 7, a planetary gear 8, and a gear ring 9. The sun gear 7 is mounted outside the output shaft 3 via key and keyway fit, interference fit, or other connection methods, and rotates synchronously with the output shaft 3. The planetary gear 8 is mounted on the inner side wall of the housing 1 via a planetary shaft and meshes with the sun gear 7. The gear ring 9 is rotatably mounted inside the housing 1 via a bearing seat, located outside the sun gear 7 and planetary gear 8. The first end of the gear ring 9 has an internal gear ring for meshing with the planetary gear 8, and its second end is connected to the nut 6. When the motor 2 drives the output shaft 3 to rotate, it synchronously drives the sun gear 7 to rotate. The sun gear 7 drives the gear ring 9 to rotate via the planetary gear 8, and finally the gear ring 9 drives the nut 6 to rotate, realizing the sequential transmission of power. The rotational motion of the nut 6 is converted into the axial linear motion of the ball screw 4 by the threaded connection between the nut 6 and the ball screw 4.

[0045] Furthermore, to prevent the ball screw 4 from resetting beyond its limit when the brake is released, a stop structure is designed to stop the movement of the ball screw 4 when it resets to the first limit. Specifically, the stop structure includes a positioning block 11 and a limiting block 12. The positioning block 11 is located on the second end edge of the thrust seat 5 and protrudes from that end face. The limiting block 12 is located on the first end edge of the nut 6 and protrudes from that end face. The axial distance between the positioning block 11 and the limiting block 12 when they are in contact is less than the lead of one revolution of the ball screw 4. When the positioning block 11 and the limiting block 12 are in contact, they abut against each other, thereby achieving the stopping effect.

[0046] Specifically, during the operation of the transmission mechanism, the nut 6, as the fixed end, is constrained to rotate only circumferentially, while the ball screw 4, which has no axial displacement, is connected to the guide anti-rotation structure of the housing 1 through the thrust assembly and is restricted to linear axial movement only, without circumferential rotation. When the nut 6 rotates, its rotation direction (forward or reverse) determines the axial movement direction of the ball screw 4: one rotation direction causes the ball screw 4 to retract towards the second end of the housing 1, i.e., the reset stroke; the other rotation direction causes the ball screw 4 to extend towards the first end of the housing 1, i.e., the braking stroke. During the reset stroke, the ball screw 4 drives the thrust seat 5 to move towards the nut 6, causing the positioning block 11 at the second end of the thrust seat 5 to gradually approach the limiting block 12 at the first end of the nut 6. When the ball screw 4 resets to the first limit, the positioning block 11 and the limiting block 12 come into axial contact. Because the circumferential distance between the positioning block 11 and the limiting block 12 is less than the lead of one rotation of the ball screw 4, this contact will forcibly prevent the nut 6 from continuing to rotate, thereby stopping the axial movement of the ball screw 4 and achieving precise stopping. Conversely, during the braking stroke, the ball screw 4 drives the thrust seat 5 away from the nut 6, and the positioning block 11 and the limiting block 12 are always separated and will not contact each other. Therefore, the rotation of the nut 6 is unrestricted, ensuring smooth braking.

[0047] This utility model embodiment uses a stop structure in the direction of rotation. At the moment of stopping, the balls of the ball screw 4 no longer bear force, thereby protecting the balls of the ball screw 4 from being jammed and preventing the generation of huge axial force. It also reduces the difficulty of designing other components.

[0048] The working principle of this utility model embodiment is as follows:

[0049] When the brake is released, motor 2 drives nut 6 to rotate forward via transmission assembly, causing ball screw 4 to move towards the second end of housing 1. Since the first end of ball screw 4 is connected to the second end of thrust seat 5, it synchronously drives thrust seat 5 towards the second end of housing 1. When it reaches the first limit, the limit block 12 on nut 6 contacts the positioning block 11 on thrust seat 5. Because thrust seat 5 cannot rotate, nut 6 stops rotating due to stroke limitation. When nut 6 rotates in the reverse direction, pushing ball screw 4 and thrust seat 5 towards the first end of housing 1, it is equivalent to thrust seat 5 moving away from nut 6. Positioning block 11 and limit block 12 no longer contact each other, releasing the aggression. This design avoids the adverse consequences of the huge axial force generated by the axial end face stop structure and improves the stability of the mechanism.

[0050] This utility model embodiment, through innovative spatial layout and stop structure design, effectively overcomes the technical defects of existing electromechanical brakes, such as long axial dimensions, unreasonable space utilization, poor stop reliability, and susceptibility to impact loads, while ensuring braking performance. It has comprehensive advantages such as compact structure, fast braking response, stable and reliable operation, and easy assembly and maintenance, and is suitable for promotion and application in electronic brake assist systems of commercial vehicles.

[0051] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Those skilled in the art to which this invention pertains can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of this invention shall be determined by the claims.

Claims

1. A transmission mechanism for an electronic brake assist system, comprising a housing (1), wherein a thrust assembly, a ball screw pair, a transmission assembly, and a power assembly are sequentially arranged from a first end to a second end within the housing (1), characterized in that, The power assembly includes a motor (2) and an output shaft (3). The output shaft (3) is a hollow shaft coaxially located at the output end of the motor (2), and a cylindrical mounting cavity is formed inside it. The ball screw assembly includes a ball screw (4) and a nut (6) that is threaded to it. The first end of the ball screw (4) is connected to the thrust assembly, and the second end of the ball screw (4) extends coaxially into the mounting cavity. The nut (6) is axially fixed and rotates only circumferentially, while the ball screw (4) is circumferentially fixed and moves only axially in a linear fashion.

2. The transmission mechanism for an electronic brake assist system according to claim 1, characterized in that, The transmission assembly includes a sun gear (7), a planetary gear (8), and a gear ring (9). The sun gear (7) is fixedly mounted on the outside of the output shaft (3); The planetary gear (8) is mounted on the inner wall of the housing (1) via a planetary shaft and meshes with the sun gear (7); The gear ring (9) is rotatably mounted inside the housing (1) via a bearing. The first end of the gear ring (9) is provided with an internal gear ring that meshes with the planetary gear (8), and the second end is connected to the nut (6).

3. The transmission mechanism for an electronic brake assist system according to claim 1, characterized in that, A sleeve (10) is fitted around the nut (6), and the sleeve (10) is connected to the first end of the outer shell (1).

4. The transmission mechanism for an electronic brake assist system according to claim 1, characterized in that, The thrust assembly includes a thrust seat (5), which is connected to the inner wall of the outer shell (1) through a guide anti-rotation structure, so that the thrust seat (5) is constrained to be able to move only along the axial direction of the outer shell (1); The first end of the thrust seat (5) is used to connect with the caliper, and its second end is connected to the first end of the ball screw (4).

5. The transmission mechanism for an electronic brake assist system according to claim 4, characterized in that, It also includes a stop structure for limiting the axial movement limit of the ball screw (4) during the reset stroke; The stop structure includes a positioning block (11) on the second end face of the thrust seat (5) and a limiting block (12) on the first end face of the nut (6). When the ball screw (4) is reset to the first limit position, the positioning block (11) abuts against the limit block (12) to prevent the nut (6) from continuing to rotate.

6. The transmission mechanism for an electronic brake assist system according to claim 5, characterized in that, When the positioning block (11) and the limiting block (12) are in axial contact, the axial distance between them is less than the lead of one revolution of the ball screw (4).

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