Nested Brake Cylinder Layout to Cut Air Use and Parking Brake Interference
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Solution Overview
Problem
Existing combined service brake and spring brake cylinders for commercial vehicles face challenges such as increased installation space requirements and interference between service brake and spring brake functions, leading to inefficiencies in compressed air consumption and parking brake force.
Innovation Solution
A compact design for a combined service brake and spring brake cylinder is achieved by arranging the service brake cylinder radially inside the spring brake cylinder, with the service brake piston guided directly on the inner surface of the service brake cylinder or assisted by a diaphragm. This configuration minimizes interference between the two brake functions and allows for a larger effective area for the spring brake piston.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the service brake cylinder and spring brake cylinder are arranged coaxially one behind the other, then the brake system can be compact, but the installation space within the wheel arches becomes too long
Solution Approach 1:
The service brake cylinder is nested inside the spring brake cylinder, with the service brake piston rod passing through the spring brake piston. This nesting arrangement allows both brake systems to occupy the same radial space, dramatically reducing the axial installation length while maintaining both braking functions.
2Device complexity
If the service brake piston is guided within the spring brake piston with a radially inwardly extending peripheral edge, then the brake system can be integrated, but the spring brake piston is loaded by service brake pressure generating unwanted forces
Solution Approach 1:
The service brake piston is extracted from the spring brake piston structure and guided independently on the inner circumferential surface of the spring brake cylinder. This separation eliminates the harmful interaction where service brake pressure would load the spring brake piston, while maintaining compact integration.
Solution Approach 2:
A guide structure on the spring brake cylinder inner surface serves as an intermediary element that guides the service brake piston independently, preventing direct harmful contact between the service brake pressure and the spring brake piston while maintaining structural integration.
3Device complexity
If the effective area of the spring brake piston is reduced to accommodate the service brake piston, then the brake system can be integrated, but the parking brake release pressure becomes too high or the spring stiffness too low
Solution Approach 1:
The service brake cylinder is nested within the spring brake cylinder, allowing the spring brake piston to maintain its full effective area for parking brake release pressure while the service brake components occupy the central radial space. This nesting preserves the hydraulic effectiveness of the spring brake system.
Solution Approach 2:
The service brake piston operates in the radial dimension inside the spring brake cylinder, while the spring brake piston maintains its full axial effective area. This dimensional arrangement allows both systems to function independently without compromising the spring brake's pressure-generating capability.
4Device complexity
If the service brake chamber and spring brake chamber are connected through a common piston rod, then both brakes can be actuated through the same mechanism, but dirt and air can flow between chambers affecting brake function
Solution Approach 1:
The service brake piston is extracted from the spring brake piston structure and given its own independent guiding mechanism on the spring brake cylinder inner surface. This separation ensures that the service brake chamber and spring brake chamber remain hydraulically independent, preventing contamination while allowing both to be actuated through their respective pressure sources.
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 proposed design reduces compressed air consumption and enhances the parking brake force by minimizing the influence of service brake pressure on the spring brake piston and increasing the effective area for the parking brake release pressure, thereby improving the overall efficiency and reliability of the brake system.
Implementation Method 1
a spring brake piston and at least one accumulator spring loading the spring brake piston in an application direction of the parking brake
Implementation Method 2
the spring brake piston and the spring brake cylinder delimiting a spring brake chamber which can be pressurized by a parking brake release pressure
Data Source
Figure 1~2
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Figure 4
AI summary
The invention relates to a combined service brake and spring brake cylinder (1) for operating a service brake and a parking brake, comprising: A spring brake cylinder (4), a spring brake piston (10) and at least one accumulator spring (3) loading the spring brake piston (10) in a parking brake application direction, a service brake cylinder (6) and a service brake piston (18), the service brake cylinder (6) and the service brake piston (18) delimiting a service brake chamber (19) which can be pressurized and vented with a service brake pressure, the service brake cylinder (6), viewed radially, being arranged inside the spring brake cylinder (4). It is provided that the service brake piston (18) is displaceably guided directly on a radially inner circumferential surface of the service brake cylinder (6), or in that a diaphragm cooperating with the service brake piston (18) is fastened to the service brake cylinder (6) and/or to the spring brake cylinder (4).