Search Results

Volvo Car Corporation has developed a Reference Architecture for PAG1 Infotainment Systems. A Reference Architecture is an architecture scoping over more than a single system, i.e. an architecture aimed for a family of systems. The Infotainment Reference Architecture has since 2001 been successfully applied for the PAG family which so far covers the infotainment systems of Volvo XC90, Volvo S40/V50, Jaguar XK, Aston Martin DB9 and the brand new Volvo S80. In 1999, the system design departments started up with the clear objective to develop a system solution aiming for the PAG infotainment system family. The work was carried out according to the established development process at Volvo Cars. A year later a discouraging design review was performed. The number of involved functions, the level of function interaction and the distribution of functionalities between ECUs resulted in a non-manageable system solution.

Squeak and rattle (S&R) are nonstationary annoying and unwanted noises in the car cabin that result in considerable warranty costs for car manufacturers. Introduction of cars with remarkably lower background noises and the recent emphasis on electrification and autonomous driving further stress the need for producing squeak- and rattle-free cars. Automotive manufacturers use several road disturbances for physical evaluation and verification of S&R. The excitation signals collected from these road profiles are also employed in subsystem shaker rigs and virtual simulations that are gradually replacing physical complete vehicle test and verification. Considering the need for a shorter lead time and the introduction of optimisation loops, it is necessary to have efficient and inclusive excitation load cases for robust S&R evaluation.

Targets for reducing emissions and improving energy efficiency present the automotive industry with many challenges. Passenger cars are by far the most common means of personal transport in the developed part of the world, and energy consumption related to personal transportation is predicted to increase significantly in the coming decades. Improved aerodynamic performance of passenger cars will be one of many important areas which will occupy engineers and researchers for the foreseeable future. The significance of wheels and wheel housings is well known today, but the relative importance of the different components has still not been fully investigated. A number of investigations highlighting the importance of proper ground simulation have been published, and recently a number of studies on improved aerodynamic design of the wheel have been presented as well. This study is an investigation of aerodynamic influences of different tires.

In the early days of the automotive industry, durability and reliability were hit or miss affairs, with end-users often being the first to know about any durability problems - and in many cases forming an essential part of the development process. More recently, automotive companies have developed proving ground and laboratory test procedures that aim to simulate typical or severe customer usage. These test procedures have been used to develop the products through a series of prototypes and to prove the durability of the product prior to release in the marketplace. Now, commercial pressures and legal requirements have led to increasing reliance on CAE methods, with fatigue life prediction having a central role in the durability engineering process.

Existing battery parameter model structures are evaluated by estimating model parameters on real driving data applying standard system identification methods. Models are then evaluated on the test data in terms of goodness of fit and RMSE in voltage predictions. This is different from previous battery model evaluations where a common approach is to train parameters using standardized tests, e.g. hybrid pulse-power capability (HPPC), with predetermined charge and discharge sequences. Equivalent linear circuit models of different complexity were tested and evaluated in order to identify parameter dependencies at different state of charge levels and temperatures. Models are then used to create voltage output given a current, state of charge and temperature. The average accuracy of modelling the DC bus voltage provides a model goodness of fit average higher than 90% for a single RC circuit model.

To give the customer an immediate impression of quality several of criteria must be fulfilled such as styling, paint finish and fitting of outer panels/closures. Therefore, higher demands on geometrical quality e.g. stability for both exterior and interior are needed. The structural part of the car body is the key element for success. Beside the visual impression, lack of noise and vibrations during driving can convince a potential buyer to become an actual customer. To achieve this, car manufacturers have to draw up an overall strategy in combination with proper working methods to be able to guarantee a stable geometrical output throughout the entire development process and during series production over the lifetime of the vehicle. On a simultaneous engineering basis, the OEM, the system/component- and the process suppliers (for the industrial system from press shop to final assembly) have to adopt a common measurement strategy.

Maintaining the current ratio between certified and the customer-observed fuel consumption even with future required levels poses a considerable challenge. Increasing the efficiency of the driveline enables certified fuel consumption down to a feasible level in the order of 80 g CO₂/km using fossil fuels. Mainly affecting off-cycle fuel consumption, energy amounts used to create good interior climate as well as energy-consuming options and features threaten to further increase. Progressing urbanization will lead to decreasing average vehicle speeds and driving distances. Highly efficient powertrains come with decreased amounts of waste energy traditionally used for interior climate conditioning, thus making necessary a change of auxiliary systems.

Automotive turbo compressors generate high frequency noise in the air intake system. This sound generation is of importance for the perceived sound quality of luxury cars and may need to be controlled by the use of silencers. The silencers usually contain resonators with slits, perforates and cavities. The purpose of the present work is to develop acoustic models for these resonators where relevant effects such as the effect of a realistic mean flow on losses and 3D effects are considered. An experimental campaign has been performed where the two-port matrices and transmission loss of sample resonators have been measured without flow and for two different mean flow speeds. Models for two resonators have been developed using 1D linear acoustic theory and a FEM code (COMSOL Multi-physics). For some resonators a separate linear 1D Matlab code has also been developed.

The objective of this paper is to investigate whether different appearance modes of the digital human models (DHM or manikins) affect the observers when judging a working posture. A case where the manikin is manually assembling a battery in the boot with help of a lifting device is used in the experiment. 16 different pictures were created and presented for the subjects. All pictures have the same background, but include a unique posture and manikin appearance combination. Four postures and four manikin appearances were used. The subjects were asked to rank the pictures after ergonomic assessment based on posture of the manikin. Subjects taking part in the study were either manufacturing engineering managers, simulation engineers or ergonomists. Results show that the different appearance modes affect the ergonomic judgment. A more realistic looking manikin is rated higher than the very same posture visualized with a less natural appearance.

Most OEMs are shifting their strategy and way of thinking regarding ECUs. This, in combination with the electrification of vehicles and the shift towards software-based companies (car as a device), implies one of the biggest paradigm changes in automotive history. On the other hand, despite the current struggles, remarkable advances have been made in electronic technology during the past few years. These developments have opened a door to very promising enabling technology, with exterior lighting as a main target market. These circumstances seem to have created a perfect storm leading to new strategies for electronic control and driving for (front and rear) exterior lighting. We, at our company, have investigated the enabling technology, challenges, and benefits of this emerging exterior lighting approach, that we call ‘ECU-Less’.

The transition towards battery electric vehicles (BEVs) has increased the focus of vehicle manufacturers on energy efficiency. Ensuring adequate airflow through the heat exchanger is necessary to climatize the vehicle, at the cost of an increase in the aerodynamic drag. With lower cooling airflow requirements in BEVs during driving, the front air intakes could be made smaller and thus be placed with greater freedom. This paper explores the effects on exterior aerodynamics caused by securing a constant cooling airflow through intakes at various positions across the front of the vehicle. High-fidelity simulations were performed on a variation of the open-source AeroSUV model that is more representative of a BEV configuration. To focus on the exterior aerodynamic changes, and under the assumption that the cooling requirements would remain the same for a given driving condition, a constant mass flow boundary condition was defined at the cooling airflow inlets and outlets.

Many automotive electronic systems must be developed using a safety process. A preliminary hazard analysis is a first and an important step in such a process. This experimental study evaluates two methods for hazard identification using an electrical steering column lock system. Both methods are found to be applicable for hazard identification in an automotive context. It is also concluded that the induction with the failure modes method is less time consuming and easier to use than the method based on induction with generic low level hazards. Further, two proposals are presented to improve efficiency and consistency, reuse of generic hazards by component profiles and a domain specific catalogue of vehicle phases.

With the increase in fuel prices and the increasingly strict environmental legislations regarding CO₂ emissions, reduction of the total energy consumption of our society becomes more important. Passenger vehicles are partly responsible for this consumption due to their strong presence in the daily life of most people. Therefore reducing the impact of cars on the environment can assist in decreasing the overall energy consumption. Even though several fields have an impact on a passenger car's performance, this paper will focus on the aerodynamic part and more specifically, the wake behind a vehicle. By definition a car is a bluff body on which the air resistance is for the most part driven by pressure drag. This is caused by the wake these bodies create. Therefore analyzing the wake characteristics behind a vehicle is crucial if one would like to reduce drag.

Car body structures and the joints between beam members have a great impact on global vehicle stiffness. With the method presented in this paper it is possible to experimentally assess the stiffness of joints by a robust and economic means. The stiffness of a beam can easily be found experimentally just by cutting it in two and using the cross-sections to calculate the polar moment of inertia. When it comes to a joint, there are no formulae or explicit expressions describing its behavior. Therefore, measurement of its mechanical behavior has to be made. The dynamic joint method presented here does not need levers or a costly, rigid set-up, but an economical free-free set-up and cast-on weights. Furthermore, the same method can be emulated by FEM when a digital model exists.

A finite-element (FE) based method for numerically predicting fatigue life of MAG-welded thin-sheet structures has been established and tested. The method uses nodal forces and moments calculated along the weld line, together with an analytical expression for the structural stress at the weld toe. The calculated stress is used together with an experimentally determined Wöhler, or S-N, curve. A “stiff” welded joint with structural stress dominated by membrane forces is found to have a steeper S-N curve than a “flexible” joint with structural stress dominated by bending moment. All test results were seen to lie close to one of two different S-N curves. The proportion of bending stress over total structural stress could be used for choosing the appropriate S-N curve.

Galvanic corrosion between die cast AZ91D and AM60B and different fastener systems has been evaluated by exposure on trucks and in accelerated laboratory tests. The exposure time on the trucks was 3 years, corresponding to a mileage of about 300000 km. Samples were retracted and evaluated after 1 and 2 years exposure. Similar samples were also exposed to the Volvo Indoor Corrosion Test and the General Motors GM9540P-cycle B test. The correlation between the field data and the laboratory tests was evaluated, as was the sharp difference in the performance of the fastener systems in the two accelerated laboratory tests.

Efforts towards ever more energy efficient passenger cars have become one of the largest challenges of the automotive industry. This involves numerous different fields of engineering, and every finished model is always a compromise between different requirements. Passenger car aerodynamics is no exception; the shape of the exterior is often dictated by styling, engine bay region by packaging issues etcetera. Wheel design is also a compromise between different requirements such as aerodynamic drag and brake cooling, but as the wheels and wheel housings are responsible for up to a quarter of the overall aerodynamic drag on a modern passenger car, it is not surprising that efforts are put towards improving the wheel aerodynamics.

To elucidate the processes controlling the auto-ignition timing and overall combustion duration in homogeneous charge compression ignition (HCCI) engines, the distribution of the auto-ignition sites, in both space and time, was studied. The auto-ignition locations were investigated using optical diagnosis of HCCI combustion, based on laser induced fluorescence (LIF) measurements of formaldehyde in an optical engine with fully variable valve actuation. This engine was operated in two different modes of HCCI. In the first, auto-ignition temperatures were reached by heating the inlet air, while in the second, residual mass from the previous combustion cycle was trapped using a negative valve overlap. The fuel was introduced directly into the combustion chamber in both approaches. To complement these experiments, 3-D numerical modeling of the gas exchange and compression stroke events was done for both HCCI-generating approaches.

Fuel consumption of vehicles has received increased attention in recent years; however one neglected area that can have a large effect on this is the energy usage for the interior climate. This study aims to investigate the energy usage for the interior climate for different conditions by measurements on a complete vehicle. Twelve different NEDC tests in different temperatures and thermal states of the vehicle were completed in a climatic wind tunnel. Furthermore one temperature sweep from 43° to −18°C was also performed. The measurements focused on the heat flow of the air, from its sources, to its sink, i.e. compartment. In addition the electrical and mechanical loads of the climate system were included. The different sources of heating and cooling were, for the tested powertrain, waste heat from the engine, a fuel operated heater, heat pickup of the air, evaporator cooling and cooling from recirculation.

The article describes a model-based control method for idle speed of spark-ignition (SI) engines. It is based on mid-ranging, a multivariable control strategy that is more commonly used in process control. The basic building blocks of the control structure are two PI controllers.