Model aircraft engine with exhaust control mechanism

Details Model aircraft engine with exhaust control mechanism Model aircraft engine with exhaust control mechanism

1999-04-16

2000-04-25

Dolinar, Andrew M.

Internal-combustion engines

Engine speed regulator

Responsive to deceleration mode

123DIG3, 2988801, 188273, F02D 904, F02D 914

Patent

active

060531460

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates to engines for model aircraft, and particularly, to exhaust control systems for model aircraft engines. More particularly, the present invention relates to throttle and muffler systems for use with model aircraft engines in small radio-controlled model helicopters.
Model aircraft engines typically include a carburetor for mixing air and fuel, an ignition source (e.g., a glow plug), a piston cylinder where the air and fuel are combusted, and an engine exhaust port where engine exhaust from the combusted air and fuel exits the model aircraft engine. Sometimes a muffler is provided to quiet the exhaust gas produced by the model aircraft engine.
A throttle is provided on some model aircraft engines so that a pilot may operate the model aircraft engines at more than one speed. As the model aircraft engine changes speed, the power produced by the model aircraft engine also changes. Adjusting the throttle of the model aircraft engine adjusts the power produced by the model aircraft engine so that the speed at which the helicopter climbs and/or travels may be changed. Throttles are generally situated adjacent to the model aircraft engine inlet to restrict the amount of air entering the carburetor or situated adjacent to the engine exhaust port of the model aircraft engine to restrict the amount of air exiting the engine exhaust port.
The operating speed of most modern throttled model aircraft engines is adjusted by restricting the amount of air entering the carburetor. The primary function of the carburetor, however, is to mix air and fuel. Thus, adding a throttle to the carburetor makes the carburetor considerably more complex. Carburetor-type throttles are also relatively bulky and expensive.
Model aircraft engines can also be throttled by means of a conventional exhaust restrictor throttle mechanism. Exhaust restrictor throttle mechanisms throttle model aircraft engines by restricting the flow of exhaust gas out of engine exhaust ports formed in the model aircraft engine. This method of throttling is particularly advantageous for model aircraft engines including glow plugs because heat is retained within the model aircraft engine piston cylinder to keep the glow plug element hot. In addition, restricting the engine exhaust port also reduces the noise level of exhaust gases exiting the engine. Exhaust restrictor throttles tend to muffle engine noise when engine speed is low, as would be expected on a model helicopter when hovering a few feet above the ground.
Typically, conventional exhaust restrictor throttle mechanisms are of the rotary valve type and are situated immediately adjacent to the model aircraft engine exhaust port. Not only does the exhaust restrictor throttle valve in this location become extremely hot, but the choice and orientation of exhaust restrictor throttle valve configurations is limited by the proximity of the model aircraft engine to a valve-actuation mechanism which actuates the exhaust restrictor throttle valve.
Engine throttling is an important function for the proper operation of model helicopters. While a great deal of interest for flying model helicopters exists in the modeling community, radio-controlled model helicopters are typically expensive and complicated. Only a very small percentage of modelers can actually afford to buy a helicopter and fewer modelers are skillful enough to build and fly a model helicopter successfully.
Recent advances in the art of small radio-controlled model helicopters have resulted in a new class of improved small model helicopters that are simple and inexpensive enough to appeal to a wide modeling audience. New features that are incorporated into this new class of improved small model helicopters to simplify and/or reduce the expense of radio-controlled model helicopters and increase the availability of model helicopters to a wider, less sophisticated audience are disclosed, for example, in U.S. Pat. Nos. 5,305,968 to Paul E. Arlton, 5,597,138 to Paul E. Arlton and David J. Arlton, 5,62

REFERENCES:
patent: 2806458 (1957-07-01), Mettetal
patent: 3002506 (1961-10-01), Mocarski
patent: 4321893 (1982-03-01), Yamamoto
patent: 4341188 (1982-07-01), Nerstrom
patent: 4669585 (1987-06-01), Harris
patent: 4903802 (1990-02-01), Takigawa et al.
Cox.TM. Muffler As Modified By John Molnar (photograph).

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