Master Cylinder Sealing Element Positioning for Idle Stroke Reduction
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Solution Overview
Problem
Existing master cylinders require a significant idle stroke to build pressure in the cylinder chamber, which increases assembly complexity and reduces efficiency.
Innovation Solution
The sealing element is inserted into the cylinder housing through an outer opening with a bore that matches the groove's cross-sectional area, allowing for easy assembly and fixation, and the after-run space is positioned between the sealing element and the piston skirt surface to minimize the idle stroke by ensuring hydraulic medium flow during pressure equalization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing element is inserted through a narrow bore requiring deformation, then the sealing element can be fixed in the groove, but the assembly process becomes complex and time-consuming
Solution Approach 1:
Instead of inserting the sealing element through a narrow bore that requires deformation, the patent inverts the approach by providing a bore with a cross-sectional area that is equal to or larger than the groove base area. This allows the sealing element to be inserted in its original shape without deformation, significantly simplifying the assembly process while ensuring reliable fixation through the groove structure.
2Reliability
If the piston travels a considerable distance to build pressure, then pressure equalization can be achieved, but the idle stroke becomes large reducing efficiency
Solution Approach 1:
The patent positions the after-run space between the sealing element and the piston skirt surface, and places the overflow opening opposite an inner surface of the sealing element. This preliminary positioning ensures that hydraulic medium can flow directly into the cylinder chamber through the after-run space and overflow opening, enabling pressure equalization to occur with minimal piston travel and reducing the idle stroke.
3Ease of manufacture
If the bore cross-sectional area is made large to match the groove base, then the sealing element can be inserted easily, but the housing structure becomes more complex
Solution Approach 1:
The bore serving as an insertion path is designed with a cross-sectional area equal to or larger than the groove base area, allowing it to serve multiple functions: as a tool for inserting the sealing element in its original shape, as a structural feature of the housing, and as a pathway for hydraulic medium flow. This multi-functionality reduces the need for separate insertion tools or complex assembly mechanisms.
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 design minimizes the idle stroke, simplifies assembly, and ensures efficient pressure buildup in the cylinder chamber, enhancing the overall performance of the master cylinder.
Implementation Method 1
the overflow opening (108) is arranged opposite an inner surface (64) of the sealing element delimiting the after-run space in the pressure equalization position, in particular such that in the pressure equalization position hydraulic medium can flow into the cylinder chamber (18) for pressure equalization
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
In order to minimize the resulting free stroke in a master cylinder, particularly for a clutch, actuation, or braking system of a vehicle, comprising a cylinder housing with a piston bore, a piston arranged in the piston bore with an end face facing a cylinder chamber and with at least one overflow opening leading from a piston surface through a piston wall to the cylinder chamber at a distance from the end face, which in a pressure-equalizing position of the piston adjoins an overflow chamber so that hydraulic medium can flow into the cylinder chamber for pressure equalization in the pressure-equalizing position, and an internal sealing element arranged between the housing and the piston in the region of the piston bore and delimiting the cylinder chamber, it is proposed that the overflow chamber between the sealing element and the piston surface be arranged on a side of a sealing lip of the sealing element facing away from the cylinder chamber.