Friction Roller Reducer Radial Displacement Mechanism

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Solution Overview

Problem

Conventional friction roller reducers experience inefficiencies due to uneven surface pressure and displacement issues with intermediate rollers as torque changes, leading to reduced transmission efficiency in electric automobile drive systems.

Innovation Solution

The friction roller reducer incorporates a pivot mechanism that allows smooth radial displacement of intermediate rollers in response to changes in the axial thickness of the loading cam apparatus, ensuring uniform surface pressure and improved torque transmission through a design featuring concentric sun and ring-shaped rollers, and a loading cam apparatus with cam surfaces that adjust pressure distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional friction roller reducers are used with fixed intermediate rollers, then the structure is simple, but the surface pressure becomes uneven and transmission efficiency decreases when torque changes

Engineering Contradiction:
Improvetransmission efficiencyVSAvoidstructure complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent applies the dynamics principle by making the intermediate rollers movable rather than fixed. The intermediate rollers are designed to displace radially in response to torque changes, allowing them to maintain optimal contact pressure with the sun roller and ring gear. This dynamic adjustment capability resolves the contradiction by improving transmission efficiency through adaptive pressure distribution while accepting increased structural complexity.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent employs parameter changes by allowing the position and contact pressure parameters of the intermediate rollers to vary with torque conditions. As torque changes, the intermediate rollers automatically adjust their radial position and contact pressure, optimizing transmission efficiency across different operating conditions. This parameter variability resolves the efficiency loss issue while requiring a more complex support structure.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If intermediate rollers are made movable to adjust surface pressure, then transmission efficiency improves, but the mechanism complexity increases

Engineering Contradiction:
Improvetorque transmission reliabilityVSAvoidpivot mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The pivot mechanism enables dynamic adjustment of intermediate roller positions based on torque variations. This dynamic capability improves torque transmission reliability by maintaining consistent surface pressure and contact conditions, while the mechanism itself adds structural complexity through the pivot joints and support structures required.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The intermediate rollers are designed to self-adjust their positions through the pivot mechanism in response to torque changes, without requiring external control systems. This self-service capability improves reliability by automatically maintaining optimal contact conditions, while the pivot mechanism structure necessarily increases device complexity.

Inventive Principle:
Principle #25Self-service

3Stress or pressure

If the loading cam apparatus is made adjustable in axial thickness, then surface pressure uniformity improves, but the device complexity increases

Engineering Contradiction:
Improvesurface pressure uniformityVSAvoidloading cam apparatus complexity
Core Design Contradiction:
Stress or pressureVSDevice complexity

Solution Approach 1:

The loading cam apparatus is designed with adjustable axial thickness that can be modified based on torque conditions. This parameter adjustment capability allows the apparatus to maintain uniform surface pressure distribution across the contact surfaces, improving pressure uniformity while necessarily increasing the complexity of the cam structure and adjustment mechanisms.

Inventive Principle:
Principle #35Parameter changes

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 enhances transmission efficiency and maintains uniform surface pressure, allowing for longer electric vehicle range per charge by effectively managing torque changes and reducing vibration and noise.

Implementation Method 1

a loading cam apparatus with cam surfaces that adjust pressure distribution

Methodology Applied
Scientific EffectCam mechanism: Cam

Implementation Method 2

Friction roller reducers that can be used for this purpose... use of a friction roller reducer as at least the first-stage roller is feasible

Methodology Applied
Scientific EffectRolling contact: Roller

Data Source

PatentEP2687752B1Friction roller type deceleration device and drive device for electric automobile
Publication Date: 2019.08.21 NSK LTD
  • EP2687752B1 patent drawingFigure 1
  • EP2687752B1 patent drawingFigure 2(A)~2(B)
  • EP2687752B1 patent drawingFigure 3

AI summary

Construction of a friction roller reducer is achieved wherein displacement of intermediate rollers 19 due to the change in thickness in the axial direction of loading cam apparatuses 7a can be performed smoothly, and excellent transmission efficiency can be obtained. Long guide holes 35 that are long in the radial direction of a sun roller 4a and ring-shaped roller 5a are provided in guide blocks 34 that are fastened to a support frame for supporting the end sections of rotation shafts 20 of intermediate rollers 19. The outer rings of ball bearings 36, of which the inner rings are fitted around and fastened to the outside of the end sections of the rotation shafts 20, engage with the long guide holes 35 so as to be able to displace in the radial direction of the sun roller 4a and the ring-shaped roller 5a.