Spring Brake Actuator Diaphragm Sealing Design
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Solution Overview
Problem
Pneumatic brake systems face issues with leakage across the diaphragm's outer flange due to uneven compression and small sealing points, leading to sealing problems and difficulties in diaphragm replacement, especially in confined and space-constrained vehicle locations.
Innovation Solution
A cup-shaped diaphragm with offset sections and a wedge-shaped outer perimeter is designed to improve sealing by centering itself within the actuator and resisting pull-out, eliminating the need for a clamping band and allowing for easier replacement without removing the non-pressure plate portion from the vehicle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clamping ring is used to hold housing flanges together, then the diaphragm is secured in place, but uneven compression occurs at the clamp band's clamping bolt location causing leakage
Solution Approach 1:
The invention removes the clamping ring from the assembly, eliminating the source of uneven compression and leakage. The diaphragm is instead secured through its offset outer flange configuration that engages with the housing flanges directly, allowing for uniform compression without localized stress concentrations at clamp bolt locations.
Solution Approach 2:
Rather than using an external clamping ring to secure the diaphragm, the invention inverts the approach by designing the diaphragm's outer flange itself to provide the securing mechanism. The offset configuration of the outer flange creates engagement surfaces that hold the diaphragm in place without requiring additional clamping components.
2Ease of manufacture
If a wedge-shaped outer flange with small sealing points is used, then the diaphragm can be captured between flanges, but sealing problems occur and replacement becomes difficult
Solution Approach 1:
The invention adds dimensional complexity to the outer flange by creating offset sections that extend perpendicular to the central axis. This multi-dimensional configuration provides extended sealing surfaces and multiple contact points with the housing flanges, transforming a simple wedge shape into a complex geometric form that ensures uniform sealing across the entire diaphragm perimeter.
Solution Approach 2:
The offset sections of the outer flange create localized sealing zones with enhanced contact area. Each offset section provides a specific sealing region that distributes compression forces uniformly, ensuring high-quality sealing at critical locations rather than relying on small sealing points.
3Stability of the object's composition
If the diaphragm is secured with a clamping band, then the diaphragm is held in place, but leakage occurs due to uneven compression at bolt locations
Solution Approach 1:
The clamping band is completely removed from the assembly. The diaphragm positioning stability is achieved through the offset outer flange configuration that engages with the housing flanges, eliminating the need for external clamping components that cause uneven compression and sealing failures.
Solution Approach 2:
The diaphragm's offset outer flange design provides self-centering and self-positioning capabilities. The geometric configuration of the offset sections creates natural engagement surfaces with the housing flanges, allowing the diaphragm to secure itself in the correct position without requiring external clamping mechanisms.
Data Source
AI summary
A brake actuator is provided, in which a diaphragm, used in conjunction with a piston which compresses a parking brake-actuating spring, is arranged such that its outer peripheral region is captured between opposing housing flange portions such that a seal between the interior and exterior of the brake actuator housing is provided in a radially-oriented region of the diaphragm and the housing flange portions away from housing portion jointing components such as a clamp ring or individual fasteners. The diaphragm may also be provided with a wedge-shaped portion at its outer periphery which is axially oriented and configured to reside in a corresponding annular gap between the opposing housing flange portions.