Vehicle brake control device

Abstract

The invention discloses a vehicle brake control device which comprises a drum wheel rack, a leading shoe, a trailing shoe and a cam, one end of the leading shoe and one end of the trailing shoe are provided with a first roller and a second roller matched with the cam respectively, the other end of the leading shoe and the other end of the trailing shoe are matched with a pivoting piece to enable the leading shoe and the trailing shoe to swing in a fixed-axis mode, and the cam rotates to push the first roller and the second roller to move outwards during braking. The driving wheel drives the leading shoe and the trailing shoe to swing and expand outwards, so that the leading shoe and the trailing shoe rub with the drum wheel rack to realize braking; the outer contour line of the cam comprises an asymmetric S-shaped curve which enables the moving distance of the first roller and the second roller to be equal or the rotating angle of the leading shoe and the rotating angle of the trailing shoe to be equal in the swinging process of the leading shoe and the trailing shoe. The outward rotating angles (or displacements) of the leading shoe and the trailing shoe on the two sides can be equal in the swinging process of the leading shoe and the trailing shoe, so that the friction lining can achieve the best friction effect, the brake pad can be opened more powerfully, and the brake pad is lighter and more sensitive to use.

Description

Technical Field

[0001] The present application relates to the technical field of vehicle brake control systems or components thereof, and in particular to a vehicle brake control device. Background Art

[0002] Among vehicle braking control devices, the leading shoe drum brake is a common automobile braking system that applies force to the leading shoe or drum to brake the wheels and stop the vehicle. It is highly praised for its powerful braking force, long service life and wide adaptability.

[0003] The braking performance of a vehicle's brake control system is crucial for ensuring stable driving and is a key consideration during vehicle design. When braking with existing brake shoe drum brakes, the driver depresses the brake pedal, and fluid from the master cylinder flows through the oil pipe into the wheel cylinder, increasing the fluid pressure within the wheel cylinder. This pressure, through the cam, pushes the brake shoe outward around the support pin, pressing against the rotating brake drum, generating braking torque to slow or stop the vehicle.

[0004] In a leading-trailing shoe drum brake, the cam is a key component that converts the translational motion of the external push rod into rotational motion, applying torque to the rollers and causing the leading and trailing shoes to rotate. Therefore, studying the rotational state between the cam and the rollers is crucial. When the currently used cam rotates, the rollers connected to one end of the leading and trailing shoes are acted upon by the cam force, causing the brake shoes to rotate and expand outward. When the other end rotates about a fixed axis, the two rollers rotate at different angles (or displacements), resulting in unequal displacements of the leading and trailing shoes (also known as "asymmetric opening"), which prevents the friction lining from achieving optimal friction. Furthermore, most current swing-follower drum brakes roughly apply the centrally symmetrical cams of a translational follower, resulting in asymmetric opening of the swinging brake shoes (i.e., the leading and trailing shoes). Summary of the Invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a vehicle brake control device in which the outward rotation angles (or displacements) of the leading shoes and the trailing shoes on both sides are equal.

[0006] The technical solutions provided by the present invention are as follows: A vehicle brake control device includes a drum frame, a leading shoe, a trailing shoe, and a cam. One end of the leading shoe and the trailing shoe is respectively provided with a first roller and a second roller that cooperate with the cam, and the other end cooperates with a pivot member to enable the leading shoe and the trailing shoe to swing around a fixed axis, so that when braking, the cam rotates to push the first roller and the second roller to move outward, driving the leading shoe and the trailing shoe to swing and expand outward, so that the leading shoe and the trailing shoe rub against the drum frame to achieve braking; the outer contour line of the cam includes an asymmetric S-shaped curve that makes the moving distance of the first roller and the second roller equal or the rotation angle of the leading shoe and the trailing shoe equal during the swinging process.

[0007] Preferably, the asymmetric S-shaped curve is obtained by obtaining the relationship between the cam rotation angle and the movement distance of the first roller / the second roller or the relationship between the cam rotation angle and the rotation angle of the leading shoe / the following shoe according to the required transmission ratio characteristics, and then obtained by the inverse solution method based on the relationship.

[0008] Preferably, the transmission ratio characteristic is constant velocity motion, constant acceleration, constant deceleration, cosine acceleration, sine acceleration or a fifth-order polynomial.

[0009] Preferably, a support slot is provided below the drum frame, and the support slot is used to install a rotation pin, and the rotation pin forms a pivot member to cooperate with the leading shoe and the trailing shoe so that the leading shoe and the trailing shoe can swing around the fixed axis of the rotation pin.

[0010] Preferably, the leading shoe also includes a first drum brake caliper and a first friction lining located outside the first drum brake caliper, the first roller is mounted on one end of the first drum brake caliper, and the other end of the first drum brake caliper is provided with a first non-complete semicircular slot hole; the trailing shoe also includes a second drum brake caliper and a second friction lining located outside the second drum brake caliper, the second roller is mounted on one end of the second drum brake caliper, and the other end of the second drum brake caliper is provided with a second non-complete semicircular slot hole; the rotating pin includes a pin shaft, the first non-complete semicircular slot hole and the second non-complete semicircular slot hole are both coaxially clearance-matched with the pin shaft, so that the leading shoe and the trailing shoe can swing around the rotating pin fixed axis.

[0011] Preferably, a first arc-shaped bayonet for mounting a first friction lining is provided on an outer side of the first drum brake caliper, and a second arc-shaped bayonet for mounting a second friction lining is provided on an outer side of the second drum brake caliper.

[0012] Preferably, the cam includes a cam body and a rotating shaft located on the back of the cam body. A through hole is provided above the drum frame, and the rotating shaft is accommodated in the through hole and is loosely fitted with the through hole. The two sides of the cam body include a first curved surface and a second curved surface, and the axial projections of the first curved surface and the second curved surface form the outer contour line of the cam.

[0013] Preferably, a boss is provided between the cam body and the rotating shaft, and the size of the boss is larger than the size of the through hole.

[0014] Compared with the prior art, the vehicle brake control device of the present invention includes an asymmetric S-shaped curve in which the outer contour line of the cam makes the moving distances of the first roller and the second roller equal or the rotation angles of the leading shoe and the trailing shoe equal during the swinging process. Therefore, the outward rotation angles (or displacements) of the leading shoe and the trailing shoe on both sides are equal during the swinging process of the leading shoe and the trailing shoe, thereby reducing acceleration mutations, preventing flexible impact or rigid impact, reducing the wear of the cam and the roller, and achieving the best friction effect for the friction lining. In addition, the actuating effect is utilized to make the brake pad open more forcefully, making it lighter and more sensitive to use, and the cam torsional opening is larger, the strength is high, and the safety performance is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 A perspective view of a vehicle brake control device according to an embodiment of the present invention; Figure 2 for Figure 1 A front view of the brake control device of the vehicle shown; Figure 3 for Figure 1 A perspective view of a drum frame in a brake control device of the illustrated vehicle; Figure 4 for Figure 1 A perspective view of a leading shoe in a brake control device of the vehicle shown; Figure 5 for Figure 1 A perspective view of a slave shoe in the vehicle brake control device shown; Figure 6 for Figure 1 a perspective view of a transfer pin in a brake control device of the illustrated vehicle; Figure 7 for Figure 1 A perspective view of the cam in the vehicle's brake control system is shown. DETAILED DESCRIPTION

[0017] In order to help those skilled in the art better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of this application.

[0018] It should be noted that when an element is referred to as being “fixed on” or “set on” another element, it can be directly on the other element or indirectly set on the other element; when an element is referred to as being “connected to” another element, it can be directly connected to the other element or indirectly connected to the other element.

[0019] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. Throughout the description of this application, "plurality" or "several" means two or more, unless otherwise specifically defined.

[0021] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which this application can be implemented. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in this application without affecting the efficacy and purpose that can be achieved by this application.

[0022] like Figures 1 to 7 As shown, an embodiment of the present invention provides a vehicle brake control device, including a drum frame 1, a leading shoe 2, a trailing shoe 3, a cam 3, and a rotation pin 5.

[0023] like Figure 3 As shown, in this embodiment, a through hole 101 for accommodating the rotating shaft of the cam 3 is provided above the drum frame 1 , and a supporting slot hole 102 for installing the rotating pin 5 is provided below the drum frame 1 .

[0024] like Figure 4As shown, in this embodiment, the leading shoe 2 comprises a first drum brake caliper 203, a first friction lining 202, and a first roller 201 that cooperates with the cam 3. The first drum brake caliper 203 is provided with a first position-limiting support through-hole 206 for limiting the position and rolling of the first roller 201. The first drum brake caliper 203 is provided with a first non-completely semicircular slot 204 for cooperating with the rotation pin 5, enabling the first drum brake caliper 203 to rotate about the rotation pin 5 when subjected to force. The first drum brake caliper 203 also has a first arcuate bayonet 205 for mounting the first friction lining 202.

[0025] like Figure 5 As shown, in this embodiment, the follower shoe 4 comprises a second drum brake caliper 403, a second friction lining 402, and a second roller 401 that cooperates with the cam 3. The second drum brake caliper 403 has a second position-limiting support through-hole 406 for limiting the position and rolling of the second roller 401. The second drum brake caliper 403 has a second non-completely semicircular slot 404 for cooperating with the rotation pin 5, enabling the second drum brake caliper 403 to rotate about the rotation pin 5 when subjected to force. The second drum brake caliper 403 has a second arcuate bayonet 405 for mounting the second friction lining 402.

[0026] like Figure 6 As shown, in this embodiment, the rotation pin 5 is used to limit the position of the leading shoe 2 and the trailing shoe 4 at both ends. It is a shaft-like component with a pin shaft 501, which is coaxially and clearance-fitted with the first non-complete semicircular slot 204 of the leading shoe 2 and the second non-complete semicircular slot 404 of the trailing shoe 4, forming a pivot joint, allowing the leading shoe 2 and the trailing shoe 4 to rotate around the rotation pin 5. Of course, in other embodiments, the rotation pin can be omitted and other structures (such as a protruding shaft provided on the drum frame) can be used, as long as a pivot joint is formed to allow the leading shoe and the trailing shoe to swing around the fixed axis.

[0027] like Figure 7 As shown, in this embodiment, the cam 3 is an asymmetric S-shaped curve cam, comprising a cam body 300 with a boss 301 on the back of the cam body 300. The boss 301 is connected to a rotating shaft 302. The rotating shaft 302 is fitted with a clearance fit in the through hole 101 of the drum frame 1, allowing the cam 3 to rotate within the through hole 101. The boss 301 is larger than the through hole 101 to isolate the cam body 300 from the drum frame 1.

[0028] The cam body is provided with a first curved surface 303 and a second curved surface 304 on both sides, and the axial projections of the first curved surface 303 and the second curved surface 304 form the outer contour line of the cam. The outer contour line includes an asymmetric S-shaped curve that makes the moving distances of the first roller 201 and the second roller 401 equal or the rotation angles of the leading shoe 2 and the following shoe 4 equal during the swinging process of the leading shoe 2 and the following shoe 4. It should be noted that the moving distance of the first roller 201 and the second roller 401 and the rotation angle of the leading shoe 2 and the following shoe 4 are two different characterization parameters, but the final effect achieved is the same, so sometimes only one of them is selected for description in this specification. The first curved surface 303 and the second curved surface 304 are also provided with chamfers at both ends (such as Figure 7 As shown, a first chamfer 305 and a second chamfer 306 are respectively provided at both ends of the second curved surface 304).

[0029] This asymmetric S-shaped curve is derived by inversely solving the relationship between the cam rotation angle and the travel distance of the first / second roller, or the relationship between the cam rotation angle and the rotation angle of the leading / following shoe, based on the desired transmission ratio. Because the leading and following shoes are oscillating components, the resulting profile is an asymmetric S-shaped curve. The transmission ratio characteristic can be constant velocity, constant acceleration, constant deceleration, cosine acceleration, sine acceleration, or a fifth-order polynomial (although other characteristics are possible, depending on design requirements).

[0030] When the vehicle brake control device is in use, a brake chamber (or brake cylinder) is fixedly mounted on the top of the drum bracket 1. The brake chamber converts gas pressure into mechanical force, pushing the chamber push rod forward. The adjustment arm and the rotating shaft 302 of the cam 3 convert the push rod's translational displacement into rotational displacement, causing the cam 3 to rotate and apply force to the first roller 201 and the second roller 401. During braking, the starting cam 3 and the first and second rollers 201 and 401 cooperate via the first and second curved surfaces 303 and 304, and can be considered rigidly connected and move together. As cam 3 rotates, first roller 201 and second roller 401 begin to rotate along their corresponding curved surfaces, simultaneously driving first drum brake caliper 203 and second drum brake caliper 403 to expand outward and rotate about the pivot pin 5. Due to the specific asymmetric S-shaped curve on either side of cam 3 (an asymmetric S-shaped curve that ensures equal travel distances or rotation angles of the first and second rollers during the swinging motion of the leading and trailing shoes), when cam 3 rotates through a certain angle, the leading and trailing shoes 2 and 4 on either side achieve equal outward expansion displacement, eliminating the significant torque differences caused by unequal displacements. This results in friction between the first and second friction linings 202 and 402 and the outer brake drum, generating opposing torques and thus achieving deceleration. It should be noted that the first curved surface 303 and the second curved surface 304 of the cam 3 in this embodiment can achieve a constant transmission ratio. As the cam 3 rotates, the expansion displacement (angle) of the leading shoe 2 and the trailing shoe 4 increases linearly at a certain transmission ratio (in this case, the transmission ratio is constant), resulting in smoother and gentler braking. In the later stages of the braking stroke, greater torque can be achieved with less force. Alternatively, when the cam 3 rotates rapidly, the leading shoe 2 and the trailing shoe 4 can expand outward more rapidly, meeting emergency braking requirements. When the cam 3 reaches its maximum rotation angle, the first roller 201 and the second roller 401 are firmly positioned due to the limiting action, preventing misalignment and disengagement. After the braking operation is completed, the cam 3 begins to rotate in the reverse direction to reset itself. Simultaneously, the leading shoe 2 and the trailing shoe 4 also begin to reset themselves around the pivot pin 5, and the friction linings on both sides also disengage from the outer brake drum. Finally, the brake returns to its original position, ready for the next braking operation.

[0031] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A vehicle brake control device, characterized in that: The invention comprises a drum frame, a leading shoe, a trailing shoe and a cam. One end of the leading shoe and the trailing shoe is respectively provided with a first roller and a second roller which cooperate with the cam, and the other end cooperates with a pivot member so that the leading shoe and the trailing shoe can swing around a fixed axis, so that when braking, the cam rotates to push the first roller and the second roller to move outward, driving the leading shoe and the trailing shoe to swing and expand outward, so that the leading shoe and the trailing shoe rub against the drum frame to achieve braking; the outer contour line of the cam includes an asymmetric S-shaped curve which makes the moving distance of the first roller and the second roller equal or the rotation angle of the leading shoe and the trailing shoe equal during the swinging process.

2. The vehicle brake control device according to claim 1, wherein: The asymmetric S-shaped curve is obtained by obtaining the relationship between the cam rotation angle and the movement distance of the first roller / the second roller or the relationship between the cam rotation angle and the rotation angle of the leading shoe / the following shoe according to the required transmission ratio characteristics, and then obtained by the inverse solution method based on the relationship.

3. The vehicle brake control device according to claim 2, wherein: The transmission ratio characteristic is constant velocity motion, constant acceleration, constant deceleration, cosine acceleration, sine acceleration or a fifth-order polynomial.

4. The vehicle brake control device according to claim 1, 2 or 3, wherein: A support slot is provided below the drum frame. The support slot is used to install a rotation pin. The rotation pin forms a pivot joint to cooperate with the leading shoe and the trailing shoe so that the leading shoe and the trailing shoe can swing around the fixed axis of the rotation pin.

5. The vehicle brake control device according to claim 4, wherein: The leading shoe also includes a first drum brake caliper and a first friction lining located outside the first drum brake caliper, the first roller is mounted on one end of the first drum brake caliper, and the other end of the first drum brake caliper is provided with a first non-complete semicircular slot; the trailing shoe also includes a second drum brake caliper and a second friction lining located outside the second drum brake caliper, the second roller is mounted on one end of the second drum brake caliper, and the other end of the second drum brake caliper is provided with a second non-complete semicircular slot; the rotating pin includes a pin shaft, the first non-complete semicircular slot hole and the second non-complete semicircular slot hole are both coaxially clearance-matched with the pin shaft, so that the leading shoe and the trailing shoe can swing around the rotating pin fixed axis.

6. The vehicle brake control device according to claim 5, wherein: A first arcuate bayonet for mounting a first friction lining is provided on the outer side of the first drum brake caliper, and a second arcuate bayonet for mounting a second friction lining is provided on the outer side of the second drum brake caliper.

7. The vehicle brake control device according to claim 1, 2 or 3, wherein: The cam includes a cam body and a rotating shaft located on the back of the cam body. A through hole is provided above the drum frame. The rotating shaft is accommodated in the through hole and is loosely fitted with the through hole. Both sides of the cam body include a first curved surface and a second curved surface. The axial projections of the first curved surface and the second curved surface form the outer contour line of the cam.

8. The vehicle brake control device according to claim 7, wherein: A boss is further provided between the cam body and the rotating shaft, and the size of the boss is larger than the size of the through hole.

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