A tappet type disc cam multi-plate drum brake

Abstract

This invention discloses a tappet-type disc cam multi-plate drum brake, relating to the field of vehicle braking technology. It includes a brake drum, a cam disc, and several brake shoes. The cam disc is rotatably disposed within the brake drum, and its rotating surface has several cam action parts arranged circumferentially. Each brake shoe surrounds the cam disc, and its outer surface has friction pads adapted to the brake drum. The inner surface of each brake shoe has tappets corresponding to the cam action parts. As the cam disc rotates, the cam action parts push the corresponding tappets radially outward, thereby pushing the brake shoes and friction pads against the brake drum to generate braking force. This invention features a compact structure, fast force transmission response, uniform pressure application, and convenient maintenance. It can achieve a large braking torque output within a limited space and is suitable for braking systems of various vehicles and mechanical equipment.

Description

Technical Field

[0001] This invention relates to the field of vehicle braking technology, specifically to a tappet-type disc cam multi-plate drum brake. Background Technology

[0002] Existing drum brakes typically employ a single-stage, outward-expanding brake shoe structure, achieving braking through friction between the brake shoe and the inner wall of the brake drum. While this type of structure is mature in manufacturing and relatively inexpensive, it suffers from problems such as limited braking output capacity, uneven stress distribution, significant heat fade, and rapid localized wear under conditions requiring high load capacity, large braking torque, or limited installation space.

[0003] On the other hand, while some existing disc cam-driven braking structures can achieve significant mechanical amplification, they are typically used primarily for clamping single friction pairs or simple friction elements, making it difficult to simultaneously meet the requirements of efficient clamping and uniform circumferential force application for multiple friction pairs. When a brake employs a multi-plate friction structure, if the force path design is unreasonable, uneven clamping force distribution, uneven wear of the friction plates, sluggish response, and incomplete return can easily occur, thus affecting braking reliability and service life.

[0004] Therefore, there is an urgent need to provide a drum brake that is compact in structure, has a fast force transmission response, can achieve radial uniform pressure application, and can drive multiple friction pairs to work stably, so as to improve the load-bearing capacity, braking torque output capacity and working stability of the brake.

[0005] Chinese patent documents, including "An EMB Structure for a Drum Brake" (patent application number: 202511641737.6), "Drum Brake and Vehicle" (patent application number: 201710758838.0), and "Electro-mechanical Spreading Device for Drum Brakes" (patent application number: 202380069197.1), disclose drive structures acting on the brake shoes. However, these drive structures can only act on two brake shoes and are not suitable for multi-plate friction pad structures. Furthermore, they are still prone to uneven distribution of clamping force, uneven wear of friction pads, delayed response, and incomplete return, thus affecting braking reliability and service life. Summary of the Invention

[0006] In view of the defects existing in the prior art, the purpose of this invention is to provide a tappet-type disc cam multi-plate drum brake to solve the technical problems existing in the prior art, such as insufficient braking force, uneven pressure application, uneven wear of friction plates, limited structural arrangement, and poor return effect.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a tappet-type disc cam multi-plate drum brake, including a brake drum, a cam disc, and several brake shoes; the cam disc is rotatably disposed inside the brake drum, and the rotating surface of the cam disc is provided with several cam action parts along the circumferential direction; each brake shoe is arranged around the cam disc, and the outer side of the brake shoe is provided with a friction pad adapted to the brake drum, and the inner side of the brake shoe is provided with a tappet corresponding to each of the cam action parts; the cam action parts push the corresponding tappets to move radially outward as the cam disc rotates, thereby pushing the brake shoes and the friction pads to press against the brake drum, forming a braking force.

[0008] Based on the above technical solution, the cam action part is a raised contour structure, and its contour curve is designed according to a preset motion law to convert the circumferential rotation of the cam disk into the radial displacement of the tappet. The preset motion law includes one or more of the following: trigonometric function motion law, polynomial motion law, or combined motion law.

[0009] Based on the above technical solution, a brake base plate adapted to the brake drum is also included. A cylinder is coaxially arranged inside the center hole of the brake base plate, and the cam disk is rotatably mounted on the cylinder.

[0010] Based on the above technical solution, a guide structure is provided on the inner side of the brake base plate surrounding the cylinder. The guide structure is used to limit the movement direction of the pushrod and improve the force transmission stability, and a rotation space for the cam disk is formed between the guide structure and the cylinder.

[0011] Based on the above technical solution, the guiding structure is a guide hole, a guide groove, or a guide sleeve.

[0012] Based on the above technical solution, the end of the push rod is provided with a contact part that cooperates with the cam action part, and the push rod is sleeved with a return spring. The return spring is located between the brake shoe and the push rod, or connected between the brake shoe and the brake base plate, and is used to drive the brake shoe and the push rod to reset when the brake is released.

[0013] Based on the above technical solution, a drive mechanism for driving the cam disk to rotate is also included.

[0014] Based on the above technical solution, the drive mechanism is installed on the outside of the brake base plate, and the drive shaft of the drive mechanism passes through the brake base plate and is connected to the cam disk through the drive cam.

[0015] Based on the above technical solution, a boss is provided on the outer side of the cam disk, and the boss is provided with a connecting groove adapted to the drive cam.

[0016] Based on the above technical solution, the brake shoe has a ring-shaped, split, or symmetrical structure, with its inner side contacting and cooperating with the tappet, and its outer side connecting or supporting the friction plate.

[0017] The beneficial effects of this invention are as follows: This invention utilizes a brake input shaft to drive a disc cam to rotate, which in turn pushes multiple tappets to move radially. This achieves the conversion of circumferential input to radial clamping force, resulting in a clear force path, high mechanical conversion efficiency, and a compact overall structure. The multiple tappets, distributed circumferentially, provide multi-point synchronous pressure to the brake shoes and friction pad assemblies, reducing localized uneven loading, improving the uniformity of force distribution on the friction pads, and thus enhancing braking stability. Simultaneously, the multi-friction pad structure increases the number of effective friction pairs within a limited installation space, thereby increasing braking torque output and making it more suitable for high-load conditions. The use of return springs to reposition the brake shoes and / or tappets ensures more timely brake release, reducing drag friction and improving operational reliability. Furthermore, the cam disc profile, the number and distribution of tappets, the brake shoe type, and the number of friction pad layers can all be optimized for different vehicle models and operating conditions, resulting in strong structural adaptability and versatility. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the multi-plate drum brake with a tappet-type disc cam in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the tappet-type disc cam multi-plate drum brake after removing the brake drum in an embodiment of the present invention; Figure 3 for Figure 2 Sectional view along the middle AA direction; Figure 4 This is a schematic diagram of the brake base plate in an embodiment of the present invention; Figure 5 This is a schematic diagram of the cam disk structure in an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of the brake shoe, tappet, and friction plate assembly in an embodiment of the present invention.

[0019] Figure label: 1-Brake drum; 2-Brake base plate; 21-Cylinder body; 22-Guide structure; 3-Brake shoe; 31-Friction pad; 32-Tap rod; 33-Return spring; 4-Cam disc; 41-Cam action part; 42-Boss; 43-Connecting groove; 5 - Drive mechanism; 51 - Drive cam. Detailed Implementation

[0020] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0021] In the description of this invention, it should be noted that the directional terms such as "center", "lateral (X)", "longitudinal (Y)", "vertical (Z)", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this invention.

[0022] 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 technical features. Thus, the use of "first" and "second" to define a feature may explicitly or implicitly include one or more of that feature. In the description of this invention, "several" or "a number" means two or more, unless otherwise explicitly specified.

[0023] In this invention, unless otherwise explicitly specified and limited, the terms "assembly," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can also refer to a mechanical connection; they can refer to a direct connection or a connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] In this invention, unless otherwise specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "below," and "over" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Above," "below," and "below" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0025] The following description, in conjunction with the accompanying drawings, further illustrates specific embodiments of the present invention, making the technical solution and its beneficial effects clearer and more explicit. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the invention.

[0026] See Figures 1-6 As shown, this embodiment of the invention provides a tappet-type disc cam multi-plate drum brake, including a brake drum 1. The brake drum is connected to or integrally formed with the braked component to form a braking friction working chamber. The tappet-type disc cam multi-plate drum brake also includes a cam disc 4 and several brake shoes 3. The cam disc 4 is rotatably disposed inside the brake drum 1, and several cam action parts 41 are arranged circumferentially on the rotating surface of the cam disc 4. Each brake shoe 3 is arranged around the cam disc 4, and a friction plate 31 adapted to the brake drum 1 is provided on the outer side of the brake shoe 3. A tappet 32 ​​corresponding to each cam action part 41 is provided on the inner side of the brake shoe 3. As the cam disc 4 rotates, the cam action part 41 pushes the corresponding tappet 32 ​​to move radially outward, thereby pushing the brake shoe 3 and the friction plate 31 to press against the brake drum 1, forming a braking force. Specifically, the brake shoe 3 has a ring-shaped, split, or symmetrical structure, with its inner side contacting and cooperating with the tappet 32, and its outer side connected to or supporting the friction plate 31.

[0027] See Figure 5 As shown, the cam action part 41 has a raised profile structure, and its profile curve is designed according to the preset motion law to convert the circumferential rotation of the cam disk 4 into the radial displacement of the push rod 32. The preset motion law includes one or more of the following: trigonometric function motion law, polynomial motion law, or combined motion law.

[0028] See Figure 4 As shown, the tappet-type disc cam multi-plate drum brake also includes a brake base plate 2 adapted to the brake drum 1. A cylinder 21 is coaxially disposed inside the central hole of the brake base plate 2, and the central hole mates with the brake input shaft. The cam disc 4 is rotatably mounted on the cylinder 21. Specifically, a guide structure 22 is disposed around the cylinder 21 on the inner side of the brake base plate 2. The guide structure 22 is used to limit the movement direction of the tappet 32 ​​and improve the force transmission stability, and a rotation space for the cam disc 4 is formed between the guide structure 22 and the cylinder 21. The guide structure 22 can be a guide hole, a guide groove, or a guide sleeve.

[0029] See Figure 6 As shown, the end of the push rod 32 is provided with a contact portion that cooperates with the cam action part 41, and the push rod 32 is fitted with a return spring 33. The return spring 33 is located between the brake shoe 3 and the push rod 32, or connected between the brake shoe 3 and the brake base plate 2, and is used to drive the brake shoe 3 and the push rod 32 to return to their original positions when the brake is released. The return spring 32 is a compression spring, a disc spring, or a tension spring.

[0030] See Figures 1-3 As shown, the tappet-type disc cam multi-plate drum brake also includes a drive mechanism 5 for driving the cam 51 disc 4 to rotate. Specifically, the drive mechanism 5 is mounted on the outside of the brake base plate 2, and the drive shaft of the drive mechanism 5 passes through the brake base plate 2 and is connected to the cam disc 4 via the drive cam 51. Specifically, the outer side of the cam disc 4 is provided with a boss 42, and the boss 42 is provided with a connecting groove 43 adapted to the drive cam 51.

[0031] In this embodiment, the drive mechanism employs a keyed connection, splined connection, interference fit, pin connection, or an integrally formed structure between the drive motor and the drive cam to ensure reliable torque transmission. It should be noted that the drive device for rotating the cam disc in this embodiment is not limited to the aforementioned combination of drive motor and drive cam. It can also employ worm gear transmission, gear transmission, electric push rod, or other hydraulic or pneumatic drive mechanisms capable of outputting rotational motion, as long as they can drive the cam disc to rotate controllably around its axis.

[0032] The number of tappets 32 and cam actuating parts 41 is two, three, four, or more. Multiple tappets are evenly or non-evenly distributed along the circumference of the cam disk to adapt to different braking force distribution requirements. The number of tappets 32 and cam actuating parts 41 is the same. In this embodiment, the multiple tappets are preferably evenly distributed along the circumference of the cam disk to improve pressure uniformity; in other embodiments, a non-uniform distribution may be adopted according to the braking force distribution requirements. The contour lift of the cam actuating parts can be set to be the same or different to adapt to the clamping requirements of different areas.

[0033] The brake base plate 2 is also provided with mounting positions, limit positions and support positions for mounting the drive mechanism 5, cam disc 4, tappet 32, brake shoe 3 and return spring 32.

[0034] The working principle of this invention is as follows: When the drive motor rotates, it drives the drive cam to rotate, and the drive cam drives the cam disk to rotate synchronously through the drive cam connecting part. As the cam disk rotates, the action parts of each cam push the corresponding tappet to move radially outward, which in turn pushes the brake shoes and friction pads against the brake drum to form braking force.

[0035] When the external driving force is released, the tappet, brake shoes and friction pads return to their original positions under the elastic force of the return spring, the cam disc rotates back to its initial position, and the brake is released.

[0036] This invention features a compact structure, fast force transmission response, uniform pressure application, and convenient maintenance. It can achieve a large braking torque output within a limited space and is suitable for braking systems of various vehicles and mechanical equipment.

[0037] In the description of this specification, references to terms such as "an embodiment," "preferred," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. Illustrative expressions of the above terms in this specification 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.

[0038] This invention is not limited to the embodiments described above. Those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention. Contents not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A tappet-type disc cam multi-plate drum brake, comprising a brake drum (1), characterized in that: It also includes a cam disc (4) and several brake shoes (3); The cam disk (4) is rotatably disposed inside the brake drum (1), and the rotating surface of the cam disk (4) is provided with a plurality of cam action parts (41) along the circumferential direction. Each brake shoe (3) is arranged around the cam disc (4), and the outer side of the brake shoe (3) is provided with a friction plate (31) that is compatible with the brake drum (1), and the inner side of the brake shoe (3) is provided with a push rod (32) that corresponds one-to-one with the cam action part (41). The cam action part (41) pushes the corresponding tappet (32) to move radially outward as the cam disk (4) rotates, thereby pushing the brake shoe (3) and the friction plate (31) to press against the brake drum (1) to form braking force.

2. The tappet-type disc cam multi-plate drum brake as described in claim 1, characterized in that: The cam action part (41) is a raised contour structure, and its contour curve is designed according to the preset motion law to convert the circumferential rotation of the cam disk (4) into the radial displacement of the push rod (32). The preset motion law includes one or more of the following: trigonometric function motion law, polynomial motion law or combined motion law.

3. The tappet-type disc cam multi-plate drum brake as described in claim 1, characterized in that: It also includes a brake base plate (2) adapted to the brake drum (1), and a cylinder (21) is coaxially arranged inside the center hole of the brake base plate (2), and the cam disk (4) is rotatably mounted on the cylinder (21).

4. The multi-plate drum brake with a tappet-type disc cam as described in claim 3, characterized in that: The brake base plate (2) is provided with a guide structure (22) around the cylinder (21) on the inner side. The guide structure (22) is used to limit the movement direction of the push rod (32) and improve the force transmission stability. The guide structure (22) and the cylinder (21) form a rotation space for the cam disk (4).

5. The tappet-type disc cam multi-plate drum brake as described in claim 4, characterized in that: The guide structure (22) is a guide hole, a guide groove, or a guide sleeve.

6. The tappet-type disc cam multi-plate drum brake as described in claim 4, characterized in that: The end of the push rod (32) is provided with a contact part that cooperates with the cam action part (41), and the push rod (32) is sleeved with a return spring (33). The return spring (33) is located between the brake shoe (3) and the push rod (32), or connected between the brake shoe (3) and the brake base plate (2), and is used to drive the brake shoe (3) and the push rod (32) to reset when the brake is released.

7. The tappet-type disc cam multi-plate drum brake as described in claim 3, characterized in that: It also includes a drive mechanism (5) for driving the cam (51) disk (4) to rotate.

8. The tappet-type disc cam multi-plate drum brake as described in claim 7, characterized in that: The drive mechanism (5) is installed on the outside of the brake base plate (2), and the drive shaft of the drive mechanism (5) passes through the brake base plate (2) and is connected to the cam disk (4) through the drive cam (51).

9. The tappet-type disc cam multi-plate drum brake as described in claim 8, characterized in that: The outer side of the cam disk (4) is provided with a boss (42), and the boss (42) is provided with a connecting groove (43) that is adapted to the drive cam (51).

10. The tappet-type disc cam multi-plate drum brake as described in claim 1, characterized in that: The brake shoe (3) has a ring-shaped, split, or symmetrical structure. Its inner side is in contact with the pushrod (32), and its outer side is connected to or supports the friction plate (31).

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