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Exhaust emissions from a vehicle under road driving condition is affected by the control state of ECU (Engine Control Unit). This control state highly depends on the driving force of the vehicle. The driving force is nearly equal to the driving resistance, which is the sum of the acceleration resistance, the air resistance, the rolling resistance and the gradient resistance. Although it is essential to take an accurate measurement of the road gradient, it is quite difficult to evaluate the gradient resistance in testing on-road driving. In this study, the measurement methods of the road gradient and the altitude with GPS, gyro sensor and height sensor are reported. The road gradient under the on-road driving condition is evaluated by the combination of measuring the pitch angle with the gyro sensor and measuring the vehicle gradient with the two height sensors. Verifying of this method, the altitude of the driving test route is also evaluated.

For the evaluation of environment load from vehicles under road driving condition, on-board measurement system with the ability to measure emission concentration, engine conditions and vehicle conditions is necessary. These days, with the advancement of measurement technology, on-board exhaust gas analyzers have been developed, and it is now possible to measure the volume emission of exhaust gas using these analyzers. However, it is important to evaluate the mass emission from vehicles. For the conversion from the volume emission to the mass emission, the value of exhaust flow rate is required. However, the measurement method of exhaust flow rate with high accuracy has not been established. In this study, the measurement method of exhaust gas flow rate, the Map Method, was investigated for gasoline vehicles.

The object of this study is to investigate an on-board diagnostic method to detect the deterioration of a three-way catalyst (TWC) under actual vehicle operating conditions, including the acceleration state. The signal data of two oxygen sensors were processed by the fast Fourier transformation (FFT) method. As a result, we found that the power spectrum of the signal waves can be the index of catalyst deterioration degree. Furthermore, it was confirmed that the difference between the power spectrum of the upstream oxygen sensor signal and one of the downstream oxygen sensor signal named ΔPower is effective index for detection of deteriorated catalyst under acceleration conditions.

Compared with petroleum fuel, liquefied petroleum gas (LPG) demonstrates advantages in low CO2 emission because of propane and butane, which are the main components of LPG, making H/C ratio higher. In addition, LPG is suitable for high efficient operation of a spark ignition (SI) engine due to its higher research octane number (RON). Because of these advantages, that is, diversity of energy source and reduction of CO2, in the past several years, LPG vehicles have widely used as the alternate to gasoline vehicles all over the world. Consequently, it is absolutely essential for the performance increase of LPG vehicles to comprehend the combustion characteristics of LPG and to obtain the guideline for engine design and calibration. In this study, an LPG-SI engine was built up by converting fuel supply system of an in-line 4-cylinder gasoline engine, which has 1997 cm3 displacement with MPI system, to LPG liquid fuel injection system [1].

The effects of engine and after-treatment control conditions on emissions fluctuation were evaluated and the technical idea for improving the repeatability in tailpipe emission measurement from DISI vehicles was provided. To improve measurement repeatability, low emissions analyzers with dilution air refining system were employed for this research. In addition, a new device that enabled monitoring of signals from the Engine Control Unit (ECU) was developed. A novel approach using these devices was applied to DISI gasoline engine vehicles equipped with de-NOx catalyst to clarify emission characteristics in the Japanese 10.15 test cycle emission tests. Through the tests, it is found that NOx emissions most correlated with the temperature at the de-NOx catalyst. CO and HC reaching the de-NOx catalyst played an important role in the temperature increase of de-NOx catalyst by exothermic reactions.

This paper proposes and evaluates methods for measuring the driving capability of a robotic driver for automotive emissions testing. In order to evaluate driving capabilities, variables such as actual speed, intake manifold pressure, accelerator pedal position, brake pedal position, and others are measured while the driver repeats a specific speed pattern. The values of the data between successive runs are statically analyzed to determine what is referred to as the residual deviation. The residual deviation is then used as an “index of repeatability” to evaluate the repeatability of emissions tests results. Additionally, the relationship between target speed and actual speed among runs is evaluated using similar techniques to generate an “index of traceability.” Tests were run on several drivers.

Exhaust emissions behavior from a vehicle under road driving condition is affected by a driving force of a vehicle. It is impossible to measure the driving force by an existing torque meter under this on-road driving condition. This study reports the development and verification of the wheel torque meter which is possible to measure driving force under the on-road driving condition and has enough strength and accuracy. The wheel torque meter developed in this study consists of a torque detector with a strain gauge type torque transducer, a telemeter receiver and a data logger. The strain gauge type torque transducer is equipped between hub and wheel at the drive axle tire, because of the narrow width of this transducer, and it is possible to be placed against vehicle without significant conversion of the vehicle. Because of these characters, this transducer is possible to be used for an on-road driving vehicle.