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Technical Paper

“Zero Defects”, Statistically Considered

The requirement of “zero defects” is rapidly finding its way as a “standard” of quality in numerous quarters. This phrase has great psychological appeal, and is often taken literally at all levels in an organization even though quality motivation may be the intention. It is common to believe that when zero defects are found in the sample, this must be the case for “all the rest” as well. In this paper the technical side of “zero defects” is examined. We look at the statistics of zero defects and show what is implied about lot or process quality when zero defects is the actual sample outcome. The focus is on attribute measurements and includes some special cases where a significant measurement error exists and cases where a Bayesian statistical analysis may be appropriate.
Technical Paper

“Understanding Diesel Engine Lubrication at Low Temperature”

Oil pumpability in passenger car gasoline engines was well-characterized by an ASTM program and by individual researchers in the 1970's and early 1980's. Oil pumpability in diesel engines however, was not investigated to any significant extent until the mid-1980's. This study was initiated to define the performance of several commercial viscosity modifiers in different formulations containing 3 detergent-inhibitor (DI) additive packages and 4 basestock types. The test oils were run at -18°C (0°F) in a Cummins NTC-400 diesel engine. The results, when statistically analyzed, indicated that a new, second generation olefin copolymer (OCP) viscosity modifier had better performance than a first generation OCP and, furthermore, had performance equal to a polymethacrylate (PMA) viscosity modifier. The analysis also showed that one DI/base stock combination had a significant effect on performance.
Technical Paper

“Taguchi Customer Loss Function” Based Functional Requirements

Understanding customer expectations is critical to satisfying customers. Holding customer clinics is one approach to set winning targets for the engineering functional measures to drive customer satisfaction. In these clinics, customers are asked to operate and interact with vehicle systems or subsystems such as doors, lift gates, shifters, and seat adjusters, and then rate their experience. From this customer evaluation data, engineers can create customer loss or preference functions. These functions let engineers set appropriate targets by balancing risks and benefits. Statistical methods such as cumulative customer loss function are regularly applied for such analyses. In this paper, a new approach based on the Taguchi method is proposed and developed. It is referred to as Taguchi Customer Loss Function (TCLF).
Technical Paper

“SODART” Telescope Silicon Detector Cooling System (Thermal Test Results of the Scale-Down Model)

The onboard “SODART” telescope silicon detector cooling system of the “Spectrum-X-Gamma” observatory, which is designed for the space objects X-ray radiation study, is described. The scale-down model of the passive cooling system description and thermal vacuum test results of this model are given. In the real cooling system the minimal detector temperature at 300 mW heat release is expected about 107 K.
Technical Paper

“Rds_on” Based OBD for Pre-Supply Fuel Pump Driver Modules

In automotive electronics on-board diagnostics does the fault diagnosis and reporting. It provides the level of robustness required for the control electronics against various faults. The amount of diagnostic information available via on board diagnostics are depends on the type of vehicle. Pre-supply fuel pump is the component in the common rail hydraulic system. It pumps the fuel from the fuel tank to the inlet valve of the high pressure fuel pump. Electronic control unit synchronizes its operation with high pressure fuel pump. A dedicated driver module in the ECU controls the operation of pre-supply fuel pump. The driver module consist of an ASIC with internal voltage, current monitoring modules for the fault diagnosis and the pre-drivers to control external HS and LS power stages. The software part of the OBD programmed in the internal memory of the ASIC. The “Rds_on” of the power MOSFETs are used for the fault detection purpose.
Technical Paper

“Motion in FEA”: An Innovative Approach for More Physical and More Accurate Vehicle Dynamics Simulation

Vehicle dynamics is a discipline of mechanical engineering that benefited of significant improvements thanks to the progress of computational engineering. Vehicle dynamics engineers are using CAE for the development of a vehicle with MBS and FEA. The concurrent use of these two technologies is a standard in the automotive industry. However the current simulation process is not fully efficient because local geometrical and material nonlinearities are not accurately modeled in classical MBS software. This paper introduces a methodology for vehicle dynamics simulation integrating MBS capabilities in one single nonlinear FEA environment enabling an accurate modeling of nonlinearity in vehicles.
Technical Paper

“Meta-modeling”, Optimization and Robust Engineering of Automotive Systems Using Design of Experiments

This paper describes the application of statistical techniques known as Design of Experiments (D.O.E.) to efficiently use the results of numerical analysis data in order to improve the configuration of automotive systems. The general framework of these techniques is presented in a format aiming at the design engineer as their end user. Besides, a case study is presented with the purpose of illustrating their practical use. The first step of the case study is to build predictive models for the behaviour of the automotive system being developed by means of the Response Surface Method (RSM), using the proper D.O.E. options. Once these predictive models are available, automatic numerical optimization algorithms are used to improve the responses of interest for given operating conditions. Finally, the automotive systems are robust designed taking into account that the operating conditions vary randomly.
Technical Paper

‘Tuning’ the Variable Stiffness Head Gasket an Interactive Computational Approach

Problems of bore distortion, combustion blowby and gasket fatigue in lightweight engine blocks are ultimately related to the gasket sealing pressure distribution. For both conventional embossed steel gaskets and composite ones this distribution can be modified by suitable local changes in gasket stiffness. Current methods of gasket optimization concentrate on large scale iterative finite element analysis of the head/gasket/block system, with major computational costs. We present a more economical alternative in which condensed compliance matrices are obtained either from elementary NASTRAN runs or by experimental means. The algorithm enables the gasket engineer to ‘tune’ the gasket to the desired sealing pressure profile with acceptable stiffness variations.
Technical Paper

µMist® - The next generation fuel injection system: Improved atomisation and combustion for port-fuel-injected engines

The Swedish Biomimetics 3000's μMist® platform technology has been used to develop a radically new injection system. This prototype system, developed and characterized with support from Lotus, as part of Swedish Biomimetics 3000®'s V₂IO innovation accelerating model, delivers improved combustion efficiency through achieving exceptionally small droplets, at fuel rail pressures far less than conventional GDI systems and as low as PFI systems. The system gives the opportunity to prepare and deliver all of the fuel load for the engine while the intake valves are open and after the exhaust valves have closed, thereby offering the potential to use advanced charge scavenging techniques in PFI engines which have hitherto been restricted to direct-injection engines, and at a lower system cost than a GDI injection system.
Technical Paper

recent developments make ENGINEERING SPECIFICATIONS more realistic

SPECIFICATIONS that are realistic for production and result in a product that functions properly can be set with a three-step method evolved from statistical control techniques. The tolerances thus established reduce production costs, as well as costs arising from faulty products, the author states. The author applies the method to a leakage problem encountered on mechanical-hydraulic units. Through the use of statistical control techniques, the cause of the leakage was discovered.
Technical Paper

iLokTM Nut - An Innovative Fastener that Solves a 30 Year Old Problem for Rear Axle Hub Assemblies

Truck and bus manufacturers have been constantly facing an issue to disassemble the rear axle shaft from the hub when transporting the truck from the factory to the dealership. In addition to that, the dealerships have the very same problem every time they have to replace the brake pads in some truck models, which leads to excessive service time, extra costs and aftermarket complaints. The current problematic fastening system is composed by a lock nut, a flat washer and a coned slotted bushing. The concept of this 30 year old design involves the coned slotted bushing being pressed against a tapered hole on the shaft’s flange. After tightening the lock nut, the bushing clamps towards the stud and it gets stuck in between the shaft and the stud generating the problem described above. This paper shows the R&D process that Tekfor used to come up with the 1-piece fastener named iLokTM nut that replaces the problematic 3-piece fastening system.
Technical Paper

eROSITA Camera Low Temperature Thermal Control

eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is a powerful X-ray telescope under development by the Max-Planck-Institut für extraterrestrische Physik (MPE) in Garching, Germany. eROSITA is the core instrument on the Russian SRG1 mission which is planned for launch in 2011. It comprises seven nested Wolter-I grazing incidence telescopes, each equipped with its own CCD camera. The mirror modules have to be maintained at 20°C while the cameras are operated at -80°C. Both, mirrors and CCDs have to be kept within tight limits. The CCD cooling system consists of passive thermal control components only: two radiators, variable conductance heat pipes (VCHP) and two special thermal storage units. The orbit scenario imposes severe challenges on the thermal control system and also on the attitude control system.
Technical Paper

byteflight~A new protocol for safety-critical applications

The permanently increasing number of convenience and safety functions leads to higher complexity of in-car electronics and the rapidly growing amount of sensors, actuators and electronic control units places higher demands on high- speed data communication protocols. Safety-critical systems need deterministic protocols with fault-tolerant behavior. The need for on-board diagnosis calls for flexible use of bandwidth and an ever-increasing number of functions necessitates a flexible means of extending the system. None of the communication solutions available on the market until now (like CAN or TTP) have been able to fulfill all these demands. To solve these problems, BMW together with several semiconductor companies has developed a new protocol for safety-critical applications in automotive vehicles.
Technical Paper

Zth Thermal Modelling of MOSFET in Sub-Milliseconds Range

1 An FEA (Finite Element Analysis) model was developed based on the physical dimension of the MOSFET device to produce a Zth curve closely matching the experimental Zth curve. This Finite Element Analysis model would then be extrapolated down to the region beyond the capability of the hardware of the Zth measurement system
Technical Paper

Zone of Influence of Porous Suction Tubes in Condensing Heat Exchanger for Space Systems

A “next generation” condensing heat exchanger for space systems has to satisfy demanding operational requirements under variable thermal and moisture loads and reduced gravity conditions. Mathematical models described here are used to investigate transient behavior of wetting and de-wetting dynamics in the binary porous system of porous tubes and porous cold plate. The model is based on the Richard's equation simplified for the zero-gravity conditions. The half-saturation distance or the zone of influence of the porous annular suction tubes on the cold-plate porous material will be in the range of 1 to 10 cm for the time scales ranging from 100 to 10,000 seconds and moisture diffusivity in the range of D = 10-4 to 10-6 m2/s.
Technical Paper

Zero-Offset in Transducer Output

Zero-offset in transducer output during airbag noise testing is often observed, but mostly ignored due to the lack of understanding of its causes and implications. In the field of high-g acceleration measurement, this phenomenon is well documented, and is referred to as zeroshift. Zero-offset occurs when a component in the measurement chain is exposed to some unexpected inputs which the component has not been designed to handle. These unexpected inputs can be mechanical, electrical, or optical. How the transducer reacts to such inputs and the amount of zero-offset produced depends on the sensing mechanism, material used, and the design of the component itself. This paper explores the causes of zero-offset from a general perspective, covering the entire measurement chain. Although much of the information and discussions are based on data obtained from acceleration measurement systems, the findings are applicable to other transducer types, such as pressure and acoustic measurements.
Technical Paper

Zero Gases for Emission Monitoring - Production, Storage, Treatment and Usage

Increasingly stringent emission levels require better quality facility gas supplies to enable more precise measurements at low levels and reduce variation in test results. The transient and steady state quality of the “zero gas” used in analyzer calibration will directly affect the level of the readings, while variation in the “zero gas” over time will increase the number of tests needed to meet statistical requirements. Facility zero gas supplies for air and nitrogen, at a minimum, require careful evaluation to confirm that the required gas quality is delivered to the test equipment for the desired instrument accuracy. To move from LEV or ULEV to SULEV analysis, a change in methodology of zero gas generation, delivery and handling may be needed to achieve the desired measurement accuracy and repeatability. Traditional tubing, fittings and handling methods can not only limit the possible gas quality, but also contribute to variation.
Technical Paper

Z-type Schlieren Setup and its Application to High-Speed Imaging of Gasoline Sprays

Schlieren and shadowgraph imaging have been used for many years to identify refractive index gradients in various applications. For evaporating fuel sprays, these techniques can differentiate the boundary between spray regions and background ambient gases. Valuable information such as the penetration rate, spreading angle, spray structure, and spray pattern can be obtained using schlieren diagnostics. In this study, we present details of a z-type schlieren system setup and its application to port-fuel-injection gasoline sprays. The schlieren high-speed movies were used to obtain time histories of the spray penetration and spreading angle. Later, these global parameters were compared to specifications provided by the injector manufacturer. Also, diagnostic parameters such as the proportion of light cut-off at the focal point and the orientation of knife-edge (schlieren-stop) used to achieve the cut-off were examined.