Integrated Torque Limiter and Freewheel Assembly

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Solution Overview

Problem

Existing power transmission systems for tractors to driven machines require separate, large, and expensive torque limiting and freewheel devices, which are not easily protected by conventional means, violating regulatory requirements and necessitating modifications.

Innovation Solution

A compact mechanical assembly integrating a torque limiting device with automatic re-engagement and a freewheel mechanism, utilizing standard elements and distinct spring groups for each function, allowing for reduced size, conventional protection, and lower maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate torque limiting device and free wheel devices are mounted on the driven machine side, then the torque limiting function and freewheel function are achieved, but the device dimensions become large and expensive, and conventional protection means cannot be used

Engineering Contradiction:
Improvetorque limiting functionVSAvoiddevice dimensions
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The patent combines the torque limiting device and the free wheel device into a single integrated assembly mounted on the driven machine side. The torque limiting device includes clutch discs with springs and pawls, while the free wheel mechanism uses a ratchet and pawl system, both sharing a common housing and mounting structure. This merging eliminates the need for separate devices, reducing overall dimensions and allowing the use of conventional protection means.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integrated assembly performs multiple functions simultaneously: it provides torque limiting through the clutch discs and springs, enables automatic re-engagement through the pawl mechanisms, and allows freewheel operation through the ratchet and pawl system. This multi-functionality in a single device reduces the number of components needed and simplifies the overall transmission system.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If separate torque limiting device and free wheel devices are mounted on the driven machine side, then the torque limiting function and freewheel function are achieved, but the device cost increases and conventional protection means cannot be used

Engineering Contradiction:
Improvefreewheel functionVSAvoiddevice cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent combines the torque limiting device and the free wheel device into a single integrated assembly mounted on the driven machine side. The torque limiting device includes clutch discs with springs and pawls, while the free wheel mechanism uses a ratchet and pawl system, both sharing a common housing and mounting structure. This merging eliminates the need for separate devices, reducing overall dimensions and allowing the use of conventional protection means.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integrated assembly performs multiple functions simultaneously: it provides torque limiting through the clutch discs and springs, enables automatic re-engagement through the pawl mechanisms, and allows freewheel operation through the ratchet and pawl system. This multi-functionality in a single device reduces the number of components needed and simplifies the overall transmission system.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Device complexity

If the same springs and pawls are used for both torque limiting and free wheel functions, then the device structure is simplified, but the wear and maintenance requirements increase

Engineering Contradiction:
Improvestructure simplicityVSAvoidmaintenance needs
Core Design Contradiction:
Device complexityVSEase of repair

Solution Approach 1:

The patent divides the spring and pawl elements into two distinct groups: a first group of springs and first pawls for the torque limiting function, and a second group of springs and second pawls for the free wheel function. This segmentation allows each group to be optimized for its specific function and wear characteristics, with the first group subjected to high load with low frequency interventions and the second group subjected to lower load but much more frequent interventions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different design characteristics to different parts of the system: the first springs and pawls are designed for high-load torque limiting with corresponding material and dimensional specifications, while the second springs and pawls are designed for frequent engagement in the free wheel function with different wear resistance requirements. This local differentiation optimizes performance and maintenance for each specific function.

Inventive Principle:
Principle #3Local 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

The integrated device effectively interrupts torque and prevents reverse power transmission while allowing conventional protection, reducing size and maintenance needs, and adhering to regulatory requirements.

Implementation Method 1

The thrust of the ends 17 on the cylindrical element 21 generates a friction action on the surfaces 19 of the seats 18 that permits to transmit a torque value dependent on the spring preload force.

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

springs 15 of the group of springs 4 preloaded so as to apply a predetermined thrust on the first pawls 5

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 3

the tube 24 welded to the hole disk 27 carrying seats suitable to contain second pawl 9 pushed to the periphery by leaf springs 12 when the dragging of the freewheel 3 starts

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentEP3260719B1Assembly of a torque limiting device and freewheel in a mechanical transmission
Publication Date: 2018.10.24 BENZI & DI TERLIZZI
  • EP3260719B1 patent drawingFigure 1
  • EP3260719B1 patent drawingFigure 2
  • EP3260719B1 patent drawingFigure 3

AI summary

In an outer housing (1) and in an inner housing (3) in the assembly first pawls (5) are pushed by springs (15) to engage with the outer housing (21) and transmitting the torque from a tractor to a driven machine and second pawls (9), contained in the transmission shaft seats (2), are pushed towards the periphery by springs (12) to drag the free wheel (Fig. 1).