PGO working on rotary valve scooter engine
Came across this item on the autobloggreen.com blog this morning. I must say that this is an interesting variation of the over a century old idea of a sleeve valve engine. These early sleeve engines used a sleeve or sleeves that were concentric with the centerline of the piston and moved either axially to the piston, in the case of the two sleeve engine, or axially and rotationally, in the case of the single sleeve engine. These early engines suffered problems because of the reciprocal nature of their valve system, i.e, the constant “stopping and starting” and the wear that comes with it. (Go to http://en.wikipedia.org/wiki/Sleeve_valve to read about these early engines.) This variation uses a sleeve, but it rotates around the piston. It has a single opening machined into the sleeve. The engine block has an intake port and an exhaust port located at right angles to each other. The sleeve is driven at half the speed of the crankshaft, just like a conventional cam shaft. As the piston starts down on intake, the opening in the sleeve begins to align with the intake port and fuel/air is drawn into the engine. At mid stroke, the port is fully open, and at the end of the stroke the port is fully closed. Of course, variations of this timing can be made by simply changing the length and positioning of the opening. On the compression and power strokes, the opening in the sleeve is effectively closed by the cylinder wall. When the piston comes up on exhaust, the opening aligns with the exhaust port and the exhaust gases are expelled, and the whole cycle repeats. This system has value in that head design has more flexibility. The plug can be placed anywhere in the head and various types of “squish” and “swirl” can be used, because there are no valves in the head restricting design. Piston tops will not have to have valve head reliefs cut into them, eliminating their sharp edges that are a prime source of detonation and preignition. Instead of regrinding a cam every time different valve timings are required, the engine builder simply cuts a different sized or located hole in the sleeve. I think it merits further development.
PGO working on rotary valve scooter engine
Filed under: Emerging Technologies, On Two Wheels
The good ‘ol four stroke internal combustion engine has life left in it. Despite the fact that the world’s oil supplies are getting more expensive and harder to extract, the short-term truth is that there’s still no cheaper way to power a vehicle than with petroleum. This being the case, engineering work is still being done on the basic design of the engines that power our cars, motorcycles and scooters. Further proof of this truth comes by way of Taiwanese scooter manufacture PGO, which has partnered up with RCV Engine Ltd. of the U.K. The two firms are working on rotary valve technology for scooters. So far, the rotary valve engines have really only made waves in the model aircraft industry, a market that RCV is very active in, but PGO believes the engines in the 125-150cc range could power its scooters.
The technology seems rather elegant and does away with the valvetrain of a four stroke engine, a major source of losses and maintenance. The cylinder, including the combustion chamber, rotates around the piston as it moves through its stroke. Click here for more details on how the technology works. PGO hopes to reduce the costs of engine manufacturing while increasing power and lowering emissions. So far, though, no specific engines have been announced.
[Source: CENS via 2 Stroke Buzz]
Source: http://www.autobloggreen.com/2008/10/23/pgo-working-on-rotary-valve-scooter-engine/