Elastic Seals for Pressure Equalization in Hydraulic Cylinders
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Solution Overview
Problem
Existing double-acting hydraulic working cylinders face challenges in pressure medium overflow between working chambers, particularly in end positions, due to spatial constraints and construction-related efforts, limiting their range of use.
Innovation Solution
The design incorporates a piston with first and second side disks and a central section, featuring annular elastic seals that deform differently based on pressure direction, allowing pressure equalization between working chambers through adjustable overflow cross-sections, eliminating the need for additional moving components and enabling reliable pressure medium transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spring-loaded valve bodies with tappets are used for pressure equalization, then pressure medium can be transferred between working chambers, but the device complexity increases and installation space is consumed
Solution Approach 1:
The invention extracts the pressure equalization function from complex mechanical valve components and transfers it to the sealing elements themselves. The sealing elements are designed to automatically open pressure equalization passages through their own deformation under pressure, eliminating the need for separate valve bodies, springs, and tappets that would increase device complexity and consume installation space.
Solution Approach 2:
The sealing elements perform dual functions: sealing the piston and automatically opening pressure equalization passages when needed. Under high pressure, the sealing elements deform to create openings in the piston, enabling pressure medium transfer without requiring external actuation mechanisms. This self-service approach simplifies the overall device structure.
2Reliability
If symmetric valve arrangements with tappets are used, then pressure equalization is achieved, but the cross-section for overflowing pressure medium is limited
Solution Approach 1:
The invention replaces static symmetric valve arrangements with dynamic sealing elements that automatically adapt their opening size based on pressure conditions. The sealing elements deform elastically under pressure, dynamically adjusting the overflow cross-section to match the actual pressure equalization needs, thereby maximizing the effective overflow area without requiring fixed mechanical valve structures.
Solution Approach 2:
The sealing elements change their physical state and geometry in response to pressure parameters. Under normal operating pressure, they maintain their sealing shape. When pressure differential exceeds a threshold, they deform to open passages, effectively changing the overflow cross-section parameter from small (sealed) to large (open), optimizing pressure medium transfer.
3Reliability
If additional moving components are added for pressure equalization, then pressure medium transfer is enabled, but construction-related effort and spatial constraints increase
Solution Approach 1:
The invention merges the sealing function and pressure equalization function into a single integrated component - the sealing element. Instead of having separate sealing rings and valve mechanisms, the sealing elements are designed with embedded pressure equalization passages that activate automatically, reducing the number of parts and simplifying manufacturing and assembly processes.
Solution Approach 2:
The sealing elements serve multiple functions simultaneously: they seal the piston to prevent leakage, guide piston movement, and automatically open pressure equalization passages when pressure differential requires it. This multi-functionality eliminates the need for dedicated pressure equalization components, reducing construction effort and spatial requirements.
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 solution enables efficient pressure equalization in both directions without additional mechanical components, ensuring reliable operation and easy maintenance, with adjustable pressure gradients and reduced notch stresses for long seal life.
Implementation Method 1
The piston has a first side disk and a second side disk and a central section between the first and second side disks as well as a first and a second annular elastic seal... Each of the seals can be deformed differently depending on the direction in which the pressure is applied and thus has a different sealing behavior depending on the direction of the pressure drop.
Implementation Method 2
pressure medium flows from one working chamber to the other... The pressure medium flows from one working chamber to the other through the deformed seals, equalizing pressure between chambers
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a working cylinder for pressure medium flow transfer between the working chambers of a double-acting hydraulic working cylinder in the vicinity of the end positions of the piston. A working cylinder according to the invention is characterised in that the piston (1) has a first and a second annular elastic seal (13; 14). The first annular elastic seal (13) is mounted against a first side plate (10) axially in the direction of a second side plate (11) and is supported on one side by the first side plate (10), the second annular elastic seal (14) is mounted against the second side plate (11) axially in the direction of the first side plate (10) and is supported on one side by the second side plate (11). Each of said annular elastic seals (13;14) is elastically deformable when pressure is applied in the direction of a central portion (12), forming a gap with respect to the cylinder tube inner wall (15). When pressure is applied in the opposite direction, the elastic deformation of the annular elastic seal (13, 14) is limited by the respective side plate (10; 11) and the annular elastic seal (13, 14) exerts a sealing force. The working cylinder is further characterised in that the cylinder tube (1) comprises a first and a second recess (20; 21), wherein the first recess (20) is arranged axially in such a way that only the first annular elastic seal (13) in a first end position of the piston (9) is positioned above the first recess (20) and by means of the first recess (20) a first flow transfer cross-section opens between the first annular elastic seal (13) and the cylinder tube (1), wherein the second recess (21) is arranged axially in such a way that only the second annular elastic seal (14) in a second end position of the piston (9) is positioned above the second recess (21) and by means of the second recess (21) a second flow transfer cross-section opens between the second elastic annular seal (14) and the cylinder tube (1).