Vehicle Drive Unit Layout With Positive-Locking Shift and Low Drag
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Solution Overview
Problem
Existing drive units for vehicles are not compact and efficient, with significant drag losses and inefficiencies in torque transmission due to the use of friction-locking shift elements and non-optimal gear configurations.
Innovation Solution
A drive unit featuring two electrical machines, a manual gearbox with multiple gears, and a differential, utilizing positive-locking shift elements and a nested spur gear configuration to reduce drag losses and increase efficiency, with a single sliding sleeve and actuator for compactness and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If friction-locking shift elements are used in existing drive units, then the structure is simpler, but drag losses increase and efficiency decreases
Solution Approach 1:
The patent replaces friction-locking shift elements with positive-locking shift elements that use mechanical interlocking (claws and grooves) instead of friction-based engagement. This substitution eliminates drag losses associated with friction while maintaining structural functionality through precise mechanical engagement of the shift elements with the gear sets.
2Device complexity
If multiple independent sliding sleeves and actuators are used for each shift element, then shift control is more precise, but the device becomes less compact and more expensive
Solution Approach 1:
The patent merges multiple independent sliding sleeves into a single sliding sleeve that controls multiple shift elements simultaneously. This single sleeve is actuated by one actuator, reducing the number of components while maintaining precise shift control through the integrated design of the sleeve and its engagement points with the shift elements.
Solution Approach 2:
The single sliding sleeve performs multiple functions by controlling both the first and second shift elements through its axial displacement. This multi-functional component achieves precise shift control for different gear combinations without requiring separate actuators, thereby simplifying the overall device structure.
3Adaptability or versatility
If electrical machines are arranged non-optimally, then connection to gear sets is easier, but torque summation and independent operation capabilities are reduced
Solution Approach 1:
The patent employs a nested arrangement where the first and second planetary gear sets are positioned concentrically, with the second gear set nested within or adjacent to the first. This nested configuration allows both electrical machines to be efficiently connected to their respective gear sets while enabling torque summation at the common output, and maintains the capability for independent operation through the positive-locking shift elements.
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 enhances efficiency by reducing drag losses and enabling compact design, allowing for torque summation and independent operation of electrical machines, while saving space and weight through axial and radial arrangement of components.
Implementation Method 1
a first electrical machine (EM1), a second electrical machine (EM2)... wherein in a first shift position of the first sliding sleeve the first shift element is closed and the second electrical machine is connected with an actuating effect to a shaft of the first planetary gear set
Implementation Method 2
the first spur gear stage has a first spur gear and a second spur gear that engage in a tooth mesh with each other... the second spur gear stage has a third spur gear and a fourth spur gear, which are engaged in a tooth mesh with each other
Implementation Method 3
a first planetary gear set, which has a first sun shaft, a first hollow gear shaft and a first web shaft... The first web shaft carries several planetary gears which mesh with the first sun shaft and with the first hollow gear shaft
Implementation Method 4
a first positive-locking shift unit having a first shift element, a second shift element and a first sliding sleeve... wherein in a first shift position of the first sliding sleeve the first shift element is closed
Data Source
AI summary
A drive unit has first and second electrical machines arranged axially parallel, a manual gearbox arranged axially parallel to the electrical machines, a differential, a drive shaft, an output shaft, and a positive-locking shift unit having a first shift element, a second shift element, and a sliding sleeve displaceable via a first actuator into one of three shift positions. In a first shift position, the first shift element is closed and the second electrical machine is connected to the drive shaft with an actuating effect; in a second shift position, both shift elements are open and the second electrical machine is decoupled from the gearbox; in a third shift position, the second shift element is closed and the second electrical machine is connected to the output shaft with an actuating effect. The drive shaft is hollow, and the output shaft is arranged within the drive shaft.