Gearshift Selector Piston Venting to Prevent Air Intake
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Solution Overview
Problem
Hydraulic cylinders in gear-change selectors for motor vehicles face issues with air inclusion and fluid loss due to venting, leading to premature seal wear and potential dry running during extended periods of non-use.
Innovation Solution
A piston design with pressure- and temperature-dependent vent channels, featuring complementary sealing portions and a rubber-elastic sealing element that adjusts cross-sectional area based on pressure and temperature, ensuring reliable venting without air intake or dry running.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous venting is implemented to prevent air inclusion, then air inclusions are removed from the hydraulic cylinder, but working fluid drains away continuously leading to air intake and dry running during extended non-use periods
Solution Approach 1:
The vent channel's cross-sectional area is made dynamically adjustable through the elastomeric sealing element that deforms in response to pressure and temperature changes. During operation, the element allows sufficient venting area to remove air inclusions. During non-use periods, reduced pressure and temperature cause the element to return to its original shape, closing the vent channel to prevent fluid loss and air intake.
Solution Approach 2:
The sealing element's physical properties (shape and cross-sectional area) are changed in response to varying pressure and temperature parameters. Under operating conditions (higher pressure and temperature), the element deforms to provide an open vent channel. Under storage conditions (lower pressure and temperature), the element returns to its original shape, closing the vent channel.
2Reliability
If venting is enabled to remove air inclusions, then air is vented from the hydraulic system, but seal wear increases due to premature wear from pressure fluctuations and air expansion
Solution Approach 1:
The elastomeric sealing element provides dynamic control of the vent channel, opening it only when necessary during operation to remove air inclusions and closing it during non-use periods to protect the seal from damage caused by pressure fluctuations and air expansion.
Solution Approach 2:
The sealing element utilizes the natural thermal and pressure conditions of the hydraulic system to its advantage. The same pressure and temperature conditions that indicate active operation also cause the element to open the vent channel, while the absence of these conditions during storage automatically closes the channel, protecting the seal without requiring additional control mechanisms.
3Productivity
If vent channel cross-sectional area is increased to improve venting efficiency, then air inclusions are vented more effectively, but working fluid loss increases during non-use periods
Solution Approach 1:
The vent channel's cross-sectional area is dynamically adjusted based on operating conditions. During operation, the sealing element deforms to provide a larger open area for efficient venting of air inclusions. During non-use periods, the element returns to its original shape, reducing the open area to minimal levels to prevent fluid loss.
Solution Approach 2:
The physical state of the sealing element changes in response to pressure and temperature parameters, thereby changing the vent channel's cross-sectional area. Under operating parameters, the element provides maximum venting area. Under storage parameters, the element minimizes the open area while still allowing pressure equalization.
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 piston design maintains efficient venting at varying temperatures and pressures, preventing air inclusion and fluid loss, thus extending seal life and maintaining system functionality during non-use periods.
Implementation Method 1
a pressurisation of the sealing element by the working fluid leads to a temperature- and pressure-dependent elastic deformation of the sealing element
Implementation Method 2
The second sealing portion allows venting above the first pressure
Data Source
AI summary
A piston, in particular for a gear-change selector, including a piston body with a piston skirt and with a piston end face which can be pressurised with a working fluid. The piston includes a first sealing portion and a second sealing portion. The piston body and the first sealing portion have mutually complementary geometries so that they form a first vent channel. The first vent channel is arranged in a hydraulic series circuit with the second sealing portion. The second sealing portion prevents venting up to a first pressure and allows this above the first pressure. The invention furthermore concerns a gear-change selector and a gearshift for a vehicle.