Elevator Machine Thrust Bearing Retrofit for Axial Brake Control
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Solution Overview
Problem
Existing elevator systems face challenges in meeting contemporary regulatory braking requirements without the need for costly upgrades or space-consuming supplemental brakes, which also lead to increased rope wear and limited accessibility for maintenance.
Innovation Solution
The method involves retrofitting an elevator machine with a thrust bearing system by removing a cover plate from a bearing stand, securing an extension shaft and thrust bearing housing, and positioning the thrust bearing with its inner and outer races fixed to the extension shaft and housing, respectively, to limit axial motion and accommodate disc brake tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rope grabber system is added to meet braking requirements, then braking capability is improved, but space requirements increase and rope wear increases
Solution Approach 1:
The patent combines the braking function with the existing elevator machine structure by integrating a disc brake assembly onto the motor shaft. This merges the braking system with the drive mechanism, eliminating the need for a separate rope grabber system and reducing space requirements in the hoistway.
Solution Approach 2:
The motor shaft is designed to serve multiple functions: it acts as both the drive shaft for the elevator car and the mounting structure for the disc brake assembly. This multi-functionality eliminates the need for separate braking components and reduces overall system complexity.
2Reliability
If a rope grabber system is added to meet braking requirements, then braking capability is improved, but installation cost and complexity increase
Solution Approach 1:
The braking function is merged with the existing motor shaft assembly, utilizing the same structural components for both drive and braking functions. This integration simplifies installation by eliminating the need for separate mounting structures and reduces overall system complexity.
3Ease of operation
If axial movement of the main shaft is allowed, then bearing tolerance is relaxed, but disc brake operation precision deteriorates
Solution Approach 1:
The shaft system is segmented into two functional zones: the main shaft portion that allows axial movement for bearing tolerance, and the extension shaft portion that is rigidly connected to the disc brake assembly to provide the precise positioning required for brake operation. This segmentation allows each component to optimize its design for its specific function.
Solution Approach 2:
The extension shaft acts as an intermediary between the main shaft and the disc brake assembly. It transfers rotational motion from the main shaft while providing a rigid, precisely positioned mounting surface for the brake, thereby isolating the brake from axial movements of the main shaft.
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 allows for effective axial motion limitation, reducing the need for costly upgrades and space-consuming supplemental brakes, while maintaining accessibility and minimizing rope wear, thus addressing the challenges of meeting regulatory braking requirements without significant alterations to the elevator machine.
Implementation Method 1
positioning the thrust bearing in the bearing housing, wherein: an inner race of the thrust bearing is securely positioned against, and axially fixed to, the extension shaft, and an outer race of the thrust bearing is securely positioned against the bearing housing
Data Source
AI summary
Disclosed is a method for retrofitting an elevator machine with a thrust bearing, including removing, from a bearing stand, a first cover plate, providing access to an end portion of a motor shaft, securing an extension shaft against the end portion of the motor shaft, securing a thrust bearing housing against or axially offset from the bearing stand, positioning a thrust bearing in the bearing housing, wherein an inner race of the thrust bearing is securely positioned against, and axially fixed to, the extension shaft, and an outer race of the thrust bearing is securely positioned against the bearing housing, and securing a second cover plate to the bearing housing.