Daihatsu, the minivehicle specialist in the Toyota Group, has developed “e:S Technology (Energy Saving Technology) that it says will be at the heart of production of future motor vehicles with high fuel efficiency, low prices, and resource-saving features. In the process of this development, Daihatsu overhauled all aspects of the engine, the transmission, and the body structure, to maximize energy efficiency and achieve almost a 40% increase in fuel efficiency comparison with the Mira 2WD/CVT without idle reduction functions.
Daihatsu will introduced the new technology in a fuel-efficient vehicle model due to be released in September this year. The company anticipates that it will be the only gasoline-powered vehicle delivering fuel economy of 30 kilometers per liter (equivalent to 71 mpg US or 3.3 L/100km) in JC08 mode. This new mini vehicle will have an entry price of less than ¥800,000 (US$10,200).
The main features of :S Technology include:
A new engine with maximized combustion efficiency and minimized energy loss. Combustion efficiency has been boosted through eight main improvements, including an enhancement in the compression ratio from 10.8 to 11.3 and the downsizing of the particles sprayed from the injector.
The engine uses an i-EGR system. It applies the ion current combustion control, in which ions in the combustion chamber are used to identify the state of combustion, to EGR control. Through close control according to engine characteristics, EGR gas is fed in larger quantities to massively reduce the pumping loss.
Mechanical loss has been minimized by combining 11 improvements, including a reduction in chain tension by cutting the chain width, a tension reduction in the piston rings and modification of the oil seal.
An electronic throttle body made of a lightweight resin has been utilized. Coordinated control of the engine and the CVT using the electronic throttle is performed precisely according to the speed range to maintain a state of the highest efficiency, irrespective of the gear ratio in the CVT.
Thermal management. The layout of the bumper openings and air cleaner ducts has been optimized and the air flow route has been improved to implement thermal management and lower the temperature of the intake air into the engine. A decline in air intake volume resulting from volume expansion of the intake air is suppressed to boost the engine combustion efficiency.
Continuously variable transmission (CVT) with higher power transmission efficiency. Power transmission efficiency has been increased by combining eight improvements, including utilizing a high efficiency oil pump and lowering the CVT control pressure. The engine load has been lowered by optimizing the transmission gear ratio on the basis of increased power transmission efficiency, reduced running resistance and vehicle weight cuts.
The shell body has been streamlined without impairing the body rigidity necessary for safety and onboard comfort. This has achieved a weight reduction of approximately 30 kg while maintaining vehicle length. As many components as possible have been made straight in form to reduce reinforcements.
Weight reduction is achieved by redesigning every interior part. For example, a new structure sheet frame is utilized and the thickness of the instrument panel and door trims is reduced. The weight of the CVT unit for idle reduction is cut by utilizing a thinner-walled CVT case, an aluminum oil pump cover and an aluminum planetary carrier, and by introducing integrated molding for the secondary sensing gear and the piston.
Running resistance lowered. Rolling resistance has been lowered by utilizing low rolling resistance tires with new tread rubber, and by enhancing the drive parts. A CAE simulation and a wind tunnel test were conducted in the design phase to improve the forms of the front corners and slow the underfloor flow. Air resistance has thus been reduced.
Energy Management. The new car will be the first CVT vehicle equipped with the pre-stop idle reduction function, Daihatsu says. It applies a brake and stops the engine when the vehicle speed is 7 km/h or less to increase the idle reduction duration and improve fuel efficiency.
Dedicated components for idle reduction systems have been decreased to achieve weight and size reductions. An ECU for the CVT has been incorporated into the idle reduction computer integrated with auxiliary power supply to prevent the navigation system from being reset upon engine restart.
The function of converting the kinetic energy of the slowing vehicle into electric energy with an alternator and feeding it back into the battery has been enhanced. The power output of the alternator at the time of vehicle slowdown has been increased and the charge acceptance properties of the battery have been improved to substantially cut power generation from the alternator at the time of normal operation and acceleration, and to reduce the burden on the engine.
Source: Green Car Congress
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