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CRT looks promising in achieving clean Diesel emission particularly PM, however, it presents two limits in exhaust gas temperature levels, i.e., at idling to low power region requiring emission temperature 260°C minimum, and at high power region 450°C maximum. These problems can only be solved by the proposed method under the currently available known technologies. At the lower power side, 260°C minimum, can be materialized by the use of “Exhaust Secondary Cam (ESC)”, throttling intake air and exhaust gas lines together with other means like reduction of number of cylinders in operation. At the high power side, 450°C maximum, will easily be cleared by “Hyperbrid supercharging system” invented by the author.

Supercharging system is obviously a necessary technology for heavy duty vehicular diesel to meet future stringent emission regulation as well as to improve fuel consumption characteristics. Although the conventional exhaust turbocharger system improves fuel consumption, there are some problems such as having a difficulty in improving starting acceleration and smoke emission characteristic because the response of an exhaust supercharger is not enough. On the other hand, the conventional mechanical supercharging system seems to be a quite effective aid for acceleration ability. However, it does not satisfy demand for low fuel consumption characteristic.

Historically Diesel engines with turbocharger (TC) suffer so called “Turbo-Lag”, which presents deficiency in intake air-supply during the low engine speed stage. This insufficient air-supply causes emissions much higher than their normal operating conditions. For this a “Hybrid” supercharge-engine has been proposed [1], where a mechanically driven supercharger (SC) is used during the low engine speed zone. This paper proposes a new EGR (Exhaust Gas Return) system concept applicable to Diesel engines, which will achieve the compatibility to the stringent emission standard of USA in the year 2004, which is more stringent than EURO-3. S.P.Edwards et al [2] discussed some measures to clear EURO-3 values are discussed, but those, “D” and “E” in the Figure 1 are not possibly achievable in the near future. Therefore only EGR among those discussed in the paper is realistic.

This paper proposes a new flexible system concept applicable to diesel engines which will achieve the compatibility of high BMEP (Break Mean Effective Pressure) and low fuel consumption. The high BMEP means constant power from low speed to high speed (the power density will be 60ps/liter for truck applications, 87ps/liter for marine applications and 109ps/liter for racing boats). BMEP will be over 32kg/cm2. The low fuel consumption means a wide range of speed and torque having a good match to the best turbocharger efficiency. Before feasibility testing of an engine a basic simulation has been done and is introduced in this paper.

The Miller cycle was applied to a turbo-charged 324 kW gas engine with three-way catalyst. Three different methods of the Miller cycle were applied, the Early Rotary-Valve Closing (ERVC), Late Intake-Valve Closing (LIVC) and a combination of the ERVC and LIVC methods. The effect of the methods on engine performance was extensively investigated. The experimental results demonstrate a promising performance of the LIVC method, which substantially improves the thermal efficiency up to 38%, compared to 34% by the conventional Otto Cycle. The LIVC method is expected to improve engine performance with inexpensive modification. The combination of the ERVC and LIVC methods appears to further improve thermal efficiency.

A gasoline engine with an entirely new combustion cycle deriving from Miller Cycle is developed. By delaying closing timing of intake valve and with new Lysholm Compressor which provides higher boost pressure, engine knocking is avoided while high compression ratio is maintained and approximately 1.5 times larger toque than that of a naturally aspirated(NA) engine of the same displacement is realized. This V6 Miller Cycle gasoline engine can be the alternative to a larger displacement NA engine because of its equivalent torque performance and its lower fuel consumption by the effect of smaller displacement.

High performance automotive engines are required to overcome the environmental problems and to achieve less fuel consumption. For the realization of such engines, the high efficiency Lysholm (screw type) compressor was developed and its mass-production has been started, which can produce high pressure boost for the engine in whole engine speed range. This compressor has achieved high volumetric efficiency and the adequate durability for automotive use has also been confirmed through various kinds of tests.

A gasoline engine with the expansion ratio of 14:1 for better efficiency is presented. The engine has intake control rotary valves to reduce the effective compression ratio for knock avoidance and to cotrol power output. Computer simulation, based on the method of characteristics and quasi-steady model, indicated the advantage of the rotary valve system as well as the optimum design of the valve actuation. Experimental results showed a good agreement with the prediction, and BSFC of under 240 g/kWh was achieved at load higher than 50%. However, at very light load, the conventional throttle valve operation was inevitable, which somewhat worsened the advantage of the new system. The mileage for a car driving cycle and constant speeds were also estimated and it was forecast that optimized supercharging would significantly benefit the fuel economy.

The Miller system was implemented to control the intake-air throttle valve for a stationary natural gas engine. The throttle system consists of an additional rotary valve provided with a variable timing device and a conventional butterfly valve. This throttle system can control not only the mass flow rate of the air-fuel mixture by changing the intake duration, but also the effective compression ratio at the same time. The experimental results showed an improvement in thermal efficiency at part load and a reduction of NOx emissions for the gas engine.

This paper deals with a new type of Miller cycle engine which is installed with an intake control rotary valve, and presents the experimental investigation on the test engine which was undertaken to examine the capacity of supercharging as well as fuel economy in the application of the new system to small-sized gasoline engines. An experimental investigation on the test engine with some simple modification to a conventional engine revealed that the intake control rotary valve installation is quite effective to control the virtual compression ratio. It was ascertained by an external supercharging test that reduced compression ratio with constant expansion ratio allowed the test engine to obtain a considerably higher level of torque in the low engine speed range than had been attained in conventional supercharged engines without any increase in fuel consumption.

The choice of cam profile is a matter of primary significance in the procedure of valve gear design. It is long since dynamic design methods were first proposed and used, but even so, shortcomings still exist. One is that the conventional method does not take into account the non-linearity and hysteresis characteristics of valve train stiffness. This paper describes a new dynamic design method of determining cam profile, including the ramp period, in which the above hysteresis characteristics as well as other factors are reasonably taken into consideration. Experimental investigations have shown that the new method is effective over a wide range of operating conditions.