High-Speed Electric Drive Unit for Compact High-Torque Output
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Solution Overview
Problem
Existing electric drives are not suitable for construction and material handling machines due to low power density, making it difficult to replace hydraulic drives without extensive redesign, as they cannot provide the required high torques at low speeds within confined installation spaces.
Innovation Solution
A high-speed electric motor combined with a speed-reducing transmission, forming a plug-and-play module that reduces the motor speed to achieve a torque density of over 20 Nm/l, allowing installation in confined spaces and providing high torques at low speeds, without the need for reconfiguring driven system units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an electric motor is used to replace hydraulic drives, then fuel savings and local zero emission are achieved, but the power density is too low to provide high torques at low speeds within confined installation spaces
Solution Approach 1:
The patent combines a high-speed electric motor with a speed-reducing transmission unit into an integrated drive unit. This merging allows the electric motor to operate at its optimal high speed while the transmission reduces the speed and increases torque to match the requirements of construction machinery, achieving both emission reduction and sufficient power density.
Solution Approach 2:
The patent employs a dynamic speed reduction approach where the electric motor runs at variable high speeds and the transmission dynamically adjusts the output speed and torque. This allows the drive unit to adapt to different operational requirements while maintaining high power density through optimal motor speed operation.
2Power
If the electric motor is built larger to provide sufficiently high power or torque, then the torque requirement is met, but the installation space requirement cannot be satisfied
Solution Approach 1:
Instead of increasing motor size, the patent maintains a compact motor size and uses dynamic speed reduction through the transmission unit. The motor operates at high speeds with moderate torque, and the transmission dynamically converts this to high torque at low speeds, achieving the required torque output without increasing the motor's physical dimensions.
Solution Approach 2:
The patent changes the operational parameters by allowing the electric motor to run at higher speeds than traditional applications. This parameter change enables the motor to produce sufficient power in a smaller package, and the transmission then converts this high-speed power to the required high-torque low-speed output, maintaining compact dimensions.
3Power
If the speed of the electric motor is increased to improve power density, then the power density increases, but the driven system cannot handle increased speeds without structural adjustments
Solution Approach 1:
The transmission unit acts as an intermediary between the high-speed electric motor and the driven system. It accepts the high-speed input from the motor, performs speed reduction and torque multiplication, and delivers the appropriate low-speed high-torque output to the driven system, protecting it from incompatible speed levels while enabling the motor to operate at optimal speeds.
Solution Approach 2:
By merging the high-speed electric motor with the speed-reducing transmission into an integrated drive unit, the patent creates a unified system where the motor's high-speed capability and the transmission's speed-reduction function work together. This combined unit presents a compatible interface to the driven system while allowing the motor to operate at speeds that maximize power density.
4Object-affected harmful factors
If a conventional hydraulic motor is replaced by an electric drive, then electrification advantages are achieved, but the speeds of the drive unit cannot be increased as the driven system would no longer be able to operate in the predetermined manner
Solution Approach 1:
The transmission unit serves as an intermediary that decouples the speed relationship between the electric motor and the driven system. It allows the motor to operate at high speeds for improved power density and emission performance, while simultaneously delivering the predetermined low speeds required by the driven system, thus maintaining operational compatibility during electrification.
Solution Approach 2:
The patent implements a dynamic speed conversion system where the transmission unit continuously adjusts the speed ratio between the electric motor and the driven system. This dynamic adaptation allows the motor to operate at optimal high speeds for efficiency and emission reduction, while the driven system receives the predetermined speeds it requires for proper operation.
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 enables the electric drive unit to meet the torque and speed requirements of machines like cranes, offering a compact design that can replace hydraulic drives without system redesign, providing torques in the range of 500 to 2,000 Nm at low speeds.
Implementation Method 1
a speed-reducing transmission connected to the drive motor, which reduces the motor speed of the electric motor to the output speed of the drive unit
Data Source
AI summary
The invention relates to a drive unit for a construction and/or material handling machine or lifting equipment such as a crane, comprising a torque density of more than 20 Nm/l at a predetermined output speed, wherein the drive unit comprises a drive motor and a connected transmission, wherein a fast-running electric motor is provided as the drive motor, wherein the motor speed thereof is at least two times said output speed of the drive unit and is reduced by the transmission by a factor of at least 2 to the output speed of the drive unit.