Nested Boot Structure for Compact Brake Actuators
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Solution Overview
Problem
Existing brake actuators for commercial vehicles are limited by the size of dust shields, which restrict the length of the push-rod, leading to increased overall size and potential contamination issues due to the fixed effective length of the boot in the actuated state.
Innovation Solution
A brake actuator design featuring a boot with a larger cross-sectional area at the distal end section compared to the maximum cross-sectional area of its segments, allowing for overlapping and reducing the effective length, thus enabling a shorter push-rod and a smaller second chamber, while maintaining dust protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a traditional dust shield with constant effective diameter is used, then dust protection is provided, but the effective length of the boot increases, limiting the push-rod length reduction
Solution Approach 1:
The boot segments are designed to nest within each other in the actuated state, with each segment having a progressively smaller outer diameter than the previous segment. This nesting configuration allows the boot to maintain dust protection while significantly reducing its effective length when the push-rod is actuated, thereby enabling shorter push-rod stroke and compact actuator design.
Solution Approach 2:
The boot is divided into multiple segments along its length, with each segment having a different outer diameter. The segments are arranged such that their cross-sectional areas decrease from the proximal end to the distal end, allowing them to overlap and nest within each other during actuation. This segmentation enables the boot to provide continuous dust protection while reducing its overall effective length in the actuated state.
2Volume of moving object
If the push-rod length is reduced to decrease actuator size, then compactness is improved, but the boot must be redesigned to accommodate the shorter stroke
Solution Approach 1:
The nested doll principle is applied to the boot structure, where segments of decreasing diameter are arranged to nest within each other during actuation. This allows the boot to accommodate a shorter push-rod stroke while maintaining its dust sealing function, thereby enabling compact actuator design without excessive complexity.
Solution Approach 2:
The boot structure transitions from a static, constant-diameter design to a dynamic, variable-diameter design where segments can overlap and nest during actuation. This dynamic configuration allows the boot to adapt its effective length to match the reduced push-rod stroke while maintaining sealing effectiveness throughout the motion range.
3Volume of stationary object
If the second chamber volume is reduced to accommodate limited space, then space utilization is improved, but the push-rod aperture and boot configuration must be optimized
Solution Approach 1:
The nested boot segments allow for a more compact arrangement within the second chamber, enabling reduced chamber volume while maintaining adequate space for the boot's dust sealing function and the push-rod's motion. The nesting configuration optimizes the use of available space in the constrained environment.
Solution Approach 2:
The boot segments are designed with varying local properties, specifically decreasing outer diameters from proximal to distal segments. This local quality variation allows the boot to occupy less overall volume in the second chamber while maintaining its sealing function at each location along the push-rod stroke.
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
This configuration allows for a reduced overall size of the brake actuator, accommodating limited space in pneumatic systems while effectively shielding the push-rod from contaminants, enhancing the actuator's compactness and functionality.
Implementation Method 1
The boot has at least one foldable boot segment in a longitudinal direction. A cross-sectional area amount of the boot inner volume at the distal end section of the boot is larger than a maximum cross-sectional segment area of a first boot segment proximate the distal end section such that, in a folded state of the boot, the first boot segment is at least partially fitted inside the distal end section
Implementation Method 2
The first chamber and the second chamber are separated by a movable separation element arranged at the housing, such that a volume amount of the first chamber increases, and a volume amount of the second chamber decreases, when the fluid, in particular the compressed air, enters the first chamber via the inlet and actuates the separation element
Data Source
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AI summary
The invention is directed to a brake actuator (100), comprising a housing (102) with an inlet port (1) for receiving a fluid, and a push-rod aperture (104), and configured to accommodate a first chamber (106) connected to the inlet port and a second chamber (108) that includes the push-rod aperture. The first chamber and the second chamber are separated by a movable separation element (110) to which a push-rod (112) is connected that protrudes outside the housing via the push-rod aperture. A boot (114) defining an inner volume (V3) has a proximal end section (114a) connected to the push-rod and a distal end section (114b) connected to the housing, wherein a cross-sectional area amount (A1) of the inner volume at the distal end section is larger than a cross-sectional segment area (A2) of a boot segment (116), thus enabling a reduction of a length of the push rod.