Drum brake mechanism

Abstract

The present invention discloses a drum brake mechanism, belonging to the technical field of vehicle braking. It avoids the bending and telescoping of the internal spring during braking, reduces spring loss, and has a long service life. The drum brake mechanism of the present invention includes a housing, a brake shaft installed on the housing, and a brake assembly. A rocker arm is further provided on the housing. One end of the rocker arm is connected to the brake shaft, and the other end is connected to a brake cable. The brake cable pulls the rocker arm to swing, so that the brake shaft drives the brake assembly to act for braking. A rocker arm reset member is further provided on the housing. The rocker arm reset member includes a spring and a limiting member. The spring provides a reset force for the rocker arm after braking ends, and the limiting member limits the spring to expand and contract along a straight line direction.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle braking, and particularly to a drum brake mechanism.

Background Art

[0002] The cost of drum brakes is relatively low and the absolute braking force is powerful, so they have been applied to vehicles for nearly a century. The existing drum brakes include a housing, in which two brake pads and a push block are arranged. The push block pushes the brake pads to move outwards and press against the housing for braking. The movement of the push block is generally controlled by a rocker arm and a brake cable connecting the rocker arm. The reset of the rocker arm is generally achieved by setting a spring between its end and the housing to provide an elastic restoring force for the rocker arm. However, since the movement trajectory of the end of the rocker arm is arc-shaped, the spring is prone to damage during the process of stretching and contracting as the rocker arm moves.

Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and propose a drum brake mechanism, which can avoid the internal spring from bending and stretching during braking, reduce spring loss, and has a long service life.

[0004] To solve the above technical problem, the present invention adopts the following technical solutions:

[0005] A drum brake mechanism, comprising a housing, a brake shaft and a brake assembly installed on the housing. A rocker arm is further arranged on the housing. One end of the rocker arm is connected to the brake shaft, and the other end is connected to a brake cable. The brake cable pulls the rocker arm to swing, so that the brake shaft drives the brake assembly to act for braking. A rocker arm reset member is further arranged on the housing. The rocker arm reset member includes a spring and a limiting member. The spring provides a reset force for the rocker arm after braking ends, and the limiting member limits the spring to stretch and contract along a straight line direction.

[0006] Further, the limiting member includes a guide shaft passing through the spring, and the spring stretches and contracts along the axial direction of the guide shaft.

[0007] Further, an adjusting nut is installed on the guide shaft by threaded fit. By adjusting the position of the adjusting nut on the guide shaft, the elastic force of the spring is adjusted.

[0008] Further, the spring is a compression spring or a tension spring.

[0009] Further, the rocker arm reset member further includes a slider slidably installed on the guide shaft for transmitting the acting force between the rocker arm and the spring.

[0010] Further, a chute is arranged on the housing. The guide shaft is installed in the chute. The slider is located in the chute. A transmission part protruding out of the chute is arranged on the slider, and the transmission part abuts against the side part of the rocker arm.

[0011] Further, the contact surface between the transmission part and the rocker arm is a convex arc surface. A limiting groove is further provided on the inner wall of the chute, and a limiting block inserted into the limiting groove is provided on the slider for circumferentially positioning the slider.

[0012] Further, the limiting member includes a sleeve, and the spring is installed inside the sleeve.

[0013] Further, a through groove is provided on the sleeve along the axial direction. The rocker arm passes through the through groove and can swing relative to the sleeve to squeeze the spring during the swinging process.

[0014] Further, a through groove is provided on the sleeve along the axial direction. The rocker arm reset member further includes a slider slidably installed inside the sleeve. The slider abuts against or is connected to the spring. A transmission part extending out of the through groove is provided on the slider, and the transmission part abuts against the rocker arm.

[0015] The beneficial effects of the present invention are as follows:

[0016] For the drum brake mechanism proposed by the present invention, the same as the prior art is that the brake wire controls the braking by swinging the rocker arm. When the rocker arm rotates, it drives the brake shaft to rotate, so as to control the synchronous movement of the brake device through the brake shaft to achieve braking;

[0017] During the braking process, the rocker arm swings, and the center of its swing is located on the axis of the brake shaft. During its swinging process, the spring is driven to move by the rocker arm and stores elastic force at the same time. After the braking stops, the elastic force of the spring is released and acts on the rocker arm to reset the rocker arm. During this process, the contraction and elongation of the spring are limited in the telescopic direction under the action of the limiting member, that is, the spring telescopic in a straight line direction and will not bend, so that the spring is not easily damaged and has a longer service life.

[0018] These features and advantages of the present invention will be detailedly disclosed in the following specific embodiments and drawings.

Description of the Drawings

[0019] The following further describes the present invention with reference to the drawings:

[0020] Figure 1 It is a schematic structural diagram of the drum brake mechanism in the embodiment of the present invention;

[0021] Figure 2 It is a simplified structural diagram of the drum brake mechanism in the embodiment of the present invention;

[0022] Figure 3 It is an exploded view of the drum brake mechanism in the embodiment of the present invention;

[0023] Figure 4 It is another exploded view of the drum brake mechanism in the embodiment of the present invention;

[0024] Figure 5 This is a schematic structural diagram of the rocker arm with a rotating sleeve in the embodiment of the present invention;

[0025] Figure 6 This is the mating diagram A of the rocker arm and the sleeve when the limiting member is a sleeve in the embodiment of the present invention;

[0026] Figure 7 This is the mating diagram B of the rocker arm and the sleeve when the limiting member is a sleeve in the embodiment of the present invention.

[0027] Reference numerals:

[0028] Outer shell 100, brake shaft 110, brake assembly 120;

[0029] Rocker arm 200, rotating groove 210;

[0030] Spring 300;

[0031] Guide shaft 400, adjusting nut 410, hexagon nut 420, annular groove 430;

[0032] Slider 500, transmission part 510, limiting block 520;

[0033] Mounting part 600, sliding groove 610, limiting groove 620, rotating hole 630, pin 640, sleeve 650, through

[0034] groove 651, through hole 660;

[0035] Rotating sleeve 700.

Detailed implementation manners

[0036] The technical solutions of the embodiments of the present invention will be explained and described below with reference to the accompanying drawings of the embodiments of the present invention. However, the following embodiments are only the preferred embodiments of the present invention and not all of them. Based on the embodiments in the implementation manners, other embodiments obtained by those skilled in the art without creative efforts all fall within the protection scope of the present invention.

[0037] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0038] In addition, 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 quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more, unless otherwise clearly defined.

[0039] In the present invention, unless otherwise clearly specified and defined, terms such as "mounted", "connected", "coupled", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0041] Referring to Figures 1 to 4 , an embodiment of the present invention discloses a drum brake mechanism, which includes a housing 100, a brake shaft 110 mounted on the housing 100, and a brake assembly 120. A rocker arm 200 is further provided on the housing 100. One end of the rocker arm 200 is connected to the brake shaft 110, and the other end is connected to a brake cable. The brake cable pulls the rocker arm 200 to swing, so that the brake shaft 110 drives the brake assembly 120 to act for braking. A rocker arm return member is further provided on the housing 100. The rocker arm return member includes a spring 300 and a limiting member. The spring 300 provides a return force for the rocker arm 200 after braking ends, and the limiting member limits the spring 300 to expand and contract along a straight line direction.

[0042] The same as the prior art, the brake assembly 120 includes a brake wheel and rollers provided on the brake shaft 110. A brake shoe is further provided inside the housing 100. During braking, the brake cable pulls the rocker arm 200 to swing. When the rocker arm 200 rotates, it drives the brake shaft 110 and the brake wheel on the brake shaft 110 to rotate. The brake wheel causes the rollers to push the brake shoe, thereby achieving braking.

[0043] During the braking process, the rocker arm 200 swings, and the center of its swing is located on the axis of the brake shaft 110. During its swing, the spring 300 is driven by the rocker arm 200 to move and accumulate elastic force at the same time. After braking stops, the elastic force of the spring 300 is released and acts on the rocker arm 200 to reset the rocker arm 200. During this process, the contraction and elongation of the spring 300 are limited in the telescopic direction by the limiting member, that is, the spring 300 telescopes in a straight line direction and will not bend, making the spring 300 not easily damaged and having a longer service life.

[0044] Preferably, the limiting member includes a guide shaft 400, and the spring 300 is sleeved on the guide shaft 400. Under the limitation of the guide shaft 400, the spring 300 can telescopically along the axial direction of the guide shaft 400, so that the telescopic direction is limited, and the spring 300 cannot bend and the radial displacement is limited, ensuring that the movement track of the spring 300 is a straight line.

[0045] Since the spring 300 is sleeved on the guide shaft 400, it cannot be guaranteed that the rocker arm 200 can maintain contact with the spring 300 during the swing process. In order to facilitate the transmission of the force between the rocker arm 200 and the spring 300, the rocker arm reset member further includes a slider 500. The slider 500 is slidably installed on the guide shaft 400. The slider 500 abuts against the side of the rocker arm 200 and at the same time abuts against or is connected to the end of the spring 300, and is used to transmit the thrust of the rocker arm 200 on the spring 300 and the elastic force of the spring 300 on the rocker arm 200. When the rocker arm 200 is pulled by the brake wire and swings, it can push the slider 500 to move. When the slider 500 moves, it drives the spring 300 to change synchronously to accumulate elastic force. After braking ends, the elastic force of the spring 300 acts on the rocker arm 200 through the slider 500 to drive the rocker arm 200 to reset. With the slider 500 as the force conduction component between the rocker arm 200 and the spring 300, it can avoid the drum brake from getting stuck due to accidents and being unable to brake normally.

[0046] Preferably, the spring 300 is a compression spring. One side of the slider 500 abuts against the spring 300, and the other side abuts against the rocker arm 200, and can accumulate elastic force when compressed. After elongation, the elastic force accumulated by the spring 300 can be released and act on the rocker arm 200. In addition, the spring can also be a tension spring. If the spring is a tension spring, it needs to be connected to the slider. One side of the slider is connected to the spring and at the same time abuts against the rocker arm. When the rocker arm swings, it drives the tension spring to elongate. When the tension spring resets, it drives the slider and the rocker arm to reset.

[0047] Furthermore, an installation part 600 is provided on the side of the housing 100. A chute 610 is provided on the installation part 600. The guide shaft 400 is arranged in the chute 610. The slider 500 and the spring 300 are both located in the chute 610, thus preventing the spring 300 and the slider 500 from being accidentally touched and affecting the normal function of the drum brake.

[0048] In order for the slider 500 to cooperate with the rocker arm 200, it needs to extend out of the chute 610 and then contact the rocker arm 200. Therefore, the slider 500 includes a transmission part 510 provided with an extension out of the chute 610. After the transmission part 510 extends out of the chute 610, it abuts against the side of the rocker arm 200. When the rocker arm 200 swings, the slider 500 can be pushed to squeeze the spring 300 by pushing the transmission part 510. In order to reduce the friction between the rocker arm 200 and the transmission part 510 during the swinging process, the end face of the transmission part 510 is a convex arc surface. The contact between the arc surface and the rocker arm 200 is surface and line contact, with less wear between the two and smoother transmission. In addition, the transmission part can also be rotatably installed on the slider. In this way, during the swinging of the rocker arm, the frictional force between the two can be converted into the power for the transmission part to rotate relative to the slider itself, so as to reduce the generation of frictional force. In addition, the slider and the transmission part can also be in inclined plane mating transmission.

[0049] Since the contact surface between the transmission part 510 and the rocker arm 200 is a convex arc surface, during the swinging process of the rocker arm 200, the rocker arm 200 will exert a thrust in the radial direction of the guide shaft 400 on the transmission part 510, which will cause the slider 500 to rotate relative to the guide shaft 400 and the transmission part 510 to disengage from the rocker arm 200. In this way, the rocker arm 200 cannot be reset. There is also a limiting groove 620 in the chute 610, and a limiting block 520 inserted into the limiting groove 620 is provided on the slider 500 to limit the circumferential movement of the slider 500. In this way, the transmission part 510 can be kept in contact with the rocker arm 200 and will not push the slider 500 to rotate around the guide shaft 400 during the swinging process of the rocker arm 200.

[0050] Refer to Figures 1 to 4 As shown in, the force required for the reset of the rocker arm 200 is provided by the spring 300. If the elastic force of the spring 300 is insufficient, the rocker arm 200 cannot be fully reset, which will cause the drum brake to still have a certain braking ability, affecting driving, and the wear of the drum brake will be very large. When the length of the spring 300 is a certain value, the greater the degree of compression, the greater the elastic force. Based on the above embodiment, in another embodiment of the present invention, without replacing the spring 300, the elastic force of the spring 300 can be changed by adjusting the length of the spring 300. Specifically, there is a section of external thread on the guide shaft 400 and an adjusting nut 410 threadedly fitted on the guide shaft 400. One end of the spring 300 abuts against the slider 500, and the other end abuts against the adjusting nut 410. Rotating the adjusting nut 410 can make the adjusting nut 410 move on the guide shaft 400 and adjust the distance between it and the slider 500, thereby changing the length of the spring 300 between the two.

[0051] When it is necessary to increase the elastic force of the spring 300, the distance between the slider 500 and the adjusting nut 410 can be shortened. When it is necessary to reduce the elastic force of the spring 300, the distance between the slider 500 and the adjusting nut 410 can be increased.

[0052] Referring to Figures 1 to 4 , further, based on the above embodiments, in another embodiment of the present invention, in order to facilitate the rotation of the adjusting nut 410, the guide shaft 400 is rotatably mounted on the mounting portion 600. The side surface of the adjusting nut 410 abuts against the side wall of the sliding groove 610. By rotating the guide shaft 400, the adjusting nut 410 is moved along the guide shaft 400. The sliding groove 610 can limit the rotation of the adjusting nut 410 by cooperating with the adjusting nut 410. When the guide shaft 400 rotates, the adjusting nut 410 remains circumferentially stationary and can move axially along the guide shaft 400. In this way, only by rotating the guide shaft 400 can the adjustment be carried out, and there is no need to disassemble and assemble the guide shaft 400.

[0053] In order to facilitate the rotation of the guide shaft 400, a rotation hole 630 is provided on the inner wall of the sliding groove 610. One end of the guide shaft 400 is inserted into the rotation hole 630, and the other end extends out of the sliding groove 610 and is fixedly installed with a hexagonal nut 420. When it is necessary to rotate the guide shaft 400, just rotate the hexagonal nut 420, which is relatively convenient.

[0054] In order to facilitate the installation of the guide shaft 400, the guide shaft 400 is arranged to be inserted and installed on the mounting portion 600. During installation, first insert the guide shaft 400 into the mounting portion 600, then sequentially install the slider 500, the spring 300 and the adjusting nut 410 at its end, and then insert the end portion into the rotation hole 630 to complete the installation.

[0055] Referring to Figures 1 to 4 , based on the above embodiments, the guide shaft 400 has a tendency to move axially when the slider 500 slides. Therefore, it is necessary to axially limit the guide shaft 400. In another embodiment of the present invention, a pin 640 is provided on the mounting portion 600 and arranged radially along the guide shaft 400. The pin 640 can abut against the guide shaft 400 to limit the axial displacement of the guide shaft 400. In this way, the axis of the guide shaft 400 is limited and there will be no axial change during the braking process.

[0056] In order to prevent the pin 640 from affecting the rotation of the guide shaft 400, a circumferential inward depression is formed on the guide shaft 400 to form an annular groove 430. The pin 640 is snapped into the annular groove 430. Through the cooperation of the annular groove 430 and the pin 640, the guide shaft 400 will not collide with the pin 640 when rotating. When the guide shaft 400 moves axially, the side wall of the guide shaft 400 abuts against the pin 640 to limit the axial movement of the guide shaft 400.

[0057] Referring to Figure 5, different from the above embodiments, in another embodiment of the present invention, a rotating sleeve 700 is slidably mounted on the rocker arm 200. The rotating sleeve 700 can rotate relative to the rocker arm 200. The guide shaft 400 can limit the rotation of the rotating sleeve 700 relative to the guide shaft 400. In this way, as the rocker arm 200 swings, the rotating sleeve 700 can rotate relative to the rocker arm 200 and slide along the guide shaft 400. At the same time, the rotating sleeve 700 also slides on the rocker arm 200.

[0058] Refer to Figure 6 and Figure 7 , different from the above embodiments, in another embodiment of the present invention, the limiting member is a sleeve 650, and the spring 300 is installed inside the sleeve 650.

[0059] The sleeve 650 can limit the radial movement of the spring 300, thereby avoiding the spring 300 bending to the side when contracting.

[0060] Specifically, in order to enable the rocker arm 200 to smoothly push the spring 300, a through groove 651 is provided on the sleeve 650 along the axial direction. The rocker arm 200 passes through the through groove 651 and can swing relative to the sleeve 650 to squeeze the spring 300 during the swinging process. During the braking process, the rocker arm 200 swings relative to the spring 300 and moves relative to the through groove 651 at the same time. Under the action of the through groove 651, the sleeve 650 does not limit the swinging of the rocker arm 200, and the rocker arm 200 can also squeeze the spring 300 during the swinging process, and the through groove 651 does not cause the spring 300 to have a tendency to bend.

[0061] Alternatively, a slider 500 is slidably mounted inside the sleeve 650. The slider 500 abuts against the spring 300. The slider 500 includes a transmission portion 510 that extends out of the through groove 651. The transmission portion 510 abuts against the rocker arm 200. In this way, when the rocker arm 200 swings, it can move the slider 500 through contact with the transmission portion 510 and squeeze the spring 300 at the same time, and the same technical effect can also be achieved.

[0062] Refer to Figures 1 to 4 , in another embodiment of the present invention, a through hole 660 is further provided on the mounting portion 600. A rotating groove 210 is provided on the rocker arm 200. A rotating portion (not shown in the figure) is rotatably mounted in the rotating groove 210. The brake wire passes through the through hole 660 and is connected to the rotating portion. With this setting, when the brake wire pulls the rocker arm 200 to swing, the rotating member can rotate relative to the rocker arm 200 to avoid the brake wire bending.

[0063] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes but is not limited to the content described in the drawings and the above specific implementation manner. Any modification that does not deviate from the functional and structural principles of the present invention will be included in the scope of the claims.

Claims

1. Drum brake mechanism, comprising a housing, a brake shaft mounted on the housing, and a brake assembly. A rocker arm is further provided on the housing. One end of the rocker arm is connected to the brake shaft, and the other end is connected to a brake cable. The brake cable pulls the rocker arm to swing, so that the brake shaft drives the brake assembly to act for braking. Characterized in that, A rocker arm reset member is further provided on the housing. The rocker arm reset member includes a spring and a limiting member. The spring provides a reset force for the rocker arm after braking ends, and the limiting member limits the spring to expand and contract along a straight line direction; the limiting member includes a sleeve, and the spring is installed in the sleeve; A through groove is provided on the sleeve along the axial direction. The rocker arm reset member further includes a slider slidably installed in the sleeve. The slider abuts or is connected to the spring. A transmission portion extending out of the through groove is provided on the slider, and the transmission portion abuts against the rocker arm. The through groove does not cause the spring to have a tendency to bend.

2. The drum brake mechanism according to claim 1, Characterized in that, The limiting member includes a guide shaft penetrating through the spring, and the spring expands and contracts along the axial direction of the guide shaft.

3. The drum brake mechanism according to claim 2, Characterized in that, An adjusting nut is installed on the guide shaft by threaded fit. By adjusting the position of the adjusting nut on the guide shaft, the elastic force of the spring is adjusted.

4. The drum brake mechanism according to claim 2, Characterized in that, The spring is a compression spring or a tension spring.

5. The drum brake mechanism according to claim 2, Characterized in that, The rocker arm reset member further includes a slider slidably installed on the guide shaft for transmitting the acting force between the rocker arm and the spring.

6. The drum brake mechanism according to claim 5, Characterized in that, A chute is provided on the housing. The guide shaft is installed in the chute. The slider is located in the chute. A transmission portion extending out of the chute is provided on the slider, and the transmission portion abuts against the side portion of the rocker arm.

7. The drum brake mechanism according to claim 6, Characterized in that, The contact surface between the transmission portion and the rocker arm is a convex arc surface. A limiting groove is further provided on the inner wall of the chute. A limiting block inserted into the limiting groove is provided on the slider for circumferentially positioning the slider.

8. The drum brake mechanism according to claim 1, Characterized in that, A through groove is provided on the sleeve along the axial direction. The rocker arm penetrates through the through groove and can swing relative to the sleeve to squeeze the spring during the swinging process.

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