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Technical Paper

Effects of Lubricant Composition on Fuel Efficiency in Modern Engines

A bench engine test for evaluating the fuel efficiency of automotive crankcase oils using modern engines was developed. The fuel consumption was primarily proportional to the viscosity of the oils down to 5 mm2/s at operating temperatures, indicating that the use of low-viscosity oil was effective in improving fuel efficiency. This may be because the oil film would be formed easily, since sliding parts, such as valve train systems, in modern engines are finely finished. Organo molybdenum dithiocarbamates were effective in improving fuel efficiency at high temperature. A 2.7% improvement in fuel efficiency relative to conventional SAE 10W-30 oils was achieved by the combination of low-viscosity SAE 5W-20 oils and organo molybdenum dithiocarbamates under constant operating conditions with engine speed 1,500 rpm and torque 37.2 N•m.
Technical Paper

A Newly Developed Intelligent Variable Valve Timing System - Continuously Controlled Cam Phasing as Applied to a New 3 Liter Inline 6 Engine

To meet the requirements for higher horsepower and torque as well as lower fuel consumption and emissions, we have developed a new “Intelligent Variable Valve Timing (VV-i)” system. It gives continuously variable intake cam phasing by up to 60 degrees crank angle (CA) . This system not only increases WOT output by optimizing intake valve closing timing but also reduces fuel consumption and NOx/ HC emissions under part load by increasing intake and exhaust valve overlap on 4 stroke Spark Ignited engines. VVT-i has been applied to optimize a new 3-liter inline 6 engine for higher torque and at the same time better fuel economy with continuous and wide-range cam phasing.
Technical Paper

Development of Titanium Nitride Coated Shim for a Direct Acting OHC Engine

In order to meet requirements for lower fuel consumption, we have developed a technique for significantly decreasing valve train friction for a direct acting OHC engine. Droplets of pure titanium generated by the titanium nitride coating process of the shims improves the surface roughness of the cams, which eliminates the need to polish the cams. In an engine with these shims, the surface roughness of the cams is considerably improved within a few minutes of initial operation by the polishing action of the droplets. Valve train friction is greatly reduced by improving the surface roughness of the cams and shims, which results in better fuel economy.
Technical Paper

Toyota New Compact Five-Speed Automatic Transmission for RWD Passenger Cars

A new compact five-speed automatic transmission (A650E) has been developed for front engine rear wheel drive cars. The development of this transmission has been aimed at improving fuel consumption, power performance, engine noise reduction during highway cruising and smooth acceleration by employing a wide range of gearing and close gear ratios. Generally a five-speed automatic transmission is larger than a four-speed, because of additional friction elements and gears. This can result in a change in the floor panel of the car body. However, by removing a one-way clutch for second gear and employing a unique gear-train layout, this transmission has the same circumference and length as the conventional four-speed automatic transmission (A340E)(1).1 In order to reduce first or second gear noise, gear specification and supporting structures of planetary gears have been optimized by FEM analysis.
Technical Paper

Effect of Mirror-Finished Combustion Chamber on Heat Loss

The use of ceramic insulation to reduce engine heat loss and thus improve fuel economy was examined but found to be detrimental rather than advantageous. This paper analyzes the reasons and presents an alternative approach, namely minimizing the heat transfer area. Experiments were conducted to determine the effects of surface smoothness on BSFC, output torque, heat release rate and piston temperature. It was found that with a mirror-finished combustion chamber, heat loss is decreased and consequently engine output is raised, while fuel consumption is lowered. The percentage reduction in heat loss was ascertained by numerically simulating combustion and was confirmed by FEM analysis of piston thermal distribution.
Technical Paper

Key Factors of Fuel Injection System to Draw Out Good Response in 4-Valve Engine

Fuel and air behavior in the induction passage of a 4-valve engine were investigated in order to improve response at low and medium engine speeds. It was found that response is affected not only by wall vetting but also by fuel being pushed back into the intake manifold and by a lack of fuel which occurs during the transient. Futhermore, fuel-air mixing was found to be insufficient at certain injection timings, resulting in poor combustion and a consequent increase in exhaust emission and fuel consumption. This paper describes the factors of the fuel injection system which are critical for optimum response. Recommendations are made for injector location and injection timing and a proposal is put forward for a system of compensatory fuel injection to improve combustion efficiency during acceleration.
Technical Paper

New Four Valves Per Cylinder Basic Engine for Passenger Car

Through the experience in developing several 4-valve sporty engines, we have had an idea that 4-valve technology regarded as one of sporty engines may be applied to a standard engine of a passenger car. Making use of the superior characteristics of 4-valve technology, combustion chamber design and valve train system were completely refined for a standard engine. Higher torque in low to middle speed range and good fuel economy, important features in practical use, were pursued as the prior target of development. As a passenger car engine, comfortable sound in passenger compartment is an important feature as well as high performance and good fuel economy. With these concepts, we have developed the 3S-FE, 2-liter, 4-valve engine which has achieved 5.1& torque, 18.6% horse power and 9.7% Fuel consumption (highway mode) gains compared with the original 2S-E, 2-liter, 2-valve engine.
Technical Paper

Development of Propeller Shaft with a New Nylon Coating

In the present social environment, automobile demands further reduction of fuel consumption and light weight. Now that the reduction of vehicle weight is being pursued, even a slight looseness in each element of an automobile may become a source of vibration and noise due to the lowered rigidity of such an automobile. The quietness of vehicles is urged, spline backlash in the spline mechanism exhibits a problem in some cases. A propeller shaft, a part of the automobile driving system, also has a sliding spline mechanism as shown in Fig. 1. Such a propeller shaft is required to have functions of transmitting high torque driving forces, and absorbing the variation of the vehicle driveline overall length at the same time. Vibration and noise are apt to occur if when torque is applied, there is a significant balance fluctuation or great sliding resistance due to spline backlash.
Technical Paper

The New Toyota Inline 4-Cylinder 2.5L Gasoline Engine

In order to adapt to energy security and the changes of global-scale environment, further improvement of fuel economy and adaptation to each country’s severer exhaust gas emission regulation are required in an automotive engine. To achieve higher power performance with lower fuel consumption, the engine’s basic internal design such as an engine block and cylinder head were changed and the combustion speed was dramatically increased. Consequently, stroke-bore ratio and valve layout were optimized. Also, both flow coefficient and intake tumble ratio port were improved by adopting a laser cladded valve seat. In addition, several new technologies were adopted. The Atkinson cycle using a new Electrical VVT (Variable Valve Timing) and new combustion technology adopting new multi-hole type Direct fuel Injector (DI) improved engine power and fuel economy and reduced exhaust emissions.
Technical Paper

High Efficiency Supercharger Increases Engine Output, Reduces Fuel Consumption Through Computer Control

Efficiency of a supercharger mainly depends on the clearances between the rotors and the housing, but it has hitherto proved impossible to reduce the clearances without a strong possibility of seizure. A two lobe Roots type supercharger has been developed which overcomes this problem by means of a special resin coating on the rotors. As a result, an increase of 18% in volumetric efficiency of the supercharger is achieved. Engine torque is increased by 30%. Drive power loss resulting from the operation of a supercharger at partial load when boost was not required caused fuel consumption to increase by about 10%. An electro magnetic clutch and an air by-pass valve controlled by the onboard computer were used in the new supercharger to eliminate this fuel economy loss. A passenger car equipped with the new supercharged 2-liter engine demonstrated about the same acceleration performance as a 3-liter class car without sacrificing fuel economy.
Technical Paper

New TOYOTA 4.8L V10 Petrol High Performance Engine for Lexus LFA

Achieving the speed and performance of a true supercar was merely the starting point of this development. In addition, the development also focused on achieving emotive performance attributes to enhance driver appeal. For this the engine was developed to assist a vehicle handling provides unsurpassed response, the creating a feeling of infinite acceleration potential, response is instantaneous and based on close understanding of driver's reactions and Awe inspiring sound is providing. It meets the latest emission standard Euro V and achieves good fuel consumption with a wide range stoechiometric air fuel ratio, till speeds up to 240km/h.
Technical Paper

Impact Study of High Biodiesel Blends on Exhaust Emissions to Advanced Aftertreatment Systems

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. In the impact on exhaust emissions, the impact of high biodiesel blends into diesel fuel on diesel emissions was evaluated. The wide variety of biodiesel blendstock, which included not only some kinds of fatty acid methyl esters(FAME) but also hydrofined biodiesel(HBD) and Fischer-Tropsch diesel fuel(FTD), were selected to evaluate. The main blend level evaluated was 5, 10 and 20% and the higher blend level over 20% was also evaluated in some tests. The main advanced technologies for exhaust aftertreatment systems were diesel particulate filter(DPF), Urea selective catalytic reduction (Urea-SCR) and the combination of DPF and NOx storage reduction catalyst(NSR).
Technical Paper

The Humidity Control System Applied to Reduce Ventilation Heat Loss of HVAC Systems

Vehicles have been more required to save energy against the background of the tendency of ecology. As the result of improving efficiency of internal combustion engines and adoption of electric power train, heat loss from engine coolant, which is used to heat the cabin, decreases and consequently additional energy may be consumed to maintain thermal comfort in the passenger compartment in winter. This paper is concerned with the humidity control system that realizes reduction of ventilation heat loss by controlling recirculation rate of the HVAC system by using highly accurate humidity sensor to evaluate risk of fogging on the windshield. As the results of the control, fuel consumption of hybrid vehicles decreases and maximum range of electric vehicles increases.
Technical Paper

Development of New Hybrid System for Compact Class Vehicles

Toyota has been evolving a hybrid system since introducing the first mass-production hybrid vehicle in 1997 in response to the increasing automotive-related issues of CO2 emissions, energy security, and urban air pollution. This paper describes a newly developed hybrid system design and its performance. This system was developed with the main purpose to improve fuel consumption, especially for better real world fuel consumption; and to enhance its compatibility with multiple vehicle adoption by downsizing and reducing the weight of its components. At the same time, the hybrid system achieved improved power performance while satisfying stringent emission regulations in the world.
Technical Paper

The application of VHDL-AMS multi-domain HV simulation to the power performance and the fuel economy during warming up process

In order to reduce CO2, EV and Hybrid Vehicle (HV) are effective. Those type vehicles have different power train from conventional vehicle. Those new power trains drastically improve their efficiency from conventional vehicle with keeping same or superior power performance. On the other hand, those vehicles have the issue for thermal energy shortage during warming up process. The thermal energy is very large. The thermal energy seriously affect on the fuel economy for HV and the mileage for EV. In this paper, the power performance, the fuel economy and the effect of heat energy recovery from the exhaust gas are discussed for HV. For the power performance, the simulated acceleration time of 0-100km/h was 11.8sec and the measured vehicle time was 11.9sec. The error between simulation and actual measurement result was 1.2%. As for the fuel economy, the energy management using exhaust gas heat exchange system improved 10.3% of the fuel consumption during warming up.
Technical Paper

Economy with Superior Thermal Efficient Combustion (ESTEC)

From the time the first Hybrid Vehicle (HV) was launched, 17 years have past, and HV vehicles have boosted the global CO2 reduction trend. In order to maximize their merit, many HV engines focused on the best fuel consumption value namely thermal efficiency. This was because HV systems can control the operating area of engine and get merit. However, considering climate change and energy issues, it is important to focus conventional vehicle as well as HV vehicle progress. The Atkinson cycle with a high compression ratio is the typical approach that HV engines use to enhance thermal efficiency. However, the drawback of the high compression ratio is a reduction of engine torque. Thermal efficiency at low load areas is relatively more important with conventional engines than with HV engines and how to overcome these issues is significantly important with conventional engines.
Technical Paper

Study of Ignition System for Demand Voltage Reduction

Improving the engine efficiency to respond to climate change and energy security issues is strongly required. In order to improve the engine efficiency, lower fuel consumption, and enhance engine performance, OEMs have been developing high compression ratio engines and downsized turbocharged engines. However, higher compression ratio and turbocharging cause cylinder pressure to increase, which in turn increases the demand voltage for ignition. To reduce the demand voltage, a new ignition system is developed that uses a high voltage Zener diode to maintain a constant output voltage. Maintaining a constant voltage higher than the static breakdown voltage helps limit the amount of overshoot produced during the spark event. This allows discharge to occur at a lower demand voltage than with conventional spark ignition systems. The results show that the maximum reduction in demand voltage is 3.5 kV when the engine is operated at 2800 rpm and 2.6 MPa break mean effective pressure.
Technical Paper

Power Plant Model of Fuel Consumption and Vibration for Vehicle Concept Planning

It is important for vehicle concept planning to estimate fuel economy and the influence of vehicle vibration in advance. This can be accomplished using virtual engine specifications and a virtual vehicle frame. In this paper, I will show the power plant model with electric starter and battery that can predict fuel economy, combustion heat results and transient torque. The power plant is a 1.3L 4cyl designed for NA Spark Ignition. The power plant model was realized using an energy based model using VHDL-AMS. Here, VHDL-AMS is modeling language stored in IEC international standard (IEC61691-6) and can realize multi physics in 1D simulation. The modeling language supports electrical, magnetic, thermal, mechanical, fluidic and compressive fluidic domains. The model was created in house using VHDL-AMS and validated on ANSYS SIMPLORER. The simulated results of fuel energy consumption agreed with driving energy and amount of energy losses, e.g. cooling loss, exhaust loss.
Technical Paper

Friction Reduction Effect of the New Concept Bearing with Partial Twin Grooves in Cold Condition

Engine friction reduction is an effective means to improve fuel consumption. Fluid friction reduction of main bearing is examined for engine friction reduction in cold condition. As one of the examinations, it was focused on low temperature of lubricating oil in the early stage during engine cold start. In hydrodynamic lubrication, the oil film temperature is maintained by balance between heat generation and heat transfer. The heat generation is generated by shear of lubricating oil. The factors of the heat transfer, the following elements are considered as follows, A) The heat transfer to a crank shaft, B) The heat transfer to a bearing, C) The heat transfer by convection. If the heat generation is constant, oil film temperature is increased by reduction of heat transfer. It is considered that the reduction of oil leakage and reduction of the heat transfer by convection is equivalent.
Technical Paper

Development of New Continuously Variable Transmission for 2.0-Liter Class Vehicles

In response to increasing demands for measures to conserve the global environment and the introduction of more stringent CO2 emissions regulations around the world, the automotive industry is placing greater focus on reducing levels of CO2 through the development of fuel-efficient technologies. With the aim of improving fuel economy, a new continuously variable transmission (CVT) has been developed for 2.0-liter class vehicles. This new CVT features various technologies for improving fuel economy including a coaxial 2-discharge port oil pump system, wider ratio coverage, low-viscosity CVT fluid, and a flex start system. This CVT is also compatible with a stop and start (S&S) system that reduces fuel consumption by shutting off the engine while the vehicle is stopped. In addition, the development of the CVT improves driveability by setting both the driving force and engine speed independently.