Master Cylinder Stop Cap Design for Axial Space Reduction
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Solution Overview
Problem
Existing master cylinder designs require significant installation space and complex tooling due to the need for thick housing components and retaining clips, leading to assembly challenges and potential quality issues from burrs.
Innovation Solution
A master cylinder design featuring a stop cap with an opening that limits piston rod mobility, connected to the housing via a materially bonded or form-fitting mechanism, allowing for a spatially separated stop function that reduces axial installation space and simplifies assembly, using a bayonet connection or welding for secure fastening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a retaining clip connection is used to fix the piston rod, then the piston rod can be secured in the housing, but the axial installation space increases and the housing tooling becomes more complex
Solution Approach 1:
The stop function is moved from the interior of the housing to the exterior, allowing the stop cap to be positioned at the end of the housing where it does not consume axial space within the housing bore. The stop cap protrudes axially but the stopping action occurs outside the housing interior, effectively decoupling the stop function from the housing length.
Solution Approach 2:
The housing is divided into two functional parts: the housing proper that contains the hydraulic components, and the stop cap that provides the stopping function. This segmentation allows the stop cap to be designed independently and positioned where it does not interfere with the housing interior space requirements.
2Reliability
If a retaining clip connection is used to fix the piston rod, then the piston rod can be secured in the housing, but the housing tooling becomes more complex and burrs form during assembly
Solution Approach 1:
The stop function is merged with the housing end cap structure. The stop cap is integrally formed or closely coupled with the housing end, eliminating the need for separate retaining clips and their associated complex tooling for forming retaining lugs or recesses within the housing interior.
Solution Approach 2:
The stop function is extracted from the housing interior and placed in a separate stop cap component. This eliminates the need for complex internal housing features such as retaining lugs, recesses, or grooves that would require sophisticated injection molding tools or secondary operations.
3Strength
If thick housing wall thickness is used to ensure master cylinder strength, then structural strength is maintained, but axial installation space increases
Solution Approach 1:
The stop function is relocated to the exterior of the housing, allowing thin-walled housing construction without compromising the stopping capability. The stop cap provides the necessary stopping force from the exterior, eliminating the need for thick housing walls to accommodate internal stopping mechanisms.
Data Source
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AI summary
The invention relates to a master cylinder, in particular for a hydraulic actuation system of a friction clutch, in particular in a vehicle powered by an internal combustion engine, comprising a cylinder (201) having a piston (202) with a piston rod, which piston can be moved in a housing (204) in a direction of movement (205), wherein a stop cap (207) is provided, wherein the stop cap has an opening through which the piston rod can be moved. The stop cap is connected externally to the housing and the mobility of the piston rod is limited in a direction of movement. The master cylinder according to the invention advantageously enables the piston rod to be mounted in a simple manner in the housing combined with the formation of a corresponding stop region. Compared with known solutions, the master cylinder can be made shorter in the direction of movement since the insertion of a retaining clip and a corresponding elongation of the housing on strength grounds are unnecessary.