Drum brake, wheel and vehicle

Abstract

The drum brake comprises a brake drum, a shoe block assembly and a one-way ratchet wheel assembly, the shoe block assembly comprises a transmission shaft, a shoe block and a first elastic piece, the transmission shaft is connected with the brake drum in a pivoted mode around the axis of the transmission shaft, and the transmission shaft is connected with the shoe block. The transmission shaft rotates around the axis of the transmission shaft in the first direction so as to drive the shoe block to move from the initial position to the brake position abutting against the brake drum, the first elastic piece presses the shoe block towards the initial position, the one-way ratchet wheel assembly comprises a crank, a ratchet wheel and a pawl, the ratchet wheel is coaxially connected with the transmission shaft, and the crank is pivotally connected with the ratchet wheel around the axis of the ratchet wheel. The crank is suitable for driving the ratchet wheel to synchronously rotate in the first direction through the pawl. The drum brake provided by the utility model has the advantages of high convenience in extension compensation of the brake cable, long service life of the shoe block and low use cost.

Description

Technical Field

[0001] This utility model relates to the field of two-wheeled vehicle technology, specifically to a drum brake, a wheel, and a vehicle. Background Technology

[0002] Braking mechanisms for two-wheeled vehicles such as bicycles and electric bikes are typically divided into disc brakes and drum brakes. However, in related technologies, the brake cable of drum brakes is prone to fatigue and elongation due to long-term stress, requiring frequent adjustment of the brake cable nut to adjust the tension. If not adjusted in time, it can lead to excessive braking travel, seriously affecting braking safety and increasing the user's maintenance burden. At the same time, the drum brake shoes gradually wear down over time due to friction. When one side of the shoe wears down to 0.6mm, the adjustable margin of the brake cable is completely exhausted, and it cannot be adjusted further by conventional methods. The only solution is to replace the drum brake, resulting in increased operating costs and wasted resources. Utility Model Content

[0003] This utility model aims to at least partially solve one of the technical problems in the related art.

[0004] Therefore, embodiments of this utility model propose a drum brake, which has the advantages of high convenience in compensating for brake cable elongation, long service life of brake shoes, low operating cost, and fast adjustment speed.

[0005] An embodiment of this utility model also proposes a wheel and a vehicle.

[0006] The drum brake of this utility model embodiment includes a brake drum, a shoe block assembly, and a one-way ratchet assembly. The shoe block assembly includes a drive shaft, a shoe block, and a first elastic element. The drive shaft is pivotally connected to the brake drum about its axis and is connected to the shoe block. The drive shaft rotates about its axis in a first direction to drive the shoe block from an initial position toward a braking position that abuts against the brake drum. The first elastic element presses the shoe block toward the initial position. The one-way ratchet assembly includes a crank, a ratchet, and a pawl. The ratchet is coaxially connected to the drive shaft. The crank is pivotally connected to the ratchet about the axis of the ratchet. The pawl is disposed on the crank and engages with the ratchet. The crank is adapted to drive the ratchet to rotate synchronously in the first direction through the pawl.

[0007] According to an embodiment of the present invention, a drum brake is provided with a pawl that engages with a ratchet. When the crank rotates in a first direction, the pawl and ratchet lock. When braking is required, the brake cable pulls the crank to rotate in the first direction, causing the drive shaft to rotate synchronously. The drive shaft then moves the brake shoe from its initial position to a braking position where it contacts the brake drum. Braking is achieved through the friction between the brake shoe and the brake drum. At this point, the tension in the brake cable is released, and the brake shoe moves back to its initial position under the action of a first elastic element. This causes the drive shaft and crank to rotate in a second direction opposite to the first direction, achieving a reset operation.

[0008] When the brake cable elongates beyond a set value due to fatigue, the crank will rotate at a slightly larger angle during the reset operation than during the previous braking operation (which is also the rotation angle of the drive shaft during the reset operation). This allows the pawl to automatically jump to the adjacent tooth slot. As a result, during the next braking operation, the drive shaft can still rotate at a predetermined angle under the pull of the brake cable, ensuring stable shoe travel and maintaining the braking effect. The elongation of the brake cable does not require manual compensation, making compensation convenient and quick.

[0009] Furthermore, when the brake shoes wear out, simply press down the brake lever without pressing it to its maximum travel. Pull the crank and drive shaft synchronously in the first direction through the brake cable. At this time, the brake shoes are between the initial position and the braking position. Then, rotate the drive shaft in the first direction (at this time, the pawl is disengaged and the crank does not turn) until the brake shoes come into contact with the brake drum. Then release the brake lever to complete the adjustment. This ensures that the brake shoes have a greater travel during the next braking operation, effectively compensating for the wear of the brake shoes. The braking function of the drum brake can be guaranteed without replacing the brake shoes. The brake shoes have a long service life and low operating cost.

[0010] In some embodiments, the pawl is movably connected to the crank, and the one-way ratchet assembly further includes a second elastic element connecting the pawl and the crank, the second elastic element pressing the pawl toward the ratchet.

[0011] In some embodiments, the crank is provided with a mounting hole, the ratchet is clearance-fitted into the mounting hole, the inner wall of the mounting hole is provided with a first guide hole, the extension direction of the first guide hole is orthogonal to the axial direction of the ratchet, and the pawl is slidably fitted into the first guide hole;

[0012] The first guide hole has a first limiting surface at one end away from the mounting hole. The pawl has a second limiting surface opposite to the first limiting surface along the extension direction of the first guide hole. The second elastic element includes a compression spring, which is located in the first guide hole and sandwiched between the first limiting surface and the second limiting surface.

[0013] In some embodiments, the crank is provided with a second guide hole extending from its outer wall surface to the first limiting surface, and the extension direction of the second guide hole is consistent with the extension direction of the first guide hole;

[0014] The pawl includes a first guide segment and a second guide segment connected together. The first guide segment is slidably fitted into the first guide hole, and the second guide segment is slidably fitted into the second guide hole. A portion of the second guide segment protrudes from the outer wall surface of the crank.

[0015] In some embodiments, the outer contour of the cross-section of at least one of the first guide hole and the second guide hole is not circular.

[0016] In some embodiments, the inner wall of the mounting hole is provided with a first annular groove, the outer peripheral surface of the ratchet is provided with a second annular groove, and the drum brake further includes a retaining ring disposed in the first annular groove and the second annular groove.

[0017] In some embodiments, the mounting hole includes a first hole segment and a second hole segment arranged along its axial direction, the diameter of the first hole segment being smaller than the diameter of the second hole segment, and the first annular groove being disposed on the inner wall surface of the second hole segment.

[0018] The ratchet includes a first shaft segment, a toothed segment, and a second shaft segment connected sequentially along its axial direction. The diameter of the first shaft segment, the tip circle diameter of the toothed segment, and the diameter of the second shaft segment increase sequentially. A second annular groove is provided on the outer circumferential surface of the second shaft segment. The first shaft segment is clearance-fitted into the first hole segment, and the toothed segment and the second shaft segment are clearance-fitted into the second hole segment. The gap between the first shaft segment and the first hole segment is smaller than the gap between the toothed segment and the second hole segment.

[0019] In some embodiments, the drive shaft includes a drive section, an intermediate section, and a threaded section connected sequentially along its axial direction. The drive section is drive-connected to the shoe block. The drum brake also includes a reverse-thread nut, which is threaded to the drive shaft and located on the side of the crank away from the shoe block. The ratchet is sleeved on the intermediate section and sandwiched between the drive section and the reverse-thread nut.

[0020] In some embodiments, the inner hole of the ratchet is a spline hole, the outer contour of the cross-section of the middle section is not circular, and at least a portion of the middle section is disposed in at least one keyway of the spline hole.

[0021] In some embodiments, the cross-sectional outer contour of the transmission section is rectangular, the number of the shoe blocks is two, the first ends of the two shoe blocks are pivotally connected, and the second ends of the two shoe blocks are respectively located on opposite sides of the transmission section along its thickness direction;

[0022] The first elastic element includes a tension spring connected between the two shoes.

[0023] The wheel according to an embodiment of the present invention includes a drum brake as described in any of the above embodiments.

[0024] The technical advantages of the wheel according to the present invention are the same as those of the drum brake in the above embodiments, and will not be repeated here.

[0025] The vehicle according to an embodiment of the present invention includes wheels as described in the above embodiments.

[0026] The technical advantages of the vehicle according to this utility model embodiment are the same as the technical advantages of the wheel described in the above embodiment, and will not be repeated here. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a drum brake according to an embodiment of the present utility model.

[0028] Figure 2 This is an exploded view of the drum brake according to an embodiment of the present utility model.

[0029] Figure 3 This is a cross-sectional view of the one-way ratchet assembly in a drum brake according to an embodiment of the present invention.

[0030] Figure 4 This is another cross-sectional view of the one-way ratchet assembly in the drum brake according to an embodiment of the present utility model.

[0031] Figure label:

[0032] 1. Drive shaft; 11. Drive section; 12. Intermediate section; 13. Threaded section; 2. Shoe block; 3. Tension spring; 4. Crank; 41. First guide hole; 42. Second guide hole; 43. First limiting surface; 5. Ratchet; 51. First shaft section; 52. Toothed section; 53. Second shaft section; 6. Pawl; 61. First guide section; 611. Second limiting surface; 62. Second guide section; 7. Retaining ring; 8. Housing; 9. Reverse thread nut; 10. Compression spring. Detailed Implementation

[0033] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0034] The following is combined Figures 1-4 Describes a drum brake according to an embodiment of the present invention.

[0035] The drum brake of this embodiment includes a brake drum, a shoe block assembly, and a one-way ratchet assembly. The shoe block assembly includes a drive shaft 1, a shoe block 2, and a first elastic element. The drive shaft 1 is pivotally connected to the brake drum around its axis. The drive shaft 1 is connected to the shoe block 2, and the drive shaft 1 rotates around its axis in a first direction to move the shoe block 2 from an initial position toward a braking position that abuts against the brake drum. The first elastic element presses the shoe block 2 toward the initial position. The one-way ratchet assembly includes a crank 4, a ratchet 5, and a pawl 6. The ratchet 5 is coaxially connected to the drive shaft 1. The crank 4 is pivotally connected to the ratchet 5 around the axis of the ratchet 5. The pawl 6 is disposed on the crank 4 and engages with the ratchet 5. The crank 4 is adapted to drive the ratchet 5 to rotate synchronously in the first direction via the pawl 6.

[0036] According to the drum brake of this utility model embodiment, a pawl 6 is engaged with a ratchet 5. When the crank 4 rotates in the first direction, the pawl 6 and ratchet 5 are locked. When braking is required, the brake cable pulls the crank 4 to rotate in the first direction, thereby driving the drive shaft 1 to rotate synchronously. The drive shaft 1 then drives the shoe block 2 to move from its initial position to the braking position where it abuts against the brake drum. The braking operation is achieved through the friction between the shoe block 2 and the brake drum. At this time, the tension on the brake cable is released, and the shoe block 2 moves back to its initial position under the action of the first elastic element, thereby driving the drive shaft 1 and the crank 4 to rotate in the second direction opposite to the first direction, thus achieving a reset operation.

[0037] When the brake cable elongates beyond a set value due to fatigue, the crank 4 will rotate at a slightly larger angle during the reset operation than during the previous braking operation (which is also the rotation angle of the drive shaft 1 during the reset operation). This allows the pawl 6 to automatically jump to the adjacent tooth slot. As a result, during the next braking operation, the drive shaft 1 can still rotate at a predetermined angle under the pull of the brake cable, ensuring the stable stroke of the shoe 2 and maintaining the braking effect. The elongation of the brake cable does not require manual compensation, making compensation convenient and quick.

[0038] Furthermore, when shoe 2 becomes worn, simply press down the brake lever without pressing it to its maximum travel, and pull the crank 4 and drive shaft 1 synchronously in the first direction via the brake cable. At this time, shoe 2 is located between the initial position and the braking position. Then, rotate drive shaft 1 in the first direction (at this time, pawl 6 is disengaged, and crank 4 does not rotate) until shoe 2 comes into contact with the brake drum. Then release the brake lever to complete the adjustment, ensuring that shoe 2 has a greater travel during the next braking operation, effectively compensating for the wear of shoe 2. The braking function of the drum brake can be guaranteed without replacing shoe 2. Shoe 2 has a long service life and low operating cost.

[0039] It should be noted that during the wear compensation operation of shoe block 2, the drive shaft 1 can be rotated in the first direction by directly applying a tool to the drive shaft 1, or the ratchet 5 can be rotated in the first direction by the tool, thereby rotating the drive shaft 1 in the first direction. Alternatively, other structures coaxially connected to the drive shaft 1 can be rotated by the tool, thereby rotating the drive shaft 1 in the first direction. The brake drum of the drum brake is connected to the wheel hub. The drum brake also includes a housing, which is suitable for separating shoe block 2 and the first elastic element from the outside world, effectively ensuring its braking reliability. At the same time, the ratchet 5 can be provided with 120 teeth, each tooth corresponding to 3°. Whenever the brake cable elongates to 0.8mm due to fatigue, during the shoe block 2 reset process, the pawl 6 automatically jumps to the next tooth of the ratchet 5 under the combined action of the inertial force of the crank 4, the elastic force of the first elastic element, and the slack of the brake cable, ensuring stable stroke and consistent braking feel during subsequent braking operations of shoe block 2. In addition, the first direction is counterclockwise, and the second direction is clockwise.

[0040] In some embodiments, the pawl 6 is movably connected to the crank 4, and the one-way ratchet assembly further includes a second elastic element that connects the pawl 6 and the crank 4, and the second elastic element presses the pawl 6 toward the ratchet 5.

[0041] That is, the pawl 6 is engaged with the ratchet 5 under the pressure of the second elastic element. Compared with the method where the pawl 6 is fixedly connected to the crank 4 and engages with the ratchet 5 by its elasticity, the pressure of the second elastic element on the pawl 6 is more reliable, and thus the compensation for the elongation of the brake cable and the compensation for the wear of the shoe block 2 are more reliable.

[0042] For example, the pawl 6 is slidably connected to the crank 4, or the pawl 6 is pivotally connected to the crank 4.

[0043] In some embodiments, the crank 4 is provided with a mounting hole, the ratchet 5 is clearance-fitted into the mounting hole, the inner wall of the mounting hole is provided with a first guide hole 41, the extension direction of the first guide hole 41 is orthogonal to the axial direction of the ratchet 5, and the pawl 6 is slidably fitted into the first guide hole 41. A first limiting surface 43 is formed at the end of the first guide hole 41 away from the mounting hole, and the pawl 6 is provided with a second limiting surface 611 opposite to the first limiting surface 43 along the extension direction of the first guide hole 41. The second elastic element includes a compression spring 10, which is located in the first guide hole 41 and sandwiched between the first limiting surface 43 and the second limiting surface 611.

[0044] That is, under the pressure of the compression spring 10, the pawl 6 engages with the ratchet 5, and the pawl 6 moves linearly relative to the crank 4, ensuring that the different teeth of the pawl 6 and the ratchet 5 engage conveniently and quickly. Moreover, the teeth on the pawl 6 are basically hidden in the first guide hole 41, effectively preventing them from being exposed and affecting the reliability of engagement with the ratchet 5 due to dust accumulation.

[0045] For example, such as Figure 3As shown, the extension direction of the first guide hole 41 is generally consistent with the extension direction of the crank 4. The side of the pawl 6 facing the mounting hole is a circumferential surface co-centered with the mounting hole. Multiple teeth are arranged along the axial direction of the mounting hole. The pawl 6 engages with the ratchet 5 through the multiple teeth to ensure that the pawl 6 and the ratchet 5 are reliably locked.

[0046] In some embodiments, the crank 4 is provided with a second guide hole 42 extending from its outer wall surface to the first limiting surface 43, and the extension direction of the second guide hole 42 is consistent with the extension direction of the first guide hole 41. The pawl 6 includes a first guide segment 61 and a second guide segment 62 connected together. The first guide segment 61 is slidably engaged with the first guide hole 41, and the second guide segment 62 is slidably engaged with the second guide hole 42. A portion of the second guide segment 62 protrudes from the outer wall surface of the crank 4.

[0047] By having a portion of the second guide section 62 protrude from the outer wall of the crank 4, during the shoe block 2 wear compensation operation, the drive shaft 1 can be rotated in the first direction first (e.g., a portion of the drive shaft 1 is exposed, and a tool is used to rotate the exposed portion to drive the drive shaft 1; or a standard part such as a reverse-thread nut 9 is connected to the exposed portion of the drive shaft 1, and a wrench is used to rotate the reverse-thread nut 9 to drive the drive shaft 1 to rotate), while keeping the crank 4 stationary until the shoe block 2 comes into contact with the brake drum. Then, the pawl 6 is pulled by the end of the second guide section 62 to disengage it from the ratchet 5. A fixed-stroke fixture is then used to press down the brake lever (without pressing it to the maximum stroke), causing the brake cable to rotate the crank 4 in the first direction. Finally, the second guide section 62 is released, completing the adjustment. This makes the shoe block 2 wear compensation method more convenient and flexible.

[0048] For example, such as Figure 2 and Figure 3 As shown, the portion of the second guide section 62 exposed on the outer wall of the crank 4 may have a through hole, through which a pull rope can be threaded, making it easier to pull the pawl 6 away from the ratchet 5. The compression spring 10 inside the first guide hole is fitted onto the second guide section 62, thereby effectively preventing the compression spring 10 from bending radially during extension and retraction, and making its pressure on the pawl 6 more reliable.

[0049] In some embodiments, the outer contour of the cross-section of at least one of the first guide hole 41 and the second guide hole 42 is not circular.

[0050] This effectively ensures the relative fixation of the pawl 6 and the crank 4 in the circumferential direction of the first guide hole 41, and the meshing reliability of the pawl 6 and the ratchet 5 is higher.

[0051] For example, such as Figure 2As shown, the outer contour of the cross-section of the first guide segment 61 of the pawl 6 matches the outer contour of the cross-section of the first guide hole 41 and is square, and the outer contour of the cross-section of the second guide segment 62 matches the outer contour of the cross-section of the second guide hole 42 and is circular.

[0052] In some embodiments, the inner wall of the mounting hole is provided with a first annular groove, the outer peripheral surface of the ratchet 5 is provided with a second annular groove, and the drum brake also includes a retaining ring 7, which is disposed in the first annular groove and the second annular groove.

[0053] The setting of the retaining ring 7 ensures that the ratchet 5 and the crank 4 are relatively fixed in the axial direction of the mounting hole, effectively preventing the crank 4 from loosening relative to the ratchet 5 and the drive shaft 1 along the axial direction of the mounting hole, and making the pivot reliability of the crank 4 and the ratchet 5 higher.

[0054] For example, such as Figure 2 and Figure 4 As shown, the retaining ring 7 is a C-type spring retaining ring 7.

[0055] In some embodiments, such as Figure 4 As shown, the mounting hole includes a first hole segment and a second hole segment arranged along its axial direction. The diameter of the first hole segment is smaller than the diameter of the second hole segment. A first annular groove is provided on the inner wall surface of the second hole segment. The ratchet 5 includes a first shaft segment 51, a tooth segment 52, and a second shaft segment 53 connected sequentially along its axial direction. The diameter of the first shaft segment 51, the tooth tip circle diameter of the tooth segment 52, and the diameter of the second shaft segment 53 increase sequentially. A second annular groove is provided on the outer circumferential surface of the second shaft segment 53. The first shaft segment 51 is clearance-fitted into the first hole segment, and the tooth segment 52 and the second shaft segment 53 are clearance-fitted into the second hole segment. The clearance between the first shaft segment 51 and the first hole segment is smaller than the clearance between the tooth segment 52 and the second hole segment.

[0056] By setting the gaps between the first shaft segment 51 and the first bore segment, and the gaps between the second shaft segment 53 and the second bore segment to be as small as possible, the rotational stability of the crank 4 relative to the ratchet 5 is ensured to be higher. Furthermore, external dust is effectively prevented from entering the second bore segment and adhering to and clogging the tooth grooves on the ratchet 5 and pawl 6, thus ensuring the reliable meshing of the ratchet 5 and pawl 6. Conversely, by setting the gap between the tooth segment 52 and the second bore segment to be as large as possible, contact and collision with the crank 4 are effectively prevented from causing wear or deformation of the teeth of the tooth segment 52, further ensuring the reliable meshing of the ratchet 5 and pawl 6.

[0057] For example, such as Figure 4 As shown, the diameter of the first shaft segment 51 is smaller than the root circle diameter of the tooth segment 52, and the root circle diameter of the tooth segment 52 is smaller than the diameter of the second shaft segment 53.

[0058] In some embodiments, such as Figure 1 and Figure 2As shown, the drive shaft 1 includes a drive section 11, an intermediate section 12, and a threaded section 13 connected sequentially along its axial direction. The drive section 11 is connected to the shoe block 2. The drum brake also includes a reverse-threaded nut 9, which is threadedly connected to the threaded section 13 and located on the side of the crank 4 away from the shoe block 2. The ratchet 5 is sleeved on the intermediate section 12 and sandwiched between the drive section 11 and the reverse-threaded nut 9. That is, the reverse-threaded nut 9 presses against the end face of the ratchet 5 away from the shoe block 2.

[0059] At this point, simply fitting the ratchet 5 onto the intermediate section 12 and threading the reverse-threaded nut 9 onto the threaded section 13 achieves coaxial connection between the ratchet 5 and the drive shaft 1, making the connection convenient and reliable. Furthermore, the exposed reverse-threaded nut 9 at this point makes it easier to use tools such as wrenches to apply force to the nut 9 to rotate the drive shaft 1 in the first direction (counterclockwise), further enhancing the convenience of wear compensation operations for the shoe block 2.

[0060] For example, such as Figure 2 and Figure 3 As shown, the inner hole of the ratchet 5 is a spline hole. If it is a 12-spline hole, the outer contour of the cross-section of the middle section 12 is not circular. If it is a square hole, at least a portion of the middle section 12 is disposed in at least one keyway of the spline hole. Thus, when the ratchet 5 is fitted onto the middle section 12, the relative fixation of the two in the circumferential direction of the ratchet 5 is ensured. At this time, the reverse-threaded nut 9 only needs to ensure the relative fixation of the ratchet 5 and the drive shaft 1 in their axial direction, and the coaxial connection between the ratchet 5 and the drive shaft 1 is more reliable.

[0061] In some embodiments, such as Figure 2 As shown, the cross-sectional outline of the transmission section 11 is rectangular, and there are two shoe blocks 2. The first ends of the two shoe blocks 2 are pivotally connected, and the second ends of the two shoe blocks 2 are respectively located on opposite sides of the transmission section 11 along its thickness direction. The first elastic element includes a tension spring 3, which is connected between the two shoe blocks 2.

[0062] That is, when the drive shaft 1 rotates in the first direction, it will drive the second ends of the two shoe blocks 2 to move away from each other in a direction so as to come into contact with the brake drum and realize the braking function. At the same time, the tension spring 3 applies a pulling force to the second ends of the two shoe blocks 2 to move closer to each other. When the brake lever is released, the tension spring 3 pulls the shoe blocks 2 back to their original position and drives the drive shaft 1 to rotate in the second direction.

[0063] The wheel according to an embodiment of the present invention includes a drum brake as described in any of the above embodiments. The brake drum of the drum brake is connected to the wheel hub of the vehicle.

[0064] The technical advantages of the wheel according to the present invention are the same as those of the drum brake in the above embodiments, and will not be repeated here.

[0065] The vehicle according to the present invention includes wheels as described in the above embodiments.

[0066] The technical advantages of the vehicle according to this utility model embodiment are the same as the technical advantages of the wheel in the above embodiment, and will not be repeated here.

[0067] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0068] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0069] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0070] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0071] In this utility model, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0072] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A drum brake, characterized in that, include: Brake drum; A shoe block assembly, the shoe block assembly including a drive shaft (1), a shoe block (2) and a first elastic element, the drive shaft (1) being pivotally connected to the brake drum about its axis, the drive shaft (1) being connected to the shoe block (2), the drive shaft (1) being rotated about its axis in a first direction to drive the shoe block (2) from an initial position toward a braking position abutting against the brake drum, the first elastic element pressing the shoe block (2) toward the initial position; A one-way ratchet assembly includes a crank (4), a ratchet (5), and a pawl (6). The ratchet (5) is coaxially connected to the drive shaft (1). The crank (4) is pivotally connected to the ratchet (5) around the axis of the ratchet (5). The pawl (6) is disposed on the crank (4) and engages with the ratchet (5). The crank (4) is adapted to drive the ratchet (5) to rotate synchronously in a first direction via the pawl (6).

2. The drum brake according to claim 1, characterized in that, The pawl (6) is movably connected to the crank (4), and the one-way ratchet assembly further includes a second elastic element that connects the pawl (6) and the crank (4), and the second elastic element presses the pawl (6) toward the ratchet (5).

3. The drum brake according to claim 2, characterized in that, The crank (4) is provided with a mounting hole, the ratchet (5) is clearance-fitted into the mounting hole, the inner wall of the mounting hole is provided with a first guide hole (41), the extension direction of the first guide hole (41) is orthogonal to the axial direction of the ratchet (5), and the pawl (6) is slidably fitted into the first guide hole (41). The first guide hole (41) has a first limiting surface (43) at one end away from the mounting hole. The pawl (6) has a second limiting surface (611) opposite to the first limiting surface (43) along the extension direction of the first guide hole (41). The second elastic element includes a compression spring (10), which is located in the first guide hole (41) and sandwiched between the first limiting surface (43) and the second limiting surface (611).

4. The drum brake according to claim 3, characterized in that, The crank (4) is provided with a second guide hole (42) extending from its outer wall surface to the first limiting surface (43), and the extension direction of the second guide hole (42) is consistent with the extension direction of the first guide hole (41). The pawl (6) includes a first guide section (61) and a second guide section (62) connected together. The first guide section (61) is slidably fitted into the first guide hole (41), and the second guide section (62) is slidably fitted into the second guide hole (42). A portion of the second guide section (62) protrudes from the outer wall surface of the crank (4).

5. The drum brake according to claim 4, characterized in that, The outer contour of the cross section of at least one of the first guide hole (41) and the second guide hole (42) is not circular.

6. The drum brake according to claim 3, characterized in that, The inner wall of the mounting hole is provided with a first annular groove, the outer circumferential surface of the ratchet (5) is provided with a second annular groove, and the drum brake also includes a retaining ring (7), which is disposed in the first annular groove and the second annular groove.

7. The drum brake according to claim 6, characterized in that, The mounting hole includes a first hole segment and a second hole segment arranged along its axial direction. The diameter of the first hole segment is smaller than the diameter of the second hole segment, and the first annular groove is provided on the inner wall surface of the second hole segment. The ratchet (5) includes a first shaft segment (51), a tooth segment (52), and a second shaft segment (53) connected sequentially along its axial direction. The diameter of the first shaft segment (51), the tooth tip circle diameter of the tooth segment (52), and the diameter of the second shaft segment (53) increase sequentially. The second annular groove is provided on the outer circumferential surface of the second shaft segment (53). The first shaft segment (51) is clearance-fitted into the first hole segment, and the tooth segment (52) and the second shaft segment (53) are clearance-fitted into the second hole segment. The gap between the first shaft segment (51) and the first hole segment is smaller than the gap between the tooth segment (52) and the second hole segment.

8. The drum brake according to any one of claims 1-7, characterized in that, The drive shaft (1) includes a drive section (11), an intermediate section (12) and a threaded section (13) connected sequentially along its axial direction. The drive section (11) is connected to the shoe block (2) in a drive connection. The drum brake also includes a reverse-thread nut (9). The reverse-thread nut (9) is threadedly connected to the threaded section (13) and located on the side of the crank (4) away from the shoe block (2). The ratchet (5) is sleeved on the intermediate section (12) and sandwiched between the drive section (11) and the reverse-thread nut (9).

9. The drum brake according to claim 8, characterized in that, The inner hole of the ratchet (5) is a spline hole, the outer contour of the cross section of the middle section (12) is not circular, and at least a portion of the middle section (12) is disposed in at least one keyway of the spline hole.

10. The drum brake according to claim 8, characterized in that, The outer contour of the cross section of the transmission section (11) is rectangular. There are two hoof blocks (2). The first ends of the two hoof blocks (2) are pivotally connected. The second ends of the two hoof blocks (2) are respectively located on opposite sides of the transmission section (11) along its thickness direction. The first elastic element includes a tension spring (3) connected between the two shoes (2).

11. A wheel, characterized in that, Includes the drum brake according to any one of claims 1-10.

12. A vehicle, characterized in that, Including the wheel as described in claim 11.

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