Brake Caliper Bellow with Folding Aid Rib
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Solution Overview
Problem
Conventional sealing bellows for motor vehicle disc brake caliper pistons tend to twist and tear when retracted, losing their sealing effectiveness due to undulations in the penultimate ply during brake pad replacement, leading to compromised resistance and functionality.
Innovation Solution
Incorporation of folding aid means, including axial reinforcing elements and abutment elements made from elastomeric material, distributed around the periphery to prevent deformation and tearing, ensuring the bellows can maintain its sealing role during the transition from deployed to retracted positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bellows are used during brake pad replacement, then the bellows can be installed and initially function, but the penultimate ply deforms by undulating causing twisting and tearing that compromises sealing effectiveness
Solution Approach 1:
The bellows is pre-formed with pleats during manufacturing that are designed to fold neatly during retraction. This preliminary structuring prevents the penultimate ply from undulating and twisting when the bellows is compressed during brake pad replacement, thereby maintaining sealing effectiveness and preventing tearing
Solution Approach 2:
The bellows utilizes elastomeric material properties that allow it to deform elastically during installation and operation, then return to its original shape. The material parameters are selected to provide sufficient flexibility for installation while maintaining structural integrity during retraction cycles
2Adaptability or versatility
If the bellows is made flexible to accommodate piston movement, then it can protect the piston surface, but it becomes prone to twisting and tearing during retraction
Solution Approach 1:
The bellows is divided into multiple discrete pleats or folds rather than being a continuous flexible wall. This segmentation allows each pleat to fold independently and predictably during retraction, preventing the material from twisting and tearing while still maintaining the flexibility needed to accommodate piston movement
Solution Approach 2:
The bellows employs curved pleat geometries that are optimized to fold along predetermined paths. The curved shapes distribute stress evenly during compression and retraction, preventing stress concentration points that would lead to tearing while maintaining the necessary flexibility for piston movement
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 effectively prevents deformation and tearing of the bellows, maintaining its sealing effectiveness and extending its lifespan by ensuring smooth folding and rotation, thereby reducing the risk of failure during brake pad replacement.
Implementation Method 1
the elastomeric material of the bellows
Data Source
Figure 1~3
Figure 4~5
Figure 6~8
AI summary
The boot (10) has an exterior ply (22) whose free end (24) is fixed to an internal wall of an annular groove of a piston, an intermediate ply (28), a penultimate ply (30), and an interior last ply (32) whose free end (34) received in the groove, where the boot is movable between retracted and deployed positions. The penultimate ply has a folding assistance unit (38) for avoiding deformation of the penultimate ply when the boot passes from the deployed position to the retracted position and having a longitudinal rib (42) contacting with an elastomer material of the boot.