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In recent years, the increased use of electric power steering in vehicles has increased the importance of issues such as making systems more compact and lightweight, and dealing with increased development man-hours. To increase development efficiency, the use of a “Hardware in the loop simulator” (HILS) is being tested to shift from the previous development method that relied on a driver's subjective evaluation in an actual vehicle test to bench-test development. Using HILS enables tasks such as specification studies, performance forecasts, issue identification and countermeasure proposals to be performed at an early stage of development even when there is no prototype vehicle. This report describes a case study of using HILS to solve the issues of reducing the load by adjusting the geometric specifications around the kingpin and eliminating the tradeoff by adding a new EPS control algorithm in order to make the electric power steering (EPS) more compact and lightweight.

We had developed Electric Servo Brake System, which can control brake pressure accurately with a DC motor according to brake pedal force. Therefore, the system attains quality brake feeling while reflecting intentions of a driver. By the way, “Build-up” is characteristics that brake effectiveness increases in accordance with the deceleration of the vehicle, which is recognized as brake feeling with a sense of relief as not to elongate an expected braking distance at a downhill road due to large-capacity brake pad such as sports car and large vehicles. Then, we have applied the optical characteristic control to every car with Electric Servo Brake System by means of brake pressure control but not brake pad. Hereby, we confirmed that the control gives a driver the sense of relief and the reduction of pedal load on the further stepping-on of the pedal. In this paper, we describe the development of brake feel based on the control overview.

Honda's technology applied to CR-Z HEV propulsion system. Presenter Takeo Nishibori, Honda R&D Co., Ltd.

In motorcycles, the mass difference between a vehicle and a rider is small and motions of a rider impose a great influence on the vehicle behaviors as a consequence. Therefore, dynamic properties of motorcycles should be evaluated not merely dealing with a vehicle but considering with a man-machine system. In the studies of a simulation for vehicle dynamics, various types of rider models have been proposed and it has already been reported that rider motions have a significant influence on the dynamic properties. However, the mechanism of the interaction between a rider and a vehicle has not been clarified yet. In our study, we focused on weave motion and constructed a full vehicle simulation model that can reflect the influences of the movements of the rider’s upper body and lower body. To construct the rider model, we first measured the vibrational characteristics of a human body using a vibration test bench.

Downsizing the engine would be an effective means of improving fuel economy and reducing CO2 emissions. In this case, low-speed torque generation can be enhanced through the use of impulse charging technology, a subject attracting the attention of many researchers. This paper reports the basic characteristics of impulse charging identified through research using a single-cylinder test engine, aiming for application of the technology to spark ignition (SI) engines. To ensure the maximum level of volumetric efficiency under impulse charging conditions, two requirements are controlling the timing of switching from a negative to a positive pressure wave while turning its direction at the intake chamber, and maximizing the positive pressure wave.

In this study, we developed a simulation method for rough road running condition to reproduce the behaviors of a vehicle body and to precisely estimate the input loads to the frame. We designed the simulation method focusing on a front fork model and a rider model optimized for this type of analysis. In the suspension model development, we conducted detailed measurement of the suspension characteristics on a test bench. Based on the yielded results, the friction force, as well as the spring reaction force and the damping force, was reproduced in the suspension model. The friction of the suspension varies depending on the magnitude of the reaction force associated with bending and this effect was also implemented in the model. Regarding the rider model, the actual behavior of a rider was investigated through the recorded motion video data and used to define the necessary degrees of freedom.

The mechanism of noise production in engine accessory drive belts was discussed. Applying geometric considerations to the transversal vibration of the belt, which is one cause of belt noise, the research showed that vibration of the belt is affected by fluctuations in the rotational speed of the crankshaft, and that the amplitude of the vibrations fluctuates cyclically. The cycle of this amplitude fluctuation is synchronous with engine speed, and for a 3-cylinder gasoline engine, its frequency is the (1.5*n)th engine rotation order. The spectrum pattern of belt vibration therefore shows components of the natural frequency±(1.5*n)th orders. The research demonstrated that at engine speeds at which the natural frequency±(1.5*n)th orders and the (1.5*n)th order frequencies, the engine excitation orders, are identical, multiple engine orders excite resonance in the belt, producing a high degree of belt vibration.

In the development of sound isolation type generators, a three-division case structure divided into two cool zones and one hot zone was studied. This study was aimed at achieving compatibility between sound isolation and cooling capabilities that are in a trade-off relationship. Sound isolation of 12.1 dB(LWA) was achieved by this structure, while obtaining equivalent cooling capabilities to that of open type generators. As a result of adopting this new generator structure for India domestic consumption, the compliance with the Indian noise regulation phase II was achieved for the first time by a mass produced generator.

We have developed a bench test method to assess driver distraction caused by the load of using infotainment systems. In a previous study, we found that this method can be used to assess the task loads of both visual-manual tasks and auditory-vocal tasks. The task loads are assessed using the performances of both pedal tracking task (PT) and detection response task (DRT) while performing secondary tasks. We can perform this method using simple equipment such as game pedals and a PC. The aim of this study is to verify the reproducibility of the PT-DRT. Experiments were conducted in three test environments in which test regions, experimenters and participants differed from each other in the US, and the test procedures were almost the same. We set two types of visual-manual tasks and two types of auditory-vocal tasks as secondary tasks and set two difficulties for each task type to vary the level of task load.

The use of electric vehicles (EV) is becoming more widespread as a response to global warming. The major issues associated with EV are the annoyance represented by charging the vehicles and their limited cruising range. In an attempt to remove the restrictions on the cruising range of EV, the research discussed in this paper developed a dynamic charging EV and low-cost infrastructure that would make it possible for the vehicles to charge by receiving power directly from infrastructure while in motion. Based on considerations of the effect of electromagnetic waves, charging power, and the amount of power able to be supplied by the system, this development focused on a contact-type charging system. The use of a wireless charging system would produce concerns over danger due to the infiltration of foreign matter into the primary and secondary coils and the health effects of leakage flux.

In brake squeal analyses using FE models, minimizing the discrepancies in vibration characteristics between the measurement and the simulation is a key issue for improving its reproducibility. The discrepancies are generally adjusted by the shape parameters and/or material properties applied to the model. However, the discrepancy cannot be easily adjusted, especially, for the vibration characteristic of the disc model of a motorcycle. One of the factors that give a large impact on this discrepancy is a thermal history of the disc. That thermal history includes the one experienced in manufacturing process. In this paper, we examine the effects of residual stress on the natural frequency of motorcycle discs. The residual stress on the disc surface was measured by X-ray stress measurement method. It was followed by an eigenvalue analysis. In this analysis, we developed a unique method in which the residual stress was substituted by thermal stress.

In designing CVT pulleys, the effect of the fit clearance of the movable pulleys and their stiffness on the transmission efficiency and strength of the metal pushing V-belt is not necessarily clear. The research discussed in this paper introduced a pulley model that defined the pulleys as elastic bodies to a previously developed technology for the prediction of the transmission efficiency of the belts. As a result, it was found that when the fit clearance is reduced, the transmission efficiency of the belt is increased, and the amplitude of stress on the innermost rings and the element neck section is reduced. In addition, it was found that if pulley stiffness was reduced transmission efficiency was also reduced, and the amplitude of stress on the element neck section increased. This indicated that the fit clearance and the pulley stiffness changed the degree of deflection of the pulleys in the axial direction.

This research sought to develop a dynamic charging system, achieving an unlimited EV cruising range by charging the EV at high power during cruising. This system would help make it possible to finish battery charging in a short time by contact with the EV while cruising and enable drivers to freely cruise their intended routes after charging. A simulation of dynamic charging conditions was conducted for ordinary autonomous cruising (i.e., ordinary EV cruising) when dynamically charging at a high power of 450-kW (DC 750 V, 600 A). This report discusses the study results of a method of building the infrastructure, as well as looking at the cruise test results and future outlook. In particular, the research clarified the conditions for achieving an unlimited vehicle cruising range with a 450-kW dynamic charging system. It also demonstrated that this system would allow battery capacities to be greatly reduced and make it possible to secure the battery supply volume and resources.

When a vehicle drives over road seams or a bumpy surface, low-frequency noise called drumming is generated, causing driver discomfort. The generation of drumming noise is closely related to the vibration characteristics of the suspension, body frame, and body panels, as well as the acoustic characteristics of the vehicle interior. It is therefore difficult to take measures to get rid of drumming after the basic vehicle construction has been finalized. Aiming to ensure drumming performance in the drawing review phase, we applied the Finite Element Method (FEM) to obtain acoustical transfer functions of the body, and Multi Body Simulation to get suspension load characteristics. This paper presents the results of the study of drumming prediction technology using this hybrid approach.

The use of low-density materials in body panels is increasing as a measure to reduce the weight of the vehicle body. Honda has developed an aluminum/steel sheet hybrid door that is more effective in reducing weight than an all-aluminum door. Because aluminum was used in the door skin, bimetallic corrosion at the connection between the aluminum and the steel sheets represented an issue. It was possible that the difference in the electrical potential of the two metals might promote corrosion at the connection between the aluminum door skin and the steel sheet door panel, in particular at the lower edge of the door, where rainwater and other moisture tend to accumulate, with the result that the appeal of the exterior of the door might decline.

The strength characteristic of CFRP composite materials is often dependent on the internal micro-structural fracture mode. When performing a simulation on composite structures, it is necessary to take the fracture mode into account, especially in an automobile body structure with a complex three-dimensional shape, where inter-ply fractures tend to appear due to out-of-plane load inputs. In this paper, an energy-based inter-ply fracture model with fracture toughness criteria, and an intra-ply fracture model proposed by Ladeveze et al. were explained. FEM analyses were performed on three-dimensional test specimens applying both fracture models and the simulated results were compared with experimental ones. Reproducibility of the fracture mode was confirmed and the importance of combining both models was discussed.

Metal additive manufacturing has high potential to produce automobile parts, due to its shape flexibility and unique material properties. On the other hand, residual stress which is generated by rapid solidification causes deformation, cracks and failure under building process. To avoid these problems, understanding of internal residual stress distribution is necessary. However, from the view point of measureable area, conventional residual stress measurement methods such as strain gages and X-ray diffractometers, is limited to only the surface layer of the parts. Therefore, neutron which has a high penetration capability was chosen as a probe to measure internal residual stress in this research. By using time of flight neutron diffraction facility VULCAN at Oak Ridge National Laboratory, residual stress for mono-cylinder head, which were made of aluminum alloy, was measured non-distractively. From the result of precise measurement, interior stress distribution was visualized.

According to the North American National Automotive Sampling System Crashworthiness Data System (NASS/CDS), approximately one-half of all accidents during driving are of the secondary collision pattern in which the collision event involves the occurrence of secondary collision. Accidents involving impact to a stopped vehicle (chain-reaction collisions) have increased to approximately 3% of all accidents in North America, and although the rate of serious injury is low, cases have been reported of accidents in which cervical sprain occurs as an after-effect[1]. In order to mitigate these circumstances, research has been conducted on systems of automatic braking for collisions. These systems apply brakes automatically when a first collision has been detected in order to avoid or lessen a second collision. Research on automatic collision braking systems, however, has not examined the multiple collisions parked [1, 2].

At present, measurements of running resistance are conducted outdoors as a matter of course. Because of this, the ambient temperature at the time of the measurements has a considerable impact on the measurement data. The research discussed in this paper focused on the temperature characteristic of the tires and developed a new correction technique using a special rolling test apparatus. Specifically, using a tire rolling test apparatus that made it possible to vary the ambient temperature, measurements were conducted while varying the levels of factors other than temperature that affect rolling resistance (load, inflation pressure, and speed). Next, a regression analysis was applied to the data for each factor, and coefficients for a relational expression were derived, making it possible to derive a quadratic equation for the tire rolling resistance correction formula.

Cabin quietness is one of the important factors for product marketability. In particular, the importance of reducing road noise is increasing in recent years. Methods that reduce acoustic sensitivity as well as those that reduce the force transferred from the suspension to the body (the suspension transfer force) are used as means of reducing road noise. Reduction of the compliance of the body suspension mounting points has been widely used as a method of reducing acoustic sensitivity. However, there were cases where even though this method reduced acoustic sensitivity, road noise did not decrease. This mechanism remained unclear. This study focused on the suspension transfer force and analyzed this mechanism of change using the transfer function synthesis method. The results showed that the balance between the body's suspension mounting points, suspension bush, and suspension arm-tip compliance is an important factor influencing the change in suspension transfer force.