Coaxial Three-Position Shift Module for Reliable Piston Force
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Solution Overview
Problem
Existing three-position shift modules for vehicles lack sufficient radial piston forces for reliable switching movements, leading to inefficiencies in gear shifting.
Innovation Solution
The design features shifting pistons with approximately equal effective pressure areas, a coaxial through-opening for the first shifting piston, and a partition wall separating the first and second shifting cylinders, with a stop on the shifting rod to manage piston movements and maintain pressure, allowing for reliable transitions between shift positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single switching piston is used to actuate the switching rod, then the device complexity is reduced, but the piston force becomes insufficient for reliable switching movement
Solution Approach 1:
The switching mechanism is divided into two independent switching pistons (first switching piston in first switching cylinder, second switching piston in second switching cylinder) that act on the switching rod in sequence. Each piston has its own pressure chamber and actuation mechanism, allowing the switching force to be distributed across multiple stages rather than requiring a single high-force piston.
2Force
If the second switching piston is pressurized to achieve reliable switching to the third position, then the piston force is increased, but the switching time increases due to prior venting requirements
Solution Approach 1:
The first switching piston is pressurized in advance to maintain pressure readiness. When switching from the third to first position is required, the first switching cylinder is already pressurized and can immediately actuate the switching rod once the second piston retracts, eliminating the need for prior venting operations and reducing overall switching time.
3Ease of operation
If the first switching cylinder is vented before switching back to the first position, then the switching sequence is simplified, but disturbing noises occur due to the first switching piston striking its position
Solution Approach 1:
The system allows the first switching piston to remain in its extended position under maintained pressure, using the pressure itself to hold the piston in place without requiring venting. This converts the potential harmful effect of rapid piston movement and impact into a beneficial holding force that prevents noise while simplifying the switching sequence.
4Volume of moving object
If the switching rod is guided through a coaxial opening in the partition wall, then the structural compactness is improved, but the radial extent constraints create design limitations
Solution Approach 1:
The switching rod is nested through the partition wall via a coaxial opening, with the rod passing through both the first and second switching cylinders. The stop feature is nested on the switching rod at a specific distance from the second switching piston, creating a compact hierarchical structure where components are arranged concentrically to minimize overall volume while maintaining functional independence.
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 configuration ensures reliable switching to all three positions, minimizing shifting time and noise, while maintaining piston force and preventing overshooting, even at the highest spring restoring force position.
Implementation Method 1
a spring force, with both switching pistons being in their retracted position under the influence of the spring force
Implementation Method 2
pressurized pneumatically
Data Source
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AI summary
The invention relates to a three-position switching module with a switching rod 13, which is axially displaceable into a first, a second, and a third switching position and on which a switching fork 29 is fixedly arranged, wherein the switching rod 13 can be axially driven against a spring force by a first switching piston 23, which can be pressurized on one side, and by a second switching piston 20, which can be pressurized on one side in the same direction as the first switching piston 23. The first switching piston 23 is displaceably arranged in a first switching cylinder 1, and the second switching piston 20 is displaceably arranged in a second switching cylinder 5, which is coaxial with the first switching cylinder 1.The switching pistons 20 and 23 have at least approximately equal pressure-acting surfaces, and the first switching piston 23 has a coaxial through-opening 24 with which it is guided axially displaceably and sealed on the switching rod 13, and the switching rod 13 projects through a coaxial opening 9 in a partition 7 separating the first switching cylinder 1 from the second switching cylinder 5. A stop 27 is arranged on the switching rod 13 at a distance from the second switching piston 20, the radial extent of which is smaller than the radial extent of the coaxial opening 19 of the partition 7 and larger than the radial extent of the through-opening 24 of the first switching piston 23.