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For the thermal management of an automobile, the induced airflow becomes necessary to enable the sufficient heat transfer with ambient. In this way, the components work within the designed temperature limit. It is the engine-cooling fan that enables the induced airflow. There are two types of engine-cooling fan, one that is driven by engine itself and the other one is electrically driven. Due to ease in handling, reduced power consumption, improved emission condition, electrically operated fan is becoming increasingly popular compared to engine driven fan. The prime mover for electric engine cooling fan is DC motor. Malfunction of DC motor due to overheating will lead to engine over heat, Poor HVAC performance, overheating of other critical components in engine bay. Based upon the real world driving condition, 1D transient thermal model of engine cooling fan motor is developed. This transient model is able to predict the temperature of rotor and casing with and without holes.

Effective 1st April 2023, India's automotive emissions regulation has shifted from BS-VI Stage-1 to BS-VI Stage-2 standard the after-treatment systems need to demonstrate robust performance not just on the cycle, but also to demonstrate emissions for on-road Real Driving Emission (RDE) conditions. A stringent On-Board Diagnostics (OBD) strategy to monitor the real-time emission levels along with compliance Road Driving Emissions (RDEs) are focus areas for BS VI Stage-2 emission legislation. The maximum speed on MIDC is 90km/h in BS-VI Stage-1, Diesel Oxidation Catalyst (DOC)+Selective Catalyst Reduction Filter (SCRF®) was able to meet legislation at the lab, and now with the RDE cycle max speed of the vehicles under the M1 category <3.5 T will have the max permitted legal limit shall surpass 100 km/h for not around 3% of the span in the third phase of driving cycle for which max speed is up to 120 km/h.

In this current fast-paced world, releasing a defect free product on time is of utmost importance in the automotive domain. The automobile powertrain is designed with a fine balance of weight and power. Clutch, an intermediate part between engine & transmission in manual transmission vehicle plays crucial role for vehicle smooth drive & functionality. Hydraulic clutch slave cylinder (CSC) which is a part of clutch release system was observed with one failure mode in one of the vehicles during internal road validation. It facilitates to actuate the clutch diaphragm in order to disengage the clutch when clutch pedal is pressed and to re-engage the clutch back when the clutch pedal is released. CSC failure directly disconnects the response of leg to clutch and thus driver may lose vehicle control and can possibly cause a severe vehicle crash.

Wheel rim is one of the most critical safety parts in a vehicle. Strength in cornering loading is one of the most important durability test requirements for automotive steel wheel rim apart from other loading conditions like vertical and impact loads. Based on the category of vehicle and customer usage pattern, the accelerated cornering test is derived for testing steel wheel rims. The simulation and certification of steel wheel rim for the required dynamic durability testing requirement involves many steps ranging from acceptance criteria derivation to reliably addressing known potential failure zones in steel wheel rims. Nave radius and crown are sensitive to cornering loads, given the pitch circle diameter at the concept stage, the known effects of these key parameters are determined from DOE and used as reliable indicators to arrive at the shape and section of the steel wheel rim.

One of the most essential components of automotive HVAC system is compressor. In a vehicle it is directly mounted on the engine. It derives power from the engine feed system to keep refrigerant moving in the HVAC system of the vehicle. It is also essential to complete the vapor compression cycle. During the operation, it causes considerable load on the engine and thus results in lower fuel efficiency and higher pollution. There are several types of compressors available globally. According to construction it can be classified as reciprocating piston type, scroll type and rotary vane type. The reciprocating piston types of compressors are further classified as fixed displacement and variable displacement. Normally the fixed displacement compressors have good idling cooling performance, but it increases the load on the engine. To reduce the load on the engine and to have good idling cooling performance, generally a variable displacement compressor is used.

BS6.1 emission standards were implemented in India in 2020 followed by BS6.2 which added more controls on emission limits. For BS6.2 OBD (On Board Diagnostics) and RDE (Real Driving Emission) were added on to the existing BS6.1 emissions. Emission control changes usually need addition of new parts, calibration changes and durability requirements. For the current 1.5L, 3-cylinder diesel engine an pSCR (Passive Selective Catalytic Reduction) brick was added for control of NOx for meeting RDE. For meeting OBD requirements PM (Particulate Matter) and NOx sensors were added in the cold end pipe along with calibration changes to meet the BS6.2 norms. In this paper we will discuss on the design aspects of sensors and pSCR only. The sensor and pSCR positioning plays vital role in meeting the legislative requirements and to ensure the ease of assembly and durability of the parts.

Precise control over mixture formation withhigh fuel pressure and multiple injections allows Gasoline Direct Injection (GDI) engines to be operated satisfactorily at extreme conditions wherePort Fuel Injection (PFI) engines wouldnormally struggle due to combustion instability issues. Catalyst heating phase is one such important condition which is initiated after a cold engine start to improve the effectiveness of the three-way catalyst (TWC). For a given TWC specification, fast light-offof TWC is achieved in the catalyst heating phase by increasing the exhaust gas temperature with higher exhaust mass flow. The duration of this phase must be as short as possible, as it is a trade-off between achieving sufficient TWC light off performance and fuel efficiency.

In vehicle Front End Flow (FEF) analysis, the basic objective is to predict the mass flow/velocity of air at radiator inlet with constant fan rotation. In general, the Multiple Reference Frame (MRF) model is used to model the fan. The flow velocity distribution at radiator inlet due to fan rotation should be uniform in circumferential direction whereas, it should vary in radial direction depending upon the blade geometry. However, the drawback with MRF model is that, it gives higher velocities near radiator inlet at regions corresponding to the fan blades and lower velocities at other regions, which is not realistic. This issue is more predominant when the vehicle is at low speeds or when radiator is placed at mid or back of the vehicle or the fan is having less number of blades. In order to nullify this uneven velocity distribution at radiator inlet, Mixing Plane (MP) approach was used in addition to the MRF model.

Commercial transportation is the key pillar of any growing economy. Light and Small commercial vehicles are increasing every day to cater the logistics demand, but there is always a gap between customer’s actual and desired operational efficiency. This is because of lack of organized fleet and efficient fleet operation. The major requirement of fleet owners is timely delivery, high productivity, downtime reduction, real time tracking, etc., Automakers are now providing fleet management application in modern LCV & SCV to satisfy the fleet operator requirement. However, any feature malfunction, consignment mismatch, wrong notification, missed alerts, etc., can incur huge loss to fleet operator and disrupt the entire supply chain. Hence it is very critical to extensively validate the telematics features in fleet management application. This paper explains the approach for exhaustive validation strategy of fleet management applications (B2B) from end user perspective.

The inherent capacity of electric motors to generate substantial instant torque can lead to significant load reversals in electric vehicle driveshafts under specific road conditions and driving maneuvers, highlighting the need for targeted improvements in driveshaft design, particularly in optimizing joint sizing. This paper presents a systematic approach to investigate the root causes of a catastrophic driveshaft failure that occurred during specific vehicle tests on a road with multiple speed bumps, resulting in numerous high torque reversals. The objective was to enhance system robustness through changes in driveshaft design and the manufacturing process, coupled with a software calibration technique to reduce torque demands under such operating conditions. The process encompassed torque measurements at the vehicle level, failure replication on a test rig, and correlation with simulations.

As the world rapidly moves from IC engine powered vehicles to the ‘more sustainable’ electrified vehicles, the Powertrain Mounting System needs to be re-engineered to meet refinement requirements of customer. Electric vehicles are quieter but due to lack of the “masking effect”, are sensitive to minor disturbances that are perceived to be objectionable by passengers. Also, E-powertrains are lighter, produce higher torque at low rpms & operate at higher rpms which calls for different countermeasures for mounting systems compared to conventional single isolation 3-point mounting system as used in IC engines. Double isolation mounting system, where powertrain is connected to an auxiliary mass (sub frame/cradle) via mounts, which is suspended to the vehicle body via subframe bushes results in 12 rigid body modes, 6 for each mass, is highly effective in lowering the transmission of vibration at high frequencies.

In the recent past a lot of emphasis is given for the overall weight reduction of the sound package used in the vehicles. The paper presents a study of one of such materials used in the automotive market. The dash panel is a primary area for the engine noise transmission to the cabin. Hence the material selection of the dash inner acoustic insulation is critical. In the conventional method a barrier (EVA) and a decoupler (foam) is used. In the conventional design the surface weight of the barrier has to be substantially high for the dash insulation to perform effectively and hence adds to more weight. In the present application of light weight material also known as dual density absorbers and barrier is used for the dash acoustic insulator. The study reveals the good acoustic performance of the light weight dash mat in terms of passenger cabin noise reduction and improved sound quality along with weight reduction.

Vibrational fatigue is a metal fatigue caused by the forced vibrations which are purely random in nature. The phenomenon is predominantly important for the components/systems which are subjected to extreme vibration during its operation. In a vehicle, an engine is the main source of vibration. The vibrational fatigue, therefore, plays a key role in the deterioration of engine mounted components. Multiple test standards and methodologies are available for validating engine mounted parts of an automobile. These might not be appropriate in the case of an off- road vehicle as the vibrational exposure of engine mounted components of an off-road vehicle is entirely different. In the case of an off-road vehicle, the engine mounted components are subjected to a comparatively higher level of vibration for a longer duration of time as compared to the passenger cars.

The paper talks about machining techniques and solution approaches while machining Aluminium grade gearbox housings. Mahindra’s next generation gearbox housings are made totally of Aluminium; along with the higher strength to weight ratio that comes with using Aluminium come highly optimized ribbed structures that aid in achieving the said strength. While machining such Aluminium structures, it is imperative that the clamping forces do not load the component in ways it is not intended to. The paper talks about finish machining and proving out a semi-finished gearbox housing set (front, intermediate plate and rear) on a conventional Horizontal Machining Center (HMC). The input to the machine is the semi-finish housing that is already machined before with stock for finish operations.

In the current automobile era, weight, emission, and fuel efficiency were driving the overall powertrain development without compromising on the performance. Due to light weight and high-performance engines, the increased level of excitations in terms of torsional, axial, and bending frequency on crank shaft during combustion is inevitable. The axial and bending moment exerted from crankshaft during combustion causes vibration of the clutch diaphragm spring, in turn these vibrations are transferred through the hydraulic release system to clutch pedal which induces undesirable pedal pulsation and vibration during clutch pedal operation. The subjective perception on Noise Vibration and Harshness (NVH) becomes more essential in the Vehicle development process of modern high-performance vehicles.

Reducing the vibrations in the powertrain is one of the prime necessities in today's automobiles from NVH and strength perspectives. The necessity of 4×4 powertrain is increasing for better control on normal road and off-road vehicles. This leads to bulky powertrains. The vehicle speeds are increasing, that requires engines to run at higher speeds. Also to save on material costs and improve on fuel economy there is a need for optimizing the mass of the engine/vehicle. The reduced stiffness and higher speeds lead to increased noise and vibrations. One more challenge a powertrain design engineer has to face during design of its transmission housings is the bending / torsional mode vibrations of powertrain assembly. This aggravates other concerns such as shift lever vibrations, shift lever rattle, rise in in-cab noise, generation of boom noise at certain speeds, etc. Hence, reducing vibrations becomes an important and difficult aspect in design of an automobile.

Electric vehicles (EV) are much quieter than IC engine powered vehicles due to less mechanical components and absence of combustion. The lower cabin noise in electric vehicles make customers sensitive to even small noise disturbances in vehicle. Road boom noise is one of such major concerns to which the customers are sensitive in electric vehicles. The test vehicle is a front wheel driven compact SUV powered by electric motor. On normal plain road, noise levels are acceptable but when the vehicle has been driven on coarse road, the boom noise is perceived, and the levels are objectionable. Multi reference Transfer Path Analysis (MTPA) is conducted to identify the path through which maximum forces are entering the body. Based on MTPA, modifications are proposed on the suspension bushes and the noise levels were assessed.

With the advent of stricter emission norms such as Bharat Stage VI - Phase I and II, the design of the exhaust after treatment system becomes crucial for the internal combustion engine. Inadvertently, the size of the after-treatment system also becomes bigger to cater to the latest emission norms, which leads to increased resistance to the flow of exhaust gases through them. However, the resultant back pressure generated in these devices deteriorates the engine performance. Hence, the onus is on the engine designer to design the after-treatment system and the bracketing concept for mounting in such a way that the engine performance remains intact, and the entire system is packaged within the vehicle boundary conditions. The after-treatment system experiences severe vibrational loads as well as thermal loads.

A differential casing is one of the important elements in the vehicle power train, whose objective is to house differential gears and take different loads coming from these gears. The function of a differential is to drive a pair of wheels while allowing them to rotate at different speeds. While taking a turn, the outer wheel needs to travel more compared to the inner wheel. This is possible due to the differential which rotates them at different speeds. This Paper highlights a simplified methodology to capture the differential casing failure and to resolve the same. The methodology adopted was then correlated with the test measurements to increase the confidence. During physical tests, strains are measured at different orientations of the differential casing and correlated with simulation results.

The customer of today is sensitive towards shift quality. The demand is for a crisp and precise gear shift with low shift effort. The impulses from synchronizers make shifts feel notchy. After synchronization the blocker ring releases the sleeve. The sleeve then hits the teeth of the clutch body ring. The second impulse causes a phenomenon called double bump. This can be felt at the hand and makes a shift feel notchy or sluggish. An ideal way to overcome this is to optimize the detent profile. This paper explains in detail the various factors that contribute to the perceived shift feel. Various methods to optimize the forces on the knob by changing the detent profile are discussed. Gear Shift Quality Assessment (referred as GSQA henceforth) is a tool to acquire the required shift feel data. Using this tool shift efforts and kinematics of a 5 speed manual transmission are plotted for illustration. The calculations required to optimize the detent profile are explained in detail.