Search Results

While striving for more fuel-efficient vehicles, all possible measures are considered to increase the efficiency of the combustion engine powertrain. 48V mild hybrid technology is one such measure, SIDI (Spark Ignited Direct Injection) engines with Miller technology are another, while recovering energy from the engine’s waste heat (WHR) is yet another option. In this paper, results will be published from an advanced engineering project at Volvo Cars including all of these components. An ethanol based Organic Rankine Cycle (ORC) WHR-system was successfully built around a 4-cylinder, 2.0 litre SIDI-engine, including 48V mild hybrid technology, with vehicle packaging considered. A dedicated control system was also developed for the ORC system including communication between it and the engine. The ORC system uses the engine exhaust as the heat source, for which a purpose-built evaporator was designed and built to fit in the vehicle tunnel.

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.

The principles of an electronic nose are described briefly. It is shown how a sensor array in combination with pattern recognition software can be used for quality control and classification of car interior trim materials. Anomalies such as bad smelling leather and carpet are shown as outliers. The results are consistent with GC-MS TVOC measurements as well as with data from a human sensory panel. More needs to be done, however, regarding the sensor stability in particular before the sensor array can be used for routine classification of the trim materials.

An acoustic one-dimensional compressor model has been developed. This model is based on compressor map information and it is able to predict how the pressure waves are transmitted and reflected by the compressor. This is later on necessary to predict radiated noise at the intake orifice. The fluid-dynamic behavior of the compressor has been reproduced by simplifying the real geometry in zero-dimensional and one-dimensional elements with acoustic purposes. These elements are responsible for attenuating or reflecting the pressure pulses generated by the engine. In order to compensate the effect of these elements in the mean flow variables, the model uses a corrected compressor map. Despite of the fact that the compressor model was developed originally as a part of the OpenWAM™ software, it can be exported to other commercial wave action models. An example is provided of exporting the described model to GT-Power™.

The low frequency acoustic response of the passenger compartment (cavity) in sedans is considered with respect to the coupling between the cavity and the trunk. Both acoustic (via holes in the parcel shelf or behind the backrest of the rear seat), and structural (via the parcel shelf itself, or the panel of the backrest) mechanisms are investigated by both test and CAE. It is found that the peaks in acoustic response of the cavity at low frequencies are due to both acoustic and structural phenomena. However, the acoustic ones can be effectively blocked by proper design of the trim. Recommendations concerning modeling of acoustic effects in sedans are formulated.

This paper describes how simultaneous numerical simulation of cooling performance and aerodynamic drag can be used to achieve attribute-balanced solutions. Traditionally at Volvo, evaluation of cooling performance and aerodynamics are done by separate teams using separate models and software. However, using this approach, any project changes can be evaluated in terms of their effect on cooling performance and drag from one single model. This enables the project to make decisions that are optimal in a more global perspective. If several proposals have similar levels of cooling performance, the proposal that yields the lowest overall drag can be chosen, thus reducing the fuel consumption of the vehicle. The first part of the paper discusses the prerequisites for the method in terms of boundary conditions, mesh and solution strategy. For the cooling performance part, the importance of high quality boundary conditions is reviewed.

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.

Audio CAE is an emerging area of interest for vehicle OEMs. Questions regarding early stages of the vehicle design, like choosing the possible positions for speakers, deciding the installation details that can influence the visual design, and integration of the low frequency speakers with the body & closures structure, are of interest. Therefore, at VCC, the development of the CAE methodology for audio applications has been undertaken. The key to all CAE applications is the loudspeaker model made available in the vibro-acoustic software used within the company. Such a model has been developed, implemented and verified in different frequency ranges and different applications. The applications can be divided into the low frequency ones (concerning the installation of woofers and subwoofers), and the middle/high frequency ones (concerning the installation of midrange and tweeter speakers). In the case of the woofer, it is the interaction with the body vibration that is of interest.

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.

A two-state forward dynamic programming algorithm is evaluated in a series hybrid drive-train application with the objective to minimize fuel consumption when look-ahead information is available. The states in the new method are battery state-of-charge and engine speed. The new method is compared to one-state dynamic programming optimization methods where the requested generator power is found such that the fuel consumption is minimized and engine speed is given by the optimum power-speed efficiency line. The other method compared is to run the engine at a given operating point where the system efficiency is highest, finding the combination of engine run requests over the drive-cycle that minimizes the fuel consumption. The work has included the engine torque and generator power as control signals and is evaluated in a full vehicle-simulation model based on the Volvo Car Corporation VSIM tool.

A design method for ultra-dependable control-by-wire systems is presented here. With a top-down approach, exploiting the system's intrinsic redundancy combined with a scalable software redundancy, it is possible to meet dependability requirements cost-effectively. The method starts with the system's functions, which are broken down to the basic elements; task, sensor or actuator. A task graph shows the basic elements interrelationships. Sensor and actuator nodes form a non-redundant hardware architecture. The functional task-graph gives input when allocating software on the node architecture. Tasks are allocated to achieve low inter-node communication and transient fault tolerance using scalable software redundancy. Hardware is added to meet the dependability requirements. Finally, the method describes fault handling and bus scheduling. The proposed method has been used in two cases; a fly-by-wire aircraft and a drive-by-wire car.

Thermographic phosphors thermometry was used to measure engine valves and transparent piston temperatures in two dimensions as well point wise of a running, optically accessible, gasoline direct injection engine. The engine, fueled with isooctane, was operated in continuous and skip-fire mode at 1200 and 2000 rpm. A calibration of the phosphorescence lifetime and spectral properties against temperature allowed temperature measurements between 25 and 600°C. Results from the measurements show the potential of the technique for two-dimensional mapping of engine walls, valves and piston temperatures inside the cylinder.

This paper describes the development of a robust and accurate method to model one-phase heat exchangers in complete vehicle air flow simulations along with a comprehensive comparison of EFD and CFD results. The comparison shows that the inlet radiator coolant temperatures obtained with CFD were within ±4°C of the experimental data with a trend in the differences being dependent on the car speed. The relative differences in cooling air mass flow rates increase with increasing car speed, with CFD values generally higher than EFD. From the investigation, the conclusion is that the methodology and modeling technique presented offer an accurate tool for concept and system solutions on the front end design, cooling package and fan. Care must be taken in order to provide the best possible boundary conditions paying particular attention to the heat losses in the engine, performance data for the radiator and fan characteristics.

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.

This paper gives details of the drag and dirt deposition mechanisms related to rear view mirrors. The major design parameters affecting mirror-generated drag and dirt deposition are described. A detailed analysis of the mirror noise properties is not covered for reasons of brevity. A range of test methods is also described which can be successfully used in the mirror optimisation process. The detailed drag breakdown of several rear view mirrors has been made by use of a combination of balance and pressure measurements. The drag breakdown gives an insight into the drag mechanisms and identifies the critical geometry parameters. It is concluded that the relatively high level of drag experienced by some of today's mirrors is primarily the result of premature tip separation and/or an unnecessarily large mirror foot. A level of drag close to the minimum possible, for a given mirror glass area, can be achieved by optimisation of the tip and foot areas.

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.

The automotive industry strives to develop high quality vehicles in a short period of time that satisfy the consumer needs and stand out in the competition. Full exploitation of simulation and Computer-Aided Engineering (CAE) tools can enable quick evaluation of different vehicle concepts and setups without the need of building physical prototypes. Addressing the aforementioned statements this paper presents a method for optimising the Electric Power-Assisted Steering (EPAS) ECU parameters employing solely CAE. The objective of the optimisation is to achieve a desired steering response. The developed process is tested on three specific steering metrics (friction feel, torque build-up and torque deadband) for two function parameters (basic steering torque and active return) of the EPAS. The optimisation method enabled all metrics to fall successfully within the target range.

In 1993 new European legislation regarding side-markers for passenger cars became effective. Volvo requested the TNO-Human Factors Research Institute (HFRI) to investigate the possible safety benefit of this European side-markers configuration. A test panel at TNO- HFRI was used to determine the difference in response time and detection error of drivers, confronted with slides of vehicles with and without the mentioned new vehicle side-marker configuration in several visibility conditions, crossing illumination and different vehicle approach angles. The investigation showed a significant faster vehicle recognition with less detection errors in case the approaching car was equipped with the bright amber side-markers. This improved vehicle conspicuity can be a benefit in crash avoidance, especially when the driver approaches a crossing with complex light environment and reduced visibility.