Brake Guide Bar Reduced Diameter for Bellows Air Pressure Equalization
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Solution Overview
Problem
The existing guide bars for disc brake thrust bearings do not effectively manage air pressure equalization during rapid relative movements between the brake carrier and caliper, leading to potential damage or leaks due to trapped air, especially during complete compression, which can result in loose fasteners and compromised operational reliability.
Innovation Solution
A guide bar with varying diameters, featuring a reduced diameter longitudinal section covered by the fold section and a secondary seal, allows for air pressure equalization and prevents damage by ensuring air can escape, while maintaining structural simplicity and existing manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bellows is completely compressed during assembly or operation, then the inner edges of the folds have minimal diameter and minimal distance to the guide bar, but air trapped in the bellows cannot escape quickly enough causing the bellows to bloat and potentially damage fasteners
Solution Approach 1:
The guide bar is pre-formed with a reduced-diameter longitudinal section at the position where the bellows will be completely compressed. This preliminary structural feature ensures that when the bellows is compressed during assembly or operation, there is always sufficient radial clearance between the inner edges of the folds and the guide bar, allowing trapped air to escape and preventing pressure buildup that could damage fasteners or compromise the bellows.
Solution Approach 2:
The guide bar features a localized reduction in diameter specifically in the longitudinal section that corresponds to the compressed position of the bellows. This local geometric modification creates additional radial space exactly where needed - when the bellows folds are compressed - without affecting the overall dimensions or functionality of the guide bar in other regions. The reduced diameter section provides the necessary clearance for air escape paths.
2Strength
If the annular groove diameter is significantly smaller than the bearing section diameter to ensure form-fit for the bellows bead, then the bellows is securely fixed, but the guide bar structure becomes more complex
Solution Approach 1:
The annular groove for fixing the bellows bead and the reduced-diameter longitudinal section are merged into a single integrated geometric feature of the guide bar. The groove is formed as part of the reduced-diameter section, eliminating the need for separate structural elements. This combination maintains secure bellows fixation through the form-fit groove while avoiding additional complexity, as both functions are achieved through one continuous geometric modification of the guide bar.
Solution Approach 2:
The reduced-diameter longitudinal section serves multiple functions simultaneously: it provides the annular groove for securing the bellows bead through form-fit, maintains the necessary radial clearance for air escape during compression, and preserves the structural integrity of the guide bar. This multi-functional design eliminates the need for separate features, reducing overall device complexity while achieving multiple objectives.
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 ensures the bellows can function without restriction, preventing damage and ensuring operational reliability by allowing air to escape during maximum compression, thus preventing bloat and potential leaks.
Implementation Method 1
pressure equalization in the volume of air enclosed by the bellows is made possible
Implementation Method 2
the amount of air trapped in the bellows can be compensated for when the bellows is slowly stretched or compressed
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
The brake has a disk brake caliper supported to a brake carrier by an axial bearing. The bearing has a guide bar (10) with a cylindrical bearing section (14), where the guide bar is surrounded by a bellows (25) for sealing the axial bearing. A fold section (35) of the bellows is changed between a compressed length and an elongated length. The guide bar exhibits a diameter (D2) on a longitudinal section (40) that is partially covered by the compressed length of the fold section, where the diameter is smaller than another diameter (D1) on the cylindrical bearing section.