What if camshafts weren't the way they are presently designed. Instead, What if they were mini cranks with the valves attached like the pistons. This should in turn eliminate valve float and possibly have many more benefits right?

 

soo are you going to pass the blunt or what?

 

MMMM blunt...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Like Butter &raquo;</TD></TR><TR><TD CLASS="quote">What if camshafts weren't the way they are presently designed. Instead, What if they were mini cranks with the valves attached like the pistons. This should in turn eliminate valve float and possibly have many more benefits right?</TD></TR></TABLE>

Valves are not in continuous motion, unlike pistons which are.

I'll take the blunt now, please.

.............

Now, instead of using a camshaft at all, why don't we find an alternate way to open and close the valves. Like pneumatics. That way, it could be completely controlled, and optimal for all driving conditions at all time. Screw vtec, and only have 2 cam profiles, lets have infinite. Oh wait, thats been done before.

 

pass the crack pipe. blunts are for pussies! shoot me up with some H! ah fo rale doe!

 

Already been done. Ducati desmo dronic. Uses cams to open and cams close the valves. Valve float imposible. Dan

 

desmodromic = In mechanical terms, the word desmodromic is used to refer to mechanisms that have different controls for their actuation in different directions.

Here are a few clarifying examples:

imagine a saw cutting a tree trunk: the act of pushing and pulling the saw is a desmodromic action.

By contrast, the movement of a door handle is not controlled by a desmodromic mechanism: this motion is only controlled in one (opening) direction, while the return is automatically obtained via a spring, in a less controlled manner.


To obtain good results with a spring system, it is necessary to find a compromise between heavier spring loading requirements (possibility to turn at high RPM, while preventing valve bounce) and lighter spring loading requirements (loss control, loss being the amount of work necessary to open the valves against the spring loading: it should be remembered that the camshaft is driven by the engine; and smaller sizing of the parts involved, proportional to the spring loading).

These problems are all solved by a desmodromic system: smoothness (and consequently, decreased losses) at low RPM and reliability at high RPM (without valve bounce) are obtained.

Quoted from How stuff works


Thats interesting, but its not exactly held togeather like a connecting rod. Its more like our current cam design except its a springless sytstem that does its own lifting of the valve.

Imagine it like having rocker arms above and below the cam, the bottom one pushes the top of the valve, the top one pulls the valve back up.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hAILO &raquo;</TD></TR><TR><TD CLASS="quote">desmodromic = In mechanical terms, the word desmodromic is used to refer to mechanisms that have different controls for their actuation in different directions.

Here are a few clarifying examples:

imagine a saw cutting a tree trunk: the act of pushing and pulling the saw is a desmodromic action.

By contrast, the movement of a door handle is not controlled by a desmodromic mechanism: this motion is only controlled in one (opening) direction, while the return is automatically obtained via a spring, in a less controlled manner.


To obtain good results with a spring system, it is necessary to find a compromise between heavier spring loading requirements (possibility to turn at high RPM, while preventing valve bounce) and lighter spring loading requirements (loss control, loss being the amount of work necessary to open the valves against the spring loading: it should be remembered that the camshaft is driven by the engine; and smaller sizing of the parts involved, proportional to the spring loading).

These problems are all solved by a desmodromic system: smoothness (and consequently, decreased losses) at low RPM and reliability at high RPM (without valve bounce) are obtained.

Quoted from How stuff works


Thats interesting, but its not exactly held togeather like a connecting rod. Its more like our current cam design except its a springless sytstem that does its own lifting of the valve.

Imagine it like having rocker arms above and below the cam, the bottom one pushes the top of the valve, the top one pulls the valve back up. </TD></TR></TABLE>

That's incredible. Now, who wants to buy me one?

Though, I wonder what happens when you start to get wear in the system. With a traditional setup, cams, valves, and springs, as they wear, you just get a little less valve opening as parts wear. If you don't have a spring to hold the valve tightly closed, what happens when you get a little play in the parts? I mean, when I did a valve job, I set a specified clearance between the cams and the rockers. Now 0.007" between the cam and the rocker is fine, because the valve is fully closed without intervention. But, without a spring, a similar clearance could leave the possibility of 0.007" valve opening...

 

desmodronic if im not mistaken hade been invented way back in the day with some of the first race cars that had those skinny assed tires. i believe i read that in some v8 mag.

 

one idea that i had about 6 years ago before i found out later that they are already working on is valve control via solenoids. just like your injectors are timed in pulsed so could your valves and along with that you would not have a camshaft designed for one rpm range. with a shitload of time you could tune it for the entire rpm range in theory a very flat torque band until other factors such as the head, intake mani, exhaust mani would limit it's potenial rpm range. would be nice eh.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by minimesleeper94 &raquo;</TD></TR><TR><TD CLASS="quote">one idea that i had about 6 years ago before i found out later that they are already working on is valve control via solenoids. just like your injectors are timed in pulsed so could your valves and along with that you would not have a camshaft designed for one rpm range. with a shitload of time you could tune it for the entire rpm range in theory a very flat torque band until other factors such as the head, intake mani, exhaust mani would limit it's potenial rpm range. would be nice eh.</TD></TR></TABLE>

I guess they have those already, but the bulk required for solenoids powerful enough to move the valves almost ends up defeating their purpose. I guess there's some other problems...due to their nature of cams, the valves get seated relatively soft instead of slamming into the head. This becomes a problem with solenoids.

 

Del West Engineering has been working on this for a while, but i don't know about there reliability and durability. Looks promising but really expensive.

Here's a link to their pneumatic solenoids: http://www.delwestusa.com/manu...s.asp