Support-Wheel Traction Sheave Assembly for Lighter Elevators

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Solution Overview

Problem

Existing tractor assemblies in elevators are heavy and costly due to their reliance on high-strength shafts and bearings, which compromises their load capacity and transmission stability.

Innovation Solution

A lightweight tractor assembly design featuring a traction sheave with support wheels that transmit load and motion, eliminating the need for conventional bearings and enhancing ventilation and heat dissipation through a hollow structure, while maintaining stability and ease of maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high-strength shafts and bearings are used in the tractor assembly, then load capacity and transmission stability are improved, but the apparatus weight and material costs increase significantly

Engineering Contradiction:

Improvetransmission stabilityVSAvoidapparatus weight

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent replaces the traditional mechanical bearing system with a magnetic field-based support system. The traction sheave is supported by magnetic forces generated by electromagnetic actuators, eliminating the need for high-strength mechanical shafts and bearings. This substitution maintains transmission stability through precise magnetic field control while dramatically reducing the weight of the tractor assembly.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental support parameter from mechanical contact forces (bearings) to magnetic field forces. By controlling the strength and distribution of magnetic fields, the system achieves stable support and transmission without the heavy mechanical components, effectively changing how load-bearing is accomplished in the tractor assembly.

Inventive Principle:

Principle #35Parameter changes

2Strength

If high-strength shafts and bearings are used in the tractor assembly, then load capacity is improved, but material costs increase

Engineering Contradiction:

Improveload capacityVSAvoidmaterial costs

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent replaces expensive high-strength mechanical shafts and bearings with electromagnetic actuators and magnetic field control systems. This substitution maintains load capacity through controllable magnetic forces while using more common, less expensive materials, thereby reducing overall material costs.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If conventional bearings and shafts are used, then transmission stability is ensured, but the device complexity and maintenance difficulty increase

Engineering Contradiction:

Improvetransmission stabilityVSAvoidmaintenance difficulty

Core Design Contradiction:

ReliabilityVSEase of repair

Solution Approach 1:

The patent replaces the complex mechanical bearing and shaft system with a magnetic field-based support system. This eliminates mechanical wear, friction, and contact fatigue issues inherent in conventional bearings, thereby maintaining transmission stability while dramatically simplifying maintenance requirements. The magnetic system has no moving contact parts, reducing maintenance to basic electromagnetic component checks.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical 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

The solution reduces the overall weight of the tractor assembly, improves heat dissipation, and simplifies assembly and maintenance while maintaining load capacity and transmission stability.

Implementation Method 1

transmission is enabled through friction between the first transmission surface of the traction sheave and the second transmission surface of the support wheel

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

a plurality of support wheels, configured to support the traction sheave, and each having a second transmission surface on a peripheral surface thereof

Methodology Applied

Scientific EffectRolling: Roller

Implementation Method 3

improves heat dissipation, and simplifies assembly and maintenance while maintaining load capacity and transmission stability

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 4

improves heat dissipation

Methodology Applied

Scientific EffectThermal Radiation: Thermal Radiation

Data Source

PatentUS11702321B2Traction machine assembly and elevator

Publication Date: 2023.07.18 OTIS ELEVATOR CO

AI summary

A tractor assembly and an elevator. The tractor assembly includes: a traction sheave, having a traction means fitting surface and a first transmission surface on a peripheral surface thereof; a plurality of support wheels, configured to support the traction sheave, and each having a second transmission surface on a peripheral surface thereof; and support wheel bases, configured to support the support wheels through support shafts, wherein the first transmission surface of the traction sheave is in transmitting cooperation with the second transmission surfaces of the plurality of support wheels respectively. According to the tractor assembly and elevator of the present application, the support wheels are disposed to achieve the transmitting cooperation of the traction sheave during operation of the elevator and support the traction sheave, thus omitting the load and drive bearings required by a conventional traction sheave.