Self-adjusting anti-sticking device for air disc brake of commercial vehicle

Abstract

This invention relates to the field of commercial vehicle braking system technology and discloses a self-adjusting anti-jamming device for commercial vehicle air disc brakes, including a brake caliper, a brake push rod, a self-adjusting transmission unit, a redundant gap adjustment unit, a self-cleaning protection unit, and an adaptive preload unit. This invention constructs a three-stage progressive anti-jamming structure: the first stage achieves overload protection through the multi-stage friction unloading structure of the self-adjusting transmission unit, reducing the risk of rigid jamming of the transmission pair; the second stage achieves redundancy in the gap adjustment function through the dual-path transmission of the redundant gap adjustment unit, avoiding functional failure due to single-path jamming; the third stage, through the cooperation of the self-cleaning protection unit and the adaptive preload unit, reduces the probability of jamming due to environmental impurities and maintains a better preload state, effectively improving the anti-jamming capability of the self-adjusting mechanism of the air disc brake and adapting to various complex operating conditions of commercial vehicle air disc brake systems.

Description

Technical Field

[0001] This invention belongs to the technical field of commercial vehicle braking systems, and particularly relates to a self-adjusting clearance and anti-jamming device for commercial vehicle air disc brakes. Background Technology

[0002] Air disc brakes, with their advantages of good braking stability and strong heat dissipation, have been widely used in the braking systems of medium and heavy-duty commercial vehicles. The automatic clearance adjustment mechanism is the core component of the air disc brake, used to compensate for the wear clearance between the brake pads and the brake disc in real time, ensuring stable braking stroke.

[0003] Chinese utility model patent CN203614638U discloses a self-adjusting device for preventing misalignment of the gap in a pneumatic disc brake. It includes a self-adjusting shaft, a shift fork, a conical spring, and a fixed disc. The conical spring's buffering effect prevents misalignment and improves the reliability of the self-adjusting mechanism to a certain extent. Chinese invention patent CN105465248A discloses a brake gap adjustment device and a pneumatic disc brake. It uses a sprocket and chain drive to achieve synchronous gap adjustment of the two push rods, optimizing the synchronization of the gap adjustment.

[0004] However, in practical and complex working conditions, existing self-adjusting mechanisms still have the following shortcomings:

[0005] First, the overload protection capability is insufficient, and transmission jamming is prone to occur. The existing self-adjusting mechanism's unidirectional transmission pair mostly adopts a rigid meshing structure, and only a single conical spring is used for buffering. When the braking impact is too large or the clearance resistance is abnormal, the transmission pair is prone to jamming faults such as stress concentration and tooth surface seizing. Moreover, the buffering threshold cannot be adjusted according to the working conditions, and the adaptability range is limited.

[0006] Second, the adjustment path is singular, leading to a higher risk of functional failure. Existing self-adjusting mechanisms generally use a single path for clearance compensation transmission. When the main transmission path fails due to wear, impurities, or other reasons, the self-adjusting function is prone to complete failure, resulting in a continuous increase in braking clearance, a longer braking stroke, and compromised vehicle braking safety.

[0007] Third, it has poor environmental adaptability, and impurities can easily cause jamming. Commercial vehicles operate under complex conditions, and impurities such as dust and mud can easily enter the moving parts and transmission threads of the self-adjusting mechanism. Over time, these impurities will accelerate the wear of parts, increase the resistance to movement, and eventually cause jamming. Existing structures mostly use only simple sealing rings for protection and lack active cleaning capabilities.

[0008] Fourth, the preload is not adjustable, which can easily lead to dragging and jamming. The return preload of existing self-adjusting mechanisms is mostly a factory fixed value. As the wear of the brake friction pads increases, the compression of the return spring changes, and the preload will deviate from the optimal range. Insufficient preload will result in incomplete return and brake dragging, while excessive preload will aggravate the wear of the transmission pair, both of which will increase the probability of jamming failure.

[0009] Therefore, a self-adjusting anti-jamming device for commercial vehicle air disc brakes is needed to solve the above problems. Summary of the Invention

[0010] The purpose of this invention is to provide a self-adjusting anti-jamming device for air disc brakes in commercial vehicles to solve the problems mentioned in the background art.

[0011] To achieve the above objectives, the present invention provides the following technical solution:

[0012] A self-adjusting clearance and anti-jamming device for a commercial vehicle air disc brake includes a brake caliper body, a brake push rod, a self-adjusting transmission unit, a redundant clearance adjustment unit, a self-cleaning protection unit, and an adaptive pretensioning unit; the brake push rod is slidably inserted into the brake caliper body, and the self-adjusting transmission unit, the redundant clearance adjustment unit, the self-cleaning protection unit, and the adaptive pretensioning unit are all integrated into the mounting cavity of the brake caliper body.

[0013] The output end of the self-adjusting transmission unit is connected to the input end of the redundant gap adjustment unit. The output end of the redundant gap adjustment unit is driven by the brake push rod. The self-cleaning protection unit is located at the port of the mounting cavity and sleeved on the outside of the brake push rod. The adaptive pre-tightening unit is sleeved on the outside of the brake push rod and its two ends abut against the limiting structure of the brake caliper and the brake push rod, respectively.

[0014] This device constructs an overall architecture that includes a three-level anti-jamming structure. Through the coordinated operation of the self-adjusting transmission unit, redundant clearance adjustment unit, self-cleaning protection unit, and adaptive pre-tightening unit, the anti-jamming capability is improved layer by layer from overload protection and functional redundancy to environmental adaptation. It covers three typical jamming causes and constructs a relatively complete anti-jamming technology system, thereby improving the working reliability of the self-adjusting mechanism under complex working conditions.

[0015] Furthermore, the self-adjusting transmission unit includes a self-adjusting shaft, a one-way clutch assembly, a multi-stage friction unloading assembly, and a preload adjustment component; the self-adjusting shaft is rotatably connected to the brake caliper body, the one-way clutch assembly is sleeved on the input end of the self-adjusting shaft, the multi-stage friction unloading assembly is disposed on the output side of the one-way clutch assembly, and the preload adjustment component is threadedly connected to the brake caliper body, with its end abutting against the end face of the multi-stage friction unloading assembly.

[0016] The self-adjusting transmission unit ensures the unidirectionality of the gap adjustment transmission through a one-way clutch assembly, avoiding reverse misadjustment; in conjunction with a multi-stage friction unloading assembly and preload adjustment components, the unloading torque threshold can be flexibly adjusted to adapt to the braking torque requirements of commercial vehicles of different tonnages, improving the device's adaptability to operating conditions and overload protection capabilities.

[0017] Furthermore, the multi-stage friction unloading assembly includes a first friction plate, an intermediate transmission ring, and a second friction plate; the first friction plate is circumferentially fixed to the output end of the one-way clutch assembly, the second friction plate is circumferentially fixed to the self-adjusting shaft, the intermediate transmission ring is sandwiched between the first friction plate and the second friction plate, and the end of the pre-tightening adjustment member abuts against the outer end face of the second friction plate.

[0018] The multi-stage unloading structure with dual friction surfaces achieves two-stage friction unloading through an intermediate transmission ring. Compared with a single-stage friction structure, the unloading process is smoother, which can reduce the damage of impact load to the transmission pair, while dispersing friction loss and improving the service life of the unloading components. Moreover, the structure is simple and compact, making it easy to assemble and maintain.

[0019] Furthermore, the redundant adjustment unit includes a main adjustment transmission pair, a secondary adjustment transmission pair, and a switching trigger assembly; the main adjustment transmission pair is connected between the output end of the self-adjusting shaft and the brake push rod, and the secondary adjustment transmission pair is detachably connected between the self-adjusting shaft and the brake push rod through the switching trigger assembly.

[0020] Two adjustment transmission paths are set up: the main path works under normal operating conditions and the secondary path is in standby mode. When the main path gets stuck, the secondary path automatically engages, realizing redundancy backup of the adjustment function, avoiding the complete loss of self-adjustment function due to single path failure, and improving the safety redundancy of the braking system.

[0021] Furthermore, the switching trigger assembly includes a switching slide, a switching spring, and a limiting retaining ring; the switching slide is slidably sleeved on the self-adjusting shaft, the driving component of the secondary clearance adjustment transmission pair is disposed on the switching slide, the switching spring is sleeved on the self-adjusting shaft and its two ends respectively abut against the switching slide and the brake caliper body, and the limiting retaining ring is engaged with the self-adjusting shaft to limit the initial position of the switching slide.

[0022] Automatic switching between primary and secondary paths is achieved through a spring-driven switching trigger assembly, eliminating the need for additional electronic control components and ensuring high reliability due to its purely mechanical structure. The switching threshold can be adjusted by the parameters and pre-compression of the switching spring to adapt to different resistance triggering requirements, resulting in a timely switching response.

[0023] Furthermore, the self-cleaning protection unit includes a sealing end cap, a purge air passage, and a dustproof lip ring; the sealing end cap is fixed to the mounting cavity port of the brake caliper body, the purge air passage is opened in the mating area of ​​the sealing end cap and the brake push rod, and the dustproof lip ring is embedded in the inner ring of the sealing end cap and fits against the outer surface of the brake push rod.

[0024] Passive sealing protection is achieved through sealed end caps and dustproof lip rings, while active cleaning is achieved in conjunction with the purging air passage. This creates a dual protection system of passive isolation and active purging, effectively reducing the probability of external impurities entering the transmission cavity, lowering the risk of impurity jamming, and improving environmental adaptability.

[0025] Furthermore, the air inlet of the purge air passage is connected to the air pressure chamber of the brake caliper, and the air outlet faces the mating gap between the brake push rod and the mounting cavity, which is used to guide the gas in the air pressure chamber to form a purge airflow when the brake push rod moves axially.

[0026] Using the air in the brake's own air chamber as the purging air source, there is no need for additional air pumps or other devices. The purging action is automatically triggered by the reciprocating motion of the brake push rod. The structure is simple and synchronized with the braking process. Each braking action completes a cleaning, continuously maintaining the cleanliness of the transmission surface.

[0027] Furthermore, the adaptive preload unit includes a return spring, a spring seat, and a wear compensation component; the spring seat is slidably sleeved on the brake push rod, the return spring is sleeved on the outside of the brake push rod with its two ends abutting against the spring seat and the brake caliper body respectively, and the wear compensation component is disposed between the spring seat and the limiting step of the brake push rod.

[0028] By cooperating with the wear compensation component, return spring, and spring seat, the compression of the return spring can be automatically adjusted according to the wear of the brake friction pads, maintaining the preload within a reasonable range, ensuring reliable return of the brake push rod, avoiding dragging and jamming, and reducing unnecessary wear of the transmission pair.

[0029] Furthermore, the wear compensation component adopts an elastic energy storage structure, which deforms synchronously with the axial compensation displacement of the brake push rod, and is used to adjust the compression of the return spring.

[0030] It adopts an elastic energy storage wear compensation component, which can deform synchronously with the compensation displacement of the brake push rod without additional adjustment. It automatically compensates for the change in spring compression caused by wear, and the preload adjustment process is smooth and continuous, ensuring long-term stable return performance.

[0031] Furthermore, both the main and secondary adjustable clearance transmission pairs include a lead screw and nut transmission structure. The driven parts of both are fixed relative to the brake push rod, and the driving parts are circumferentially driven by the self-adjusting shaft through a bevel gear reversing pair.

[0032] Both the main and auxiliary clearance adjustment transmission pairs adopt a transmission structure of lead screw nut + bevel gear reversal, which ensures smooth transmission and high clearance adjustment accuracy. The transmission forms of the two are consistent, which facilitates processing, assembly, interchangeability and maintenance. It can ensure that the clearance adjustment accuracy is basically consistent with that of the main path after the auxiliary path is connected, and reduce the clearance adjustment deviation.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] This invention enhances overload protection and reduces the probability of transmission jamming: It replaces the existing single conical spring buffer structure with a multi-stage friction unloading component in the self-adjusting transmission unit. The structure employs a two-stage friction pair with a pre-tightening adjustment component, enabling graded and gradual unloading. When braking impact causes the transmission torque to exceed a preset threshold, the first friction plate and the intermediate transmission ring, and the intermediate transmission ring and the second friction plate, sequentially slide relative to each other, gradually releasing the overload torque and avoiding stress concentration and tooth seizure caused by rigid meshing of the transmission pairs. Simultaneously, the axial clamping force of the friction pair can be adjusted by turning the pre-tightening adjustment component, allowing for flexible adjustment of the unloading torque threshold. This adapts to commercial vehicle braking systems of different tonnages and operating conditions, broadening the device's applicability.

[0035] This invention achieves redundancy in the gap adjustment function, reducing the risk of failure: Redundant gap adjustment units are set up to construct a dual-path gap adjustment transmission structure; under normal operating conditions, the main gap adjustment transmission pair undertakes all gap compensation work, while the secondary gap adjustment transmission pair is in a standby, disconnected state; when the main gap adjustment transmission pair becomes stuck due to wear, impurities, etc., and the transmission resistance rises to the switching threshold, the switching spring of the switching trigger component is compressed, driving the switching slide to move axially, causing the secondary gap adjustment transmission pair to engage and continue completing the gap compensation action; automatic redundant switching is achieved through a purely mechanical structure, eliminating the need for an additional electronic control system, maintaining normal operation of the self-adjustment function when the main path fails, preventing the braking gap from continuously increasing, and improving the safety and reliability of the braking system.

[0036] This invention constructs a dual protection system to reduce the risk of impurity jamming: the self-cleaning protection unit adopts a dual protection structure combining passive sealing and active purging; the dustproof lip ring and the sealing end constitute the first passive protection, blocking most of the external dust and mud from entering the installation cavity; the purging air passage connects the brake air pressure chamber and the clearance between the push rod and the brake push rod. When the brake push rod extends, the compressed air in the air pressure chamber flows to the clearance through the purging air passage, forming an outward purging airflow that blows out the small amount of impurities that have entered the clearance, achieving active cleaning during each braking process; through dual protection, the probability of impurities entering the transmission pair and threaded mating surfaces is effectively reduced, reducing component wear and lowering the incidence of motion jamming failures caused by impurity accumulation.

[0037] This invention achieves adaptive adjustment of preload, reducing drag and wear-induced jamming: The adaptive preload unit, through the cooperation of a wear compensation component and a return spring, can dynamically adjust the return preload according to the wear of the brake friction pads; when the brake friction pads wear, and the brake push rod undergoes compensating displacement towards the brake disc, the wear compensation component undergoes elastic deformation synchronously with the push rod, maintaining the compression of the return spring within a reasonable range, avoiding insufficient return and brake drag caused by spring elongation and preload reduction due to wear, while also preventing excessive preload from aggravating wear on the transmission pair; by adaptively adjusting the return preload to an optimal range, it ensures reliable return of the brake push rod while reducing unnecessary wear, thus helping to reduce the probability of drag and wear-induced jamming from the root.

[0038] To more clearly illustrate the structural features and effects of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0039] Figure 1 This is a block diagram of the overall unit-level architecture of the present invention;

[0040] Figure 2 This is a detailed structural block diagram of all parts of the present invention.

[0041] In the diagram: 1. Brake caliper body; 2. Brake push rod; 3. Self-adjusting transmission unit; 31. Self-adjusting shaft; 32. One-way clutch assembly; 33. Multi-stage friction unloading assembly; 331. First friction plate; 332. Intermediate transmission ring; 333. Second friction plate; 34. Preload adjustment component; 4. Redundant clearance adjustment unit; 41. Main clearance adjustment transmission pair; 42. Secondary clearance adjustment transmission pair; 43. Switching trigger assembly; 431. Switching slide; 432. Switching spring; 433. Limiting retaining ring; 5. Self-cleaning protection unit; 51. Sealing end cover; 52. Purge air passage; 53. Dustproof lip ring; 6. Adaptive preload unit; 61. Return spring; 62. Spring seat; 63. Wear compensation component. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0043] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0044] Example 1

[0045] like Figure 1-2As shown, this embodiment of the invention provides a self-adjusting clearance anti-jamming device for a commercial vehicle air disc brake, including a brake caliper body 1, a brake push rod 2, a self-adjusting transmission unit 3, a redundant clearance adjustment unit 4, a self-cleaning protection unit 5, and an adaptive preload unit 6. The brake caliper body 1 has an internal mounting cavity. The brake push rod 2 slides axially through the mounting cavity, with its outer end abutting against the brake friction pad backing plate and its inner end connected to the redundant clearance adjustment unit 4. The self-adjusting transmission unit 3, the redundant clearance adjustment unit 4, and the adaptive preload unit 6 are all housed within the mounting cavity. The self-cleaning protection unit 5 is installed at the outer port of the mounting cavity and sleeved on the outside of the brake push rod 2.

[0046] The self-adjusting transmission unit 3 includes a self-adjusting shaft 31, a one-way clutch assembly 32, a multi-stage friction unloading assembly 33, and a preload adjustment component 34. The self-adjusting shaft 31 is rotatably supported in the mounting cavity of the brake caliper body 1 by bearings, and its axis is perpendicular to the axis of the brake push rod 2. The one-way clutch assembly 32 adopts a ratchet and pawl type one-way clutch, with its inner ring connected to the shift fork shaft driven by the brake air chamber, and its outer ring serving as the output end connected to the multi-stage friction unloading assembly 33. The multi-stage friction unloading assembly 33 includes a first friction plate 331, an intermediate transmission ring 332, and a second friction plate 333. The first friction plate 331 is circumferentially fixed to the outer ring of the one-way clutch assembly 32 by a spline, and the second friction plate 333 is circumferentially fixed to the input end of the self-adjusting shaft 31 by a spline. The intermediate transmission ring 332 is an annular structure, sandwiched between the first friction plate 331 and the second friction plate 333, with its two end faces respectively in contact with the friction surfaces of the two friction plates. The preload adjustment component 34 is an adjustment plug that is threadedly connected to the threaded hole on the side wall of the brake caliper body 1. Its inner end abuts against the outer end face of the second friction plate 333. The axial clamping force of the friction pair can be adjusted by screwing the preload adjustment component 34.

[0047] The redundant clearance adjustment unit 4 includes a main clearance adjustment transmission pair 41, a secondary clearance adjustment transmission pair 42, and a switching trigger assembly 43. Both the main clearance adjustment transmission pair 41 and the secondary clearance adjustment transmission pair 42 adopt a transmission structure of "bevel gear reversing pair + lead screw nut". The driven nuts of both are fixed relative to the brake push rod 2, and the driving bevel gears are circumferentially driven by the self-adjusting rotating shaft 31.

[0048] The main driving bevel gear of the main adjusting transmission pair 41 is fixed to the output end of the self-adjusting shaft 31. The main driven bevel gear is coaxially fixed with the main lead screw, and the axis of the main lead screw is parallel to the axis of the brake push rod 2. The main nut is fixed to the inner end of the brake push rod 2. The main lead screw and the main nut are threadedly engaged, forming the main adjusting path. The tail of the main lead screw axially abuts against the switching slide 431, which can convert the transmission resistance into axial thrust. The secondary driving bevel gear of the secondary adjusting transmission pair 42 is fixed on the switching slide 431. The secondary driven bevel gear is coaxially fixed with the secondary lead screw. The secondary nut is fixed to the inner end side wall of the brake push rod 2. The secondary lead screw and the secondary nut can be separably engaged.

[0049] The switching trigger assembly 43 includes a switching slide 431, a switching spring 432, and a limiting retaining ring 433. The switching slide 431 is slidably mounted on the self-adjusting shaft 31 via a spline and can slide axially along the self-adjusting shaft 31. The switching spring 432 is a cylindrical compression spring, mounted on the self-adjusting shaft 31, with one end abutting against the end face of the switching slide 431 and the other end abutting against the inner wall of the brake caliper body 1. The limiting retaining ring 433 is engaged in the annular groove of the self-adjusting shaft 31 and is located on the other side of the switching slide 431, used to limit the initial position of the switching slide 431. In the initial state, the preload of the switching spring 432 pushes the switching slide 431 against the limiting retaining ring 433. At this time, the secondary driving bevel gear and the secondary driven bevel gear of the secondary clearance transmission pair 42 are in a separated state, and the secondary path is disconnected.

[0050] The self-cleaning protection unit 5 includes a sealing end cap 51, a purge air passage 52, and a dustproof lip ring 53. The sealing end cap 51 is fixed to the outer port of the mounting cavity of the brake caliper body 1 by bolts, and has a through hole in the center for the brake push rod 2 to pass through. The dustproof lip ring 53 is embedded in the annular groove of the inner ring of the sealing end cap 51, with the lip facing the outside of the cavity, and is tightly fitted to the outer circumferential surface of the brake push rod 2 to form an outer seal. The purge air passage 52 is opened in the mating area inside the sealing end cap 51. The air inlet end is connected to the air pressure chamber of the brake caliper body 1 through a connecting hole, and the air outlet end is located on the inner side of the inner ring of the sealing end cap 51, facing the mating gap between the brake push rod 2 and the mounting cavity. The air outlet direction is outward along the axial direction of the brake push rod 2, which can guide the gas in the air pressure chamber to form a purge airflow when the brake push rod 2 moves axially.

[0051] The adaptive preload unit 6 includes a return spring 61, a spring seat 62, and a wear compensation component 63. The spring seat 62 is an annular structure, slidably sleeved on the outside of the brake push rod 2, located inside the mounting cavity. The return spring 61 is a cylindrical compression spring, sleeved on the outside of the brake push rod 2, with one end abutting against the outer end face of the spring seat 62 facing the inner wall of the caliper, and the other end abutting against the inner wall step of the mounting cavity. The wear compensation component 63 is a disc spring assembly, an elastic energy storage structure, sandwiched between the inner end face of the spring seat 62 and the limiting step on the outer wall of the brake push rod 2. It deforms synchronously with the axial compensation displacement of the brake push rod 2, adjusting the compression of the return spring 61. When the brake push rod 2 moves towards the brake disc to compensate for wear, the limiting step moves synchronously, pushing the spring seat 62 to move via the wear compensation component 63, adjusting the compression of the return spring 61.

[0052] In this embodiment, the device operates as follows:

[0053] During braking, the brake chamber pushes the shift fork shaft to swing, causing the one-way clutch assembly 32 to rotate. The power is transmitted to the self-adjusting shaft 31 via the multi-stage friction unloading assembly 33. The self-adjusting shaft 31 drives the main and driven bevel gears to rotate synchronously. After the main and driven bevel gears reverse direction, the main screw rotates, and through the screw nut transmission, the brake push rod 2 extends axially, pushing the brake friction pads against the brake disc to achieve braking. When there is excessive wear clearance between the brake friction pads and the brake disc, the rotation angle of the self-adjusting shaft 31 exceeds the preset travel, causing the brake push rod 2 to generate additional axial displacement, thus completing clearance compensation.

[0054] When the braking impact is too large and the transmission torque exceeds the unloading threshold of the multi-stage friction unloading assembly 33, relative sliding occurs sequentially between the first friction plate 331 and the intermediate transmission ring 332, and between the intermediate transmission ring 332 and the second friction plate 333, gradually releasing the overload torque and preventing damage to the tooth surface or jamming of the one-way clutch assembly 32 and the lead screw nut pair due to rigid overload. The unloading torque threshold can be adjusted by the preload adjustment component 34. Screwing the preload adjustment component 34 in increases the clamping force of the friction pair and raises the unloading threshold; screwing it out lowers the unloading threshold.

[0055] When the main adjustment transmission pair 41 becomes stuck due to impurities, thread wear, or other reasons, and the transmission resistance continues to increase, the rotational resistance will generate an axial counterforce on the main lead screw based on the force characteristics of the helical inclined surface of the lead screw nut. When the axial thrust exceeds the preload of the switching spring 432, the main lead screw slides axially, pushing the switching slide 431 to compress the switching spring 432 and move axially, so that the secondary driving bevel gear meshes with the secondary driven bevel gear, and the secondary adjustment path is connected. The power continues to drive the brake push rod 2 to complete the clearance compensation action through the secondary bevel gear reversing pair and the secondary lead screw nut pair, ensuring that the self-adjustment function is not interrupted.

[0056] After the brake is released, the return spring 61 pushes the spring seat 62 and the brake push rod 2 back to their original positions, causing the brake friction pads to disengage from the brake disc. As the wear of the brake friction pads increases, the initial position of the brake push rod 2 gradually shifts towards the brake disc. At this time, the disc spring assembly of the wear compensation component 63 will undergo corresponding deformation with the displacement of the limit step, compensating for the change in the compression of the return spring 61, keeping the preload of the return spring 61 within the design range, ensuring smooth return and reducing the risk of dragging.

[0057] During the reciprocating motion of the brake push rod 2 extending and retracting, the compressed air in the brake air chamber flows through the purge air passage 52 to the mating gap of the brake push rod 2, forming an outward purge airflow that blows out dust, mud, water and other impurities in the gap. Combined with the sealing barrier of the dustproof lip ring 53, this reduces the probability of impurities entering the mounting cavity and maintains the cleanliness of the transmission pair.

[0058] This embodiment includes two typical use cases:

[0059] Scenario 1: Conventional braking conditions on main highways. Commercial vehicles travel on paved roads with minimal dust, resulting in smooth braking. In this scenario, the self-adjusting mechanism completes conventional clearance compensation via the main clearance path. The multi-stage friction unloading components are in synchronous transmission. The self-cleaning protection unit performs a light cleaning with each braking action, maintaining the cleanliness of the transmission surfaces. The adaptive preload unit gradually adjusts the preload as the brake pads wear slowly, ensuring stable return performance. Under these conditions, the device operates smoothly, all units are under low load, and the service life is extended.

[0060] Scenario 2: Unpaved road conditions at mining construction sites. Commercial vehicles travel in harsh environments with high levels of dust and mud, experiencing frequent braking and significant impacts. In this situation, the multi-stage friction unloading components frequently intervene to buffer braking impacts and reduce the probability of transmission pair overload and jamming. The self-cleaning protection unit's blowing action is executed at high frequency with braking, continuously cleaning impurities entering the gaps and reducing impurity accumulation and jamming. If the main adjustment path experiences temporary jamming due to impurities, the secondary adjustment path automatically engages to ensure normal adjustment function. In this scenario, the triple anti-jamming structure works synergistically to effectively address the jamming risk under harsh working conditions.

[0061] This embodiment includes three core calculation formulas, each corresponding to a core parameter of the three technical points:

[0062] Overload unloading torque calculation formula:

[0063]

[0064] In the formula:

[0065] The unloading threshold torque of the multi-stage friction unloading assembly, in N·m;

[0066] The coefficient of friction between the friction plate and the intermediate transmission ring is determined by the material and surface treatment process of the friction pair. In this embodiment, paper-based friction material is used. The value range is 0.3 to 0.45;

[0067] The preload adjustment component applies axial preload to the friction pair, measured in N. This preload is controlled by adjusting the screw-in depth of the preload adjustment component. For every 1mm increase in screw-in depth, Increased by approximately 150N;

[0068] The effective radius of the friction surface, in meters, is the average of the outer and inner radii of the friction surface, and is determined by the structural design.

[0069] Constraints: ,in This is the transmission torque during normal clearance adjustment. This refers to the yield torque of the transmission pair components.

[0070] Control logic: When transmission torque At this time, there is no relative sliding between the friction pairs, and torque is transmitted synchronously; when When this occurs, the friction pair produces relative sliding, releasing the overload torque and protecting the downstream transmission components.

[0071] This formula is used to quantify the design and adjustment of the unloading threshold, ensuring that the unloading action is triggered accurately, without affecting normal clearance adjustment, and effectively preventing overload jamming.

[0072] Adaptive preload calculation formula:

[0073] The return spring and wear compensation component are arranged in series along the axial direction of the brake push rod, and the force they bear is always equal. The total compression changes dynamically with the amount of wear. The derivation formula is as follows:

[0074]

[0075] In the formula:

[0076] The cumulative wear of the brake friction pads is: The return preload force at that time, in N;

[0077] : Initial return preload force, in N, is the set value at the time of factory assembly;

[0078] : Stiffness coefficient of the return spring, in N / mm;

[0079] The stiffness coefficient of the wear compensation component is expressed in N / mm. In this embodiment, the stiffness of the disc spring assembly is much smaller than that of the return spring.

[0080] The cumulative wear of the brake friction pads, in mm, is calculated from the cumulative compensation displacement of the brake push rod.

[0081] Constraints: ,in To ensure the minimum preload for reliable return, The maximum permissible preload force to avoid exacerbating wear on the transmission pair.

[0082] Control logic: When the brake friction pads experience wear... At that time, the brake push rod moves towards the brake disc. The distance, the total compression of the return spring and wear compensation component decreases. Since the stiffness of the wear compensation component is much smaller than that of the return spring, the reduction in compression is mainly released by the wear compensation component, and the change in the compression of the return spring is very small. Therefore, the fluctuation of the return preload is greatly weakened and kept within the allowable range.

[0083] This formula is used to guide the parameter matching of wear compensation components and return springs, so as to achieve adaptive adjustment of preload and avoid jamming caused by the preload deviating from the optimal range.

[0084] Formula for calculating the redundancy path switching resistance threshold:

[0085]

[0086] In the formula:

[0087] : Resistance threshold for switching between primary and secondary control paths, in N;

[0088] : The stiffness coefficient of the switching spring, in N / mm;

[0089] The initial pre-compression of the switching spring, in mm, can be adjusted by changing the installation position of the limit ring or by adding or removing shims.

[0090] Constraints: ,in The motion resistance when the main clearance path is working normally. The minimum resistance when the main path is blocked.

[0091] Control logic: When the motion resistance of the main adjustment path is less than When the main path is stuck, the preload of the switching spring maintains the switching slide in the initial position, and the secondary path separates; when the main path is stuck, the resistance exceeds the limit. When the switching spring is compressed, the slide moves to engage the secondary path.

[0092] This formula is used to precisely set the switching threshold, ensuring that the secondary path does not intervene under normal operating conditions, and that the secondary path reliably switches in when the primary path is stuck.

[0093] In this embodiment, the triple anti-jamming technology achieves a progressive and synergistic effect: the first layer, a multi-stage friction unloading structure, reduces transmission pair jamming caused by overload at the source, serving as the basic anti-jamming defense; the second layer, a dual-path redundancy structure, provides functional backup in the event of single-path jamming, ensuring uninterrupted self-adjustment function, forming the second functional defense; the third layer, a self-cleaning and adaptive pre-tightening structure, reduces jamming-inducing factors and lowers the probability of jamming from the perspective of environmental adaptation and state maintenance, forming the long-term third defense. These three technologies target three typical fault types: overload jamming, failure jamming, and environment-induced jamming, providing layered protection and complementing each other. Compared to a single anti-jamming structure, this significantly reduces the overall jamming failure rate and improves the reliability of the device under all operating conditions.

[0094] Example 2

[0095] The difference between this embodiment and Embodiment 1 is that the multi-stage friction unloading assembly 33 adopts a three-stage friction surface structure. A second intermediate transmission ring and a third friction plate are added between the intermediate transmission ring 332 and the second friction plate 333 to form a three-stage friction pair series unloading structure. The end of the preload adjusting member 34 abuts against the end face of the outermost friction plate through a thrust bearing to reduce frictional resistance during the adjustment process.

[0096] In this embodiment, the three-stage friction pair enables smoother, graded unloading. Under overload, the three friction surfaces slip sequentially, resulting in smaller torque fluctuations during unloading and lower impact on the transmission system. This design is suitable for heavy-duty mining vehicles with greater braking impact. The three-stage friction pair disperses friction losses, reducing wear on each friction surface and extending the service life of the unloading assembly while minimizing maintenance frequency. Simultaneously, the thrust bearing design facilitates smoother preload adjustment, allowing for easier adjustment of the unloading threshold during on-site maintenance. This avoids uneven wear caused by the friction plates rotating synchronously with the screw plug during adjustment, thus improving overall overload protection performance and maintenance convenience under heavy-load conditions.

[0097] Example 3

[0098] The difference between this embodiment and embodiment 1 is that the secondary adjustment transmission pair 42 adopts a gear and rack transmission structure. The rack is axially arranged on the side wall of the brake push rod 2. The secondary gear is mounted on the switching slide 431 through a rotating shaft. The secondary gear and the rack can be separably meshed. The axis of the secondary gear is parallel to the self-adjusting rotating shaft 31. When the switching slide 431 moves axially along the self-adjusting rotating shaft 31, it drives the secondary gear to approach and mesh with the rack, realizing the access of the secondary path.

[0099] In this embodiment, the rack and pinion transmission pair has higher transmission efficiency and stronger load-bearing capacity. It provides more reliable clearance adjustment power when the main path jams, reducing the probability of secondary jamming due to insufficient load-bearing capacity of the secondary path. Simultaneously, the meshing clearance of the rack and pinion is easier to control, resulting in less impact during engagement and a smoother switching process, reducing damage to the gear teeth from transmission shocks during switching. This structure is suitable for large-tonnage commercial vehicle brakes with high clearance adjustment force requirements, ensuring stable clearance compensation after the secondary path is engaged, and improving the operational reliability and clearance adjustment smoothness of the redundant path.

[0100] Example 4

[0101] The difference between this embodiment and Embodiment 1 is that the self-cleaning protection unit 5 is equipped with a labyrinth seal structure. Multiple annular labyrinth teeth are provided at the mating surface of the sealing end cap 51 and the brake push rod 2. The labyrinth teeth are located inside the dustproof lip ring 53, forming a tortuous sealing channel. The air outlet of the purge air passage 52 is located in the middle cavity of the labyrinth seal.

[0102] In this embodiment, the labyrinth seal constitutes a second layer of passive protection, forming a double sealing barrier in conjunction with the dustproof lip ring. This more effectively prevents mud, water, and large dust particles from entering the cavity, extending the path length for impurities to enter and reducing the probability of penetration. The purging airflow creates turbulence within the labyrinth cavity, more thoroughly removing impurities that have entered the labyrinth, improving cleaning efficiency, and reducing the possibility of impurities accumulating and hardening at the seal. This structure significantly enhances protection under harsh muddy and water conditions, making it suitable for commercial vehicle brakes in various muddy and watery environments such as construction sites and mining areas. It further reduces the risk of impurities getting stuck and extends the service life of the seals.

[0103] Example 5

[0104] The difference between this embodiment and Embodiment 1 is that the wear compensation component 63 uses a wave spring assembly with nonlinear stiffness, whose stiffness gradually increases with increasing compression. The return spring 61 uses a variable pitch cylindrical spring, whose stiffness decreases slightly with increasing elongation. The combination of the two achieves a wider range of preload stability.

[0105] In this embodiment, by matching a nonlinear spring, the fluctuation range of the return preload is smaller throughout the wear range of the brake friction pads' entire life cycle, consistently remaining near an optimal range. Compared to a linear spring structure, the nonlinear structure can reduce the preload fluctuation range by more than 40%, further reducing the probability of dragging, jamming, and wear jamming caused by abnormal preload, and extending the brake's maintenance cycle. Simultaneously, the wave spring has a smaller axial dimension, saving installation space and adapting to a more compact brake cavity structure, achieving better preload adjustment within a limited installation space and improving operational reliability throughout the entire life cycle.

[0106] Example 6

[0107] The difference between this embodiment and Embodiment 1 is that a wear detection unit is added to the mounting cavity of the brake caliper 1, including a displacement sensor and a signal output terminal. The displacement sensor is used to detect the cumulative compensation displacement of the brake push rod 2 and calculate the wear amount of the brake friction pads. The signal from the displacement sensor can be transmitted to the vehicle's instrument panel to indicate the wear status of the brake friction pads to the driver.

[0108] In this embodiment, the wear detection unit can monitor the wear of the brake pads and the working status of the self-adjusting mechanism in real time. When the compensation amount of the self-adjusting mechanism is abnormal or a jamming fault occurs, it can issue an early warning in time, allowing the driver to arrange maintenance in advance and reducing the probability of braking safety problems caused by undetected jamming faults. This structure improves the intelligence level of the brake and is suitable for the braking system of high-end commercial vehicles. Combined with the triple anti-jamming structure, it achieves a combination of active warning and passive protection, further improving the safety and maintainability of the braking system and reducing the probability of sudden failures.

[0109] Example 7

[0110] The difference between this embodiment and embodiment 1 is that the self-adjusting gap anti-jamming device is applied to a double push rod pneumatic disc brake, which includes two sets of symmetrically arranged brake push rods 2 and redundant gap adjustment units 4. The self-adjusting transmission unit 3 drives the two sets of redundant gap adjustment units 4 simultaneously through a synchronous gear mechanism to ensure that the gap compensation of the brake push rods 2 on both sides is synchronized.

[0111] In this embodiment, both sides of the dual pushrod structure are equipped with independent redundant clearance adjustment and anti-jamming structures. A jamming failure on one side does not affect the operation of the other side. Simultaneously, the synchronous gear mechanism ensures consistent clearance adjustment on both sides, reducing uneven wear of the brake pads. This structure is suitable for heavy-duty commercial vehicle brakes with large-size brake discs. While ensuring synchronous clearance adjustment of the dual pushrods, it comprehensively improves the anti-jamming capability of both pushrods, resulting in higher braking stability and reliability. It can meet the high braking force requirements of heavy vehicles and reduce the risk of brake deviation caused by unilateral jamming.

[0112] Example 8

[0113] The difference between this embodiment and Embodiment 1 is that the friction plates of the multi-stage friction unloading assembly 33 are made of ceramic matrix composite material, and the friction surface of the intermediate transmission ring is coated with a wear-resistant coating. Meanwhile, the threaded surface of the lead screw and nut transmission pair is phosphated to improve wear resistance and rust prevention.

[0114] In this embodiment, the ceramic-based friction material exhibits a more stable coefficient of friction and less performance degradation at high temperatures. It can adapt to high-temperature operating conditions caused by frequent braking, reducing the probability of unloading threshold deviation due to a decrease in the coefficient of friction at high temperatures, and ensuring stable overload protection performance under high-temperature environments. The wear-resistant coating and phosphating treatment enhance the wear resistance and corrosion resistance of the transmission pair, reducing wear and rust jamming and extending the service life of the transmission pair. This structure is suitable for commercial vehicles operating in mountainous areas with frequent braking, maintaining stable anti-jamming performance under high-temperature and high-load conditions, and reducing the jamming failure rate under long-term high-load operation.

[0115] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A self-adjusting clearance anti-jamming device for a commercial vehicle air disc brake, characterized in that, It includes a brake caliper body (1), a brake push rod (2), a self-adjusting transmission unit (3), a redundant gap adjustment unit (4), a self-cleaning protection unit (5), and an adaptive pretensioning unit (6); the brake push rod (2) is slidably inserted into the brake caliper body (1), and the self-adjusting transmission unit (3), the redundant gap adjustment unit (4), the self-cleaning protection unit (5), and the adaptive pretensioning unit (6) are all integrated into the mounting cavity of the brake caliper body (1); The output end of the self-adjusting transmission unit (3) is connected to the input end of the redundant gap adjustment unit (4). The output end of the redundant gap adjustment unit (4) is connected to the brake push rod (2). The self-cleaning protection unit (5) is located at the port of the mounting cavity and sleeved on the outside of the brake push rod (2). The adaptive pre-tightening unit (6) is sleeved on the outside of the brake push rod (2) and its two ends abut against the limiting structure of the brake caliper (1) and the brake push rod (2) respectively.

2. The self-adjusting clearance anti-jamming device for a commercial vehicle air disc brake according to claim 1, characterized in that, The self-adjusting transmission unit (3) includes a self-adjusting shaft (31), a one-way clutch assembly (32), a multi-stage friction unloading assembly (33), and a pre-tightening adjustment component (34). The self-adjusting shaft (31) is rotatably connected to the brake caliper body (1). The one-way clutch assembly (32) is sleeved on the input end of the self-adjusting shaft (31). The multi-stage friction unloading assembly (33) is located on the output side of the one-way clutch assembly (32). The pre-tightening adjustment component (34) is threadedly connected to the brake caliper body (1), and its end abuts against the end face of the multi-stage friction unloading assembly (33).

3. The self-adjusting clearance anti-jamming device for a commercial vehicle air disc brake according to claim 2, characterized in that, The multi-stage friction unloading assembly (33) includes a first friction plate (331), an intermediate transmission ring (332), and a second friction plate (333). The first friction plate (331) is circumferentially fixed to the output end of the one-way clutch assembly (32), and the second friction plate (333) is circumferentially fixed to the self-adjusting shaft (31). The intermediate transmission ring (332) is sandwiched between the first friction plate (331) and the second friction plate (333). The end of the pre-tightening adjustment member (34) abuts against the outer end face of the second friction plate (333).

4. The self-adjusting clearance anti-jamming device for a commercial vehicle air disc brake according to claim 2, characterized in that, The redundant gap adjustment unit (4) includes a main gap adjustment transmission pair (41), a secondary gap adjustment transmission pair (42), and a switching trigger assembly (43). The main gap adjustment transmission pair (41) is connected between the output end of the self-adjusting shaft (31) and the brake push rod (2). The secondary gap adjustment transmission pair (42) is detachably connected between the self-adjusting shaft (31) and the brake push rod (2) through the switching trigger assembly (43).

5. A self-adjusting anti-jamming device for a commercial vehicle air disc brake according to claim 4, characterized in that, The switching trigger assembly (43) includes a switching slide (431), a switching spring (432), and a limiting retaining ring (433). The switching slide (431) is slidably sleeved on the self-adjusting shaft (31). The driving component of the secondary adjustment transmission pair (42) is set on the switching slide (431). The switching spring (432) is sleeved on the self-adjusting shaft (31) and its two ends abut against the switching slide (431) and the brake caliper (1) respectively. The limiting retaining ring (433) is engaged with the self-adjusting shaft (31) to limit the initial position of the switching slide (431).

6. The self-adjusting clearance anti-jamming device for a commercial vehicle air disc brake according to claim 1, characterized in that, The self-cleaning protection unit (5) includes a sealing end cap (51), a purge air passage (52), and a dustproof lip ring (53); the sealing end cap (51) is fixed to the mounting cavity port of the brake caliper body (1), the purge air passage (52) is opened in the mating area of ​​the sealing end cap (51) and the brake push rod (2), and the dustproof lip ring (53) is embedded in the inner ring of the sealing end cap (51) and fits against the outer surface of the brake push rod (2).

7. A self-adjusting anti-jamming device for a commercial vehicle air disc brake according to claim 6, characterized in that, The air inlet of the purge air passage (52) is connected to the air pressure chamber of the brake caliper (1), and the air outlet is directed toward the fit gap between the brake push rod (2) and the mounting cavity, so as to guide the gas in the air pressure chamber to form a purge airflow when the brake push rod (2) moves axially.

8. The self-adjusting clearance anti-jamming device for a commercial vehicle air disc brake according to claim 1, characterized in that, The adaptive preload unit (6) includes a return spring (61), a spring seat (62), and a wear compensation component (63); the spring seat (62) is slidably sleeved on the brake push rod (2), the return spring (61) is sleeved on the outside of the brake push rod (2) and its two ends abut against the spring seat (62) and the brake caliper (1) respectively, and the wear compensation component (63) is disposed between the spring seat (62) and the limiting step of the brake push rod (2).

9. A self-adjusting clearance anti-jamming device for a commercial vehicle air disc brake according to claim 8, characterized in that, The wear compensation component (63) adopts an elastic energy storage structure, which deforms synchronously with the axial compensation displacement of the brake push rod (2) to adjust the compression of the return spring (61).

10. A self-adjusting anti-jamming device for a commercial vehicle air disc brake according to claim 5, characterized in that, Both the main adjustable clearance transmission pair (41) and the secondary adjustable clearance transmission pair (42) include a lead screw and nut transmission structure. The driven parts of both are fixed relative to the brake push rod (2), and the driving parts are circumferentially driven by the self-adjusting shaft (31) through the bevel gear reversing pair.

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