Car Cabin Research Articles

An in-plane flexible ring model for the analysis of the free and forced response of a rolling tyre

The increased demand for vibroacoustic comfort as well as regulations on noise and vibration levels have made the NVH (Noise, Vibration, Harshness) performances of a vehicle to become one of the fundamental design criteria. Therefore, predictive models for the analysis of noise and vibration transmission mechanisms represent interesting tools to support the R&D department of the automotive companies. Focusing the attention on passenger's comfort, the vibrations induced by the tyre/road interaction propagate from the contact area to the hub and finally inside the cockpit through structure-borne transmission paths. This can be regarded as one of the major contributors to the car cabin interior noise at low frequencies (between 20 and 500 Hz). Simplified models able to interpret the waves propagating inside the tyre structure and influenced by the angular speed may support the studies in this research field. To this end, an analytical model based on the theory of the flexible ring on elastic foundation has been developed. It allows analysing the tyre dynamics in both static and rolling conditions. Model parameters have been calibrated based on an Experimental Modal Analysis of the static tyre. The free response of the tyre shows the bifurcation effect at different rolling speeds, while a cleat test simulation has been carried out to investigate the forced response of the tyre.

NVH investigation of automotive HVAC brushless motors

In the automotive industry, thermal systems are of critical importance in securing optimum vehicle operating, preserving battery capacities and ensuring passenger comfort. These systems involve a wide range of components with various technologies, designs and more innovation. Currently, thermal engine market shares are decreasing as facing increasing electrification trends worldwide. Consequently, thermal systems may become major sources of noise and vibration that may emerge inside the car cabin. This may cause significant discomfort to passengers and can create disturbances to passersby outside the car. As a system supplier, Valeo ensures NVH compliance according to internal standards and OEM specifications during development and production stages. However, as electrification trends involve more and more innovations with less technical background, ensuring NVH compliance becomes a formidable challenge to deal with. Among the main NVH sources, the HVAC Brushless motor is highly critical as implanted inside the car cabin. This paper focuses on the main NVH topics encountered on HVAC BLDC motors. First, the NVH sources are analyzed from mechanical and magnetic design perspectives. Furthermore, solutions to control the NVH behavior are presented which sets the product's intrinsic limitations and operating conditions. Finally, from a technical compliance perspective, specification design implications are discussed.

音像仰角推定に関する両耳聴モデル改善の基礎検討

In this study, the binaural model for the sound image elevation estimation was extended and experimentally verified under adverse perceptual conditions in a car cabin. First, the relationship between the spectrum of left and right ear input signals and sound image elevation in a simulation of a car cabin environment and in an actual car cabin environment was learned using a neural network. Then, cross validation of the proposed method was conducted under the conditions of a sound field where detection and discrimination of the spectral notches, an important cue for sound source elevation perception, is difficult, and as a result, high generalization performance was obtained. The model was then further extended and its accuracy was again tested in the interior environment of a car with noise. Results verified that the proposed approach exhibited the same trends as the conventional method.

CFD driven prediction of mean radiant temperature inside an automobile cabin using machine learning

The present work describes the effect of various climatic conditions on the thermal environment inside an automobile cabin soaked under direct sunlight. Three-dimensional soaking simulations of the in-cabin flow and heat interactions have been carried out using the commercial solver ANSYS Fluent 18.1. The influence of external climatic conditions has been incorporated into the computations through three parameters, viz. ambient temperature, solar flux, and wind speed. The effects of each of these parameters have been investigated by considering a rich parametric space consisting of different values and combinations of these parameters. The influence of these variables on the thermal environment inside the cabin is described with the help of temperature contours. The MRT at the driver’s location has been evaluated, and its dependence on each of the external climatic parameters is reported. The results from the CFD simulations have been further used to train three supervised machine learning algorithms, viz. linear regression with stochastic gradient descent (LR), random forests (RF), and artificial neural network (ANN) to predict MRT at the driver’s location. The MRT predictions made by these models have also been compared based on the performance metrics such as mean absolute error and Wilcoxon signed-rank test. The machine learning model’s performance has been tested using climatic data of different cities. These results indicated that the machine learning models make predictions above 99% accuracy. This methodology enables MRT estimation without relying on experiments or CFD simulations and subsequently allows better control and automation of automobile air-conditioning systems.

PERANCANGAN TEKANAN UDARA POSITIF PADA KABIN MOBIL MSSC (MOBILE SWAB SAMPLING CHAMBER)

MSSC (Mobile Swab Sampling Chamber) car should have a fulfilling requirement as a protective isolation room or positive pressure room. A positive pressure room is needed so the virus or bacteria that is carried by the patient outside the car could not enter and contaminate the medical officer inside the car. Based on that need, the MSSC car is designed so that it can be used as a swab test sampling and having a positive pressure. The designing process was started by assembling each part of the car cabin that was used as an examination tool and positive pressure maker. This design was then simulated using the CFD method to find out whether the car cabin design produces positive pressure. The velocity of the AC blower and the percentage of exhaust openings were varied so that suitable air pressure was obtained. Based on the analysis of the simulation results, it was known that the design of the car cabin that had been done could produce positive air pressure. This positive air pressure was obtained when the blower speed was low and the exhaust opening was 100%. The value of air pressure under these conditions was 101019 Pa or +19 Pa from the ambient air that have 101000 Pa in Yogyakarta.

Prototype of Automated Vehicle Window Using the Detection of Raindrop Sensor

This project presents prototype of vehicle window using the detection of raindrop sensor in order to reduce heat trapped in the prototype. This project will investigate the effectiveness of heat dissipation at different opening gap of power window. The climate seasons are almost the same throughout all year. Temperature are uniformly high throughout the year, it can range up to 33°C and drop as low as 23°C. Meanwhile, the mean annual rainfall of Malaysia is approximately 2540mm. Since high number of houses in Malaysia does not have garage to park their vehicle inside, the temperature of the car cabin can reach a high temperature when the weather is hot. The rise in temperature in the vehicle cabin is caused by the ultraviolet ray from the sun that passes through the window and windscreen of the vehicle. The amount of ultraviolet ray passing through can be reduced by tinting the window but it is not effective. The propose mechanism for the prototype of vehicle window to reduce the interior cabin temperature. Finally, evaluate the effectiveness of the prototype vehicle window mechanism in reducing the interior cabin temperature. Studies will be conducted to investigate the factors of increasing temperature inside the car cabin. A prototype of vehicle window will be built to propose the mechanism. To evaluate the effectiveness of the prototype vehicle window mechanism in reducing the interior temperature is done by conducting 2 experiments. By doing this project, the prototype has proven that the implementation of automated power window to dissipate heat is effective with the use of raindrop sensor.

TYPOLOGY OF CAR GLASS FILM TOWARDS CLIMATE IN ANTICIPATION TO GLOBAL WARMING

Climate change has a significant impact on the socio-economic and development of Indonesia. Transportation in this study is related to cars where cars require a lot of fuel consumption. Window Film is able to reject Infrared from sunlight which ensures that the car cabin will feel cooler can help overcome climate change. This study explains how the right type and and the percentage of window are used in the tropics to deal with global climate change. The purpose of this study was to analyze the parameters of temperature, wind speed, lighting, and noise originating from the outside of the car on the ability of each type of car window film to reduce heat. The research method used is the method of collecting data by taking data on the characteristics of temperature, lighting, wind speed and noise inside the car and outside the car which affect the window film. The results of scoring the noise quality standard using the application from SPSS using Crosstab, the quality standard is at a Moderate level between 56-65 db(A), the quality standard lighting level is at a Moderate level between 500-999 Lux, the wind speed to humans is at a very high level. The average score between Effective Temperature and Minimum Humidityis 24.46°C with 63% Humidity. Typology of 40% window film with a combination of glasswall dampers is able to reduce the value of climate parameters from outside the car.

TYPOLOGY OF CAR GLASS FILM TOWARDS CLIMATE IN ANTICIPATION TO GLOBAL WARMING

Climate change has a significant impact on the socio-economic and development of Indonesia. Transportation in this study is related to cars where cars require a lot of fuel consumption. Window Film is able to reject Infrared from sunlight which ensures that the car cabin will feel cooler can help overcome climate change. This study explains how the right type and and the percentage of window are used in the tropics to deal with global climate change. The purpose of this study was to analyze the parameters of temperature, wind speed, lighting, and noise originating from the outside of the car on the ability of each type of car window film to reduce heat. The research method used is the method of collecting data by taking data on the characteristics of temperature, lighting, wind speed and noise inside the car and outside the car which affect the window film. The results of scoring the noise quality standard using the application from SPSS using Crosstab, the quality standard is at a Moderate level between 56-65 db(A), the quality standard lighting level is at a Moderate level between 500-999 Lux, the wind speed to humans is at a very high level. The average score between Effective Temperature and Minimum Humidityis 24.46°C with 63% Humidity. Typology of 40% window film with a combination of glasswall dampers is able to reduce the value of climate parameters from outside the car.

Revisiting the dynamics of car cabin environment and driver comfort

Revisiting the dynamics of the car cabin environment and its impact on driver comfort is essential, as these concepts have not been explored in recent years. Older methods of assessing driver comfort and cabin environments require elaborate experimental settings and prolonged engagement of study participants, making repeatability difficult. Therefore, this study develops a model for study models the car cabin environment based on temperature, humidity, and CO2 levels using a thermal imager, an air quality device, and open-source temperature and humidity data. This study also determines whether the impact of the cabin thermal environment on driver comfort (skin dryness, eye fatigue, body fatigue, and body heat) can be quantified based on driver perceptions. The study results showed that body fatigue decreased from 4.2 to 2.7 when the average relative humidity is reduced from 37.2% to 24.2%, and the temperature dropped from 41.8°C to 40.0°C. Notably, the impact of air temperature on the cabin thermal environment was 1.8 times stronger than that of the car skin temperature. Cabin temperature was found to be a better predictor of driver (dis)comfort than cabin humidity and CO2 levels. A 10 min exposure to summer heat in the UAE was found to have a significant effect on drivers’ perceptions of body fatigue, body heat, and eye fatigue. Overall, these findings have implications for car cabin ergonomics and future thermal comfort research.

Experimental research on the humidity in a passenger car cabin equipped with an air cooling system - development of a simplified model

The paper presents the results of research on humidity in a passenger car cabin equipped with an air cooling system in the summer season in a temperate climate in north-eastern Poland. The choice of the summer season was due to the fact that in temperate climates, the option of air cooling is most often used in the summer period on hot days. Based on the literature, the air quality in the passenger car cabin was assessed in terms of temperature and humidity. The test results were also compared with the results of previous study in which driving a car in summer with air supply without cooling options was investigated. The operation of the cooling system in the car caused a significant decrease in the relative humidity of the air in the car cabin in relation to the relative humidity of the outside air. The average value of relative humidity in the passenger car cabin amounted to between 27.5 % and 49.3 %. The temperature inside the passenger car cabin ranged from 19.7 °C to 33.5 °C and was lower compared to the temperature in the passenger car cabin with the cooling system turned off. The paper presents a model of moisture content in a passenger car cabin as a function of time, number of people, cabin volume and the number of air changes. The presented model based on the moisture balance in the car cabin can be used in algorithms for automatic regulation of car ventilation.

Analyzed of Convection Heat Transfer in Cabin Car Equipped With Air Conditioner (AC) Using A Simple Method Assisted by Microsoft Excel

Visualization of heat flow often uses complex and challenging programs such as Matlab and Ansys Fluent with expensive licenses, and the operation is also difficult. This study aims to demonstrate the phenomenon of convection heat transfer in a simple way. The phenomenon of convection is fairly difficult, and the heat transfer process can cause misconceptions in students. An appropriate and easy-to-use method is needed in preparing for classroom learning. This study was conducted to review the air condition in the car cabin, which is influenced by airflow from the air conditioner, and visualize it. This visualization can be used to explain the phenomenon of heat transfer by convection to students, especially while cooling the car's air conditioner. This research was conducted using a car model with three rows of seats where the air conditioner is only on the front cabin dashboard. On the dashboard, the AC flows are located on the left, right, and center. The calculation is carried out by applying the Black Principle, where other particles around it influence the particle temperature. Microsoft Excel is used to perform mathematical operations and visualize the results in graphs. It successfully delivers a 2D image showing heat distribution in the car cabin space. Visualization of this convection phenomenon can provide an overview of the convection flow phenomenon. So, this method is very easy to operate and apply by teachers in preparing lessons on the phenomenon of temperature convection.

Interaction between two car models with application to pollutant dispersion

Nowadays, air quality monitoring is a major concern. Among pollutants, exhaust UltraFine Particles (UFP) have a harmful effect on health due to their small size and to their ability to penetrate the bloodstream, the respiratory system, the brain as well as the placental barrier. Out of the industrial emissions, road traffic is a major source of air pollution. UFP emitted from the cars can infiltrate the car cabin through leakages and ventilation system leading to poor air quality in the passenger compartment. Improving the knowledge regarding the dispersion of exhaust UFP in the wake of a car considering road traffic is then mandatory. In this paper, the dispersion of UFP is studied in the wake of a leading vehicle (LV) followed by a second one. Two rear slant angles (φ) for LV and 6 inter-vehicle distances are considered. Velocities and UFP concentrations are collected in a wind tunnel. The influence of the rear slant angle of the leading vehicle is discussed on both wake dynamics and concentration fields. The results indicate that a critical inter-vehicle distance can be identified above which the recirculation region remains unchanged. Considering the concentration fields, for a leading vehicle with φ=0°, the large recirculation region tends to entrap the particles and to homogenize the particle mixing. For φ=25°, the attachment of the flow in the rear slant angle has a strong impact on the particle dispersion. It leads to a small recirculation region, which entraps particles leading to a non-homogeneous mixing. The Particle Concentration fields in Number (PNC) reveal high levels in the exhaust tailpipe plane that can contribute to lower PNC levels in the car cabin. Comparisons with previous studies are discussed and possible recommendations are suggested.

Development and Performance Evaluation of Polytetrafluoroethylene-Membrane-Based Automotive Cabin Air Filter.

A high-efficiency, long-life cabin filter unit is required for the effective purification of the air inside a vehicle. However, conventional cabin air filters that utilize electrostatic effects are less efficient and less effective owing to environmental factors. Polytetrafluoroethylene (PTFE) membranes exhibit a high porosity and surface-to-surface dust-removal performance, and maintain a stable pressure drop, indicating their good potential as filter materials. Therefore, in this study, the use of PTFE membranes for the fabrication of automobile filters and the filtration performance of the filters were examined. To this end, first, the properties of PTFE membranes mainly used in HEPA air conditioning filters and those of membranes used as vehicle cabin filters were compared. Next, the thickness, weight, stiffness, pore size, and filtration performance characteristics of filter media fabricated by blending melt-blown (MB) nonwoven, PTFE membranes, and supporting nonwoven into a total filtration layer were compared and analyzed. Lastly, the environmental change durability performance of the automobile cabin filter based on PTFE membrane and the results of the test after the installation of the filter in a vehicle were demonstrated.

A study on coherence between virtual signal and physical signals in remote acoustic sensing.

Remote acoustic sensing can be used to estimate the error signals in human ears without placing any physical microphones there. In this paper, the coherence between the signals picked up by physical microphones over a sphere surface and the signal obtained at the sphere center is investigated. Based on the multiple channel coherence formulas in the time domain and frequency domain, the relationship between the coherence and the placement of physical microphones is analyzed by numerical simulations first, then the experimental results obtained in a reverberation chamber and a car cabin are presented to verify the simulation results. Finally, a placement of physical microphones for active control of road noise in car cabins is discussed. Both the numerical and experimental results show that an upper limit frequency exists for accurate sound pressure estimation at the center of a sphere with the sound pressure on the sphere surface. For a sufficiently complex sound field such as that in a reverberation room or in a car, half the wavelength of the upper limit frequency is about the average distance among the physical microphones.

The Effect of Al_2 O_3 Addition on Solidification Process of Phase Change Material: A Case Study on Heating of Automobile Cabin in Cold Climate Conditions

In this paper, an experimental investigation is revealed on the solidification process of the latent heat thermal energy storage (LHTES) system, in which the heat energy emitted into the atmosphere with the exhaust gases of ICE vehicles is stored by phase change material (PCM) enhanced with nanoparticles (Al2O3). In the study using RT55 paraffin wax as the PCM, the interior heating process of a typical sedan automobile in cold climate conditions is used as the heat release medium for the LHTES system. Experimental studies carried out in real climatic conditions were repeated for pure paraffin (RT55) and five dif-ferent Al2O3 fractions (5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%, and 25 wt.%). Ex-periments are performed in an optical PCM container and are completed after 1200 seconds (20 minutes). The heat energy stored in the PCM container is discharged to the automobile cabin via the closed-circuit liquid circulation system by the heating radiator system in the automobile cabin. The findings showed that the solidification process is improved considerably up to 10 wt.% Al2O3 fractions compared with pure paraffin RT55, and the temperature in the cabin could be increased by approximately 29%. In addition, the Al2O3 frac-tion increased by more than 10 wt.%, which has a negative effect on the im-provement in the solidification process, but higher solidification ability and in-cabinet temperature were obtained with all Al2O3 fractions compared to pure RT55.

Nanoscale physical and chemical properties of individual airborne magnetic particles from vehicle emissions

Diesel and petrol powered vehicles are contributors to the magnetic fraction of atmospheric particles in the urban atmosphere. For an assessment of the health effects of vehicle-emitted magnetic particles, the mineralogical characters of particles present in engine exhaust vs. those produced by braking need to be understood. We collected magnetically separated individual particles directly from both brake wear and engine exhaust, from the air inside a car cabin while driving on a motorway, and from the ambient urban atmosphere. The morphologies, sizes, chemical compositions and spatial associations of magnetic particles with other constituents of vehicle emissions were characterized using scanning and transmission electron microscopy techniques. Magnetic separates typically contained particles that were aggregates of a large number of nanocrystals. Particles from engine exhaust, car cabin and urban air were similar, with diameters ∼1–4 μm, consisting predominantly of ∼10 nm-sized, randomly oriented crystals of magnetite and minor hematite. In contrast, brake debris particles were larger (∼1–10 μm in diameter) and contained mostly ∼7 nm-sized hematite, in addition to metallic iron and minor goethite. Particles in all samples comprised carbonaceous constituents besides iron oxides. In the exhaust and ambient particles carbon was present in both amorphous and semi-ordered forms, encompassing the nanocrystals, suggesting a high-temperature formation. In contrast, only amorphous carbon was found in brake wear. Besides the main components (Fe, O, C) several additional elements, including Mg, Al, Si, P, S, Cl, Sn, Ca, Mn, Zn, Cu, Pb and Zr occurred in the particles, with some minor differences between the distinct types of samples. Whereas the overall characteristics of magnetic particles in exhaust emissions were similar to those of ambient particles, the brake emissions produced slightly different particle types, particularly in terms of size and mineralogy. Thus, based on the qualitative assessment of particle properties in direct emissions and ambient air, a significant portion of magnetic particles in urban air appears to originate from vehicle emissions. Although the aggregate particles have sizes in the μm range, they still may represent a potential health risk on inhalation. Synopsis: This article discusses the nanoscale properties of magnetic particles from vehicle emissions, for a better understanding of their sources and health effects. • The magnetic fraction of vehicle-derived airborne particulate matter can be collected using a simple device. • Exhaust emissions may constitute a substantial source of magnetic particles in urban environments. • Magnetic fraction of brake wear predominantly originates from the corrosion of the brake disc. • The primary magnetic agglomerates are small enough to reach the lungs upon inhalation.

The variation of temperature in parked car's cabin in the summer

This study aimed to investigate the inside temperature variation of two cars with different colours (black vs. white) in the conditions: doors fully closed vs. doors partially opened; sunny parking area vs. shaded parking area. Several temperature devices - Maxim Integrated DS1921 Hygrochron iButton were used to measure continuously and simultaneously both outdoor and indoor temperatures of the black and white cars. The results of this study showed that the temperature of a black car’s cabin was higher than that of white car’s cabin because the black colour absorbs sunlight more than the white colour. The results reported that the increase in temperature of the car’s cabin under the condition of closed doors and unshaded parking area was higher than that in other conditions. After 30 min (from 3:10 PM to 3:40 PM) of exposing to sunlight, the highest temperature of the black car’s cabin was 40.5 °C, meanwhile that of the white car’s cabin was 37.5 °C. Therefore, during the time of stationary, the automobile should be parked in shaded parking area in the summer.

Effect of Velocity and Type of Cooling Fluid on Peltier Heat Transfer for Car Cabin Cooling Applications

This research used the Peltier element as a car cabin cooler. This research aimed to compare the results of the lowest temperature produced by the Peltier element on the hot side. The design of this monitoring tool consists of LM35 as a temperature sensor and an electric velocity sensor to measure the velocity of the cooling fluid. Arduino Uno Microcontroller to control the system before being displayed to the LCD. The type of research used in this research is experimental research. In this study, variations in fluid flow velocity and type of cooling fluid were carried out. The fluid used is a mixture of water and water coolant with a ratio of 50%:50%. The results showed that the circulation of fluid cooling influences the temperature on the hot side of the Peltier. In cooling using water fluid, when the water pump rotates 4.5 liters/second, the temperature on the hot side of the Peltier is 36ᵒC. At the time of rotation of 13 liters/second, the temperature on the hot side of the Peltier is 32ᵒC. The difference between cooling using water fluid, water coolant, or a mixture of water and water coolant greatly affects the temperature produced on the cold side of the Peltier. In cooling using water, the lowest temperature produced reaches 8ᵒC. When the cooling using a fluid coolant, the lowest temperature reaches 6ᵒC. While cooling using a mixture of water and coolant, the lowest temperature reaches 3ᵒC. So it can be concluded that cooling using a mixture of water and water coolant is very effective compared to other fluid coolers.

A new method for location of the main contribution modes by the decomposed sound pressure

The control of loud structure-borne noise inside car cabins is commonly by analyses such as panel acoustic contribution analysis, sensitivity analysis, and optimization analysis, to find suitable and practical structural modifications. However, these analyses are usually repeated dozens of times before accessing effective structural modifications, which requires more computation and time. This paper presents a new way to decompose sound pressure and quickly locate structural and acoustic modes of the main contribution for efficient access of feasible structural modifications. The decomposition process of the sound pressure inside structure-acoustic coupled systems was summarized by analyzing specific mathematical formulas. The details for locating the structural and acoustic modes of the main contribution by the decomposed sound pressure were investigated, taking a typical structure-acoustic coupled system of a rigid box with one flexible wall at bottom as an example. To evaluate the correctness of the main contribution modes, modifications were suggested in the structural modes of the main contribution, based on the mechanics of structure-acoustic coupling. The results indicated that the interior sound pressures of structure-acoustic coupled systems are decomposed into matrices by certain mathematical formulas. The main contribution modes are located by analyzing larger data in the decomposition matrices. The modifications in the structural modes of the main contribution reduce the corresponding sound pressure, which shows the correctness of the main contribution modes found. Furthermore, one way for quick suggestion of effective structural modifications was proposed, which offers a potential option for the reduction of structure-borne noise inside car cabins.

The influence of different orientations and ventilation cases on temperature distribution of the car cabin in the hot soak

Thermal discomfort, fuel wastage, health risks, and the death threat of passengers/infants due to the hot soak of car cabin is a hot spot topic all the time. Therefore, the transient analysis method is used to study the distribution of the heat soak temperature in the passenger compartment under different orientation. Besides the research analyzed the effects of four ventilation cases on the driver and rear infant. The results show that both of the driver and infant are subjected to the lowest heat load while the vehicle parked outdoors is facing east at 14:00 and the air temperature around the driver is about 52 °C. The roof ventilation is a effective energy conservation ventilation way for both of driver and infant, as there is the most heat removal efficiency(0.471) and the best cooling effect. The head temperature of driver and infant in roof ventilation is at least 7 °C and 3 °C lower than the other three cases. In addition, the seats ventilation is a better heating way for driver than other ventilation cases, because the air temperature is more even and can be heated to 26.5–29.2 °C for the driver.