A shaft assembly and drum brake assembly

Abstract

The application discloses a rotating shaft assembly and a drum brake assembly, wherein the rotating shaft assembly comprises a mandrel and a bushing sleeved on the mandrel; the bushing comprises an outer surface and an inner surface, the inner surface of the bushing comprises a first bushing guide portion and a second bushing guide portion, the surface of the mandrel comprises a first mandrel guide portion and a second mandrel guide portion, the first bushing guide portion is matched with the first mandrel guide portion so that the bushing can move relative to the mandrel in a first direction, the second bushing guide portion is matched with the second mandrel guide portion so that the bushing can move relative to the mandrel in a second direction, and the brake shoe can rotate relative to the circumferential surface of the outer surface of the bushing; the first direction and the second direction are both in a plane perpendicular to the axial direction of the mandrel. Two independent relative movements exist between the bushing and the brake shoe and the mandrel, the movement of the brake shoe is in plane superposition with the inner side of the brake drum, and the problem of uneven friction of the drum brake is solved.

Description

Technical Field

[0001] This invention relates to the field of braking technology, specifically to a rotating shaft assembly and a drum brake assembly. Background Technology

[0002] Existing friction brakes are mainly divided into drum brakes, disc brakes, and band brakes. Drum brakes typically use a brake transmission mechanism to press the brake friction pads against the inside of the brake drum, thereby generating braking force to slow down or stop the wheels. The brake shoes are supported by a fixed-axis rotation and a floating support to ensure that the brake friction pads are pressed tightly against the inside of the brake drum.

[0003] However, after long-term use, the brake friction pads of current drum brakes will wear unevenly, which can easily lead to a series of problems such as insufficient braking force, chafing, locking, noise, sideslip, fishtailing, deviation, dragging, uneven wear, and unbalanced force on the drive shaft. One of the main reasons for uneven wear of brake pads is that the movement of the brake shoes cannot make the brake friction pads overlap with the curved plane inside the brake drum.

[0004] Therefore, if the movement of the brake shoes cannot be made to overlap with the inner side of the brake drum in a planar manner, the series of problems caused by uneven friction in the current drum brakes cannot be fundamentally solved. Summary of the Invention

[0005] To enable the movement of the brake shoe to form a planar superposition movement with the inner side of the brake drum, the first objective of this application is to provide a rotating shaft assembly connected to the brake shoe, which can rotate around the rotating shaft assembly to move closer to or away from the brake drum. The rotating shaft assembly in this application includes a spindle and a bushing sleeved on the spindle. The bushing can move relative to the spindle in a first direction or a second direction. Both the first and second directions are in a plane perpendicular to the axial direction of the spindle. The brake shoe can rotate relative to the circumferential surface of the outer surface of the bushing. Therefore, the bushing in the rotating shaft assembly of this application can translate in a first direction or a second direction. The outer surface of the bushing also has a circumferential surface that can rotate relative to the brake shoe. This enables the brake shoe connected to the bushing to have a fixed-axis rotation and translational motion in the first and second directions. The fixed-axis rotation and translational motion are independent of each other. Thus, the brake shoe can have two degrees of freedom of movement, that is, it can move on the plane that combines the fixed-axis rotation and the parallel translation. The movement of the brake shoe can form a planar superposition motion with the cylindrical inner surface of the brake drum. This not only enables the brake friction pads to completely superimpose with the cylindrical inner surface of the brake drum, so that the friction can be evenly distributed along the cylindrical inner surface of the brake drum, but also generates a larger and more stable friction force by increasing the superposition surface.

[0006] The second objective of this application is to provide a drum brake assembly in which one end of the brake shoe assembly is connected to the aforementioned rotating shaft assembly, and the brake shoe assembly can rotate around the rotating shaft assembly. This allows the other end of the brake shoe assembly to approach the brake drum along a first or second direction. The combination of the circumferential rotation of the brake shoe assembly and its translational motion in the first or second direction enables it to form a planar overlapping motion with the brake drum. This not only allows the brake friction pads to completely overlap with the cylindrical inner surface of the brake drum, ensuring uniform friction distribution along the cylindrical inner surface of the brake drum, but also generates greater and more stable friction by increasing the overlapping surface area. This fundamentally solves a series of problems caused by uneven friction in current drum brakes, such as insufficient braking force, wear, locking, noise, sideslip, tail-wagging, deviation, drag, uneven wear, and unbalanced drive shaft forces.

[0007] The rotating shaft assembly of this application adopts the following technical solution:

[0008] A rotating shaft assembly is provided, the rotating shaft assembly being connected to a brake shoe, the brake shoe being rotatable about the rotating shaft assembly to move closer to or away from a brake drum. The rotating shaft assembly of this application includes a spindle and a bushing sleeved on the spindle; the bushing includes an outer surface and an inner surface, the inner surface of the bushing including a first bushing guide portion and a second bushing guide portion, the surface of the spindle including a first spindle guide portion and a second spindle guide portion, the first bushing guide portion cooperating with the first spindle guide portion to allow the bushing to move relative to the spindle in a first direction, the second bushing guide portion cooperating with the second spindle guide portion to allow the bushing to move relative to the spindle in a second direction, the outer surface of the bushing including a circumferential surface, the brake shoe being rotatable relative to the circumferential surface of the outer surface of the bushing; the bushing having an initial position relative to the spindle, at which the first bushing guide portion cooperates with the first spindle guide portion and the second bushing guide portion cooperates with the second spindle guide portion; both the first direction and the second direction are in a plane perpendicular to the axial direction of the spindle.

[0009] As described above, the mandrel is fixed in position, and the bushing is fitted onto the mandrel, positioned between the brake shoe and the mandrel. The bushing, brake shoe, and mandrel each have two relative movements. First, the bushing can translate relative to the mandrel along a first direction, and also along a second direction. The first and second directions are two different directions within a plane perpendicular to the axial direction of the mandrel. Second, the outer surface of the bushing includes a circumferential surface, and the brake shoe can rotate relative to this circumferential surface, achieving relative rotation between the brake shoe and the bushing.

[0010] In the initial position, the bushing and mandrel cannot move relative to each other due to the mutual engagement between the first bushing guide and the first mandrel guide, the second bushing guide and the second mandrel guide. Only when the bushing and mandrel rotate relative to each other, causing the bushing to leave the initial position relative to the mandrel, thus disengaging the first bushing guide from the first mandrel guide or the second bushing guide from the second mandrel guide, can the bushing and mandrel move relative to each other in the first or second direction.

[0011] In this way, the bushing can translate relative to the spindle in a first or second direction. The outer surface of the bushing also has a circumferential surface that can rotate relative to the brake shoe. This allows the brake shoe connected to the bushing to have a fixed-axis rotation and translational motion in the first and second directions, with the fixed-axis rotation and translational motion being independent of each other. Thus, the shaft assembly enables the brake shoe to have two degrees of freedom of movement: the brake shoe can move on the plane combining the fixed-axis rotation and parallel translation, and the movement of the brake shoe can form a planar superposition motion with the cylindrical inner surface of the brake drum. This not only allows the brake friction pads to completely superimpose with the cylindrical inner surface of the brake drum, ensuring that friction is evenly distributed along the cylindrical inner surface of the brake drum, but also generates a larger and more stable frictional force by increasing the superposition surface. This fundamentally solves a series of problems caused by uneven friction in current drum brakes, such as insufficient braking force, wear, lock-up, noise, sideslip, fishtailing, deviation, drag, uneven wear, and unbalanced drive shaft forces.

[0012] As an optional implementation of the pivot assembly of this application, the first bushing guide portion includes a first bushing guide plane along the first direction; the second bushing guide portion includes a second bushing guide plane along the second direction; the first spindle guide portion includes a first spindle guide plane along the first direction; the second spindle guide portion includes a second spindle guide plane along the second direction; the first bushing guide plane is capable of abutting against the first spindle guide plane; the second bushing guide plane is capable of abutting against the second spindle guide plane; at the initial position, the first bushing guide plane abuts against the first spindle guide plane, and the second bushing guide plane abuts against the second spindle guide plane.

[0013] This design limits the first bushing guide, the first spindle guide, the second bushing guide, and the second spindle guide to all being planar, which reduces the difficulty and cost of machining and makes the installation between the bushing and the spindle more convenient and reliable.

[0014] As an optional implementation of the pivot assembly of this application, the first spindle guide plane is adjacent to the second spindle guide plane, one end of the first spindle guide plane and one end of the second spindle guide plane are connected at their intersection, and the other end of the first spindle guide plane and the other end of the second spindle guide plane are connected by a spindle curved surface, the spindle curved surface including a first spindle curved surface adjacent to the first spindle guide plane and a second spindle curved surface adjacent to the second spindle guide plane; the first bushing guide plane is adjacent to the second bushing guide plane, the first bushing guide plane... One end of the first bushing guide plane is connected to one end of the second bushing guide plane at their intersection. The other end of the first bushing guide plane is connected to the other end of the second bushing guide plane through a bushing curved surface. The bushing curved surface includes a first bushing curved surface adjacent to the first bushing guide plane and a second bushing curved surface adjacent to the second bushing guide plane. The bushing moves relative to the mandrel in a first direction so that the first bushing curved surface can abut against the first mandrel curved surface. The bushing moves relative to the mandrel in a second direction so that the second bushing curved surface can abut against the second mandrel curved surface.

[0015] Thus, the first mandrel guide plane and the second mandrel guide plane are adjacent and connected at their intersection. The ends of the first and second mandrel guide planes away from their intersection are connected by a mandrel curved surface, that is, the ends of the first and second mandrel guide planes away from their intersection are connected by an arcuate surface. Similarly, the first bushing guide plane and the second bushing guide plane are adjacent and connected at their intersection. The ends of the first and second bushing guide planes away from their intersection are connected by a bushing curved surface, that is, the ends of the first and second bushing guide planes away from their intersection are connected by an arcuate surface. Furthermore, when the bushing moves relative to the mandrel in the first direction, the first bushing curved surface can abut against the first mandrel curved surface; when the bushing moves relative to the mandrel in the second direction, the second bushing curved surface can abut against the second mandrel curved surface. This allows the bushing and mandrel to rotate relative to each other to a certain extent along the arcuate surface, supporting relative translation between the bushing and mandrel in the first or second direction.

[0016] As an optional implementation of the rotating shaft assembly of this application, the bushing further includes a limiting portion, wherein the bushing abuts against the spindle at the limiting portion, and in the circumferential direction of the spindle, the limiting portion is opposite to the intersection of the first bushing guide plane and the second bushing guide plane.

[0017] Thus, in the circumferential direction of the mandrel, one side of the first bushing curved surface is connected to the first bushing guide plane, and the other side is connected to the limiting part; one side of the second bushing curved surface is connected to the second bushing guide plane, and the other side is connected to the limiting part. The limiting part can prevent the connection between the first bushing curved surface and the second bushing curved surface along the arc surface. The limiting part can restrict the movement of the first mandrel curved surface within the first bushing curved surface, and restrict the movement of the second mandrel curved surface within the second bushing curved surface, preventing the first bushing curved surface and the second mandrel curved surface from abutting against each other, and also preventing the second bushing curved surface and the first mandrel curved surface from abutting against each other. That is, the limiting part can limit the amplitude of relative rotation between the bushing and the mandrel, so that the bushing and the mandrel cannot be relatively flipped.

[0018] As an optional implementation of the pivot assembly of this application, the bushing further includes a first bushing auxiliary guide plane, which is connected to the limiting portion and extends along the first direction; the bushing further includes a second bushing auxiliary guide plane, which is connected to the limiting portion and extends along the second direction.

[0019] Thus, the first bushing auxiliary guide plane and the second bushing auxiliary guide plane can further prevent relative flipping between the bushing and the mandrel.

[0020] As an optional implementation of the pivot assembly of this application, the spindle includes a sector-shaped shaft, with an included angle formed between the first spindle guide portion and the second spindle guide portion, the included angle being directed toward the axis of the spindle, and the first spindle guide portion and the second spindle guide portion being symmetrical with respect to the diameter of the spindle.

[0021] Thus, the first spindle guide and the second spindle guide are symmetrical with respect to the diameter of the spindle, making the structure of the spindle symmetrical, which in turn makes the bushing structure that mates with the spindle symmetrical, thereby making the overall structure of the rotating shaft assembly balanced and the force balanced.

[0022] As an optional implementation of the pivot assembly of this application, the spindle includes a notched shaft, and an included angle is formed between the first spindle guide portion and the second spindle guide portion, the included angle being oriented away from the axis of the spindle, and the first spindle guide portion and the second spindle guide portion are symmetrical with respect to the diameter of the spindle.

[0023] Therefore, the mandrel has a notch, which facilitates its installation and removal. Simultaneously, the first and second mandrel guide sections are symmetrical with respect to the diameter of the mandrel, ensuring structural symmetry of the mandrel and consequently, symmetry of the bushing structure that mates with it. This results in overall structural balance and force balance for the rotating shaft assembly.

[0024] As an optional implementation of the pivot assembly of this application, the spindle includes a guide section located in the middle of the spindle and mounting portions located at both ends of the spindle, and the bushing is sleeved on the guide section of the spindle.

[0025] Thus, the bushing is located in the guide section in the middle of the mandrel. The guide section facilitates the installation and disassembly of the bushing and the mandrel. The mounting parts at both ends of the mandrel facilitate the fixed installation of the mandrel and can also limit the bushing during installation.

[0026] As an optional implementation of the pivot assembly of this application, the spindle includes at least one mounting guide surface located at the end of the spindle such that the outermost end profile of the spindle has a reduced diameter.

[0027] Therefore, when the mandrel is installed on the mounting base, the mounting guide surface can play a guiding role, making the installation more convenient.

[0028] As an optional implementation of the pivot assembly of this application, the spindle has an outer diameter R1, the outermost end profile of the spindle has a reduced diameter R2, the bushing has a travel length L1 relative to the movement of the spindle in the first direction, and the bushing has a travel length L2 relative to the movement of the spindle in the second direction; R1-R2>L1, and R1-R2>L2.

[0029] Therefore, the travel length L1 of the bushing relative to the spindle in the first direction and the travel length L2 of the bushing relative to the spindle in the second direction are both less than the difference between the outer diameter of the bushing and the diameter of the outermost end, which limits the relative movement between the bushing and the spindle in the first and second directions.

[0030] As an optional implementation of the rotating shaft assembly of this application, the travel length of the bushing relative to the spindle along the first direction is equal to the travel length of the bushing relative to the spindle along the second direction, i.e., L1 = L2.

[0031] This ensures that the relative movement between the bushing and the spindle is symmetrical in the first and second directions, achieving motion balance between the bushing and the spindle, and consequently, motion balance of the brake shoes.

[0032] The drum brake assembly of this application adopts the following technical solution:

[0033] A drum brake assembly includes a brake drum, a brake shoe assembly, an actuator, and a mounting base. The actuator is brakely connected to one end of the brake shoe assembly to drive the brake shoe assembly to move toward the brake drum. The drum brake assembly of this application also includes any of the aforementioned rotating shaft assemblies. The spindle is fixedly mounted on the mounting base. The other end of the brake shoe assembly is rotatably connected to the bushing so that the brake shoe assembly can rotate relative to the bushing and can move toward the brake drum along the first direction or the second direction with the bushing.

[0034] The working process is as follows: The actuator drives the brake shoe assembly to expand outward. While the brake shoe assembly rotates around the bushing's fixed axis, the bushing can move relative to the spindle in a first or second direction according to the braking direction. Consequently, the brake shoe can approach the brake drum along the first or second direction, and the friction pads of the brake shoe assembly can adhere to the brake drum along the first or second direction under the braking force. Since the rotation and movement along the first or second direction of the brake shoe assembly are independent movements, while the brake shoe assembly drives the friction pads to rotate, the friction pads can completely overlap with the cylindrical inner surface of the brake drum at a certain point in the first or second direction. When the friction pads completely overlap with the cylindrical inner surface of the brake drum, the reaction force will stop the brake shoe assembly in the braking position, keeping the friction pads and the cylindrical inner surface of the brake drum in a completely overlapped position. Due to the complete overlap, the wear of all parts of the friction pads is uniform, and because of the complete overlap, the overlap surface is the largest, that is, the friction area is the largest, thus generating the largest and most stable friction force.

[0035] Therefore, the combination of the circumferential rotation of the brake shoe assembly and its translational motion in the first and second directions enables it to form a planar overlapping motion with the brake drum. This not only allows the brake friction pads to completely overlap with the cylindrical inner surface of the brake drum, ensuring that friction is evenly distributed along the cylindrical inner surface of the brake drum, but also generates a larger and more stable frictional force by increasing the overlapping surface. This fundamentally solves a series of problems caused by uneven friction in current drum brakes, such as insufficient braking force, wear, lock-up, noise, sideslip, fishtailing, deviation, drag, uneven wear, and unbalanced force on the drive shaft.

[0036] As an optional implementation of the drum brake assembly of this application, the drum brake assembly further includes an outer ring, which is fixedly connected to the brake shoe assembly and rotatably connected to the bushing.

[0037] Thus, the outer ring is located between the bushing and the brake shoe assembly. The outer ring is fixedly connected to the brake shoe assembly. The outer ring can be fitted over the bushing to achieve a rotatable connection between the outer ring and the bushing. When the brake shoe assembly and the bushing rotate relative to each other, the outer ring can bear most of the friction, thereby protecting the connection between the brake shoe assembly and the bushing and extending the service life of the brake shoe assembly and the bushing. The outer ring is a detachable component, and the replacement cost is low.

[0038] As an optional implementation of the drum brake assembly of this application, the brake shoe assembly includes a reverse shoe assembly and a forward shoe assembly. The reverse shoe assembly is connected to a first rotating shaft assembly, and the forward shoe assembly is connected to a second rotating shaft assembly. A first direction of the first rotating shaft assembly extends radially outward from the initial position of the first rotating shaft assembly. A first direction of the second rotating shaft assembly extends radially outward from the initial position of the second rotating shaft assembly.

[0039] Thus, in the initial position, the first direction of the first rotating shaft assembly is radially outward along the radial direction of the reverse shoe assembly, and the first direction of the second rotating shaft assembly is radially outward along the radial direction of the forward shoe assembly.

[0040] As an optional implementation of the drum brake assembly of this application, the second direction of the first rotating shaft assembly has an angle θ1 with the first direction of the first rotating shaft assembly; the second direction of the second rotating shaft assembly has an angle θ2 with the first direction of the second rotating shaft assembly; 80°<θ1<160′, 80′<θ2<160′.

[0041] The first direction affects the normal driving braking force, and the second direction affects the reversing braking force. The angle between the first and second directions determines the balance of braking force between the reverse and forward brake components in driving and reversing, respectively. Experiments have shown that the range of 80′<θ1<160° and 80°<θ2<160° is the most stable and appropriate.

[0042] As an optional implementation of the drum brake assembly of this application, the brake drum has a center O1, the first shaft assembly has a center D1, the second shaft assembly has a center D2, the line connecting the center O1 of the brake drum to the center D1 of the first shaft assembly and the center D2 of the second shaft assembly has a distance H, the distance between the center D1 of the first shaft assembly and the center D2 of the second shaft assembly is L, the bushing has an outer diameter R, and the first direction has an angle α with the horizontal plane, where: 2H / (L+2R) <Tanα<2H / L。

[0043] Therefore, the distance between the intersection of the first spindle guide A11 and the second spindle guide A12 of the first rotating shaft assembly C1 and the intersection of the first spindle guide A11 and the second spindle guide A12 of the second rotating shaft assembly C2 is greater than L and less than L+2R.

[0044] As an optional implementation of the drum brake assembly of this application, the angle θ1 between the second direction of the first rotating shaft assembly and the first direction of the first rotating shaft assembly and the angle θ2 between the second direction of the second rotating shaft assembly and the first direction of the second rotating shaft assembly satisfy: θ1=θ2; the angle α1 between the first direction of the first rotating shaft assembly and the horizontal plane and the angle α2 between the first direction of the second rotating shaft assembly and the horizontal plane satisfy: α1=α2.

[0045] Therefore, with the diameter of the brake drum as the axis of symmetry, the first direction of the first rotating shaft assembly is symmetrical with the first direction of the second rotating shaft assembly, and the second direction of the second rotating shaft assembly is symmetrical with the second rotating shaft assembly. That is, the installation positions and installation angles of the first rotating shaft assembly and the second rotating shaft assembly are symmetrical to each other, so that the relative movements of the reverse shoe assembly and the forward shoe assembly are symmetrical to each other, and the braking process of the drum brake assembly is balanced and stable.

[0046] As an optional implementation of the drum brake assembly of this application, the angle α1 between the first direction of the first rotating shaft assembly and the horizontal plane and the angle α2 between the first direction of the second rotating shaft assembly and the horizontal plane satisfy 68°<α1<82° and 68°<α2<82°.

[0047] If the angle between the first direction of the first rotating shaft assembly and the horizontal plane is too small, the angle between the first direction and the second direction of the first rotating shaft assembly will be too sharp, resulting in greater wear on the front end of the brake shoe assembly. If the angle between the first direction of the first rotating shaft assembly and the horizontal plane is too large, the angle between the second direction and the second opposite direction of the first rotating shaft assembly will be too rounded, resulting in excessive braking force and excessive sensitivity. The same applies to the second rotating shaft assembly. Therefore, the angle between the first direction and the horizontal plane affects the movement path of the brake shoe assembly during the overlapping process with the brake drum. The overlapping movement path affects the braking force and the wear on the front end of the brake shoe assembly. Comprehensive experiments have shown that the numerical range of 68° < α1 < 82° and 68° < α2 < 82° is the most balanced.

[0048] As an optional implementation of the drum brake assembly of this application, the inner surface of the brake drum and the outer surface of the friction pad of the brake shoe assembly have an initial distance D; the bushing has a travel length L1 relative to the spindle in the first direction, and the bushing has a travel length L2 relative to the spindle in the second direction; wherein, L1≥D, L2≥D.

[0049] Thus, when the bushing moves relative to the spindle in the first direction, the movement distance of the brake shoe assembly in the first direction is sufficient for the friction pads of the brake shoe assembly to overlap with the inner surface of the brake drum; when the bushing moves relative to the spindle in the second direction, the movement distance of the brake shoe assembly in the second direction is sufficient for the friction pads of the brake shoe assembly to overlap with the inner surface of the brake drum. Attached Figure Description

[0050] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0051] Figure 1 This is a schematic diagram of the structure of a drum brake assembly in a non-braking state according to an illustrative embodiment of this application;

[0052] Figure 2 for Figure 1 Schematic diagram of the cross-sectional structure of AA;

[0053] Figure 3 This is a schematic diagram of the service braking state of a drum brake assembly in one illustrative embodiment of this application;

[0054] Figure 4 for Figure 3 Enlarged view of the structure at point G in the middle;

[0055] Figure 5 This is a schematic diagram of the service braking state of a drum brake assembly in one illustrative embodiment of this application;

[0056] Figure 6 This is a schematic diagram of the reverse braking state of a drum brake assembly in one illustrative embodiment of this application;

[0057] Figure 7 This is a three-dimensional structural diagram of a rotating shaft assembly in one illustrative embodiment of this application;

[0058] Figure 8 This is a front view of a rotating shaft assembly in one illustrative embodiment of this application;

[0059] Figure 9 This is a top view of a rotating shaft assembly in one illustrative embodiment of this application;

[0060] Figure 10 This is a schematic diagram of the right side of a rotating shaft assembly in one illustrative embodiment of this application;

[0061] Figure 11This is a three-dimensional structural diagram of a bushing of a rotating shaft assembly in one illustrative embodiment of this application;

[0062] Figure 12 This is a three-dimensional structural diagram of the spindle of a rotating shaft assembly in one illustrative embodiment of this application;

[0063] Figure 13 This is a three-dimensional structural diagram of a rotating shaft assembly in one illustrative embodiment of this application.

[0064] Explanation of reference numerals in the attached figures:

[0065] A. Rotary shaft assembly;

[0066] A1. Mandrel; A11. First mandrel guide section; A111. First mandrel guide plane; A12. Second mandrel guide section; A121. Second mandrel guide plane; A13. Mandrel curved surface; A131. First mandrel curved surface; A132. Second mandrel curved surface; A14. Guide section; A15. Mounting part; A16. Notch; A17. Mounting guide surface;

[0067] A2. Bushing; A21. First bushing guide portion; A211. First bushing guide plane; A22. Second bushing guide portion; A221. Second bushing guide plane; A23. Bushing curved surface; A231. First bushing curved surface; A232. Second bushing curved surface; A24. Limiting portion; A25. Groove;

[0068] B. Drum brake assembly;

[0069] B1. Brake drum;

[0070] B2. Brake shoe assembly; B21. Reverse shoe assembly; B22. Forward shoe assembly;

[0071] B3. Actuator;

[0072] B4. Mounting bracket;

[0073] B5. Outer ring;

[0074] B6. Friction plate;

[0075] C1. First rotating shaft assembly; C2. Second rotating shaft assembly;

[0076] Arrow X1. First direction of the first rotating shaft assembly; Arrow K1. Second direction of the first rotating shaft assembly;

[0077] Arrow X2. First direction of the second rotating shaft assembly; Arrow K2. Second direction of the second rotating shaft assembly;

[0078] Arrow F indicates the driving direction of the actuator;

[0079] Arrow f1: Direction of frictional torque of the counter-shoe assembly; Arrow f2: Direction of frictional torque of the clockwise shoe assembly;

[0080] F1. Direction of bushing movement. Detailed Implementation

[0081] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described with reference to the accompanying drawings. In the drawings, the same reference numerals indicate components with the same or similar structures but the same function.

[0082] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0083] Reference Figures 1-6 In a specific embodiment of this application, the drum brake assembly B is used for vehicle braking and includes a brake drum B1, a brake shoe assembly B2, an actuator B3, and a mounting base B4; the shaft assembly A is connected to the brake shoe, and the brake shoe can rotate around the shaft assembly A to move closer to or away from the brake drum B1.

[0084] Among them, brake drum B1 and brake shoe assembly B2 are friction pairs of drum brake assembly B. Brake drum B1 is a rotating element with its cylindrical inner surface as the working surface. Brake shoe assembly B2 is a fixed element. Friction pad B6 is connected to the working surface of brake shoe assembly B2 facing brake drum B1. One end of brake shoe assembly B2 is connected to actuator B3, and the other end is rotatably connected to shaft assembly A. Shaft assembly A is mounted on mounting base B4. When actuator B3 drives brake shoe assembly B2 to move towards brake drum B1, brake shoe assembly B2 can drive friction pad B6 to rotate around shaft assembly A to get close to the working surface of brake drum B1, thereby generating friction and thus generating braking torque.

[0085] Reference Figures 7-13In a specific embodiment of this application, the rotating shaft assembly A includes a spindle A1 and a bushing A2 sleeved on the spindle A1; the bushing A2 includes an outer surface and an inner surface, and the inner surface of the bushing A2 includes a first bushing guide portion A21 and a second bushing guide portion A22. The spindle A1 is fixedly mounted on the mounting base B4, and the surface of the spindle A1 includes a first spindle guide portion A11 and a second spindle guide portion A12. The first bushing guide portion A21 cooperates with the first spindle guide portion A11 to allow the bushing A2 to move relative to the spindle A1 in a first direction, and the second bushing guide portion A22 cooperates with the second spindle guide portion A22. The spindle guide A12 engages with the bushing A2 so that the bushing A2 can move relative to the spindle A1 in a second direction. The outer surface of the bushing A2 includes a circumferential surface. One end of the brake shoe assembly B2 is rotatably connected to the bushing A2, and the brake shoe can rotate relative to the circumferential surface of the outer surface of the bushing A2. The bushing A2 has an initial position relative to the spindle A1. At the initial position, the first bushing guide A21 engages with the first spindle guide A11 and the second bushing guide A22 engages with the second spindle guide A12. Both the first direction and the second direction are in a plane perpendicular to the axial direction of the spindle A1.

[0086] At the initial position, the bushing A2 and the mandrel A1 cannot move relative to each other in the first or second direction due to the mutual engagement between the first bushing guide A21 and the first mandrel guide A11, the second bushing guide A22 and the second mandrel guide A12. Only when the bushing A2 and the mandrel A1 rotate relative to each other, causing the bushing A2 to leave the initial position relative to the mandrel A1, thus disengaging the first bushing guide A21 from the first mandrel guide A11, or the second bushing guide A22 from the second mandrel guide A12, can the bushing A2 and the mandrel A1 move relative to each other in the first or second direction.

[0087] In another specific embodiment of this application, based on the premise that the bushing A2 and the brake shoe can rotate relative to each other, the outer surface of the bushing A2 can be the entire circumferential surface or a partial circumferential surface.

[0088] In another specific embodiment of this application, based on the relative movement of bushing A2 and mandrel A1 in the first direction and the second direction, the first bushing guide A21 and the second bushing guide A22 can be planes, or extrusion grooves or other structures with guiding functions.

[0089] As described above, the spindle A1 can be fixedly mounted on the mounting base B4, and the bushing A2 is sleeved on the spindle A1. The bushing A2 is located between the brake shoe and the spindle A1, and the bushing A2 has two relative movements with respect to both the brake shoe and the spindle A1. First, the bushing A2 can translate relative to the spindle A1 along a first direction, and also translate relative to the spindle A1 along a second direction. The first and second directions are two different directions in a plane perpendicular to the axial direction of the spindle A1. Second, the outer surface of the bushing A2 includes a circumferential surface, and the brake shoe can rotate relative to this circumferential surface, achieving relative rotation between the brake shoe and the bushing A2. Thus, the brake shoe…

[0090] Thus, the brake shoe connected to bushing A2 can have two types of motion: one is a fixed-axis rotation relative to bushing A2, and the other is a translational movement along a first or second direction relative to the spindle A1 with bushing A2, and the fixed-axis rotation and translational movements are independent of each other. Therefore, the rotating shaft assembly A enables the brake shoe to have two degrees of freedom of motion, namely: the brake shoe can move on the plane combining the fixed-axis rotation and the parallel translation, and the movement of the brake shoe can form a planar superposition motion with the cylindrical inner surface of the brake drum B1. This not only allows the brake friction pad B6 to completely superimpose with the cylindrical inner surface of the brake drum B1, so that the friction can be evenly distributed along the cylindrical inner surface of the brake drum B1, but also generates a larger and more stable frictional force by increasing the superposition surface. This can fundamentally solve a series of problems caused by uneven friction in current drum brakes, such as insufficient braking force, wear, lock-up, noise, sideslip, tail-wagging, deviation, drag, uneven wear, and unbalanced force on the drive shaft.

[0091] Reference Figures 1-6In a specific embodiment of this application, the working process of the drum brake assembly B is as follows: the actuator B3 drives the brake shoe assembly B2 to expand outward. While the brake shoe assembly B2 rotates around the fixed axis of the bushing A2, the bushing A2 can move relative to the spindle A1 in the first direction or the second direction according to the direction of the braking torque. As a result, the brake shoe can approach the brake drum B1 along the first direction or the second direction. As a result, the friction plate B6 of the brake shoe assembly B2 can adhere to the brake drum B1 along the first direction or the second direction under the action of the braking force. Since the rotation of the brake shoe assembly B2 and its movement along the first or second direction are independent movements, while the brake shoe assembly B2 drives the friction pad B6 to rotate, the friction pad B6 can completely overlap with the cylindrical inner surface of the brake drum B1 at a certain point in the first or second direction. When the friction pad B6 completely overlaps with the cylindrical inner surface of the brake drum B1, the reaction force will stop the brake shoe assembly B2 in the braking position, keeping the friction pad B6 and the cylindrical inner surface of the brake drum B1 in a completely overlapped position. Due to the complete overlap, the wear of each part of the friction pad B6 is uniform, and because of the complete overlap, the overlap surface is the largest, that is, the friction area is the largest, thus generating the largest and most stable friction force.

[0092] Reference Figure 1 , Figure 3 , Figure 4 , Figure 5 and Figure 6 In a specific embodiment of this application, the brake shoe assembly B2 includes a reverse shoe assembly B21 and a forward shoe assembly B22. The reverse shoe assembly B21 is connected to the first shaft assembly C1, and the forward shoe assembly B22 is connected to the second shaft assembly C2. The first direction of the first shaft assembly C1 extends radially outward from its initial position along the reverse shoe assembly B21. The first direction of the second shaft assembly C2 extends radially outward from its initial position along the forward shoe assembly B22.

[0093] During braking, the frictional torque of the reverse shoe assembly B21 pushes its brake shoe against the brake drum B1, while the frictional torque of the forward shoe assembly B22 pulls its brake shoe away from the brake drum B1.

[0094] Specifically, refer to Figure 1 , Figure 3 , Figure 4 and Figure 5 The diagram shows a counter-clockwise direction as the direction of wheel rotation during normal driving. Brake drum B1 rotates counter-clockwise with the wheel. At this time, actuator B3 drives brake shoe assembly B2 to expand outwards. Reverse shoe assembly B21 is on the left, and forward shoe assembly B22 is on the right. The braking process is as follows:

[0095] Driven by actuator B3, the reverse shoe assembly B21 rotates counterclockwise around the bushing A2 of the first rotating shaft assembly C1. After the reverse shoe assembly B21 rotates counterclockwise and contacts the left side of the brake drum B1, the torque of the brake drum B1 on the brake shoe in the reverse shoe assembly B21 pushes the brake shoe. The bushing A2 of the first rotating shaft assembly C1 can move relative to its spindle A1 in a radially downward and outward direction along its first direction. The distance of movement is related to the magnitude of the braking torque and is independent of the relative rotation between the reverse shoe assembly B21 and the bushing A2. The greater the braking torque, the greater the distance that the bushing A2 moves relative to its spindle A1 in a radially downward and outward direction along its first direction, and vice versa. In this way, the reverse shoe assembly B21 can completely overlap with the cylindrical inner surface on the left side of the brake drum B1. Meanwhile, driven by actuator B3, the follower assembly B22 rotates clockwise around the bushing A2 of the second rotating shaft assembly C2. After the follower assembly B22 rotates clockwise and contacts the right side of the brake drum B1, the torque exerted by the brake drum B1 on the brake shoe in the follower assembly B22 pulls the brake shoe. The bushing A2 of the second rotating shaft assembly C2 can also move relative to its spindle A1 in the upward and outward directions along its second direction. The distance of movement is related to the magnitude of the braking torque and is independent of the relative rotation between the follower assembly B22 and the bushing A2. The greater the braking torque, the greater the distance that the bushing A2 moves relative to its spindle A1 in the upward and outward directions along its second direction, and vice versa. In this way, the follower assembly B22 can completely overlap with the cylindrical inner surface of the right side of the brake drum B1.

[0096] Therefore, during normal braking, the reverse shoe assembly B21 can rotate relative to the bushing A2 of the first shaft assembly C1 and can also move along the first direction of the first shaft assembly C1. The two movements are independent of each other, so that the reverse shoe assembly B21 can completely overlap with the cylindrical inner surface on the left side of the brake drum B1; the forward shoe assembly B22 can rotate relative to the bushing A2 of the second shaft assembly C2 and can also move along the second direction of the second shaft assembly C2. The two movements are independent of each other, so that the forward shoe assembly B22 can completely overlap with the cylindrical inner surface on the right side of the brake drum B1. Therefore, on the one hand, all parts of the reverse shoe assembly B21 and the forward shoe assembly B22 can overlap with the cylindrical inner surface of the brake drum B1, and the force on each part is uniform, so there will be no uneven wear at the upper and lower ends of the friction pad B6; on the other hand, both the reverse shoe assembly B21 and the forward shoe assembly B22 can overlap with the cylindrical inner surface of the brake drum B1, and the force on the reverse shoe assembly B21 and the forward shoe assembly B22 is equal, so there will be no situation where, for example, the reverse shoe assembly B21 is severely worn while the forward shoe assembly B22 is less worn.

[0097] Specifically, refer to Figure 1 and Figure 6The clockwise direction in the attached diagram is specified as the direction of wheel rotation when reversing. The brake drum B1 rotates clockwise with the wheel. The counter-shoe assembly B21 is on the right and the clockwise assembly B22 is on the left. The braking principle is the same as above.

[0098] The terms "clockwise," "counterclockwise," "upper end," "lower end," "left side," and "right side" used in this document to describe direction and location are merely for reference to the accompanying drawings and should not unduly limit the scope of protection of this application.

[0099] Reference Figures 7-13 In a specific embodiment of this application, the first bushing guide portion A21 includes a first bushing guide plane A211 along a first direction; the second bushing guide portion A22 includes a second bushing guide plane A221 along a second direction; the first spindle guide portion A11 includes a first spindle guide plane A111 along a first direction; the second spindle guide portion A12 includes a second spindle guide plane A121 along a second direction; the first bushing guide plane A211 is capable of abutting against the first spindle guide plane A111; the second bushing guide plane A221 is capable of abutting against the second spindle guide plane A121; at the initial position, the first bushing guide plane A211 abuts against the first spindle guide plane A111, and the second bushing guide plane A221 abuts against the second spindle guide plane A121.

[0100] This design limits the first bushing guide A21, the first spindle guide A11, the second bushing guide A22, and the second spindle guide A12 to all being planar, which reduces the difficulty and cost of machining and makes the installation between the bushing A2 and the spindle A1 more convenient and reliable.

[0101] Reference Figures 7-13In a specific embodiment of this application, the first mandrel guide plane A111 is adjacent to the second mandrel guide plane A121. One end of the first mandrel guide plane A111 is connected to one end of the second mandrel guide plane A121 at their intersection. The other end of the first mandrel guide plane A111 is connected to the other end of the second mandrel guide plane A121 through a mandrel curved surface A13. The mandrel curved surface A13 includes a first mandrel curved surface A131 adjacent to the first mandrel guide plane A111 and a second mandrel curved surface A132 adjacent to the second mandrel guide plane A121. The first bushing guide plane A211 is adjacent to the second bushing guide plane A221. One end of the first bushing guide plane A211 is connected to one end of the second bushing guide plane A221 at their intersection. The other end of the first bushing guide plane A211 is connected to the other end of the second bushing guide plane A221 through the bushing surface A23. The bushing surface A23 includes a first bushing surface A231 adjacent to the first bushing guide plane A211 and a second bushing surface A232 adjacent to the second bushing guide plane A221. The bushing A2 moves relative to the spindle A1 in a first direction so that the first bushing surface A231 can abut against the first spindle surface A131. The bushing A2 moves relative to the spindle A1 in a second direction so that the second bushing surface A232 can abut against the second spindle surface A132.

[0102] Thus, the first mandrel guide plane A111 and the second mandrel guide plane A121 are adjacent and connected at their intersection. The other ends of the first mandrel guide plane A111 and the second mandrel guide plane A121 away from their intersection are connected by the mandrel curved surface A13, that is, the other ends of the first mandrel guide plane A111 and the second mandrel guide plane A121 away from their intersection are connected by an arc curved surface. Similarly, the first bushing guide plane A211 and the second bushing guide plane A221 are adjacent and connected at their intersection. The other ends of the first bushing guide plane A211 and the second bushing guide plane A221 away from their intersection are connected by the bushing curved surface A23, that is, the other ends of the first bushing guide plane A211 and the second bushing guide plane A221 away from their intersection are connected by an arc curved surface. Furthermore, when bushing A2 moves relative to spindle A1 in the first direction, the first bushing surface A231 can abut against the first spindle surface A131; when bushing A2 moves relative to spindle A1 in the second direction, the second bushing surface A232 can abut against the second spindle surface A132. This allows bushing A2 and spindle A1 to rotate relative to each other to a certain extent along the arc surface, supporting relative translation between bushing A2 and spindle A1 in the first or second direction.

[0103] Reference Figure 8 and Figure 11In a specific embodiment of this application, the bushing A2 further includes a limiting part A24, where the bushing A2 abuts against the spindle A1. In the circumferential direction of the spindle A1, the limiting part A24 is opposite to the intersection of the first bushing guide plane A211 and the second bushing guide plane A221.

[0104] Thus, in the circumferential direction of the mandrel A1, one side of the first bushing curved surface A231 is connected to the first bushing guide plane A211, and the other side is connected to the limiting part A24; one side of the second bushing curved surface A232 is connected to the second bushing guide plane A221, and the other side is connected to the limiting part A24. The limiting part A24 can prevent the connection between the first bushing curved surface A231 and the second bushing curved surface A232 along the arc surface. The limiting part A24 can restrict the movement of the first mandrel curved surface A131 within the first bushing curved surface A231 and restrict the movement of the second mandrel curved surface A132 within the second bushing curved surface A232, preventing the first bushing curved surface A231 and the second mandrel curved surface A132 from abutting against each other, and also preventing the second bushing curved surface A232 and the first mandrel curved surface A131 from abutting against each other. That is, the limiting part A24 can limit the relative rotation between the bushing A2 and the spindle A1, so that the bushing A2 and the spindle A1 cannot be flipped relative to each other.

[0105] In a specific embodiment of this application, bushing A2 further includes a first bushing A2 auxiliary guide plane, which is connected to the limiting part A24 and extends along a first direction; bushing A2 also includes a second bushing A2 auxiliary guide plane, which is connected to the limiting part A24 and extends along a second direction.

[0106] Thus, the auxiliary guide plane of the first bushing A2 and the auxiliary guide plane of the second bushing A2 can further prevent the bushing A2 from flipping relative to the spindle A1.

[0107] Reference Figure 12 In a specific embodiment of this application, the mandrel A1 includes a sector-shaped shaft, and an included angle is formed between the first mandrel guide portion A11 and the second mandrel guide portion A12, with the included angle pointing toward the axis of the mandrel A1, and the first mandrel guide portion A11 and the second mandrel guide portion A12 are symmetrical with respect to the diameter of the mandrel A1.

[0108] Thus, the first spindle guide A11 and the second spindle guide A12 are symmetrical with respect to the diameter of the spindle A1, making the structure of the spindle A1 symmetrical, which in turn makes the structure of the bushing A2 that mates with the spindle A1 symmetrical, thereby making the overall structure of the rotating shaft assembly A balanced and the force balanced.

[0109] Reference Figure 10In a specific embodiment of this application, the mandrel A1 includes a notched shaft, and an included angle is formed between the first mandrel guide portion A11 and the second mandrel guide portion A12. The included angle is directed away from the axis of the mandrel A1, and the first mandrel guide portion A11 and the second mandrel guide portion A12 are symmetrical with respect to the diameter of the mandrel A1.

[0110] Therefore, the mandrel A1 has a notched shaft, and the notch A16 facilitates the installation and removal of the mandrel A1. At the same time, the first mandrel guide part A11 and the second mandrel guide part A12 are symmetrical with respect to the diameter of the mandrel A1, which makes the structure of the mandrel A1 symmetrical, and in turn makes the structure of the bushing A2 that mates with the mandrel A1 symmetrical, thereby making the overall structure of the rotating shaft assembly A balanced and the force balanced.

[0111] Reference Figure 7 , Figure 9 and Figure 12 In a specific embodiment of this application, the mandrel A1 includes a guide section A14 located in the middle of the mandrel A1 and mounting portions A15 located at both ends of the mandrel A1, and the bushing A2 is sleeved on the guide section A14 of the mandrel A1.

[0112] Thus, bushing A2 is provided in the guide section A14 in the middle of spindle A1. Guide section A14 facilitates the installation and disassembly of bushing A2 and spindle A1. Mounting parts A15 at both ends of spindle A1 facilitate the fixed installation of spindle A1 on mounting base B4.

[0113] Reference Figure 7 , Figure 9 and Figure 12 In a specific embodiment of this application, the mandrel A1 includes at least one mounting guide surface A17, which is located at the end of the mandrel A1 such that the outermost end profile of the mandrel A1 has a reduced diameter.

[0114] Therefore, when the spindle A1 is installed on the mounting base B4, the mounting guide surface A17 can play a guiding role, making the installation more convenient.

[0115] Reference Figure 9 In a specific embodiment of this application, the mandrel A1 has an outer diameter R1, the outermost end profile of the mandrel A1 has a reduced diameter R2, the bushing A2 has a travel length L1 relative to the mandrel A1 in a first direction, and the bushing A2 has a travel length L2 relative to the mandrel A1 in a second direction; R1-R2>L1, and R1-R2>L2.

[0116] Therefore, the travel length L1 of the bushing A2 relative to the spindle A1 in the first direction and the travel length L2 of the bushing A2 relative to the spindle A1 in the second direction are both less than the difference between the outer diameter of the spindle A1 and the diameter of the outermost end, thus limiting the relative movement between the bushing A2 and the spindle A1 in the first and second directions.

[0117] In a specific embodiment of this application, the travel length of the bushing A2 relative to the spindle A1 in the first direction is equal to the travel length of the bushing A2 relative to the spindle A1 in the second direction, i.e., L1 = L2.

[0118] This ensures that the relative movements of bushing A2 and spindle A1 in the first and second directions are symmetrical and the motion between bushing A2 and spindle A1 is balanced, thereby balancing the motion of the brake shoe.

[0119] Reference Figure 13 In a specific embodiment of this application, the drum brake assembly B further includes an outer ring B5, which is fixedly connected to the brake shoe assembly B2 and rotatably connected to the bushing A2.

[0120] Thus, the outer ring B5 is located between the bushing A2 and the brake shoe assembly B2. The outer ring B5 is fixedly connected to the brake shoe assembly B2. The outer ring B5 can be sleeved on the bushing A2 to achieve a rotatable connection between the outer ring B5 and the bushing A2. When the brake shoe assembly B2 and the bushing A2 rotate relative to each other, the outer ring B5 can bear most of the friction, thereby protecting the connection between the brake shoe assembly B2 and the bushing A2, thus extending the service life of the brake shoe assembly B2 and the bushing A2. The outer ring B5 is a detachable and replaceable component with low replacement cost.

[0121] Reference Figure 4 In a specific embodiment of this application, the second direction of the first rotating shaft assembly C1 has an angle θ1 with the first direction of the first rotating shaft assembly C1; the second direction of the second rotating shaft assembly C2 has an angle θ2 with the first direction of the second rotating shaft assembly C2; 80°<θ1<160°, 80°<θ2<160°.

[0122] The first direction affects the normal driving braking force, and the second direction affects the reversing braking force. The angle between the first and second directions determines the balance of braking force of the reverse shoe assembly B21 and the forward shoe assembly B22 in driving and reversing, respectively. Experiments have shown that the range of 80°<θ1<160° and 80°<θ2<160° is the most stable and appropriate.

[0123] Reference Figure 5In a specific embodiment of this application, brake drum B1 has a center O1, first shaft assembly C1 has a center D1, and second shaft assembly C2 has a center D2. The line connecting the center O1 of brake drum B1 to the center D1 of first shaft assembly C1 and the center D2 of second shaft assembly C2 has a distance H. The distance L between the center D1 of first shaft assembly C1 and the center D2 of second shaft assembly C2 is also significant. Bushing A2 has an outer diameter R, and the first direction forms an angle α with the horizontal plane, where: 2H / (L+2R) <Tanα<2H / L。

[0124] Therefore, the distance between the intersection of the first spindle guide A11 and the second spindle guide A12 of the first rotating shaft assembly C1 and the intersection of the first spindle guide A11 and the second spindle guide A12 of the second rotating shaft assembly C2 is greater than L and less than L+2R.

[0125] Reference Figure 4 In a specific embodiment of this application, the angle θ1 between the second direction of the first rotating shaft assembly C1 and the first direction of the first rotating shaft assembly C1, and the angle θ2 between the second direction of the second rotating shaft assembly C2 and the first direction of the second rotating shaft assembly C2, satisfy: θ1=θ2; the angle α1 between the first direction of the first rotating shaft assembly C1 and the horizontal plane, and the angle α2 between the first direction of the second rotating shaft assembly C2 and the horizontal plane, satisfy: α1=α2.

[0126] Therefore, with the diameter of the brake drum B1 as the axis of symmetry, the first direction of the first rotating shaft assembly C1 is symmetrical with the first direction of the second rotating shaft assembly C2, and the second direction of the second rotating shaft assembly C2 is symmetrical with the second rotating shaft assembly C2. That is, the installation positions and installation angles of the first rotating shaft assembly C1 and the second rotating shaft assembly C2 are symmetrical with each other, so that the relative movements of the reverse shoe assembly B21 and the forward shoe assembly B22 are symmetrical with each other, and the braking process of the drum brake assembly B is balanced and stable.

[0127] In a specific embodiment of this application, the angle α1 between the first direction of the first rotating shaft assembly C1 and the horizontal plane and the angle α2 between the first direction of the second rotating shaft assembly C2 and the horizontal plane satisfy 68°<α1<82° and 68°<α2<82°.

[0128] If the angle between the first direction of the first rotating shaft assembly C1 and the horizontal plane is too small, the angle between the first direction and the second direction of the first rotating shaft assembly C1 will be too sharp, resulting in greater wear on the front end of the brake shoe assembly B2. If the angle between the first direction of the first rotating shaft assembly C1 and the horizontal plane is too large, the angle between the second direction and the second opposite direction of the first rotating shaft assembly C1 will be too rounded, resulting in excessive braking force and excessive sensitivity. The same applies to the second rotating shaft assembly C2. Therefore, the angle between the first direction and the horizontal plane affects the movement path of the brake shoe assembly B2 during the overlapping process with the brake drum B1. The overlapping movement path affects the braking force and the wear on the front end of the brake shoe assembly B2. Comprehensive experiments have shown that the numerical range of 68° < α1 < 82° and 68° < α2 < 82° is the most balanced.

[0129] In a specific embodiment of this application, the inner surface of the brake drum B1 and the outer surface of the friction pad B6 of the brake shoe assembly B2 have an initial distance D; the bushing A2 moves relative to the spindle A1 in a first direction with a stroke length L1, and the bushing A2 moves relative to the spindle A1 in a second direction with a stroke length L2; wherein, L1≥D, L2≥D.

[0130] Thus, when bushing A2 moves relative to spindle A1 in the first direction, the movement distance of brake shoe assembly B2 in the first direction is sufficient for the friction plate B6 of brake shoe assembly B2 to overlap with the inner surface of brake drum B1. When bushing A2 moves relative to spindle A1 in the second direction, the movement distance of brake shoe assembly B2 in the second direction is sufficient for the friction plate B6 of brake shoe assembly B2 to overlap with the inner surface of brake drum B1.

[0131] In another specific embodiment, a groove A25 is provided at the intersection of the first bushing guide portion A21, the second bushing guide portion A22, and / or the intersection of the first bushing guide portion A21 and the second bushing guide portion A22, and the groove A25 connects the two ends of the bushing A2. This facilitates the storage of lubricating oil or grease between the bushing A2 and the spindle A1, improving lubrication performance.

[0132] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0133] The above are merely embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A rotating shaft assembly connected to a brake shoe, the brake shoe being rotatable about the rotating shaft assembly to move closer to or further away from a brake drum, characterized in that, The rotating shaft assembly includes a spindle and a bushing fitted onto the spindle; The bushing includes an outer surface and an inner surface. The inner surface of the bushing includes a first bushing guide portion and a second bushing guide portion. The surface of the spindle includes a first spindle guide portion and a second spindle guide portion. The first bushing guide portion cooperates with the first spindle guide portion to enable the bushing to move relative to the spindle in a first direction. The second bushing guide portion cooperates with the second spindle guide portion to enable the bushing to move relative to the spindle in a second direction. The outer surface of the bushing includes a circumferential surface. The brake shoe is rotatable relative to the circumferential surface of the outer surface of the bushing. The bushing has an initial position relative to the mandrel. At the initial position, the first bushing guide portion cooperates with the first mandrel guide portion and the second bushing guide portion cooperates with the second mandrel guide portion. The mutual cooperation between the first bushing guide portion and the first mandrel guide portion, the second bushing guide portion and the second mandrel guide portion forms a limit, and the bushing and the mandrel cannot move relative to each other in a first direction or a second direction. Both the first direction and the second direction are located in a plane perpendicular to the axis of the mandrel.

2. The rotating shaft assembly as described in claim 1, characterized in that, The first bushing guide includes a first bushing guide plane along the first direction; The second bushing guide includes a second bushing guide plane along the second direction; The first mandrel guide portion includes a first mandrel guide plane along the first direction; The second mandrel guide portion includes a second mandrel guide plane along the second direction; The first bushing guide plane can abut against the first mandrel guide plane; The second bushing guide plane can abut against the second mandrel guide plane; At the initial position, the first bushing guide plane abuts against the first mandrel guide plane, and the second bushing guide plane abuts against the second mandrel guide plane.

3. The rotating shaft assembly as described in claim 2, characterized in that, The first mandrel guide plane is adjacent to the second mandrel guide plane. One end of the first mandrel guide plane and one end of the second mandrel guide plane are connected at their intersection. The other end of the first mandrel guide plane and the other end of the second mandrel guide plane are connected through a mandrel curved surface. The mandrel curved surface includes a first mandrel curved surface adjacent to the first mandrel guide plane and a second mandrel curved surface adjacent to the second mandrel guide plane. The first bushing guide plane is adjacent to the second bushing guide plane. One end of the first bushing guide plane and one end of the second bushing guide plane are connected at their intersection. The other end of the first bushing guide plane and the other end of the second bushing guide plane are connected through a bushing curved surface. The bushing curved surface includes a first bushing curved surface adjacent to the first bushing guide plane and a second bushing curved surface adjacent to the second bushing guide plane. The bushing is moved relative to the mandrel in a first direction so that the first bushing surface can abut against the first mandrel surface. The bushing moves relative to the mandrel in a second direction so that the curved surface of the second bushing can abut against the curved surface of the second mandrel.

4. The rotating shaft assembly as described in claim 2, characterized in that, The bushing also includes a limiting part, which abuts against the mandrel. In the circumferential direction of the mandrel, the limiting part is opposite to the intersection of the first bushing guide plane and the second bushing guide plane.

5. The rotating shaft assembly as described in claim 4, characterized in that, The bushing further includes a first bushing auxiliary guide plane, which is connected to the limiting portion and extends along the first direction; The bushing also includes a second bushing auxiliary guide plane, which is connected to the limiting portion and extends along the second direction.

6. The rotating shaft assembly as claimed in claim 1, characterized in that, The mandrel includes a sector-shaped shaft, with an included angle formed between the first mandrel guide portion and the second mandrel guide portion, the included angle being directed toward the axis of the mandrel, and the first mandrel guide portion and the second mandrel guide portion being symmetrical with respect to the diameter of the mandrel.

7. The rotating shaft assembly as claimed in claim 1, characterized in that, The mandrel includes a notched shaft, and an angle is formed between the first mandrel guide portion and the second mandrel guide portion, the angle being directed away from the axis of the mandrel, and the first mandrel guide portion and the second mandrel guide portion are symmetrical with respect to the diameter of the mandrel.

8. The rotating shaft assembly as described in claim 6 or 7, characterized in that, The mandrel includes a guide section located in the middle of the mandrel and mounting portions located at both ends of the mandrel, and the bushing is sleeved on the guide section of the mandrel.

9. The rotating shaft assembly as claimed in claim 8, characterized in that, The mandrel includes at least one mounting guide surface located at the end of the mandrel such that the outermost end profile of the mandrel has a reduced diameter.

10. The rotating shaft assembly as claimed in claim 9, characterized in that, The mandrel has an outer diameter R1, the outermost end profile of the mandrel has a reduced diameter R2, the bushing has a travel length L1 relative to the movement of the mandrel in the first direction, and the bushing has a travel length L2 relative to the movement of the mandrel in the second direction. R1-R2>L1, and R1-R2>L2.

11. The rotating shaft assembly as claimed in claim 10, characterized in that, The travel length of the bushing relative to the spindle in the first direction is equal to the travel length of the bushing relative to the spindle in the second direction, i.e., L1=L2.

12. A drum brake assembly, comprising a brake drum, a brake shoe assembly, an actuator, and a mounting base, wherein the actuator is brakely connected to one end of the brake shoe assembly to drive the brake shoe assembly toward the brake drum, characterized in that, Includes the shaft assembly as described in claims 1-11, wherein the spindle is fixedly mounted on the mounting base, and the other end of the brake shoe assembly is rotatably connected to the bushing so that the brake shoe assembly can rotate relative to the bushing and can move toward the brake drum along the first direction or the second direction with the bushing.

13. The drum brake assembly as claimed in claim 12, characterized in that, It also includes an outer ring, which is fixedly connected to the brake shoe assembly and rotatably connected to the bushing.

14. The drum brake assembly as claimed in claim 12, characterized in that, The brake shoe assembly includes a reverse shoe assembly and a forward shoe assembly. The reverse shoe assembly is connected to the first rotating shaft assembly, and the forward shoe assembly is connected to the second rotating shaft assembly. The first direction of the first rotating shaft assembly extends radially outward from the initial position of the first rotating shaft assembly; The first direction of the second shaft assembly extends radially outward from the initial position of the second shaft assembly along the pawl assembly.

15. The drum brake assembly as claimed in claim 14, characterized in that, The second direction of the first rotating shaft assembly has an angle θ1 with the first direction of the first rotating shaft assembly; The second direction of the second rotating shaft assembly has an angle θ2 with the first direction of the second rotating shaft assembly; 80 <θ1<160 、80 <θ2<160 。 16. The drum brake assembly as claimed in claim 15, characterized in that, The brake drum has a center O1, the first shaft assembly has a center D1, and the second shaft assembly has a center D2. A distance H is provided between the center O1 of the brake drum and the lines connecting the centers D1 and D2 of the first and second shaft assemblies. A distance L is provided between the centers D1 and D2 of the first and second shaft assemblies. The bushing has an outer diameter R. The first direction forms an angle α with the horizontal plane, wherein: 2H / (L+2R) <Tanα<2H / L。 17. The drum brake assembly as claimed in claim 16, characterized in that, The angle θ1 between the second direction of the first rotating shaft assembly and the first direction of the first rotating shaft assembly and the angle θ2 between the second direction of the second rotating shaft assembly and the first direction of the second rotating shaft assembly satisfy: θ1=θ2; The angle α1 between the first direction of the first rotating shaft assembly and the horizontal plane and the angle α2 between the first direction of the second rotating shaft assembly and the horizontal plane satisfy: α1=α2.

18. The drum brake assembly as claimed in claim 16, characterized in that, The angle α1 between the first direction of the first rotating shaft assembly and the horizontal plane and the angle α2 between the first direction of the second rotating shaft assembly and the horizontal plane satisfy 68°. <α1<82 And 68 <α2<82 .

19. The drum brake assembly as claimed in claim 12, characterized in that, The inner surface of the brake drum and the outer surface of the friction pad of the brake shoe assembly have an initial distance D; The bushing has a travel length L1 relative to the spindle in the first direction, and the bushing has a travel length L2 relative to the spindle in the second direction; Where L1≥D, L2≥D.

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