阅读说明：本技术 间隙自调鼓式制动器 (Drum brake with self-adjusting clearance ) 是由 徐宇 徐旗钊 乔冠朋 鞠银峰 吴玉初 吴恺 黄�俊 徐剑峰 张志江 陈林 于 2020-06-08 设计创作，主要内容包括：本发明涉及间隙自调鼓式制动器,包括制动底板,其前端面两侧对称布置制动蹄,位于两制动蹄上部间隙处的制动底板前端面延伸有腔室,腔室内安装凸轮轴；位于腔室内的凸轮轴端头安装凸轮,凸轮侧边配合安装间隙补偿机构,间隙补偿机构两端部伸出腔室且端头分别与对应的制动蹄上部卡装；位于腔室内部的间隙补偿机构上啮合安装间隙调整机构,间隙调整机构与凸轮轴卡装；外力驱动凸轮轴转动,其端部的凸轮经间隙补偿机构同时施加外张力于制动蹄,实现制动；制动间隙较大时,凸轮轴经间隙调整机构驱动间隙补偿机构轴向加长,从而减小制动间隙；本发明结构紧凑,布局合理,间隙补偿机构直接作用于制动蹄,稳定性好,并极大地便利于维护调整。(The invention relates to a clearance self-adjusting drum brake, which comprises a brake bottom plate, wherein brake shoes are symmetrically arranged on two sides of the front end surface of the brake bottom plate, a cavity extends from the front end surface of the brake bottom plate positioned at the clearance between the upper parts of the two brake shoes, and a cam shaft is arranged in the cavity; a cam is arranged at the end of the cam shaft positioned in the cavity, the side edge of the cam is matched with a clearance compensation mechanism, two end parts of the clearance compensation mechanism extend out of the cavity, and the end parts are respectively clamped with the upper parts of the corresponding brake shoes; a clearance adjusting mechanism is engaged and installed on the clearance compensation mechanism positioned in the cavity and is clamped with the camshaft; the cam at the end of the cam shaft applies external tension to the brake shoe through the clearance compensation mechanism to realize braking; when the braking clearance is larger, the camshaft drives the clearance compensation mechanism to axially lengthen through the clearance adjustment mechanism, so that the braking clearance is reduced; the invention has compact structure and reasonable layout, the clearance compensation mechanism directly acts on the brake shoe, the stability is good, and the maintenance and the adjustment are greatly facilitated.)

1. The utility model provides a clearance self-modulation drum brake, includes soleplate (1), and soleplate (1) preceding terminal surface bilateral symmetry has circular-arc brake shoe (2), its characterized in that: a chamber (102) extends from the front end surface of the brake bottom plate (1) positioned at the upper gap of the two brake shoes (2), and a cam shaft (7) is installed in the chamber (102); the cam shaft (7) extends into the cavity (102) from the rear end face of the brake bottom plate (1), a cam (71) is mounted at the end of the cam shaft (7) positioned in the cavity (102), a gap compensation mechanism (3) is mounted at the side edge of the cam (71) in a matched mode, the end parts of the two ends of the gap compensation mechanism (3) extend out of the cavity (102), and the two end parts of the gap compensation mechanism (3) positioned outside the cavity (102) are respectively clamped with the upper parts of the corresponding brake shoes (2); and a clearance adjusting mechanism (4) is engaged and installed on the clearance compensation mechanism (3) positioned in the cavity (102), and the clearance adjusting mechanism (4) is clamped with the camshaft (7).

2. A gap self-adjusting drum brake as claimed in claim 1, characterized in that: the upper parts of the two brake shoes (2) are interconnected through a large spring (10), and the lower parts of the two brake shoes (2) are interconnected through a small spring (11); shoe shafts (12) are symmetrically arranged on the brake bottom plate (1) positioned in the gap between the lower parts of the two brake shoes (2), and the lower end of each brake shoe (2) is clamped with the corresponding shoe shaft (12).

3. A gap self-adjusting drum brake as claimed in claim 1, characterized in that: a dust cover (6) is fixedly arranged on the rear end face of the brake bottom plate (1), and brake shoes (2) on two sides are contained by turned-over edges on the edge of the dust cover (6); an air chamber bracket (5) penetrates through the dust cover (6) from back to front, and the front end surface of the air chamber bracket (5) is fixedly installed with the brake bottom plate (1); the camshaft (7) penetrates through the air chamber support (5) from front to back, and an adjusting arm (8) is arranged on the camshaft (7) positioned outside the rear end of the air chamber support (5); and a plurality of friction plates (9) are arranged on the outer arc surface of each brake shoe (2).

4. A gap self-adjusting drum brake as claimed in claim 1, characterized in that: the structure of the clearance adjusting mechanism (4) is as follows: the transmission mechanism comprises an upper tooth holder (402) and a lower tooth holder (401) which are vertically matched and fixedly arranged, a rotating shaft (411) is sequentially arranged from top to bottom through the upper tooth holder (402) and the lower tooth holder (401), and a transmission wheel (403) is sleeved on the rotating shaft (411) positioned above the upper tooth holder (402); a regulating sleeve (405) is sleeved on the rotating shaft (411) above the transmission wheel (403) in a clearance mode, a regulating sleeve (407) is mounted on the inner wall surface of the regulating sleeve (405) through a one-way bearing (414), the regulating sleeve (407) is sleeved on the rotating shaft (411), the upper portion of the regulating sleeve (407) penetrates upwards through the regulating sleeve (405), and a cover cap (409) is clamped on the rotating shaft (411) above the regulating sleeve (407); a tooth sheet set (408) is arranged between the cover cap (409) and the adjusting sleeve (407); the circumferential wall surfaces of the upper tooth holder (402) and the lower tooth holder (401) are jointly provided with a support shaft (412), the ends of the support shaft (412) positioned in the upper tooth holder (402) and the lower tooth holder (401) are provided with a driven wheel (410), and the driven wheel (410) is meshed with the bevel teeth of the transmission wheel (403); the outer wall surface of the adjusting sleeve (405) is clamped with the camshaft (7), the bevel gear of the driven wheel (410) penetrates out of the bottom surface of the lower tooth holder (401) downwards, and the driven wheel (410) positioned at the bottom of the lower tooth holder (401) is meshed with the clearance compensation mechanism (3).

5. A gap self-adjusting drum brake as claimed in claim 4, characterized in that: a spring (406) is arranged between the shifting sleeve (405) and the tooth sheet set (408), the tooth sheet set (408) comprises outer tooth sheets (4081) and inner tooth sheets (4082) which are stacked at intervals, and the adjacent inner tooth sheets (4082) and outer tooth sheets (4081) are in friction transmission; the inner tooth plate (4082) is clamped with an inner tooth groove (4071) of the adjusting sleeve (407) through inner teeth, and the outer tooth plate (4081) is clamped with an outer tooth groove (4091) of the cover cap (409) through outer teeth; two end parts of a rotating shaft (411) positioned above the cover cap (409) and below the lower tooth holder (401) are respectively clamped with a retaining ring (413); the top end of the rotating shaft (411) extends backwards out of the brake bottom plate (1).

6. A gap self-adjusting drum brake as claimed in claim 4, characterized in that: the circumferential wall surface of the adjusting and stirring sleeve (405) is provided with an adjusting and stirring hole (4051), the circumferential wall of the camshaft (7) is provided with a pin hole (72), a pin shaft is fixedly arranged in the pin hole (72), and the end part of the pin shaft extends into the adjusting and stirring hole (4051); the size of the shifting hole (4051) along the circumferential direction of the shifting sleeve (405) is larger than that of the pin shaft.

7. A gap self-adjusting drum brake as claimed in claim 4, characterized in that: a gasket (404) is arranged between the bottom surface of the adjusting sleeve (405) and the top surface of the upper tooth holder (402); the gasket (404) comprises a laminated flat gasket and butterfly gasket.

8. A gap self-adjusting drum brake as claimed in claim 1, characterized in that: the clearance compensation mechanism (3) has the structure that: the device comprises a limiting plate (31) fixedly mounted with the front end of a chamber (102), a rotating shaft (33) is rotatably mounted on the inner side surface of the limiting plate (31), the axial direction of the rotating shaft (33) is vertical to the axial direction of a cam shaft (7), and two ends of the rotating shaft (33) are respectively sleeved with a synchronizing wheel (34); the single synchronizing wheel (34) is engaged with and assembled with piston cylinders (36), and the two piston cylinders (36) are arranged at intervals and have the axial directions positioned on the same straight line; the end parts of the opposite ends of the two piston cylinders (36) are respectively clamped with piston heads (37) through clamp springs, and the end parts of the opposite back ends of the two piston cylinders (36) are respectively provided with a screw rod (35) in a threaded fit manner; the opposite surfaces of the two piston heads (37) are in contact with the cam (71) together, the outer end heads of the two screw rods (35) extend to the outside of the cavity (102) respectively, and the outer end heads of the two screw rods (35) are clamped with the corresponding brake shoes (2).

9. A gap self-adjusting drum brake as claimed in claim 8, characterized in that: the inner side surface of the limiting plate (31) extends inwards to form lugs (32) which are arranged in parallel, through holes are formed in the two lugs (32) in a penetrating mode, the rotating shaft (33) penetrates through the two lugs (32) through the through holes, and two ends of the rotating shaft (33) located outside the two lugs (32) are respectively sleeved with a synchronizing wheel (34); the inner ends of the single lugs (32) are respectively extended with a protrusion (321), the circumferential surface of the piston head (37) positioned outside the piston cylinder (36) is provided with a groove (371) along the axial direction, and the protrusions (321) are accommodated in the grooves (371); the inner side surfaces of the piston head (37) which face each other extend inwards along the axial direction to form a convex block (372), and the groove (371) is positioned on the convex block (372).

10. A gap self-adjusting drum brake as claimed in claim 1, characterized in that: the brake bottom plate (1) is structurally characterized in that: the plate comprises a plate body (101), wherein a chamber (102) extends forwards from the upper end of the front side surface of the plate body (101), a main through hole (104) is formed in the front and rear through chambers (102), transverse holes (105) are formed in the left and right through chambers (102), a side hole (103) communicated with the transverse hole (105) is further formed in the chamber (102) positioned on the side edge of the main through hole (104), and the axial direction of the side hole (103) is parallel to the main through hole (104); the lower end part of the front side surface of the plate body (101) extends forwards to form a boss (106), and shaft holes (107) are formed in parallel in a manner of penetrating the boss (106) from front to back.

Technical Field

The invention relates to the technical field of drum brakes, in particular to a clearance self-adjusting drum brake.

Background

The market of commercial vehicles is subject to rapid changes under the influence of relevant regulations and policies, and the wheel end brakes in the braking systems mainly comprise drum brakes and disc brakes, which have been increasing year by year with their own dominance, but the drum brakes still dominate the market. According to the regulation requirement, the brake is provided with a wear compensation device, and the wear of a friction pair can be automatically compensated so as to ensure the stability of a brake clearance; the clearance self-regulating mechanism of the pneumatic drum brake mainly comprises a regulating arm self-regulating mechanism and a wedge type self-regulating mechanism.

The adjusting position of the adjusting arm self-adjusting mechanism is arranged at the outer side of the brake, the cam shaft respectively acts on the leading brake shoe and the trailing brake shoe, the clearance adjusting effect of the cam shaft is greatly influenced by the rigid deformation of the cam shaft and the symmetric synchronous transmission of the cam, and the requirements on the rigidity and the symmetry precision of the cam shaft are high; the clearance adjusting mode is easy to cause unstable clearance or deviation risk.

Although the wedge brake clearance adjusting mechanism is arranged at the shoe end, the clearance adjusting position moves along with the rotation of the brake shoe, the mechanism is complicated in adjusting operation, the clearance adjusting is inconvenient, and subsequent market replacement and maintenance are inconvenient.

Disclosure of Invention

The applicant provides a clearance self-adjusting drum brake with a reasonable structure aiming at the defects in the prior art, so that a clearance self-adjusting compensation mechanism is arranged in the brake and directly acts on a shoe end, the stability is high, and the maintenance and the adjustment of the subsequent market are greatly facilitated.

The technical scheme adopted by the invention is as follows:

a drum brake with self-adjusting clearance comprises a brake bottom plate, wherein arc-shaped brake shoes are symmetrically arranged on two sides of the front end surface of the brake bottom plate, a cavity extends from the front end surface of the brake bottom plate at the clearance between the upper parts of the two brake shoes, and a cam shaft is arranged in the cavity; the cam shaft extends into the cavity from the rear end face of the brake bottom plate, a cam is mounted at the end of the cam shaft positioned in the cavity, a clearance compensation mechanism is mounted at the side edge of the cam in a matched mode, the end parts of the two ends of the clearance compensation mechanism extend out of the cavity, and the two end parts of the clearance compensation mechanism positioned outside the cavity are respectively clamped with the upper parts of the corresponding brake shoes; and a clearance adjusting mechanism is engaged and installed on the clearance compensation mechanism positioned in the cavity and is clamped with the camshaft.

As a further improvement of the above technical solution:

the upper parts of the two brake shoes are interconnected through a large spring, and the lower parts of the two brake shoes are interconnected through a small spring; shoe shafts are symmetrically arranged on the brake bottom plate positioned in the gap between the lower parts of the two brake shoes, and the lower end heads of the single brake shoes are clamped with the corresponding shoe shafts.

A dust cover is fixedly arranged on the rear end face of the brake bottom plate, and brake shoes on two sides are contained by turned-over edges on the edge of the dust cover; an air chamber bracket penetrates through the dust cover from back to front and is fixedly installed on the front end surface of the air chamber bracket and the brake bottom plate; the camshaft penetrates through the air chamber support from front to back, and an adjusting arm is arranged on the camshaft positioned outside the rear end of the air chamber support; and a plurality of friction plates are arranged on the outer arc surface of each brake shoe.

The structure of the clearance adjusting mechanism is as follows: the transmission mechanism comprises an upper tooth holder and a lower tooth holder which are fixedly matched up and down, a rotating shaft is sequentially arranged through the upper tooth holder and the lower tooth holder from top to bottom, and a driving wheel is sleeved on the rotating shaft above the upper tooth holder; the adjusting sleeve is sleeved on the rotating shaft above the driving wheel in a clearance mode, the inner wall surface of the adjusting sleeve is provided with the adjusting sleeve through a one-way bearing, the adjusting sleeve is sleeved on the rotating shaft, the upper portion of the adjusting sleeve upwards penetrates through the adjusting sleeve, and the rotating shaft above the adjusting sleeve is clamped with the cap; a tooth sheet group is arranged between the cap and the adjusting sleeve; the circumferential wall surfaces of the upper tooth holder and the lower tooth holder are jointly provided with a support shaft, the end heads of the support shafts positioned in the upper tooth holder and the lower tooth holder are provided with driven wheels, and the driven wheels are meshed with bevel teeth of the driving wheels; the outer wall surface of the adjusting sleeve is clamped with the camshaft, the bevel gear of the driven wheel downwards penetrates out of the bottom surface of the lower tooth holder, and the driven wheel positioned at the bottom of the lower tooth holder is meshed with the clearance compensation mechanism.

A spring is arranged between the adjusting sleeve and the tooth plate group, the tooth plate group comprises outer tooth plates and inner tooth plates which are stacked at intervals, and the adjacent inner tooth plates and the outer tooth plates are in friction transmission; the inner tooth plate is clamped with the inner tooth socket of the adjusting sleeve through inner teeth, and the outer tooth plate is clamped with the outer tooth socket of the cap through outer teeth; two end parts of the rotating shaft, which are positioned above the cap and below the lower tooth holder, are respectively clamped with a retaining ring; the top end of the rotating shaft extends backwards out of the brake bottom plate.

The circumferential wall surface of the adjusting and stirring sleeve is provided with an adjusting and stirring hole, the circumferential wall of the camshaft is provided with a pin hole, a pin shaft is fixedly arranged in the pin hole, and the end part of the pin shaft extends into the adjusting and stirring hole; the size of the adjusting hole along the circumferential direction of the adjusting sleeve is larger than that of the pin shaft.

A gasket is arranged between the bottom surface of the shifting sleeve and the top surface of the upper tooth seat; the gasket includes a flat gasket and a butterfly gasket that are stacked.

The structure of the clearance compensation mechanism is as follows: the device comprises a limiting plate fixedly mounted at the front end of a cavity, a rotating shaft is rotatably mounted on the inner side surface of the limiting plate, the axial direction of the rotating shaft is vertical to the axial direction of a cam shaft, and synchronizing wheels are respectively sleeved at two end parts of the rotating shaft; the single synchronizing wheel is provided with piston cylinders in a meshing way, and the two piston cylinders are arranged at intervals and have the axial directions positioned on the same straight line; the end parts of the opposite ends of the two piston cylinders are respectively clamped with piston heads through snap springs, and the end parts of the opposite back ends of the two piston cylinders are respectively provided with a screw rod in a threaded fit manner; the opposite surfaces of the two piston heads are in contact with the cam together, the outer end heads of the two screw rods extend to the outside of the cavity respectively, and the outer end heads of the two screw rods are clamped with the corresponding brake shoes.

The inner side surface of the limiting plate extends inwards to form lugs arranged in parallel, through holes are formed in the lugs in a penetrating mode, the rotating shaft penetrates through the lugs through the through holes, and two ends of the rotating shaft, located outside the lugs, are respectively sleeved with a synchronizing wheel; the inner ends of the single lugs are extended with protrusions, the circumferential surface of the piston head positioned outside the piston cylinder is provided with a groove along the axial direction, and the protrusions are accommodated in the grooves; the piston head has a protrusion extending axially inward from the inner facing surface of the piston head, and the recess is located on the protrusion.

The structure of the brake bottom plate is as follows: the plate comprises a plate body, wherein a cavity extends forwards from the upper end of the front side surface of the plate body, a main through hole is formed in the front and rear penetrating cavities, transverse holes are formed in the left and right penetrating cavities, a side hole penetrating through the transverse holes is further formed in the cavity positioned on the side edge of the main through hole, and the axial direction of the side hole is parallel to the main through hole; the lower end part of the front side surface of the plate body extends forwards to form a boss, and the front and the rear through bosses are provided with shaft holes in parallel.

The invention has the following beneficial effects:

the invention has compact and reasonable structure and convenient operation, drives the cam shaft to rotate through the adjusting arm, and simultaneously applies external tension to the brake shoe through the cam at the end part of the cam shaft by the clearance compensation mechanism to realize braking; when the brake clearance is larger, a pin shaft in a pin hole on the side wall surface of the camshaft applies circumferential rotating force to the clearance adjusting mechanism, the clearance adjusting mechanism works, and the driven wheel drives the clearance compensating mechanism meshed with the clearance adjusting mechanism to work, so that the clearance compensating mechanism is axially lengthened, the brake clearance on the outer side surfaces of the brake shoes on two sides is reduced, the self-adjustment of the brake clearance is realized, the stability is good, and the reliability is good; the clearance compensation mechanism directly acts on the end of the brake shoe and synchronously applies force to the leading shoe and the trailing shoe, so that the synchronization of the leading shoe and the trailing shoe is effectively ensured; the rotating shaft of the clearance adjusting mechanism extends backwards out of the brake bottom plate, so that the subsequent market can adjust the brake clearance through the rotating shaft, and the operation is convenient;

the invention also comprises the following advantages:

the pin shaft in the pin hole on the side wall surface of the camshaft applies circumferential external force to the adjusting sleeve in the clearance adjusting mechanism, the adjusting sleeve rotates, the rotating shaft and the driving wheel are driven to rotate through the one-way bearing, the adjusting sleeve, the gear set and the cap, the driven wheel rotates along with the rotating shaft and then shifts one piston cylinder of the clearance compensating mechanism to rotate, a screw rod in threaded connection with the piston cylinder is axially screwed out due to circumferential limit of the corresponding brake shoe, synchronously, the piston cylinder drives another piston cylinder to synchronously rotate through the meshed synchronizing wheel, the rotating shaft and the other synchronizing wheel, so that the other screw rod is synchronously screwed out, thereby realizing synchronous compensation of brake clearances of the brake shoes on two sides, and having good consistency;

the clearance adjusting mechanism and the clearance compensation mechanism are uniformly distributed in a cavity on the upper part of the brake bottom plate, the structure is compact, the layout is reasonable, and the assistance force is directly acted on the brake shoe end by the clearance compensation mechanism;

the cam of the cam shaft reciprocates within a preset rotation range, and the existence of a one-way bearing between the adjusting sleeve and the adjusting sleeve in the clearance adjusting mechanism assists the realization of one-way compensation, so that the reciprocating stroke of the cam is not required to be expanded due to the clearance compensation, and the braking stability is effectively ensured; the clearance adjusting mechanism compensates and adjusts the brake clearance in time, the stability of the brake clearance is guaranteed, and the overload protection and the anti-damping of the clearance adjusting mechanism further guarantee the working stability of the drum brake.

Drawings

FIG. 1 is a schematic structural diagram of the present invention.

Fig. 2 is an exploded view of fig. 1.

FIG. 3 is a schematic view of the installation of the camshaft with the clearance compensation mechanism and the clearance adjustment mechanism according to the present invention.

Fig. 4 is a partially enlarged view of a portion a in fig. 3.

Fig. 5 is a schematic structural diagram of the gap adjustment mechanism of the present invention.

Fig. 6 is an exploded view (spring omitted) of the gap adjustment mechanism of the present invention.

Fig. 7 is a partially enlarged view of a portion B in fig. 6.

FIG. 8 is a schematic view of the assembly of the adjusting sleeve, the set of teeth and the cap according to the present invention.

Fig. 9 is a schematic structural view of the backlash compensation mechanism of the present invention.

Fig. 10 is an exploded view of the gap compensation mechanism of the present invention.

Fig. 11 is a schematic view of the retainer plate and piston head assembly of the present invention.

Fig. 12 is a schematic structural view of the brake backing plate of the present invention.

Wherein: 1. braking the bottom plate; 2. a brake shoe; 3. a clearance compensation mechanism; 4. a gap adjusting mechanism; 5. an air chamber support; 6. a dust cover; 7. a camshaft; 8. an adjusting arm; 9. a friction plate; 10. a large spring; 11. a small spring; 12. a hoof sheet axis;

101. a plate body; 102. a chamber; 103. a side hole; 104. a main through hole; 105. a transverse bore; 106. a boss; 107. a shaft hole;

31. a limiting plate; 32. a lug; 33. a rotating shaft; 34. a synchronizing wheel; 35. a screw; 36. a piston cylinder; 37. a piston head; 321. a protrusion; 371. a groove; 372. a bump;

401. a lower tooth holder; 402. an upper tooth holder; 403. a driving wheel; 404. a gasket; 405. adjusting a sleeve; 406. a spring; 407. an adjusting sleeve; 408. a tooth sheet group; 409. capping; 410. a driven wheel; 411. a rotating shaft; 412. a support shaft; 413. a retainer ring; 414. a one-way bearing; 4051. adjusting and poking holes; 4071. an inner tooth socket; 4081. an outer blade; 4082. an inner tooth sheet; 4091. an outer gullet;

71. a cam; 72. a pin hole.

Detailed Description

The following describes embodiments of the present invention with reference to the drawings.

As shown in fig. 1, 2 and 3, the self-adjusting clearance drum brake of the present embodiment includes a brake base plate 1, arc-shaped brake shoes 2 are symmetrically arranged on both sides of a front end surface of the brake base plate 1, a cavity 102 extends from the front end surface of the brake base plate 1 at a clearance between upper portions of the two brake shoes 2, and a cam shaft 7 is installed in the cavity 102; the camshaft 7 extends into the chamber 102 from the rear end surface of the brake bottom plate 1, the end of the camshaft 7 positioned in the chamber 102 is provided with a cam 71, the side edge of the cam 71 is provided with a clearance compensation mechanism 3 in a matching way, the end parts of the two ends of the clearance compensation mechanism 3 extend out of the chamber 102, and the two end parts of the clearance compensation mechanism 3 positioned outside the chamber 102 are respectively clamped with the upper parts of the corresponding brake shoes 2; the clearance compensation mechanism 3 positioned in the chamber 102 is engaged with the clearance adjusting mechanism 4, and the clearance adjusting mechanism 4 is clamped with the camshaft 7.

The cam shaft 7 rotates, and the cam 71 at the end part of the cam shaft simultaneously applies external tension to the brake shoe 2 through the clearance compensation mechanism 3 to realize braking; when the braking gap is large, a pin shaft in a pin hole 72 on the side wall surface of the camshaft 7 applies circumferential rotating force to the gap adjusting mechanism 4, the gap adjusting mechanism 4 works, and the driven wheel 410 drives the gap compensating mechanism 3 meshed with the gap adjusting mechanism to work, so that the gap compensating mechanism 3 is axially lengthened, the braking gap on the outer side surfaces of the brake shoes 2 on two sides is reduced, and the self-regulation of the braking gap is realized; the clearance compensation mechanism 3 directly acts on the end of the brake shoe 2 and synchronously applies force to the leading shoe and the trailing shoe, so that the synchronization of the leading shoe and the trailing shoe is effectively ensured; the clearance adjusting mechanism 4 and the clearance compensation mechanism 3 are uniformly distributed in the cavity 102 at the upper part of the brake bottom plate 1, the structure is compact, the layout is reasonable, and the assistance force directly acts on the end of the brake shoe 2 through the clearance compensation mechanism 3.

The upper parts of the two brake shoes 2 are interconnected through a large spring 10, and the lower parts of the two brake shoes 2 are interconnected through a small spring 11; shoe shafts 12 are symmetrically arranged on the brake bottom plate 1 positioned in the gap between the lower parts of the two brake shoes 2, and the lower end of each brake shoe 2 is clamped with the corresponding shoe shaft 12; the concave ring structure at the lower end of the brake shoe 2 is clamped with the circumference of a shoe plate shaft 12 and matched with a large spring 10 and a small spring 11 for return, so that the brake shoe 2 is installed in a floating mode relative to the brake bottom plate 1, and the return spring structures are symmetrically distributed relative to the brake center and assist the overall stability of the brake mechanism.

A dust cover 6 is fixedly arranged on the rear end face of the brake bottom plate 1, and brake shoes 2 on two sides are contained by turned-over edges on the edge of the dust cover 6; an air chamber bracket 5 penetrates through the dust cover 6 from back to front, and the front end face of the air chamber bracket 5 is fixedly installed with the brake bottom plate 1; the camshaft 7 penetrates through the air chamber bracket 5 from front to back, and an adjusting arm 8 is arranged on the camshaft 7 positioned outside the rear end head of the air chamber bracket 5; a plurality of friction plates 9 are arranged on the outer arc surface of each brake shoe 2.

As shown in fig. 5 and 6, the gap adjustment mechanism 4 has a structure in which: the gear transmission mechanism comprises an upper gear seat 402 and a lower gear seat 401 which are vertically matched and fixedly arranged, a rotating shaft 411 is sequentially arranged from top to bottom through the upper gear seat 402 and the lower gear seat 401, and a driving wheel 403 is sleeved on the rotating shaft 411 above the upper gear seat 402; an adjusting sleeve 405 is sleeved on the rotating shaft 411 above the driving wheel 403 in a clearance mode, an adjusting sleeve 407 is mounted on the inner wall surface of the adjusting sleeve 405 through a one-way bearing 414, the adjusting sleeve 407 is sleeved on the rotating shaft 411, the upper portion of the adjusting sleeve 407 upwards penetrates through the adjusting sleeve 405, and a cover cap 409 is clamped on the rotating shaft 411 above the adjusting sleeve 407; a tooth sheet group 408 is arranged between the cover cap 409 and the adjusting sleeve 407; a supporting shaft 412 is arranged on the circumferential wall surfaces of the upper tooth holder 402 and the lower tooth holder 401, a driven wheel 410 is arranged at the end of the supporting shaft 412 positioned in the upper tooth holder 402 and the lower tooth holder 401, and the driven wheel 410 is engaged and assembled with the bevel gear of the driving wheel 403; the outer wall surface of the adjusting sleeve 405 is clamped with the camshaft 7, the bevel gear of the driven wheel 410 downwards penetrates out of the bottom surface of the lower tooth holder 401, and the driven wheel 410 positioned at the bottom of the lower tooth holder 401 is meshed with the clearance compensation mechanism 3.

A spring 406 is arranged between the adjusting sleeve 405 and the tooth plate group 408, as shown in fig. 8, the tooth plate group 408 comprises an outer tooth plate 4081 and an inner tooth plate 4082 which are stacked at intervals, and friction transmission is performed between the adjacent inner tooth plates 4082 and the adjacent outer tooth plates 4081; the compression force of the spring 406 ensures the friction transmission between the inner tooth plate 4082 and the outer tooth plate 4081 in the tooth plate group 408, and the assistance is realized on the overload protection function in the mechanism; the inner tooth piece 4082 is clamped with the inner tooth groove 4071 of the adjusting sleeve 407 through inner teeth, and the outer tooth piece 4081 is clamped with the outer tooth groove 4091 of the cover cap 409 through outer teeth; two end parts of the rotating shaft 411 positioned above the cover cap 409 and below the lower tooth holder 401 are respectively clamped with a retaining ring 413; the top end of the rotating shaft 411 extends backwards out of the brake base plate 1.

As shown in fig. 7, the circumferential wall surface of the adjusting sleeve 405 is provided with an adjusting hole 4051, the circumferential wall of the camshaft 7 is provided with a pin hole 72, as shown in fig. 4, a pin shaft is fixedly installed in the pin hole 72, and the end of the pin shaft extends into the adjusting hole 4051; the size of the dialing hole 4051 along the circumferential direction of the dialing sleeve 405 is larger than that of the pin shaft.

A pin shaft in a pin hole 72 on the side wall surface of the camshaft 7 applies a circumferential external force to the adjusting and shifting sleeve 405 in the clearance adjusting mechanism 4 through the adjusting and shifting hole 4051; the cam 71 of the camshaft 7 reciprocates within a preset rotation range, and the existence of the one-way bearing 414 between the adjusting sleeve 405 and the adjusting sleeve 407 in the clearance adjusting mechanism 4 helps to realize one-way compensation, so that the reciprocating stroke of the cam 71 is not required to be enlarged due to clearance compensation, and the braking stability is effectively ensured.

A gasket 404 is arranged between the bottom surface of the adjusting sleeve 405 and the top surface of the upper tooth holder 402; the gasket 404 comprises a flat gasket and a butterfly gasket which are overlapped, and the existence of the butterfly gasket effectively buffers the shaking of the adjusting sleeve 405 under the external vibration, so that the transmission of the circumferential force between the adjusting sleeve 405 and the camshaft 7 is ensured.

As shown in fig. 9 and 10, the backlash compensation mechanism 3 has a structure in which: the device comprises a limiting plate 31 fixedly mounted at the front end of a chamber 102, a rotating shaft 33 is rotatably mounted on the inner side surface of the limiting plate 31, the axial direction of the rotating shaft 33 is vertical to the axial direction of a camshaft 7, and two ends of the rotating shaft 33 are respectively sleeved with a synchronizing wheel 34; the single synchronizing wheel 34 is respectively provided with piston cylinders 36 in a meshing way, and the two piston cylinders 36 are arranged at intervals and have the axial directions positioned on the same straight line; the end parts of the opposite ends of the two piston cylinders 36 are respectively clamped with a piston head 37 through clamp springs, the clamp springs enable the piston head 37 and the piston cylinder 36 to axially move synchronously, but the piston cylinders 36 can rotate relative to the piston head 37 under the action of stress; the ends of the opposite back ends of the two piston cylinders 36 are respectively provided with a screw 35 in a threaded manner; the opposite surfaces of the two piston heads 37 are in contact with the cam 71 together, the outer end heads of the two screw rods 35 extend to the outside of the chamber 102 respectively, the outer end heads of the two screw rods 35 are clamped with the corresponding brake shoes 2, and the circumferential rotation of the screw rods 35 is limited by the brake shoes 2; the outer wall surface of one of the piston cylinders 36 is fitted in mesh with the driven pulley 410 in the gap adjusting mechanism 4.

The inner side surface of the limit plate 31 extends inwards to form lugs 32 which are arranged in parallel, through holes are formed by penetrating through the two lugs 32, a rotating shaft 33 penetrates through the two lugs 32 through the through holes, and two ends of the rotating shaft 33 positioned outside the two lugs 32 are respectively sleeved with a synchronizing wheel 34; as shown in fig. 11, the inner ends of the individual lugs 32 are extended with protrusions 321, the circumferential surface of the piston head 37 outside the piston cylinder 36 is provided with grooves 371 along the axial direction, and the protrusions 321 are accommodated in the grooves 371; the opposite inner side of piston head 37 extends axially inward with a projection 372, and a groove 371 is located on projection 372; when piston head 37 is driven by cam 71 to move axially in the direction of piston cylinder 36, protrusion 321 moves axially in the opposite direction relative to groove 371 on piston head 37, and the cooperation of protrusion 321 and groove 371 acts as a limit to the axial movement of piston head 37.

As shown in fig. 12, the brake backing plate 1 has a structure in which: the brake shoe comprises a plate body 101, wherein a chamber 102 extends forwards at the upper end of the front side surface of the plate body 101, a main through hole 104 is formed in the front and rear through chambers 102, a cam shaft 7 is accommodated in the main through hole 104, transverse holes 105 are formed in the left and right through chambers 102, a clearance compensation mechanism 3 is accommodated in the transverse holes 105, a side hole 103 communicated with the transverse hole 105 is further formed in the chamber 102 positioned on the side edge of the main through hole 104, the axial direction of the side hole 103 is parallel to the main through hole 104, a clearance adjustment mechanism 4 is accommodated in the side hole 103, and the end of a rotating shaft 411 in the clearance adjustment mechanism 4 extends out of a brake shoe 1 through a rear; a boss 106 extends forward from the lower end of the front side of the plate body 101, a shaft hole 107 is formed in parallel in the front and rear direction through the boss 106, and the shoe shaft 12 is mounted in the shaft hole 107.

The working principle of the invention is as follows:

the adjusting arm 8 drives the camshaft 7 to rotate, the cam 71 at the end of the camshaft 7 applies force to the axial movement force of the two piston heads 37 at the same time, the piston cylinder 36 and the screw rod 35 move outwards along with the axial movement of the piston heads 37, so that the outer end heads of the two screw rods 35 move outwards and synchronously push the corresponding brake shoes 2 to expand outwards, namely the leading shoes and the trailing shoes move outwards synchronously to brake, and the synchronous axial movement of the coaxial screw rods 35 is realized;

when the brake clearance is large, when the camshaft 7 rotates, the pin shaft in the pin hole 72 on the side wall surface applies force to the adjusting and shifting sleeve 405 in the clearance adjusting mechanism 4 through the adjusting and shifting hole 4051; the adjusting sleeve 405 rotates, the adjusting sleeve 407 is driven to rotate through the one-way bearing 414, the adjusting sleeve 407 drives the tooth sheet set 408 to synchronously rotate in cooperation with the compression pressure of the spring 406 acting on the tooth sheet set 408, the tooth sheet set 408 drives the cap 409 to rotate, the cap 409 drives the rotating shaft 411 to rotate, so that the driving wheel 403 rotates along with the rotating shaft 411, the driven wheel 410 meshed with the bevel gear of the driving wheel 403 rotates, and the bevel gear of the driven wheel 410 downwards extending out of the bottom surface of the lower tooth holder 401 drives the clearance compensation mechanism 3 to work; the clearance adjusting mechanism 4 unidirectionally converts the circumferential force axially parallel to the adjusting sleeve 405 into circumferential transmission of the driven wheel 410 axially perpendicular to the adjusting sleeve 405;

the driven wheel 410 rotates to enable the piston cylinder 36 meshed with the driven wheel to rotate around the axial direction of the driven wheel, the screw rod 35 in threaded connection with the piston cylinder 36 is limited corresponding to the circumferential direction of the brake shoe 2, and the screw rod 35 is axially screwed out relative to the piston cylinder 36; synchronously, the piston cylinder 36 drives the engaged synchronous wheel 34 to rotate, the fixed rotating shaft 33 and the other synchronous wheel 34 rotate along with the rotating shaft, so that the other piston cylinder 36 is driven to synchronously rotate, the other screw rod 35 is synchronously screwed out, the brake shoes 2 at two sides, namely the leading shoe and the trailing shoe, are driven to synchronously move outwards relative to the piston cylinder 36, and the synchronous adjustment of the brake clearance at the outer side of the brake shoe 2 is realized.

When the circumferential external force transmitted to the dial sleeve 405 by the camshaft 7 exceeds a certain value and is transmitted to the tooth piece set 408 through the one-way bearing 414 and the adjusting sleeve 407, sliding friction is generated between the inner tooth piece 4082 and the outer tooth piece 4081 in the tooth piece set 408, so that the tooth piece set 408 does not rotate synchronously with the adjusting sleeve 407, that is, the adjusting sleeve 407 cannot drive the cap 409 to rotate through the tooth piece set 408, and the overload protection effect is achieved.

When the camshaft 7 rotates reversely, the circumferential force applied to the adjusting and dialing sleeve 405 by the camshaft is reversed, the adjusting and dialing sleeve 405 rotates reversely, and the adjusting and dialing sleeve 405 and the adjusting sleeve 407 are transmitted through the one-way bearing 414, so that the adjusting sleeve 407 does not rotate along with the adjusting and dialing sleeve 405 due to the existence of the one-way bearing 414, and the one-way self-adjustment of the gap is ensured.

Force is applied to the top of the rotating shaft 411 from the rear end face of the brake bottom plate 1, so that the rotating shaft 411 rotates and is transmitted to the clearance compensation mechanism 3 through the transmission wheel 403 and the driven wheel 410, and therefore the adjustment of the positive or negative braking clearance of the clearance compensation mechanism 3 is achieved, and the maintenance or replacement operation of the rear market is greatly facilitated.

The invention has compact structure and skillful and reasonable layout, realizes the self-regulation of the brake clearance of the brake shoe end of the drum brake, is stable and reliable, and is convenient to adjust and maintain in the rear market.

The above description is intended to be illustrative and not restrictive, and the scope of the invention is defined by the appended claims, which may be modified in any manner within the scope of the invention.