Piston Seal with Isolated Pressure Insert for Low-Temperature Flexibility
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Solution Overview
Problem
Existing sealing devices for piston pumps in hydraulic and brake systems face challenges with flexibility at low temperatures, wear resistance, and uniform sealing performance, especially under high radial play and negative pressure conditions, due to direct contact with the medium and non-uniform force transmission.
Innovation Solution
A sealing device design where a pressure insert, made of a flexible material like silicone, is positioned away from the sealing element, allowing only the sealing element to contact the medium, and is connected to both static and dynamic sealing parts, with separate manufacturing and cohesive connection, ensuring the pressure insert does not come into direct contact with the fluid and providing enhanced sealing through an L-shaped configuration and axial pressure lip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a metal snap ring is used as a prestressing element, then the sealing element is pressed against the piston surface, but the radial force transmission is non-uniform causing non-uniform abrasion and early leakage
Solution Approach 1:
The prestressing element is designed with non-uniform cross-sectional thickness, where the thickness varies along the circumferential direction. This creates different prestressing forces at different locations, compensating for non-uniform wear and radial play, thereby achieving more uniform contact pressure distribution across the sealing surface.
Solution Approach 2:
The cross-sectional dimensions of the prestressing element are specifically designed to vary, with the thickness changing along the circumference. This parameter variation allows the prestressing element to adapt to radial play and wear patterns, maintaining uniform sealing pressure despite piston movement and wear over time.
2Reliability
If both sealing element and prestressing elements contact the liquid medium, then sealing is achieved, but media resistance requirements increase and material selection is limited
Solution Approach 1:
The sealing system is divided into two functional parts: the sealing element that contacts the medium and the prestressing element that provides mechanical force. This segmentation allows each component to be optimized independently - the sealing element for media resistance and the prestressing element for mechanical properties.
Solution Approach 2:
The prestressing function is extracted from the sealing element and implemented as a separate prestressing element. This allows the prestressing element to be made from materials optimized for mechanical performance rather than media resistance, expanding material selection flexibility.
3Duration of action of moving object
If the piston has radial play for longer running times, then wear of radial piston guides increases causing increased radial play, but sealing performance deteriorates
Solution Approach 1:
The prestressing element is designed to accommodate radial play and piston movement dynamically. Its flexible construction allows it to maintain continuous contact and prestress force despite piston displacement and radial clearance variations, ensuring consistent sealing performance throughout the service life.
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 solution provides improved flexibility at low temperatures, reduced wear, and enhanced sealing performance across a wide temperature range, preventing air ingress and medium leakage, even with high radial play, while maintaining a simple design and easy assembly.
Implementation Method 1
The pressure insert (3) is made from a material which has a particularly high degree of flexibility even at low temperatures. Here, a silicone can be used as the material.
Implementation Method 2
The sealing parts of the sealing element (2) each have at least one sealing lip. The sealing lips rest against the piston surface (15).
Data Source
Figure 1~2
AI summary
The seal device (1) has a seal element (2) with a pressure insert (3) fixed at a radial static seal part (7) and a radial dynamic seal part (11) of the seal element. The pressure insert is arranged at a side of the seal element, where the side is turned away from a medium (M). The seal element and the pressure insert are made of different materials, where the pressure insert is connected with the seal element in a form-fit manner. The seal element has an axial pressure lip at a medium side, where the pressing lip is attached at a base of a retainer (4) for the seal device.