Electric Axle Rotor With Eccentric Mass for Pleasant Sound Feedback
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Solution Overview
Problem
Fully electric motor vehicles produce unpleasant high-frequency sounds due to the use of electric motors designed for high speeds, which can distract or bother drivers by reducing their awareness of the vehicle's operating regime.
Innovation Solution
An electric axle design featuring a rotor with an additional mass coupled in a movable manner and guiding means to constrain its displacement radially, causing the rotor to vibrate and produce a pleasant, audible sound representative of the motor's operating regime, thereby enhancing driver involvement and awareness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If electric motors are designed for high speeds to reduce bulk and weight, then the motor size and weight are reduced, but the produced sounds become unpleasant high-frequency whistles that bother the driver
Solution Approach 1:
The patent applies mechanical vibration by adding an eccentric mass to the rotor that creates controlled vibrations at specific frequencies. This vibration mechanism generates pleasant low-frequency sounds that mask the unpleasant high-frequency whistles produced by the high-speed electric motor, thereby resolving the contradiction between motor compactness and acoustic comfort.
2Productivity
If electric motors rotate at high speeds to improve performance, then the motor efficiency is improved, but the driver's awareness of the operating regime is reduced due to unpleasant sounds
Solution Approach 1:
The patent converts the harmful high-frequency whistle sounds generated by high-speed motor operation into beneficial low-frequency pleasant sounds through the eccentric mass vibration mechanism. This allows the motor to operate at high speeds for improved efficiency while the generated vibrations provide pleasant acoustic feedback that enhances driver awareness and engagement.
3Object-generated harmful factors
If additional mass is added to the rotor for sound generation, then pleasant sounds are produced, but the rotor balance and potential vibrations are affected
Solution Approach 1:
The patent employs a movable eccentric mass that can dynamically adjust its position along the rotor axis within guiding means. This dynamic configuration allows the mass to be positioned optimally for sound generation while maintaining rotor balance, and can be adjusted to compensate for any imbalance, thereby resolving the contradiction between sound quality and rotor stability.
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 design generates pleasant sounds at low operating regimes, mimicking internal combustion engine sounds, and reduces noise intensity as motor regimes increase, improving driver engagement and reducing noise distractions.
Implementation Method 1
at least one additional mass coupled to the rotor in a movable manner relatively to the rotor, and guiding means configured to constrain a displacement of the mass along a direction fixed to the rotor and having at least one radial component with respect to the rotor axis, the mass being arranged eccentrically with respect to the rotor axis by the guiding means
Data Source
AI summary
An electric axle for a motor vehicle is disclosed. The electric axle includes an electric motor, a transmission assembly to transmit mechanical power delivered by the electric motor to traction means of the motor vehicle for moving the motor vehicle, wherein one between the electric motor and the transmission assembly comprises a rotor rotatable around a rotor axis in response and corresponding to the mechanical power delivered by the motor, and wherein the electric axle comprises at least one additional mass coupled to the rotor in a movable manner relatively to the rotor, characterized by comprising guiding means configured to constrain a displacement of the mass along a direction fixed to the rotor and having at least one radial component with respect to the rotor axis, the mass being arranged eccentrically with respect to the rotor axis by the guiding means.