Single Cylinder Engines

Ok, so here's what I've been tasked to do

Build a system to produce smooth sinusoidal oscillations with a
variable stroke of up to 8" and variable frequency up to 30hz. The
driver required will be around 3 hp.

since this is supposed to be running by the end of august, and there
isn't time to machine all the necessary parts, my basic idea was to
cannibalize an existing single cylinder engine and connect the drive
shaft to a D/C or variable speed A/C . The arrangement will require a
connecting rod as the thing that I am driving cannot sustain the side
force. The stroke will be varied by allowing for different
crank arm lengths.

My question is. Where in tarnation do I find a single speed engine
that might be a candidate? Any other ideas for doing this? Any help
you can provide would be greatly appreciated.

Thanks in advance,
Andrew

 

3hp edger or lawnmower engine. Should cost next to nothing.
Rob

 

Unfortunately, a piston driven by a connecting rod and crankshaft will
not produce sinusiodal oscillations.


Matt

 

Andrew,
You could drive a gear reduction box with about a 100 to 1 ratio.. take
the output from a connecting rod affixed to a circular disk on the
output shaft. You could use heim joints for the ends of the rod and make
several holes in the disk to accomodate different stroke lengths. A hole
4" off center will give you an 8" stroke..
A Briggs and Stratton engine with this amount of reduction will give you
like 8 to 36 rpm at the output.
How much power/torque does it have to have?
Paul

 

"Andrew" wrote ...

HI Andrew,
you could vary the stroke more simply and have continuous adjustment by
taking the connecting rod from the cranck to one end of a beam with its
central pivot in a slot, and driving the doohickey with another connecting
rod attached at teh other end.
Umm.... you may want to take a look at the Fuckingmachines website, they've
done a lot of work on variable stroke, variable speed reciprocating
assemblies. Hell, it'll probably give you ideas for the machine you're
building, too.
Hope that helps,
Dave H.

(The engineer formerly known as Homeless)

 

Hmmm, you just made me think of the system used by the Paasche
AB Turbo airbrush. This uses an air jet to spin a turbine with an offset
cam on the axle. The walking rod (?) is fixed at one end (actually, it
is adjustable), the cam is in a slot in the center of the rod, and the
working needle fitting is on the other end of the rod.

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