Speed-changing Transmission Coupling Device for Compact EV Drivetrains
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Solution Overview
Problem
Conventional speed-changing and differential transmissions in electric vehicles require significant installation space due to the need for decoupling devices like friction clutches or sliding sleeves, which compromise the compactness of coaxial transmissions.
Innovation Solution
A speed-changing and differential transmission with a coupling device that uses positive engagement elements, such as form-locking elements, to selectively connect and disconnect components within the transmission, allowing for efficient decoupling without increasing the transmission's installation space, and enabling efficient power transfer and reduced losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional decoupling devices (friction clutch or sliding sleeve) are used, then decoupling function is achieved, but installation space increases
Solution Approach 1:
The coupling device merges the decoupling function directly into the existing planetary stage structure by utilizing the planet carrier as both a structural component and a coupling element. The form-locking elements are integrated within the planet carrier, eliminating the need for separate decoupling devices and maintaining compact coaxial transmission geometry.
Solution Approach 2:
The form-locking elements are nested within the planet carrier structure, with coupling protrusions and coupling recesses integrated into the existing planetary mechanism. This nesting approach allows the decoupling function to be embedded within the transmission volume without adding external components.
2Adaptability or versatility
If friction clutch is used for decoupling, then decoupling is achieved, but energy losses increase
Solution Approach 1:
The invention replaces the friction-based decoupling mechanism with a form-locking positive engagement system. The coupling protrusions and recesses create direct mechanical interlocking without friction slides, eliminating energy losses associated with friction clutch operation during decoupling and coupling transitions.
3Adaptability or versatility
If sliding sleeve is used for decoupling, then decoupling function is provided, but device complexity increases
Solution Approach 1:
The invention extracts the decoupling function from separate sliding sleeve components and integrates it directly into the planet carrier structure. The form-locking elements are taken out as independent functional features within the planet carrier, eliminating the need for additional sliding sleeve components and reducing overall device complexity.
4Adaptability or versatility
If conventional decoupling devices are added, then versatility is improved, but manufacturing complexity increases
Solution Approach 1:
The coupling device merges the decoupling function with the planet carrier manufacturing process. The form-locking elements are integrated into the planet carrier structure, allowing both components to be manufactured as a single unit or pre-assembled assembly, thereby simplifying the manufacturing process compared to adding separate decoupling devices.
Data Source
AI summary
A speed-changing and differential transmission includes a speed-changing section and a differential section. The speed-changing section has an input stage and a load stage. The sun wheel of the load stage can be operatively connected to at least one planet wheel of the input stage via a planet carrier. At least one planet wheel of the load stage can be operatively connected to the annulus of the input stage via a planet carrier. One of these operative connections is configured as a selectable connection and the other is configured as a fixed connection such that through use of a coupling device, the annulus of the input stage can be operatively coupled to the planet carrier of the load stage, or the sun wheel of the load stage can be operatively coupled to the planet carrier of the input stage.