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The growing demand of fuel and cost saving on vehicle, today’s vehicle manufacturer are working on various weight reduction initiative in EV. Lighter weight vehicle have bigger challenges to meet NVH requirement. There are two types of EV called modified and adopted EV’s are commonly in use. The sub frame type of EV system comes under the category of modified EV. In this paper, a mounting system is studied and compared for a cradle type EV as well as sub frame or saddle type EV. MATLAB based optimization tools are used for parameter optimization. The focus is put on the optimization of mounting system location and stiffness for energy optimization, CoG and TRA-EA optimization. The best engine mounting system is compared and adopted based on simulation. 12 DOF studied to address high frequency resonance issues for a sub frame type EV. Finally robustness of the system is checked based on various simulation and optimization.

Today, noise perceived by the occupants is becoming an important factor driving the design standards for the design of most of the interior assemblies in an automotive vehicle. Buzz, Squeak and Rattle (BSR) is a major contributor towards the perceived noise of annoyance to the vehicle occupants. An automotive vehicle consists of many chassis assemblies which are the potential sources of BSR noise. The potential locations of critical BSR noise could be contained within such assemblies as well as across their boundaries. Engine mount design is major area where BSR noises can be heard inside cabin on various road conditions. Natural rubber is regular rubber used in engine mount applications but in this paper BSR problems are solved by changing the rubber compound i.e., NR+BR (slippery compound). Detailed case study is presented where slippery rubber compound is used which is solving BSR issue and also meeting durability targets.

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.

The primary function of an engine mounting bracket is to support the powertrain system in all road conditions without any failure. The mount has to withstand different road conditions and driving maneuvers which exert loads on it. Also, it is challenging to change the mounting locations and types after the engine is built; hence it is paramount to verify the mounting brackets against all abuse loads in the design stage. The Car manufacturers ensure engine mount bracket design meets CAE's (Computer-aided engineering) static and fatigue load cases. The CAE is performed using digital RLD (Road load data) loads. The design checks cumulative strain or stress against specified service life requirements during break and fatigue FOS (Factor of safety) calculations. However, it is difficult to simulate the material's fracture toughness to estimate the effect of the impact load on the mounting bracket.

Powertrain mounts locations and stiffness in vehicle plays very important role in improving vehicle noise and vibration, which is caused by engine firing forces and road disturbances. Once locations are finalized, based on initial calculation and packaging then it is very much critical to play with mount stiffness to achieve required NVH level in vehicle. This paper describes the effect of mount stiffness on the bolted joint integrity. Stiffness fine tuning is done to improve vehicle level NVH and various iteration are done with change in stiffness values of A, B and C mounts. When stiffness specifications are finalized, it is recommended to acquire road load data on the finalized stiffness mount and check for bolted joint integrity since load signature is varying significantly on mount w.r.t stiffness change. If we change mount stiffness value from 128N/mm to 98N/mm, then loads on particular mount is getting increased from 4.5KN to 6.5KN in one of the track testing.

As we are moving towards complete electrification from combustion engine to electric motor, the system design approach also changes due to application. For a range of 100-150 kg EV powertrain weight, number of mounts as well as mount locations, orientations and stiffnesses plays a significant role during system design. The electric powertrains are usually lighter and their mounts are usually stiffer than the mounts for typical combustion engines, the static displacements at dead load are usually lower. However, currently it seems like there is no common direction of all OEM’s regarding the question of how stiff an e-motor mounting system should actually be. Due to the high torque of the EV’s one could even think about switching to a four point mounting instead of a pendulum mounting.