Huţu GabiCMPA

Tipuri de motoare rotative

1. Motorul Wankel 2. Motorul Kauertz3. Motorul Revetec4. Motorul Webb

Motorul Wankel – av. /dezav.Avantajele motorului Wankel in comparație cu motorul cu ardere internă

cu piston, sunt compactitatea și vibrațiile mai reduse. Dezavantajele acestui motor sunt randamentul mai mic, ceea ce duce la un

consum de combustibil mai mare pentru aceeași putere furnizată, emisia sporită de poluați, ceea ce duce la necesitatea instalațiilor de denoxare mai complexe și uzinarea și întreținerea pretențioase, deci mai scumpe.

Motorul Wankel - constructori Primul motor Wankel a apărut însă destul de târziu în 1957 mai exact,

experimentele sale fiind îngreunate de război. La acea vreme Wankel lucra în cadrul companiei germane NSU Motorenwerk, care producea motociclete. După ce primul motor a fost prezentat mai mult de 100 companii s-au arătat interesate de achiziţia acestui tip de motor. Mazda a fost prima companiei important care a preluat acest motor şi au înfiinţat chiar un departament dedicat pentru dezvoltarea acestui motor.

Astfel în 1967 a apărut Mazda Cosmo primul astfel de automobil cu un motor Wankel cu două rotoare. Acest coupe a fost la acea vreme un succes şi ulterior Mazda a pus motoare rotative pe mai multe modele. Motorul Wankel a fost însă preluat şi de alţi constructori, dintre care amintim Daimler-Benz, Alfa Romeo, Rolls Royce, Porsche, General Motors, Suzuki şi Toyota. Deşi era mai compact, mai uşor şi necesita mai puţine reparatţii decât un motor normal, propulsorul Wankel şi-a pierdut din popularitate în anii 1990, datorită consumului mare. Inventatorul său nu a apucat însă să vadă asta decedând în 1988.

Motorul Kauertz This is a fine example of the scissors or pursuing-piston type of rotary

engine, which has resurfaced many times. The primary vane or piston rotates at a steady speed, while the secondary vane rotates at a varying speed, opening and closing the spaces between them. This shows how the gear and crank mechanism moves one vane with respect to another as the whole assembly rotates. I think the central sun gear is fixed to the casing.

Motorul Revetec The REVETEC Engine design consists of two counter-rotating “trilobate�?

(three lobed) cams geared together, so both cams contribute to forward motion. Two bearings run along the profile of both cams (four bearings in all) and stay in contact with the cams at all times. The bearings are mounted on the underside of the two inter-connected pistons, which maintain the desired clearance throughout the stroke. The two cams rotate and raise the piston with a scissor-like action to the bearings. Once at the top of the stroke the air/fuel mixture is fired. The expanded gas then forces the bearings down the ramps of the cams spreading them apart ending the stroke. The point of maximum mechanical advantage or transfer is around 10deg ATDC (the piston moving approximately 5% of its travel) making the most of the high cylinder pressure. This compares to a conventional engine that reaches maximum mechanical advantage around 40deg ATDC. (after the piston has moved through 40% of its travel, losing valuable cylinder pressure). The effective cranking distance is determined by the length from the point of bearing contact to the centre of the output shaft (NOT the stroke). The dual bearings contact the two cams in the opposite side which cancels the side forces out. The piston assembly does not experience any side force which will reduce wear and lubrication requirements at the cylinder contact. This also reduces piston shock to a negligible amount making ceramic technology suitable. One module which comprises of a minimum of five moving components, produces six power strokes per revolution. Increasing the number of lobes on each cam to five produces ten power strokes without increasing the number of components.

Motorul Revetec

Motorul Webb This elegant drawing shows what is believed to be the first

proposal for a rotary internal-combustion engine. The combustion gases enter through the central port A, passing through stationary valve B via ports C, D, E and thus into the passages F, G in the rotating piston H, and then expanding further into the volumes I, J and K formed between the rotating piston and the swivelling "buttresses" L, M and N. At the end of expansion the gases left through exhaust ports O, P and Q, which appear to be covered by movable flaps; it is not clear how these were actuated- presumably by some sort of cam mechanism. The swivelling buttresses were held in position against the piston by external weights, which would seem to rule out all but the slowest rotational speeds. The piston goes round in a clockwise direction. In the diagram buttresses L and N are making a line "seal" against the piston, which makes leakage inevitable. Ask Felix Wankel.

Motorul Webb