US2624171A - Construction of exhaust passages of internal-combustion engines - Google Patents

Description

Jan. 6, 1953 P. KOLLSMA N CONSTRUCTION OF EXHAUST PASSAGES OF INTERNAL-COMBUSTION ENGINES Filed July 10, 1946 3 Sheets-Sheet 2 TOP CENTER VALVE 3| cl. as

VALV E 47 m" BOTTOM CENTER INVENTOR PAUL KOLLSMAN aLZLIF LM-M 4. ATTORNEY Jan. 6, 1953 P. KOLLSMAN CONSTRUCTION EXHAUST SAGES OF INTERNAL- BUSTION INES Filed July 10, 1946 3 Sheets-Sheet 5 5W5 15 .JLf

INVENTOR PAUL KOLLSMAN M M M I; ATTCRNEY Patented Jan. 6, 1 953 UNITED STATES iPATENT OFFICE GONSTR-UGTION F EXHAUST PASSAGES' or- INTERNAL-COMBUSTIONENGINES3 Paul Kollsman, NewY-ork, N. Y. ApplicationJulylfl, 1946, Serial ,No. 6825664 4 Claims. (01. (SO-13) This invention provides; a method of,v and means for utilizing: the. energy of the. exhaust gases of internal combustion enginesv of the reciprocating type, and has particular application to aircraft engines.

According to the invention the. flow of combustion gases from the respective. combustion chambers or cylinders of aninternalc'ombustion engine is separated intoa flow of high velocityv and relatively high pressure for. conversioninto motive power and a separateflow of' relatively low velocity and lowipressure of the remainder of the gases leaving the combustionchamber. The high pressure flow of gas maybe employed: to produce reactive thrust'by discharge of the gas through an appropriate: reaction nozzle; The high pressure flow may also-be;used-: .to'drive aturbine rotor, for example the rotor ofa compresser.

According to the invention each combustion chamber, or cylinder, is provided with-two separate discharge or exhaust passages, each passage being controlled bya separate exhaust valve. One of the passages is of'relatively narrow cross section, preferably'narrowerthan'the pas-- sage provided by the respective exhaust valve when thevalve is open. By such proportioning of the exhaust passage a sudden'an'd substantial pressure drop at the valveand a-corresponding energy loss is prevented. Atpoints-beyond the exhaust valve" the passage may diverge, gradually increase in: cross section, most advantageous-increase in velocity of the expanding high pressure flow ofgas. The :passage may lead to a reactionnozzleforproducing a reactive thrust, or may lead to a'turbinenozzle for discharging the high velocity flow of combustion gas against the vanes or blades of a turbine rotor.

The second discharge passage is ofsubstantially larger cross section and serves'to remove substantially all of the'remainder ofthei cornbustion gases notflowing through the firstnamed passage to theatmosphere-or other point of combustion gas disposal.

The valves controlling adini-ssionof combustion gases to the first high-Velocity passa'ge and the second law velocity passage are operated in timed relationship with respect tothe movement of the pistonof the respective combustionchamber, and in suchmanner ,as 110, cause discharge f a p rtion f h o b tion asesuder hi h pressure through the high velocity passage, while the second low velocitypassage is-= sti 1 l,c-losed. After the peakpressure has been spent by I discharge of "a now of gas of'liigh velocity through to provide for a' 2: the highvelocity passage, which flow is converted into motivepower as hereinbeiore mentioned, the secondexhaust valve opens and permits removal of substantially allo'f the remainingcom bustion gasesfrornf the; combustion chamber through alpassa gej of low resistance. The first discharge valve controlling the high-velocity passage may be causedto openwhile the piston is still on its downwardcombustionstrohe; for example approximately 59to before bottom center of the respectfve crank, and the second exhaustvalve controlling-the second discharge p ssa e m nen'ap r at v 0 2 fore bottom center;

While thetiming' of the opening of the two valves is important and should occur successively as hereinbefore described, the two valves may close substantially simultaneously, for example when the respective crank-reaches top center.

The objects, features,,and advantages of this invention will appear more fully from the detailed description which follows accompanied by drawings showing for the purposeof illustration devices for practicing" the invention.

The inventionalso consists in certain new and original features of construction and combination of parts hereinafter set forth and claimed;

Although the characteristic features ofthe invention which are believed" to be novel will be particularly pointed out" in the'claims appended hereto, the invention itself; its objects, and advantages, and the manner in which it maybe carriedout may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part of it in which,

Figure 1 .is a side elevation, of a cylinder pist'on'and crank combustion engine;

Figure 2 is a partial'view of a high velocity exhaust passage leading from an engine of the type shown in Figure lto a turbine rotor;

Figure 3 is a detailed'view"illustrating, on an enlarged scale, the cams for operating the two exhaust valves of the engine: shown in Fig. 1;

Figured is a diagramillustrating the timing of the two vexhaus'tvaliles;

Figure 5"is' a view of a modifiedforin of high velocity exhaust passage;

Figure '6 is asectional view through a high velocity exhaustpa's'sage having divergent walls automatically. adjustable, in dependence on the pressure of' the exhaust gases flowing through thepassage;

Figure 7" is a-sectiontaken on line l-l of Figififand. i H

partly. in section, of an internal Figure 8 is a perspective view of the passage shown in Figs. 6 and '7.

In the following description and in the claims various details will be identified by specific names for convenience. The names however are intended to be as generic in their application as the art will permit. In the drawings parts of the engine not necessary for an understanding of the invention are omitted for the sake of clarity.

Like reference characters refer to like parts in the several figures of the drawings.

In the drawings accompanying, and forming part of, this specification certain specific disclosureof the invention is made for the purpose of explanation of broader aspects of the invention, but it is understood that the details may be modified in various respects without departure from the principles of this invention, and that the invention may be applied to and practiced by' other structures than the ones shown.

Referring to the drawings the engine shown in part in Figure 1 comprises a cylinder housing I! having cooling fins I 2 and a flange :3 for mounting on an engine housin (not shown).

A piston I4 is movable in the cylinder and forms with the cylinder a combustion chamber l5. The piston is pivotally attached to a connecting rod l6 by a pin [1, and the connecting rod it; engages a crank pin l8 of a crank shaft [9.

Combustible mixture is admitted into the combustion chamber l5 through an intake passage controlled by an intake valve 2|. The intake valve 2| has a stem 22 carrying a collar 23 against which a valve spring 24 bears tending to maintain the intake valve closed. The intake valve 2| is operated by an intake valve lever 25 pivotally mounted at 26 and engaging with one end 27 the stem of the intake valve 2|. The other arm of the intake valve lever 25 carries a roller 28 which engages the periphery of a cam 29 on an intake cam shaft 30. The intake cam shaft 38 is coupled to the crank shaft It in conventional manner (not illustrated) to cause the cam shaft 30 to turn at half the rate of the crank shaft [9.

A first exhaust valve'3l controls the admission of combustion gas from the combustion chamber l5 to a relatively narrow discharge passage 32. The exhaust valve 3| has a stem 33 to which a collar 34 is attached. A valve spring 35 bears against the collar 34 and tends to maintain the exhaust valve 3! closed. A first exhaust valve lever 36 pivotally mounted at 31 engages with one end 33 the valve stem 33 and carries at its other end a roller 39 engaging the periphery of a first exhaust valve cam 49 on an exhaust valve cam shaft 4|.

A second exhaust valve cam 42 (Fig. l) is fixed on the same exhaust valve cam shaft 4! and engages with its periphery a roller 43 at one end of a second exhaust valve lever 44. The second exhaust valve lever is likewise pivoted on the shaft 37 and engages with its other end 45 the stem 46 of a second exhaust valve 4'! controlling admission of combustion gas into a relatively wide exhaust passage 48.

The two cams and 42 are so arranged as to cause the first exhaust valve 3| to open before the second exhaust valve 41 to permit the combustion gas of high pressure to pass through the relatively narrow first exhaust passage 32. At the time of opening of the first exhaust valve 31 the ases inside the combustion chamber l5 are at peak pressure. The as flowing through the exhaust passage 32 attains a very high velocity, up to sound velocity and even beyond the velocity of sound, depending on the shape of the passage '4 32 and the pressure drop encountered by the gas during its flow through the passage.

After the peak pressure of the combustion gases is spent the second cam 42 causes the second exhaust valve 41 to open, whereby substantially all of the remainder of the combustion gases, which now have dropped to a relatively low pressure, are permitted to escape from the combustion chamber I5 in preparation of the next suction and compression strokes of the engine.

The energy of the high pressure combustion gases may be utilized in various ways.

The gases may be used to drive the rotor of a turbine. This is, illustrated in simplified manner in Figure 2 of the drawing. The exhaust valve 3| controls the admission of combustion gases at peak pressure into a relatively narrow discharge passage 32' leading to a discharge nozzle 49 directing a jet of gas against the vanes 50 of a turbine rotor 5! on a rotor drive shaft 52. The passageis preferably narrower than the passage provided by the exh ust valve 3! when the valve is open.

A second exhaust valve (not shown) is pro vided for opening and closing a second exhaust passage or exhaust stack 48 of relatively wide cross section for the remova1 of'combustion gas still remaining in the. combustion chamber l5 after the gases of peak pressure have been removed through the first exhaust passage 32'.

A typical cam arrangement for the two exhaust valves is shown in Figure v3. The cams 4- and 42 are fixed on the same exhaust valve cam shaft 4| and move in the direction'of the arrow 53 at half the'rate'of'the engine crank shaft. The elevated portion-of the two cameras are offset so as to "cause actuation of" the exhaust valve controlling the high pressureexhaust passage before actuation of the second exhaust valve which controls the exhaust passage of large diameter. In the illustrated embodiment the cams are offset 25 whichconsidering the ratio at which the cam shaft 4| 'is' geared'to the engine crankshaft, amounts to an advance opening of the first exhaust valveove'r the second valve of 50 in terms of engine crankshaft'movement.

A typical diagram illustrating the timing of two exhaust valves of an engine embodying the invention is shown in Figure 4. in terms of crankshaft movement. According to the illustrated arrangement exhaust valve 3! opens approximately before bottom center. The exhaust valve 3! opens during the combustionstroke, at a time the piston is on its down ward movement. When the exhaust valve 3! opens the mixture in the combustion chamber of the engine was just fired by a spark plug or otherwise, is fully ignited and at high pressure forcing the piston downwardly. While the pressure is still high the first exhaust valve begins to open causing a flow of combustion gas of high pressure to pass through the first; exhaust passage at great velocity. The energy of thi ex haust gas is utilized either to produce a reactive thrust or to drive a suitable prime mover as here- 'inbefore described. Ten degrees before bottom center of the crankshaft the valve 41 opens to permit the remainder of the combustion'gases to escape. Both valves remain open throughout the upstroke of the piston and close at'top center of the crankshaft when the suction stroke of the pistonis aboutto begin. I

It is evident that the'timing of the two valves relatively to each other may be changedas well The diagram is as the opening and closing points of the valves withrespect to bottom and top center.

The exhaust passage for the high pressure gases may be made oi substantia l-ly.- uniform cross section and of considerable length to produce slugs of gas of considerable pressure whieh pa throughthe passage at highvelocity timed with the opening of the exhaust valve 3|. Asshown in Figure 5 the passage-32' isot uniform cross Section d preferabl na rower th the D sage past the. valve 31'. The purpose of making the us ass e 32" relat vel har sw i to make the pressure drop at or near the valvesmal l whereby energy losses at this point are maintained correspondingly low.

Figures 6, 7 and 8 illustrate an exhaust passage 3'2" of gradually increasing cross section to permit flow velocities to in excess of the velocity of sound. Two walls 54 and 55 of the passage 32 are adjustable in dependence on the changes in pressure of the exhaust gases flowing therethrough. Flexible blades 56 and 51 of an alloy capable of resisting high temperatures are acted upon on the inside by the pressure of the gas flowing through the passage 32" and are acted upon on the other side by the ambient pressure which may be the exhaust pressure of the turbine driven by the exhaust gas, this pressure being near atmospheric pressure. Exhaust gases flowing through the passage 32" may attain velocities in excess of the velocity of sound assuming the pressure drop of the gas is in excess of the so called critical drop. This pressure ratio is measured at the intake point where the pressure of the gas is a maximum and the velocity substantially zero and at the discharge point of the nozzle or passage 32" where the velocity is a maximum and the ressure the lowest, for example substantially atmospheric pressure. The combustion gases are discharged at high velocity against the vanes 5!! of a turbine rotor 5| to drive the same.

The invention thus provides a method of and means for utilizing a great percentage of the energy of combustion gases of internal combustion engines which is ordinarily lost or wasted. The invention can conveniently be practiced with existing engines equipped with two exhaust valves after appropriate modification of the engines to provide for actuation of the two exhaust valves one after the other and by providing separate exhaust passages for the two valves.

While the invention has been explained and illustrated by application to an engine equipped with poppet valves it may also be practiced by or applied to engines having sleeve valves. It is also applicable to engines of two cycle or two stroke type in which the piston acts as a valve member and controls appropriately located ports in the cylinder wall. Rearrangement of the ports or appropriate shaping of the edge of the piston controlling the ports manifestly produces the same results as the valve mechanism of the illustrated four cycle engine. Thus various changes, additions, onfissions, substitutions and other modifications may be made, as will occur to persons skilled in the art without departure from the spirit and the teaching of this invention.

What is claimed is:

1. In a reciprocating internal combustion engine the combination with a cylinder, of two distinct exhaust passages, namely a first high pressure passage of relatively narrow cross section, and a second low pressure and low velocity passage of a cross section larger than said first passage; a poppet valve in each of said passages;

be obtained which are.

and means for Opening in. timed sequence first the valve in the high pressure passage and there,- aiter the valve in the low pressure passage, the narrow high pressurepassagehaving a restricted portion downstream ofits valve for maintenance of back pressure and a high velocitynozzle portion downstream of said restricted; portion for conversion or pre s re secrets i i i kinetic energy, the high pressure passage upstream of the restricted portion being so, dimensioned with relation to its contro ling valve that its cross sectional area is at all pointsv less. than the valve opening considering the valvein fully openiposition, whereby turbulence losses, at the valve proper are minimized.

2. In an internal combustion engine the combination with a cylinder and a piston reciprocable therein, of, a first exhaust passage having at least one movable wall acted upon by the pressure on the interior side of the wall and by the pressure on the exterior side of said movable wall, respectively, the wall being unbiased and face to adjust its position in dependence on the difierence between said two pressures acting on the wall to increase and decrease the angle of divergence of said passage; stop means for limiting the extent to which the movable wall may be flexed to a pre-determined maximum angle of divergence of the nozzle passage toward the discharge end of the nozzle under predominant gas pressure on said interior side; a first exhaust valve for opening and closing said first passage; a second exhaust passage of larger cross section than said first passage; a second exhaust valve for opening and closing said second passage; means timed with said piston for opening first said first valve and thereafter said second valve, whereby high and low pressure fiows of combustion gases are discharged through said first and second passages, respectively; and a turbine rotor adapted to be acted upon by the gases discharged through said first passage.

3. In an internal combustion engine the combination with a cylinder and a piston reciprocable therein, of an exhaust valve; an exhaust passage extending from said exhaust valve, said exhaust passage having a portion of narrowest cross-section less than the area of passage of said exhaust valve when the valve is in fully open position, said exhaust passage further having a divergent portion including at least one adjustable wall adapted to increase and decrease by adjustment the degree of divergence of said passage portion; and means responsive to changes in pressure inside the passage for automatically adjusting said wall.

4. In an internal combustion engine the combination with a cylinder and a piston reciprocable therein, of a pair of exhaust valves, means for operating said valves in timed sequence, separate exhaust passage extending from said valves, the passage extending from one valve having a divergent portion bounded by fixed rigid walls, a flexible blade lying adjacent one of said walls, said blade being secured to said one wall at one end near the valve and being free to move at the other end remote from the valve, said blade being acted upon by the gas pressure on the interior side tending to flex the blade in a direction to increase the cross-sectional area of the nozzle if the gas pressure on the interior side is greater than the pressure on the exterior side of the blade, the rigid wall adjacent the blade limiting the extent to which the blade may be flexed to a predetermined maximum angle of divergence Garve Feb. 1940 15 7 8 bf the nozzle passage towardsrthe dischargeend Number Name Date of the flOZZlB. i 2,303,992 Frazer Dec. 1, 1942 i PAUL 2,342,262 Franz Feb. 22, 1944 REFERENCES CITED 5 FOREIGN PATENTS Th 1 11 f n' e r of record in the Number' Country Date file 55,5313? ate? S a e r 179,925 Great Britain May 10, 1923 1 r 1 522,935 Great'Britain July l, 1940 V UNITED STATES PATENTS 523,468 Great Britain July 15, 1940 Number Name Date 1,025,921 Muller 1 May 7, 1912 10 OTHER E E E 15 339,4 Simpson May.11, ,1920 The Internal Combustwn Engme.by D. R. 1 423 925 Thomas Sept 12, 1922 Pye, published by Clarenden Press, Great Britain, 2,051,436 Curtis Aug. 18, 1936 1931,page 1

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