Rather old but interesting photos and info. (requires Adobe Acrobat):
cse.polyu.edu.hk
Note the reference to four-stroke commercialisation below:
"Other two-stroke and directinjection four-stroke applications are in various stages of commercialisation"
Direct Injection as a Retrofit Strategy for Reducing Emissions from 2-Stroke Cycle Engines in Asia
Dr. Bryan Willson Professor & Research Director, Engines & Energy Conversion Laboratory Department of Mechanical Engineering, Colorado State University Fort Collins, CO 80523-1374 USA
E-mail: Bryan.Willson@colostate.edu
ABSTRACT
There are an estimated 70-100 million 2-stroke cycle engines in Asia, powering motorbikes, mopeds, threewheelers, tuk-tuks, and tricycles. These 2-stroke engines are characterized by very high levels of hydrocarbon (HC), carbon monoxide (CO), and particulate (PM) emissions. These high emissions levels are primarily caused by scavenging losses produced when the fresh air/....
...There several manufacturers of highpressure direct injection equipment for four-stroke automotive engines, a technology known as Gasoline Direct Injection , or GDI. A second alternative uses compressed air to break up the fuel droplets. This is known as air atomisation or air blast fuel injection. This technology was developed by the Orbital Engine Company in Perth, Australia and is referred to as the Orbital Combustion Process (OCP). The fine atomisation produced by the Orbital air-assisted fuel injection system is illustrated in Figure 2 above. The results of the Orbital OCP system on a 150 cc engine in a typical 3-wheeler application are documented in Table 2. These results show that the use of direct injection reduces CO by 37%, HC by 75%, and improved fuel economy by 36%. Results later in the paper will show that even greater improvements can be achieved through the use of an oxidation catalyst. Further improvements without a catalyst may be achievable by optimising the injector location, port geometry, and shape of the piston crown. The system is in commercial use in two-stroke engines sold by Mercury Marine (the Optimax engine), Bombardier-Rotax, Tohatsu, Aprilia, Piaggio, and Peugeot Motocycles . Other two-stroke and directinjection four-stroke applications are in various stages of commercialisation. The durability of the Orbital OCP system has been demonstrated by durability tests9 and by the successful conclusion of a large fleet trial. In this trial, 100 Ford Festiva vehicles were equipped with two-stroke Orbital engines. These vehicles accumulated over five million kilometers of operation and reported excellent reliability and durability.10 Finally, the Orbital OCP system has now been in use for over fives years on Mercury Optimax outboards with generally excellent reliability. |
