Torque-Dependent Coupling for Disc Brake Wear Adjustment
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Solution Overview
Problem
Pneumatically actuated disc brakes in heavy commercial vehicles require mechanical boosting for clamping force due to limited brake cylinder pressure and size, necessitating a wear adjustment mechanism that maintains constant lift clearance despite pad wear, but existing devices face challenges in easy manual resetting and noise reduction during operation.
Innovation Solution
An adjusting device with a torque-dependent coupling using a ball cone clutch and ratchet mechanism, featuring a directional coupling with a ball ramp and friction clutch, allows for easy manual resetting and noise indication during operation, while maintaining a compact design and cost-effective manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional wear adjustor with ball ramp coupling is used, then automatic wear adjustment is achieved, but manual resetting becomes difficult due to 100% locking action of the freewheel
Solution Approach 1:
The locking mechanism is segmented into two distinct systems: a ball ramp coupling for automatic wear adjustment with selective engagement, and a ratchet coupling with positive restraint for manual resetting. This segmentation allows the automatic adjustment function to maintain reliable locking while the manual resetting function operates independently without being blocked by the freewheel's 100% locking action.
Solution Approach 2:
The ratchet coupling acts as an intermediary mechanism between the manual resetting operation and the threaded spindle. It provides a positive restraint that allows manual rotation in the resetting direction while preventing reverse rotation, thereby mediating between the operator's input and the adjustment mechanism without being affected by the freewheel's locking characteristic.
2Ease of operation
If a torque-dependent coupling with positive restraint is added, then manual resetting is facilitated, but device complexity increases
Solution Approach 1:
The ratchet coupling is merged with the existing ball ramp coupling and threaded spindle assembly, sharing common structural elements such as the drive ring, shaft, and mounting disc. This integration allows the torque-dependent coupling with positive restraint to be incorporated without proportionally increasing overall device complexity, as it leverages the existing mechanical framework.
3Ease of operation
If a ratchet coupling is used for manual resetting, then resetting ease is improved, but noise generation increases during operation
Solution Approach 1:
The noise generated by the ratchet coupling during manual resetting is converted into a beneficial acoustic signal that indicates the resetting process is occurring. The characteristic ratchet noise serves as feedback to the operator, confirming that the manual resetting operation is effective and the adjustment mechanism is responding, thereby transforming a harmful factor into a useful operational indicator.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables efficient wear adjustment with improved shake-proof features and noise indication during manual resetting, ensuring reliable operation and cost-effective production.
Implementation Method 1
axially on the opposite side of the drive ring, a ball ramp coupling with freewheel function (7, 8) is formed
Implementation Method 2
A cone clutch (9) is arranged between the clutch ring (8) on the output side and a spring sleeve (11) for the cylindrical spring (10)
Data Source
AI summary
A wear adjustor adjusts the wear of brake pads and a brake disc of a pneumatic disc brake having a rotary-lever-actuated brake application device. The adjustor is insertable into an adjusting spindle and attached to a caliper of the disc brake by way of a mounting disc. An axial bearing is formed axially on one side of a drive ring and a ball ramp coupling with a freewheel function is formed axially on the opposite side of the drive ring. The ball ramp coupling has balls, has the drive ring arranged at the drive-input side axially between the axial bearing and the balls thereof, and has a drive-output-side clutch ring. A cone clutch is arranged between the drive-output-side clutch ring and a spring sleeve for a cylindrical spring. A torque-dependent coupling with positive restraint is arranged axially between the cone clutch and the spring sleeve.