Search Results

In an electric vehicle, internal combustion engines are replaced by the electric motor. As a result, the signature of source vibration changes. The noise, vibration and harshness (NVH) issues are entirely different in electric vehicle (EV) compared to internal combustion engine (ICE) due to the change in source vibration. The outline of this paper is a comparative study of source vibration, the challenges to address various noise issues related to source vibration and the isolation methodology. A case study is presented to show the different methods of treatment required to mitigate source vibration issues during the electric vehicle development program. Keywords: Engine, Motor, vibration

In electric vehicles, the powertrain mounting system design has challenges different from conventional internal combustion engine (ICE) powertrains. Due to the absence of source noise, the customer predominantly experiences the buzz, squeak and rattle (BSR) noise. The 6 degrees of freedom (DOF) modal frequency target is less stringent than a three-cylinder or four-cylinder ICE powertrain. The durability loads in EV also differ due to less powertrain weight. In this paper, a study has been carried out about balancing all three main performance parameters of modal decoupling, BSR and durability through powertrain mount design optimization. The article shows that a carryover ICE powertrain mount has typical issues in Electric Vehicle (EV). A case study has discussed in detail how to manage those issues. Finally, it is concluded that a particular focus is required during an early stage of mount design to address these challenges for an EV.

For a modified electric vehicle on the same internal combustion engine (ICE) platform, the primary consideration is to have no change in long member and pendulum type conventional engine mounting system to save development cost and timeline. Electric vehicle (EV) powertrain is comparatively lighter w.r.t the ICE. As a result, the engine mount’s static preload setting point or powertrain centre of gravity under static powertrain load gets changed resulting in a change in stiffness for the same engine mount. As the static stiffness changes, the dynamic stiffness and modal frequency also change. The 6 degrees of freedom (DOF) modal frequency has almost no impact on powertrain modes as EV powertrain modes, mainly, the motor frequency, is much higher than engine mount Eigen modes. In this scenario, the gap management gets disturbed due to less static preload, and non-linearity gets affected.

There are two types of EV (electric vehicle) currently in use, namely modified EV and dedicated EV. Generally, we use a modified EV in cost-sensitive markets where we can commonize platform between internal combustion engine (ICE) and EV vehicles. For modified EV, we use the cradle to support the powertrain components, which connects to the engine mount, which in turn attaches to extended members and subframe. The fabricated cradle has many welding components that cause dimensional variation at the rear-mount attachment point on gearbox, which creates a reduction in the dynamic envelops significantly. The decrease in clearance often results in BSR noise, which we have simulated in the rig as well as on rope track. On a rough road, this noise is predominant. This buzz, squeak and rattle (BSR) noise also results in Tip in/Tip out noise, which is quite uncomfortable for the customer during sudden acceleration and deceleration.

Electric vehicles (EV’s) are very much noise, vibration and harshness (NVH) sensitive due to the absence of engine noise. The outline of this paper is based on vehicle level turning noise evaluation. The impact of the driveshaft angle in the frequency range of 1000-2000Hz. The level of noise while turning at driver and co-driver side is evaluated first. Then the possible countermeasure to address such noise issues are also discussed. The impact on the angular adjusted roller (AAR) joint and driveshaft angle is studied along with the impact on other parameters like powertrain mount stiffness, ground clearance and vehicle architecture.