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Engineers doing squeak and rattle testing of instrument panels (IP's) have successfully used large electrodynamic vibration systems to identify sources of squeaks and rattles (S&R's). Their successes led to demands to test more IP's, i.e., to increase throughput of IP's to reflect the many design, material, and/or manufacturing process changes that occur, and to do so at any stage of the development, production, or QA process. What is needed is a radically different and portable way to find S&R's in a fraction of the time and at lower capital cost without compromising S&R detection results.

The present study investigates the wave propagation and attenuation in catalytic converters. The relationships for wave propagation in a catalytic monolith are derived first and then coupled to the wave propagation in tapered ducts. Analytical predictions are compared with experimental results to validate the theory.

Panel acoustic contribution analysis (PACA) is an advanced engineering tool to improve the NVH quality of vehicles. Using PACA areas of vehicle body panels are categorized according to their contribution to the total sound. Positive contribution areas increase the sound level as vibration amplitude increases, negative contribution areas decrease the sound level as vibration amplitude increases, and neutral areas have no significant effect on the sound level. This knowledge is important to guide vehicle NVH refinement. This paper presents the technical approach of PACA and the results of an experiment used to validate the PACA techniques. Vehicle application results to improve NVH quality and reduce weight are also included.

Intake and exhaust valve control has been combined with engine calibration control by an on-board computer to achieve a Variable Displacement Engine with improved BSFC during part throttle operation. The advent of the on-board computer, with its ability to provide integrated algorithms for the fast accurate flexible control of the entire powertrain, has allowed practical application of the valve disabler mechanism. The engine calibration basis and the displacement selection criteria are discussed, as are the fuel economy, emissions and behavior of a research vehicle on selected drive cycles ( Metro, Highway and Steady State ). Additionally, the impact upon vehicle driveability and other related subsystems ( e.g., transmission ) is addressed.

A series of tests were conducted to determine the potential for reducing vehicle underhood temperatures by either 1) diverting the radiator fan air flow from the engine compartment or 2) by forced air cooling of the exhaust manifold in conjunction with shielding it or 3) by a combination of the two methods. The test vehicle was a Ford F-250 Light Truck with a 7.5L V-8 engine. The vehicle was tested in a dynamometer cell equipped with cell blowers to simulate road speed conditions. It was found that diverting the outlet air from the radiator will reduce underhood component temperatures when the vehicle is in motion and also at normal idle. However, if the vehicle is to be used for power takeoff applications requiring a “kicked” idle, then forced cooling of the exhaust manifolds is also required to maintain reduced underhood temperatures. A combination of these two techniques maximized the reduction of underhood temperatures for all operating conditions tested.

Exhaust pressures (P3) are hard parameters to measure and can be readily estimated, the cost of the sensors and the temperature in the exhaust system makes the implementation of an exhaust pressure sensor in a vehicle control system a costly endeavor. The contention with measured P3 is the accuracy required for proper engine and vehicle control can sometimes exceed the accuracy specification of market available sensors and existing models. A turbine inlet exhaust pressure observer model based on isentropic expansion and heat transfer across a turbocharger turbine was developed and investigated in this paper. The model uses 4 main components; an open loop P3 orifice flow model, a model of isentropic expansion across the turbine, a turbine and pipe heat transfer models and an integrator with the deviation in the downstream turbine outlet parameter.

Speciated HC emissions from the exhaust system of a production engine without an active catalyst have been obtained with 3 sec time resolution during a 70°F cold start using two control strategies. For the conventional cold start, the emissions were initially enriched in light fuel alkanes and depleted in heavy aromatic species. The light alkanes fell rapidly while the lower vapor pressure aromatics increased over a period of 50 sec. These results indicate early retention of low vapor pressure fuel components in the intake manifold and exhaust system. Loss of higher molecular weight HC species does occur in the exhaust system as shown by experiments in which the exhaust system was preheated to 100° C. The atmospheric reactivity of the exhaust HC emissions for photochemical smog formation increases as the engine warms.

The recent development of TiAl-based alloys by the aerospace community has provided an excellent material alternative for hot components in automotive engines. The low density combined with an elevated temperature strength similar to that of Ni-base superalloys make TiAl-based alloys very attractive for exhaust valve applications. Lighter weight valvetrain components improve performance and permit the use of lower valve spring loads which reduce noise and friction and enhance fuel economy. However, difficult fabricability and a perception that TiAl alloys are high cost, low volume aerospace materials must be overcome in order to permit consideration for use in high-volume automotive applications. This paper provides a comparison of properties for several exhaust valve alternative materials. The density of TiAl alloys is lower than Ti alloys with creep and fatigue properties equivalent to IN-751, a current high performance exhaust valve material.

Structural composite materials offer automotive engineers an excellent opportunity to produce automotive components that achieve weight savings, improved NVH (noise, vibration, and harshness) and inherent corrosion protection. Components designed and fabricated from automotive structural composite systems have demonstrated these capabilities during laboratory and in-service durability testing. Components evaluated to date have been employed in areas of the vehicle not likely to encounter high temperatures and with controlled exposure to harsh environments. More extensive use of structural composites will demand that future structural components be located in areas where they will likely encounter a wider range of temperature extremes as well as increased exposure to various environmental and automotive fluids.

A simple CAE method of predicting the performance of a component during sine testing has been developed and applied to the practical case of an automotive component. The slow frequency sweep rate during a test is represented as a sequence of steady state conditions. Direct frequency response analysis at the limited number of frequencies is conducted and results used as a basis for prediction of fatigue damage using the Palmgren-Miner rule. The total damage during the test is calculated by linear summation of the damage during each frequency interval. This technique is completely general and can be applied even if there are multiple inputs to the component. A simple extension enables application to engine testing and other cases where excitation may be expressed as a Fourier series expansion of periodic excitations.

As the compliance with noise legislation became more difficult, Ford exhaust system development engineers increasingly encountered variances not only from vehicle-to-vehicle, but on the same vehicle tested in different locations. As a result, a series of tests were conducted to establish the correlation among various sites for vehicle exterior noise measurements. The purpose of this paper is to present the results and the method developed to achieve the correlation in terms of the following: 1. Ford and site equipment differences 2. Driver differences 3. Differences between site physical qualities Seven sites were evaluated in the program where seven vehicles were used with a good spread in exterior noise levels. A representative correlation plot is also presented which can be used to predict the expected noise level of any vehicle at any one of these test sites knowing the level obtained at the Ford site.

New European emissions legislation (Euro5) specifies a limit for Particle Number (PN) emissions and therefore drives measurement of PN during vehicle development and homologation. Concurrently, the use of biofuel is increasing in the marketplace, and Euro5 specifies that reference fuel must contain a bio-derived portion. Work was carried out to test the effect of fuels containing different levels of Fatty Acid Methyl Ester (FAME) on particle number, size, mass and composition. Measurements were conducted with a Cambustion Differential Mobility Spectrometer (DMS) to time-resolve sub-micron particles (5-1000nm), and a Horiba Solid Particle Counting System (SPCS) providing PN data from a Euro5-compliant measurement system. To ensure the findings are relevant to the modern automotive business, testing was carried out on a Euro4 compliant passenger car fitted with a high-pressure common-rail diesel engine and using standard homologation procedures.

The Ford Motor Company Advanced Engineering Center contains 100,000 square feet of sound and vibration laboratories, induding full vehicle chassis dynamometers, powertrain dynamometers, and sound quality evaluation chambers. The facility houses the first U.S. All-Wheel-Drive NVH Chassis Dynamometer (4 independent motor drive), the first U.S. All-Wheel-Drive NVH Powertrain Dynamometer (4 independent motor drive) and other unique elements, such as innovative wedge construction for the acoustic chambers.

Seat Effective Amplitude Transmissibility (SEAT) values can be obtained from direct measurements at seat track and top or estimated from transmissibility data and seat track input. Vertical transmissibility was measured for sixteen seats and six subjects on the Ford Vehicle Vibration Simulator, and these 96 functions used to estimate the seat top response for rough road input. SEAT values were calculated, and good correlation to values computed from direct seat top measurements obtained (R2 of 0.86). Averaging transmissibilities and direct seat measurements over the 6 subjects to obtain correlations for the 16 seats improved R2 to 0.94, validating this approach.

A laboratory study was performed to assess the effects of sulfur poisoning and desulfation temperature on the NO conversion of a LNT+(Cu/SCR) in-situ system. Four LNT+(Cu/SCR) systems were aged for 4.5 hours without sulfur at 600, 700, 750, and 800°C using A/F ratio modulations to represent 23K miles of desulfations at different temperatures. NO conversion tests were performed on the LNT alone and on the LNT+SCR system using a 60 s lean/5 s rich cycle. The catalysts were then sulfur-poisoned at 400°C and desulfated four times and re-evaluated on the 60/5 tests. This test sequence was repeated 3 more times to represent 100K miles of desulfations. After simulating 23K miles of desulfations, the Cu-based SCR catalysts improved the NO conversion of the LNT at low temperatures (e.g., 300°C), although the benefit decreased as the desulfation temperature increased from 600°C to 800°C.

High mileage NVH performance is one of the major concerns in vehicle design for long term customer satisfaction. Elastomeric components such as suspension bushings, engine mounts and tires function as vibration isolators in a vehicle. High mileage tends to cause the degradation of these components which in turn affects vehicle overall NVH performance. The present paper discusses the characteristics of bushing degradation based on laboratory bushing test data. Vehicle subjective evaluation and CAE modeling methods are used to develop a fundamental understanding of the effects of bushing degradation on vehicle NVH performance. The concept and analysis methodology are demonstrated using the front and rear suspension strut mounts and tire inputs which simulate road excitations but they are valid for other elastomeric components such as engine mounts and excitations. The knowledge derived in the study can be used as a generic guideline in designing vehicles for high mileage NVH robustness.

The variation in the decoupling effect of exhaust flexible couplings under a vertical preload caused by changes in the direction of the exhaust pipe routing was investigated. Both self-supporting and underbody flexible couplings were tested. The results indicate that, in general, a preload decreases the decoupling efficiency of both types of flexible couplings. In addition, the results indicate that the efficiency of the flexible coupling is effected by the following three conditions: the direction of preload with respect to gravity, the location of the preload relative to the coupling, and the stiffness of the various components of the flexible coupling.

Sound attenuation and flow loss reduction are often two competing demands in vehicle breathing systems. The present study considers a full vehicle exhaust system and investigates both the sound attenuation and the flow performance of production configurations including the catalyst, the resonator, and the muffler. Dynamometer experiments have been conducted with a firing Ford 3.0L, V-6 engine at wide-open throttle with speeds ranging from 1000 to 5000 rpm. Measurements including the flow rates, the temperatures and the absolute dynamic pressures of the hot exhaust gases at key locations (upstream and downstream of every component) with fast-response, water-cooled piezo-resistive pressure transducers facilitate the calculation of acoustic performance of each component, as well as the determination of flow losses caused by these elements and their influence on the engine performance.

Validation of the Ford General Engine SIMulation program (GESIM) with measured firing data from a modified single cylinder Ricardo HYDRA research engine is described. GESIM predictions for peak cylinder pressure and burn duration are compared to test results at idle operating conditions over a wide range of valve overlap. The calibration of GESIM was determined using data from only one representative world-wide operating point and left unchanged for the remainder of the study. Valve overlap was varied by as much as 36° from its base setting. In most cases, agreement between model and data was within the accuracy of the measurements. A cycle simulation computer model provides the researcher with an invaluable tool for acquiring insight into the thermodynamic and fluid mechanical processes occurring in the cylinder of an internal combustion engine.

An advanced diesel aftertreatment system utilizing Selective Catalytic Reduction (SCR) with urea for lean nitrogen oxides (NOx) control was tested on a 2.7L V6 Land Rover vehicle to demonstrate the capability of achieving Tier 2 Bin 5 and lower emission standards for light-duty trucks. SCR washcoat was applied to a diesel particulate filter (DPF) to perform NOx and particulate reduction simultaneously. Advanced SCR systems employed both traditional SCR catalysts and SCR-coated filters (SCRF) to improve the NOx reduction efficiency. The engine-out NOx level was adjusted by modifying the EGR (Exhaust Gas Recirculation) calibration. Cold start NOx performance was improved by SCR warm-up strategy and urea over injection. This study showed the advanced SCR system could tolerate higher NH₃ storage in the SCR catalyst, resulting in overall higher NOx conversion on the FTP-75 test cycle.