Brake Caliper Piston Roll-Back Control via Friction Scraper
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Solution Overview
Problem
Existing devices for controlling piston roll-back in brake callipers exhibit variability due to temperature changes and construction tolerances, leading to inconsistent operation.
Innovation Solution
A device comprising a piston with a scraper element and elastic means, where the scraper element provides resistance to piston movement and the elastic means ensure repeatable piston return, with the scraper element's friction action being stronger than the elastic action, preventing deformation and ensuring consistent operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gasket is used as a roll-back element that deforms axially during piston movement, then the piston can be returned into the cylinder after braking, but the operation exhibits variability due to temperature changes and construction tolerances
Solution Approach 1:
The invention changes the physical state of the scraper element from deformable (like traditional gaskets) to rigid or substantially non-deformable. This parameter change eliminates the variability caused by temperature and construction tolerances that affect elastomeric gaskets, providing consistent friction-based resistance to piston movement across all operating conditions.
Solution Approach 2:
The invention replaces the elastic deformation mechanism of traditional gaskets with a friction-based mechanical resistance system. The scraper element provides controlled friction resistance through its rigid structure, substituting the unreliable elastic recovery mechanism with a predictable friction-based system that is insensitive to temperature and tolerance variations.
2Ease of operation
If the scraper element allows substantial axial deformation, then it can accommodate piston movement, but it cannot provide consistent resistance and control roll-back
Solution Approach 1:
The invention changes the deformation parameter of the scraper element from substantial (allowing free piston movement) to substantially prevented (rigid structure). This creates a controlled friction interface that provides consistent resistance to piston movement while still allowing the necessary range of motion through the friction mechanism rather than deformation.
Solution Approach 2:
The scraper element acts as an intermediary between the piston and the cylinder wall, providing controlled friction-based resistance. This intermediary mechanism allows piston movement while maintaining consistent control over roll-back, mediating between the need for movement accommodation and the need for reliable control.
3Ease of operation
If the elastic action is stronger than the friction action, then the piston returns easily, but the scraper element deforms and cannot provide controlled resistance
Solution Approach 1:
The invention changes the strength parameter of the scraper element from deformable (where elastic action exceeds friction action) to rigid (where friction action dominates). This parameter change ensures that the friction-based resistance mechanism controls the piston return process, providing precise control over roll-back while preventing unwanted deformation of the scraper element.
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
The solution achieves repeatable and controlled piston roll-back, maintaining operational consistency across varying conditions, including temperature changes and construction tolerances, while allowing for precise adjustment of the roll-back extent.
Implementation Method 1
Elastic means are provided between the bush and the piston body and are suitable for elastically and axially influencing the bush and the piston body in reciprocal moving apart. When stressed by the movement of the piston, the elastic means are suitable for elastically yielding up to packing
Implementation Method 2
A scraper element is seated in a seat provided in the calliper body so as to act pressure-wise against a sealing surface of the piston. The scraper element provides resistance to piston movement with its friction action being stronger than the elastic action
Data Source
AI summary
A device for controlling roll-back of a piston in a brake caliper includes a bush coaxial with and external to the piston. The bush has an outer sealing surface, and a scraper element seated in the caliper body acts against the sealing surface of the bush. An elastic element between the bush and the piston has a elastic constant selected so as to provide an elastic force on the piston substantially weaker that the axial friction force exerted by the scraper element. When the piston is pushed out of its piston seat, the piston packs the elastic means or abuts against the bush before relative sliding occurs between the scraper element and the outer sealing surface of the bush.