Planetary EV Drive Unit With Single-Actuator Sequential Shifting
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Solution Overview
Problem
Existing drive units for electric vehicles lack a compact and energy-efficient design, particularly in systems incorporating a single electric machine and a manual gearbox with multiple gears.
Innovation Solution
A drive unit comprising an electric machine and a manual transmission with multiple shift elements and planetary gear sets, where the second sun shaft is driven by the electric machine, the second web shaft serves as the gearbox output, and shift elements connect shafts in rotationally fixed or non-rotatable manners to achieve various gears, utilizing interlocking shift elements for enhanced efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a single electric machine is combined with a manual gearbox having multiple gears, then the drive unit achieves energy efficiency and compact design, but the structural complexity and difficulty of gear shifting increase
Solution Approach 1:
The manual gearbox is segmented into two separate planetary gear sets, each responsible for a specific gear ratio. The first planetary gear set provides the first gear ratio while the second planetary gear set provides the second gear ratio. This segmentation allows each gear set to be optimized independently and simplifies the shifting mechanism as each shift element only needs to engage one gear set at a time, reducing overall structural complexity while maintaining multiple gear ratios for energy efficiency
Solution Approach 2:
A single actuator is designed to control both shift elements (first and second shift elements) that engage the two different planetary gear sets. This multi-functional actuator reduces the number of actuating components needed while still enabling seamless transitions between first gear and second gear, thereby reducing structural complexity without compromising the energy efficiency benefits of having multiple gears
2Adaptability or versatility
If two planetary gear sets are coupled together with multiple shift elements, then multiple gear ratios are achieved, but the number of components and assembly complexity increase
Solution Approach 1:
The transmission system is divided into two independent planetary gear sets, where the first planetary gear set is dedicated to providing the first gear ratio and the second planetary gear set is dedicated to providing the second gear ratio. Each gear set has its own sun shaft, ring gear shaft, and web shaft that are independently configured. This segmentation enables the system to achieve multiple gear ratios through simple engagement/disengagement of shift elements rather than requiring a single complex gear set with many components
Solution Approach 2:
Instead of using a single planetary gear set with multiple complex mechanisms to achieve different gear ratios, the invention inverts the approach by using two simpler planetary gear sets where each set is optimized for a specific ratio. The shift elements work by selectively engaging or disengaging these pre-configured gear sets, thereby achieving gear ratio versatility with fewer total components and simpler assembly requirements
3Ease of operation
If shift elements connect shafts in rotationally fixed manner for gear shifting, then gear transitions are achieved, but drag losses and energy efficiency worsen
Solution Approach 1:
The shift elements are designed with dynamic engagement characteristics that minimize drag losses during gear transitions. The first and second shift elements can selectively connect the planetary gear sets in a controlled manner, allowing for smooth transitions between first gear and second gear. The dynamic design of the shift elements ensures that connections are made only when necessary for gear transitions, reducing continuous drag losses while maintaining full gear shifting capability when needed
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 compact, energy-efficient drive unit with reduced drag losses and cost advantages, enabling high energy efficiency in electric vehicles by allowing sequential gear shifting through a single actuator, thus optimizing space, weight, and assembly.
Implementation Method 1
two planetary gear sets coupled to one another, wherein the first planetary gear set has a first sun shaft, a first ring gear shaft, and a first web shaft, wherein the second planetary gear set has a second sun shaft, a second ring gear shaft, and a second web shaft
Data Source
AI summary
A vehicle drive unit has an electric machine and a manual gearbox with first and second shift elements and two planetary gear sets coupled to one another. Each gear set has a sun shaft, a ring gear shaft, and a web shaft. The second sun shaft is drivable by the electric machine and is configured as an output of the shift gear. The second ring gear shaft is connected rotationally fixed to the first web shaft, and the first sun shaft is connected rotationally fixed to a stationary component. When actuated, the first shift element connects the first ring gear shaft to an element of the first planetary gear set and/or of the second planetary gear set. When actuated, the second shift element connects the first ring gear shaft rotationally fixed to the second sun shaft or the second web shaft in order to shift a second gear.