Big clumsy cam followers-2nd attempt

[Bengy2]

My recent thread (404-120198) outlined a design problem I have been unable to solve.

OK Folks, I have been thinking and will now try once again and "look outside the box" as you correctly sugest.

I am trying to use a Scotch Yoke as a mechanism to vary the output speed from a constantly rotating input shaft. i.e. the crank of the scotch yoke rotates at a constant rate, the yoke reciprocates and this reciprocating movement is converted to a continuous rotary motion. The problem is that the output from a scotch yoke is sinusoidal and I would prefer linear(uniform) rotary motion at the output. I have been trying to achieve this by moving the reciprocating yoke back and forth at a uniform rate. This is far from easy given the limitations on space, costs etc. So now I will retry looking at the output of the system.

The question is if the above system were coupled to a conventional IC engine and used to transmit power to the wheels of a vehicle would this sinusoidal motion have a noticable effect at the wheels. By that I mean would the ride quality be diminished in any way. If it were not then I am treating a "nice to have" as a "need to have" and could possibly ignore it.

If it is a problem and I want to fix it could I install some sort of damping system to the output shaft, I was thinking along the lines of some sort of Torsion Bar setup.

This might be better posted in the Automotive forum but I'll see how I get on here first.

Your assistance would be grateully apreciated,
Bengy2

 

[Barry1961]

The old Stober traction drive is only good to around 10hp but here is the link.

http://www.stober.com/power/adjust_speedoper.htm

What kind of speed, speed range and torque are you looking for?

Can you vary the OD of the tires with balloon, cone or tilt?

Barry1961

 

[zekeman]

What kind of speeds, torques are you "torqueing" about. The short answer to your need for linearity is you don't, since a properly designed flywheel can filter out your speed/torque cyclic variations. It seems to me that you have a bigger problem,if the speeds are great enough, i.e. inertia shaking forces that must be balanced, the same problem that is already solved in the IC engine.
By the way how do you get a "constant" speed source for the output of an IC engine?

 

[MikeHalloran]

WRT noticing rapid speed fluctuations at the wheels, if you're designing a dirt bike to be used in low traction conditions like sand or mud, it may not matter. Apocryphal reports say that single cylinder motorcycles do better in the boonies, because alternating stick- slip amounts to cheap traction control.



Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA

 

[Bengy2]

Thanks all for the replies, I'll reply in more detail in a day or so when I've had a chance to study them in detail.

 

[Bengy2]

As promised here are some additional pieces of information to clarify some points raised:

The IC engine in this particular case will be 2litre but this may vary so I would like a design that will be flexible. The traction conditions will not be such that speed/torque variations can be absorbed, I need to filter them out if they are noticable

In reply to ZEKEMAN By the way how do you get a "constant" speed source for the output of an IC engine? - I will not be doing anything with the output of the IC engine, just using it as a power source and connecting it directly to the rotating crank of the scotch yoke and looking to filter out any cyclic variations in the output speed/torque.

Zekeman, you are tackling my problem directly and the idea of the flywheel sounds good. The question now is:

a)Will a flywheel on the output shaft work if the output speed/torque is variable (via adjusting the Scotch Yoke)
If it will then I can start to consider how to balance the forces of inertia etc. but I'll leave it at that for now.

Once again sincere gratitude to all respondents for your contributions.

Bengy2