Friction Device Coil Spring Actuator Positioning

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Solution Overview

Problem

Actuators, such as those using planetary roller spindle drives, require continuous holding current to maintain position, risking unintended clutch closure during power failures, and existing solutions like wrap springs do not effectively manage friction for efficient operation.

Innovation Solution

A component group with a friction device featuring a coil spring that influences friction between rotatable components, increasing friction in one direction to lock the system during malfunctions and reducing friction when driving against a load, thereby eliminating the need for continuous holding current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If continuous holding current is applied to maintain actuator position, then system stability is improved, but energy consumption increases and risk of unintended clutch closure during power failures occurs

Engineering Contradiction:

Improvesystem stabilityVSAvoidholding current consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces the electrical holding mechanism (continuous current) with a mechanical friction device consisting of a coil spring and friction elements. The coil spring generates frictional forces that passively maintain the actuator components in position without requiring continuous electrical power, thus eliminating holding current consumption while maintaining system stability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The friction device is designed to automatically maintain actuator position through the elastic forces of the coil spring without external control or continuous energy input. The system serves itself by using the spring's inherent elastic properties to generate the necessary frictional holding force, eliminating the need for active electrical control during idle periods.

Inventive Principle:

Principle #25Self-service

2Use of energy by moving object

If friction device with coil spring is introduced to eliminate holding current, then energy consumption is reduced, but device complexity increases

Engineering Contradiction:

Improveholding current consumptionVSAvoidfriction device structure

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent integrates the coil spring and friction elements into the existing actuator structure, combining multiple functions (position maintenance, friction control) into a single integrated component assembly. The friction device is merged with the planetary roller spindle drive components, eliminating the need for separate holding mechanisms and reducing overall system complexity despite adding friction control capabilities.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If friction is increased to lock system during malfunctions, then reliability during power failures is improved, but friction losses during normal operation increase

Engineering Contradiction:

Improveclutch position maintenance during power failureVSAvoidfriction losses during operation

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent designs the friction device with dynamically adjustable friction characteristics. The coil spring's frictional force varies based on the operational state: during normal operation, the friction is minimized to reduce energy losses, while during malfunctions or power failures, the friction automatically increases to lock the system and maintain clutch position. This dynamic adaptation is achieved through the elastic properties of the coil spring and the interaction with friction elements.

Inventive Principle:

Principle #15Dynamics

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 coil spring-based friction device allows for efficient operation by reducing or eliminating the holding current requirement while maintaining system stability during power failures, ensuring the clutch remains open and preventing unintended closure.

Implementation Method 1

A coil spring is disposed between the components that are rotatable relative to one another, the coil spring influencing the degree of efficiency/the friction upon a relative rotation of the components

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The spindle, which is axially fixed and driven to rotate by an electric motor, for instance, is rotated relative to the spindle nut, which is fixed against relative rotation, in a way to force the spindle nut to be axially displaced due to the frictional rolling of the planetary bodies in the grooves of the spindle nut

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS10247253B2Component group with a frictional device

Publication Date: 2019.04.02 SCHAEFFLER TECHNOLOGIES AG & CO KG

AI summary

Embodiments of the present invention relate to a component group with a friction device with at least two components that are rotatable relative to one another, in particular for actuating a clutch of a vehicle, wherein a coil spring influencing the degree of efficiency, the friction is disposed between the components that are rotatable relative to one another and wherein the component group with a friction device is integrated in a transmission or an actuator, or both.