Computer–aided technologies are being actively developed and introduced in the car industry, and are expected to have an increasingly wide range of applications. Among the technologies, this paper focuses on CAD/CAM, CAE, CAT and FA, describing their current status and discussing the direction the technologies will take in response to the progress of the technologies relating to database, network, artificial intelligence and computers. In this paper, computer–integrated manufacturing (CIM) is depicted as a future image of computer–aided technologies. To make CIM a reality, reorganisation of work processes will take on increased importance in addition to improvements in computer systems.
Ensuring indirect rear vision is a most important safety requirement in trucks. As is often experienced, while driving in the rain, especially at high speeds, raindrops adhering to the outside rearview mirror and door window seriously restrict indirect rear vision. In the past there has been no study of the effects on viability of water drops adhering to mirrors and windows or of the cause of this problem. Nor has any attempt been made to present suitable countermeasures. This paper clarifies the effects of cab shape, mirror position, and vehicle speed on raindrops adhering to the outside rearview mirror and door window through tests conducted using an actual truck. A wind tunnel test was also conducted to check the behavior of air and raindrops around the cab and mirror, thereby analyzing how water drops adhere to the mirror. Countermeasures are also presented for the problem. If also deals with the theoretical approach to solving the problem by making a two–dimensional fluid analysis through numerical calculation.
A driving simulator system with audiovisual aids has been developed. The hardware of the system is characterized by analogous models of various mechanical functions on car running characteristics and operation sense with high fidelity. The software of the system is based on the principles of programmed learning. The system teaches the novice driver basic driving skills and the rate of erroneous response is comparable with that of conventional teaching methods at driving schools. The results show that this form of instruction is superior to the conventional one.
Recently, Traction Control System (TCS) which maintains stability and steerability of vehicles on low–μ surface roads, by controlling the slip ratio between tyre and road surface, is attracting attention. In this paper, the control stability analyses of TCS with computer simulations and vehicle tests are described. In the first place, the control stability in the balancing state is examined with a simplified model. Secondly, with a full–vehicle model, the control stability is examined. These results show that the control stability can be improved by adjusting the P–1 control gains, and furthermore, brake application is effective for preventing excessive wheel spin.
The Suzuki optimisation system has been developed to investigate a lightweight vehicle subject to constraints on displacement and eigenfrequency in a simple model. The application of the system to several vehicles with different structures in their early design stage demonstrated that a reduction in structural weight was achievable under most design constraints. As a result, the future applicability of the system over the optimisation of vehicle body structure was confirmed to a certain extent.
An advanced control method for four–wheel–steering vehicles is proposed. The dynamics of this method are designed to follow the performance of a virtual vehicle as a reference model described by the controller. According to theoretical analysis and computer simulation of the driver–vehicle system at high speed, the transient steering response is much improved by feedforward compensation. Furthermore, stability under side wind gusts is greatly improved due to the autonomous steering effect by the feedback compensation for vehicle body fluctuation instead of the driver's feedback compensation.
The vibration and ride–comfort of some heavy duty trucks was analyzed by the simple model developed by finite element method. Ride–comfort of heavy duly trucks is significantly influenced by bending vibration of the frame, so the frame was modeled by a BAR element having a number or different cross sections, so a separate model as a rigid body was established. For non–linear components such as mounting rubber, tyre, leaf spring, the best data from specific areas of vibration were selected for inputting into the model and corrections were added to the model. For modeling check, frequency response of consolidating several kinds of component models was calculated in the initials stage of the system model. Each component model was consolidated with the frame model to obtain the system model. From this system model calculation results of frequency response and PSD response were obtained for making comparison will actual test and were found to be sufficient to make qualitative evaluation of ride–comfort. Consequently this simulation method was used in design stages, such as development or cab–suspension and improvement or ride–comfort of tractor pulling trailer.
The relation between axial forces and their distribution on the pulley for a newly–developed block–type CVT V–belt was studied experimentally. The axial force applied to one block is not constant through the arc of contact even when initial tension only without the transmission power is applied. When the belt is in the pulley, according to the contact progress from the entrance toward the exit, the axial force increases rapidly, and finally it records the highest value at the exit point. From the dynamic test, it was confirmed that this belt has high power transmitting ability notwithstanding its compact form. A modified Ogasawara's equation for predicting the relation between two axial forces was also proposed.
It is the general view in Japan, Europe and North America that hybrid vehicles are a promising energy efficient and low carbon dioxide (CO2) emission vehicle for possible use in the near future. Thus, attention is focused on the development of hybrid vehicles and the verification of their potential. Hybrid vehicle technology has progressed with a great effect on vehicle efficiency, fuel economy and the reduction of CO2 emissions. The efficiency of the future hybrid vehicles under development within the New Energy and Industrial Technology Development Organization (NEDO) Advanced Clean Energy Vehicle Project (ACE) has reached over 45%. The efficiency of these hybrid vehicles is approaching that of advanced fuel cell hybrid vehicles (FC-HVs). Therefore, well to wheel efficiency and CO2 emission levels of these hybrid vehicles have improved by a greater margin than the advanced FC-HVs. Key technologies are high performance motor/generators, new batteries/capacitors and advanced hybrid system configurations/mechanisms with advanced electronic control systems.
The most common mode of deactivation suffered by catalysts fitted to two-stroke engines has traditionally been thermal degradation, or even meltdown, of the washcoat and substrate. The high temperatures experienced by these catalysts are caused by excessively high concentrations of HC and CO in the exhaust gas which are, in turn, caused by a rich AFR and the loss of neat fuel to the exhaust during the scavenging period. The effects of catalyst poisoning due to additives in the oil is often regarded as a secondary, or even negligible, deactivating mechanism in two-stroke catalysts and has therefore received little attention. However, with the introduction of direct in-cylinder fuel injection to some larger versions of this engine, the quantities of HC escaping to the exhaust can be reduced to levels similar to those found on four-stroke gasoline engines. Under these conditions, the effects of poisoning are much more significant to catalyst durability, particularly for crankcase scavenged derivatives which allow considerable quantities of oil to escape into the exhaust in a neat, or partially burned form. In this paper the effects of oil-derived sulphur on catalyst performance are examined using specialised test apparatus. The oil used throughout the study was formulated specifically for a two-stroke engine fitted with direct in-cylinder fuel injection. The sulphur content of this oil was 0.21% by mass and particular attention was paid to the role of this element in the resulting deactivation. The catalyst was also designed for two-stroke applications and contained a high palladium loading of 300g/ft 3 (28g/l) to prolong the life of the catalyst. It was found that the sulphur caused permanent deactivation of the CO reaction and increased the light-off temperature by around 40°C after oiling for 60 hours. This deactivation was progressive and led to a reduction in surface area of the washcoat, particularly in the micropores of around 5A diameter. By using a validated catalyst model the change in surface area of the precious metal was estimated. It was found that the simulated palladium surface area had to be reduced by a factor of around 7.5 to produce the light-off temperature of the deactivated catalyst. Conversely, the light-off temperature of the C 3 H 6 reaction was barely affected by the deactivation.
Various studies were conducted on a PC-based simulator to identify physiological indices that are sensitive to changes in mental workload. The results confirmed that, when mental workload changes, a response can be observed in the tissue blood volume of the nose tip of the test subjects. This paper presents the results of experiments that were conducted to examine whether similar blood volume responses would appear under simulated driving conditions. The results confirmed that the tissue blood volume level was reduced by the increased mental workload imposed by the execution of a subsidiary task, suggesting that the tissue blood volume level can serve as an index for evaluating driver mental workload.
Since it is known that vehicle braking distance depends on the road surface temperature, this study looked at several factors that could conceivably have a major effect on the braking distance. The authors focused attention on the viscous elasticity characteristics of the tire tread compound and developed a method of predicting the braking distance performance over a wide range of road temperatures, based on the results of the viscous elastic characteristics bench testing of the tread compound and also a minimum amount of actual vehicle testing. A comparison of predicted results and actual vehicle test results verified that the temperature dependence of the braking distance showed the same tendencies in both cases. Thus, the authors established a prediction method for braking distance which is applicable over a wide range of road temperatures using a bench test of tread rubber properties.
A series-type hybrid light duty truck with a compressed nitrogen gas (CNG) ceramic engine was selected for this project, which involved development of various electric control systems. The hybrid truck features a heat insulated ceramic engine, an exhaust energy recovery system, a small-scale high-speed generator/motor, and a brake energy recovery system using electric double layer capacitors. When compared to a conventional diesel truck running under the M15 mode, the hybrid truck's fuel economy improved up to 200% and carbon dioxide (CO2) emission decreased by up to 50% or more.
An investigation was conducted of the exhaust gas emissions near an intersection and how they varied according to different ways of going through the intersection (turning right or left or going straight, with and without stopping) by using an on-board measurement system equipped with gas sensors and a Global Positioning System receiver. The emission factors were found to greatly depend on whether the vehicle was idling while waiting to go through the intersection. Emission factors for driving patterns with long idling times were around 10 times larger than those without idling.
The Magic Formula tyre model is typically used in vehicle handling simulations. This paper summarises developments which extend the validity range of the Magic Formula to higher frequencies, short wavelength excitation and rolling over arbitrary three dimensional obstacles. This new tyre model has been validated extensively using experimental results which show that the extended demands can be met. Examples are given, illustrating that the new tyre model can be used successfully in areas normally not associated with a Magic Formula tyre model.
This hybrid system features clutch mechanism, a permanent magnet motor/generator and a rechargeable energy storage system such as electric double layer capacitors as its main components. The implementation of a one-way clutch allows this system to combine the advantages of a single motor/generator with both series and parallel systems to simplify. When starting from a standstill, this system runs in electric mode using the motor alone. When more torque is needed, the engine starts and the system runs in parallel mode using both the motor and engine in tandem. When the driver keeps constant speed, the motor cuts out and this system runs in engine mode using the engine alone and the storage can be recharged with power generated from any surplus engine torque if necessary. During deceleration, the one-way clutch decouples from the power line and stops the engine. This has achieved fuel consumption approximately twice compared with conventional vehicles.
In driver assist systems, cooperation between the human user and the system is important. The trust of the human user in the system is a factor in promoting cooperation. The authors have been researching trust in low-speed adaptive cruise control systems and have found that the degree of trust fluctuates dynamically. The objective of this paper was to clarify the psychology of trust. Some subjective evaluation factors that may affect the degree of trust were examined by factor analysis.
Improving the shift quality of automatic transmissions requires accurate engine speed control. This becomes more difficult, however, as engine load changes and as engines age. Conventional controls cannot ensure accurate controllability. A control system composed of a sliding-mode controller and an adaptive disturbance observer was designed and applied to engine speed control to address these issues. The new control system has high robustness against changes in engine dynamics and an excellent ability to suppress overshoot. In addition, it provides accurate and rapid engine speed control under all engine conditions.
A fully electronically controllable valve-actuator has potentials of improving volumetric efficiency at gas exchange, and of presenting variable compression-ratio. This paper describes a new type of hydro-mechanical position-servo electro-hydraulic valve actuator for a cam-less engine. The piston is positioned hydro mechanical feedback mechanism, which balances the flow rate of the feedback slot to the pilot valve. The feedback-slot opens its area in proportion to the piston displacement. This mechanism succeeds to decelerate the landing-velocity of 0.2m/s at a working speed of 1.0m/s for valve lift of 12mm, and to actuate the valve at a volumetric efficiency of 95% within lag times of opening 18ms and closing 8ms, that is possible to work at an equivalent engine rotational speed of 2100rpm. The actuator is energized by the hydraulic power source of flow-rate of 6.7L/min and pressure of 14MPa.
