Hydraulic Selector Rod Shifting With a Common Tank Line
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Solution Overview
Problem
Existing vehicle transmission shifting systems face challenges in achieving reliable and precise shifting behavior due to imprecise hydraulic and mechanical factors, leading to undesired axial movements and incorrect gear positions.
Innovation Solution
A shifting apparatus with a selector rod hydraulically loaded through pressure chambers, featuring a common tank line and integrated valve unit, and air channels to manage hydraulic pressure and prevent air ingress, ensuring stable pressure conditions and precise gear shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate valve units are assigned to each return line, then individual pressure control is possible, but manufacturing tolerances cause different shut-off pressures leading to larger movement play and less precise shifting
Solution Approach 1:
The patent combines two separate valve units into a single common valve unit that serves both return lines. This merging eliminates the tolerance differences between separate valves, ensuring identical shut-off pressures for both pressure chambers. The common valve unit is positioned in the common tank line, allowing it to control hydraulic medium flow for both selector rod free ends uniformly, thereby achieving precise shifting without the need for multiple independently adjusted valves.
2Stability of the object's composition
If a common tank line is used for both pressure chambers, then stable pressure conditions are achieved, but the system becomes more sensitive to pressure fluctuations
Solution Approach 1:
The common valve unit in the common tank line acts as a pressure-regulating feedback mechanism. When pressure fluctuations occur in either return line, the valve unit automatically adjusts to maintain stable pressure conditions in both pressure chambers. The valve responds to pressure changes and modulates hydraulic medium flow accordingly, providing active compensation that ensures consistent selector rod positioning despite external pressure variations.
3Stability of the object's composition
If hydraulic medium flows freely into the tank, then pressure equalization is achieved, but air can ingress into the pressure chambers causing incorrect positions
Solution Approach 1:
The common valve unit serves as an intermediary component between the pressure chambers and the hydraulic tank. It controls and mediates the flow of hydraulic medium into the tank, allowing pressure equalization while preventing air ingress. The valve unit's positioning and design enable it to filter or block air bubbles from entering the pressure chambers during the hydraulic medium's return flow, thus eliminating the harmful effect of air contamination while maintaining pressure stability.
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 a stable and precise shifting behavior, avoiding accidental incorrect positions and enhancing driving comfort by maintaining consistent gear positions even under pressure fluctuations.
Implementation Method 1
the two rod free ends of the selector rod can be loaded hydraulically... Hydraulic medium (for example, oil) passes by way of this into the pressure chambers, in order for it to be possible for the two rod free ends to be loaded with hydraulic pressure
Implementation Method 2
The tank line which is common to the two pressure chambers provides stable physical preconditions in a technically simple way for precise pressure conditions in the two hydraulic chambers
Data Source
AI summary
The disclosure relates to a shifting apparatus for shifting gear stages of a vehicle transmission. The shifting apparatus comprises at least one selector rod which is translationally movable along a shifting direction and the two rod free ends of which are mounted in a manner which can be loaded hydraulically in each case in a pressure chamber for hydraulic medium. The shifting apparatus has a pressure connector and a hydraulic pressure line which is connected to it at each pressure chamber. Moreover, a tank connector and a hydraulic return line which is connected to it are arranged at each pressure chamber. The two return lines open into a common tank line for connection to a hydraulic tank. Moreover, the disclosure relates to a towing vehicle with a shifting apparatus of this type.