US2124542A

US2124542A - Rotary engine

Info

Publication number: US2124542A
Application number: US697324A
Authority: US
Inventors: Chisholm William
Original assignee: Individual
Current assignee: Individual
Priority date: 1933-11-09
Filing date: 1933-11-09
Publication date: 1938-07-26
Anticipated expiration: 1955-07-26

Description

w. CHISHOLM Y ROTARY ENGINE Filed Nov.l 9; 1953 July; 26,1938. 2,124,542

2 Sheets-Sheet l WM. EHJHaLM', .ZNVEN Tan,

Patented July .26,` .19.38 I

UNITED STATES PATENT OFFICE 10 Claims.

The present invention relates to rotary engines,

and particularly to the non-pulsation type of engine, and to this end certain combinations and arrangements of parts are used to produce a continually ring enginewhich in turn produces a very smoothly operating motor with practically no vibrations during any part of its revolution.

The engine in hand is provided with a rotor having outwardly extending reciprocating vanes therein and a similarly constructed feed-valve connected with the main chamber of the engine for supplying gas to same; also certain novel means for supplying lubrication to the engine which will be described herein. Other advantages, and the nature and construction of the engine will be further described below as the specication proceeds.

In the accompanying drawings forming a part of this specication I have shown a complete embodiment of the invention adapted to accomplish 'the purpose in hand, in which:

Figure 1 is a transverse section through the rotary engine, taken on line I-I of Figure 2.

Figure 2 is a longitudinal section of the engine taken on line 2 2 of Figure l. i

Figure 3 visa side elevation of the engine partly in section taken' from the right as seen in Figure l; g

Figure 4 is a longitudinal side elevation of the rotary valve used in my invention.

Figure 5 is an end view of Figure 4, taken; from in section, illustrating the method of keying the rotor of the valve to its shaft, similar to fthat` shown in Figure 3.

Figure 11 is an enlarged vertical partial section through the rotary transfer valvev and its casing, taken on line I |--I I of Figure 1.

In the drawings, thel numeral I indicates a substantially cylindrical casing which forms the body of the rotary engine, having an enlarged portion 2a, also in substantially cylindrical form; the casing I encloses the main rotor 2 of the engine and the rotary transfer valve 3|.

The casing I has a chamber 4 of unsymmetrical outline and is provided with a gas inlet 5 and an exhaust outlet port 3; The rotor 2 is of sub'- stantially cylindrical shape and of solid material except for a series ofpreferably

radial slots

1, 8, 9, 18, 19, 80, 8I,`82 in which a series of blades I0, 53, I2, 83, 84, 85, 22 slidably operate.

The rotor 2 has a central shaft I3, which is 83, 84, 85, and 22 are of :dat solid material' and are adapted to reciprocate in the

slots

1, 8, 9, 18. 19, 88, 8|, and 82, respectively, riding against, at their inner edges, springs such as I8 or I9, and on their outer ends 28, the edges of each of said blades are slightly bevelled at 13, as shown in Fig. 1 for a purpose described below.

It will be seen from Fig. 1 that the compression spring I9 forces the vane or blade II outwardly in a radial direction and when one of said blades are in their outermost position as II, a portion of their lower edges 2| still remains mounted in the body of the rotor 2.

When the vanes are rotated to a position illustrated by |12, or 22, the blade is forced inwardly and compresses the vsprings such as I8 or 82 in their recesses. Thus the outer edge of any 4oi" the -blades is always held in close contact with the irregular inner Wall of the chamberv 4, and the outer edges 20 of each of the blades being slightly bevelled, in each instance form a definite contact with the wall of the fchamber 4 at all times during the revolution of the rotor. In order to make each of the vanes follow a'definite path Within the chamber '4 as the rotor 2 isrevolving,

means are adoptedat '23, 24, 25,- 26, 21,29, to depress the vanes against the springs such as 1, or 8, duringcertain period of the revolution vof the rotor2. This means is at 23, 25, 21, 29,A made by the inner face of the chamber 4 in the casing, while at 24 and 28 a guiding ridge is formed on, each of the opposed rend walls I6and I1 of the engine, as clearly illustrated in Figs. 1 and 2 of the drawings. Y

`It willbe noted that as the rotor 2 revolves the various vanessuch as 22, |0,II, |2all follow a deiinite path of travelwith respect to .their outer ends, as is at once understood.

In the casing I is also rotatably mounted onits axis 30 a rotary transfer valve 3| which is keyed at 5S to said shaft 39 in a similar manner to that mentioned with reference to the shaft I3 ofthe ing slidably mounted therein'a series ofvanes 32,

l33, 34, 35,'

Y

86, 81, 88, `89, very similar to rthose shown in the main engine chamber 4, Fig. `1. kIt will be noted that the outline of the interior of ,thevalve chamber' 36v is substantially circular and that the vanes 'such as 32,33, reciprocate in the drum'16 of the rotary valve 3I against

similar springs

14,14 to'those used in connection with .the main rotor 2. The path of travel of the outer end of the

blades

32, 33, is clearly illustrated in` Fig.`1 of the drawings. At one end of the engine, on the shafts I3 and 38 respectivelyare mounted l the

gears

31, 38 which' intermesh with each other so that' the relation between the speed of the main rotor 2 and the speed of the rotary valve vill maybe held in a desired'relation to each other. The main casing I has a removable end I1 in order to remove parts and assemble engine parts, which is held o n to they, main casing by means of Va series of bolts such as 48, 48, as is at'once understood, and'said removable lend I1 isl provided with,`

an inwardly projecting flange 4I thereon which engages into a complimentary recess 4 I' formed in the body of the casing I as clearly illustrated ,of a fuel charging passage 46'for thepurpose ofY admitting gas `from the engine chamber to the Valve chamber. There is'also a fuel v,combustion passage 41 connecting the two chambers to each the main rotor normally revolves in a clockwise other for admitting gas from the valve chamber A to :the'explosion chamber 48. In the explosion` Vchamber is located a spark plug 49 of proper design, same being mounted in the end wall I6 of the engine as. shown ings.

The outer wall vof the valve chamber 36 is connected with anl exhaust scavenging port V58, and

the wall of said chamber is preferably slopedat `5I for a purpose which will be described later.

It is evidentffrom ywhat has been said that gas admittedV throughV theA gas inlet 5 will be caught up by the blade I8 and carried along in. the portion52 of the engine chamber 4 to a point illustrated'by the vane 53, Fig. 1, and thereafterthe said gas will be pushed along through the'fuel charging passage 46 and delivered into the portion 54 ofthe valve chamber 36, from whence the blade/ 34 sweeps it inv an anti-clockvwise direction into the fuel',combustion passage 41 and back into the explosion portion 48 of the chamber 4. The gas is exploded at v.this point either byv a spark plug-49, or other"suitable' means which will be described herein, and when theengine "blade reaches'th'e position illustrated by 55,the gas willbepushed onward in a clockwise direction and eventually swept through the exhaust outlet 6. It is also seen that lany explodedgas trapped between the vanes of the rotary transfer valve 3I-will be caught` by oneof ltheblades such as 32,583, and sweptA in an anti-clockwise direc. tion out throughthe exhaust port 58 of. the valve a chamber 36. In this connection it isseen that direction; while the rotary valve normally revolves in an anti-clockwise direction, and as they areV geared to each other by means of the gears v31 and 38 this is readily accomplished and their enginerotor 2. y The valve 3I'is yprovided with a drum 16 of substantially cylindrical shape hav- -gas through the port 58.

may be provided with a sen in Figs. l, 3 and 6.of the` draw-v proportionate speed of revolution properly adjusted as required. y i y 'Ihe rotary valve 3l is provided with

recesses

51, 51 in which are

springs

14, 14,-similar to those used in connection with the main rotor 2, and

f the axis 38 of the rotor is suitablymiounted in the 'bearings at 58, 58 of the valve casing 2a.

It is seen .that as rotaryy valve 3| rotates, the cutaway portion'5l facilitates the exhaust `In Figure2 it may be seen that the solid portion 59 of the rotor 2 projects at each end at 68,68 into the end walls I6 and I1 respectively and provides a sealagainst the escape of any gas ywhich may be caught at the bottom 6I of the recesses such as 1, 8, of the rotor blades such as I8,- II. Each of the bladesvI8, II, is provided with plates on each end thereof as shownin Figs. l8' and,9 of the drawings at 6262. These plates act substantially like a piston ring in an engine to prevent the gas passing from one section 25 of the chamber 4 toany other sectionor portion,

such as 52. The plate 62 is 'of rectangular cross section and is set in a recess 63 of the blades such' asY I8, II, and

springs

64, 64 set in two recesses.

64', 64' also formed in said blades, at right angles to recess 63', tend to keep theplate .or bar 62 against the -surface 65 of the end walls I6 and I1 of the engine. The said plates are held in place g vertically as seen in Fig'. 9, as the4 blade I8 re- 'ciprocates in the slot 1, by means I.of

extensions

66, 66 formed on the blade I8, as is ,at once Iunder@A stood. It will be understood that what has beenv just described with reference to Figs. 8 and. 9' is also adapted to be used in connection with the rotor'` 3I of the rotary valve as illustrated in Figure 11l of the drawings.- In Figure 1l it is seen that the solid portion 16 of the-rotor 3I projects at 68',

into the end wall i6 of the engine, and providesfaoV caught at the. bottom 6I' of the recesses which a seal against the escape ci any gas which may be carry the rotor blades'such as 86 or 89. Each of v ysaid rotor blades is provided with a plate 62 on each end thereof, as shown inFigure 11 of the drawings. These plates are like the plate 62, of

Figure 9, and prevent gas passing from one valve ngular cross-section, eblades 86, 89 etc., o-recesses 64b, 64b

{Ihe plate 6E isv and is set in a r fhehplate 62` against all/I6 :of the casing. in place' vertically as seen in Figure 11,' as the blade 86 reciprocates in re placed atright .chamber 54 (Figure l) to adjoining chambers l such as 11. l

its slot, by means of extensions 66', 66 formed on' the blades 86, as is at once understoodxs, The lubricating system used with' the engine in hand comprises a supply tube for oil 61, which enters through the end of theaxle I 3-in the main rotor, andpasses through the central `tube `68 whichr runs longitudinally through said axle.v

From said tube the oil passes bymeans of sepathus admitting oil to the bottom 6I of the said blade recesses, thence along the sides of the said blades I8, II eten/into the chamber 4 of the engine, and tothe 4workingsurfaces 28, 28 ofthe blades,`and providing 'sumcient lubrication for the blades at their pointsy ofl contact withI th inner `periphery 'of the chamber 4 of the engine. `With reference to the amount of oil suiilcient to run the' engine, same is controlled by the ad- .

rate ducts

69, 69 to the recesses such as1, 8, 9,

mission of a predetermined quantity through the tube 31 as is found sumcient to provide the proper lubrication for the engine. The rotary valve f is lubricated in a similar fashion, through the tube 13 and ducts 51 to each of the blades such as 33, 34, to that described in connection with the rotary partsof the engine. as is at once understood.

'I'he operation of the present non-pulsation engine is as follows:

The mixed gas and air is admitted through ,the gas inlet into the portion 1I of the engine chamber 4 between the blades I3 and Il. As the rotor 2 revolves, the blade I0 is forced outwardly by the spring 1 against the outstanding ribs 24 formed on each of the ends I3, l1 of the engine; so that the gas which has entered the,

portion 1I of thechamber is confined between the said blades. It will be noted that as the blade' or vane Il advances, it produces a certain suction and tends to pull the gas from the gas inlet 5 into the engine. As the vane Il reaches' a position such as illustrated by vane 53, the portion 1l of the chamber 4 takes the form illustrated by the portion 52 of said -chamber and be- .gins to compress the charge of gas and air and whensaid charge is carried forward i until the vane reaches the position illustrated by vane I2, the charge is still further reduced in volume as in the portion 25a. In the meantime, however, r

the charge has found an exit through the passage 43 into the portion 54.of.the valve chamber 33. The compressed gas is then held between the

vanes

33 and 34 of the rotary valve 3|, which is operating in an anticlockwise direction, until the charge of gas and air reaches a point illustrated by

vanes

32 and 33. and thence gains admission through the passage 41 into the explosion chamber of the engine. The spark plug 49 then explodes the charge at'this point of its travel. l y

Thevane Il I then occupies the position of vane 55 and the force of the explosion pushes the vane forward in a clockwise direction and the portion of the charge which has been within the portion Y ofthe valve illustrated between

vanes

32 and 33, is carried forward in said valve chamber to the exhaust port 53-and is discharged therefrom. In this connection attention is drawn to the construction of the feed valve, the outer-circumference 15 of the drum 13 of the rotor 3| being placed in close contact with the inner peripheryof the valve chamber 35 for a portion of its length, so

that all burned gas is vcompletely driven out of the valve as each individual chamber between the valve vanes passes the exhaust port 53. and

the flared mouth 3i of the latter aids in' quick expulsion of the burned gas from-the valve. After the burned gas is expelled it is evident that as the valve rotor moves forward in 'an anticloclrwise direction. and the valve vanes begin to project from their recesses in the valve drumjl, a cham. ber', like 11, is formed in which there is a substantial vacuum. This vacuum is of particularuse when the vanes are in the position illustrated by vanes 33 and '34, as a suction effect is produced inthe individual chambers, which quickly draws in the fuel through passage 43 into said chambers. This arrangement of parts prevents all back pressure in the valve, and is an important factor both as to power obtained, and smooth operation of the engine; as is vreadily understood. It will be further seen. as there .is no burned gas in the individual chambers,.the proper proportion of fuel gas and air is not disturbed, ,and a good explosive v mixture delivered to the explosiony chamber.

Theexpand'ed charge in the explosion chamv ber 43 next passes along through the chamber 4 to the exhaust outlet 6 and as the vane Il takes the position illustrated by 12 it is seen-that the exploded gas is completely expelled into the exhaust outlet, when the vane reaches the position illustrated by'vane 22. t

It will be seen that there is always a compressed charge of gas and air in the passage 46 ready to be taken up by the vanes of the rotary valve and delivered into the explosion chamber 43.4 Said` able pulsation in its operation. VThis type of enygine may be called a non-pulsating engine.

It is of course noted that the

gears

31 and 33 which are on the respective shafts I3 and 33 are intermeshed, so that the rotation of the engine rotates' the rotary transfer valve, and the respective speeds at which the engine and ther rotary valve are required to be driven in accordance with vthe respective size of the engine and valve, can

be readily attained by changing the .relative size of the

gears

31 and 38 as is readily understood.

As explained in the specification above, the engine and valve may be water-cooled inany manner desired, such as that described, and the engine may be lubricated by any system'of lubrication besides that described herein.

Attention isdrawn to the fact that, while the sparkplug 43 normally Aexplodes the charge of gas in the explosion chamber there always remains in the passage 41 a certain quantity of burning gas at a high temperature, and that this burning gas may be used to ignite a fresh quantity of un-burned gas if required. It will be noted that when an explosion takes place in the explosion chamber 43, the clockwise operation of the engine rotor and vane l2 4will sweep forward the -burned gas into the exhaust port in the chamber 4. The same is true with reference to the operation Vof the valve chamber contained between

vanes

32, and 33, the gas contained between said vanes being swept forward by the rotation of the rotor tothe outlet 50. When a fresh supply of gas is brought forward by the movement of the

vanes

34 and 33 of the valve, this may be ignited by the heated gas which h as remained in the .passage 41 between the valve and the engine chambers so that when the engine is in full operationv the sparkplug can be disconnected if desired. the succeeding charges of gas being ignitedv 'by the heated burning gas in the passage 41.

This is believed to provide quite an important fea- A ture in my invention since after the engine has Vbeen started and thoroughly warmed up by the use of the sparkplug it is optional whether the in operation thereafter. From the above description it is seen that I havev latter is used or not in order to keep the engine produced an engine that is practically non-v pulsative in its rhythmic operation.

I claim: Y .1. In an engine, a casing having an engine rotor chamberand a rotary valve chamber therein,

I an inlet port in the'latter, an engine rotor, and a rotary valve provided with a drum, each mounted in oneof the'casing chambers, a fuel .charging passage and a combustion passage connecting the engine and valve chambers, said fuel charging passage being connected to the valve inlet` 1 passage vindividual explosion chambers therebetween, a number of individual lvalve chambers formed by the vanes of the rotary valve and the casing, a scavenging port in (the valve yadjacent to the valve drum and located in a position with respect to the combustion passage,I the charging passage and the drum ofthe valve, so as to permit lthe burned gases of the individual valve chambers to be completely expelled therefrom, and means for reducing thesize of the valve chambers to zero thus excluding burned gases from said chambers before they are recharged' with fuel.

2, In an engine, a casing having an engine rotorv chamber and a rotary valve chamber having `an inlet and exhaust port therein, van engine rotor and a rotary valve mounted in said'chambers respectively.l a fuel charging passage connectingthe engine chambers and the valve inlet port. a

combustion passage connecting the engine and' valve chambers, a plurality of vanes mounted in vthe engine, rotor, a plurality of vanes mounted in the rotary valve equal'to atleast halfthe number of those in thel engine rotor,` said enginev and valve vanes forming with the casing and the fuel combustion passage explosion chambers therebetween, a'number of -individual valve chaxrlbersMVV formedby the vanes of the `rotary` valve and thecasing, a number ofindwardly bossed ribs on 'the ends of the casing adapted toform guiding ridges'for the engine and rotary v`alve vanes, and

meansfor completely expelling burned g'as from Vform guiding ridges for they vanes, a fuel passage e each, individual valve chamber, and means for Areducing the sizeof each valve chamber to zero 'fory the purpose of excluding burned gases from said chambers before being recharged with fuel.

3. In a. rotary engine having fuel charging and explosion means therein, a casing having'a rotary valve chamber and an engine chamber formed therein, valve inlet and exhaust ports in that part of the-casingforming .the rotary valve chamber, an engine chamber `exhaust port in the casing for expellingtlie major portion of the burned gases I from the engine, a rotary transfer valve compris,-

ing a drum, with a portion of its periphery 'in contact with the ,inner wall of the casing, eccentrically mounted in the rotary valve chamber, a

lplurality Vof spring-actuated .vanes slidably,

mounted inthe rotary valve drum, forming with the, walls. of the 'casing individual chambers ;-.,therebetween, and adapted to expel the burned.

gases from said chambers through the first-meny tioned exhaust'port, and a `number .of inwardly cluding, burned' gases therefrom before the said' bossed ribs inthe valve' chamber and formed on the end sof thecasing, adaptedto form guiding ridges for the vanes, the aforesaid rotary valve drum beingzadaptedl to coact with therinner wall of the casing, the bossed ribs, and the springactuated vanes to reduce the size of 'the individual '-'valve chambers to zero, for the purpose of exvalve `chambers are recharged vwith fuel.

4. In a iiotaryengine having a fuel charging andexplosi'n means therein, a casing having a rotary ,valve chamber and an enginelchamber magma i chambers are recharged with fuel.

` .i formed therein, a valve chamber exhaust port, a valve fuel inlet portand a, combustion portI formed in the casing, an engine chamber exhaust port in the casingfor expelling the-major portion ofthe burned gases from the engine, :a rotaryv 5 transfer valve comprising a drum, with a portion .of its periphery in contact'with the inner wallof -the casing, eccentrically mounted in the rotary valve chamber, a 'plurality of spring-,actuated vanes slidably'mountedin the rotary valve drum, 10

forming with the walls of the casing individual chambers therebetween, and adapted to expel the burned gases from said chambers through the first-mentionedr exhaust port, la number of inwardly bossed ribs formed on the ends of the cas- 15v ing, adapted to form guiding ridges for the vanes, where they Dassthe mouths of they above-mentioned valve ports, the aforesaid rotary valve drum n Y being adapted to coact with the inner wall .of the casing, the bossed ribs, andthe springfactuated 20 lvanes to reduce the size of the individual valve Vchambers to zero for the purpose of excluding burned gases therefrom 'before' the Asaid Vvalve chambers are rechargedwitl fuel.

f 5, In an engine, a casing having an engine 25 rotor chamber provided with a fuel inlet, and an exhaust port, and a rotary| valve chamber vprovided with'an inlet and exhaust port therein, an engine rotor mounted in the first named. chamber, a rotary transfer valve comprising a .drum 30 with a portion of itsperiphery in contact with the inner wall of the casing,'ecentrically mounted in the rotary valve chamber, a plurality of i spring-pressed, slidably mounted -vanes in the engine rotor, a plurality of spring-pressed, `slid- V4435 connecting the engine rotor chamber and the rotary -valve chamber, a combustionpassagejoiningthe engine rotor and the'rotary valve chamj bers forming with 4the engine rotor, the vrotary Y valve, and their vanes, a combustion chamber for the engine, the aforesaid rotary valve being v adapted to coact with the innenwallof the casing, the bossed4 ribs. andthe spring-actuated vanes of the valve, to reduce the size o f the individual valve chambers tol zero for the purpose of exfl cluding burned gases therefrom, before said valve 6.In an engine, a casing yhaving an` engine rotor chamber, and a rotary valve chamber with. an inlet and exhaust port therein, an engine rotor mounted inthe first named chamber with a number of vanes mounted therein, forming with co i the casing individual engine chambers therebetween, a fuel charging passage` connecting the engine chamberV andthe valve inlet port, a fuel combustion passage ,connecting the engine and valve chambers, a rotary transfer valve compris? ing a drum,- eccentrically mounted in the valver chamber with va. portion of said drum in contact l",

withlth'e vini-n n'.periphery.oi the /valve chamber, -a pluralityof vanes mounted in the rotary; valve equal to at least hal! the number of thosein mthe engine` rotor,xforming"iwith the 4casing indi- A f vidual chambers therebetween, a number of in-l vwardly'bossed ribs-on the ends-of the casingI ,y Y

adapted to form guiding ridges,v for thefengine f and rotary valvevanes, means forcompletely expeiling burned gas from each .individual chamber of the engine and rotary valve, and reducing the size of both the engine and valve chambers to zero. v

'7. In an engine, a casing having an engine rotor chamber providedv with an inletl and exhaust-port, and a rotary valve chamber therein, an engine rotor mounted in the first named chamber, a rotary transfer valve comprising a drum eccentrically mounted in the valve chamber with a portion of said drum in contact with the inner periphery of the valve chamber, a plurality of vanes mounted in the rotary valve forming with the casing lindividual chambers therebetween, a valve fuel inlet port, a valve combustion port and a valve -exhaust port formed v in the casing walls, a fuel charging passage connecting the engine chamber, and the Valve inlet port, a fuel combustion port, and means yfor excluding burned gases from each of the valve chambers before being recharged with fuel.

8. ln an engine, having a casing, an engine' rotor chamber and a rotary valve chamber therein, inlet and exhaust ports in both chambers, an engine rotor and -a rotary valve mounted in said respective chambers, a fuel combustion passage between the two chambers, a fuel charging passage connecting the engine chamber and the valve inlet port, a number of vanes mountedl in the engine rotor, a plurality of varies mounted in the rotary valve equal to at least half the number of those in the engine rotor, said engine and valve vanes forming with the casing and the fuel combustion passage a number of. individual explosion chambers therebetween, a number of individual valve chambers formed by the rotary valve vanes and the casing, means in the valve chamberfor completely expelling any entrapped exploded gas yfrom the individual valve chambers, and for preventing'same from entering the valve chambers before the latter are recharged.`

with fuel.

9. In an engine, having a. casing, an engine rotor chamber and a rotary valve chamber therein, inlet and exhaust ports in both vchambers an engine rotor and Va rotary valve mounted in said respective chambers, afuel charging pas- 'sage" connecting the engine chamber and valve inlet port, a fuel combustion passage connecting the engine and valve chambers, a number of vanes mounted in the engine rotor, a

plurality of vanes mounted in the rotaryvalve equal to at least half the number of those in the engine rotor, said engine and valve vanes respectively forming with the casing a'n'umber'.

of individual engine andvalve chambers therebetween, each of which when cooperating with the fuel combustion passage in turn arefadapted toform an explosion chamber for the engine,v

means in the valve chamber for completely exburned gases from the engine, a rotary transfer valve comprising a. drum, with a portion o'f its periphery in contact with the inner wall of the pelling any explodedgas from each of the valve chambers, and for preventing same from entercasing, eccentrically mounted in the rotary valve chamber, a plurality of spring-actuated vanes slidably mounted in the enginerotor, formingV with the walls of the casingV individual cham-y bers-therebetween, and adapted to expel the burned gases from said chambers through the engine chamber exhaust port, a plurality of spring-actuated vanes, equal to at least half the number of those. in the engine rotor, slidably mounted in the rotary valve `drum, and forming with the casing a number of^individua.l valve l chambers therebetween, and a ynumber of inwardly bossed ribs formed on the ends of the casing, adapted toform guiding ridges for theengine and valve vanes, the aforesaid valve drum being adapted to coact with the inner wall of the casing, the bossed ribs, and the spring-actuated vanes of the valve to reduce the size of the in- 'l dividual valve chambers to zero, for the purpose of excluding burned gases'thereirom before .the said valve chambers are recharged with fuel. WILLIAM CHISHOLM.