An adaptive compensation drum brake
By designing an adaptive compensation mechanism, and utilizing the meshing of components such as cams and driven wheels, as well as limiting blocks, the problems of uneven wear and complex structure in drum brakes are solved, achieving the effect of rapid compensation for braking gaps and uniform wear.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG LIUHE IND CO LTD
- Filing Date
- 2026-04-03
- Publication Date
- 2026-06-02
AI Technical Summary
Existing drum brakes suffer from complex structures and difficulty in achieving effective wear uniformity in terms of wear compensation, especially the uneven braking force and wear caused by rapid wear of the leading shoe, which existing improvement solutions have failed to effectively solve.
An adaptive compensation mechanism is adopted, which uses a combination of cam, driven wheel, swing arm, main tension spring and auxiliary tension spring. Through the meshing of the tooth structure and the design of the limit block, the brake shoe can quickly compensate for the brake clearance during the wear process, avoiding complex structure and adjustment requirements.
It enables rapid elimination of brake clearance over a wide range, improves the contact uniformity between brake shoes and brake drum, enhances braking performance and wear uniformity, and simplifies structural design.
Smart Images
Figure CN122129501A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of vehicle parts, in particular to a drum brake with self-adaptive compensation. BACKGROUND
[0002] The drum brake pushes the brake shoe outward by hydraulic pressure, makes the friction plate press against the inner wall of the brake drum rotating with the wheel, and realizes deceleration by friction. At present, it has the following characteristics and functions: wear compensation relies on the automatic clearance adjustment mechanism, when the clearance increases, the ratchet mechanism will automatically adjust the length of the connecting rod to restore the optimal clearance; the wear of the friction plate is uneven, and the wear speed of the leading shoe is about 2-2.5 times that of the trailing shoe.
[0003] The wear of the leading shoe is faster than that of the trailing shoe in the drum brake, and the fundamental reason is the "self-increasing force effect" - the friction of the leading shoe will further increase its pressure on the brake drum (when the vehicle is moving forward), resulting in significantly higher braking force and wear than the trailing shoe; the existing drum brake mode with the shoe plate root as the fulcrum, when the shoe plate is pushed by hydraulic pressure to swing around the lower end of the supporting pin (or eccentric shaft), the shoe plate does not translate to approach the brake hub, but swings to approach, which inevitably leads to serious uneven wear of each part. Therefore, to overcome this problem, there are also double-leading shoe designs (two shoe plates are symmetrically distributed around the center) and bidirectional double-leading shoe designs (two shoe plates are symmetrically distributed in the plane, which requires two hydraulic pushing units or a hydraulic pushing unit to trigger the linkage structure), and the current two ways have relatively complex structures, linkage structures or hydraulic pipelines need to be bypassed around the center of the hub (such as the patents with application numbers CN201911363793.2, CN201410718593.5, CN201710807278.3, etc.), and it is difficult to realize wear compensation on this basis, which needs to be improved. SUMMARY
[0004] The present application is to solve the problems in the prior art and provides a drum brake that can compensate for the brake clearance caused by the wear of the brake shoe in a larger range.
[0005] To achieve the above objectives, the present invention adopts the following technical solution: an adaptive compensation drum brake, characterized in that it includes a brake drum, a brake base plate located inside the brake drum, and two brake shoes symmetrically mounted on the brake base plate. The middle part of each brake shoe is connected to the brake base plate via a floating clamp. A brake pump capable of driving the brake shoe to swing around its root is provided between the tops of the two brake shoes. A displacement compensation mechanism capable of driving the brake shoe root to expand outward when the brake shoe swings is provided between the root of the brake shoe and the brake base plate. The displacement compensation mechanism includes a cam, a driven wheel, a swing arm, a main tension spring, an auxiliary tension spring, and a limiting block. Both the cam and the driven wheel... The swing arm is rotatably connected to the brake base plate and fixed to the driven wheel. The main tension spring connects the cam's convex point to the brake shoe. The arc surface of the cam meshes with the driven wheel through a tooth structure. The auxiliary tension spring connects the cam's axis to the outer end of the swing arm. The root of the brake shoe abuts against the cam. When the cam's convex point swings away from the center of the brake drum, it can drive the root of the brake shoe to expand outward. When the outer end of the swing arm abuts against the limiting block, the line connecting the cam axis and the driven wheel axis forms an angle of 165-175° with the swing arm, and the outer end of the swing arm is located inside the line connecting the cam axis and the driven wheel axis. The diameter corresponding to the arc surface on the cam is 3-10 times the diameter of the driven wheel.
[0006] The typical swing angle of the brake shoe is between 5 and 8 degrees. Since the main tension spring connects the cam's cam protrusion to the brake shoe, the cam protrusion tends to swing along with the brake shoe. This allows the main tension spring to not only drive the cam to press against the root of the brake shoe but also to reset the cam's position. To prevent brake shoe wear from increasing clearance and causing the brake shoe to fail to effectively press against the brake drum at a small swing angle, this design utilizes the arc surface of the cam meshing with a driven gear tooth. In the initial state of the brake shoe, the swing arm is located between the center of the cam and the center of the driven gear. Inside the line and limited by the limiting block, the auxiliary tension spring cannot drive the driven wheel to rotate at this time. When the brake shoe swings to achieve braking, the cam swings at a smaller angle, while the driven wheel swings at a larger angle. The swing of the driven wheel causes the outer end of the swing arm to cross the line connecting the center of the cam and the center of the driven wheel. That is, it can quickly make the outer end of the swing arm located outside the line connecting the center of the cam and the center of the driven wheel. At this time, the auxiliary tension spring can quickly drive the driven wheel to rotate, thereby driving the cam to rotate, and then driving the cam's convex point to press against the brake shoe and drive the brake shoe to open outward.
[0007] Since the auxiliary tension spring drives the cam to rotate after the rocker arm passes the dead angle of the swing, the lever effect of the rocker arm can quickly apply torque to the driven wheel, thereby quickly transferring to the cam to apply the outward thrust of the brake shoe. The brake clearance is then eliminated. Compared with the traditional compensation method, this solution does not require a complex structure, nor does it require the adjustment of the connection position at the root of the brake shoe. Instead, it ignores the wear of the brake shoe within a certain range and achieves the elimination of clearance and the close proximity of the brake shoe and the brake drum with a faster response speed.
[0008] When the brake shoes are reset, the reset lever or reset spring at the top of the brake shoes drives the tops of the two brake shoes to come close together, the brake shoes swing back, and the main tension spring pulls back the cam position, causing the driven wheel to rotate back to the initial position, that is, the outer end of the swing arm is located within the line connecting the center of the cam and the center of the driven wheel.
[0009] Furthermore, the main tension spring includes spring one, spring two, and a cable. One end of spring one is connected to the cam's protrusion, and the other end of spring one is connected to one end of the cable. One end of spring two is connected to the other end of the cable, and the other end of spring two is fixed to the brake base plate. Spring two is located inside spring one. A guide wheel is rotatably connected to the brake shoe, and the cable is pulled by the guide wheel.
[0010] The main tension spring consists of three parts: spring one, spring two, and cable. The traction angle is controlled by the guide wheel, so that the swaying of the cam has little impact on the tension of the main tension spring. This is because during the braking process of the cam swaying, the connection point between spring one and the cam is close to the connection point between spring two and the brake base plate. The reduction in the distance between the two compensates to some extent for the increase in displacement between the guide wheel and the cam cam cam. This prevents the main tension spring from causing an increase in preload or a significant increase in preload during the cam swaying process. Excessive tension in the main tension spring would delay the swing amplitude of the swing arm and the swing speed after exceeding the critical point.
[0011] Furthermore, the brake shoe is provided with a clearance hole for avoiding the connection point between the second spring and the brake base plate.
[0012] Furthermore, the root of the brake shoe has a first abutting surface located outside the cam axis and a second abutting surface at an angle of 100 to 130° to the first abutting surface; before the brake pump is started, the first abutting surface abuts against the transition surface between the arc surface and the cam's protrusion, and the second abutting surface abuts against the position of the cam's protrusion.
[0013] Furthermore, before the brake pump is started, the cam's convex point, the cam's axis, and the driven wheel's axis are all on the same straight line.
[0014] Furthermore, the two displacement compensation mechanisms share the same limit block.
[0015] Furthermore, the floating clamping device includes a threaded hole on the brake base plate, a stepped hole on the brake shoe, and a bolt that mates with the threaded hole. Two sliding plates are provided in the stepped hole. The sliding plates have an arc surface that matches the inner wall of the large diameter section of the stepped hole and a flat surface. The middle part of the bolt is located between the two flat surfaces.
[0016] Furthermore, a preload spring 1 is provided between the head of the bolt and the upper end face of the slide plate, and a preload spring 2 is provided between the lower end face of the slide plate and the brake base plate, both of which are sleeved on the bolt.
[0017] The floating clamping device can also be a clamping spring or other structure. For example, the clamping spring method used in the prior art will limit the floating space of the brake shoe. In this solution, two sliding plates with minor arcs are used, and a rectangular sliding groove is formed between the two sliding plates. The sliding groove allows the bolt to move in it. In addition, the two sliding plates can also rotate in the stepped hole, which allows the rectangular sliding groove to rotate, thereby increasing the floating space and the clamping force is not weak, and the position of the plates between the brake shoe and the brake base plate is stable. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the structure of the drum brake before braking.
[0019] Figure 2 This is a schematic diagram of the structure of this drum brake during braking.
[0020] Figure 3 for Figure 1 A magnified view of part A in the middle.
[0021] Figure 4 for Figure 2 A magnified view of part B in the middle.
[0022] Figure 5 for Figure 4 A magnified view of part C in the middle.
[0023] Figure 6 This is a cross-sectional view of the floating clamp.
[0024] Figure 7 This is a schematic diagram of the structure of the floating clamp bolt and the sliding plate.
[0025] Figure 8 This is a top view of the floating clamp.
[0026] Legend: 1. Brake drum; 2. Brake base plate; 3. Brake shoe; 31. First pressure surface; 32. Second pressure surface; 41. Cam; 42. Driven wheel; 43. Swing arm; 44. Limit block; 45. Auxiliary tension spring; 46. Spring 1; 47. Spring 2; 48. Cable; 49. Guide wheel; 5. Clearance hole; 61. Threaded hole; 62. Stepped hole; 63. Bolt; 64. Slide plate; 65. Preload spring 1; 66. Preload spring 2. Detailed Implementation
[0027] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.
[0028] like Figures 1 to 5 As shown, the system includes a brake drum 1, a brake base plate 2 located inside the brake drum 1, and two brake shoes 3 symmetrically mounted on the brake base plate 2. The middle part of the brake shoes 3 is connected to the brake base plate 2 via a floating clamp. A brake pump capable of driving the brake shoes 3 to swing around their roots is provided between the tops of the two brake shoes 3. A displacement compensation mechanism capable of driving the roots of the brake shoes 3 to expand outward when they swing is provided between the roots of the brake shoes 3 and the brake base plate 2. The displacement compensation mechanism includes a cam 41, a driven wheel 42, a rocker arm 43, a main tension spring, an auxiliary tension spring 45, and a limiting block 44. The cam 41 and the driven wheel 42 are both rotatably connected to the brake base plate 2, and the rocker arm 43 is fixed to the driven wheel 42. The main tension spring connects the cam 41's protrusion to the brake shoe 3. The arc surface of the cam 41 meshes with the driven wheel 42 through a tooth structure. The auxiliary tension spring 45 connects the cam 41's shaft to the outer end of the rocker arm 43. The root of the brake shoe 3 abuts against the cam 41. When the cam 41's protrusion swings away from the center of the brake drum 1, it can drive the root of the brake shoe 3 to expand outward. When the outer end of the rocker arm 43 abuts against the limit block 44, the line connecting the cam 41's shaft and the driven wheel 42's shaft forms an angle of 165 to 175° with the rocker arm 43. The outer end of the rocker arm 43 is located inside the line connecting the cam 41's shaft and the driven wheel 42's shaft. The diameter corresponding to the arc surface on the cam 41 is 3 to 10 times the diameter of the driven wheel 42.
[0029] The typical swing angle of brake shoe 3 is between 5 and 8°. Since the main tension spring connects the cam 41's protrusion to brake shoe 3, the position of the cam 41's protrusion tends to swing along with brake shoe 3. This allows the main tension spring to not only drive cam 41 to press against the root of brake shoe 3, but also to reset the position of cam 41. To prevent the brake shoe 3 from wearing out and causing increased clearance, which would prevent the root of brake shoe 3 from effectively pressing against brake drum 1 at a small swing angle, this design utilizes the arc surface of cam 41 to mesh with a driven wheel 42. In the initial state of brake shoe 3, the swing arm 43 is located inside the line connecting the center of cam 41 and the center of driven wheel 42. Furthermore, due to the limitation of the limiting block 44, the auxiliary tension spring 45 cannot drive the driven wheel 42 to rotate at this time. When the brake shoe 3 swings to achieve braking, the cam 41 swings at a small angle, while the driven wheel 42 swings at a large angle. The swing of the driven wheel 42 causes the outer end of the swing arm 43 to cross the line connecting the center of the cam 41 and the center of the driven wheel 42. That is, it can quickly make the outer end of the swing arm 43 located outside the line connecting the center of the cam 41 and the center of the driven wheel 42. At this time, the auxiliary tension spring 45 can quickly drive the driven wheel 42 to rotate, thereby driving the cam 41 to rotate, thereby driving the cam 41 to press against the brake shoe 3 and drive the brake shoe 3 to expand outward.
[0030] Since the auxiliary tension spring 45 drives the cam 41 to rotate after the rocker arm 43 passes the swing dead angle, the lever action of the rocker arm 43 can quickly apply torque to the driven wheel 42, thereby quickly transferring to the cam 41 to apply the outward thrust of the brake shoe 3. The brake clearance is then eliminated. Compared with the traditional compensation method, this solution does not require a complex structure, nor does it require adjusting the connection position of the brake shoe 3 root. Instead, it ignores the wear of the brake shoe 3 within a certain range and achieves the elimination of clearance and the close proximity of the brake shoe 3 to the brake drum 1 with a faster response speed.
[0031] When the brake shoe 3 is reset, the reset lever or reset spring at the top of the brake shoe 3 drives the tops of the two brake shoes 3 to come close together, the brake shoe 3 swings back, and the main tension spring pulls back the position of the cam 41, causing the driven wheel 42 to rotate back to the initial position, that is, the outer end of the swing arm 43 is located within the line connecting the center of the cam 41 and the center of the driven wheel 42.
[0032] The main tension spring includes spring 46, spring 47, and cable 48. One end of spring 46 is connected to the protrusion of cam 41, and the other end of spring 46 is connected to one end of cable 48. One end of spring 47 is connected to the other end of cable 48, and the other end of spring 47 is fixed on brake base plate 2. Spring 47 is located inside spring 46. A guide wheel 49 is rotatably connected to brake shoe 3, and cable 48 is pulled by guide wheel 49. The main tension spring consists of three parts: spring 46, spring 47, and cable 48. The traction angle is controlled by the guide wheel 49, so that the swing of the cam 41 has little impact on the tension of the main tension spring. This is because during the braking process of the cam 41 swinging, the connection point between spring 46 and cam 41 is close to the connection point between spring 47 and brake base plate 2. The reduction in the distance between the two compensates to some extent for the increase in displacement between the guide wheel 49 and the cam 41 convex point, so that the main tension spring will not cause an increase in preload or a large increase in preload during the swing of the cam 41. Because if the tension of the main tension spring is too large, it will delay the swing amplitude of the swing arm 43 and the swing speed after crossing the critical point.
[0033] The brake shoe 3 is provided with a clearance hole 5 for avoiding the connection point between the second spring 47 and the brake base plate 2. The root of the brake shoe 3 has a first abutment surface 31 located outside the axis of the cam 41 and a second abutment surface 32 at an angle of 100 to 130° to the first abutment surface 31. Before the brake pump is started, the first abutment surface 31 abuts against the transition surface between the arc surface and the protrusion of the cam 41, and the second abutment surface 32 abuts against the position of the protrusion of the cam 41.
[0034] Before the brake pump is started, the cam 41 convex point, the cam 41 axis, and the driven wheel 42 axis are all on the same straight line.
[0035] like Figure 6 , Figure 7 and Figure 8 As shown, the floating clamping device includes a threaded hole 61 on the brake base plate 2, a stepped hole 62 on the brake shoe 3, and a bolt 63 that mates with the threaded hole 61. Two sliding plates 64 are disposed within the stepped hole 62. Each sliding plate 64 has an arcuate surface that adapts to the inner wall of the large-diameter section of the stepped hole 62 and a flat surface. The middle part of the bolt 63 is located between the two flat surfaces. A preload spring 65 is sleeved on the bolt 63 between the head of the bolt 63 and the upper end face of the sliding plate 64, and a preload spring 66 is sleeved on the bolt 63 between the lower end face of the sliding plate 64 and the brake base plate 2.
[0036] The floating clamping device can also be a clamping spring or other structure. For example, the clamping spring method used in the prior art would limit the floating space of the brake shoe 3. In this solution, two sliding plates 64 with minor arcs are used, and a rectangular sliding groove is formed between the two sliding plates 64. The sliding groove allows the bolt 63 to move in it. In addition, the two sliding plates 64 can also rotate in the stepped hole 62, thereby allowing the rectangular sliding groove to rotate, which increases the floating space and the clamping force is not weak. The layer position between the brake shoe 3 and the brake base plate 2 is stable.
[0037] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.
Claims
1. An adaptive compensation drum brake, characterized in that, The system includes a brake drum (1), a brake base plate (2) located inside the brake drum (1), and two brake shoes (3) symmetrically mounted on the brake base plate (2). The middle part of the brake shoes (3) is connected to the brake base plate (2) through a floating clamp. A brake pump capable of driving the brake shoes (3) to swing around their roots is provided between the tops of the two brake shoes (3). A displacement compensation mechanism capable of driving the roots of the brake shoes (3) to expand outward when the brake shoes (3) swing is provided between the roots of the brake shoes (3) and the brake base plate (2). The displacement compensation mechanism includes a cam (41), a driven wheel (42), a swing arm (43), a main tension spring, an auxiliary tension spring (45), and a limiting block (44). The cam (41) and the driven wheel (42) are rotatably connected to the brake base plate (2), and the swing arm (43) is fixed to the driven wheel (42). The main tension spring connects the cam (41) to the brake shoe (3). The arc surface of the cam (41) meshes with the driven wheel (42) through a tooth structure. The auxiliary tension spring (45) connects the axis of the cam (41) to the outer end of the swing arm (43). The root of the brake shoe (3) abuts against the cam (41). When the cam (41) swings away from the center of the brake drum (1), it can drive the root of the brake shoe (3) to open outward. When the outer end of the swing arm (43) abuts against the limit block (44), the line connecting the axis of the cam (41) and the axis of the driven wheel (42) forms an angle of 165 to 175° with the swing arm (43). The outer end of the swing arm (43) is located inside the line connecting the axis of the cam (41) and the axis of the driven wheel (42). The diameter corresponding to the arc surface on the cam (41) is 3 to 10 times the diameter of the driven wheel (42).
2. The adaptive compensation drum brake according to claim 1, characterized in that, The main tension spring includes spring one (46), spring two (47) and cable (48). One end of spring one (46) is connected to the protrusion of cam (41), and the other end of spring one (46) is connected to one end of cable (48). One end of spring two (47) is connected to the other end of cable (48), and the other end of spring two (47) is fixed on brake base plate (2). Spring two (47) is located inside spring one (46). A guide wheel (49) is rotatably connected to the brake shoe (3), and the cable (48) is pulled by the guide wheel (49).
3. The adaptive compensation drum brake according to claim 2, characterized in that, The brake shoe (3) is provided with a clearance hole (5) for avoiding the connection point between the second spring (47) and the brake base plate (2).
4. The adaptive compensation drum brake according to claim 3, characterized in that, The root of the brake shoe (3) has a first pressing surface (31) located outside the axis of the cam (41) and a second pressing surface (32) at an angle of 100 to 130° to the first pressing surface (31); before the brake pump is started, the first pressing surface (31) abuts against the transition surface between the arc surface and the protrusion of the cam (41), and the second pressing surface (32) abuts against the position of the protrusion of the cam (41).
5. An adaptive compensation drum brake according to claim 1, 2, 3, or 4, characterized in that, Before the brake pump is started, the cam (41) convex point, the cam (41) axis and the driven wheel (42) axis are on the same straight line.
6. An adaptive compensation drum brake according to claim 1, 2, 3, or 4, characterized in that, The two displacement compensation mechanisms share the same limit block (44).
7. An adaptive compensation drum brake according to claim 1, 2, 3, or 4, characterized in that, The floating clamping device includes a threaded hole (61) on the brake base plate (2), a stepped hole (62) on the brake shoe (3), and a bolt (63) that mates with the threaded hole (61). Two sliding plates (64) are provided inside the stepped hole (62). The sliding plate (64) has an arc surface that matches the inner wall of the large diameter section of the stepped hole (62) and a flat surface. The middle part of the bolt (63) is located between the two flat surfaces.
8. The adaptive compensation drum brake according to claim 7, characterized in that, A preload spring (65) is provided between the head of the bolt (63) and the upper end face of the slide plate (64), and a preload spring (66) is provided between the lower end face of the slide plate (64) and the brake base plate (2), and a preload spring (66) is provided between the head of the bolt (63) and the upper end face of the slide plate (64), and a preload spring (66) is provided between the lower end face of the slide plate (64) and the brake base plate (2).