Hi again, as I am a fan of rotary engines i decided to do my final college exam/work abaout the rotary engine, so my professor gave me an assignment to make a project for a wankel with a target horsepower of 190kW. I've done the description and started to do the calculations.
so my first question would be :
if a is the parallel transfer for the trochoid curve outer envelope, and a' is the parallel transfer of the inner envelope, how much should i take the minimal clerance between the rotor and rotor housing Sp?
i chose a=4mm, but don't know much should be the minimal clearance

 

maybe i should put some more info.
so far these are the basic dimension that i stated in the paper work

e=19,5mm
R=122mm
a=4mm
b=58mm

so basicly i would need to know wich dimensions are usualy taken for minimum clerance Sp, the volume of the spark plug holes Vr, and the volume of the rotor recess.

sorry for the double post but can't see any edit button.

 

^ You can edit for only a short time after you make a post.

and... WHAT THE HECK ARE YOU TALKING ABOUT? "trochoid curve" "inner envelope"... I think I am offended just don't know how or why.

 

to know every single point of the inner side of the housing a parametric formula of the trochoid curve is used, but for the practical use, that trochoid is paralely transfered for a distance and so the parametric formula goes like this:



and fo the rotor shape, it's used the inner envelope of that curve wich parametric formula is a bit more complicated:



so basicaly i cant' move both curves for measure a so another measurment a' is used but i don't know how much in practice

sorry if I offended you or anyone else.

 

I believe your speaking "equation" to mechanics, most of us know tolerances and specs but not many can do this level of math. Perhaps if you "dummied down" the question you'd get more responses. For instance, it seems as though you are looking for the minimal/maximal clearance between rotor and housing.

 

Do you have the equations in polar coordinates? I've done this level of math for my engineering degree, but not this application before. In Chem-E we do so much in polar and cylindrical, I recognize it better. Also for these shapes, I think the equations would be shorter.

 

Do you need to E flat double clutch with that or can you get fries on the side?

 

it's not so much to "dummie down" then it is for me to make a reasonable mechanical sentence in english, the language is also a barrier. but yes, i need the minimal and/or the maximal clearance between rotor and housing.

will try to make it into the polar this afternoon and see what will become of it.
so Chem-E is a program? will try it also, just hoping it isn't too complicated.

 

Sorry, Chem-E is just an abbreviation for chemical engineer. I'm sure a mechanical engineer would be better suited to helping with this, but I'll do what I can.

 

Fortunately, I am an engineer who just happens to like to play mechanic on the side

Electrical engineer though, so this is abit beyond me, plus I can't see your equations in Firefox while running under Ubuntu for some reason. I could earlier today under Windows, go figure. I will peek at them again when I can view them next.

I however, have found on my hard drive 2 PDF copies of Kenichi Yamamoto's (chief of Mazda's Rotary Engine Research Department in the 60's and 70's) text book on the rotary engine. One is 1971 edition, the other is a 1981 edition. Please PM me and I can see how I can get them to you.

 

thank you for your offer but already have them both unfotunatly there are some details missing to make a project. i even failed at turning the equasions to polar....
but i used some aproximations for the dimension....
right now i'm using the lotus program for getting the indicated mean efective pressure. i know it's not for wankel but it's the closest i can get.

Can someone tell what values gets the indicated mean effective pressure in the renesis?

 

I have no idea of the equations you posted but I just keep reading this post thinking I will understand something. ha Either way, very cool to see how other people break down the rotary in different ways.