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When evaluating the wear properties of slide bearings for car engines, it is a common practice to conduct long-term physical test using a bearing tester for screening purposes according to the revolution speed of the shaft, supply oil temperature and bearing pressure experienced in the actual use of engines. The loading waveform applied depends on the capability of the tester that is loaded, and it is often difficult to apply a loading waveform equivalent to that of actual engines. To design an engine that is more compact or lighter, it is necessary to reduce the dimensions of slide bearings and the distance between bearings. This requires loading tests on a newly designed engine by applying a loading waveform equivalent to that of actual engines to slide bearings and their vicinity before conducting a firing test. We therefore conducted an engine firing test by attaching thin-film sensors to the slide bearing part of the engine and measured the actual load distribution.

When a vehicle is cruising, unpleasant noise in the 4 to 5 KHz high-frequency band can be heard at the center of all seats in the vehicle cabin. In order to specify the source of this noise, the correlation between the noise and airborne noise from the outer surface of the transmission was determined, and transfer path analysis was conducted for the interior of the transmission. The results indicated that the source of the noise was the 0th-order breathing mode specific to the drive motor. To make it possible to predict this at the desk, a vibrational analysis method was proposed for drive motors made up of laminated electrical steel sheets and segment-type coils. Material properties data for the electrical steel sheets and coils was employed in the drive motor vibrational analysis model without change. The shapes of the laminated electrical steel sheets and coils were also accurately modeled.

At present, biodiesel fuels using natural-origin materials are expanding in share, and there are many different kinds. Biodiesel fuel generates organic acid when it deteriorates, so care is needed when evaluating the influence of the fuel on automotive fuel-line materials. A model biodiesel fuel was designed taking into account deterioration of the fuel and mixing of impurities into it. Durability of automotive fuel-line rubber and plastic materials were evaluated by using the model fuel. From the evaluation results, it was found that fluoroelastomer (hereafter referred to as FKM) and polyacetal resin (hereafter referred to as POM) deteriorate depending on specific fuel properties and deterioration state. In this paper, we report evaluating results of biodiesel fuels on the automotive fuel-line rubber and plastic materials, and the importance of biodiesel fuel property management.

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.

Honda announced an independent right and left rear toe control system (first generation) in 2013 and presented it as the world's first. As stated in a previous paper, “Independent Left and Right Rear Toe Control System,” with this system Honda has achieved a balance between an enjoyable driving experience in which handling is performed at the driver's will (“INOMAMA” handling) and stable driving performance.(1) This first generation is optimally designed to the vehicle specifications such as suspension axial force and steering gear ratio of the vehicle to which the system is applied. For more widespread application of independent rear toe control technology, a next generation system (second generation) has been developed, which achieves both cost reduction and flexible system performance which can be adapted to a variety of vehicles. The system development began by setting the required target performance with consideration for adaptation to various car models.

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.

When the strain is temporarily stopped during tensile testing of a metal, a stress relaxation phenomenon is known to occur whereby the stress diminishes with the passage of time. This phenomenon has been explained as the change of elastic strain into plastic strain. A technique was devised for deliberately causing strain dispersion to occur by applying the stress relaxation phenomenon during stamping. A new step motion that pause the die during forming was devised; it succeeded in modifying the deep-draw forming limit by a maximum of 40%. This new technique was verified through tensile and actual stamping tests. It was confirmed that the use of step motion causes the strain to disperse, thereby modifying the deep draw forming limit. The degree to which the forming limit is modified is dependent on the stop time and the temperature. Step motion technology increases the stampability of high-strength, forming-resistant materials and allows for expanded application of these materials.

In our preceding report [1], we showed that the thermal conductivity of a heat pipe dramatically improves during high-speed reciprocation. However, this cooling method has rarely been applied to car engine pistons because the thermal conductivity of commercially available heat pipes does not increase easily even if the pipe is subjected to high-speed reciprocation. In consideration of the data from our preceding report, we decided to investigate heat pipe designs for car engine pistons, propose an optimum design, and conduct thermal analysis of the design. As a result, we found that it is possible to transport heat from the central piston head area, where cooling is most needed, to the piston skirt area, suggesting the possibility of efficient cooling.

Car engine piston cooling is an important technology for improving the compression ratio and suppressing the deformation of pistons. It is well known that thermal conductivity improves dramatically through the use of heat pipes in computers and air conditioners. However, the heat pipes in general use have not been used for the cooling of engines because the flow of gas and liquid is disturbed by vibration and the thermal conductivity becomes excessively low. We therefore developed an original heat pipe and conducted an experiment to determine its heat transfer coefficient using a high-speed reciprocation testing apparatus. Although the test was based on a single heat pipe unit, we succeeded in improving the heat transfer coefficient during high-speed reciprocation by a factor of 1.6 compared to the heat transfer coefficient at standstill. This report describes the observed characteristics and the method of verification.

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.

An examination was made on the effect of low-viscosity engine oil on fuel efficiency improvements and engine reliability for the purpose of improving fuel efficiency through the use of select engine oils. Fuel efficiency-improving effects were estimated by measuring friction torque using low-viscosity engine oil. The results show that reducing engine oil viscosity is effective for improving fuel efficiency. In examining engine reliability, attention was paid to the following two aspects which are concerns in practical performance that may arise when engine oil viscosity is reduced. Engine oil consumption Sliding wear at high temperatures Tests and analyses were conducted to develop indexes for engine oil properties that are strongly correlated with each of these two concerns. A strong correlation was found between engine oil consumption and the results of a thermogravimetric analysis, and between high-temperature sliding wear and high-temperature, high-shear viscosity (HTHS).

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.

To increase the durability of multiple-plate clutches used in automatic transmissions, attention was focused on the wear history of the facing material. Measurements have confirmed that correlations can be observed between initial wear and disk contact pressure when the clutch is engaged, and between steady wear and plate temperature. Next, simulation technology was developed to quantify the disk contact pressure and plate temperature. When simulated contact pressure distribution and temperature distribution were used to establish correlations with durability wear, good proportional relationships were found in both cases. It was also found that when clutch specifications and driving conditions were varied, the gradient of the correction also varied, but the correlation remained proportional as long as the same facing material was used. The gradient was ranked as a wear property specific to the facing material.

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.

Effects of various scatter factors on fatigue strength for arc-welds were studied by fatigue test results and sensitivity analysis using the method of cyclic plastic zone size (ω*). The followings were clarified. First, effects of flank angle could be decided by the sensitivity calculated based on the relation between fatigue life for finite life and flank angle. Second, effects of material could be explained by the sensitivity for which the difference of fatigue strength coefficient for each material was analysed. The results, it was verified that there was no effect in notch specimens and there was effect in smooth specimens. Third, effect of thickness was defined by function of the ratio of thickness.

Conventionally, the Ni-based superalloys NCF3015 (30Ni-15Cr) and the high nickel content NCF440 (70Ni-19Cr) (with its outstanding wear resistance and corrosion resistance), have been used as engine exhaust valve materials. In recent years, automobile exhaust gases have become hotter because of exhaust gas regulations and enhanced fuel consumption efficiency. Resource conservation and cost reductions also factor into global environmental challenges. To meet these requirements, NCF5015 (50Ni-15Cr), a new resource-conserving, low-cost Ni-based heat-resistant alloy with similar high-temperature strength and wear resistance as NCF440, has been developed. NCF5015's ability to simultaneously provide wear resistance, corrosion resistance and strength when NCF5015 is used with diesel engines was verified and the material was then used in exhaust valves.

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.

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.

By increasing the percentage of highly dissociative strong acid components included in the neutralizing acid of the electrodeposition coating, it was possible to improve electrical conductivity and coulomb efficiency and achieve excellent throwing power. The GA cratering caused by the increase in the strong acid ratio was resolved by setting the strong acid ratio to 90% while reducing MEQ. By increasing coulomb efficiency, the quantity of hydrogen gas produced during electrodeposition was minimized, and as a result, gas pinholes remaining in the coating were reduced, increasing the smoothness of the coating beyond than that of the current materials. As a result of this study, the usage of e-coating per vehicle body was reduced by approximately 11%.