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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.

Durability is an important indicator to measure the automobile quality and reliability. Automotive industry is striving to develop products having excellent performance to weight ratios and along with high safety standards. A successful product should have adequate robustness during normal customer operation and the ability to withstand high impact events without impairment of function or safety relevant damage. Road Load Data Acquisition (RLDA) along with efficient design and validation processes are, among others, critical factors for success in the automotive industry. Physical RLDA is expensive and time consuming, the prototype vehicles being costly and only available at a later stage in the vehicle development cycle. Component failures occurring on the proto test vehicles can prove to be a major setback, delaying the product launch by months. In order to overcome above challenge, this paper presents an innovative methodology to carry out Digital RLDA (dRLDA).

In the highly competitive global automotive market and with the taste of customer becoming more refined, the need to develop high quality products and achieve product excellence in all areas to obtain market leadership is critical. Buzz, squeak and rattle (BSR) is the automotive industry term for the audible engineering challenges faced by all vehicle and component engineers. Minimizing BSR is of paramount importance when designing vehicle components and whole vehicle assemblies. Focus on BSR issues for an automobile interior component design have rapidly increased due to customer’s expectation for high quality vehicles. Also, due to advances in the reduction of vehicle interior and exterior noise, engine mounts have recently been brought to the forefront to meet the vehicle interior sound level targets. Engine mounts serve two principal functions in a vehicle, vibration isolation and engine support.

Normal engine mounting system is designed to carry loads of powertrain in all driving conditions and also isolate the vibrations of powertrain. Softer mounts are good for vibration isolation but it is not recommended to have softer mounts because durability will be affected adversely. Optimum stiffness needs to be finalized which will have balance between durability and performance. In addition to durability many performance parameters needs to be checked during the time of development. This study includes the development of engine mounting system for elimination of drive away judder in first gear. Maximum peak torque value for the drive-away event is in the range of 80Nm - 120Nm. In the worst case, this peak torque can reach to maximum 170Nm depending on maneuver, engine rpm is around 1100-1200. Steering wheel, instrument panel and whole vehicle cabin will vibrate for few seconds and then vehicle will run smoothly.

The recent vehicle development demands for electric powertrain as against conventional fuels engines. The electric powertrain offers advantages in terms of cleaner and quieter operations. In electric vehicle, the conventional engine is replaced by electric motor operated on batteries. Here, the conventional engine refers to those powered by diesel, petrol, CNG and some hybrid vehicles using fuel as primary source for power generation. Thus, the system design approach for mount also changes. At present, various approaches are being followed to mount electric powertrain like conventional pendulum type, with or without cradle, Common or different motor and electric box mountings etc. The electric powertrain differs from conventional powertrain in terms of weights, mass moment of inertia, torque, NVH requirements like Key in Key off, idling, low frequency vibrations etc. Thus conventional mount will not necessarily meet NVH requirements for Electric powertrains.

Engine mounting system maintains the position of powertrain in the vehicle with respect to chassis and other accessories during inertia, torque reaction loads and roadway disturbances. The mounting system also plays a role in terms of isolation of the rest of the vehicle and its occupants from powertrain and helps in maintaining vehicle ride and handling condition. This paper investigates the performance comparison between hydromount and switchable hydromount during idle and ride performance. The optimization scheme aims to improve the performance of the mounting system in order to achieve overall powertrain performance and NVH attribute balancing through switchable mount technology.

Sustainable development is a very complex concept involving several inter-related issues and concerns. Globalization has given a new dimension to social, economic and environmental development associated with the perceived responsibilities and growth indicators. Both developing and developed countries have the opportunities to exploit comparative advantages in the changing economic, social and environmental scenario while targeting sustainable growth together with expansion of the business prospects. Every region perceives these opportunities with different notion. There is a plethora of indicators for assessing sustainability. However, assessment criteria, prioritization and trade off for a given sustainability parameter against the other could be very complex while evolving transport growth model in emerging economies.

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.

NVH refinement of passenger vehicle is very much essential to level that customer did not find any irritation. Engine mounting selection and design is critical to achieve targeted NVH performance. Most of OEM’s are using properly tuned hydromount to have best idling NVH performance. Hydro-mount design should be tuned at problematic frequency where we can get the very low dynamic stiffness and can get the required performance. Hydromount should be designed carefully otherwise there will be abnormal noise due to cavitation effect. Cavitation noise is such a noise which is very difficult to identify that it is coming from mount. Cavitation is the formation and collapse of vapor bubbles in a working fluid when local static pressure falls below the vapor pressure of the working fluid. Systematic approach is presented in this paper to detect cavitation noise from hydraulic mount and how to overcome the same.

If we see from the past and now competition in automotive industry increased tremendously and every car manufacturer are bringing up there innovations into the market and giving a lot of options to the customers to choose and the customer experience as well as satisfaction has become one of the main driver of success for the company. In today’s world of automotive design virtual analysis is playing a crucial role in the design and development. There are software’s that are available in market to simulate practical conditions digitally. Here we are mainly focused on effect of change in engine mount stiffness on acceleration at driver seat rail point using ADAMS. Which facilitates reduction of design of experiments and finalizing optimized stiffness values for engine mounts for engine idle vibration refinement point of view. ADAMS is mechanical system analysis software where we can simulate the dynamic behavior and distribution of loads throughout the system.

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.

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.

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.

The torque required to tighten any threaded joint is different from the necessary torque to untighten threaded bolt or nut, and it is not observed or widely known since this is a regular and straightforward operation. Typically the torque needed to untighten a newly tightened clamp is around 10% to 30% less than the torque to stretch it further. During tightening a threaded bolt, a significant amount of torque required to overcome friction in the threads and under the nut face. The proportion of the torque used to overcome frictional resistance depends upon the friction value. When we tighten a joint with a coefficient of friction of 0.12, only about approximately 14% of the torque required to stretch the fastener producing the clamp load with 86% of the torque is lost overcoming friction. The torque needed to pull the bolt always acts in the untightening direction, resulted in untightening torque lags behind the tightening torque.

Key on/off Vibrations plays an important role in the quality of NVH on a vehicle. Hence having a good KOKO in the vehicle is desirable by every OEM. The vibration transfer to the vehicle can be refined by either reducing the source vibrations or improving isolation. In this study, critical factors affecting KOKO vibration has been identified. Focus has been given on improving the KOKO by change in mounting system stiffness & stopper gap, and assuming other parameters as constant. The study highlights a new simulation approach using ADAMS View to help run a DOE for solving KOKO issue on vehicle. The contribution of C mount stiffness and stopper gap is shown through simulation results. The correlation between simulation & test results has been established by measuring rigid body modes and KOKO vibration on vehicle for a set of mount configuration. Test results show significant KOKO improvement with the mount configuration optimized through simulation.

Vehicle lateral shake during take-off is sensitively felt by customers when the vehicle is driven at a low speed under drive away acceleration. The take-off shudder is complained by customers during 1st and 2nd gear take off. Under an engine torque and half shaft angle, the drive-away shudder usually occurs during acceleration to a specific low speed at 1200 to 1600 engine rpm, which makes the vehicle shake severely. A thorough investigation with possible design optimization of mounting system, drive shaft joint and lubrication is done to reduce the lateral vibration. This paper focuses on a passenger car, the take-off shudder of which occurs at a speed between 20 km/h and 30 km/h. The test vehicle is a monocoque construction with front wheel drive east west engine. Vehicle lateral shake is observed during the low gear power train run up in Wide Open Throttle (WOT) condition.

Clutch engagement judder is a phenomenon wherein the driver experiences vibrations on seat during the clutch engagement process for the vehicle launch. Clutch engagement judder is one of the critical vehicle attributes as a part of overall vehicle NHV. Torsional oscillations, specifically originating from clutch in the driveline during clutch engagement, are referred as clutch engagement judder. Judder is a phenomenon wherein friction induced torsional vibrations are generated in the driveline because of sliding contact between clutch and flywheel, during engagement. These resulting oscillations inherit the first resonance frequency of the driveline. The engagement judder not only affects the dynamics of transmission system but also the vehicle, because of excitations being transferred to body via suspensions and mounts. Passengers experience these oscillations as vibrations during vehicle launch. If excitation level is high then it may cause discomfort to passengers.

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.

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.