US2506142A - Two-stroke multicylinder engine - Google Patents

Description

May 2, 195 0 M. ECHARD TWO-STROKE MULTICYLINDER ENGINE Filed July 10, 1945 2 Sheets-Sheet l j /wca ELY/MED.

xiv/Q0 #64 2 Sheets-Sheet 2 I Filed July 10, 1945 Q Maeta fax/0E0.

I ting is carried out with maximum Patented May 2, 1950 'UNITED STATES PATENT orrics TWO-STROKE MULTICYLINDER ENGINE Marcel Echard, Neuilly-sur-Seine, France Application July 10,1945, Serial No. 604,111

"In France July 3, 1944 Section 1, Public Law 690, August a, 1946 Patent expires July 3, 1964 planes; this however does not exclude the possibilitie's of all other applications for which it is suitable. r

The essential qualities looked for in an airplane engine are: a low specific weight, an extreme simplicity and reliability combined with the possibility of a good streamlined cowl; in addition, a highly uniform torque and moving parts 'with an excellent balance are desired and so is-ga reduction of the fuel consumption to a minimum. Generally in aircraft engines such advantageous properties are obtained to a more or less greatextent at the expense of mechanical comp1ications involving difllcult and costly "machining methods.

In the engine according to this invention the desired qualities are obtained by new arrangements'and combinations of some of the parts and means with a view to developing a multicylinder engine type which operates on the two-stroke cycle principla' This cycle gives a high power-weight ratio and makes it possible to dispense with a great many delicate parts liable to get out of order, wear or break. In particular, in the four-stroke engine,

the provision of valves sets a limitation on one' two-stroke cycle, this engine, which belongs to the so-called radial type, operates on the uniform principle by means of twin cylinders controlling the intake and the exhaust respectively, one head being common to both of the said parallel cylinders according to a known principle.

.This arrangement, in combination with theangular displacement through a ,small extent of the crank pin in each group of intake and exhaust cylinders respectively allows obtaining a phase difference between the scavenging of the burnt gases and the filling with new gases at the desired relative pressure which depends on the operation of the loading and scavenging air-compressor to be dealt with hereafter. Carburetefliciency by means of a pump.

The air-compressor is arranged co-axially with the main driving shaft in front of that cylinder z group, which controls the intake and is nearest th propeller.

Since the compressor is rotated in the same direction as the driving shaft through the medium of a gearing, its speed relatively to said shaft is very low or null depending on the ratio of the gearing.

As a matter of fact, the rotor of the compressor rotates at a speed, which depends on the gear ratio of said gearing. By a suitable selection of the gears, it is possible to give the compressor a speed of rotation which is but little different from that of the shaft or even a speed equal to that of said shaft. As the compressor and the shaft rotate in the same direction, the consequence is that their relative speed is low or even equal to zero.-

This involves unquestionable mechanical'advantages as to the wear and life of the'intermediate elements; the engine shaft also serves as the axle of the compressor vanes, which allows doing away with said part and saving as nine weight.

The burnt gases are taken away through a two-channel annular collector which is so ar-' ranged that in a six-cylinder bank or row the three even cylinders shall discharge into the one channel and the three odd cylinders shall discharge into the other.

avoided, and a possible dephasing' of the acousti"-' cal impulses provides a reduction in the noiseof the exhaust. a

As a result of the described combination of the characteristics, locations andarrangements ot the various parts, the overall dimensions and es pecially the front-section (maximum section) are decreased, and the ordering of the various ele-" ments lengthwise of the engine allows providing the latter with a streamlined cowl with the least possible drag. Said cowl possesses as correctanoutline as the designer may desire.

At the same time the weight of the whole-"is the num'-" Overpressures arising from interactions between the cylinders are thus;

An embodiment is shown in the appended dl'fiw f nimatlcal illustration of" cut connectingthe com:-

fitted; 5 is the ring-shaped twin-channel ex-r haust manifold, 6 the back casing in which mag-' netos, pumps, dynamos and likeeaccessory tap-.- paratus are enclosed.

Rigidly secured on the driving shaft I as shown in Fig. 2 is the pinion 8 which, meshes iwithza pinion 9 rigid with an additional pinion I ll; Pinions 9 and ID are rotatable abouta common axis; said pinion meshes with a sunwheeljli rigid with a rotor 32 constituted by a cylindrical member forming a rotor adapted to rotate eccene trically with reference to. the driving shaft 1.

Names: l2 rotate-freelyround thedrivi-ng shaft 1 I as shown more particularly in Fig." The cylindrical rotor=3z :isi provided-withlongitudinal slots: the. walls -of which-assume-a cylindrical shape; eachslot .holding.;;rotatablytwo semi-cy- 1indrical =rods ,33. Between the flat surfacesaof the semi-cylindrical rods 33 is formed a passage fontherfreez-sliding pfethervanes I 2;. The-roto1a32 drives etherblades -12 .into ..-rotation throughethe agency of r1. the; semi-cylindrical. rods 33. The spacing? between'etwo successive blades -.l 2 -may bewariables Thewrotational speed .ofTpinion-i I l and conse-- quentlygthe :feedand. pressure of a-the. compressorcanwbezaltered -easiiy by;replacing and H or 8 .andwB -by1 :-two pinionshaving the. same distance between centers but a greater or less number,- ofteethrthan the replaced pinions.

. Ohrthe other hand .the'irotor. of: the compressor- 32. is -,-driven-by theapiniont carried-by the crankshaft and by;the-pinions.-9, l0 and -I I it rotates (Fig;;.3): in the samedirection as :saidshait and'- at the same speed as the latter if the ratio rho-- tweenstheflgea-rswis suitably; chosen. This speed may. howeverqbe modified. and then. the speed .of then-rotor may sbecomepositive or negative-with reference toxthecrank'eshaft; As the :2 1'0130113. drives -the compressor blades through thetzagencyof; the semi-cylindricaL rods 33:.randras said :bl-a-desiarefreely mounted on the crankshaft whicl'rserves-onlyas a support therefor,--tlie;zdisplacement; of; the: semi-cylindrical-rods which hold the blades fast with reference'toathe crankshaft-islimited ,llflithe casezwhere --.the rotor and dice crankshaft-rotate. at. the same -speed to am; oscillating; -re'ciprocating;; movement.

jviewythe two :corjnp anion scylinders: i %and .16 have a commonz head;: at -the;;moment when: piston" l l v in IS beg-ins to;close-the intakeportthe-piston l-flr-a-in' .cylin'der. 16- has almost: closed. the exhaust ports. As thezintakeiport fist-being :closedsithei comp tessorzcdmpletesa the :filling of. -.cylindersral 5 ands! 6 inrelationmith the. iworkingz plfessure for.

which said compressor. isdesigned.

In the case of a delayed mechanical carburetting, i. e. one that takes place following the intake of a given volume of air, the scavenging of the burnt gases is completed before the piston 18 has closed the exhaust port 19 which leads into the exhaust manifold 20.. Thelatter collects the burnt gases from half the number zof cylinders, namely, every other one.

The dephasing in the closure of the ports in cylinders l5 and I6 is brought about by the angularydisplacement of the related crank pins 2! and 22, crank pin 2| for instance being at its lower dead centre while crank pin 22 is already beyondthe same inthe direction of rotation.

Aby-pass arrangement allows providing for a direct. return between the delivery and the suctioncndsof the compressor so as to reduce automatically the output of said compressor into the engine when the latter is idling.

Visible at 23 (Fig. 3) is a region, in the delivery manifold of the compressor, which can be. -set into communication through theby-passvalve 24--with+the space in which suctiomtakes place.

Saidvalve-is actuated by a lever. 23 connected with a flap valve 21 (or possibly a carburetor throttle valve) by lever ZE-and link 29n This gearas a whole. is actuatedin turn by the control rod- 39.- connected with'thelhand-lever operated by the pilot or the manln charge oftheengine.-...

It .isalways possible where necessary vtov in-v corporate an altimetricv correcting device to, the

system at any desired point. thereof.

The leverage .29-30 .is. designed and '28-may provide .for the opening of .the bye pass valve zdsimultaneously with the closingpf.

the flap or throttle valve 2'! inserted in the.suc-.. tion. pipe, of ..the :compressor and reversely.

The compressor may. .be .fed. by ;a carburetor. in. which. case-.thefiap valve .21 is constituted by. a carburetor .throttle valve of,the.type.generally used in such cases,

When the flap valve 2'! is closedpartly, the.

suction, end of. the compressor while the engine. cylinders are fed to a gradually reduced extent. 1

Thetype of. engine which. is the subject-matter of. this. invention lends itself most advantageous- 1y .to the provision of a mechanical carburettin'g by means, of fuel pumps, whether thefuel be fed at high pressure directly into the" head or be injected at low pressure.

' In the latterevent the low-pressure injector, anclatomizer. 3 is located between two intakeportsfor the purpose of conferring homogeneousness' to the mixture; Besides, no counterpressure is exerted at that point upon the *in-' je'cto r by the compression or explosion'pressures developed in thecyliridrs since in theascending strok'e of" piston I! the latter covers the-iri- J'ector 31' at the same tirne as the-intake portsand uncovers'sit 1m its" descending stroke: onlyli: after the exhausttiis openeds" This; arrangements is:azimostaimportantfone since it; makes it possi'a ble ato a do; away :-inthe; x-inj ectorv and atomizer 1 with cut-off needle or like valves which 1 are very a easilyvdamageableby reason oftheir-small-size and'of thehighspeedsattained thereby in highly rated engines. Z It is only necessary accurately to .1ensuresthat: the esarne-shall .take

place: into: the, cylinders; subsequent. the.

im. a manner. such thattherelative positioning-0fthe leversIE to time theefuelt injection.

scavenging by pure air which thoroughly drives out the waste gases while providing for an efficient cooling from the inside. On the other hand, the exhaust, when the fuel is being injected, must be sufficiently cut off, as a. result of the dephasing, to ensure that even the smallest amount of fuel can not get into the exhaust manifold without having developed useful power.

The injection of fuel into the cylinder is performed at the end of the period of admission of air into th cylinder. The amount of air admitted into each cylinder may be superabundant, in other words the volume of air admitted may be higher than the cylinder charge; the excess amount of gases is exhausted and thus cooperates in the cooling of the inside of the cylinder.

The exhaust opening is partly closed when the injection begins and is entirely closed at the end of the injection stroke.

What I claim as my invention and desire to secure by Letters Patent is:

In an internal combustion aircraft engine having uniflow paired cylinders, a crank shaft for the cylinders and a drive shaft connected to and extending outwardly from the crank shaft, the improvement which comprises a volumetric compressor having a housing, a manifold communicating with the discharge of said compressor positioned within said housing and having ports communicating with the cylinders, said compressor housing being mounted to surround the drive shaft and extending substantially co-axially therewith, said compressor having rotatable vanes, said vanes being journalled directly on said drive shaft, a rotor surrounding said drive shaft and mounted eccentrically thereof to rotate said vanes on said drive shaft, and gearing between said drive shaft and said rotor to rotate said rotor at substantially the same speed and inthe same direction as said drive shaft, said compressor functioning as the supercharger for the uniflow paired cylinders of the internal combustion aircraft engine.

MARCEL ECHARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,012,440 Reichhelm Dec. 19, 1911 1,350,159 Johnson Aug. 1'7, 1920 1,607,383 A-urand Nov. 16, 1926 1,811,625 Greening et al. June 23, 1931 1,815,868 Schenk July 21, 1931 1,882,448 Roche Oct. 11 1932 1,963,423 Shoemaker June 19, 1934 1,999,374 Pavlecka Apr. 30, 1935 2,133,578 Schjolin Oct. 18, 1938 2,159,209 Hazen May 23, 1939 2,283,694 Perrine May 19, 1942 2,311,936 Elfes et a1. Feb. 23, 1943 FOREIGN PATENTS Number Country Date 375,668 Great Britain June 30, 1932 83,945 Sweden July 23, 1935

Images