Integrated Vehicle Axle Gear Layout for Variable Torque Reduction

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Solution Overview

Problem

Heavy vehicles require a more extensive range of torque reduction ratios than conventional systems provide, especially under varying load conditions, and existing integrated torque reduction systems are bulky, difficult to mount, and complex to maintain.

Innovation Solution

An axle with an integrated reducing gear system featuring a differential gear, planet gears, and an epicyclic gear mechanism, along with elastic means and air-actuated valve systems, allowing for adjustable transmission ratios and compact design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional gearbox device is used for torque reduction, then the reduction ratio is sufficient for normal vehicles, but it provides insufficient reduction ratios for heavy vehicles under varying load conditions

Engineering Contradiction:
Improverange of torque reduction ratiosVSAvoidnumber of reduction stages
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements nested reduction mechanisms where a first reduction mechanism (planetary gear set) is integrated within the axle housing, and a second reduction mechanism (worm gear) is nested within the wheel hub. This nested configuration enables multiple reduction ratios to be achieved within a compact space, providing the required adaptability for heavy vehicles without proportionally increasing device complexity.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent employs a selectable reduction ratio mechanism that allows the axle to dynamically switch between different reduction ratios based on load conditions. The system can select between a first reduction ratio (when the vehicle is unloaded) and a second reduction ratio (when the vehicle is loaded), enabling adaptive torque reduction that optimizes performance across varying operating conditions.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If an integrated torque reducing system is implemented in the wheel hub, then the number of reduction ratios is doubled, but the system dimensions become particularly large

Engineering Contradiction:
Improvenumber of reduction ratiosVSAvoidsystem dimensions
Core Design Contradiction:
Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The patent integrates the second reduction mechanism (worm gear) within the wheel hub assembly, nesting it inside the existing brake system components. The planet carrier assembly is positioned within the axle housing, and the worm gear mechanism is contained within the wheel hub, utilizing the internal space efficiently. This nesting approach enables multiple reduction ratios without proportionally increasing the external dimensions of the axle system.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent utilizes the axial dimension within the wheel hub to accommodate the worm gear mechanism, arranging components along the axial direction rather than requiring increased radial or lateral dimensions. The brake caliper and brake disc are positioned to accommodate the worm gear mechanism in the axial direction, enabling compact integration of multiple reduction stages without increasing the overall width or height of the wheel assembly.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If an integrated torque reducing system with multiple components is used, then torque reduction capability is improved, but the system becomes hard to mount and complicated to maintain

Engineering Contradiction:
Improvetorque reduction capabilityVSAvoidassembly and maintenance complexity
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent divides the reduction system into two independent but integrated mechanisms: a first reduction mechanism (planetary gear set) housed in the axle housing, and a second reduction mechanism (worm gear) housed in the wheel hub. This segmentation allows each mechanism to be manufactured and assembled separately, then integrated as a complete assembly, simplifying manufacturing and maintenance operations while maintaining the capability for multiple reduction ratios.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent merges the reduction mechanisms with existing axle components by integrating the planet carrier assembly with the differential gear assembly and the worm gear mechanism with the brake system. This merging approach allows the reduction functions to be incorporated into the existing structural framework, reducing the number of separate components that need to be individually assembled and maintained.

Inventive Principle:
Principle #5Merging (Combining)

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 system provides a versatile, compact, and economical solution for torque reduction, reducing fuel consumption and emissions, and simplifies assembly and maintenance, while being adaptable to different vehicle types and brake systems.

Implementation Method 1

elastic means, which are operatively interposed between each inner end portion of the axle shafts and the gear train carrier and are configured to impart a force along a longitudinal axis to the axle shafts so as to hold them in an operative position

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a planet gear mechanism comprising a plurality of planet gears arranged around the driveshaft and configured to engage with the driveshaft and with the axle shafts

Methodology Applied
Scientific EffectEpicyclic Gearing: Epicyclic Gearing

Implementation Method 3

a differential gear assembly, which is configured to differentiate the torque coming from the driveshaft between a pair of axle shafts of the axle

Methodology Applied
Scientific EffectDifferential Gearing: Gear

Data Source

PatentEP4107023B1Vehicle axle comprising an improved integrated reducing gear system
Publication Date: 2024.05.29 IVECO SPA
  • EP4107023B1 patent drawingFigure 1
  • EP4107023B1 patent drawingFigure 2
  • EP4107023B1 patent drawingFigure 3~4

AI summary

A vehicle axle (1), wherein the transmission ratio between the respective axle shaft (4, 5) and the wheel hub (6) is obtained by means of a pair of toothings (33, 34) and is different from the transmission ratio between the respective axle shaft (4, 5) and the wheel hub (6) obtained by means of one of the preceding toothings (33) and a transmission (37), said axles shafts (4, 5) being able to slide along a longitudinal axis of the axle (1) by means of actuator means.