Motorcycle Shift Sensor Layout for Compact Shift Linkage

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Solution Overview

Problem

Existing shift devices for straddle-type vehicles face challenges in providing a shift sensor due to the limited layout space, necessitating a sufficient length of the shift rod, which complicates the design and increases the device's size.

Innovation Solution

A shift device is designed with a shift sensor integrated into the shift shaft, functioning as a link arm to couple the shift shaft and shift rod, allowing compact arrangement and reducing the need for a long shift rod, thereby minimizing the device's size and component count.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a shift sensor is integrally provided on the shift rod, then the shift operation can be detected, but the shift rod must be sufficiently long which complicates the layout and increases device size

Engineering Contradiction:
Improveshift operation detectionVSAvoidshift rod length
Core Design Contradiction:
Measurement precisionVSLength of stationary object

Solution Approach 1:

The shift sensor is integrated with the shift shaft to form a unified structure. The sensor unit is provided on the shift shaft, eliminating the need for a separate long shift rod with attached sensor, thereby resolving the contradiction between detection capability and rod length requirement

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The shift shaft serves dual functions: it acts as both the rotational component for gear shifting and as the mounting structure for the shift sensor. This multi-functionality eliminates the need for a separate shift rod, achieving both detection and mechanical function with a single component

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

2Ease of manufacture

If the shift rod is made sufficiently long to accommodate the shift sensor, then the sensor can be provided, but the device size increases and layout becomes complicated

Engineering Contradiction:
Improvesensor provisionVSAvoiddevice size
Core Design Contradiction:
Ease of manufactureVSVolume of stationary object

Solution Approach 1:

By merging the shift sensor and shift shaft into a single integrated unit, the device occupies less space. The sensor unit is mounted directly on the existing shift shaft structure, eliminating the need for additional space that would be required for a separate long shift rod

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

Instead of extending the shift rod in a linear direction to accommodate the sensor, the sensor unit is mounted on the shift shaft in a different spatial arrangement, utilizing the radial or axial dimension of the shaft rather than requiring linear extension

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP4053434B1Shift device
Publication Date: 2025.07.23 SUZUKI MOTOR CORP
  • EP4053434B1 patent drawingFigure 1
  • EP4053434B1 patent drawingFigure 2
  • EP4053434B1 patent drawingFigure 3

AI summary

There is provided a shift device for a straddle-type vehicle that is configured to cause a transmission device to perform a shift change in accordance with rotation of a shift shaft. The shift device includes: a shift lever provided with an operation portion that is configured to receive a shift operation; a shift sensor provided on the shift shaft so as to be integrally rotatable with the shift shaft; and a shift rod that couples the shift lever and the shift sensor. The shift sensor is configured to detect the shift operation on the shift lever in accordance with a movement of the shift rod. The operation portion and the shift sensor are positioned at the same side in a manner of sandwiching the shift rod in a vehicle side view.