Spring Brake Actuator Diaphragm Sealing for Pressure Leakage
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Solution Overview
Problem
Existing spring brake actuators for commercial vehicles face challenges with pressure leakage due to the sliding movement of sealing members, requiring precise installation and close tolerances, and are prone to dirt accumulation from removable release bolts.
Innovation Solution
Incorporating an elastically deformable diaphragm with an annular flange sealingly mounted to the cylinder housing and spring brake piston, along with a permanently installed release bolt and static nut, to create a fluid-tight separation between the spring and pressure chambers, preventing relative movement and ensuring easy installation and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a sliding sealing member is used on the spring brake piston, then the brake actuator can function with simple structure, but pressure loss occurs due to sliding movement and close tolerances are required during installation
Solution Approach 1:
The patent replaces the sliding sealing member with a diaphragm made of flexible material that forms a fluid-tight seal between the spring chamber and pressure chamber. The diaphragm flexes to accommodate piston movement without sliding, eliminating pressure loss while maintaining simple structure.
Solution Approach 2:
The patent substitutes the mechanical sliding seal with a flexible membrane seal. Instead of relying on friction and tight tolerances between sliding surfaces, the diaphragm creates a flexible barrier that maintains sealing through its elastic properties, replacing the mechanical sliding contact system.
2Ease of operation
If a removable release bolt is used, then maintenance and installation are flexible, but dirt accumulation occurs inside the cylinder housing
Solution Approach 1:
The patent designs the release bolt to be permanently installed with a dust-proof cover that integrates the sealing function. The system serves itself by maintaining a closed environment without requiring separate dust plugs or frequent opening for maintenance, preventing dirt accumulation while allowing necessary operations.
Solution Approach 2:
The patent introduces a dust-proof cover as an intermediary element between the release bolt and the environment. This cover allows the release bolt to remain permanently installed for maintenance flexibility while preventing dirt from entering the cylinder housing, mediating between the need for accessibility and contamination prevention.
3Force
If the spring brake piston has large travel, then the brake force transmission is effective, but installing a diaphragm between chambers becomes unfeasible
Solution Approach 1:
The patent resolves the installation feasibility issue by designing the diaphragm to accommodate the full piston travel range. The diaphragm is positioned and dimensioned to allow the piston to move through its entire stroke while maintaining sealing, effectively adding the dimension of travel accommodation to the sealing solution.
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 reduces pressure leakage risks and maintains a sealed environment, eliminating the need for additional dust plugs and simplifying maintenance by using a permanently installed release bolt and static nut, while ensuring reliable sealing and ease of assembly.
Implementation Method 1
a compression spring arranged between the spring seat and the spring brake piston, the compression spring being effective to push the spring brake piston away from the base
Implementation Method 2
the cylinder housing comprises an elastically deformable diaphragm that comprises an annular flange which is sealingly mounted to the cylinder housing, and an inner periphery which is sealingly mounted to the spring brake piston
Data Source
AI summary
A spring brake actuator (1) for a vehicle, in particular a parking or emergency brake actuator, for use in a commercial vehicle, includes a cylinder housing (2) having a cylinder housing base (5) and a spring seat (7) on the base, a spring brake piston (9) located in the cylinder housing (5) for applying a braking force, and a compression spring (11) arranged between the spring seat (7) and the spring brake piston (9). The cylinder housing (2) is divided into a spring chamber (12) and a pressure chamber (14), the compression spring (11) being arranged in the spring chamber (12) and the pressure chamber (14) being supplied with pressurized fluid. An elastically deformable diaphragm (16) is sealingly mounted to the cylinder housing (2), with an inner periphery (18) sealingly mounted to the spring brake piston (9) to fluid-tightly isolate the pressure chamber (14) from the spring chamber (12).