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Direction Specific Analysis of Psychoacoustics Parameters Inside Car Cockpits: a Novel Tool for NVH and Sound Quality

University of Parma-Daniel Pinardi, Costante Belicchi, Angelo Farina, Marco Binelli
University of Parma / ASK Industries SpA-Lorenzo Ebri
  • Technical Paper
  • 2020-01-1547
To be published on 2020-06-03 by SAE International in United States
Psychoacoustics parameters are widely employed in automotive field for objective evaluation of Sound Quality of vehicle cabins and their components. The standard approach relies on binaural recordings from which numerical values and curves are calculated and head-locked binaural listening playback can be performed. Recently, the Virtual Reality technology started to diffuse also in automotive field, bringing new possibilities for enhanced and immersive listening sessions. In this paper, we combine both solutions: the VR approach is adopted to calculate the principal psychoacoustics parameters. The acquisition system consists in a massive spherical microphone array featuring a camera for recording panoramic visual background. The acoustical information is encoded into High Order Ambisonics spatial format, that can be rendered on stereoscopic visors and Spatial PCM Sampling format that can be used to produce 360° colour maps. In this way, we are able to plot the psychoacoustics parameters adding their directivity information over the panoramic background, turning the array into a novel 360° diagnostic tool. At the same time, the playback can be performed inside Ambisonics listening rooms or binaurally…
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Study of the Noise Contributors on the Interior Acoustic of a Car and Their Countermeasures

Autoneum Holding AG-Thibault Lafont, Claudio Bertolini
Saint-Gobain-Fabien Dalzin, Fabien Bouillet
  • Technical Paper
  • 2020-01-1585
To be published on 2020-06-03 by SAE International in United States
This paper shows that the collaboration between a glass manufacturer and a passive acoustic treatment manufacturer can bring different benefits and considerably improve the interior acoustics of a vehicle. In terms of passenger safety and well-being, glazing have always played a key role by offering solutions to interior comfort, particularly when it comes to heat and acoustics. Today, cars are becoming a living space which from an acoustic point of view brings a challenge for the interior comfort. Indeed, glazing has no absorption and classically it has an acoustic insulation weakness around its coincident frequency. In most of the cases, these different aspects make glazing one of the main contributors to the sound pressure level in the passenger compartment, and the trend is not one of change. However, there are possible countermeasures. One of which is the use of laminated glazing with acoustic PVB. This solution allows to reduce the loss of insulation performance at the coincidence frequency. The other is the usage of passive interior acoustic trims. When properly positioned and optimized, the latter…
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Innovative Rear Air Blower Design Application for Improving Cabin Thermal Comfort with improved Air Distribution and Air Quality.

Subros Ltd-Ravi Garg, Suraj maske, Yogendra Singh Kushwah
  • Technical Paper
  • 2020-28-0034
To be published on 2020-04-30 by SAE International in United States
In recent times, overall thermal comfort and air quality requirement have increased for vehicle cabin by multifold. To achieve increased thermal comfort requirements, multiple design innovation has happened to improve HVAC performance. Most of the advance and add on features like Multizone HVAC, dedicated rear HVAC, Automatic climate control, Advance Air filters, and Ionizers etc lead to increase in cost, power consumption, weight, and integration issues. Besides this in the vehicle with only front HVAC, airflow is not enough to meet rear side comfort for many cars in the B/C/SUV segment. This study aims to analyze the various parameters responsible for human thermal comfort inside a car with the focus on lightweight, low power consumption, compact Rear Blower to make passengers more comfortable by providing optimum airflow inline of mean radiant temperatures and cabin air temperature. The new design of Rear blower external surfaces has a set of air modifier surfaces in the direction of flow outlet. The second set of air modifier surfaces & an air deflator portion provided just upstream of outlet portion.…
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Experimental analysis of HVAC system level noise in mobile air conditioning (MAC) system

Tata Motors Ltd-Prasanna V Nagarhalli, Uttam Titave
Tata Motors, Ltd.-Anurag Maurya
  • Technical Paper
  • 2020-28-0035
To be published on 2020-04-30 by SAE International in United States
With the advent of new technologies and rigorous research and development in engines, cars are becoming quieter than ever. This has led to the noises which were earlier, masked behind engine noise being audible inside the passenger compartment. Having a quieter air-conditioning (AC) system would aid us in cutting down on this parasitic noise source. Making it one of the important parameters during the design and development of the Heating, Ventilation and Air-Conditioning (HVAC) system for a vehicle program. However, due to packaging constraints improper integration or selection of different AC parts, there is a possibility that the noise generated from the AC compressor to get amplified while the refrigerant flows through the thermal expansion valve (TXV) or through pipes. This is because the pressure pulsation, in the refrigerant flow, travels along the pipes and can amplify the noise if it is not properly dampen out. Also, TXVs can also be a source for noise if the quality of refrigerant - dryness fraction - is not optimized at the entry. The objective of the current…
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A detailed study of prominent factors affecting evaporator frosting in a mobile air conditioning (MAC) system

Tata Motors Ltd-Prasanna V Nagarhalli, Shrikant M Awate, Mubeen Syed
Tata Motors, Ltd.-Anurag Maurya
  • Technical Paper
  • 2020-28-0014
To be published on 2020-04-30 by SAE International in United States
In an automotive air conditioning system, evaporator is well designed for effective heat transfer between refrigerant and air flowing over the evaporator. Hence, the better cooling and dehumidifying the incoming air. Sometimes, at the low ambient temperature and higher relative humidity conditions a frost is observed. It is accumulated over the evaporator and often become thicker enough to block the flow of air completely passing through the evaporator resulting in a rise in vehicle cabin temperature. Current work presents the probable causes of frost formation and their effects on the performance of evaporator and hence, the performance of the automotive air conditioning system. There are four major factors, thermistor poor response, undercharged and overcharged system, clogged air-filter, and also the type of compressor causing frost formation over the evaporator are considered for analysis. Current work presents the experimental analysis of the evaporator performance in the low ambient conditions with the above factors in different iterations. With the above analysis new methods and guidelines can be generated in order to avoid frost formation over the evaporator.
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Challenges to incorporate cabin air quality enhancer in mobility solutions

Tata Motors Ltd-Sambhaji Jaybhay, Balkrishna Gavhane, Sangeet Kapoor
Tata Motors, Ltd.-Shubham Vijay Nimsatkar
  • Technical Paper
  • 2020-28-0016
To be published on 2020-04-30 by SAE International in United States
In the past five years, Indian cities have been consistently appearing in the list of top 15 world’s most polluted cities. A common man in India, daily spend more than 2 hours on the road during commute to work, thus exposed to inhale highly polluted air. In case of passenger car users, he/she is exposed to ~ 6 times more polluted air compared to ambient air – as vehicle cabin is a closed space where the air recirculates through air conditioning (AC). Prolonged exposure to such polluted air shows increasing trend in respiratory illnesses, breathing discomfort and fatigue. This paper discusses about the key challenges involved in incorporating cabin air quality enhancer (cabin air filters) in mobility solution. Engineering challenges are packaging of cabin air filters in current vehicle cabin and its validation through objective assessment and subjective assessment by trained evaluator. The objective assessment comprises of bench tests and subjective assessment requires trained expert noses, hence it is a business of high development expense. Ultimately, this development cost will be borne by customer through…
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A Case Study on Reducing the Fuel Pulse Noise from Gasoline Engine Injectors

FCA US LLC-Weiguo Zhang, Toon Tan, John Malicki, Glenn Whitehead
  • Technical Paper
  • 2020-01-1276
To be published on 2020-04-14 by SAE International in United States
Vehicle NVH performance is a very important consideration for vehicle buyers in the marketplace. There are many noise sources from the fuel system to generate noise in a vehicle. Among them, the pressure pulsations due to the rapid opening and closing of gasoline engine injectors can cause undesirable fuel pulse noise inside the vehicle cabin. As the pressure pulsation propagates in the fuel supply line toward to rear end of the vehicle, the pressure energy is transferred from fuel lines to the vehicle underbody through clips and into the passenger compartment. It is crucial to attenuate the pressure pulsation inside the fuel line to reduce the fuel pulse noise. In this paper, a case study on developing an effective countermeasure to reduce the objectionable fuel pulse noise of a V8 gasoline injection system is presented. First, the initial interior noise of a prototype vehicle was tested and the objectionable fuel pulse noise was exhibited. The problem frequency ranges with pulse and ticking noise content were identified. Several test iterations on root causing analysis and countermeasures…
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A Control System for Maintaining Passenger Cabin Air Quality

Chulalongkorn University-Thanin Wangsawangkul, Thiti Maneepipat, Nattapong Sukumdhanakul, Porpin Pungetmongkol, Prabhath De Silva
DENSO International Thailand-Pradit Mahasaksiri
  • Technical Paper
  • 2020-01-1243
To be published on 2020-04-14 by SAE International in United States
This paper presents a control methodology to maintain vehicle cabin air quality within desirable levels, giving particular attention to gaseous contaminants carbon dioxide (CO2) and carbon monoxide (CO). The CO2 is generated by the occupant exhalation while the CO is assumed to be ingested with the incoming fresh air. The system is able to detect and improve cabin air quality by controlling the recirculation flap of the ventilation system to control the amount of fresh air intake. The methodology is demonstrated in the laboratory using controlled experiments with a production level automotive HVAC (Heating Ventilating and Air-Conditioning) module. The results indicated that the designed control system can work automatically and control the CO and CO2 gas concentrations within acceptable levels.
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A study on the effect of different glasses and its properties on vehicle cabin during soaking at hot ambient conditions using 1D simulation

FCA Engineering India Pvt., Ltd.-Karthik Subramanian, Prakashbabuji Danapalan, Saravanan Sambandan
FCA US LLC-Murali Govindarajalu
  • Technical Paper
  • 2020-01-0956
To be published on 2020-04-14 by SAE International in United States
Increase in traffic conditions and global increase in the ambient temperature during the summer season, heat load in the vehicle cabin is also increasing, creating a huge thermal discomfort for the passengers. There are two scenarios in which these adverse conditions can be a problem, one is when driving the vehicle in traffic condition and another one is when the vehicle is parked in the open sun both during the summer season. While for the first scenario, at least the air conditioner can be switched on, for the soaking scenario the cabin temperature can reach alarming levels which may have serious discomfort and health effects on the human entering vehicle. Although there are options of remote switching on of air conditioners, they are restricted to vehicles having an automatic transmission only. Considering the different parts of cabin, the glasses occupy majority of the portion which is exposed to the sunlight and that transmit the heat directly into the cabin, which in turn is absorbed by different materials resulting in alarming temperature levels in cabin when…
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An Analysis of the Effects of Ventilation on Burn Patterns Resulting from Passenger Compartment Interior Fires

Ford Motor Company-James J. Engle, Jennifer L. Buckman, Jeff Williams, Erich Kemnitz, Eric Kalis
  • Technical Paper
  • 2020-01-0923
To be published on 2020-04-14 by SAE International in United States
Vehicle fire investigators often use the existence of burn patterns and the amount and location of fire damage to determine the fire origin and its cause. The purpose of this paper is to study the effects of ventilation location on the burn patterns and burn damage of passenger compartment fires. Four similar 20XX Ford Fusion vehicles were burned. The fire origin and first material ignited were the same for all four vehicles. In each test, a different door window was down for the duration of the burn test. Each vehicle was allowed to burn until the windshield, back glass, or another window, other than the window used for ventilation, failed, thus changing the ventilation pattern. At that point, the fire was extinguished. Temperatures were measured in the passenger compartment and video and still photography were recorded. Post-burn, the vehicle burn patterns were analyzed and conclusions drawn on: ability to determine a window was open during the fire, which window was open, the effect the open window had on burn patterns and burn damage, and the…