Radial Planetary Gear in Electric Motor Rotor
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Solution Overview
Problem
Existing hybrid drive systems for motor vehicles face challenges in achieving a compact and efficient design, particularly at high speeds where the electric motor is subjected to significant stress due to centrifugal forces, and require a topology that balances torque transmission with space-saving constraints.
Innovation Solution
A drive system incorporating a planetary gear set with a sun gear, ring gear, and multiple planetary gears mounted on a carrier, where the ring gear is connected to the rotor and the sun gear is rotationally fixed to the stator, enabling a compact design with a small air gap for high efficiency, and featuring a coupling device for selective torque transmission that can be integrated into an existing transmission housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the electric motor is coupled by way of a transmission to the drive train, then the electric motor size and weight can be reduced for low-speed operation, but the electric motor is strongly stressed by centrifugal forces at high velocities
Solution Approach 1:
The planetary transmission is arranged inside the rotor in the radial direction, nesting the transmission components within the motor structure. This allows the electric motor to be smaller and lighter while still providing the necessary torque multiplication, reducing the motor size and weight for low-speed operation without compromising high-speed performance capability
Solution Approach 2:
The system dynamically switches between electric motor-driven mode at low speeds and internal combustion engine-driven mode at high speeds. The coupling device selectively connects or disconnects the internal combustion engine from the planetary gear carrier, allowing the system to adapt to different operating conditions and reduce centrifugal force stress on the electric motor at high velocities
2Volume of moving object
If the ring gear is arranged inside the rotor in the radial direction, then a compact and space-saving design is achieved, but the air gap between rotor and stator must be minimized to maintain efficiency
Solution Approach 1:
The ring gear is nested inside the rotor in the radial direction, placing the transmission components within the available space of the rotor structure. This nesting arrangement achieves a compact drive system volume while the air gap is maintained at minimal dimensions to reduce energy losses
Solution Approach 2:
The planetary transmission components are arranged in the radial dimension rather than extending axially, changing the spatial configuration from a longitudinal layout to a radial layout. This dimensional change enables compact volume while allowing precise control of the air gap between rotor and stator surfaces
3Force
If multiple planetary gears are mounted on the planetary gear carrier, then torque transmission capability is increased, but the device complexity increases
Solution Approach 1:
Multiple planetary gears are combined on a single planetary gear carrier, merging multiple torque transmission paths into one integrated structure. This increases the torque transmission capability while the carrier structure itself manages the complexity by providing a unified mounting platform for all planetary gears
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 reduces structural space while increasing torque, allows for efficient power transmission, and enables reduced input speed during high-speed operation, improving efficiency and allowing for rapid load takeover by the internal combustion engine without the need for gear downshifts, enhancing recuperative operation and smoothing torque irregularities.
Implementation Method 1
an electromechanical energy converter
Implementation Method 2
planetary gear set including a sun gear, a ring gear, and at least one planetary gear mounted on a planetary gear carrier
Implementation Method 3
the electric motor is strongly stressed, in particular, by the centrifugal forces
Data Source
AI summary
A drive system for a hybrid drive in a motor vehicle is provided. The drive system includes a drive machine with a rotor and a stator; a planetary gear set with a sun gear, a ring gear and at least one planetary gear mounted on a planetary carrier; and a coupling system, by way of which at least one other drive machine can be coupled to the drive system. The ring gear can be connected to the rotor in order to transmit drive power and is arranged inside the rotor in the radial direction. In particular, the sun gear of the drive system is non-rotatably mounted in relation to the stator; the planetary carrier is configured as a transmission output shaft; and a power take-off shaft, which is concentric with the ring gear, can be connected to the planetary carrier and to the coupling system.