Shift Device Shaft Member Electromagnetic Shielding

Solution Overview

Problem

Existing shift devices for vehicles are prone to malfunction due to external magnetism when detecting the start of shift pedal operation, leading to increased complexity and manufacturing costs from the need for additional shielding components.

Innovation Solution

A shift device that eliminates the use of magnets by incorporating an electromagnetic field detection unit with a transmission circuit and reception circuit on a substrate, utilizing a shielding portion integral to the shaft member to shield the electromagnetic field and detect displacement based on voltage changes, thereby preventing malfunctions and reducing the number of parts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a magnet and magnetic sensor are used to detect shaft member displacement, then the start of shift pedal operation can be detected, but malfunction occurs due to external magnetism interference

Engineering Contradiction:

Improvedetection accuracyVSAvoidsystem stability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the magnetic detection system (magnet and magnetic sensor) with an electromagnetic field-based detection system. The shaft member itself is used as an electromagnetic shield that moves relative to the electromagnetic field detection unit, eliminating the need for separate magnets and magnetic sensors while providing more reliable detection immune to external magnetism.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The shaft member serves as an intermediary element that performs dual functions: it transmits the shift operation mechanically and simultaneously acts as an electromagnetic shield that modulates the electromagnetic field. This intermediary role allows the system to detect displacement through electromagnetic field changes without being susceptible to external magnetism.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a shielding member is added around the magnetic sensor to block external magnetism, then external magnetism influence is suppressed, but the number of parts increases and manufacturing cost increases

Engineering Contradiction:

Improveimmunity to external magnetismVSAvoidnumber of parts

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the shaft member's mechanical function with an electromagnetic shielding function. The shaft member itself is configured to act as the shield, integrating two functions (mechanical transmission and electromagnetic shielding) into a single component, thereby eliminating the need for separate shielding members and reducing overall system complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The shaft member is designed to perform multiple functions simultaneously: it serves as the mechanical transmission element for shift operation and as an electromagnetic shield for the detection system. This multi-functionality reduces the total number of components needed in the system.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If a shielding member is added around the magnetic sensor to block external magnetism, then external magnetism influence is suppressed, but manufacturing cost increases

Engineering Contradiction:

Improveimmunity to external magnetismVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges the shaft member's mechanical function with an electromagnetic shielding function. The shaft member itself is configured to act as the shield, integrating two functions (mechanical transmission and electromagnetic shielding) into a single component, thereby eliminating the need for separate shielding members and reducing overall system complexity.

Inventive Principle:

Principle #5Merging (Combining)

4Ease of operation

If a magnet is used to detect shaft member displacement, then the start of shift pedal operation can be detected, but the system becomes susceptible to external magnetism interference

Engineering Contradiction:

Improvedetection capabilityVSAvoidexternal magnetism influence

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the magnetic detection system (magnet and magnetic sensor) with an electromagnetic field-based detection system. The shaft member itself is used as an electromagnetic shield that moves relative to the electromagnetic field detection unit, eliminating the need for separate magnets and magnetic sensors while providing more reliable detection immune to external magnetism.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Accurate detection of shift pedal operation is ensured without external magnetism interference, reducing part count and manufacturing costs, while maintaining reliable shielding and smooth operation.

Implementation Method 1

a transmission circuit which is configured to generate an electromagnetic field by supplying a high-frequency signal

Methodology Applied

Scientific EffectElectromagnetic field generation: Electromagnetic Induction

Implementation Method 2

a reception circuit which is formed in the transmission circuit and is configured to receive the electromagnetic field generated by the transmission circuit to generate a voltage

Methodology Applied

Scientific EffectElectromagnetic field reception: Electromagnetic Induction

Implementation Method 3

a shielding portion which is close to the electromagnetic field detection unit at a position corresponding to the displacement of the shaft member and which is configured to shield the electromagnetic field generated by the transmission circuit

Methodology Applied

Scientific EffectElectromagnetic shielding: Faraday Cage

Data Source

PatentEP3865737B1Shift device

Publication Date: 2022.08.10 ASAHI DENSO KABUSHIKI KAISHA

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AI summary

A shift device includes: a shaft member which can be displaced according to a shift operation of a shift pedal of a vehicle; a housing which can accommodate the shaft member in a displaceable manner and move integrally with the shaft member in a state where the shaft member reaches a displacement end to perform a gear-shifting operation of the vehicle; and a detecting unit for detecting displacement of the shaft member with respect to the housing. The detecting unit includes: an electromagnetic field detection unit in which a transmission circuit which generates an electromagnetic field by supplying a high-frequency signal and a reception circuit which is formed in the transmission circuit and can receive the electromagnetic field generated by the transmission circuit to generate a voltage are formed on a substrate and which is formed along a displacement direction of the shaft member; a shielding portion which is close to the electromagnetic field detection unit at a position corresponding to the displacement of the shaft member and shields the electromagnetic field generated by the transmission circuit of the electromagnetic field detection unit; and a displacement detection unit which can detect the displacement of the shaft member based on a voltage change in the reception circuit caused by shielding of the electromagnetic field by the shielding portion.