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The diversity effectiveness represents the signal improvement by means of an antenna diversity arrangement expressed by an equivalent fictitious number of n decorrelated antennas. With a low-cost compact 4antenna-arrangement on the backlite the diversity effectiveness is considerably higher than with a 2antenna-system with one antenna on each of the front and the back window. This is evaluated from antenna measurements and computer simulation of a Rayleigh field. Further antenna arrangements are discussed. Complex antenna systems of this kind for FM-TV-antenna diversity and AM radio require a device for selftesting of operating functions for OEM production and customer service as well.

Audio demonstration is frequently controlled by the seller. The selling methods used tend to bias the listener toward the seller's system and often mask long-term satisfaction estimates. The paper documents frequently-used selling techniques and offers suggestions for successful auditioning.

The effect of friction modifiers on the low-speed frictional properties of automatic transmission fluids (ATFs) was investigated by scanning force microscopy (SFM). A clutch lining material was covered by a droplet of test ATF, and a steel tip was scanned over the sample. The scanning speeds were varied from 0.13 to 8.56 mm /sec, and the frictional force was deduced from the torsion of the SFM cantilever. A reduction in dynamic friction due to the addition of the friction modifier was clearly observed over the entire speed range. This indicates that the boundary lubrication mechanism is dominant under this condition, and therefore surface-active friction modifiers can effectively improve the frictional characteristics. The friction reduction was more pronounced at lower sliding speeds. Thus addition of friction modifiers produced a more positive slope in the μ-ν (friction vs. sliding speed) plots, and would contribute to make wet clutch systems less susceptible to shudder vibrations.

This paper describes the relationship between the design parameters used to define the geometry of an automotive torque converter and the resultant efficiency in relation to the internal flow characteristics. Taking the turbine bias angle and the contraction ratio of the pump flow passage as specific examples, the effects of each design parameter on the internal flow characteristics and the occurrence of loss were analyzed. A three-dimensional viscous flow analysis code was used in the numerical computation procedure and a method developed independently by the authors was used in the loss analysis. The flow near the wall was visualized experimentally using a technique resembling the so-called oil film method. The visualized results showed good qualitative agreement with the numerical analysis results.

Automatic transmissions equipped with Modulated Torque Converter Clutches (MTCC) require an effective combination of automatic transmission fluid (ATF) - friction material in order to maintain frictional integrity. However, in this study, thermal analysis has shown that ATFs can interact chemically with a friction material used in the MTCC under service conditions, potentially affecting the frictional characteristics. A technique was developed to evaluate friction material degradation. The results of this study showed that the friction material my be chemically altered by static aging in certain ATFs at elevated temperatures. The statically aged friction material samples exhibited thermal analysis signatures which were similar to identical material degraded during dynamometer and fleet vehicle tests. These vehicle tests resulted in deterioration in friction characteristics and experienced shudder.

The approximate torque response model for the engagement of a wet friction clutch, developed by Berger [1, 2], was modified and enhanced. The modified Reynolds equation for the film thickness and force balance for the wet clutch pack are solved numerically. The Reynolds equation relates the film hydrodynamic pressure to the film thickness, physical properties of friction materials, and operating parameters. The torque is calculated from the film and asperity pressure distribution at the friction interface. The applied pressure and the interface temperature as a function of time during engagement are considered in the model. The correct average flow factors of Patir and Cheng [3, 4] for ATF flow between rough surfaces are incorporated into the model. The permeability of friction materials and the temperature gradient inside the friction material are considered.

In this study two planetary gearset pinion needle bearing lubrication methods - forced flow into the bearings and splash lubrication were evaluated for their cooling effectiveness and their potential to improve bearing life. Bearing operating temperatures were measured by placing thermocouples in the support pins. Life tests were then run under “good” and “poor” lubrication conditions to determine the effect of lubrication on bearing life.

Driveline vibration is usually associated with friction clutch dynamics. However, the roller One-Way Clutch (OWC) can also be a source of vibration. The OWC has two basic operational modes: 1) Engaged, and 2) Freewheel. In this paper we will develop a means to predict the freewheel-mode resonant response of a roller OWC system. The study begins by making some fundamental simplifying assumptions, which lead us to an equivalent OWC system spring rate, kowc. The roller OWC system is then modeled as a simple mass-spring-mass system, from which the application of appropriate boundary conditions yield the desired fundamental resonant frequencies. This analysis method is then applied to a number of roller OWC systems, and the results are compared to numerical simulation and experimental results.

Electronic closed loop control of automatic transmission functions can potentially benefit from the use of quantitative models of transmission response in a form compatible with controller design procedures. Transmission dynamic response during gear shifts of a discrete-ratio transmission is nonlinear. Procedures for developing linearized dynamic models are applied to the simulation of the nonlinear model of a representative power train during the inertia phase of a shift. The frequency responses for the resulting linear models are examined, and their implications for controller design are noted.

This paper presents some of the design rules used to calculate critical geometry of engine components, and the object-oriented component hierarchy system in PET. This paper also presents parametric solid model assembling schemes used to dynamically construct an assembly of whole powertrain systems. Some examples of powertrain concept design, such as the estimation of friction, packaging, and moving component clearances, will be presented. The computational efficiency of this concept design method will be compared to traditional methods also.

This paper presents a case study of the development of a new water cooled DOHC cylinder head. This specific head represents the highest geometric complexity, including multiple core cavity structures, in cylinder heads. The goal of this study was to verify the possibility of a paradigm shift in engine development, in which tooling design and production are postponed until after dynamometer testing of the engine is completed. This paradigm shift becomes possible with the use of Direct Shell Production Casting a rapid manufacturing process which makes traditional casting obsolete. Using Direct Shell Production Casting (DSPC®) to produce the prototype cylinder heads and blocks in aluminum and ductile iron enabled the development team to completely eliminate the need for temporary tooling. DSPC works directly off of a CAD file to create the actual ceramic casting molds, complete with integral cores.

Push fit couplings are becoming increasingly popular for vehicle climate control systems due to the simplicity of assembly operations that they allow. An accelerated ageing test has been developed which includes the effect of vehicle vibration and thermal cycles. The couplings include elastomeric seals which after time may age, harden and lose sealing force contact. There can also be some permeation of gas through the seal material although this is usually at a low level which can be calculated provided that the permeation constants for the elastomeric materials have been measured. A novel test rig has been developed which allows 12 couplings to be tested simultaneously. There is continuous monitoring of the amount of gas that leaks past the coupling seals using sensitive transducers on the gas collection cells. A test sequence has been developed which includes a primary period of several days at 120°C followed by a secondary period of a few hours cooling to between -20 or -40°C.

In this paper, the performance of hydro-pneumatic limited bandwidth active suspension system is studied theoretically using a half car model. The bounce and pitch motions for the sprung mass and two vertical degrees of freedom for the unsprung mass's are considered (to permit for good suspension design). The linear optimal control theory is used to derive the full state feedback and feedforward control laws taking into account the correlation between the front and rear wheel excitation. The results are generated when the vehicle running on a statistically random road using a 6 Hz bandwidth analogue controller. A comparison between the conventional passive, limited bandwidth active suspensions with and without wheelbase correlation are presented and discussed. The results showed that there is a worthwhile improvement for the proposed active system over the passive, while incorporating wheelbase correlation added more benefits for the rear axle dynamics and pitch motion.

Along with the rapid improvement in automobile performance, drivers are seeking improvements in the handling stability at high vehicle speeds. Drivers are also seeking light steering effort at low vehicle speeds and parking condition. However, a conventional hydraulic power steering system can not meet both requests (i.e., conflicting issues). To resolve such conflict, we have developed Electronic Controlled Power Steering System. The main developmental goals were: develop low cost and compact system for small passenger vehicles develop an “optimum” control algorithm by using absolute neutral steering angle position and steering angular velocity.

A new active rear steer (ARS) system has been developed. ARS is an electric four wheel steering system controlled by new logic(designed by H∞-μ synthesis) which maintains good control performance even if the vehicle parameters and /or road surface conditions are changed. ARS control is a typical technology to prevent vehicle side -slip in linear region of tire characteristic. This system offers easy control and reduces vehicle behavior of yawing motion before approaching critical limit. By combining ARS and vehicle stability control (VSC), it is possible to support driving precisely from normal driving to excessive driving. This paper describes the details of this new system which has been installed on 1997 model TOYOTA ARISTO for practical use in JAPAN.

The dynamic characteristics of electric power steering (EPS) systems can be characterized by the transmissibility from rack load to steering wheel torque. The transmissibility can be studied by fixing the steering wheel and calculating the frequency response from the rack load to the torque needed to hold the steering wheel. A proportion plus-derivative control is needed for EPS systems to generate desired static torque boost and avoid high transmissibility at the mid-frequency range. A pure proportion control can't satisfy both requirements at the same time.

In recent years improved emissions control, energy saving devices and safety features have become the driving forces in automotive manufacturing and technology. We have developed the Active-Rear-Steer system with an electro-mechanical actuator, which is an improved safety feature. It also features availability to mass production and a compact size. The system is highly responsive, increasing vehicle performance and stability, thus, enhancing the active safety of the vehicle.

This paper investigates the problem of interoperability of ECUs in a distributed control system consisting of a set of ECUs connected by a serial communication channel. If the application tasks executing within an ECU depend on the temporal properties of the data delivered by the communicatioin channel, then a precise specification of the temporal interface properties is a prerequisite for interoperability. Such a precise interface specification can be developed if the communication system is time-triggered and the points in time, when the information is updated at the receivers, is known a priori. In the second part of the paper the concept of a “temporal firewall” is introduced to precisely specify the input and output interfaces of a node in the value domain and the time domain. Examples for temporal firewalls in a distributed vehicle control system are given.

The purpose of this paper is to discuss methods available to designers to suppress ESD and control EMI on automobile multiplexed data lines. Multiplex standards (such as J1850) have created complex networks of sensors and controls within automobiles which are prone to damage by ESD. Further, as communication speeds increase, the networks EMI/RFI performance becomes of greater importance. Both issues must be addressed by designers in order to guarantee long term reliability of the network. There are many methods in which designers have dealt with EMI and ESD transient voltage problems. Some designers used R/C networks, L/C networks or back to back Zeners with an EMI capacitor. Others relied upon internal protection of the IC to handle suppression. A relatively new method utilizing Multilayer Varistors (MLVs) was found to have both electrical and size advantage over most if not all previous suppression/control methods.

As the importance of automotive electronics increases, the task of design and manufacturing becomes more difficult due to the growing number, size, and weight of the wiring harnesses. As an approach to resolve these problems, many multiplexing protocols such as Controller Area Network (CAN), Advanced PALMNET and J1850 have been developed by many automobile companies. In order to compare these protocols quantitatively, this paper presents the performance evaluation of CAN and Advanced PALMNET via discrete event simulation. Through numerous simulation experiments, several important quantitative performance factors such as the probability of a transmission failure, average system delay (data latency), and throughput have been evaluated. In addition to the performance comparison, the effect of data latency on a control system has been shown via simulation.