Drum type brake shoe abrasion alarm device and brake shoe abrasion monitoring method

Abstract

The invention provides a drum-type brake shoe abrasion alarm device and a brake shoe abrasion monitoring method. According to the alarm device, an abrasion sensor is fixedly installed on a sleeve of a cam shaft, and a long inner groove is machined in the position, opposite to the abrasion sensor, of the cam shaft; the sensing end of the abrasion sensor extends into the long inner groove and is close to the starting end of the long inner groove, the length of the long inner groove is set according to the abrasion control amount, and when the tail end protrusion of the long inner groove is controlled to touch the sensing end of the abrasion sensor, the abrasion sensor sends out a signal to give an alarm. By means of the structural design, the sensor does not swing in the working process and does not need to bear high temperature generated by braking, the influence of cam shaft deformation on abrasion monitoring precision can be greatly reduced, and the accuracy and durability of brake shoe abrasion alarming are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of automotive braking technology and relates to brake pad wear monitoring, specifically to a drum brake pad wear alarm device and a brake pad wear monitoring method. Background Technology

[0002] Currently, brake pad wear sensors for medium and heavy-duty trucks use either embedded wire wear sensors or integrated sensors with adjusting arms. Embedded wire wear sensors are installed inside the brake pads, requiring segmented wiring harnesses. However, segmented harnesses are prone to problems such as connector detachment, water ingress, and mud buildup at the connector points, leading to numerous wiring harness issues. Furthermore, because the sensor is embedded in the brake pads, it operates under high temperatures generated by braking, causing premature aging and damage to both the sensor and the wiring harness. Moreover, the frequent movement of the sensor with the brake pads makes the wiring harness prone to wear and breakage at the points where it passes through the base plate and dust cover, resulting in poor durability and frequent harness breakage.

[0003] The integrated sensor on the adjusting arm is installed along with the adjusting arm, meaning it can only be installed and replaced along with the adjusting arm, resulting in excessively high costs for brake pad wear warning devices. Furthermore, frequent swaying during braking can easily damage the sensor wiring harness. Also, because the integrated sensor is installed at the initial end of the camshaft, and camshafts vary in length, longer camshafts experience greater rigid torsional deformation during operation. This means the actual sway amplitude of the adjusting arm during braking will exceed the theoretical amplitude due to the clearance and rigid deformation of the braking components, significantly reducing sensor signal accuracy and affecting driver judgment.

[0004] Chinese patent CN 110469606 A discloses a drum-type heavy-duty brake pad wear monitoring sensor, alarm system, and wear monitoring method. The wear monitoring sensor includes a rotating disk, an inner shell, and an outer shell, with the inner shell and outer shell fixedly connected, forming a cavity in the middle for placing the rotating disk. The rotating disk is fixed on the camshaft of the brake and rotates synchronously with the camshaft. A metal ring is fixed on the rotating disk, and the metal ring includes a metal ring and several metal teeth distributed on the metal ring. The inner shell is equipped with a first metal contact and a second metal contact. The first metal contact corresponds to the metal ring in contact, and the second metal contact corresponds to the metal teeth. Depending on the rotational position of the metal ring, the contact with the metal teeth is sometimes present and sometimes absent. The metal contacts are connected to a counting sensor to achieve real-time monitoring of brake pad wear. However, because it is mounted on the camshaft, and the camshaft has a rigid torsional deformation, the accuracy of this monitoring method still needs to be improved. Summary of the Invention

[0005] To solve the above technical problems, this invention breaks with the traditional sensor installation method. The sensor is installed on a sleeve near the end of the camshaft, and a long inner groove is machined on the camshaft. When the protrusion at the end of the long inner groove touches the sensing end of the wear sensor, the wear sensor sends a signal to trigger an alarm. This structural design allows the sensor to operate without swaying, without having to withstand the high temperature generated by braking, and can also greatly reduce the impact of camshaft deformation on the wear monitoring accuracy, significantly improving the accuracy and durability of brake pad wear alarm.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A drum brake pad wear alarm device includes a camshaft mounted on a brake base plate, a sleeve near the end of the camshaft (S-axis end) and fitted onto the camshaft for supporting the camshaft, and a wear sensor. The initial end of the camshaft is connected to an automatic adjustment arm, which continuously adjusts as the brake pads wear, thereby keeping the gap between the brake pads and the brake drum constant. The camshaft can rotate relative to the sleeve. The S-axis end of the camshaft is used to drive the brake pads to contact the brake drum to achieve braking. The improvement is that the wear sensor is mounted and fixed on the sleeve. A long inner groove is machined on the camshaft at a position opposite to the wear sensor. The sensing end of the wear sensor extends into the long inner groove and is close to the starting end of the long inner groove. The length of the long inner groove is set according to the wear control amount. When the protruding end of the long inner groove touches the sensing end of the wear sensor, the wear sensor sends a signal to trigger an alarm.

[0007] As a preferred embodiment of the present invention, the sleeve is provided with a mounting hole at the location where the wear sensor is installed. The sensing end of the wear sensor is disposed in the mounting hole and extends into the long inner groove. The wear sensor is fixed to the sleeve by screws.

[0008] As a preferred embodiment of the present invention, the wiring harness of the wear sensor is seamlessly connected to the original vehicle, and the fixing point of the wear sensor can be arbitrarily arranged according to the brake space and the wiring harness routing.

[0009] As a preferred embodiment of the present invention, the angle α between the end protrusion of the long inner groove and the fixing point of the wear sensor is an acute angle.

[0010] The present invention also provides a method for monitoring the wear of drum brake pads, the method comprising the following steps: Step S1. Install and fix the wear sensor on the sleeve of the camshaft. The initial end of the camshaft is connected to the automatic adjustment arm. The automatic adjustment arm continuously adjusts as the brake shoes wear, so that the gap between the brake shoes and the brake drum remains constant. The camshaft can rotate relative to the sleeve. The S-axis end of the camshaft is used to drive the brake shoes to contact the brake drum to achieve braking. Step S2. A long inner groove is machined at the position opposite to the wear sensor on the camshaft, so that the sensing end of the wear sensor extends into the long inner groove and is close to the starting end of the long inner groove. The length of the long inner groove is set according to the wear control amount. Step S3. During braking, control the camshaft to rotate at a fixed angle and make the end protrusion of the long inner groove rotate toward the wear sensor. As the brake pads are worn, the automatic adjustment arm continuously adjusts accordingly, and the S-axis end of the camshaft that drives the brake pads also continuously changes displacement. This causes the end protrusion of the long inner groove to continuously approach the wear sensor after the camshaft rotates at a fixed angle. When the end protrusion of the long inner groove touches the sensing end of the wear sensor, the wear sensor sends a signal to trigger an alarm. Step S4. The wear indicator light illuminates, prompting the operator to replace the brake pads.

[0011] Advantages and beneficial effects of the present invention: (1) The alarm device provided by the present invention breaks the traditional sensor installation method. The sensor is installed on a sleeve near the end of the camshaft. A long inner groove is machined on the camshaft at the position opposite to the wear sensor. When the end protrusion of the long inner groove touches the sensing end of the wear sensor, the wear sensor sends a signal to alarm. This structural design can make the sensor swing without the need to withstand the high temperature generated by braking during operation. It can also greatly reduce the influence of camshaft deformation on the wear monitoring accuracy and significantly improve the accuracy and durability of brake pad wear alarm.

[0012] (2) The wiring harness of the wear sensor of the alarm device provided by the present invention is connected to the original vehicle without damage, and the fixing point of the wear sensor can be arbitrarily arranged according to the brake space and the wiring harness direction, making the arrangement more flexible and having advantages such as simple structure, high reliability and small space ratio.

[0013] (3) The wear sensor in the alarm device provided by the present invention is equivalent to an inductive switch. It can be used continuously without damage. Compared with the existing buried wire wear sensor or the adjustment arm integrated sensor, the cost of the alarm device is lower. Attached Figure Description

[0014] Figure 1 This is an isometric view of the camshaft of the present invention; Figure 2 This is a schematic diagram of the installation of the alarm device of the present invention. Figure 1 ; Figure 3 This is a schematic diagram of the installation of the alarm device of the present invention. Figure 2 ; Figure 4 This is a schematic diagram showing the displacement of the brake shoe of the present invention as the S end of the camshaft wears. Detailed Implementation

[0015] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0016] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0017] like Figures 1 to 4 As shown, this embodiment provides a drum brake pad wear alarm device, including a camshaft 1 installed on the brake base plate, a sleeve 2 near the end of the camshaft (S-axis end) and fitted on the camshaft 1 for supporting the camshaft, and a wear sensor 3. The initial end of the camshaft 1 is connected to an automatic adjustment arm (not shown). The automatic adjustment arm continuously adjusts as the brake pads wear, thereby keeping the gap between the brake pads and the brake drum constant. The camshaft 1 can rotate relative to the sleeve 2, and the S-axis end of the camshaft is used to drive the brake pads to contact the brake drum to achieve braking. The improvement is that the wear sensor 3 is installed and fixed on the sleeve 2. A long inner groove 101 is machined on the camshaft 1 at a position opposite to the wear sensor 3. The sensing end of the wear sensor 3 extends into the long inner groove and is close to the starting end of the long inner groove. The length of the long inner groove is set according to the wear control amount. When the end protrusion a of the long inner groove touches the sensing end of the wear sensor, the wear sensor sends a signal to alarm.

[0018] It should be noted that the wear sensor 3 described in this embodiment is directly installed in an existing pneumatic drum brake system. The specific connection methods between the automatic adjusting arm and the camshaft 1, the sleeve and the camshaft, and how the automatic adjusting arm maintains the clearance between the brake shoes and the brake drum are all existing technologies and are not improvements in this application; therefore, they will not be described in detail. The key aspect of this application is that by improving the structure of the camshaft and the installation position of the sensor, the sensor can trigger a wear alarm by utilizing the displacement changes of the camshaft during brake shoe wear.

[0019] Furthermore, in this embodiment, the sleeve 2 is machined with a mounting hole at the position where the wear sensor is installed, the sensing end of the wear sensor 3 is set in the mounting hole, and the wear sensor 3 is fixed to the sleeve 2 by screws.

[0020] Furthermore, in this embodiment, the wiring harness of the wear sensor 3 is seamlessly connected to the original vehicle, and the fixing point of the wear sensor 3 is arbitrarily arranged according to the brake space and the wiring harness direction.

[0021] Furthermore, in this embodiment, the angle α between the end protrusion a of the long inner groove 101 and the fixing point of the wear sensor 3 is an acute angle.

[0022] This embodiment also provides a method for monitoring the wear of drum brake pads, the method comprising the following steps: Step S1. Install and fix the wear sensor on the sleeve of the camshaft. The initial end of the camshaft is connected to the automatic adjustment arm. The automatic adjustment arm continuously adjusts as the brake shoes wear, so that the gap between the brake shoes and the brake drum remains constant. The camshaft can rotate relative to the sleeve. The S-axis end of the camshaft is used to drive the brake shoes to contact the brake drum to achieve braking. Step S2. A long inner groove is machined at the position opposite to the wear sensor on the camshaft, so that the sensing end of the wear sensor extends into the long inner groove and is close to the starting end of the long inner groove. The length of the long inner groove is set according to the wear control amount. Step S3. During braking, control the camshaft to rotate at a fixed angle and make the end protrusion of the long inner groove rotate toward the wear sensor. As the brake pads are worn, the automatic adjustment arm continuously adjusts accordingly, and the S-axis end of the camshaft that drives the brake pads also continuously changes displacement. This causes the end protrusion of the long inner groove to continuously approach the wear sensor after the camshaft rotates at a fixed angle. When the end protrusion of the long inner groove touches the sensing end of the wear sensor, the wear sensor sends a signal to trigger an alarm. Step S4. The wear indicator light illuminates, prompting the operator to replace the brake pads.

[0023] The alarm device provided in this embodiment enables the sensor to operate without swaying, without having to withstand the high temperatures generated by braking, and can also greatly reduce the impact of camshaft deformation on the accuracy of wear monitoring. It significantly improves the accuracy and durability of brake pad wear alarm, and has advantages such as simple structure, high reliability, small space occupation, low cost, higher accuracy, and better durability.

[0024] The above describes specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A drum brake pad wear alarm device, comprising a camshaft mounted on a brake backing plate, an S-axis end near the camshaft and fitted onto the camshaft for supporting the camshaft, and a wear sensor; the initial end of the camshaft is connected to an automatic adjustment arm, which continuously adjusts as the brake pads wear, thereby maintaining a constant gap between the brake pads and the brake drum; the camshaft can rotate relative to the sleeve; and the S-axis end of the camshaft drives the brake pads to contact the brake drum to achieve braking; characterized in that: The wear sensor is mounted and fixed on the sleeve. A long inner groove is machined on the camshaft at a position opposite to the wear sensor. The sensing end of the wear sensor extends into the long inner groove and is close to the starting end of the long inner groove. The length of the long inner groove is set according to the wear control amount. When the end protrusion of the long inner groove touches the sensing end of the wear sensor, the wear sensor sends a signal to trigger an alarm.

2. The drum brake pad wear alarm device according to claim 1, characterized in that: The sleeve has a mounting hole at the location where the wear sensor is installed. The sensing end of the wear sensor is set in the mounting hole and extends into the long inner groove. The wear sensor is fixed to the sleeve by screws.

3. The drum brake pad wear alarm device according to claim 1, characterized in that: The wiring harness of the wear sensor is seamlessly connected to the original vehicle, and the fixing point of the wear sensor can be arbitrarily arranged according to the brake space and the wiring harness direction.

4. The drum brake pad wear alarm device according to claim 1, characterized in that: The angle α between the protruding end of the long inner groove and the fixing point of the wear sensor is an acute angle.

5. A method for monitoring wear of drum brake pads, characterized in that: The method includes the following steps: Step S1. Install and fix the wear sensor on the sleeve of the camshaft. The initial end of the camshaft is connected to the automatic adjustment arm. The automatic adjustment arm continuously adjusts as the brake shoes wear, so that the gap between the brake shoes and the brake drum remains constant. The camshaft can rotate relative to the sleeve. The S-axis end of the camshaft is used to drive the brake shoes to contact the brake drum to achieve braking. Step S2. A long inner groove is machined at the position opposite to the wear sensor on the camshaft, so that the sensing end of the wear sensor extends into the long inner groove and is close to the starting end of the long inner groove. The length of the long inner groove is set according to the wear control amount. Step S3. During braking, control the camshaft to rotate at a fixed angle and make the end protrusion of the long inner groove rotate toward the wear sensor. As the brake pads are worn, the automatic adjustment arm continuously adjusts accordingly, and the S-axis end of the camshaft that drives the brake pads also continuously changes displacement. This causes the end protrusion of the long inner groove to continuously approach the wear sensor after the camshaft rotates at a fixed angle. When the end protrusion of the long inner groove touches the sensing end of the wear sensor, the wear sensor sends a signal to trigger an alarm. Step S4. The wear indicator light illuminates, prompting the operator to replace the brake pads.

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