Master Cylinder Positioning in Straddle Vehicle Footrest Bracket
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Solution Overview
Problem
Conventional straddle-type vehicles, such as cruiser motorcycles, face issues with the external appearance being impaired due to the exposure of the master cylinder and reservoir, and increased complexity in assembly due to the need for additional components when the braking unit is positioned near the engine or exhaust pipe, leading to potential damage and reduced productivity.
Innovation Solution
The master cylinder of the braking unit is positioned behind the footrest bracket with a horizontal cylinder axis, overlapping with the footrest bracket, and the reservoir is placed on the inner side of the vehicle body to overlap with the footrest and brake pedal, allowing the master cylinder to be located lower and hidden from view, reducing exposure to heat and debris while simplifying the assembly by eliminating the need for additional brackets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the master cylinder and reservoir are placed in the vicinity of the footrest, then the braking unit can be positioned close to the rider's feet for ease of operation, but the external appearance of the vehicle is impaired due to exposure of these components
Solution Approach 1:
The master cylinder is nested within the footrest bracket structure, specifically positioned behind the footrest bracket such that its front half overlaps with the bracket. This nesting arrangement allows the braking unit to be accessible near the footrest while the master cylinder remains hidden, resolving the contradiction between operational accessibility and aesthetic appearance.
2Device complexity
If the master cylinder is disposed near the engine or exhaust pipe, then the braking unit can be compactly arranged, but the temperature of the hydraulic fluid increases due to heat from these components
Solution Approach 1:
The master cylinder is extracted from the proximity of heat-generating components (engine and exhaust pipe) and repositioned behind the footrest bracket. This extraction eliminates the harmful thermal influence while maintaining compact overall arrangement through the overlapping configuration with the footrest bracket.
3Device complexity
If the master cylinder is disposed in the vicinity of the front wheel, then the braking unit can be compactly arranged, but the master cylinder is exposed to damaging substances and dirty state from flying stone, muddy water, and sandy dust
Solution Approach 1:
The master cylinder is nested within the footrest bracket structure, positioned behind it such that the bracket serves as a protective barrier. This nesting arrangement shields the master cylinder from debris (flying stone, muddy water, sandy dust) while maintaining compact braking unit configuration.
4Object-affected harmful factors
If the master cylinder and reservoir are spaced apart from the brake pedal, then heat and debris exposure is reduced, but the number of components increases and assembling work becomes complicated
Solution Approach 1:
The master cylinder is merged with the footrest bracket structure by positioning it behind the bracket such that its front half overlaps with the bracket. This merging eliminates the need for separate mounting brackets, reducing component count while maintaining protective spacing from heat and debris sources.
5Reliability
If additional brackets are provided for attaching the master cylinder and reservoir, then proper positioning and protection are achieved, but assembling work is complicated and productivity decreases
Solution Approach 1:
The master cylinder is merged with the existing footrest bracket structure, utilizing the bracket's space and structure for mounting. This eliminates the need for additional dedicated mounting brackets, simplifying assembly procedures while ensuring accurate positioning and reliable attachment of the braking unit components.
Data Source
AI summary
A straddle-type vehicle including a vehicle body frame having a vehicle body, an engine supported by the vehicle body frame, a footrest disposed to a front lower portion of the engine, a footrest bracket for attaching the footrest to the vehicle body frame, and a braking unit. The braking unit includes a brake pedal arranged in the vicinity of the footrest and turned by a pedaling force of the rider, a master cylinder operated by the brake pedal, and a reservoir that supplies a hydraulic fluid to the master cylinder. The master cylinder is disposed behind the footrest bracket such that a cylinder axial line thereof is substantially horizontal and at least a part of a front half thereof overlaps with the footrest bracket as viewed from both a side of a vehicle and a bottom side thereof.