Externally Adjustable Clutch Assembly for Hoist Torque Control

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Solution Overview

Problem

Existing clutches in hoist systems lack an efficient mechanism to prevent excessive torque transmission without requiring disassembly or adjustment of components, which can lead to mechanical wear and reduced performance over time.

Innovation Solution

An externally adjustable clutch assembly featuring a gear drive mechanism that allows for selective rotation of a wheel, causing axial movement of the clutch housing cap, thereby adjusting the spring bias between torque transfer surfaces, allowing for external regulation of the clutch's torque transfer without disassembly, using a worm drive to adjust the spring force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the clutch is adjusted by tightening a compression nut positioned outside of a spring on the threaded end of a rod, then the clutch can be adjusted externally, but the adjustment mechanism becomes complex and requires disassembly of the casing

Engineering Contradiction:
Improveexternal adjustabilityVSAvoidadjustment mechanism complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The clutch housing is divided into a stationary base portion and a movable cap portion that can shift axially independently. The adjustment mechanism is segmented into a worm gear drive system with a shaft extending through the cap, allowing external adjustment without disassembling the entire clutch assembly. This segmentation enables independent movement of the cap to adjust spring compression while keeping the base fixed.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A locking element acts as an intermediary between the movable cap and the stationary base. This locking element engages with both portions to prevent relative movement during operation, yet can be disengaged to allow axial movement of the cap for adjustment purposes. The locking element mediates between the need for stability during operation and the need for adjustability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the spring bias is adjusted frequently to maintain clutch performance, then the clutch performance is maintained, but mechanical wear increases and lifespan is reduced

Engineering Contradiction:
Improveclutch performance consistencyVSAvoidclutch lifespan
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The adjustment mechanism incorporates a locking element that provides positional feedback and stability. Once the cap is moved to the desired adjustment position, the locking element engages to maintain that position precisely, preventing drift and ensuring consistent clutch performance without requiring frequent readjustments. This feedback mechanism reduces the frequency of adjustments needed.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The clutch assembly is designed with an externally accessible adjustment mechanism that allows the optimal spring bias to be set beforehand. The locking element pre-secures the adjustment at the correct position, eliminating the need for frequent subsequent adjustments. This preliminary setup action reduces long-term mechanical wear by establishing the correct operating parameters in advance.

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If the clutch housing cap is made movable to allow adjustment, then external adjustment is enabled, but rotational stability during operation may be compromised

Engineering Contradiction:
ImproveadjustabilityVSAvoidrotational stability
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The clutch design implements dynamic characteristics by allowing the cap to move axially for adjustment purposes while maintaining rotational stability during operation through the locking element. The system transitions from a static, fixed design to a dynamic one where the cap can shift position during maintenance but remains stable during clutch operation. This dynamic approach enables both adjustability and operational stability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The locking element creates an asymmetric constraint system where axial movement is permitted during adjustment but rotational movement is prevented during operation. The geometry of the locking element and its engagement features are asymmetrically designed to allow linear displacement of the cap while constraining rotational degrees of freedom, thereby achieving both adjustability and rotational stability.

Inventive Principle:
Principle #4Asymmetry

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

Enables precise control of torque transmission, preventing excessive torque and maintaining clutch performance by allowing external adjustment of the spring bias, thus extending the lifespan of the clutch and reducing mechanical wear without the need to open the casing.

Implementation Method 1

a spring element (26) disposed axially between the clutch housing cap and the first rotary member and configured to bias the opposed first and second torque transfer surfaces axially towards each other

Methodology Applied
Scientific EffectElastic compression: Elasticity

Implementation Method 2

the gear drive (28) comprising a wheel (29) configured to rotate about the clutch axis and a shaft (30) in engagement with the wheel and configured to rotate about an adjustment axis (31) to thereby selectively rotate the wheel about the clutch axis

Methodology Applied
Scientific EffectMechanical advantage: Mechanical Advantage

Implementation Method 3

a first rotary member (20) having a first torque transfer surface (23)... a second rotary member (21) having a second torque transfer surface (24) opposing said first torque transfer surface at a slip joint (25)

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3218297B1Externally adjustable clutch
Publication Date: 2020.08.05 COLUMBUS MCKINNON CORP
  • EP3218297B1 patent drawingFigure 1
  • EP3218297B1 patent drawingFigure 2
  • EP3218297B1 patent drawingFigure 3

AI summary

An adjustable clutch assembly comprising a base portion, a clutch housing cap, a first rotary member having a first torque transfer surface rotatable about a clutch axis and a second rotary member having a second torque transfer surface opposing said first torque transfer surface, a spring element configured to bias the opposed first and second torque transfer surfaces towards each other, a gear drive comprising a wheel engaging the clutch housing cap and a shaft engaging the wheel, a locking element constraining rotational movement of the clutch housing cap relative to the base portion, the gear drive, base portion, locking element and clutch housing cap configured such that selective rotation of the wheel about the clutch axis causes axial movement of the clutch housing cap along the clutch axis relative to the base portion, whereby the bias of the spring may be adjusted.