Electric Motor Propulsion Drive for Mobile Machines
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Solution Overview
Problem
Conventional wheel loaders rely on internal combustion engines for propulsion and working drives, which are inefficient and costly, especially when transitioning between low and high driving speeds, and lack optimal tractive power profiles.
Innovation Solution
A propulsion drive system featuring an electric motor with distinct operating ranges for torque and power, coupled with a transmission that adapts to switch between gears for efficient speed transitions, optimizing tractive power delivery and reducing energy losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If an internal combustion engine is used for propulsion drive, then the mobile machine can achieve high driving speeds, but energy efficiency deteriorates and energy consumption increases
Solution Approach 1:
The patent replaces the internal combustion engine with an electric motor for the propulsion drive. The electric motor is connected to the transmission system, which includes a first gear for low driving speeds and a second gear for high driving speeds. This substitution eliminates the inefficiencies of combustion engines while maintaining the capability to achieve both low and high driving speeds with optimal energy efficiency.
2Speed
If an internal combustion engine is used for propulsion drive, then the mobile machine can operate across a wide speed range, but the tractive power profile becomes suboptimal
Solution Approach 1:
The patent employs a dynamic transmission system with two distinct gears optimized for different speed ranges. The first gear is optimized for low driving speeds with high tractive power, while the second gear is optimized for high driving speeds with reduced tractive power requirements. The system dynamically switches between gears based on the required driving speed, ensuring optimal tractive power delivery across the entire operating range.
3Speed
If conventional propulsion systems are used, then the mobile machine can transition between low and high speeds, but energy losses increase during speed transitions
Solution Approach 1:
The patent utilizes an electric motor with variable operational parameters that can be optimized for different operating conditions. The motor can adjust its torque and speed characteristics independently of the gear selection, allowing for smooth transitions between low and high speed gears with minimal energy loss. The control system optimizes motor parameters during gear transitions to maintain energy efficiency.
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 system provides optimized tractive power profiles, reduces energy consumption, and minimizes gear changes, enhancing efficiency and reducing costs by operating the electric motor in specific ranges suited for low and high driving speeds.
Implementation Method 1
an electric motor (11) having a first range (I), in which a torque is constant as a rotational speed rises, and a second range (II), in which a power is constant as the rotational speed rises
Data Source
AI summary
A propulsion drive system for a mobile machine includes an electric motor having a first range, in which a torque is constant as a rotational speed rises, and a second range, in which a power is constant as the rotational speed rises. The propulsion drive system further includes a transmission operatively connected mechanically to the electric motor. The propulsion drive system is configured to be transferred, via the transmission, from a state for relatively low driving speeds into a state for relatively high driving speeds of the mobile machine. The electric motor and the transmission are adapted to one another in such a way that the electric motor can be operated in the state for relatively low driving speeds exclusively in the first and second range.