Non-Circular Brake Piston for Higher Force in Compact Calipers
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Solution Overview
Problem
Hydraulic brake calipers for bicycles face challenges in providing sufficient braking force without increasing the size and weight, which affects performance and cost, especially when riders encounter higher speeds and steeper terrain.
Innovation Solution
The design incorporates a non-circular piston with a power elongation ratio greater than or equal to 1.5, which increases the hydraulic advantage within a smaller envelope size, and a seal that reduces the biasing force applied during braking, allowing for enhanced performance without additional materials or weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the number and/or size of caliper pistons are increased to provide greater braking force, then braking force is improved, but the overall size and weight of the caliper increase
Solution Approach 1:
The piston cross-section is designed with an asymmetric non-circular shape, specifically an oval shape with a major axis perpendicular to the minor axis. This asymmetric geometry increases the hydraulic advantage ratio while maintaining a compact overall piston size, thereby providing greater braking force without increasing caliper weight.
Solution Approach 2:
The invention changes the geometric parameters of the piston from a conventional circular cross-section to a non-circular oval cross-section. This parameter change optimizes the surface area-to-perimeter ratio, increasing hydraulic advantage while controlling the envelope size and weight of the caliper assembly.
2Force
If the number and/or size of caliper pistons are increased to provide greater braking force, then braking force is improved, but the overall size of the caliper increases
Solution Approach 1:
The oval-shaped piston cross-section with asymmetric dimensions (major axis perpendicular to minor axis) maximizes the hydraulic surface area within a compact envelope. This asymmetric geometry provides greater braking force while minimizing the overall caliper size and aerodynamic drag.
Solution Approach 2:
The invention transitions from a conventional circular piston (isotropic in all dimensions) to a non-circular oval piston that exploits different dimensional proportions. The major and minor axes create an optimized dimensional distribution that increases hydraulic advantage without proportionally increasing the caliper's overall footprint.
3Device complexity
If a conventional circular piston is used, then the caliper structure is simple, but the hydraulic advantage is limited
Solution Approach 1:
The piston cross-section employs asymmetric oval geometry with a major axis perpendicular to the minor axis, creating unequal dimensional proportions that optimize hydraulic advantage. This asymmetric design provides superior power transmission compared to symmetric circular pistons while maintaining relatively simple manufacturing processes.
Solution Approach 2:
The invention modifies the geometric parameters of the piston from a conventional circular cross-section to a non-circular oval cross-section. This parameter change optimizes the surface area-to-perimeter ratio, increasing hydraulic advantage while the structure remains sufficiently simple for practical manufacturing and assembly.
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 braking force while maintaining a compact and lightweight caliper, improving performance and reducing user input force required for braking, thus addressing the need for increased braking power without increasing size or weight.
Implementation Method 1
a seal disposed between an outer periphery of the brake piston and an interior surface of the cavity. The seal provides a biasing force to the brake piston.
Implementation Method 2
Hydraulic brake calipers may include one or more pistons that move one or more brake pads toward a brake rotor
Data Source
AI summary
A brake caliper includes a caliper housing having a first cavity. A piston is reciprocally moveable in the cavity. The piston is configured with a non-circular outer periphery defining a cross-sectional area orthogonal to the first axis. A portion of the outer periphery may be defined by a linear portion. The outer periphery may be disposed within an outer periphery of a brake pad coupled to the piston when the outer periphery of the piston is superimposed on a cross-sectional area of the brake pad.