Steering Wheel Spoke Capacitive Sensing Against Heater Interference

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Solution Overview

Problem

The integration of a heater and capacitive sensor inside a steering wheel rim leads to decreased detection accuracy due to electromagnetic interference and temperature changes, making it difficult to accurately determine if a driver's hand is in contact or proximity to the wheel.

Innovation Solution

The capacitive sensor is positioned on the spoke of the steering wheel, separate from the heater, allowing for accurate detection of hand proximity without interference, and the controller adjusts detection areas based on capacitance changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a heater is provided inside the rim of the steering wheel to prevent driver's hand from feeling cold, then the driver's comfort is improved, but the detection accuracy of the capacitive sensor device is decreased due to electromagnetic interference and temperature changes

Engineering Contradiction:

Improvetemperature of steering wheel rimVSAvoiddetection accuracy of capacitive sensor

Core Design Contradiction:

TemperatureVSMeasurement precision

Solution Approach 1:

The patent divides the steering wheel into two separate functional zones: the rim area containing the heater for thermal comfort, and the spoke area containing the capacitive sensor for detection. This spatial segmentation eliminates the interference between the heater's electromagnetic field and the sensor's detection field, allowing both functions to operate independently without degrading each other's performance

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The capacitive sensor is extracted from the rim structure and relocated to the spoke structure. This extraction removes the sensor from the harmful electromagnetic environment created by the heater in the rim, while the sensor remains functionally integrated into the steering wheel system through its mounting on the spoke

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If a capacitive sensor is provided inside the rim to detect hand contact, then the detection function is achieved, but the detection accuracy is decreased due to electromagnetic field interference from the heater

Engineering Contradiction:

Improvehand detection functionVSAvoidelectromagnetic field interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The spoke structure serves as an intermediary mounting platform that electrically and physically connects the capacitive sensor to the steering wheel system without exposing the sensor to the heater's electromagnetic field. The spoke acts as a neutral zone that mediates between the sensor's detection function and the heater's thermal function

Inventive Principle:

Principle #24Intermediary (Mediator)

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 ensures high-accuracy detection of hand proximity to the steering wheel, unaffected by heater interference, while efficiently warming the rim.

Implementation Method 1

an electrode configured to be capacitively coupleable to an object to be detected, and includes a controller configured to detect a change in capacitance of the electrode, and determine whether the object is in proximity to the rim based on the change in the capacitance of the electrode

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentEP3951823B1Sensor device and steering wheel

Publication Date: 2025.09.03 ALPS ALPINE CO LTD

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AI summary

A capacitive sensor device for use with a steering wheel is provided. The steering wheel includes a rim and a spoke that is connected to the inner side of the rim, and the sensor device is provided on the spoke. The sensor device includes an electrode configured to be capacitively coupleable to an object to be detected, and includes a controller configured to detect a change in capacitance of the electrode, and determine whether the object is in proximity to the rim or the spoke based on the change in the capacitance of the electrode. The change in the capacitance occurs in response to the object being in proximity to the rim or the spoke.