Electric Drive Train Torque Modulation for Gear Mesh Noise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric vehicle drivetrains produce disturbing noises due to variable tooth stiffness in gear meshing, which are not masked by combustion engines, leading to tonal noise that increases with transmitted torque.
Innovation Solution
A method and device that superimpose a periodic torque change signal on the control signal to simulate tooth stiffness, reducing noise by alternating drive torque in phase with tooth stiffness changes, without additional hardware costs or weight, using software extensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a toothed gear stage is used to convert speed and drive torque in an electric motor drive, then mechanical advantage and torque multiplication are achieved, but variable tooth stiffness causes periodic torque changes and disturbing tonal noise
Solution Approach 1:
The invention applies periodic action by superimposing a periodic torque change signal on the control signal to the electric motor. This signal has the same frequency as the tooth stiffness variation and is synchronized with the gear meshing cycle. By applying periodic torque modulation that matches the natural frequency of the gear system, the method counteracts the periodic stiffness variations and reduces the resulting tonal noise while maintaining the necessary torque transmission through the gear stage
2Power
If the drive torque is increased to meet vehicle performance requirements, then the vehicle can deliver higher power output, but the gear meshing noise increases proportionally with the transmitted torque
Solution Approach 1:
The invention applies parameter changes by dynamically modulating the torque command signal to the electric motor based on the instantaneous gear meshing phase. The control system varies the torque parameter periodically at the same frequency as the tooth stiffness variation, creating a counteracting torque component. This allows the system to maintain high average torque for power delivery while reducing the peak-to-peak torque variations that cause noise, effectively decoupling power output from noise intensity
3Object-generated harmful factors
If additional noise reduction hardware is added to the drive train, then gear noise can be actively reduced, but the vehicle weight and manufacturing costs increase
Solution Approach 1:
The invention applies mechanics substitution by replacing potential mechanical noise reduction devices (such as additional dampers, floating supports, or active vibration control actuators) with a software-based control solution. The periodic torque change signal is generated and applied through the existing electric motor control system, eliminating the need for additional mechanical noise reduction hardware while achieving effective noise suppression. This substitutes a mechanical approach with an electrical/control approach that leverages the existing motor actuation capability
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a vehicle drive train and to a method for operating a drive train with electromotive drive (4), wherein a rotational speed and a drive torque of the drive (4), which are convertible via a toothed transmission stage (12) for an output (19), and the drive (4) is controlled by a control signal (40), wherein the control signal (40) has superimposed thereon a periodic torque change signal (5), which is in phase with a tooth stiffness change of the toothed transmission stage (12), wherein a signal strength of the torque change signal (5) with reducing tooth stiffness is weaker than with increasing tooth stiffness.