Planetary Transmission Assembly for Adjustable Roller Preload

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Solution Overview

Problem

Existing rolling-contact planetary transmissions lack a compact and robust design suitable for various applications, with varying requirements for preload and play between spindle nuts and planet rollers.

Innovation Solution

A set of components comprising standardized planet rollers and threaded spindles, along with different variants of spindle nuts that adjust for varying play and preload, ensuring a one-piece design with defined elasticity and rigidity, allowing for a simple and robust transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple component variants are used to adjust preload and play, then adaptability is improved, but device complexity increases

Engineering Contradiction:

Improveadaptability to varying preload and play requirementsVSAvoidcomplexity of assembly with multiple component variants

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention segments the preload adjustment function into a separate adjustment mechanism within the spindle nut, rather than requiring multiple complete component variants. The spindle nut is divided into functional sections: a fixed section for structural integrity and an adjustable section for preload modification, allowing one nut design to serve multiple preload requirements

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The spindle nut incorporates a dynamic adjustment mechanism that allows the preload on planet rollers to be modified during assembly or operation. This dynamic capability replaces the need for multiple static nut variants, enabling adaptability while maintaining a unified component design

Inventive Principle:

Principle #15Dynamics

2Manufacturing precision

If a one-piece spindle nut design is used, then manufacturing precision is improved, but adaptability worsens

Engineering Contradiction:

Improveprecision of tolerance chainsVSAvoidability to adjust preload for different applications

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The one-piece spindle nut is segmented into functional zones: a rigid fixed section for maintaining precision tolerance chains and an adjustable section for preload modification. This segmentation allows the nut to maintain manufacturing precision while providing adaptability through the adjustable mechanism

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The adjustable section of the spindle nut enables parameter changes in preload force without affecting the overall structural precision. By isolating the adjustment function to a specific mechanism within the one-piece nut, the design maintains tight tolerance chains while allowing preload variation for different applications

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If multiple nut variants are used to adjust play, then adaptability is improved, but ease of manufacture worsens

Engineering Contradiction:

Improveability to provide different play conditionsVSAvoidmanufacturing simplicity

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The spindle nut is designed as a universal component that performs multiple functions: structural support, preload application, and play adjustment. By integrating the play adjustment mechanism within a single nut design, the invention eliminates the need for multiple specialized nut variants, thereby improving ease of manufacture while maintaining adaptability

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The adjustment mechanism is segmented as a separate functional module within the spindle nut, allowing standardized manufacturing of the main nut body while enabling configurable play adjustment. This segmentation simplifies production by separating the constant structural elements from the variable adjustment elements

Inventive Principle:

Principle #1Segmentation

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 achieves a compact, robust, and adaptable design for rolling-contact planetary transmissions, enabling efficient force transmission with minimal tolerance chains and enhanced rigidity, suitable for diverse applications.

Implementation Method 1

rolling-contact planetary transmissions

Methodology Applied

Scientific EffectRolling contact: Roller

Implementation Method 2

In terms of friction, a true-lead planetary screw drive is generally superior to a simple movement thread

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS12516719B2Set of components for the assembly of true-pitch rolling-contact planetary transmissions

Publication Date: 2026.01.06 SCHAEFFLER TECHNOLOGIES AG & CO KG

AI summary

A set of components for the assembly of true-pitch rolling-contact planetary transmissions, in particular for electromechanical actuators of rear axle steering systems, comprises at least one threaded spindle, a number of planet rollers which can be placed onto the threaded spindle, at least one cage designed for guiding the planet wheels and provided as a drive element, and a plurality of different spindle nuts provided for receiving the planet wheels. The spindle nuts differ from one another in terms of the play that the planet rollers located between the threaded spindle and the spindle nut have.