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Technical Paper

Development of the New THS-II Powertrain for Compact Vehicles

Reflecting on the world's trend on saving crude oil consumption and to create an economical fuel efficient vehicle for the increasing world population, a new THS-II HV powertrain has been developed for the compact vehicle class. The application of a THS type powertrain for the compact vehicle class was a first for the world and to achieve it, brand new hardware, and software needed to be developed. For the Internal Combustion Engine (ICE), state of the art technologies such as the use of the Atkinson cycle with Variable Valve Timing (VVT), cooled exhaust gas recirculation (EGR), an electric water pump, a compact exhaust manifold, a Low Friction chain, beltless system and exhaust heat recovery system were applied. For the electric motor, copper wire with a rectangular cross section and divided stator cores combined with a newly developed production process were applied for higher volumetric density.
Technical Paper

Development of a New Breath Alcohol Detector without Mouthpiece to Prevent Drunk Driving

Breath alcohol interlock systems are used in Europe and the U.S. for drunk driving offenders, and a certain effect has been revealed in the prevention of drunk driving. Nevertheless, problems remain to be solved with commercialized detectors, i.e., a person taking the breath alcohol test must strongly expire to the alcohol detector through a mouthpiece for every test, more over the determination of the breath alcohol concentration requires more than 5 seconds. The goal of this research is to develop a device that functions suitable and unobtrusive enough as the interlock system. For this purpose, a new alcohol detector, which does not require a long and hard blowing to the detector through a mouthpiece, has been investigated. In this paper, as a tool available on board, a contact free alcohol detector for the prevention of drunk driving has been developed.
Technical Paper

Development of New 1.8-Liter Engine for Hybrid Vehicles

In recent years, attention has been focused on a hybrid vehicle capable of substantial reductions in CO2 exhaust emissions. This paper describes the newly developed 1.8-liter 2ZR-FXE gasoline engine for use with a hybrid system for compact vehicles, which effectively combines higher driving performance with higher fuel efficiency. This engine was based on the 1.8-liter 2ZR-FE engine with outstanding performance and fuel efficiency. This engine has achieved high thermal efficiency by using the high-expansion ratio cycle “Atkinson cycle”, as with the previous 1NZ-FXE engine. Additionally, a new cooled Exhaust Gas Recirculation (EGR) system and electric water pump were adopted to further improve fuel efficiency. A high efficiency cooler was used to cool the EGR gas, which enabled the introduction of the EGR gas at high load conditions, and exhaust gas temperature was reduced.
Technical Paper

Water Jacket Spacer for Improvement of Cylinder Bore Temperature Distribution

For reduction of fuel consumption, a new device “Water Jacket Spacer” which improves temperature distribution of a cylinder block bore wall was developed. In the case of a conventional cylinder block, coolant flow concentrates at the bottom and middle region of the water jacket. While temperature of the upper bore wall is high (due to high-temperature combustion gas) the temperature of the lower bore wall is low, since its only function is to support the piston. When the developed spacer is inserted into a water jacket, the coolant flow concentrates at the upper part of the jacket. As a result, cooling ability to the upper bore wall was improved and temperature of lower bore wall was increased, thereby reducing fuel consumption.
Technical Paper

Modeling of Wall Impinging Behavior with a Fan Shaped Spray

The experiment-based droplet impinging breakup model was applied to a fan shaped spray and the impinging behavior was analyzed quantitatively. Evaluation of the quantitative results with validation tests verified the following. The model enables prediction of fan shaped spray thickness after impingement caused by the breakup of fuel droplets, which could not be represented with the Wall-Jet model, widely used at present. Fuel film movement on a wall is negligible when the injection pressure of the fan shaped spray is high and the spray travelling length is not too short. The proposed heat transfer coefficient between fuel film and the wall is too small to represent the vaporizing rate of the fuel film.
Technical Paper

A Study of Anticorrosive Technology in Super Long Life Coolant

The protection of the environment has become a worldwide concern. To reduce the effects of engine coolant on the environment, ways to minimize the amount of coolant released into the environment were investigated. One option is to develop a super long-life coolant. The key issue in developing a long-life engine coolant is selecting an appropriate inhibitor. The inhibitor should be stable over time and completely anticorrosive. In general carboxylic acids are considered to be the class of inhibitors with the highest stability. However, various lab studies have shown the long-term use of monocarboxylic acid could form the foreign substance that causes blockage in radiators. Therefore, the mechanism leading to the formation of foreign substance was determined. A series of carboxylic acids and additives were evaluated. An optimum formulation was then determined, resulting in the development of the Super Long Life Coolant.
Journal Article

Development of Paint Booth: “New Paint Mist Collection Method”

1 Inside a paint booth to spray paint on vehicle bodies, bumpers, and other parts (hereinafter referred to as “works”), air whose temperature and humidity are controlled by air-conditioner is supplied by blower fans through filters. Dust-eliminated and regulated air flow is sent downward from top to bottom (hereinafter referred to as “downflow”) in the painting booth. Conventionally, paint which does not adhere to work in spraying (hereinafter referred to as “paint mist”) is collected while flowing at a high speed through a slit opening called venturi scrubber in a mixture of air and water. However, this mist collecting system using venturi scrubber requires a large space with a large amount of pressure loss while consuming substantial energy. By radically changing the mist collecting principle, we developed a new compact system with less pressure loss aiming to reduce energy consumption by 40% in a half-size booth.
Technical Paper

Development of a Compact Adsorption Heat Pump System for Automotive Air Conditioning System

In order to reduce the energy consumption of the automotive air conditioning system, adsorption heat pump (AHP) system is one of the key technologies. We have been developing compact AHP system utilizing the exhaust heat from the engine coolant system (80-100 °C), which can meet the requirements in the automotive application. However, AHP systems have not been practically used in automotive applications because of its low volumetric power density of the adsorber. The volumetric power density of the adsorber is proportional to sorption rate, packing density and latent heat. In general, the sorption rate is determined by mass transfer resistance in primary particle of an adsorbent and heat and mass transfer resistance in packed bed. In order to improve the volumetric power density of the adsorber, it is necessary to increase the production of the sorption rate and the packing density.
Technical Paper

Efficiency Improvement in Exhaust Heat Recirculation System

In order to speed up engine coolant warm-up, the exhaust heat recirculation system collects and reuses the heat from exhaust gases by utilizing the heat exchanger. The conventional system improves actual fuel economy at the scene of the engine restart in winter season only. The heat recirculation system becomes more effective at the low outside temperature because it takes longer time to warm up engine coolant. However, the heat recirculation system becomes less effective at the high outside temperature because it takes shorter time to warm up engine coolant. Therefore, the new exhaust heat recirculation system is developed, which adopted as follows: 1) a fin-type heat exchanger in order to enhance exhaust recirculation efficiency 2) a thinner heat exchanger component and smaller amount of engine coolant capacity in the heat exchanger in order to reduce the heat mass As a result, the actual fuel economy is more improved in winter season.
Technical Paper

Thermal Management of a Hybrid Vehicle Using a Heat Pump

This paper presents the thermal management of a hybrid vehicle (HV) using a heat pump system in cold weather. One advantage of an HV is the high efficiency of the vehicle system provided by the coupling and optimal control of an electric motor and an engine. However, in a conventional HV, fuel economy degradation is observed in cold weather because delivering heat to the passenger cabin using the engine results in a reduced efficiency of the vehicle system. In this study, a heat pump, combined with an engine, was used for thermal management to decrease fuel economy degradation. The heat pump is equipped with an electrically driven compressor that pumps ambient heat into a water-cooled condenser. The heat generated by the engine and the heat pump is delivered to the engine and the passenger cabin because the engine needs to warm up quickly to reduce emissions and the cabin needs heat to provide thermal comfort.
Journal Article

Development of Motor Cooling Technology in Hybrid Vehicles

1 In order to reduce the size and weight of the hybrid motor, improving motor cooling performance is essential. Therefore, we have been working on the development. This paper will explain the development of cooling technology TOYOTA has been working on, specifically the evolution of the hybrid motor cooling system and structure from the 1st generation Prius to the current model.