Torque Limiter with Ball Detent and Integrated Brake
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing torque limiters in AC-driven mining machinery, such as crusher mills, often malfunction due to large momentary torque spikes, leading to catastrophic failures and requiring costly and time-consuming repairs, with existing solutions like SAFESET limiters being expensive, prone to wear, and requiring part replacements.
Innovation Solution
The use of Brunel Corporation's torque limiter design with radially or axially mounted safety elements, featuring balls held in detent pockets by spring forces, which disconnect and reengage without frictional drag, and an integrated brake disc to prevent movement during maintenance, reducing costs and maintenance complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional friction-based torque limiters are used, then torque limiting function is provided, but friction causes wear and requires part replacements
Solution Approach 1:
The patent replaces friction-based mechanical torque limiting with a ball-detent mechanical system. Balls are held in detent pockets by spring forces during normal operation, and when torque exceeds the spring force, balls are ejected from detent pockets to disconnect the drive. This substitution eliminates continuous friction contact while maintaining torque limiting functionality.
2Reliability
If SAFESET torque limiters are used, then torque protection is provided, but they are costly and require long lead time
Solution Approach 1:
The torque limiter is divided into modular components: multiple ball-detent assemblies arranged radially, spring mechanisms, locking balls, and detent pockets. This segmentation allows for simplified manufacturing of individual components, easier assembly, and reduced overall cost compared to monolithic designs like SAFESET limiters.
3Reliability
If shear pins are used for torque limiting, then overload protection is provided, but they are not consistent in releasing drive and must be replaced
Solution Approach 1:
The ball-detent system with spring forces provides automatic reset capability. After overload disconnection, the springs automatically retract the balls back into detent pockets, resetting the torque limiter without manual intervention. This eliminates the need for replacement or complex resetting procedures required by shear pins.
4Reliability
If torque limiter disengages during maintenance, then torque protection is activated, but mill movement presents safety hazard
Solution Approach 1:
The brake system is merged with the torque limiter assembly, with the brake disc integrated into the torque limiter housing and the brake caliper positioned to engage the disc. This combination ensures that when torque limiting occurs, the brake automatically applies to hold the mill stationary, addressing both torque protection and safety requirements in a single integrated system.
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
This solution provides a cost-effective, reliable, and efficient torque limiting mechanism that minimizes downtime and eliminates the need for spare parts after overload events, allowing for quick reset and safe maintenance without skilled personnel, suitable for both low and high-speed applications.
Implementation Method 1
balls held down in detents (drill point type holes) by spring forces acting on locking balls
Implementation Method 2
the provision of a large brake disc and brake caliper integrated in the torque limiter. When the torque limiter is disengaged, the brake caliper is activated to hold the mill drive stationary
Data Source
AI summary
A displaceable drive ball safety element type torque limiter is installed in a variable speed AC motor drive crusher mill drive which can include a selective operable locking brake to hold the crusher components stationary during maintenance operations.