Elevator Machine Frame Noise Reduction via Varying Arm Cross Sections
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Solution Overview
Problem
Machine roomless elevator systems face challenges in maintaining low noise levels due to sound radiation from the machine frame, which is often designed for structural integrity but ends up increasing audible noise from machine operation.
Innovation Solution
The elevator machine frame is designed with a configuration of support surfaces and arms with varying cross sections and strategic arrangements to reduce noise radiation, including a unique distribution of arms on either side of the traction sheave axis, which alters the vibration profile and amplitude, thereby minimizing tonal noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the machine frame is designed with sufficient structural integrity to support the loads, then the strength and stability are improved, but the audible noise increases due to sound radiation from the frame
Solution Approach 1:
The patent applies local quality by varying the cross-sectional dimensions of different arms of the machine frame. Specifically, the first arm has different cross-sectional dimensions than the second and third arms, creating non-uniform structural properties that disrupt sound radiation patterns while maintaining adequate structural integrity for supporting the motor and traction sheave
Solution Approach 2:
The patent implements asymmetry by positioning arms with different cross-sectional characteristics at different locations around the traction sheave axis. The first arm extends in a first direction with cross-sectional dimensions different from the second arm extending in a second direction, creating an asymmetric configuration that reduces tonal noise radiation while preserving load-bearing capacity
2Area of stationary object
If the machine is supported in the hoistway without a machine room, then the building space requirement is reduced, but the noise from machine operation becomes more noticeable to passengers
Solution Approach 1:
The varied cross-sectional design of the frame arms provides localized acoustic optimization without requiring additional noise containment structures, enabling machine roomless installation while controlling noise radiation to acceptable levels for passenger comfort
Solution Approach 2:
The patent converts the potentially harmful effect of frame vibrations into a beneficial outcome by designing arm configurations that transform continuous tonal noise radiation into less noticeable vibrational patterns, thereby enabling machine roomless operation without compromising ride quality
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 configuration effectively reduces noise radiation, providing a quieter and more stable machine frame that supports the motor, brake, and traction sheave, enhancing the ride quality by minimizing audible noise and facilitating easier manufacturing and cost-effectiveness.
Implementation Method 1
at least one of the arms (46, 48, 50) has a different cross section at different longitudinal locations along the length of the arm... alters the vibration profile and amplitude, thereby minimizing tonal noise
Data Source
AI summary
An exemplary elevator machine frame includes a plurality of support surfaces configured to support at least one of a motor or a brake. A plurality of arms between the support surfaces maintain a desired alignment of support surfaces. At least one of the arms has a first cross section taken transverse to a longitudinal direction along a length of the arm at a first longitudinal location on the arm. That same arm has a second, different cross section at a second, different longitudinal location on the arm.