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A new wind tunnel was developed and adopted by Toyota Motor Corporation in March 2013. This wind tunnel is equipped with a 5-belt rolling road system with a platform balance that enables the flow simulation under the floor and around the tires in on-road conditions. It also minimizes the characteristic pulsation that occurs in wind tunnels to enable the evaluation of unsteady aerodynamic performance aspects. This paper describes the technology developed for this new wind tunnel and its performance verification results. In addition, after verifying the stand-alone performance of the wind tunnel, a vehicle was placed in the tunnel to verify the utility of the wind tunnel performance. Tests simulated flow fields around the vehicle in on-road conditions and confirmed that the wind tunnel is capable of evaluating unsteady flows.

It is well understood that using lower viscosity engine oils can greatly improve fuel economy [1, 2, 3, 4]. However, it has been impossible to evaluate ultra-low viscosity engine oils (SAE 0W-12 and below) utilizing existing fuel economy test methods. As such, there is no specification for ultra-low viscosity gasoline engine oils [5]. We therefore developed firing and motored fuel economy test methods for ultra-low viscosity oils using engines from Japanese automakers [6, 7, 8]. This was done under the auspices of the JASO Next Generation Engine Oil Task Force (“TF” below), which consists mainly of Japanese automakers and entities working in the petroleum industry. Moreover, the TF used these test methods to develop the JASO GLV-1 specification for next-generation ultra-low viscosity automotive gasoline engine oils such as SAE 0W-8 and 0W-12. In developing the JASO GLV-1 specification, Japanese fuel economy tests and the ILSAC engine tests for evaluating engine reliability were used.

The effects of an increasing boost pressure, a high EGR rate and a high injection pressure on exhaust emissions from an HSDI (High Speed Direct Injection) diesel engine were examined. The mechanisms were then investigated with both in-cylinder observations and 3DCFD coupled with ϕT-map analysis. Under a high-load condition, increasing the charging efficiency combined with a high injection pressure and a high EGR rate is an effective way to reduce NOx and soot simultaneously, which realized an ultra low NOx of 16ppm at 1.7MPa of IMEP (Indicated Mean Effective Pressure). The flame temperature with low NOx and low soot emissions is decreased by 260K from that with conventional emissions. Also, the distribution of the fuel-air mixture plot on a ϕT-map is moved away from the NOx and soot formation peninsula, compared to the conventional emissions case.

In this study, we combined a diesel engine with the Toyota Hybrid System (THS). Utilizing the functions of the THS, reducing engine friction, lowering the compression ratio, and adopting a low pressure loop exhaust gas recirculation system (LPL-EGR) were examined to achieve both low fuel consumption and low nitrogen oxides (NOx) emissions over a wide operating range. After applying this system to a test vehicle it was verified that the fuel economy greatly surpassed that of a conventional diesel engine vehicle and that NOx emissions could be reduced below the value specified in the Euro 6 regulations without DeNOx catalysts.

A new automatic transmission, engineered from concept for “intelligent” and “anti-aging” (long life), has been designed and developed for TOYOTA's luxury passenger car, LEXUS LS400. This system, which has resulted in silky-smooth shift quality without changes in the long term, is composed of a transmission computer that interacts with engine computer, a number of sensors, an electronically controlled hydraulic unit with linear solenoid valves and assorted devices. As new control logic being developed with the aid of computer simulation to achieve distinction, the hydraulic and engine controls are combined in this system. There is a “feedback control”, where the clutch pressure is controlled according to the rate of acceleration and compensated for dispersion to applied pressure, engine torque and/or the coefficient of dynamic friction of clutches, and at the same time engine torque is reduced by retarding ignition timing.

A communication system that uses roadside beacons to broadcast road and traffic information and private messages to vehicles has been developed. The system, called Road/Automobile Communication System (RACS), was the result of a joint research project involving the Public Works Research Institute and 25 private-sector corporations. This paper contains an outline of RACS and of an onboard system developed by TOYOTA and presents the results of field tests conducted in the Tokyo area. The results not only verify the capability of the RACS system and the effectiveness of the in-vehicle equipment but also indicate the potential of such a beacon based network to improve traffic jam and driving safety whilst providing enhanced communication facilities without increasing radio-wave congestion.

In Biodiesel Fuel Research Working Group(WG) of Japan Auto-Oil Program(JATOP), some impacts of high biodiesel blends have been investigated from the viewpoints of fuel properties, stability, emissions, exhaust aftertreatment systems, cold driveability, mixing in engine oils, durability/reliability and so on. This report is designed to determine how high biodiesel blends affect oil quality through testing on 2005 regulations engines with DPFs. When blends of 10-20% rapeseed methyl ester (RME) with diesel fuel are employed with 10W-30 engine oil, the oil change interval is reduced to about a half due to a drop in oil pressure. The oil pressure drop occurs because of the reduced kinematic viscosity of engine oil, which resulting from dilution of poorly evaporated RME with engine oil and its accumulation, however, leading to increased wear of piston top rings and cylinder liners.

An on-board particulate matter (PM) sensor, consisting of a gas-permeable electrochemical cell with a porous yttria-stabilized zirconia solid oxide electrolyte, was developed to assist the on-board diagnostics (OBD) system of a vehicle. Exhaust is pumped from the anode side to the cathode side and PM deposited on the anode is instantly oxidized by the catalytic effects of the metal component of the electrode at temperatures higher than 350°C. The PM oxidation reaction occurs at the three-phase boundary between the anode, electrolyte and gas phase, and causes a slight change in the bulk average oxygen concentration, which produces electrochemical polarization by the difference in oxygen partial pressures between the anode and cathode. The developed PM sensor has a detection limit of 2 mg/m₃, at which level will enable PM detection in the OBD system according to the EURO VI regulation.

The stability of Diesel/Biodiesel blends can play an important role in deposits formation inside the fuel injection system (FIS). The impact of the stability of FAME/Diesel fuel blends on lacquer deposits formation and on the behavior and reliability of the FIS was investigated using blends of Rapeseed and Soybean methyl esters (RME, SME) and conventional Diesel fuel (volume fractions of RME and SME range from 0 to 20%v/v). Fuels were aged under accelerated conditions and tested on an injection test rig according to an operating cycle developed to provoke injector needle blocking. The soaking duration was found to affect injector fouling. A relationship between the injector fouling tendency and the fuel stability was established. Under current test condition, injectors fouling increased with fuel oxidation measured with Total-Acid-Number.

In order to investigate the effect of sulfur and distillation properties on exhaust emissions, emission tests were carried out using a California Low Emission Vehicle (LEV) in accordance with the 1975 Federal Test Procedure ('75 FTP). To study the fuel effect on the exhaust emissions from different systems, these test results were compared with the results obtained from our previous studies using a 92MY vehicle for California Tier 1 standards and a 94MY vehicle for California TLEV standards. (1)(2) First, the sulfur effect on three regulated exhaust emissions (HC, CO and NOx) was studied. As fuel sulfur was changed from 30 to 300 ppm, the exhaust emissions from the LEV increased about 20% in NMHC, 17% in CO and 46% in NOx. To investigate the recovery of the sulfur effect, the test fuel was changed to 30 ppm sulfur after the 300 ppm sulfur tests. The emission level did not recover to that of the initial 30 ppm sulfur during three repeats of the FTP.

Detergent additives in automotive gasoline fuel are mainly designed to reduce deposit formation on intake valves and fuel injectors, but it has been reported that some additives may contribute to CCD formation. Therefore, a standardized bench engine test method for CCDs needs to be developed in response to industry demands. Cooperative research between the Petroleum Association of Japan (PAJ) and the Japan Automobile Manufacturers Association, Inc. (JAMA), has led to the development of a 2.2L Honda engine dynamometer-based CCD test procedure to evaluate CCDs from fuel additives. Ten automobile manufacturers, nine petroleum companies and the Petroleum Energy Center joined the project, which underwent PAJ-JAMA round robin testing. This paper describes the CCD test development activities, which include the selection of an engine and the determination of the optimum test conditions and other test criteria.

A new test machine has been developed which can evaluate vibration due to stick-slip using an actual full-scale clutch pack. Using this machine, a static breakaway friction coefficient measurement test method and a stick-slip test method have been established. Both methods have been shown to provide results which correlate with the results from both a full-scale assembly test and a vehicle shudder evaluation test. The evaluation of the frictional properties of commercial oils using these test methods showed that the static breakaway friction coefficient and the stick-slip properties have generally contradictory performance to each other for automatic transmission. The study of the frictional properties for typical additives and an analysis of the surface of the steel plates with ESCA (Electron Spectroscopy for Chemical Analysis) showed that the frictional properties are significantly affected by the additives adsorbed on the clutch plate sliding surface.

Recently in the world, many modifications and improvements have been taking place in automatic transmission fluid (ATF) in order to get more excellent performance and durability of automatic transmission. The most important criterion for the improvement of ATF is a superior friction characteristic. To consider the performance of ATF, we have investigated the correlation of criteria between actual vehicle tests and bench-scale tests (e.g. SAE#2 Friction Test). And it was proved that conventional criteria and test methods for bench-scale tests were not enough to give best prediction of actual vehicle performance especially for shift quality, anti-shudder performance and static torque capacity which were regarded as of major importance for the development. Based on the findings, we have considered new criteria and test methods for the frictional characteristics, and specific requirements for ATF have been proposed from the standpoint of actual vehicle performance.

In order to clarify the diesel fuel spray characteristics inside the cylinder, we developed two novel techniques, which are preparation of same level of temperature and pressure ambient as inside cylinder and quantitative measurement of vapor concentration. The first one utilizes combustion-type constant-volume chamber (inner volume 110cc), which allows 5 MPa and 873K by igniting the pre-mixture (n-pentane and air) with two spark plugs. In the second technique, TMPD vapor concentration is measured by using Laser Induced Exciplex Fluorescence method (LIEF). The concentration is compensated by investigation of the influence of ambient pressure (from 3 to 5 MPa) and temperature (from 550 to 900 K) on TMPD fluorescence intensity. By using two techniques, we investigated the influence of nozzle hole diameter, injection pressure and ambient condition on spray characteristics.

A full vehicle multi-body dynamic (MBD) model with suspension control system is developed for fatigue life prediction under rough road condition. The model consists of tires, a trimmed body, heavy attached parts, powertrain, suspension, joints, and a driver model, and includes a suspension control system that varies characteristics of the suspension according to the rough road inputs. For tires, a commercial MBD tire model is employed with identifiable parameters. The models are simulated to run on the optically measured road surface of the proving ground. Apart from the trimmed body, several important heavy attached parts are modeled separately, that represent dynamic behavior that induces complex body input load. These parts, along with suspension and powertrain systems are connected to the body using nonlinear elements such as joints, springs, and dampers. Contact conditions are used to represent mount bushing, hood lock, stopper rubber, etc.

Technologies of 4WD chassis dynamometers (CHDY hereinafter) have advanced dramatically over the past several years, enabling 4WD vehicles to be tested without modifying their drive-train into 2WD. These advances have opened the use of 4WD-CHDY in all fuel economy and emission evaluation tests. In this paper, factors that influence the accuracy of fuel economy tests on 4WD CHDY are discussed. Fuel economy tests were conducted on 4WD CHDY and we found that most of the vehicle mechanical loss is the tire loss and that stabilizing the tire loss of the test vehicle is essential for the test reproducibility.

Under high-pressure conditions such as those existing in a common-rail system, a serious concern is the possibility of wax precipitation from diesel fuels and the consequent deterioration in the diesel engine performance, even if the temperature is higher than the CP (cloud point) of the fuel. By using a diesel engine with a common-rail system, high-acceleration tests were performed under high-load conditions for three test fuels, which correspond to Japanese JIS grade 2 diesel fuels but have different cold-temperature properties, at a temperature exceeding their CPs. The test revealed differences in the engine speed and the throttle position among the test fuels. It was suggested that there was a possibility of a fault in fuel injection caused by the wax precipitation at high pressure.

A description is made of new control methods to improve response of wheel slip regulation. These methods enabled a new Traction Control (TRC) system based on throttle control rather than brake pressure to be developed. Major points are as follows: (1) Use of fuel injection cut-off to minimize delay (2) Additional adaptive throttle control logic By these means, a response nearly equal to that with brake pressure control is achieved at lower cost and with a considerable weight saving. Furthermore, the system, by suppressing noise and vibration, enhances the driver's control ability.

EXPERIMENTAL ANALYSIS for the increase of the radiator cooling air has been performed with special attention to the utilization of air pressure in high-speed running conditions. Measurements of pressure distributions at the radiator cooling air intake showed that the prevention of the occurrence of separations around the bumper is the efficient method to increase the cooling air. Furthermore, the optimum configuration for the radiator cooling air discharge has also been experimentally studied using a simplified model which simulates the under part of the engine compartment. These improvements made the vehicle radiator cooling air volume increase 14% under high-speed running conditions.

This paper analyzes the vibration of open-top cars known as lateral shake. The characteristics of the phenomenon were identified by means of road tests and a test method called the shake test was devised to reproduce these characteristics in order that the respective roles of the suspension, body and engine could be determined. On the basis of the analysis findings, a simple but practical simulation model was realized and used to investigate various methods of reducing lateral shake. The simulations indicated that although changing the natural frequency of the suspension has little effect, increasing the natural torsional frequency of the body and/or utilizing the engine as a dynamic damper results in a significant improvement. Further experiments conclusively demonstrated that by optimizing the body structure in accordance with FEM analysis results and optimizing the spring constant of the engine mounts, the level of lateral shake can be halved.