where is torque created?
10-20-05, 12:24 AM
#1
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where is torque created?
i am doing a speech on rotary engines and i would like to know where exactly is the torque being created?
i have a book that says that the torque is created over 2/3 of each shaft rotation
does this mean that the torque is created from 2/3 rotation of the rotor?
would also like a source if you know of one
i have a book that says that the torque is created over 2/3 of each shaft rotation
does this mean that the torque is created from 2/3 rotation of the rotor?
would also like a source if you know of one
10-21-05, 11:33 AM
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http://www.der-wankelmotor.de/Techni...echnungen.html
Translated from babel fish:
I think the eccentricity is 15 for mazda engines.
Translated from babel fish:
"For the computation of the torque, the achievement and medium pressure of the wankel engine the same formulas apply, how those 4 clock lifting cylinder engine!
Whereby the resulting pressure can be computed from the following diagram.
The torque is calculated by p1 time 1= e sin 2 alpha for m.
Whereby e is the eccentricity.
p2m2= e sin (pi/3 - 2 alpha)
p3m3= e sin (2pi/3 - 2 alpha)
p1.2.3= the respective pressure in the chamber
m1.2.3= the resulting torque"
Whereby the resulting pressure can be computed from the following diagram.
The torque is calculated by p1 time 1= e sin 2 alpha for m.
Whereby e is the eccentricity.
p2m2= e sin (pi/3 - 2 alpha)
p3m3= e sin (2pi/3 - 2 alpha)
p1.2.3= the respective pressure in the chamber
m1.2.3= the resulting torque"
Last edited by Eson; 10-21-05 at 11:36 AM.
10-25-05, 07:52 PM
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Feel free to correct or quote me on any of this.
The eccentric shaft turns at three times the speed of the rotor. Because it has one eccentric on it, said eccentric has to be in the same position for each of the three faces of the rotor to be in the correct orientation for their respective cycles.
Pineapple racing has sponsored rotaryengineillustrated.com's great 3.5 MB video you can download and look at an accurate computerized movie of just this phenomenon.
Here's a link to a page with the movie
http://www.rotaryengineillustrated.c...tions/RE3a.php
Pics
http://www.rotaryengineillustrated.com/re101/cycle.php
But where is the torque created? In a piston engine, whose pistons produce thrust but no torque at all, but have their linear motion translated into angular (circular) motion by the crankshaft and connecting rods.
The rotary engine's combustion pressure on its rotors produce a force that is part torque, part thrust, so that it is a smoother transition for the geared eccentric to translate the thrust forces produced into torque because of some of the force produced, due to the shape of the rotor and the chamber in which it resides, is already expressed as torque. The combustion pressure is doing work on the rotor by trying to rotate it, and by moving its center of mass over at the same time.
As a result, a single rotor rotary will be far smoother, (as in, magnitude of its angular and linear vibrations) per unit of mass or power output, than a single piston engine if both have no balancing done to them. In other words, a piston engine has vibrations from the pistons slamming up and down, and from the twisting forces of its once-every-two-crank-rotations power spike.
The rotary also produces three power strokes per rotor rotation, or, one power stroke per eccentric shaft rotation per rotor. So a three-rotor rotary engine will have three power strokes per eccentric shaft rotation, versus a three- piston four-stroke engine's 1.5 power strokes per crankshaft rotation.
My opinion:
Rotary engines are a middle ground between piston engines and turbine engines.
They have a power-to-weight ratio lower than a turbine engine, but higher than a typical piston engine.
They have al specific fuel consumption lower than a turbine engine, but higher than a piston engine.
They also have an MTBFR (Mean Time Between Failure) that is lower than a turbine, but, again, higher than a piston engine of similar application. (you don't find too many piston engined sports cars whose motors last 175,000 miles between rebuilds)
For their size, they use less air than a turbine engine, and more than a piston engine.
They have more major moving parts than a turbine, and less than a piston engine.
In my biased opinion, the rotary is the sexiest motor you can use, because it has some of the behaviors and characteristics of the exotic turbine engine, an unbelievably distinct shriek if unmuffled, and is lightweight, but not hard to work on or repair.
The eccentric shaft turns at three times the speed of the rotor. Because it has one eccentric on it, said eccentric has to be in the same position for each of the three faces of the rotor to be in the correct orientation for their respective cycles.
Pineapple racing has sponsored rotaryengineillustrated.com's great 3.5 MB video you can download and look at an accurate computerized movie of just this phenomenon.
Here's a link to a page with the movie
http://www.rotaryengineillustrated.c...tions/RE3a.php
Pics
http://www.rotaryengineillustrated.com/re101/cycle.php
But where is the torque created? In a piston engine, whose pistons produce thrust but no torque at all, but have their linear motion translated into angular (circular) motion by the crankshaft and connecting rods.
The rotary engine's combustion pressure on its rotors produce a force that is part torque, part thrust, so that it is a smoother transition for the geared eccentric to translate the thrust forces produced into torque because of some of the force produced, due to the shape of the rotor and the chamber in which it resides, is already expressed as torque. The combustion pressure is doing work on the rotor by trying to rotate it, and by moving its center of mass over at the same time.
As a result, a single rotor rotary will be far smoother, (as in, magnitude of its angular and linear vibrations) per unit of mass or power output, than a single piston engine if both have no balancing done to them. In other words, a piston engine has vibrations from the pistons slamming up and down, and from the twisting forces of its once-every-two-crank-rotations power spike.
The rotary also produces three power strokes per rotor rotation, or, one power stroke per eccentric shaft rotation per rotor. So a three-rotor rotary engine will have three power strokes per eccentric shaft rotation, versus a three- piston four-stroke engine's 1.5 power strokes per crankshaft rotation.
My opinion:
Rotary engines are a middle ground between piston engines and turbine engines.
They have a power-to-weight ratio lower than a turbine engine, but higher than a typical piston engine.
They have al specific fuel consumption lower than a turbine engine, but higher than a piston engine.
They also have an MTBFR (Mean Time Between Failure) that is lower than a turbine, but, again, higher than a piston engine of similar application. (you don't find too many piston engined sports cars whose motors last 175,000 miles between rebuilds)
For their size, they use less air than a turbine engine, and more than a piston engine.
They have more major moving parts than a turbine, and less than a piston engine.
In my biased opinion, the rotary is the sexiest motor you can use, because it has some of the behaviors and characteristics of the exotic turbine engine, an unbelievably distinct shriek if unmuffled, and is lightweight, but not hard to work on or repair.
Last edited by Smilodon; 10-25-05 at 08:02 PM.
10-26-05, 12:23 AM
#6
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"The rotary engine's combustion pressure on its rotors produce a force that is part torque, part thrust, so that it is a smoother transition for the geared eccentric to translate the thrust forces produced into torque because of some of the force produced, due to the shape of the rotor and the chamber in which it resides, is already expressed as torque. The combustion pressure is doing work on the rotor by trying to rotate it, and by moving its center of mass over at the same time."
The pressurized rotor face typically has a uniform pressure across it. Since it is perched on a central eccentric bearing, there in no rotor experiencing torque. It's just how well that face is lined up with the eshaft, that determines torque that is applied to the eshaft. Just like pistion engine, no torque to eshaft occurs at tdc or bdc positions of the rotor face.
Rotary eliminates the conrod "middleman" , but in a similar way the force vector orientation relative to the eshaft position will determine where the eshaft is most effectively torqued by the rotor face. Like a piston engine , this is about 1/3 thru the power stroke.
The pressurized rotor face typically has a uniform pressure across it. Since it is perched on a central eccentric bearing, there in no rotor experiencing torque. It's just how well that face is lined up with the eshaft, that determines torque that is applied to the eshaft. Just like pistion engine, no torque to eshaft occurs at tdc or bdc positions of the rotor face.
Rotary eliminates the conrod "middleman" , but in a similar way the force vector orientation relative to the eshaft position will determine where the eshaft is most effectively torqued by the rotor face. Like a piston engine , this is about 1/3 thru the power stroke.
10-26-05, 03:12 PM
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I agree. There is fairly uniform pressure across the face of the rotor, and, the rotor is not experiencing torque directly. Neither are the fan blades in a turbine engine experiencing torque. It is only because the turbine blades are attached to the central shaft that they translate the aerodynamic forces within the engine into torque.
So, The force applied to the rotor is partially directly turned into torque by its interface with the gear, and partially turned into thrust and torque by its interface with the eccentric. But, yes, the force initially starts out at as just a random combustion pressure. As it does in any motor that burns fuel to create heat and pressure.
Thank you for clarifying.
So, The force applied to the rotor is partially directly turned into torque by its interface with the gear, and partially turned into thrust and torque by its interface with the eccentric. But, yes, the force initially starts out at as just a random combustion pressure. As it does in any motor that burns fuel to create heat and pressure.
Thank you for clarifying.
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10-26-05, 10:48 PM
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10-27-05, 12:02 AM
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Hey, that's neat. What are the dashed lines? I would guess that the two dashed lines are (top one) the gross power and (bottom one) energy required for the motor to turn its own guts, and the solid line is the resultant?
Because the solid line looks like a resultant of combining the two dashed ones.
Because the solid line looks like a resultant of combining the two dashed ones.
Last edited by Smilodon; 10-27-05 at 12:09 AM.
10-27-05, 12:20 AM
#10
Rotary Enthusiast
Originally Posted by Smilodon
...... So, The force applied to the rotor is partially directly turned into torque by its interface with the gear, and partially turned into thrust and torque by its interface with the eccentric. But, yes, the force initially starts out at as just a random combustion pressure. As it does in any motor that burns fuel to create heat and pressure..
There is, in steady state constant rpm torque generation, no load at the stationary gear teeth, and no related torque factor. It's all about centered rotor face force vector, and relative e-shaft position. The gear is more like a timing chain type function, not related directly to torque creation.
The gear mesh does see loads due to brief non-uniform pressure distributions across the long side of the rotor face ie initial port opening and inital flame front spread.
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