Two-Speed Electric Drive Unit With Hollow-Shaft Differential Layout
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Solution Overview
Problem
Existing drive units for vehicles often require larger electric motors to meet drive requirements, leading to inefficiencies and increased space usage, as they are not optimized for compactness and frequent operation in higher efficiency ranges.
Innovation Solution
A drive unit comprising an electric machine, a gearbox, and a differential, where the electric machine is coupled to the differential via the gearbox, with a 2-speed transmission and freewheel or multi-plate clutch mechanisms allowing for efficient torque transmission and compact design, enabling the motor to operate more frequently in its higher efficiency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a larger electric motor is used to meet drive requirements, then the drive unit can provide sufficient power, but the installation space increases and efficiency decreases
Solution Approach 1:
The patent applies a 2-speed transmission system that allows the electric motor to operate in different gear ratios depending on driving conditions. This dynamic gear switching enables a smaller motor to deliver high power when needed (through gear multiplication) while maintaining efficient operating speeds during normal operation, thus resolving the contradiction between power output and motor size.
Solution Approach 2:
The transmission system changes the operating parameters of the motor by providing two distinct gear ratios. The first gear ratio allows the motor to operate in a higher efficiency range during normal driving, while the second gear ratio provides mechanical advantage for high-power situations. This parameter change enables a smaller motor to meet both power and efficiency requirements.
2Adaptability or versatility
If a 2-speed transmission with multiple gears is implemented, then operational flexibility and efficiency are improved, but device complexity increases
Solution Approach 1:
The transmission system is segmented into two distinct stages: a first stage with a first pinion and first gear for normal operation, and a second stage with a second pinion and second gear for high-power operation. This segmentation allows each stage to be optimized for its specific function while keeping the overall system manageable in complexity through modular design.
Solution Approach 2:
The clutch mechanism provides dynamic switching between the two gear stages based on driving conditions. This dynamic engagement and disengagement capability allows the system to adapt to different operational requirements without requiring a complex continuously variable transmission, thereby achieving operational flexibility with controlled complexity.
3Loss of energy
If the motor operates in higher efficiency range more frequently, then energy efficiency improves, but the ability to meet peak power demands may be compromised
Solution Approach 1:
The transmission system changes the operating parameters of the motor by providing two distinct gear ratios. The first gear ratio allows the motor to operate in a higher efficiency range during normal driving, while the second gear ratio provides mechanical advantage for high-power situations. This parameter change enables a smaller motor to meet both power and efficiency requirements.
Solution Approach 2:
The transmission system acts as an intermediary between the motor and the wheels, allowing the motor to operate in its efficient range while still delivering the required peak power to the wheels through gear multiplication. The clutch mechanism serves as a mediator that selectively engages different gear stages based on power demands.
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 allows for a smaller motor to cover drive requirements, achieving higher efficiency and operational flexibility while reducing the number of components and design complexity, resulting in a more compact and cost-effective solution.
Implementation Method 1
an electric machine (12), in particular an asynchronous machine or a synchronous machine
Implementation Method 2
a first pinion (30) arranged on the hollow shaft (18) and rotationally fixed to the hollow shaft (18), and a first gear (32) arranged on the intermediate shaft (28), wherein the first gear (32) meshes with the first pinion (30)
Implementation Method 3
a first clutch device (34) is provided by means of which the first gear (32) and the intermediate shaft (28) can be rotationally fixedly coupled
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a drive unit (10) comprising an electric machine (12), a transmission (14), and a differential (16), wherein the electric machine (12) is coupled to the differential (16) via the transmission (14) so that the electric machine (12) can drive the differential (16) via the transmission (14), wherein the electric machine (12) has a rotor shaft (18) designed as a hollow shaft (18), and wherein the differential (16) is coupled to two axle side shafts (20, 22), one of which passes through the hollow shaft (18). It is proposed that the transmission (14) be designed as a 2-speed transmission (14) with an intermediate shaft (28).