Drum brakes

Abstract

The present disclosure relates to a drum brake including a brake arm, a brake shoe, a base, and a braking torque detection device, wherein the brake shoe is hingedly connected to the brake arm via a brake shoe shaft, the brake arm has a long circular shaft hole through which the brake shoe shaft passes, a wear bar is installed on one wall of the long circular shaft hole to compress the brake shoe shaft during braking, the braking torque detection device includes a sensing plate and a tensile pressure sensor installed on the sensing plate, one end of the sensing plate is connected to the brake shoe shaft and the other end of the sensing plate is connected to the brake arm. The present disclosure relates to a drum brake including a brake arm, a brake shoe, a base, and a braking torque detection device, wherein the wear bar applies normal pressure to the brake shoe shaft, so that braking displacement of the brake shoe shaft in the long circular shaft hole does not create an indentation groove in the wear bar, thereby eliminating the adverse effect of the indentation groove on braking displacement of the brake shoe shaft and reducing braking torque detection deviation accordingly.

Description

[Technical field]

[0001] The present invention relates to electromagnetic brakes, and more particularly to drum-type brakes. [Background technology]

[0002] A conventional braking torque detection device installed in a brake adds a pressure sensor that detects the operating pressure of the brake spring in a spring box where the brake spring is installed, multiplies the detected pressure value by the friction coefficient between the brake drum and the brake disc to obtain the magnitude of the friction force that the brake drum applies to the brake disc, and calculates the braking torque of the brake in relation to the radius of the brake disc. The braking torque is calculated using a fixed friction coefficient, but the friction coefficient between the brake drum and the brake disc changes when the brake disc becomes wet with oil or water or overheats due to friction, and such changes cannot be accurately reflected by the braking torque detection device, so the detection results of the conventional braking torque detection device may not match the facts in certain situations.

[0003] The applicant's prior patent, Patent Document 1 "Hub Brake Torque True Value Detection Sensor", provided a viable technology for detecting brake braking torque. However, this technology has the drawback that the brake arm cannot be hardened due to the high toughness requirement, so the hardness cannot be effectively increased, and when the brake shoe shaft is repeatedly subjected to force due to frequent braking, an indentation groove appears on the hole wall of the long circular shaft hole through which the brake shoe shaft penetrates in the brake arm, and when the indentation groove is formed, the minute movement of the brake shoe shaft along the longitudinal direction of the brake arm is suppressed, and the detection data based on the tangential braking displacement of the brake shoe based on this minute movement is greatly distorted, and the detection data of the braking torque is greatly deviated. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] China Utility Model No. 208103623 Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a drum brake that solves the problem in the conventional braking torque detection device that the appearance of impression grooves on the wall of the shaft hole of the brake arm leads to distortion of detection data. [Means for solving the problem]

[0006] One possible embodiment of the present invention is a drum-type brake comprising a brake arm, a brake shoe, a base and a braking torque detection device, wherein the brake shoe is hingedly connected to the brake arm via a brake shoe shaft, the brake arm has a long circular shaft hole through which the brake shoe shaft passes, and a wear-resistant bar is installed on one side wall of the long circular shaft hole to press against the brake shoe shaft when the brake is applied, and the braking torque detection device comprises a sensing plate and a tensile pressure sensor installed on the sensing plate, one end of the sensing plate is connected to the brake shoe shaft and the other end of the sensing plate is connected to the brake arm.

[0007] The sensing plate is installed vertically, has one end having a hole and connected to the brake arm via a connecting shaft, and has the other end having a closed hole or an open groove, the brake shoe shaft passes through the closed hole or the open groove, and the axis of the brake shoe shaft is located at the longitudinal center of the long circular shaft hole in a static state.

[0008] A shaft sleeve is provided around the brake shoe shaft, and the shaft sleeve abuts against the wear bar.

[0009] When the brake shoe of the drum brake clamps the brake drum of the device to brake, frictional braking is realized by the frictional force between the brake shoe and the brake drum, and the magnitude of the brake braking torque substantially represents the magnitude of the frictional force. When the brake is braked, the brake shoe drives the brake shoe shaft to make an appropriate small displacement in the long circular shaft hole of the brake arm, and the direction of the displacement coincides with the direction of the frictional force generated by the brake shoe applying normal pressure, and the magnitude of the displacement is directly proportional to the magnitude of the frictional force. Therefore, by installing the sensing plate and the tensile pressure sensor, the displacement amount of the brake shoe shaft in the long circular shaft hole of the brake arm can be detected, and the displacement amount can be converted into detection data that can reflect the magnitude of the frictional force, thereby realizing real-time detection of the brake frictional force. Furthermore, the magnitude of the brake braking torque can be detected in relation to the radius of the device brake drum (i.e., the moment arm of the frictional force). Therefore, the sensing plate and the tensile pressure sensor added to the brake constitute a braking torque detection device.

[0010] In the present invention, the axial hole of the brake shoe shaft in the brake arm is opened as a long, upright circular axial hole, and the brake arm is stably connected to the brake shoe shaft via the sensing plate, so that the brake shoe shaft is suspendedly connected to the brake arm via the sensing plate. In this way, when the brake is applied, a displacement amount that changes with the change in the magnitude of the braking friction force is generated in the brake shoe shaft, and the sensing plate can effectively detect this displacement amount. The detected braking displacement amount is converted into the plate deformation of the sensing plate, and the tensile pressure sensor converts this plate deformation into an electrical signal of the magnitude of the received force and transmits it to the outside, thereby realizing real-time detection of the braking friction force and also real-time detection of the brake braking torque.

[0011] In the present invention, a wear-resistant bar is added to the long circular shaft hole of the brake arm, or a wear-resistant bar is added to the brake arm via a support plate, so that when the brake arm is braking, a braking normal pressure is applied to the brake shoe shaft through the wear-resistant bar. Furthermore, the wear-resistant bar can be hardened and its hardness meets the usage requirements, so that the braking displacement of the brake shoe shaft in the long circular shaft hole does not generate an impression groove in the wear-resistant bar. This eliminates the adverse effect of the impression groove on the braking displacement of the brake shoe shaft and accordingly reduces the detection deviation of the braking torque.

[0012] In particular, by adding an axle sleeve to the brake shoe shaft, the sliding displacement of the brake shoe shaft in the long circular axle hole of the brake arm is converted into rolling displacement of the axle sleeve on the wear-resistant bar, and the sliding friction is converted into rolling friction.By this, the frictional force generated from the braking displacement of the brake shoe shaft against the wear-resistant bar due to the braking normal pressure acting on the brake shoe shaft is reduced due to a significant reduction in the friction coefficient.As this frictional force becomes much smaller than the braking frictional force due to brake braking, the adverse effect of this frictional force on the braking frictional force of the brake is reduced, and the detection accuracy of the brake braking frictional force and braking torque by the braking torque detection device is effectively improved.

[0013] Another possible embodiment of the present invention is a drum-type brake comprising a brake arm, a brake shoe, a base and a braking torque detection device, wherein the brake shoe is hingedly connected to the brake arm via a brake shoe shaft, the brake arm has a long circular shaft hole through which the brake shoe shaft passes, a support plate is installed on the brake arm, a through hole is opened in a plate surface of the support plate, the long circular shaft hole is within the opening range of the through hole, and a wear-resistant bar is installed on an opening edge of the through hole in the support plate to press against the brake shoe shaft when the brake is applied, and the braking torque detection device comprises a sensing plate and a tensile pressure sensor installed on the sensing plate, one end of the sensing plate is connected to the brake shoe shaft and the other end of the sensing plate is connected to the brake arm.

[0014] The sensing plate is installed vertically, has one end having a hole and connected to the brake arm via a connecting shaft, and has the other end having a closed hole or an open groove, the brake shoe shaft passes through the closed hole or the open groove, and the axis of the brake shoe shaft is located at the longitudinal center of the long circular shaft hole in a static state.

[0015] A shaft sleeve is provided around the brake shoe shaft, and the shaft sleeve abuts against the wear bar.

[0016] A fixing sheet is provided on the outer surface of the support plate to seal the wear bar.

[0017] Another possible embodiment of the present invention is a drum-type brake comprising a brake arm, a brake shoe, a base and a braking torque detection device, the brake arm being hingedly connected to the base via a hinge shaft, the brake arm having a shaft hole through which the hinge shaft passes which is a long circular shaft hole, a wear-resistant bar that presses against the hinge shaft when the brake is applied is installed on one side wall of the long circular shaft hole, the braking torque detection device comprising a sensing plate and a tensile pressure sensor installed on the sensing plate, a lower end of the sensing plate being connected to the hinge shaft and an upper end of the sensing plate being connected to the brake arm.

[0018] A shaft sleeve is provided around the hinge shaft, and the shaft sleeve abuts against the wear-resistant bar.

[0019] Another possible embodiment of the present invention is a drum-type brake comprising a brake arm, a brake shoe, a base and a braking torque detection device, the brake arm being hingedly connected to the base via a hinge shaft, the brake arm having an axial hole through which the hinge shaft passes which is a long circular axial hole, a support plate is provided on the brake arm, a through hole is provided on a plate surface of the support plate, the long circular axial hole is within an opening range of the through hole, and a wear-resistant bar is provided on an opening edge of the through hole in the support plate for pressing the hinge shaft when the brake is applied, the braking torque detection device comprising a sensing plate and a tensile pressure sensor provided on the sensing plate, a lower end of the sensing plate is connected to the hinge shaft and an upper end of the sensing plate is connected to the brake arm.

[0020] A shaft sleeve is provided around the hinge shaft, and the shaft sleeve abuts against the wear-resistant bar.

[0021] In the latter two embodiments, a wear-resistant bar is added to the shaft hole of the base hinge shaft of the brake arm, or a wear-resistant bar is added to the brake arm via a support plate, thereby eliminating the impression groove formed in the long circular shaft hole due to the braking displacement of the hinge shaft, thereby reducing the detection deviation of the braking torque. Similarly, by adding a shaft sleeve to the hinge shaft, the sliding displacement of the hinge shaft in the long circular shaft hole of the brake arm during braking is converted into rolling displacement of the shaft sleeve at the wear-resistant bar, and by converting sliding friction into rolling friction, the adverse effect of the braking displacement friction force of the hinge shaft on the braking friction force is reduced, and the detection accuracy of the braking friction force and braking torque of the braking torque detection device is effectively improved. [Brief description of the drawings]

[0022] [Figure 1] FIG. 2 is a schematic diagram of the external structure of the product according to the first and second embodiments. [Diagram 2] FIG. 11 is a structural schematic diagram of the second embodiment. [Diagram 3] 3 is a partial cross-sectional view of the drum brake shown in FIG. 2 taken along the line AA. [Figure 4]3 is a partial cross-sectional view of the drum brake shown in FIG. 2 taken along the arrow BB. [Diagram 5] 3 is a partial enlarged view of a portion C of the drum brake shown in FIG. 2. [Figure 6] 3 is a partial enlarged view of a portion D of the drum brake shown in FIG. 2. [Figure 7] FIG. 2 is a schematic diagram of the structure of one sensing plate. [Figure 8] FIG. 4 is a schematic diagram of the structure of another sensing plate. [Figure 9] FIG. 2 is a schematic diagram showing the structure of a brake arm. [Figure 10] FIG. 11 is a schematic diagram of the external structure of the product according to the third and fourth embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] 1 and 2, a typical drum brake includes a brake arm 1, a brake shoe 8, and a base 17, and the brake arm 1 is connected at its lower end to the base 17 via a hinge shaft 18 and at its upper end to a brake rod, a brake spring, a brake electromagnet, etc., and a shaft hole 3 (FIG. 9) is opened in the center of each of the two brake arms 1, and one brake shoe shaft 2 is inserted into each shaft hole 3 to connect the brake shoes 8 by a hinge. The brake shoes 8 connected to the two brake arms are installed facing each other, and a brake drum 10 attached to a device is sandwiched between them.

[0024] The drum brake of the present invention is constructed by slightly modifying a normal drum brake and adding a braking torque detection device. The braking torque detection device includes a sensing plate 4 and a tensile pressure sensor installed on the sensing plate 4.

[0025] Example 1 As shown in Fig. 9, the specific structure of the brake arm 1 according to this embodiment is a long, upright circular shaft hole 3 opened in the brake arm body and through which the brake shoe shaft passes, and a wear-resistant bar 13 is installed on one side of the hole wall of the long, circular shaft hole. The side on which the wear-resistant bar 13 is installed is the side that can press and push the brake shoe shaft when the brakes are applied.

[0026] As shown in FIGS. 2 and 4, the sensing plate 4 in the braking torque detection device is installed vertically, with its lower end connected to the brake shoe shaft 2 and its upper end suspended from the brake arm 1 via a connecting shaft 9.

[0027] As shown in FIGS. 3, 4 and 5, a shaft sleeve 15 is provided around the brake shoe shaft 2, and the shaft sleeve 15 slides on the brake shoe shaft 2 and abuts against the exposed surface of the wear-resistant bar 13 in the shaft hole 3.

[0028] Example 2 As shown in Fig. 9, the specific structure of the brake arm 1 according to this embodiment is such that the shaft hole 3, which is opened in the brake arm body and through which the brake shoe shaft passes, is a long, upright circular shaft hole, the support plate 11 is fixed to the front and rear outer surfaces of the brake arm body, a through hole (Fig. 6) is opened in the plate surface of the support plate 11, the long circular shaft hole in the brake arm 1 is within the opening range of the through hole, and a wear-resistant bar 13 is installed on the inner edge of one side of the hole edge of the through hole, and the side on which the wear-resistant bar 13 is installed is the side that can press and push the brake shoe shaft when braking. The wear-resistant bar 13 may be of the same thickness as the support plate 11, and the outer surface is flush with the outer surface of the support plate 11 (Fig. 3), and the longitudinal direction of the wear-resistant bar 13 and the longitudinal direction of the long circular shaft hole 3 are the same. A fixing sheet 16 (Fig. 3) that seals the wear-resistant bar is installed on the outer surface of the support plate 11.

[0029] The present embodiment is a brake arm 1 utilizing the above-described structure, and further includes an additional braking torque detector in the brake.

[0030] 2 and 4, the sensing plate 4 in the braking torque detection device is installed vertically with its lower end connected to the brake shoe shaft 2 and its upper end suspended from the brake arm 1 via a connecting shaft 9. As shown in Figures 3, 4 and 5, a shaft sleeve 15 is provided around the brake shoe shaft 2, and the shaft sleeve 15 slides on the brake shoe shaft 2 and faces the wear-resistant bar 13 so as to abut against the wear-resistant bar 13.

[0031] As shown in Figures 7 and 8, the specific structure of the sensing plate 4 is a rectangular plate body with two slits parallel to the short side of the plate body along the long side, and the opening directions of the two slits are opposite to each other, so that the plate surface of the sensing plate is divided into three parts that are relatively independent but connected sequentially, and the sensing plate 4 forms an S-shaped plate body with a rectangular outline. The plate body of the sensing plate 4 is provided with a closed hole 5 (Figure 7) or an open groove 6 (Figure 8) around the brake shoe shaft. The closed hole 5 may be a circular hole whose diameter is slightly larger than the diameter of the brake shoe shaft, or a long circular hole whose circle radius is slightly larger than the radius of the brake shoe shaft. The longitudinal direction of the long circular hole and the longitudinal direction of the long circular shaft hole 3 of the brake arm after the sensing plate 4 is attached to the brake arm 1 are perpendicular to each other, so that the horizontal displacement component of the brake shoe shaft during braking is eliminated, and the vertical displacement component in the braking tangential direction of the brake shoe shaft is obtained for detecting the braking friction force and braking torque. The tensile pressure sensor 7 is fixed at the center position (FIG. 5) of the surface of the sensing plate, which is the optimum position for generating plate deformation in the sensing plate.

[0032] In FIG. 4, the sensing plate 4 is suspended in the middle gap of the brake arm 1 via a connecting shaft 9, and the longitudinal centerline of the sensing plate 4 and the longitudinal centerline of the long circular shaft hole 3 in the brake arm 1 are in the same vertical plane (FIG. 2).

[0033] 2 and 4, the sensing plate 4 is installed vertically, with its upper end suspended in the intermediate gap of the brake arm 1 and its lower end mounted around the brake shoe shaft 2 via a closed hole 5 or an open groove 6, and the axis of the brake shoe shaft 2 is in the longitudinal center of the shaft hole 3 in the brake arm 1 in a static state. Thus, a stable supporting and connecting relationship is formed between the brake shoe shaft 2 and the brake arm 1 via the sensing plate 4 in the braking torque detection device, and a suspended connection is realized between the brake shoe shaft 2 and the brake arm 1. The longitudinal center line of the sensing plate 4 and the longitudinal center line of the shaft hole 3 in the brake arm 1 are on the same vertical plane, which better guarantees the detection accuracy.

[0034] When the brake is applied, a braking displacement occurs in the brake shoe shaft 2 at the shaft hole 3 of the brake arm 1 and the closed hole 5 of the sensing plate 4. The braking displacement can be decomposed into a lateral displacement and a longitudinal displacement. The lateral displacement is eliminated by the long circular closed hole 5 (or open groove 6) of the sensing plate 4, and the longitudinal displacement is eliminated by the long circular axial hole of the brake arm 1. As a result, the brake shoe shaft 2 can generate a displacement amount that changes according to the magnitude of the braking friction force along the longitudinal direction of the brake arm 1 during braking. As the longitudinal displacement is eliminated, a corresponding plate deformation occurs in the sensing plate 4. The tensile pressure sensor 7 is fixed to a portion of the center of the plate surface of the sensing plate 4 that is easy to sense, so that the plate deformation generated in the sensing plate 4 due to the braking force can be converted into force information, and the force information can be transmitted to the outside as an electrical signal or a digital signal. The force received information may be regarded as the frictional force generated during braking, and the product of the braking frictional force and the radius of the brake drum (that is, the moment arm of the frictional force) is the true value of this drum brake braking torque.

[0035] Example 3 As shown in Fig. 10, the structure of the brake according to this embodiment is almost the same as that of embodiment 1, but the main difference is that the shaft hole in the brake arm 1 that is hingedly connected to the base 17 is changed to an upright long circular shaft hole, and a wear-resistant bar 13 is installed on one side of the hole wall of the long circular shaft hole, and the side on which the wear-resistant bar 13 is installed is the side that can press the hinge shaft 18 when the brake is applied. The braking torque detection device includes a sensing plate 4 and a tensile pressure sensor 7 installed on the sensing plate 4. The lower end of the sensing plate 4 is connected to the hinge shaft 18, and the upper end of the sensing plate 4 is connected to the brake arm 1. The operation mode and operation mechanism of the braking torque detection device are the same as those of embodiment 1.

[0036] A shaft sleeve 15 is fitted around a hinge shaft 18 that penetrates through the base 17. The shaft sleeve 15 slides over the hinge shaft 18 and abuts against the exposed surface of the wear-resistant bar 13 in the shaft hole.

[0037] Example 4 As shown in FIG. 10, the brake structure according to this embodiment is almost the same as that of the second embodiment, but the main difference is that the shaft hole in the brake arm 1 that is hinged to the base 17 is changed to a vertical long circular shaft hole. As shown in FIG. 6, the support plate 11 is fixed to the outer surface of the long circular shaft hole in the brake arm 1, a through hole is opened in the plate surface of the support plate 11 (see FIG. 6), the long circular shaft hole in the brake arm 1 is within the opening range of the through hole, and a wear-resistant bar 13 is installed on the inner edge of one side of the hole edge of the through hole, and the side on which the wear-resistant bar 13 is installed is the side that can press the hinge shaft when braking. The wear-resistant bar 13 may be of the same thickness as the support plate 11, and the outer surface is flush with the outer surface of the support plate 11 (see FIG. 3), and the longitudinal direction of the wear-resistant bar 13 coincides with the longitudinal direction of the long circular shaft hole. A fixing sheet 16 that seals the wear-resistant bar is installed on the outer surface of the support plate 11 (see FIG. 3).

[0038] 5, the shaft sleeve 15 is fitted around the hinge shaft 18 that penetrates the base 17, and the two fit together in a sliding manner. The shaft sleeve 15 faces the hinge shaft 17 so that the shaft sleeve 15 abuts against the wear-resistant bar 13.

[0039] The braking torque detection device used in this embodiment is almost the same as that in the second embodiment, but the sensing plate 4 is changed to one that is attached between the brake 1 and the hinge shaft 18 that penetrates the base and detects the braking torque of the brake in real time. The operation mechanism is that the brake arm 1 is suspended and connected to the hinge shaft 18 via the sensing plate 4, and when the brake shoe 8 applies the brake to the brake drum 10, the vertical tension generated in the brake arm 1 by the braking friction force is detected by the sensing plate 1, the braking friction force is detected by the tension pressure sensor 7, and real-time detection data of the braking torque can be obtained in relation to the moment arm of the braking friction force (the radius of the brake drum). [Explanation of symbols]

[0040] 1 Brake arm 2 Brake shoe shaft 3 Shaft hole 4 Sensing plate 5 Obturator foramen 6 Opening groove 7 Tensile Pressure Sensor 8 Brake shoes 9 Connecting shaft 10 Brake drum 11 Support plate 13 Wear-resistant bar 15 Shaft sleeve 16 Fixed seat 17 Base 18 Hinge axis

Claims

1. A brake arm, a brake shoe, a base, and a braking torque detection device are included. A drum brake in which the brake shoe is hinged to the brake arm via a brake shoe shaft, a shaft hole in the brake arm through which the brake shoe shaft passes is an elliptical shaft hole, and a wear-resistant bar is installed on one side of the hole wall of the elliptical shaft hole to press the brake shoe shaft when braking; The braking torque detection device includes a sensing plate and a tensile pressure sensor installed on the sensing plate, one end of the sensing plate is connected to the brake shoe shaft and the other end of the sensing plate is connected to the brake arm, A shaft sleeve is provided around the brake shoe shaft, and the shaft sleeve abuts against the wear-resistant bar, thereby converting the sliding displacement of the brake shoe shaft in the oval shaft hole of the brake arm into a rolling displacement of the shaft sleeve on the wear-resistant bar during braking. Drum brake.

2. the sensing plate is installed in a vertical direction, one end of which has a hole and is connected to the brake arm via a connecting shaft, and the other end of which has a closed hole or an open groove, the brake shoe shaft passes through the closed hole or the open groove, and the axis of the brake shoe shaft is located at the longitudinal center of the oval shaft hole in a static state; 2. The drum brake according to claim 1.

3. A brake arm, a brake shoe, a base, and a braking torque detection device are included. A drum brake in which the brake shoe is hinged to the brake arm via a brake shoe shaft, a shaft hole in the brake arm through which the brake shoe shaft passes is an oval shaft hole, a support plate is installed on the brake arm, a through hole is opened in a plate surface of the support plate, the oval shaft hole is within an opening range of the through hole, and a wear-resistant bar is installed on an opening edge of the through hole in the support plate to press against the brake shoe shaft during braking, The braking torque detection device includes a sensing plate and a tensile pressure sensor installed on the sensing plate, one end of the sensing plate is connected to the brake shoe shaft and the other end of the sensing plate is connected to the brake arm, A shaft sleeve is provided around the brake shoe shaft, and the shaft sleeve abuts against the wear-resistant bar, thereby converting the sliding displacement of the brake shoe shaft in the oval shaft hole of the brake arm into a rolling displacement of the shaft sleeve on the wear-resistant bar during braking. Drum brake.

4. the sensing plate is installed in a vertical direction, one end of which has a hole and is connected to the brake arm via a connecting shaft, and the other end of which has a closed hole or an open groove, the brake shoe shaft passes through the closed hole or the open groove, and the axis of the brake shoe shaft is located at the longitudinal center of the oval shaft hole in a static state; 4. The drum brake according to claim 3.

5. A fixing sheet is provided on the outer surface of the support plate to seal the wear bar; 4. The drum brake according to claim 3.

6. A brake arm, a brake shoe, a base, and a braking torque detection device are included. A drum brake in which the brake arm is hinged to the base via a hinge shaft, The brake arm has an oval shaft hole through which the hinge shaft passes, and a wear-resistant bar is provided on one side of the oval shaft hole to press the hinge shaft when the brake is applied. The braking torque detection device includes a sensing plate and a tensile pressure sensor installed on the sensing plate, the lower end of the sensing plate is connected to the hinge shaft, and the upper end of the sensing plate is connected to the brake arm, a shaft sleeve is provided around the hinge shaft, and the shaft sleeve abuts against the wear-resistant bar, thereby converting a sliding displacement of the hinge shaft in the oval shaft hole of the brake arm into a rolling displacement of the shaft sleeve on the wear-resistant bar during braking; Drum brake.

7. A brake arm, a brake shoe, a base, and a braking torque detection device are included. A drum brake in which the brake arm is hinged to the base via a hinge shaft, a shaft hole in the brake arm through which the hinge shaft passes is an oval shaft hole, a support plate is provided on the brake arm, a through hole is provided on a plate surface of the support plate, the oval shaft hole is within an opening range of the through hole, and a wear-resistant bar is provided on an opening edge of the through hole in the support plate to press against the hinge shaft when braking; The braking torque detection device includes a sensing plate and a tensile pressure sensor installed on the sensing plate, the lower end of the sensing plate is connected to the hinge shaft, and the upper end of the sensing plate is connected to the brake arm, a shaft sleeve is provided around the hinge shaft, and the shaft sleeve abuts against the wear-resistant bar, thereby converting a sliding displacement of the hinge shaft in the oval shaft hole of the brake arm into a rolling displacement of the shaft sleeve on the wear-resistant bar during braking; Drum brake.

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