Electric Drive Planetary Gear Switching Mechanism
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Solution Overview
Problem
Existing electric drives for motor vehicles are cumbersome due to high part counts, weight, installation space requirements, and costs, particularly in implementing multiple gears with conventional planetary gear sets.
Innovation Solution
The electric drive integrates a single planetary gear set with shared actuators for multiple switching elements, utilizing a displacement ring gear and hollow/solid shafts to achieve compact, efficient gear switching, allowing for three gears with reduced parts and space, and eliminating the need for separate actuators for each switching element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple separate actuators are used for each switching element in a conventional planetary gear set, then reliable gear switching is achieved, but the number of parts, weight, installation space requirement and costs increase significantly
Solution Approach 1:
The patent combines multiple switching elements (first switching element for coupling ring gear to rotor, second switching element for coupling ring gear to housing) into a single integrated switching element that can perform both coupling functions. This merging reduces the number of actuators from multiple separate units to a single actuator, thereby reducing part count, weight, and installation space while maintaining the reliability of gear switching through the integrated design.
Solution Approach 2:
The single switching element is designed with multi-functionality to perform both the function of the first switching element (coupling ring gear to rotor) and the second switching element (coupling ring gear to housing). This universal component achieves the same gear switching reliability as multiple separate actuators but with reduced complexity by consolidating multiple functions into one component.
2Adaptability or versatility
If a conventional planetary gear set with multiple switching elements is used, then multiple gears are achieved, but the installation space requirement and weight increase
Solution Approach 1:
The patent merges multiple switching elements into a single integrated switching element that provides the same multiple gear ratio capabilities. This consolidation maintains the adaptability for multiple gears while significantly reducing the installation space requirement by eliminating redundant components and actuators that would be present in a conventional multi-element design.
Solution Approach 2:
The single switching element is designed with a nested structure where multiple functional components are integrated within a compact arrangement. The switching element incorporates both coupling functions (ring gear to rotor, and ring gear to housing) in a nested configuration that minimizes the overall footprint and installation space while maintaining multiple gear ratio versatility.
3Ease of operation
If multiple separate actuators are provided for each switching element, then independent control of each gear is achieved, but the costs and number of parts increase
Solution Approach 1:
The patent combines the control functions of multiple separate actuators into a single actuator that controls the integrated switching element. This merging maintains independent control capability for each gear ratio through the single actuator's ability to selectively engage different coupling functions, while reducing the quantity of actuators from multiple separate units to just one, thereby lowering costs and part count.
Data Source
AI summary
An electric drive for a motor vehicle includes a housing, an output shaft, an electric engine, which has a stator and a rotor rotatable relative to the stator, a planetary gear set arranged in the housing, which has a sun gear, a ring gear and a planetary carrier, which is non-rotatably connected to the output shaft, having a first switching element, by means of which the ring gear can be non-rotatably coupled to the rotor, and a second switching element, by means of which the ring gear can be non-rotatably coupled to the housing. The first switching element and the second switching element are coupled to each other via a first coupling element and thereby can be operated together by a single first actuator common to the first switching element and the second switching element.