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Electrification has already started to have a noticeable impact on the global automotive industry. As a result, the drivetrains of hybrid (HEV) and full electric vehicles (EV) are facing many challenges, like increased requirements for NVH in high speed e-Drives and the need for performance improvements to deal with recuperation requirements. Motivated by the positive validation results of surface densified manual transmission gears which are also applicable for dedicated hybrid transmissions (DHTs) like e-DCTs, GKN engineers have been looking for a more challenging application for PM gears within those areas.
The question is quite broad, as there are different methods for setting various types of gears and complexity of gear assemblies, but all gears have a few things in common.
With the ongoing push towards electric vehicles (EVs), there is likely to be increasing focus on the noise impact of the gearing required for the transmission of power from the (high-speed) electric motor to the road. Understanding automotive noise, vibration and harshness (NVH) and methodologies for total in-vehicle noise presupposes relatively large, internal combustion (IC) contributions, compared to gear noise. Further, it may be advantageous to run the electric motors at significantly higher rotational speed than conventional automotive IC engines, sending geartrains into yet higher speed ranges. Thus the move to EV or hybrid electric vehicles (HEVs) places greater or different demands on geartrain noise. This work combines both a traditional NVH approach (in-vehicle and rig noise, waterfall plots, Campbell diagrams and Fourier analysis) - with highly detailed transmission error measurement and simulation of the complete drivetrain - to fully understand noise sources within an EV hub drive. A detailed methodology is presented, combining both a full series of tests and advanced simulation to troubleshoot and optimize an EV hub drive for noise reduction.
Ground bevel and hypoid gears have a designed motion error that defines parts of their NVH behavior. The surface structure is defined by the hard finishing process.
Noise issues from gear and motor excitation whine are commonly faced by many within the EV and HEV industry. In this paper the authors present an advanced CAE methodology for troubleshooting and optimizing such NVH phenomenon.
Which transmission system will come out on top is a hot topic in the automotive community. With multiple transmission-centric conferences on the horizon, there will be plenty of debate, but how much will the answer actually affect gear manufacturers, and when?
In order to reduce costs for development and production, the objective in gearbox development and design is to predict running and noise behavior of a gearbox without manufacturing a prototype and running expensive experimental investigations. To achieve this objective, powerful simulation models have to be set up in a first step. Afterwards, those models have to be qualified and compared to experimental investigations. During the investigation procedure of gearboxes, there are two possibilities to evaluate the running and noise behavior: quasi-static and dynamic investigations. In times of engine downsizing, e-mobility and lightweight design, the dynamic excitation behavior is becoming increasingly important.
Software Providers Examine the Dynamic Behavior of Gear Noise.
A meaningful discussion about noise is quite difficult because the impression of "noise" is quite subjective. Everybody has a lifetime experience with sound / noise and sees themselves as an expert.
If you want to find the secrets of the universe, think in terms of energy, frequency and vibration. â€” Nikola Tesla
Stringent NVH requirements, higher loads and the trend towards miniaturization to save weight and space are forcing transmission gear designers to increasingly tighten the surface finish, bore size and bore-to-face perpendicularity tolerances on the bores of transmission gears.
In the hypercompetitive race to increase automobile efficiency, Metaldyne has been developing its balance shaft module line with Victrex PEEK polymer in place of metal gears. The collaborative product development resulted in significant reductions in inertia, weight and power consumption, as well as improvement in noise, vibration and harshness (NVH) performance.
NVH â€” noise, vibration and harshness â€” is a key issue in the design and development of modern transmission and driveline systems.
I have outsourced gear macrogeometry due to lack of resources. Now I received the output from them and one of the gears is with â€”0.8Ã— module correction factor for m = 1.8 mm gear. Since bending root stress and specific slide is at par with specification, but negative correction factor â€”0.8Ã— module â€” is quite high â€” how will it influence NVH behavior/transmission error? SAP and TIF are very close to 0.05 mm; how will that influence the manufacturing/cost?
News Items About NVH
1 SMT Offers Engineering Services NVH Capability Webinar (July 29, 2020)
SMT presents the webinar “SMT Engineering Services NVH Capability,” on August 12, 2020 from 8:00 – 9:00 AM EDT. This we... Read News