Takayoshi Yoshioka

Bio: Takayoshi Yoshioka is an academic researcher from Toyota. The author has contributed to research in topics: Exhaust gas recirculation & Diesel fuel. The author has an hindex of 4, co-authored 8 publications receiving 111 citations. Previous affiliations of Takayoshi Yoshioka include Toyota Motor Engineering & Manufacturing North America.

Cylinder wear mechanism in an EGR-equipped diesel engine and wear protection by the engine oil

Abstract: Piston ring moving zone in the cylinder is one of the most critical lubrication regimes in diesel engines. This area is susceptible to combustion substances. In particular, abnormal wear is occasionally detected due to Exhaust Gas Recirculation (EGR) system equipment. In Japan, NO/sub x/ emission requirements for passenger car diesels have become more stringent effective October 1, 1986. OEMs tend to apply EGR systems to reduce NO/sub x/ in exhaust gas. In order to identify the phenomenon of abnormal cylinder wear of EGR equipped engine, engine bench tests were conducted under varied conditions in EGR equipment, cooling water temperature and fuel sulfur content. The test results suggest that wear caused at low temperature is mainly corrosive wear attributable to sulfuric acid formed by reaction with fuel sulfur and condensed water. Engine oil additives behavior against sulfuric acid was studied for control of corrosive wear and excellent CD 10W-30 engine oil was developed by selection of additives from the viewpoint of capability to neutralize sulfuric acid. The developed product demonstrated very good wear protection performance in the bench tests using EGR equipped engines.

Noise and Vibration Reduction Technology in New Generation Hybrid Vehicle Development

Abstract: The new gasoline hybrid car, "the Prius", has achieved both two-liter class power performance and world top-class gas mileage with the new Toyota Hybrid System "THS II". Compared with the previous THS, the electric motor drive power of the THS II has been boosted by 50% and the weight of this system has been reduced by 20%. This paper describes the NV problems caused by the improvements to the hybrid system, and the countermeasures for them. It also describes the technologies for reduction of engine start vibration. Finally an evaluation method and countermeasures against interior engine noise are described.

Cylinder wear mechanism in an EGR-equipped diesel engine and wear protection by the engine oil

Abstract: Piston ring moving zone in the cylinder is one of the most critical lubrication regimes in diesel engines. This area is susceptible to combustion substances. In particular, abnormal wear is occasionally detected due to Exhaust Gas Recirculation (EGR) system equipment. In Japan, NO/sub x/ emission requirements for passenger car diesels have become more stringent effective October 1, 1986. OEMs tend to apply EGR systems to reduce NO/sub x/ in exhaust gas. In order to identify the phenomenon of abnormal cylinder wear of EGR equipped engine, engine bench tests were conducted under varied conditions in EGR equipment, cooling water temperature and fuel sulfur content. The test results suggest that wear caused at low temperature is mainly corrosive wear attributable to sulfuric acid formed by reaction with fuel sulfur and condensed water. Engine oil additives behavior against sulfuric acid was studied for control of corrosive wear and excellent CD 10W-30 engine oil was developed by selection of additives from the viewpoint of capability to neutralize sulfuric acid. The developed product demonstrated very good wear protection performance in the bench tests using EGR equipped engines.

Noise and vibration suppression in hybrid electric vehicles: State of the art and challenges

Abstract: The need for more efficient and renewable means of transport makes the development of hybrid electric vehicles (HEVs) an important topic for both automobile manufacturers and academic researchers. Noise, vibration, and harshness (NVH) of a vehicle are important factors for vehicle users and essential for successful commercialization of this vehicle type. This paper is a compact state-of-the-art review of both NVH characteristics and relevant suppression methods for HEVs. The NVH-related problems are categorized into three categories: engine, powertrain, motor-related. A detailed overview of each category/problem-type is provided, the NVH-suppression methods for different types of HEVs are introduced, and their respective advantages discussed. In addition, emerging developments and ideas for future improvements are summarized. As a result, the paper should be particularly helpful for researchers, who are interested in the development of high-performance HEVs that can provide both substantially improved ride-comfort and reduced energy-consumption.

Development and testing of the torque control for the permanent-magnet synchronous motor

Abstract: Hybrid electrical vehicles and electrical vehicles are being actively developed. A hybrid electric vehicle motor design requires high efficiency, high power/weight ratio, and reliability from low rotor speed to high rotor speed. The permanent-magnet synchronous motor is used in order to fulfill these requirements. The purpose of this paper is to develop a permanent-magnet synchronous motor control method for all rotor speeds. This method increases the torque and the efficiency at high speed when compared to the ordinary current error feedback method. A method composed of two compensators is proposed to achieve this objective. One of the compensators controls the torque using the voltage phases. The other one is the ordinary current error feedback. Several correcting methods for the voltage phase compensator have been proposed for the compensator for many control demands. The validity of the proposed method was confirmed using simulation and experimental evaluations.