Cylinder Cup Seal With Tapered Base For Stable Sealing
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Solution Overview
Problem
The existing cylinder apparatuses with cup seals face issues in maintaining effective sealing force and stabilizing the ineffective stroke due to the annular protruding portion being bitten into the piston passage hole and the tapered surface not being adequately pressed during hydraulic fluid pressurization, leading to unstable operation.
Innovation Solution
The cylinder apparatus incorporates a cup seal with an abutment portion that protrudes towards the cylinder bore opening and a contact pressure adjustment portion on the base end surface, which is non-contact in the non-operational state but contacts the opening-side-surface during operation, optimizing the contact pressure between the inner circumferential surface of the base portion and the piston, and includes a conical surface intersecting the cylinder bore at an acute angle for enhanced deformation and sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an annular protruding portion is formed on the inner circumference of the base portion to improve sealing property, then sealing force is improved, but the protruding portion is bitten into the piston passage hole when the piston operation is started
Solution Approach 1:
The patent applies preliminary action by providing a tapered surface on the inner circumference of the base portion that becomes wider toward the outer diameter side. This tapered surface is prepared in advance to prevent the annular protruding portion from being bitten into the piston passage hole when the piston operation starts, while still maintaining the sealing function during normal operation.
2Object-affected harmful factors
If a tapered surface is provided on the inner circumference of the base portion to prevent biting into the piston, then the biting problem is solved, but the tapered surface is not brought into pressure contact with the piston during hydraulic fluid pressurization, causing unstable ineffective stroke
Solution Approach 1:
The patent applies local quality by differentiating the functions of different portions of the base portion. The tapered surface on the inner circumference prevents biting into the piston, while a separate annular protruding portion is provided that can be pressed against the piston during hydraulic fluid pressurization to maintain stable sealing and ineffective stroke. Each portion has optimized local properties for its specific function.
3Reliability
If the contact pressure between the base end surface and opening-side-surface is increased to improve sealing, then sealing force is improved, but the base portion is made less likely to extend in the radial direction, reducing sealing effectiveness
Solution Approach 1:
The patent applies segmentation by dividing the sealing function into multiple components: the base end surface contacts the opening-side-surface to prevent axial leakage, while the annular protruding portion contacts the piston to provide radial sealing. This segmentation allows each component to be optimized independently, maintaining sealing effectiveness without requiring excessive contact pressure that would prevent base portion extension.
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 ensures reliable sealing force and stabilizes the ineffective stroke, providing excellent operation feeling and reliable brake control in hydraulic pressure master cylinders, especially in vehicle brake systems, by optimizing the deformation of the base portion and reducing sliding resistance.
Implementation Method 1
the inner circumferential surface of the base portion is smoothly pressed against the outer circumferential surface of the piston when the cylinder apparatus is actuated and hydraulic fluid in a hydraulic pressure chamber starts to be pressurized
Implementation Method 2
a conical surface intersecting the cylinder bore at an acute angle for enhanced deformation and sealing
Implementation Method 3
reducing sliding resistance
Data Source
AI summary
A cup seal includes a base portion disposed on a cylinder bore opening portion side of a seal groove, an inner circumferential lip portion extended from an inner circumferential side of the base portion toward a cylinder bore bottom portion and having an inner circumferential surface slidably abutting against an outer circumferential surface of a piston (plunger), and an outer circumferential lip portion extended from an outer circumferential side of the base portion toward the cylinder bore bottom portion and having an outer circumferential surface abutting against a seal groove bottom surface. The cup seal also includes an abutment surface and contact pressure adjustment surface.