An anonymous reader writes: A California inventor is developing a new compact and highly efficient engine — the Massive Yet Tiny (MYT) engine — that promises high power output with a very high power to weight ratio (20:1). The inventor, Raphial Morgado, recently won first prize in the 2005 Emhart-NASA Tech Briefs Design Contest for his work on the engine.
The engine moves pistons on different rotors relative to each other to form combustion chambers of variable volume in a toroidal cylinder. The pistons move in stepwise fashion, with the pistons on one rotor travelling a predetermined distance while the pistons on the other rotor remain substantially stationary.
Fuel is drawn into a chamber as one of the pistons defining the chamber moves away from the other, and then compressed as the second piston moves toward the first.
The cycles of the MYT engine. Click to enlarge.
Combustion of the fuel drives the first piston away from the second, and the spent gases are then expelled from the chamber by the second piston moving again toward the first. An output shaft is connected to the rotors in such manner that the shaft rotates continuously while the rotors and pistons move in their stepwise fashion.
The engine fires 16 times on one revolution of the crankshaft, 32 times on two. By comparison, a standard V8 fires four times per crankshaft revolution — one-quarter the number of the MYT. Angel Labs, the company developing the engine, calculates the equivalent displacement of the MYT as 848 cubic inches (13.9 liters), with a 3-inch bore and a 3.75-inch stroke. The company further calculates that the 14" x 14", 150-pound prototype could produce power in excess of 3,000 hp.
[The 3,000 hp rating] is conservatively estimated from 850 CID. A conventional engine can produce 4 hp per CID (when turbo charged). Four times 850 [the equivalent displacement] is more than 3,000. Our data of air motoring (800 lb.ft. of torque from 150 psi of compressed air) extrapolates to more than 4,000 lb.ft. of torque when fuel is ignited, exceeding our conservative estimate.
— Jin K. Kim, Managing Member, Angel Labs
The design is also modular. Additional MYT units can be connected by removing the rear cover of the engine and connecting another ME chamber assembly. With a dual-assembly configuration, the engine becomes a "64-cylinder" engine with 1,695 cubic inches displacement (27.8 liters), raising the power-to-weight ratio up to a projected 40:1.
The engine uses only about 20% of the number of parts normally found in a reciprocating internal combustion engine, and only 12 of the MYT parts are moving parts, reducing friction and parasitic losses.
Unlike a reciprocating combustion engine, the MYT engine permits a piston dwell at the equivalent of Top Dead Center (TDC) — the starting point for combustion. The current prototype is set for a piston dwell of approximately 12 degrees of the crankshaft rotation. By adding in that delay under combustion before permitting the power stroke, the MYT burns a greater percentage of the fuel and air mixture in the combustion chamber, resulting in a more complete combustion.
All we know is that 12-degrees dwell at the TDC, which no other engine can do, will burn all the fuels completely. Therefore, we expect very clean emissions.
— Jin K. Kim
Other features of the engine include:
The ability to support a compression ratio as high as 70:1.
No valves. The MYT uses open ports with no restriction. Airflow action is one way.
The entire engine acts as a heat sink and a radiator. It is both air and oil cooled.
There is no thrust loading on piston skirts.
Pistons do not touch the cylinder walls, only the rings do.
Pistons travel only the same direction. No reciprocation, only stop and go.
There are no cylinder heads, no cam shaft, no valves (the ME is equivalent to the bottom end of a reciprocating engine).
Intake compression and power stroke and exhaust stroke events are happening all at the same time, so there are no load strokes.
The MYT engine is not the first implementation of rotating pistons in a toroidal cylinder — the 1968 Tschudi engine is very similar in concept. (A newer derivative is by Hoose, 2005.) The key to the MYT engine is its timing mechanism.
The stop and go actions can be generated in many different ways, but you can not have active locking mechanism, because it will break under repeated stress. It took Raphial, who usually can invent in a couple of hours per invention, more than two years to come up with this invention (he threw away about 10 different ways of implementation.)
— Jin Kim, in the Angel Labs forum
Angel Labs is targeting a number of application: autombiles and trucks, pumps and compressors, aviation (helicopter, fixed wing and UAV), and military. Their goal is to license the technology non-exclusively to everyone. According to Jin Kim, Angel Labs is currently in discussions with Lockheed Margin, Boeing, Ford and several smaller potential licensees.
(A hat-tip to Bob C!)