Planetary Gear Switching Actuation via Common Axial Element
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Solution Overview
Problem
Transmissions with planetary gearsets face challenges in accessing and actuating shifting elements due to poor accessibility, leading to increased complexity and susceptibility to errors, often requiring expensive mechanical or hydraulic speed differential lock-ups.
Innovation Solution
A device with two switching elements actuated by a common longitudinal displacement element, where the first switching element creates a non-rotatable connection between the first and second elements, and the second switching element creates a connection between the second and third elements, simplifying actuation by moving the first and third elements together, thereby bypassing the planetary gearset and reducing differential speed bridging requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If mechanical or hydraulic speed differential lock-ups are used to actuate shifting elements in planetary gear transmissions, then the shifting elements can be actuated, but the device complexity and susceptibility to errors increase
Solution Approach 1:
The patent combines two separate switching elements (first and second switching elements) into a single common actuating element that operates both elements simultaneously. This merging reduces the overall complexity by eliminating the need for separate actuation mechanisms for each switching element, while still achieving the required function of engaging different gear combinations in the planetary gear set.
Solution Approach 2:
The common actuating element serves multiple functions: it actuates both the first switching element and the second switching element, and it can do so in different operational modes (with or without speed differential compensation). This multi-functional design replaces what would traditionally require separate specialized mechanisms, thereby reducing device complexity while maintaining operational capability.
2Ease of operation
If mechanical or hydraulic speed differential lock-ups are used to actuate switching elements, then the switching elements can be actuated, but susceptibility to errors increases
Solution Approach 1:
By merging the actuation of two switching elements into a single common actuating element, the patent reduces the number of potential failure points. Fewer separate mechanical or hydraulic mechanisms mean fewer components that could malfunction, thereby improving reliability while maintaining the ability to actuate both switching elements.
Solution Approach 2:
The common actuating element is designed to automatically coordinate the actuation of both switching elements through its inherent mechanical structure. This self-service mechanism eliminates the need for complex control systems or additional sensors that could introduce errors, as the actuation is achieved through direct mechanical coupling and geometric constraints built into the design.
3Ease of operation
If a common actuating element moves the second element in both displacement directions, then both switching elements can be actuated, but the tolerance chain increases
Solution Approach 1:
Instead of moving the second element (which is associated with both switching elements) in both displacement directions, the patent inverts the approach by keeping the second element stationary and moving the first and third elements together. This inversion reduces the tolerance chain because the common actuating element only needs to coordinate movement in one direction relative to a fixed reference point, rather than managing bidirectional movement with accumulated tolerances.
Solution Approach 2:
The patent segments the actuation function by separating the movement of the second element from the actuation process. The second element remains fixed while the first and third elements are moved together by the common actuating element. This segmentation isolates the tolerance-critical components and reduces the cumulative tolerance chain that would result from moving multiple elements in sequence.
4Ease of operation
If shifting elements in planetary gear transmissions are made accessible, then actuation is simplified, but the structural design becomes more constrained
Solution Approach 1:
The patent resolves the accessibility issue by transitioning from radial access (which would require complex external mechanisms) to axial access along the rotation axis. The common actuating element is positioned on the rotation axis and acts radially inward on the switching elements, allowing actuation from a dimension that does not interfere with the planetary gear structure. This dimensional change simplifies actuation while maintaining structural integrity.
Data Source
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AI summary
Device for switching a first switching element (SE1, A, B, E) and a second switching element (SE2, F, C, D), wherein a rotationally fixed, form-fitting connection between a first element (E1) and a second element (E2) can be established by the first switching element (SE1, A, B, E), and wherein a rotationally fixed, form-fitting connection between the second element (E2) and a third element (E3) can be established by the second switching element (SE2, F, C, D), wherein the actuation of the first switching element (SE1, A, B, E) takes place by longitudinal displacement of a common actuating element (BE, BE1, BE2, BE3) along a first displacement direction (T1), wherein the actuation of the second switching element (SE2, F, E, D) takes place by longitudinal displacement of the common actuating element (BE, BE1, BE2, BE3) along a second displacement direction (T2) opposite to the first displacement direction (T1), wherein in a first switching state (S1) the first switching element (SE1, A, B, E) is closed and the second switching element (SE2, F, C, D) is open, wherein in a second switching state (S2) the first switching element (SE1, A, B, E) is open and the second switching element (SE2, F, C, D) is closed, wherein the first element (E1) and the third element (E3) are coupled to one another so that a displacement of the first element (E1) by the common actuating element (BE, BE1, BE2, BE3) in one of the two displacement directions (T1, T2) leads to a displacement of the third element (E3) in the same direction, and vice versa, and wherein the second element (E2) is fixed in position in both displacement directions (T1, T2), and transmission (G) for a motor vehicle comprising such a device.