Dual-Seal Piston Assembly for Low-Friction Hydraulic Braking
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Solution Overview
Problem
Existing piston assemblies for human-powered vehicles, such as bicycles, face challenges in achieving improved sliding performance and cost-effective manufacturing within hydraulic systems, particularly in hydraulic braking systems, where seals often fail to maintain reliable contact with the cylinder bore during actuation.
Innovation Solution
The piston assembly incorporates a primary seal made of resin materials like polytetrafluoroethylene or polyimide-filled polytetrafluoroethylene, combined with a secondary seal of rubber, and utilizes a coil spring biasing mechanism to ensure consistent contact with the cylinder bore, along with a modular design allowing for easy assembly and material optimization using different materials for various parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional seal materials are used in the piston assembly, then manufacturing cost is reduced, but sliding performance with respect to the cylinder bore deteriorates
Solution Approach 1:
The patent applies composite materials by combining resin material (such as polytetrafluoroethylene or polyimide-filled polytetrafluoroethylene) for the primary seal with rubber material for the secondary seal. This composite sealing structure maintains reliable contact with the cylinder bore during actuation while enabling cost-effective manufacturing, resolving the contradiction between manufacturing cost and sliding performance.
2Device complexity
If a single seal material is used for both seals, then manufacturing process is simplified, but seal reliability deteriorates during actuation
Solution Approach 1:
The patent applies local quality by assigning different materials to different seal locations based on their specific functional requirements. The primary seal uses resin material optimized for sliding contact with the cylinder bore, while the secondary seal uses rubber material for additional sealing. This differentiated material selection ensures reliable seal contact during actuation while maintaining reasonable structural complexity.
3Device complexity
If the piston assembly uses simple seal configuration, then device complexity is reduced, but sliding performance deteriorates
Solution Approach 1:
The patent implements a composite seal configuration with a primary seal made of resin material and a secondary seal made of rubber material arranged on the piston body. This dual-seal configuration maintains reliable contact with the cylinder bore during actuation, improving sliding performance while keeping the device complexity at an acceptable level through systematic material selection.
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 sliding performance and maintains reliable seal contact within the cylinder bore, reducing manufacturing costs while ensuring efficient operation of hydraulic systems in human-powered vehicles.
Implementation Method 1
a coil spring biasing mechanism to ensure consistent contact with the cylinder bore
Data Source
AI summary
A piston assembly is provided for a human-powered vehicle. The piston assembly includes a main body, a primary seal and a secondary seal. The main body is configured to be movable from a rest position to an actuated position along an actuation direction in a cylinder bore. The primary seal includes a primary seal body arranged on the main body, the primary seal body being made of the first seal material. The secondary seal includes a secondary seal body arranged on the main body at upstream of the primary seal with respect to the actuation direction. The secondary seal body is made of a second seal material that is more elastic than the first seal material.