Vehicle Passenger Compartment Research Articles

Relationships between Electroencephalogram and Thermal Perception of Passenger in Winter Vehicle Compartments

The development of electric vehicles (EVs) has prompted a critical examination of the trade-off between range and human thermal comfort. Therefore, an accurate, real-time assessment of human thermal perception inside vehicles is important. This study investigates an electroencephalogram- (EEG-) based method for evaluating human thermal comfort in the vehicle passenger compartment. Under transient winter heating conditions, the study experimentally investigates the correlation between objective physiological parameters (skin temperature and electroencephalogram) and subjective human thermal perception. The results reveal distinct patterns in EEG signals corresponding to changes in thermal perception. Specifically, the δ rhythm exhibits a U-shape variation with increasing thermal perception, while the θ, α, β, and γ rhythms display an inverted U-shape variation. Differences in each frequency band across thermal comfort states in humans are greater than differences in the frequency band across thermal sensation states. Furthermore, the relative power of the θ rhythm emerges as the most effective in discerning the thermal perception state of the human body. The EEG signal characteristics of the T7 and T8 channels align more closely with human thermal sensation, whereas the AF4 channel excels at discriminating the state of human thermal comfort. The insights gained from this study serve as a foundation for evaluating human thermal perception in vehicles, enhancing human-vehicle interaction, and addressing challenges related to human thermal comfort and vehicle range.

Heat Characteristics and Emission Effect of a Fuel-operated Auxiliary Air Heater Fed with Fuel E10, E30 and E100

In order to increase the comfort of vehicle passengers in specific vehicle categories, the heating of the passenger compartment is not provided by the heat from the engine driving the vehicle but by an additional heating device. The study examines the effect of auxiliary heaters that use liquid fuels to heat the passenger compartment of vehicles. The device was operated during the test with two different mixtures containing bioethanol (E30, E100) and the original motor gasoline (E10). It aimed to understand the effects of different fuels, particularly heating performance, operating time and emissions. Based on the results, as the ethanol content increases, the temperature of the device’s flame and heating air decreases. The experiments showed that in the case of E100 bioethanol, the average temperature measured in stable operating conditions was significantly lower than in the case of E10 motor gasoline. That suggests that an increase in the ethanol content reduces the heating performance. Another significant result of the study was that in the case of mixtures containing ethanol, a longer operating time is required to achieve the same amount of heat, which leads to additional fuel consumption. In addition, when using E100 bioethanol, the amount of harmful gases that are emitted increases significantly during the longer operating time. This observation can be important for evaluating the environmental impact and efficiency of vehicles.

Research on the influence of traffic conditions on noise level in the passenger compartment of motor vehicles

The research investigates the noise levels measured in the passenger compartments of several automobiles. These vehicles are powered by various engines, travel on various highways, and function at differing speeds and acceleration. The results are visually processed using specialist software. The study investigates the effects of three major sources of automotive noise: engine operation, tire-road contact, and friction between the car body and the air. The immis noise in the passenger compartment is reported to be mostly impacted by the engine’s operational characteristics (load and speed) at lower speeds. In contrast, as travel speed increases, the noise produced by tire-road contact becomes more substantial, and at greater speeds, the noise produced by the interaction between the car body and the air becomes more significant. As a result, the engine type, tire and road characteristics, vehicle speed, and passenger compartment acoustic insulation are all important elements in influencing noise emission in the passenger compartment.

Contribution of Side Surfaces to the Effectiveness of Automotive Sound-Absorbing Materials

When developing noise-reducing structures for passenger, engine and luggage compartments of motor vehicles, an objective assessment of their sound-absorbing properties is important. The method of measuring the reverberation time of a diffuse sound has found the widest distribution. This method provides sufficient reliability and repeatability of measurement results. However, often the values of reverberation sound absorption coefficient are exceeded relative to the actual values. The article investigates the influence of side surfaces of sound-absorbing materials on equivalent sound absorption. The frequency range of effective absorption by side surfaces is indicated. An updated formula for approximate calculations is given.

Development of a simulation model of the heating process in the passenger cabin of a vehicle under low temperature conditions

Introduction. A distinctive feature of working conditions in the Arctic territories is the long period of exposure to low temperatures. Passenger transportation by road is becoming one of the key aspects of ensuring the continuity of the production process. The task of delivering workers to the place of work, moving them between work zones during a work shift is solved by using wheeled vehicles of various categories. One of the most widespread types of wheeled vehicles used to transport workers is the M3 category wheeled vehicles with a capacity of no more than 22 passengers. Ensuring the thermal comfort of vehicle passengers seems to be relevant, since ensuring biophysical compatibility minimizes the risks of cold injury by workers and maintains a high level of performance.Materials and methods. The results of the analysis of the Russian and foreign studies in the direction of ensuring thermal comfort and ensuring biophysical compatibility in confined spaces are presented. The results of computer modelling of the dynamics of microclimate parameters in the passenger cabin of a wheeled vehicle of M3 category with a capacity of no more than 22 passengers are presented.Results. The paper presents the results of theoretical studies, microclimate parameters in the passenger compartment of vehicles, taking into account the breathing of passengers and changes in the gas composition of exhaled air. Theoretical studies of the operation of the heating system of the passenger compartment were carried out, taking into account the refined breathing model of passengers. Distributions of microclimate parameters in the section of the passengercompartment were obtained when using a heating system with one heater; the impact of passengers’ breathing on the parameters of the microclimate in the passenger compartment was assessed.Discussion and conclusion. Based on the numerical solution of the system of heat transfer equations, directions for further research and recommendations are formulated to ensure thermal comfort in the passenger compartment of a wheeled vehicle at low temperatures. The materials of the work may be of interest to specialists involved in the design and ergonomics of wheeled vehicles, labor protection.

Computational fluid dynamics simulation and performance optimization of an electrical vehicle Air-conditioning system

In vehicles, air conditioning tends to offer efficient thermal conditioning and air circulation inside cabin for passenger comfort from different climate variation. The working performance of air conditioning system in vehicles is an essential factor for thermal comfort and driving safety of the passenger compartment of vehicles. Therefore, it is of great significance to construct a numerical simulation model for theoretical analysis and performance evaluation of vehicle air conditioning system. In current research, the air conditioning system of an electric vehicle is taken as the research subject. Internal flow field characteristics of air conditioning system is investigated by Computational Fluid Dynamics (CFD). Results show that the air flow in air-conditioning system is relatively smooth, and the velocity distribution in the front windshield A area and the driver's field of vision of the left and right windows is not ideal when the defrosting-demisting mode is on; the velocity and air quantity distribution of the two outlets in the middle air duct are not uniform under blowing mode. In view of the uneven distribution of velocity and air quantity, the corresponding optimization scheme is proposed. After optimization, the cell relative velocity of the front windshield is significantly improved, and velocity distribution of the side window glass is slightly increased and the defrosting-demisting performance meets the vehicle defrosting requirements of national standard; after optimization, the air quantity distribution of the air ducts at blowing mode is more uniform, which is conducive to the comfort of the passenger compartment.

Research on mechanism and evolution features of frequency split phenomenon of tire acoustic cavity resonance

The acoustic cavity resonance inside the tire–wheel assembly is known to contribute to audible noise in the passenger compartment of vehicles. To obtain control methods of tire acoustic cavity resonance, its characteristics and producing mechanism need to be clarified first. In this article, the finite element model of a tire coupled with acoustic medium in the tire cavity is constructed. The Euler method is introduced to study the modal characteristics of tire cavity under the influence of tire inflation pressure, load, and tire rotation velocity. Frequency splitting phenomena under four separate conditions (stationary tire without load, stationary tire with load, rotating tire without load, and rotating tire with load) are simulated and analyzed. The slope change of the resonance frequency as a function of rotation speed is found to be close to the reciprocal of tire radius which can be explained by a model of wave propagation in a ring-shaped channel with moving media inside the ring. The obtained function of the slope change can help determine the frequency variation range under different vehicle velocity, structure load, and tire inflation pressure, which can then help to control the cavity resonance energy and provide a more comfortable driving experience.

Test Methods and Equipment for Assessment of Passenger Compartment Environmental Parameters of Modern and Advanced Driverless Vehicles

At the moment, no due attention is paid to the problem of ensuring environmental safety of passenger compartments of modern and advanced vehicles, including the driverless ones. The objective of this research is to analyze solutions to this social problem by developing, at this stage, of a new test method and equipment for assessment of parameters of passenger compartments of modern and advanced driverless vehicles.

Experimental analysis of sound field in the tire cavity arising from the acoustic cavity resonance

The acoustic cavity resonance noise inside the tire-wheel assembly is known to contribute to audible noise in the passenger compartment of vehicles, but it is difficult to attenuate the effect of tire cavity resonance noise. The purpose of this paper is to experiment and analyze the sound field in the tire cavity of a revolving tire through a customized sound pressure sensor fixed on the inner surface of the tire, and to obtain the distribution and frequency characteristics of sound field. Furthermore, the paper concerns the effects of the inflation pressure, the running velocity, and the load on the sound pressure distributions and its frequency characteristics, and the influence of these parameters are analyzed. The research is helpful to understand and attenuate the tire acoustic cavity resonance.

Noise contribution analysis of a vehicle passenger compartment

In this study, integration of acoustic source quantification (ASQ) and SEA methodologies is aimed to model the interior noise level inside the passenger compartment. The ASQ direct method, briefly explained in theory section, has been used to perform panel acoustic contribution analysis (PACA), in order to investigate regions with panels that contribute primarily to the interior noise level and to determine opportunities for refining the interior noise levels within vehicles. To determine the airborne contributions of engines, the ASQ indirect method, briefly explained in theory section, has been applied. By creating a contribution model using MATLAB (PACA and engine ASQ), the interior noise level of the vehicle has been calculated and correlated with the test results. By performing further analysis on the interior noise contribution model and focusing on the panel contributions, the regions with the most contributing panels have been determined and interior noise refining actions have been applied. By applying interventions, which are the refining outputs of the panel acoustic contribution analysis, an improvement in the A-weighted level of up to 3 dB for a few engine speed ranges has been obtained for the overall noise level of the vehicle. In addition to the panel contribution analysis, which is the primary focus of this study, thickness optimization of the inner dash isolator has been performed for a correlated SEA model, which confirms that no performance loss occurred in the acoustic transfer functions from the engine to the passenger compartment. The physical prototype of the optimized inner dash isolator has been assembled in the vehicle during the panel contribution analysis validation tests.

リアシートと車室内音場の連成を考慮した伝達特性の検討

Excellent quietness of passenger compartment of vehicles is demanded for vehicles with low interior noise such as electric and hybrid vehicles. Therefore, the investigation of acoustic transfer function of passenger compartment of vehicles is required to increase these quietness. The coupling effects between passenger compartment and trunk of vehicles affect acoustic response of the passenger compartment at the low frequency in sedan type vehicle. Air leakages and vibration of poroelastic materials of a rear seat between the cavity and the trunk are also known to affect acoustic response of the cavity at the low frequency. However, most studies of the coupling effects between the cavity and the trunk do not consider the influence of poroelastic materials of a rear seat between the cavity and the trunk. In this study, we investigated acoustic transfer function of the cavity of vehicles that is affected by poroelastic materials of a rear seat. The experimental results showed that poroelastic materials reduce the acoustic response of the cavity at low frequencies and change the coupled natural frequencies. The calculated results showed that poroelastic materials of rear seat can be modeled by Biot's theory. The calculated results also showed that poroelastic materials of a rear seat can be modeled by elastic materials if there is no air permeability. Then, theoretical study is made using a one-dimentional mathmatical model. The features of coupled natural frewuencies could be explained by this model.

Characteristic of the fractures of the cervical, thoracic and lumbar vertebrae in the victims of a traffic accident found in the passenger compartment of a modern motor vehicle

The objective of the present work was to study peculiar features of the injuries to three spinal regions in the victims of a head-on car collision found in the passenger compartments of modern motor vehicles equipped with seat belts and other safety means. It was shown that most frequent fatal injuries to the driver include the fractures of the cervical, thoracic, and lumbar vertebrae. These injuries are much less frequent in the passengers occupying the front and the right back seats. The multilayer and multiple character of the fractures in different parts of the spinal column in the car drivers is attributable to more pronounced spine flexion and extension associated with injuries of this kind. The fractures of the lower cervical vertebrae in the front seat passengers occur more frequently than injuries of a different type whereas the passengers of the back seats most frequently experience fractures of the upper cervical vertebrae. The passengers of the left back seat less frequently suffer from injuries to the thoracic spine than from the fractures of the cervical and lumbar vertebrae. The passengers of the central back seat most frequently experience fractures of the thoracic part of the vertebral column and the passengers occupying the right back seat fractures of the lumbar vertebrae.

The Third-Order Viscoelastic Acoustic Model Enables an Ice-Detection System for a Smart Deicing of Wind-Turbine Blade Shells

The present work is based on the third-order partial differential equation (PDE) of acoustics of viscoelastic solids for the quasi-equilibrium (QE) component of the average normal stress. This PDE includes the stress-relaxation time (SRT) for the material and is applicable at any value of the SRT. The notion of a smart deicing system (SDS) for blade shells (BSs) of a wind turbine is specified. The work considers the stress in a BS as the one caused by the operational load on the BS. The work develops key design issues of a prospective ice-detection system (IDS) able to supply an array of the heating elements of an SDS with the element-individual spatiotemporal data and procedures for identification of the material parameters of atmospheric-ice (AI) layer accreted on the outer surfaces of the BSs. Both the SDS and IDS flexibly allow for complex, curvilinear and space-time-varying shapes of BSs. The proposed IDS presumes monitoring of the QE components of the normal stresses in BSs. The IDS is supposed to include an array of pressure-sensing resistors, also known as force-sensing resistors (FSRs), and communication hardware, as well as the parameter-identification software package (PISP), which provides the identification on the basis of the aforementioned PDE and the data measured by the FSRs. The IDS does not have hardware components located outside the outer surfaces of, or implanted in, BSs. The FSR array and communication hardware are reliable, and both cost- and energy-efficient. The present work extends methods of structural-health/operational-load monitoring (SH/OL-M) with measurements of the operational-load-caused stress in closed solid shells and, if the prospective PISP is used, endows the methods with identification of material parameters of the shells. The identification algorithms that can underlie the PISP are computationally efficient and suitable for implementation in the real-time mode. The identification model and algorithms can deal with not only the single-layer systems such as the BS layer without the AI layer or two-layer systems but also multi-layer systems. The outcomes can be applied to not only BSs of wind turbines but also non-QE closed single- or multi-layer deformable solid shells of various engineering systems (e.g., the shells of driver or passenger compartments of ships, cars, busses, airplanes, and other vehicles). The proposed monitoring of the normal-stress QE component in the mentioned shells extends the methods of SH/OL-M. The topic for the nearest research is a better adjustment of the settings for the FSR-based measurement of the mentioned components and a calibration of the parameter-identification model and algorithms, as well as the resulting improvement of the PISP.

Research on Content of Particulates in Passenger Compartments of Motor Vehicles in Operating Conditions

The article delivers the research results on content of particulates in passenger compartments in the course of driving in urban settings and results of assessment of air cleaning with serial and specially designed cabin air filters. It has been established, that particulates air pollution in passenger compartments in operating conditions is high and dangerous. There is no ecological standards on efficiency of air cleaning in passenger compartments. Thus, the vast majority of cabin air filters are ineffective in dealing with particulates that are less than 1-2 microns, which are the most dangerous for humans. It has been experimentally proven that efficient cabin air cleaning for limiting the content of the particulates that are less than 1-2 microns is technically feasible by means of particular air cleaning ecosystems, which allows justifying development of new ecological standards for “environmentally friendly vehicles”.

Analyzing panel acoustic contributions toward the sound field inside the passenger compartment of a full-size automobile

The Helmholtz equation least squares (HELS)-based nearfield acoustical holography (NAH) is utilized to analyze panel acoustic contributions toward the acoustic field inside the interior region of an automobile. Specifically, the acoustic power flows from individual panels are reconstructed, and relative contributions to sound pressure level and spectrum at any point of interest are calculated. Results demonstrate that by correlating the acoustic power flows from individual panels to the field acoustic pressure, one can correctly locate the panel allowing the most acoustic energy transmission into the vehicle interior. The panel on which the surface acoustic pressure amplitude is the highest should not be used as indicative of the panel responsible for the sound field in the vehicle passenger compartment. Another significant advantage of this HELS-based NAH is that measurements of the input data only need to be taken once by using a conformal array of microphones in the near field, and ranking of panel acoustic contributions to any field point can be readily performed. The transfer functions between individual panels of any vibrating structure to the acoustic pressure anywhere in space are calculated not measured, thus significantly reducing the time and effort involved in panel acoustic contributions analyses.

Performance evaluation of an R134a automotive heat pump system for various heat sources in comparison with baseline heating system

Engine waste heat is commonly used for comfort heating and defogging windows of the passenger compartment of motor vehicles. However, the amount of waste heat to be used for these purposes decreases continuously as a result of increasing engine efficiencies. These requirements can also be met by employing an automotive heat pump (AHP) system. This study presents performance characteristics of an experimental AHP system employing an R134a vapour compression refrigeration circuit and driven by a diesel engine. The AHP system is capable of providing a conditioned air stream by utilizing the heat absorbed from any of the three sources, namely ambient air, engine coolant and exhaust gas. The steady-state and transient performance of the AHP system for each heat source was evaluated by applying energy and exergy analysis to the system based on experimental data. Then, a performance comparison of the AHP system with the three heat sources and baseline heating system was made. It was determined that the AHP system using engine coolant provided the highest indoor coil outlet air temperature during the tests until the steady-state was achieved compared with the AHP system using other heat sources as well as the baseline heating system.

Numerical modeling and active noise control of impact road noise inside a vehicle compartment

Even though active noise control (ANC) technique has been widely investigated and proven its efficiency for low-frequency vehicle interior noise control, current applications are mainly for the steady noise process such as powertrain noise and uniform road noise. When impulsive road disturbances due to road bumps or potholes are present, they may hinder the performance of the ANC system. One of the reasons is that the prevalent ANC algorithm, namely the filtered- x least mean square (FxLMS) algorithm, has been developed assuming that the signals follow the normal distribution. The impact road noise due to a sudden impact may exhibit a non-Gaussian characteristic. Hence, the FxLMS algorithm may not be appropriate for controlling this type of impulsive noise. In this study, a robust ANC system configured with a modified FxLMS (MFxLMS) algorithm by incorporating thresholds on reference and error signal paths is proposed for impact road noise control. To aid in the control system design, the spectral-based substructuring technique is implemented to develop a coupled vehicle system model to simulate the impulsive interior acoustic response due to road unevenness. The vehicle passenger compartment is simplified as a 3-dimensional flexible-panel backed cavity model, which is coupled with the tire-wheel system modeled as a flexible ring element and rigid wheel through the suspension system represented by a spring-damper model. The tire-road interaction is modeled as a set of flexible elements with certain stiffness over a half-cosine wave road bump. Numerical simulation results show that the proposed ANC system can effectively deal with the interior impact road noise without instability issue that may occur in the existing FxLMS algorithm. In fact, results show that approximately 8 dB reductions are achieved at the driver's ear position.

ИССЛЕДОВАНИЕ И РАЗРАБОТКА ОЦЕНОЧНЫХ КРИТЕРИЕВ АКУСТИЧЕСКОГО КОМФОРТА АВТОТРАНСПОРТНЫХ СРЕДСТВ

Ensuring the set level of acoustic comfort in passenger compartments of motor vehicles (hereinafter – MV) and low levels of external noise represents the important direction in their design and improvement. One of the important tasks in this process is the development of the objective criteria that characterize the attainable level of acoustic comfort of the developed construction of a vehicle. Well-known methods and objective criteria for assessment of acoustic comfort are characterized by limited load and high-speed modes of operation, complexity of interpretation and ranging of the obtained results, and insufficient correlation with results of the subjective expert opinion. The paper analyzes results of experimental studies of internal noise of 70 models of motor vehicles (cars) of the domestic and foreign manufacturers executed in road and bench test conditions. Road acoustic tests were carried out on public roads, moving with intensive acceleration, stabilized speeds, and motion with the engine switched off. Bench acoustic tests were carried out on motionless samples of motor vehicles in the conditions of a full-scale whirl tube and a big semi-anechoic acoustic chamber. In the course of analysis of the obtained results the researcher assesses statistical distribution of the studied parameters; the nature of their change depending on the load and high-speed modes of operation; chronological tendencies. The studied samples of MV are ranged into four categories of acoustic comfort in each of the studied modes of acoustic tests. The model of formation of a complex index of MV acoustic comfort has been developed based on the parameters of noise levels, levels of sound pressure at frequencies of motor harmonicas, and articulation indexes. Contribution of each of the acoustic parameters measured on various modes of tests is defined by empirical coefficients of weight. Objective criteria of ranging the acoustic parameters in various load and high-speed modes of operation can be used in technical requirements to design of the new and modernization of the existing models of MV. The complex index of acoustic comfort is offered to be applied for determination of competitiveness level and perfection of MV design within the target group of analogs.

Identification of moan-noise generation mechanisms by an experimental method and verification of the mechanism by finite element analysis

‘Moan’ noise in a vehicle is known to cause discomfort and anxiety to passengers. This abnormal noise is generated by a stick–slip phenomenon between the brake pad and the disc during breaking. The exciting force from the brake system is transmitted to a coupled torsion beam axle module through the brake pad, the caliper and an extra bracket. In this study, moan noise is reproduced during the vehicle’s operating test, and the parts of the coupled torsion beam axle module generating moan noise are identified. Further, it is verified that the resonance of the coupled torsion beam axle module due to the exciting force of the brake system is the main cause of moan noise. Coherence analysis and transfer path analysis were conducted to identify how the vibrations from the coupled torsion beam axle module are related to moan noise in the passenger compartments of vehicles. In the coherence analysis, the vibration accelerations of the brake pad, the caliper, the spindle bracket, the trailing arm and the V-beam are set as the inputs, and the output is the noise at the driver’s ear level. In terms of the frequency response, the results from a modal analysis of the coupled torsion beam axle module under the vehicle’s test conditions agreed well with those from a finite element modal analysis in which the boundary conditions of the vehicle were taken into consideration. The dynamic characteristics of the response from the coupled torsion beam axle module were identified using the exciting-force transfer mechanism of the brake system. The locations producing a large strain were determined by calculating the modal strain energy, and an improvement scheme with design modification was proposed for moan noise reduction.

Adiabatic Flow Simulation in an Air-Conditioned Vehicle Passenger Compartment

Dispersion and flow of air in passenger compartments of vehicles are important to assure a comfortable environment for passengers, driver concentration and safe driving conditions. The article describes numerical adiabatic flow simulations for the „mute“, an electric car. Air streams in its passenger compartment were simulated; air velocities were compared while using different turbulence models. The turbulence models were selected upon being screened for best-suiting characteristics. The eddy-viscosity standard, RNG k-e and SST k-ω models were used. Near-wall approaches (standard wall functions, scalable wall functions and enhanced wall treatment) were checked against a test case from “European Research Community on Flow, Turbulence and Combustion to determine the best choice for „mute“ passenger compartment air velocity simulations. (Received in March 2013, accepted in September 2013. This paper was with the authors 3 months for 2 revisions.)