Multiphase Brushless Motor Starter for MT Straddled Vehicle

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Solution Overview

Problem

In MT-type straddled vehicles, the arrangement of components in the region higher than the crankcase is limited, restricting flexibility and potentially leading to a decline in starter motor functions.

Innovation Solution

Employing a multiphase brushless motor that serves as both a starter motor and a generator, allowing the starter motor to be removed from the region above the crankcase, thereby creating more space for other components and improving heat dissipation for the motor driver.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the starter motor is arranged in the region higher than the crankcase, then the starter motor can be positioned close to the crankshaft for efficient starting, but the space for other components is limited and arrangement flexibility is reduced

Engineering Contradiction:
Improvestarter motor functionVSAvoidarrangement flexibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The starter motor is extracted from the region higher than the crankcase and repositioned to the end portion of the crankshaft. This extraction resolves the spatial conflict by removing the starter motor from the constrained upper region, thereby improving arrangement flexibility for other components while maintaining starting function through the alternative positioning at the crankshaft end

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The starter motor is repositioned from a vertical arrangement (higher than crankcase) to a horizontal arrangement (end portion of crankshaft). This dimensional change allows the starter motor to maintain functional proximity to the crankshaft while freeing up the vertical space for other components, thus resolving the spatial contradiction

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

2Temperature

If the motor driver is arranged in a space between the side cover, air cleaner, and battery, then heat dissipation is improved through air flow, but the arrangement space is constrained

Engineering Contradiction:
Improveheat dissipationVSAvoidarrangement space
Core Design Contradiction:
TemperatureVSArea of stationary object

Solution Approach 1:

The motor driver is positioned in the interstitial space between the side cover, air cleaner, and battery, utilizing the air flow path as a thermal mediator. The air flow that passes through this region serves as a cooling medium for the motor driver, enabling effective heat dissipation in a constrained space without requiring dedicated cooling structures

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The motor driver is arranged in the vertical dimension between the side cover and air cleaner, rather than occupying horizontal space. This vertical positioning utilizes the existing air flow path in the vertical direction, enabling heat dissipation through convection while minimizing the horizontal footprint and preserving arrangement flexibility

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

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 configuration enhances flexibility in the arrangement of components above the crankcase while maintaining the functionality of the starter motor, thereby improving the overall design and performance of the MT-type straddled vehicle.

Implementation Method 1

a multiphase brushless motor that also serves as a power generator is provided as the starter motor at the end part of the crankshaft

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a multiphase brushless motor that also serves as a power generator is provided as the starter motor at the end part of the crankshaft

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

an air cleaner configured to clean the air to be supplied to the engine

Methodology Applied
Scientific EffectPhysical filtration: Filter (physical)

Implementation Method 4

The motor driver is arranged in a space between the side cover, and the air cleaner and the battery so that at least a part of the motor driver overlaps both the air cleaner and the battery in view of the left-right direction. This arrangement allows the motor driver and the battery to keep radiating the heat through the air

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP4088996B1Mt-type straddled vehicle
Publication Date: 2025.03.05 YAMAHA MOTOR CO LTD
  • EP4088996B1 patent drawingFigure 1(a)~1(b)
  • EP4088996B1 patent drawingFigure 2
  • EP4088996B1 patent drawingFigure 3

AI summary

The MT type straddled vehicle according to the present teaching includes an engine, a multi-phase brushless motor that is provided at one end portion of a crankshaft of the engine and starts the engine and is driven by the engine to generate electricity, and a motor driver that performs switching of an electric current that is to be supplied to the multi-phase brushless motor. The air cleaner and the battery are arranged next to each other in the front-back direction so that both of the air cleaner and the battery lie over two regions that are defined by division of a space including the MT type straddled vehicle by a center plane passing through the center of the MT type straddled vehicle in the left-right direction and extending both in the up-down direction and the front-back direction of the MT type straddled vehicle. The motor driver is arranged in a space between the side cover, and the air cleaner and the battery so that at least a part of the motor driver overlaps both the air cleaner and the battery in view of the left-right direction. The air cleaner cleans the air to be supplied to the engine. The side cover covers at least a part of each of the air cleaner and the battery in view of the left-right direction.