Variable Cam Stuff

[Raymond C Drouillard]

On Thu, 02 Jul 1998 14:35:35 -0800 Ludis Langens <ludis at cruzers.com>
writes:
>Frederic Breitwieser <frederic.breitwieser at xephic.dynip.com> wrote:
>> But, basically is nothing more than adding a few links to the timing
chain, 
>> pinching it with two gears that are at a fixed distance, and sliding
the gears 
>> left and right across the front of the engine.  By doing so, the
relationship 
>> between the crank and the cam adjust "on the fly".  We used simple
hydralics 
>> to move the two gears, and it worked pretty good.
>
>This same subject came up on the list a long time ago.  At the time, I
>had needed to loosen quite a few CV axle nuts, and had to deal with
>motion through a differential.  Putting 2 and 2 together led to an idea
>of how to do variable cam timing:
>
>Attach a small differential to the end of a cam.  The cam is connected
>as one (half)axle.  The "drive shaft" input connects to the timing chain
>/ belt / self-destructing-fiber-gear.  Now connect a small electric
>stepper motor or solenoid as the other (half)axle.  This motor/solenoid
>only needs to turn a few degrees.
>
>A computer can now control the motor/solenoid to adjust the cam timing. 
>A one degree movement in it will cause the cam timing to adjust by one
>degree in the opposite direction.  The chain/belt/gear still provides
>all the normal cam motion.  Thus, if the computer fails, the engine will
>still run.  (As opposed to a cam driven just by an electric
>motor/stepper.)
>
>On a DOHC engine, attach one of these gizmos to each cam.  If the intake
>and exhaust valves are controlled by opposite cams, the intake to
>exhaust timing relationship can now also be controlled.
>
>-- 
>Ludis Langens                               ludis (at) cruzers (dot) 
>com
>Mac, Fiero, & engine controller goodies:  
>http://www.cruzers.com/~ludis/

I like that idea!  It should work well.  The only challenge would be
getting it to physically fit the area available.

Another variation on that idea would be a planetary gear system.  Drive
the sun gear with the engine crank, and use the planet gears to drive the
cam.  Move the ring gear back and forth (with a stepper motor or
hydraulically) to advance or retard the cam.

Ray Drouillard

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