CN117570133A - An adjustable drum brake for electric vehicles - Google Patents

Abstract

An adjustable drum brake for an electric vehicle belongs to the technical field of drum brakes, and aims to solve the technical problems that the existing drum brake is easy to accumulate heat and has potential safety hazards when the electric vehicle brakes for many times on long downhill; according to the invention, through the arrangement of the air inlet component, the sealing component, the supporting component, the transmission component, the centrifugal rotating component and the blowing component, in the braking process, the embedded rod can be inserted into the embedded hole, so that the face gear and the outer tooth ring are rotated, the brake shoe and the brake pad can be radiated through the rotation of the fan, meanwhile, the internal and external air can circulate through the air inlet hopper, the ventilation pipe and the communication hole, the heat of the brake shoe and the brake pad can be taken away, after the downhill is finished, the angle of the spur gear can be adjusted under the dead weight of the balancing weight, the ventilation pipe can be sealed, the radiation of the brake pad in the long downhill can be realized, the reduction of the braking effect can be avoided, and the safety can be improved.

Description

An adjustable drum brake for electric vehicles

Technical field

The present invention relates to the technical field of drum brakes, and in particular to an adjustable drum brake for electric vehicles.

Background technique

Drum brakes are also called block brakes. Through the braking transmission mechanism, the brake shoes press the brake friction pads against the inside of the brake drum, thereby generating braking force to decelerate the wheels or stop the wheels in the shortest distance as needed. To ensure driving safety, when the existing drum brake is used, due to structural limitations, it is difficult to dissipate heat. When an electric vehicle is traveling downhill for a long time, it needs to brake multiple times. When braking multiple times, the drum brake Heat accumulation is easy to occur inside, causing the temperature of the brake pads inside the drum brake to be too high, resulting in a decrease in the braking effect of the drum brake, posing a safety hazard.

Contents of the invention

The object of the present invention is to provide an adjustable drum brake for electric vehicles, which can solve the problem in the above-mentioned background technology that existing drum brakes are prone to heat accumulation and pose safety risks when electric vehicles brake multiple times on long downhill slopes. The problem.

In order to achieve the above object, the present invention provides the following technical solution: an adjustable drum brake for electric vehicles, including a brake base plate and a brake drum embedded on one side of the brake base plate, and the brake drum and the brake base plate are not In contact with each other, a camshaft is rotatably connected to both sides of the brake base plate. One end of the camshaft is fixedly connected to a rocker arm. The inner wall of the brake base plate is provided with braking components for braking and heat dissipation components for heat dissipation. The brake base plate An air intake adjustment component for adjusting the air intake is embedded in the outer surface;

The air intake adjustment assembly includes an air intake component embedded in the outer surface of the brake base plate and a closing component disposed on one side of the brake assembly. The closing component is disposed on one side of the air intake component. The heat dissipation assembly includes an air intake component disposed on the brake base plate. The support part of the inner wall and the transmission part provided on the outer surface of the support part. The outer surface of the support part is embedded with a centrifugal rotating part. A blowing part is provided between the transmission part and the inner wall of the brake bottom plate, and there are multiple sets of blowing parts. The centrifugal rotation part is One end of the component is connected to the inner wall of the brake drum. The air inlet component is used to connect the inside and outside of the brake bottom plate. The closing component is used to control the air intake of the air inlet component. The centrifugal rotating component is used for transmission so that the brake drum can drive the support component to rotate. The component is used to support the transmission component and drive the transmission component to rotate. The transmission component is used to drive multiple groups of blowing components to rotate to generate airflow.

Further, the air inlet component includes a first support block fixedly connected to the outer surface of the brake base plate and an air inlet bucket fixedly connected to the upper end of the first support block. One end of the air inlet bucket is fixedly connected to a ventilation pipe, and one end of the ventilation pipe is connected to the upper end of the first support block. The outer surface of the brake base plate is embedded and fixedly connected, the outer surface of the ventilation pipe is fixedly connected with a second support block, and the air inlet bucket and ventilation pipe are used for gas circulation.

Further, the brake assembly includes a positioning block fixedly connected to the inner wall of the brake bottom plate. The lower end of the second support block is fixedly connected to the upper end of the positioning block. Both ends of the positioning block are rotatably connected with brake shoes. The two sets of brakes One end of the moving shoe is in contact with the camshaft. The outer surfaces of the two sets of brake shoes are fixedly connected with brake pads. The two sets of brake pads match the position of the brake drum. The two sets of brake shoes are A return spring is fixedly arranged between them, and the return spring is used to pull the brake shoes of the two groups to reset.

Further, the closing component includes a rotating shaft that is rotatably connected to one side of the positioning block and a spur gear that is fixedly connected to one end of the rotating shaft. Arc holes are penetrated on both sides of the spur gear, and one side of the spur gear is in contact with one end of the ventilation pipe. , and the arc hole matches the position of the ventilation pipe, and the spur gear is used to control the air outlet of the ventilation pipe.

Further, the support component includes a support ring fixedly connected to the inner wall of the brake bottom plate and an embedded ring that is embedded and rotationally connected to one end of the support ring. The other end of the embedded ring is fixedly connected to a fixed disk, and the support ring is used to support the embedded ring.

Further, the transmission component includes an end gear fixedly connected to the outer surface of the fixed plate and an external gear ring fixedly connected to one side of the end gear, and the external gear ring is meshed with the spur gear, and a counterweight is fixedly connected to the lowest position inside the external gear ring. Block, counterweight block is used to control the angle of the spur gear.

Further, the centrifugal rotating component includes a connecting ring fixedly connected to the inner wall of the brake drum and a rotating ring fixedly connected to the other end of the connecting ring. A mounting hole is provided on the inside of the rotating ring, and a pressure spring is fixedly connected to the inner wall of the mounting hole. The other end of the pressure spring An embedded rod is fixedly connected, and the embedded rod is movablely connected to the mounting hole. The mounting holes, pressure springs and embedded rods are arranged in four groups evenly in an annular shape, and the pressure spring is used to squeeze the embedded rod to move.

Further, one end of the fixed plate is fixedly connected to a transmission ring, and the outer surface of the transmission ring is provided with embedded holes, and the embedded holes are evenly arranged in four groups in an annular shape. The four groups of embedded rods are respectively connected with the four groups of embedded holes. Movable fitting, the embedded rod is used to drive the transmission ring to rotate.

Further, the blowing component includes a positioning plate fixedly connected to the inner wall of the brake bottom plate and a transmission shaft rotatably connected to one side of the positioning plate. A helical gear and a fan are fixedly connected to the outer surface of the transmission shaft at intervals, and the helical gear is meshed with the end face gear. The face gear is used to drive the fan to rotate.

Furthermore, the outer surface of the brake pad is configured as a convex arc, and the inner wall of the brake drum is provided with a fitting groove, and the fitting groove matches the curvature of the outer surface of the brake pad, and the fitting groove is used to expand the contact area.

Compared with the prior art, the beneficial effects of the present invention are:

The invention proposes an adjustable drum brake for electric vehicles. Through the arrangement of air inlet parts, closing parts, supporting parts, transmission parts, centrifugal rotating parts and blowing parts, during the braking process, the embedding rod will be inserted into the embedding hole. Internally, both the end gear and the external toothed ring rotate. The rotation of the fan can dissipate heat to the brake shoes and brake pads. At the same time, the internal and external air can circulate through the air inlet duct, ventilation duct and communication hole, and can take away the brake shoes. and the heat of the brake pads. After the downhill, the angle of the spur gear can be adjusted under the action of the weight of the counterweight, and the ventilation pipe can be closed, which can dissipate the heat of the brake pads during long downhills, thus avoiding braking. The effect is reduced and safety can be improved.

Description of the drawings

Figure 1 is a schematic diagram of the overall three-dimensional structure of the present invention;

Figure 2 is a schematic structural diagram of the air intake adjustment assembly, heat dissipation assembly, camshaft and brake assembly of the present invention;

Figure 3 is a schematic structural diagram of the brake assembly and brake base plate of the present invention;

Figure 4 is an exploded schematic diagram of the structure of the air inlet component and the closing component of the present invention;

Figure 5 is a schematic structural diagram of the heat dissipation assembly and spur gear of the present invention;

Figure 6 is a schematic structural diagram of the support component and transmission component of the present invention;

Figure 7 is an exploded schematic diagram of the structure of the support component and transmission component of the present invention;

Figure 8 is a schematic structural diagram of the centrifugal rotating component of the present invention;

Figure 9 is a schematic diagram of the internal structure of the rotating ring of the present invention;

Figure 10 is a schematic structural diagram of the blowing component of the present invention;

Figure 11 is a structural cross-sectional view of the brake drum and brake pad of the present invention.

In the picture: 1. Brake drum; 11. Fitting groove; 2. Brake base plate; 21. Communication hole; 3. Rocker arm; 4. Air intake adjustment component; 41. Air intake parts; 411. First support block ; 412. Air intake bucket; 413. Ventilation duct; 414. Second support block; 42. Closing component; 421. Rotating shaft; 422. Spur gear; 423. Arc hole; 5. Heat dissipation component; 51. Support component; 511. Support ring; 512. Embedded ring; 513. Fixed plate; 514. Transmission ring; 515. Embedded hole; 52. Transmission parts; 521. Face gear; 522. External gear ring; 523. Counterweight; 53. Centrifugal Rotating parts; 531, connecting ring; 532, rotating ring; 533, mounting hole; 534, pressure spring; 535, embedded rod; 54, blowing parts; 541, positioning plate; 542, transmission shaft; 543, helical gear; 544. Fan; 6. Camshaft; 7. Brake assembly; 71. Positioning block; 72. Brake shoe; 73. Brake pad; 74. Return spring.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

As shown in Figures 1, 2 and 5, an adjustable drum brake for electric vehicles includes a brake base plate 2 and a brake drum 1 embedded in one side of the brake base plate 2, and the brake drum 1 and The brake base plate 2 does not contact. A camshaft 6 is rotatably connected to both sides of the brake base plate 2. One end of the camshaft 6 is fixedly connected to a rocker arm 3. The inner wall of the brake base plate 2 is provided with brake assemblies 7 and brake components for braking at intervals. For the heat dissipation component 5, the outer surface of the brake base plate 2 is embedded with an air intake adjustment component 4 for adjusting the air intake;

The air intake adjustment assembly 4 includes an air intake component 41 embedded in the outer surface of the brake base plate 2 and a closing component 42 disposed on one side of the brake assembly 7 , and the closing component 42 is disposed on one side of the air intake component 41 , and the heat dissipation component 5 It includes a support member 51 provided on the inner wall of the brake base plate 2 and a transmission member 52 provided on the outer surface of the support member 51. A centrifugal rotating member 53 is embedded in the outer surface of the support member 51, and is provided between the transmission member 52 and the inner wall of the brake base plate 2. There are blowing parts 54, and there are multiple sets of blowing parts 54. One end of the centrifugal rotating part 53 is connected to the inner wall of the brake drum 1. The air inlet part 41 is used to communicate the inside and outside of the brake base plate 2, and the closing part 42 is used to control the air inlet part. 41 air intake, the centrifugal rotating component 53 is used for transmission so that the brake drum 1 can drive the supporting component 51 to rotate. The supporting component 51 is used to support the transmission component 52 and drive the transmission component 52 to rotate. The transmission component 52 is used to drive multiple groups of blowers. The component 54 rotates thereby creating an air flow.

The present invention will be further described below in conjunction with examples.

Referring to Figures 3, 4 and 6-11, the air inlet component 41 includes a first support block 411 fixedly connected to the outer surface of the brake base plate 2 and an air inlet bucket 412 fixedly connected to the upper end of the first support block 411. One end of the air inlet bucket 412 is fixedly connected to a ventilation pipe 413. One end of the ventilation pipe 413 is embedded and fixedly connected to the outer surface of the brake base plate 2. The outer surface of the ventilation pipe 413 is fixedly connected to a second support block 414. The air intake bucket 412 and the ventilation pipe 413 are used for For gas circulation, the air intake range can be expanded through the air intake bucket 412.

The brake assembly 7 includes a positioning block 71 fixedly connected to the inner wall of the brake bottom plate 2. The lower end of the second support block 414 is fixedly connected to the upper end of the positioning block 71. Both ends of the positioning block 71 are rotatably connected with brake shoes 72. The two sets of brakes One end of the moving shoe 72 is arranged in contact with the camshaft 6. The outer surfaces of the brake shoes 72 of the two groups are fixedly connected with brake pads 73. The brake pads 73 of the two groups match the position of the brake drum 1. The brake shoes of the two groups A return spring 74 is fixedly arranged between the two groups of brake shoes 72 . The return spring 74 is used to pull the two groups of brake shoes 72 to reset. The rotation of the camshaft 6 can push the two groups of brake shoes 72 away from each other, so that the two groups of brake pads 73 It is in contact with the inner wall of the brake drum 1 to achieve braking, and the return spring 74 can achieve the reset of the two sets of brake shoes 72 .

The closing component 42 includes a rotating shaft 421 rotatably connected to one side of the positioning block 71 and a spur gear 422 fixedly connected to one end of the rotating shaft 421. Arc holes 423 are formed on both sides of the spur gear 422. One side of the spur gear 422 is connected to the ventilation pipe. 413 is set in contact with one end, and the arc hole 423 matches the position of the ventilation pipe 413. The spur gear 422 is used to control the air outlet of the ventilation pipe 413. When the spur gear 422 rotates so that the ventilation pipe 413 coincides with the arc hole 423, the ventilation pipe 413 The gas in the brake base plate 2 can enter the interior of the brake base plate 2 through the arc hole 423, and conversely, the end of the ventilation pipe 413 can be sealed.

The support component 51 includes a support ring 511 fixedly connected to the inner wall of the brake base plate 2 and an embedded ring 512 that is embedded and rotationally connected to one end of the support ring 511. The other end of the embedded ring 512 is fixedly connected to a fixed disk 513. The support ring 511 is used to support the embedded ring. 512.

The transmission component 52 includes an end gear 521 fixedly connected to the outer surface of the fixed plate 513 and an external toothed ring 522 fixedly connected to one side of the end gear 521, and the external toothed ring 522 is meshed with the spur gear 422, and the lowest inner part of the external toothed ring 522 A counterweight block 523 is fixedly connected. The counterweight block 523 is used to control the angle of the spur gear 422. When the external gear ring 522 is not subject to external force, the counterweight block 523 will drive the external gear ring 522 to rotate due to its own weight, so that the counterweight block 523 It is located at the lowest part of the inner wall of the external toothed ring 522. During this process, the external toothed ring 522 will drive the spur gear 422 to rotate, so that the spur gear 422 stops at a fixed angle. At this time, the spur gear 422 seals one end of the ventilation pipe 413.

The centrifugal rotating component 53 includes a connecting ring 531 fixedly connected to the inner wall of the brake drum 1 and a rotating ring 532 fixedly connected to the other end of the connecting ring 531. A mounting hole 533 is provided inside the rotating ring 532, and a pressure spring is fixedly connected to the inner wall of the mounting hole 533. 534, the other end of the pressure spring 534 is fixedly connected with an embedded rod 535, and the embedded rod 535 is embedded and movable connected with the mounting hole 533. The mounting hole 533, the pressure spring 534 and the embedded rod 535 are all arranged in four groups in an annular shape. The pressure spring 534 is As the squeezing and embedding rods 535 move, when the electric vehicle is running, the brake drum 1 will rotate with the wheels of the electric vehicle, causing both the connecting ring 531 and the rotating ring 532 to rotate, causing the four groups of embedding rods 535 to also rotate. Since the rotation speed is faster, the When the rotating ring 532 rotates faster, the embedded rod 535 can overcome the elastic force of the pressure spring 534 and move toward the inside of the mounting hole 533. When the electric vehicle is braked, due to the rotation of the rotating ring 532 At a slower speed, the pressure spring 534 can press the embedded rod 535 to move out of the mounting hole 533 .

One end of the fixed plate 513 is fixedly connected to a transmission ring 514. The outer surface of the transmission ring 514 is provided with embedding holes 515, and the embedding holes 515 are evenly provided with four groups in an annular shape. The four groups of embedding rods 535 are movablely embedded with the four groups of embedding holes 515 respectively. The embedded rods 535 are used to drive the transmission ring 514 to rotate. When the electric vehicle brakes, the four sets of embedded rods 535 will be squeezed to fit the outer surface of the transmission ring 514, because the electric vehicle wheels will still rotate during the braking process. , during this process, when the embedding hole 515 and the embedding rod 535 coincide, the embedding rod 535 will be inserted into the embedding hole 515, so that the transmission ring 514 rotates together with the rotating ring 532. When the transmission ring 514 rotates, it can be driven by the fixed plate 513 The face gear 521 also rotates.

The blowing component 54 includes a positioning plate 541 fixedly connected to the inner wall of the brake base plate 2 and a transmission shaft 542 rotatably connected to one side of the positioning plate 541. A helical gear 543 and a fan 544 are fixedly connected to the outer surface of the transmission shaft 542 at intervals, and the helical gear 543 It is meshed with the end gear 521. The end gear 521 is used to drive the fan 544 to rotate. When the end gear 521 rotates, it can drive multiple sets of helical gears 543 to rotate, so that the transmission shaft 542 drives the fan 544 to rotate. When the fan 544 rotates, it can produce blowing direction. The airflow of the brake shoe 72 can reduce the temperature of the brake shoe 72 and the brake pad 73 .

The outer surface of the brake pad 73 is set as a convex arc, and the inner wall of the brake drum 1 is provided with a fitting groove 11, and the fitting groove 11 matches the curvature of the outer surface of the brake pad 73. The fitting groove 11 is used to expand the contact area, and the fitting groove 11 is used to expand the contact area. The groove 11 and the brake pad 73 are arranged in an arc shape, which can increase the contact area between the brake pad 73 and the fitting groove 11, increase the friction force, and thus improve the braking effect.

When the electric vehicle is continuously braking on a long downhill slope, the two sets of brake pads 73 will rub against the fitting groove 11 to achieve braking. During the braking process, the embedding rod 535 will be inserted into the embedding hole 515, so that the end gear 521 and the external gear ring 522 both rotate. When the end gear 521 rotates, it will drive multiple sets of fans 544 to rotate. The rotation of the multiple sets of fans 544 can generate airflow that blows to the two sets of brake shoes 72, which can improve the braking performance. The shoe 72 and the brake pad 73 dissipate heat. When the external gear ring 522 rotates, the spur gear 422 will also rotate. During the rotation of the spur gear 422, since the electric vehicle is traveling slowly downhill, the internal and external air can pass through the air intake bucket 412 and the ventilation pipe. 413 and the communication hole 21 communicate, and the heat of the brake shoe 72 and the brake pad 73 can be taken away through the circulation of air. At the same time, the resistance when the embedded rod 535 drives the transmission ring 514 to rotate can improve a certain braking effect. After the downhill is completed, As the speed of the electric vehicle increases, when the rotation speed of the rotating ring 532 exceeds a certain value, the embedded rod 535 will be separated from the embedded hole 515 due to centrifugal force, and the spur gear 422 can be adjusted to be in contact with the ventilation under the self-weight of the counterweight 523 The position where the pipe 413 contacts, the ventilation pipe 413 can be closed, which can effectively reduce the dust entering between the brake drum 1 and the brake bottom plate 2 when the electric vehicle is driving, and can realize the heat dissipation of the brake pad 73 when going downhill for a long time. This can avoid the decline in braking effect and improve safety. At the same time, it can automatically start and end heat dissipation following the braking situation of the electric vehicle, making it easy to use.

It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that these entities or operations are mutually exclusive. any such actual relationship or sequence exists between them. Furthermore, the terms "comprises," "comprises," or any other variations thereof are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that includes a list of elements includes not only those elements, but also those not expressly listed other elements, or elements inherent to the process, method, article or equipment.

The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technical field can, within the technical scope disclosed in the present invention, implement the technical solutions of the present invention. Equivalent substitutions or changes of the inventive concept thereof shall be included in the protection scope of the present invention.

Claims (10)

1. The utility model provides a drum brake with adjustable electric motor car, includes brake pad (2) and embedding setting brake drum (1) in brake pad (2) one side, and brake drum (1) and brake pad (2) contactless, and brake pad (2) both sides run through and rotate and be connected with camshaft (6), camshaft (6) one end fixedly connected with rocking arm (3), its characterized in that: a braking component (7) for braking and a heat dissipation component (5) for dissipating heat are arranged on the inner wall of the braking bottom plate (2) at intervals, and an air inlet adjusting component (4) for adjusting air inlet is embedded into the outer surface of the braking bottom plate (2);

the air inlet adjusting assembly (4) comprises an air inlet part (41) embedded in the outer surface of the brake bottom plate (2) and a sealing part (42) arranged on one side of the brake assembly (7), the sealing part (42) is arranged on one side of the air inlet part (41), the heat dissipation assembly (5) comprises a supporting part (51) arranged on the inner wall of the brake bottom plate (2) and a transmission part (52) arranged on the outer surface of the supporting part (51), a centrifugal rotating part (53) is embedded in the outer surface of the supporting part (51), an air blowing part (54) is arranged between the transmission part (52) and the inner wall of the brake bottom plate (2), the air blowing part (54) is provided with a plurality of groups, one end of the centrifugal rotating part (53) is connected with the inner wall of the brake drum (1), the air inlet part (41) is used for communicating the inner side with the brake bottom plate (2), the sealing part (42) is used for controlling air inlet of the air inlet part (41), the centrifugal rotating part (53) is used for driving the brake drum (1) to rotate the supporting part (51), the supporting part (52) is used for supporting the transmission part (52) and driving the transmission part (52) to rotate, and the transmission part (52) is used for driving the transmission part (52) to rotate, and the transmission part (52) is driven to rotate, and the air flow is driven to rotate.

2. An adjustable drum brake for an electric vehicle as set forth in claim 1, wherein: the air inlet component (41) comprises a first supporting block (411) fixedly connected to the outer surface of the brake bottom plate (2) and an air inlet hopper (412) fixedly connected to the upper end of the first supporting block (411), one end of the air inlet hopper (412) is fixedly connected with a ventilation pipe (413), one end of the ventilation pipe (413) is fixedly connected with the outer surface of the brake bottom plate (2) in an embedded mode, the outer surface of the ventilation pipe (413) is fixedly connected with a second supporting block (414), and the air inlet hopper (412) and the ventilation pipe (413) are used for air circulation.

3. An adjustable drum brake for an electric vehicle as claimed in claim 2, wherein: the brake assembly (7) comprises a positioning block (71) fixedly connected to the inner wall of a brake bottom plate (2), the lower end of a second supporting block (414) is fixedly connected with the upper end of the positioning block (71), two groups of brake shoes (72) are rotatably connected to two ends of the positioning block (71), one ends of the two groups of brake shoes (72) are in contact with a cam shaft (6), the outer surfaces of the two groups of brake shoes (72) are fixedly connected with brake pads (73), the two groups of brake pads (73) are matched with the positions of a brake drum (1), return springs (74) are fixedly arranged between the two groups of brake shoes (72), and the return springs (74) are used for pulling the two groups of brake shoes (72) to return.

4. An adjustable drum brake for electric vehicles according to claim 3, wherein: the sealing component (42) comprises a rotating shaft (421) which is rotationally connected with one side of the positioning block (71) and a straight gear (422) which is fixedly connected with one end of the rotating shaft (421), wherein arc-shaped holes (423) are formed in the two sides of the straight gear (422) in a penetrating mode, one side of the straight gear (422) is in contact with one end of the ventilation pipe (413), the arc-shaped holes (423) are matched with the position of the ventilation pipe (413), and the straight gear (422) is used for controlling air outlet of the ventilation pipe (413).

5. An adjustable drum brake for an electric vehicle as set forth in claim 4, wherein: the supporting component (51) comprises a supporting ring (511) fixedly connected to the inner wall of the brake bottom plate (2) and an embedded ring (512) which is embedded and rotatably connected with one end of the supporting ring (511), the other end of the embedded ring (512) is fixedly connected with a fixed disc (513), and the supporting ring (511) is used for supporting the embedded ring (512).

6. An adjustable drum brake for an electric vehicle as set forth in claim 5, wherein: the transmission part (52) comprises an end gear (521) fixedly connected to the outer surface of the fixed disc (513) and an outer gear ring (522) fixedly connected to one side of the end gear (521), the outer gear ring (522) is in meshed connection with the spur gear (422), a balancing weight (523) is fixedly connected to the lowest position inside the outer gear ring (522), and the balancing weight (523) is used for controlling the angle of the spur gear (422).

7. An adjustable drum brake for an electric vehicle as set forth in claim 6, wherein: the centrifugal rotating component (53) comprises a connecting ring (531) fixedly connected to the inner wall of the brake drum (1) and a rotating ring (532) fixedly connected to the other end of the connecting ring (531), a mounting hole (533) is formed in the inner side of the rotating ring (532), a pressure spring (534) is fixedly connected to the inner wall of the mounting hole (533), an embedded rod (535) is fixedly connected to the other end of the pressure spring (534), the embedded rod (535) is movably connected with the mounting hole (533) in an embedded mode, and four groups of the mounting hole (533), the pressure spring (534) and the embedded rod (535) are uniformly arranged in an annular mode, and the pressure spring (534) is used for extruding the embedded rod (535) to move.

8. An adjustable drum brake for electric vehicles according to claim 7, wherein: one end of the fixed disc (513) is fixedly connected with a transmission ring (514), an embedding hole (515) is formed in the outer surface of the transmission ring (514), four groups of embedding holes (515) are uniformly formed in an annular shape, the four groups of embedding rods (535) are respectively movably embedded with the four groups of embedding holes (515), and the embedding rods (535) are used for driving the transmission ring (514) to rotate.

9. An adjustable drum brake for an electric vehicle as set forth in claim 8, wherein: the blowing component (54) comprises a positioning plate (541) fixedly connected to the inner wall of the brake bottom plate (2) and a transmission shaft (542) rotatably connected to one side of the positioning plate (541), wherein a bevel gear (543) and a fan (544) are fixedly connected to the outer surface of the transmission shaft (542) at intervals, the bevel gear (543) is meshed with the face gear (521), and the face gear (521) is used for driving the fan (544) to rotate.

10. An adjustable drum brake for electric vehicles according to claim 3, wherein: the outer surface of the brake pad (73) is arranged to be a convex arc, the inner wall of the brake drum (1) is provided with a jogged groove (11), the jogged groove (11) is matched with the radian of the outer surface of the brake pad (73), and the jogged groove (11) is used for enlarging the contact area.