Steering Wheel Conductor Layout for Heating and Grasp Detection

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Solution Overview

Problem

Conventional steering systems lack integration of both heater and touch sensor functions, which hampers the effectiveness of each individual feature.

Innovation Solution

A steering wheel system with a core part at ground potential, insulated conductors for heating and touch detection, and a controller that manages electrical connections based on control signals to ensure efficient operation of both functions, where the touch sensor conductor is positioned externally to protect the heating conductor from wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a heater and touch sensor are installed together in a steering wheel, then both heating and grasp detection functions are provided, but the structural complexity and difficulty of integration increase

Engineering Contradiction:
Improvefunctional integrationVSAvoidstructural complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines the heater and touch sensor into a single integrated steering wheel structure. The heating element and capacitive touch sensor are embedded together in the steering wheel cover, allowing both functions to operate simultaneously within one unified component rather than as separate add-on devices.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The steering wheel is designed to perform multiple functions simultaneously: it provides heating through the heating element while also enabling grasp detection through the capacitive touch sensor. This multi-functional design allows the same steering wheel structure to serve both thermal comfort and driver monitoring purposes.

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

2Use of energy by moving object

If the first conductor for heating is exposed on the exterior, then heating efficiency is improved, but the conductor becomes susceptible to wear and damage

Engineering Contradiction:
Improveheating efficiencyVSAvoidconductor durability
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The patent implements a nested conductor structure where the first conductor (heating element) is positioned inside the steering wheel cover, and the second conductor (touch sensor) is positioned on the exterior surface. This nesting arrangement protects the heating conductor from external wear while maintaining its heating function.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The steering wheel cover and insulation layers are positioned beforehand to protect the heating conductor from mechanical damage, wear, and environmental factors. This protective layering ensures the heating element's durability before it is exposed to operational stresses.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Measurement precision

If the second conductor for touch detection is placed on the exterior, then grasp detection sensitivity is improved, but the conductor may interfere with the heating function

Engineering Contradiction:
Improvegrasp detection sensitivityVSAvoidheating function stability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent divides the conductor system into two separate, insulated conductors: the first conductor for heating and the second conductor for touch detection. This segmentation allows each conductor to perform its specific function independently without electromagnetic interference, with the second conductor placed on the exterior for optimal touch sensitivity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces insulation layers as intermediary elements between the first and second conductors. These insulation layers prevent electromagnetic coupling and interference between the heating element and touch sensor, allowing both functions to operate simultaneously without mutual disruption.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Reliability

If insulation layers are added between conductors, then electrical interference is reduced, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improveelectrical isolationVSAvoidmanufacturing simplicity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent uses thin film insulation layers and flexible insulating materials to separate the conductors. These thin films provide effective electrical isolation while being easy to integrate into the steering wheel manufacturing process, avoiding the need for complex insulation structures.

Inventive Principle:
Principle #30Flexible shells and thin films

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 integration enhances the durability of the heating function while enabling effective grasp detection, improving the overall performance of the steering wheel by synergistically combining heating and touch detection capabilities.

Implementation Method 1

a first conductor insulated from the core part on the exterior of the core part for warming the steering wheel

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a capacitance measuring circuit for measuring the capacitance of the capacitive coupling generated between the second conductor and ground

Methodology Applied
Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentEP3805072B1Steering wheel, steering system, method for controlling steering wheel, and non-transitory computer-readable storage medium
Publication Date: 2024.03.06 AUTOLIV DEV AB
  • EP3805072B1 patent drawingFigure 1
  • EP3805072B1 patent drawingFigure 2
  • EP3805072B1 patent drawingFigure 3

AI summary

With the steering wheel, steering system, method of controlling steering, and non-temporary computer readable storage media, a grasp detection function can be applied to a steering wheel with a heating function, where one function can contribute to the improvement of the other function. The steering wheel (1) includes a core part (10) to which ground potential is supplied, a first conductor (12) provided on the exterior of the core part (10) and insulated from the core part (10), and a second conductor (14) provided on the exterior of the first conductor (12) and insulated from the first conductor (12) to sense gripping of the steering wheel (1).