Search Results

A new belt-drive continuously variable Transmission (B-CVT) was introduced into the Japanese market in September 1997 by Nissan Motor Co., Ltd. It transmits a maximum torque of 196 Nm and represents a major breakthrough of the torque limit transmitted by B-CVTs, thus opening a new epoch for the automatic transmission. The major features of the CVT are transmission of high torque between a steel belt and pulleys, electronic control of high hydraulic-pressure to pulleys and a torque converter with an electronically controlled lockup clutch engaging at low vehicle speeds. A CVT fluid formulated for this CVT was designed to optimize these features and this paper describes the performance of the CVT fluid in lab-scale tests and an endurance test of the CVT unit. In order to realize high torque transmission between a steel belt and pulleys, high friction between metal/metal contacts is required with normal wear.

The paper describes the activities of the ZF company in the field of continuously variable transmissions, especially for passenger cars in the past, the present and the near future. As an independent supplier of transmissions for the car manufacturers ZF has to be prepared for the questions and demands of the car industry in the near future. The near future is the time for CVT's and the ZF engineers developed a strategy and a program of continuously variable transmissions for every driveline system. This program and strategy is also described in this paper.

This paper concerns research on an emission control system aimed at reducing emission levels to well below the ULEV standards. As emission levels are further reduced in the coming years, it is projected that measurement error will increase substantially. Therefore, an analysis was made of the conventional measurement system, which revealed the following major problems. 1. The conventional analyzer, having a minimum full-scale THC range of 10 ppmC, cannot measure lower concentration emissions with high accuracy. 2. Hydrocarbons are produced in various components of the measurement system, increasing measurement error. 3. Even if an analyzer with a minimum full-scale THC range of 1 ppmC is used in an effort to measure low concentrations, the 1 ppmC measurement range cannot be applied when the dilution air contains a high THC concentration. This makes it impossible to obtain highly accurate measurements. 4.

We have studied the fuel behavior in Port-injection gasoline engines as the following: 1. We have developed a 100%-sampling quantitative analysis method where fuel is sealed up in the intake port and cylinder at a specific point during firing operation, using an engine with intake and exhaust valves that are opened and closed by electronic control. 2. As a result of our analysis of steady and transient state characteristics of fuel behavior using this method, it was verified that the amount of wall-wetting fuel in the port and cylinder is apparently different before and after the warm-up process. As for transient fuel behavior, a delay in fuel transfer has been acknowledged in the amount of wall-wetting fuel not only in the port but also in the cylinder. Different from the existing indirect analysis, this method enables direct measurement of fuel behavior even during the actual firing operation.

The current method for on-board monitoring of catalyst performance involves detecting the degradation in the oxygen storage capacity as the catalyst ages. Inherent in this method is the need to correlate the deactivation in HC perform-ance with oxygen storage capacity. However, as HC standards become more stringent, light off becomes the key factor impacting HC emission levels, and it is increasingly difficult to detect failures in HC performance based on OSC deactivation. A possible approach to address this challenge is to include catalyst formulation as a variable in performing OBD-II calibrations. This study explores the potential for tailoring the OBD-II performance of a catalyst by customizing the PGM/OSC component to give the desired degree of thermal stability. The effects of sulfur and aging conditions are also investigated. The potential for independent adjustment of OSC and HC performance is discussed.

This report describes the creation of anthropometric head forms. These head forms represent the population of U.S. children aged 2 to 18, and they can be used to develop bicycle helmets which fit the entire range of that population. A Cyberware digitizer was used to collect 3-D points on the heads of 1035 children. Six traditionally measured dimensions were also taken. The data were grouped into four size and shape categories. Statistical techniques were used to summarize the shapes of the heads in each of the categories. The resulting three-dimensional forms were physically rendered using an automated milling machine.

This paper describes the development and benchmarking of two ‘automobile fuel tank evaporation control system’ leak detection methods, which include 1) Positive pressure decay and 2) Negative pressure decay. In the past, negative pressure decay was the least expensive method that met the current OBDII requirement for a 1.0mm leak but these systems exhibit deficiencies when attempting a 0.5mm leak test. Positive pressure systems overcome most of these deficiencies but respond too slowly for evaporative control strategies of the future. Testing was done to compare the ability of each system to detect a 0.5mm fuel tank leak under various environmental conditions. It was found that both systems exhibit similar leak detection capability if a specific degree of stability is attained with respect to tank pressure.

The flame propagations in the very first firing and subsequent cycles in an SI engine during cold start were studied to gain a better understanding of reaction fronts associated with liquid fuel (regular unleaded) in the cylinder. This work was performed using the Rutgers high-speed spectral infrared digital imaging system on a single-cylinder engine with optical access. The engine was mounted with a production engine cylinder-head mated with a conventional port fuel injection (PFI) system. In the study, four images in respective spectral bands were simultaneously obtained at successive instants of time during the combustion period, which was done for eight sequential cycles. This multiple-band successive-imaging was repeated in intervals of about two minutes over a period of more than twenty-five minutes after the engine start. During this experiment, the temperature changes at the intake port, the water jacket and the exhaust gas were monitored.

A new adsorber concept has been tested. A zeolite adsorber with a central hole is mounted below the first catalyst, with a second catalyst downstream. During the cold start, when the adsorber is cool and the HC concentration high, HCs are adsorbed from the gas fraction passing through the channels. The small fraction of exhaust gas passing through the hole impinges directly on and heats the second catalyst. The rationale is to design the hole to maximize the second catalyst heating rate, minimize desorption during heat-up and simultaneously keep the HCs which pass through the hole at an acceptably low level. FTP test results on the 3.8 L engine give 0.081 g/mi NMHC with no hole (same as base line) and decrease to 0.056 g/mi NMHC with the hole. This concept exhibits NMHC performance in the LEV range.

This paper will cover the development of a high-performance snowmobile variable speed belt from concept to successful implementation. The paper includes the definition of the extraordinary demands of this extremely high-performance application, formation and membership of the development team (including the dynamic membership of the team as the development phases were achieved), modeling of the drive geometry and discussion of the vast number of design variables which had to be balanced to achieve both superior drive functionality and belt durability. The end product is described in detail to illustrate the technology employed to address the severe conditions to which the belt is exposed. Finally, the paper details the test methods (both field and laboratory) and development of a unique, application specific, test dynamometer to evaluate the various belt attributes.

An analysis method for characterizing fuel behavior during spark-ignition engine starting has been developed and applied to several sets of start-up data. The data sets were acquired from modern production vehicles during room temperature engine start-up. Two different engines, two control schemes, and two engine temperatures (cold and hot) were investigated. A cycle-by-cycle mass balance for the fuel was used to compare the amount of fuel injected with the amount burned or exhausted as unburned hydrocarbons. The difference was measured as “fuel unaccounted for”. The calculation for the amount of fuel burned used an energy release analysis of the cylinder pressure data. The results include an overview of starting behavior and a fuel accounting for each data set Overall, starting occurred quickly with combustion quality, manifold pressure, and engine speed beginning to stabilize by the seventh cycle, on average.

A by-pass zeolite adsorber system consisting of a first catalyst, a by-pass loop containing the zeolite adsorbers followed by a downstream second catalyst was FTP tested using a U.S. vehicle equipped with a 3.8 L, V6 engine. The system exhibited ULEV emissions performance with hydrocarbon adsorption and regeneration (desorption and oxidation) within the FTP cycle and required only a single diversion valve within the exhaust line. Adsorption takes place during the initial 70 seconds of the FTP cycle. The adsorbers were regenerated with the exhaust gas plus injected air.

This paper reports a 2010 study undertaken to determine generic acceleration pulses for testing and evaluating advanced batteries for application in electric passenger vehicles. These were based on characterizing vehicle acceleration time histories from standard laboratory vehicle crash tests. Crash tested passenger vehicles in the United States vehicle fleet of the model years 2005-2009 were used. The crash test data were gathered from the following test modes and sources: 1 Frontal rigid flat barrier test at 35 mph (NHTSA NCAP) 2 Frontal 40% offset deformable barrier test at 40 mph (IIHS) 3 Side moving deformable barrier test at 38 mph (NHTSA side NCAP) 4 Side oblique pole test at 20 mph (US FMVSS 214/NHTSA side NCAP) 5 Rear 70% offset moving deformable barrier impact at 50 mph (US FMVSS 301). The accelerometers used were from locations in the vehicle where deformation is minor or non-existent, so that the acceleration represents the “rigid-body” motion of the vehicle.

A novel approach to control the output voltage of the generator on a hybrid electric vehicle is proposed in this paper. In addition to the voltage control, for safety reason, it is desirable to control the current of the generator when the machine is running. In order to control the current, the reference voltage is translated to reference current by an estimator. Then current convergence is ensured by controlling the excitation voltage. Thus the over-current is prevented in the system. The rate of convergence of the voltage tracking is discussed. Robustness of the control algorithm against parameter variation is also analyzed and compared with conventional approach. Simulation results show that the safety objective is achieved without sacrificing output performance of the generator.

The mass ratio of air to fuel (air-fuel ratio) of an operating internal combustion engine is a very important metric for pollution control. Typically the air-fuel ratio is not directly measured, but instead the excess air factor Lambda (λ) is used. Lambda is the ratio of actual air-fuel ratio to the stoichiometric air-fuel ratio. Commonly switching type sensors are used. Those can detect 3 states: λ =1, λ >1 and λ < 1, and are used under low and medium load conditions to keep λ in the optimum operating range for a catalytic converter. Wideband O2 sensors are exhaust analysis devices that are used to measure air-fuel mixtures over a very large range up to air. These sensors are used in more and more engines today for closed loop fueling control under all operation conditions. They are especially important for new lean-burn technologies, clean diesel applications and for alternative fuel engines.

Automotive crankshafts are subjected to fluctuating torques due to periodic explosions in the cylinders. Accurate three dimensional finite element modeling is often time consuming. The present research aims to reduce the pre-processing efforts by developing parametric software. A three-dimensional parametric finite element model of crankshaft is developed using brick and wedge elements. Crankshaft main journal bearings are modeled as linear springs and dashpots. The piston and reciprocating masses are lumped at the ends of the crank pins. Viscous damper as well as shaft material damping has been modeled. Results from the three-dimensional analysis have been compared with those obtained using beam element models to assess the capabilities and limitations of such simplified models. It has been demonstrated that the simplified beam element models result in significant errors and 3-dimensional finite element analysis is essential for accurate predictions.

The first-ever application of a hydrogen-free diamond-like carbon (H free DLC) coating to a mass-production gasoline engine reduces friction between the cylinder bore and piston by 18%. It is explained the reducing friction effect of H free DLC by oil film thickness of piston ring. When H-free DLC is applied to top ring, friction is over 10% reduced. Because low friction coating is effective in a thin oil film at a large area near top dead center (TDC). It is also found that the friction reduction effect is enhanced when low viscosity engine oil is used. DLC as a low friction coating is more effective in a thinner oil film. In this study, the adhesion strength of H-free DLC coating on piston rings is improved because of providing a smooth substrate, the new washing process and the optimized coating characteristics. Adhesion strength is verified by test results using actual parts considered to contribute to piston ring load.

In this paper, the effect of welded joints on the crashworthiness response of a hybrid system is presented. This hybrid system consists of a steel enclosure filled with different core materials: carbon-fiber reinforced polymer, glass-fiber reinforced polyamide, polyethylene terephthalate foam and natural cork conglomerate. The metallic enclosure is a cold-formed tube which has to be spot-welded to assemble the final design. The focus is set on the assessment of the effect of the pattern and the number of spot welds on the crashworthiness results in terms of absorbed energy. Results show that variations in the number or the geometric distribution of the spot welds have a direct and noticeable effect on the final amount of energy that the part can dissipate. This is due to the crushing mechanism of the metallic column which is highly sensitive to the way that cold-formed sections are joined.

Conventionally, the automotive outer panels, giving vehicle its shape, have been manufactured from steel sheets. The outer panels are subjected to loads due to wind loading, palm-prints, person leaning on the vehicle, cart hits, and hail stones for example. Consumer awareness about these two panel characteristics: Oilcanning and Dent resistance is increased, which has been observed in recent marketing studies. Apart from perceptive quality, another factor depending on the dent performance is insurance and respective cost implications. Dents can occur due to several reasons such as object hits, parking misjudgement, hail stones etc. Phenomenon can be divided into two types, static and dynamic denting. Static dent case covers scenario wherein interaction with outer panel is mostly quasi-static. Hail stones present dynamic case where object hits a panel with certain kinetic energy. Automotive companies usually perform static dent assessment to cover all the cases.