US2243818A - Internal combustion engine - Google Patents

Description

May 27, 1941. 4K. L. HERRMANNy INTERNAL CONBUSTION ENGINE Original Filed May 14, 1957 5 Sheets-Sheet 1 AT oRNEY5 May 27, 1941- K. L. Hr-:RRMANN 2,243,818

INTERNAL COMBUSTION ENGINE Original Filed May 14, 1957 5 Sheets-Sheet 2 May 27 1941- K. L HERRMANN 2,243,818 .INTERNAL COMBUSTION ENGINE original Filed May 14, 1957 `5 sheets-sheet 3 Eiil...

IN V EN TOR. Knel- Z. #fee/MM May 27, 194l K. L. HERRMANN 2,243,818

INTERNAL COMBUSTION ENGINE I I v Original Filed May 14, 1937I 5 Sheets-Sheet 4 I INVENTOR. Kam Z #mem/wf.

TORNEYJ M5L-y2?, 1941. K L HERRMANN 2,243,818

INTERNAL COMBUSTION ENGINE Original Filed May 14, 1957 5 Sheets-Sheet 5 INV-EN TOR;

Afa/2L l. Heee/HHN Patented May 27, 1941 INTERNAL COMBUSTION ENGINE Karl L. Hermann, South Bend, Ind.

Original application May .14, 1937, Serial No. 142,653. Divided and this application -May 6, 1940, Serial No. 333,517 y .12 Claims.

This invention relates to internal combustion engines and particularly to the cooling thereof, the principal object being the provision of a construction that will afford more efficient cooling 4of the engine and particularly certain portions gine so constructed and arranged as to increase the effectiveness of the cooling of the cylinder head of the engine; Athe provision of a cooling system for an internal combustion engine so constructed and arranged as to enhance the effect of the cooling medium particularly upon the seats for the exhaust valves thereof; the provision of a cooling system for an internal combustion engine so constructed and arranged as to provide for an even distribution of the cooling medium around the exhaust passages of the engine in the cylinder head thereof; the provision of a cooling system for an internalcombustion engine in which the cooling medium is irs't introduced into the cylinder head of the engine and is then distributed therefrom to the water jacket for the cylinders thereof; and the l provision of a construction as above described in which the flow of water from the cylinder head passes through a plurality of metered openings into the jacket for the cylinder block.

Other objects of the invention include the provision of a novel cooling system for a barrel type engine; the provision of a cooling system for a barrel type engine including an annular passageway in the cylinder head therefor arranged in .novel manner withrespect to the intake and exrality of individual streams from the bottom of each of the pockets; the provision of a construction as above described in which an individual stream of wateris caused to flow about each of the exhaust passages extending through the cylinder head; the provision of a constructlonas above described in which the discharge ports from each of the pockets serves to meter and restrict the ow of cooling medium from the cylinder head to the jacket for the cylinder block, thereby maintaining a superior pressure of the coolingmedium in the cylinder head as compared to the cylinder block; the provision of a construction as above described in which each of the ports in the aforementioned pockets is formed by a metering plug; and the provision of aconstruction as above described in which the cooling medium is first introduced into the cylinder head of the engine, then transferred to the cylinder block before being discharged from the engine.

The above being among the objects of the present invention, the same consists in certain noved features of construction and combinations of parts to be hereinafter described with reference to the accompanying drawings, and then claimed, having the above and other objects in view.

' In the accompanying drawings which illustrate a suitable embodiment of the present invention and inwhich like numerals refer to like parts throughout the several different views,

Fig. l is a view showing parts in side elevation and other parts in vertical section and disclosed a barreltype-of internal combustion engine constructed according to 'my invention; n

Fig. 2 is a fragmentary sectional view, showing on an enlarged scale the construction of the thrust bearing and of the cam follower, which are carried in the connecting section of one of the double-ended pistons;`

Fig. 3 is a view, in end elevation, taken in the direction of the arrows 3-3 of Flg. 2 and showing the exhaust manifold cover, carburetor and water outlet on an enlarged scale;

Fig. 4 is a sectional view, taken on the line 4-4 of Fig. l, looking in the direction of the ar' rows 4-4 of that ilgure and showing on an enlarged scale the intake and exhaustV valve pockets and also the passages from the carburetor to the 'respective intake valves and the passages through which the cooling fluid travels'around the exhaust valves to the cylinder blocks;

Fig. 5 is a fragmentary sectional view on an enlargedscale, taken substantially on the line 5-5 of Fig. 4, showing a metering device which is located in one of the passages of the coolingv system;

Fig. 6 is a 'fragmentary sectional view, taken on the line 4-4 of Fig. 1 but looking in the op-` posite direction of the arrows 4 4, showing a portion of the carburetor and the connecting passage for the intake manifold;

Fig. 7 is an enlarged sectional view; taken substantially on the line 1-1 of lig. 1, showing the passages through lwhich the cooling iluid travels within the cylinder block;

lFig. 8 is an enlarged sectional view, taken longitudinally through the' cylinder head, having certain parts broken away and showing an intake valve, an exhaustvalve and their relatedY Fig. 9 is a'perspectifve view of the valve operating cam, showing the cam surfaces for operating the intake and exhaust valves;

Eg. luis a fragmentary sectional view taken Y axis thereof, and each cylinder bore has assolcngitudinallyoftheengineandshowingthe' supplyandreturnof luhricanttoandfromthe varimismoving parts of the engine;

Eg. 1 1 is a cross-sectional view, taken on the line Iii-II of-Flg. 10, showing the method of Supplying lubricant to the engine and also the arrangement for return of lubricant to the rervoir;

Fig. 12isadetailed viewonan'enlargedscale ofoneofthethrustbearings,showingtbev grooved surfaces for carrying and distributing theoihand, f Fig. 13 is an eniargedfra sectlo viewslrowingtheventuriforremnngoiltothe.

Themesentinventionisadivisionofmyapf plitlonfor IettersPatent ofthe United States for Improvements in internal combustion engine, iiled May 14, 1937, and seriallymnnbered 142,653. Certain features of the preni; invention are applicable to internal combustion engines whether theyareofthe usualin-linetype of construction,

Y V-type of construction, or of the barrel type of construction, but inasmuch as all features of the 1- invention are particularly adaptable for use in connection with barrel types of engines, the following descption of the present invention will belimited to its application to barrel ty-pe engines only. Fromthis description those skilled in the artwillreadily understand the mannerinwhich the invention may be applied to internal combustion engines of other types without requiring specific mention thereof. Y

Referring to the drawings in which like numerals refer to like parts throughout the several views, there is shown an internal combustion Aengine of the barrel type having twelve cylinders in two groups of six each. As shown in Fig. 1, the engine is composed of two .similar halv. The drive shaft I6 extends .through both halves of the engine. The cylinders are equally spaced in a circle around the drive shaft. 'I'he drive shaft has mounted on it, or integral with it, an

ciated with it one piston, such as 29, of a doubleended piston, designated generally as 36.

Referring still to Fig. 1, the double-ended piston 36 may be seen to comprise a of pistons 29 and'32 connected by a connecting portion 33. The pistons 3U may be operatively connected to the'cam I3 in the manner shown in my copending application for Letters Patent of the United States for Improvements in internal combustion engine, led Oct. 29, 1938, the same being a continuation in part of my previously identied application of which the present applicationis a division, or may be connected as shown herein. In the particular construction shown the cor.- necting portion has formed therein a pair of journals 34 and 35 within which there are mounted roller bearings and Acam followers, such as 3 6 and 31, the cam followers contacting with l the cam I3 and transforming the energy of the pistons into torque for rotating the cam I3.

'I'he structure of the roller bearings, their journais and cam followers may be seen more clearly enlarged portion approximately midway between Y enlarged portion II provide thrust surfaces for A the bearings I2. The shaft IIJ extends the entire length of the engine and is provided with journal surfaces I5 arranged to rotate vin bearings I6. One end of the drive shaft I6 is provided with an ignition distributor I1 and the other end is arranged as at I8 for connection to a coupling device. The cylinder block is formed in two sections I9 and 20, secured gether as at 22. Adjacentthe ends of the cylinder block sections I9 and 20 are cylinder headsv 24 and 24a. The Acylinder block sections are" in Fig. 2,'where there is shown the journal 34 within which there is mounted on needle or roller bearings, such as 36, a shaft 39. This shaft 39 carries the cam follower 36, which, as stated above, contacts with the cam I3. The shaft 39 and roller bearings 38 are retained in position -by washers 40 and snap rings 42. Apertures,r

such as 43, are provided in the washers 4l to permit lubricant to contact the rollers 38. Having roller -bearings on both sides of the cam follower 36 gives ample roller bearing surface.

After explosion, the burnt gases are exhausted from the cylinders by the following means. As may be seen in Fig. 1, each cylinder 28 is provided with an'exhaust opening 44, which is usually closed by an exhaust valve 45, the exhaust valve opening at times to allow the burnt gases to pass into the exhaust passage 46. From each exhaust' passage 46 the -gases pass through the corresponding exhaust conduit 26 to the exhaust manifold 21 and escape therefrom through the exhaust opening 41. The exhaust manifold 21, the exhaust outlet 41, and the several exhaust conduits 26 are shown more clearly in Fig. 3.

Means are also provided for supplying fuel to the various cylinders. As maybe seen in Fig. 3, I have provided a carburetor 48, which is connected to an intake conduit-49 (Figs. 3 and 4). This intake conduit 49 leads to an annular intake manifold 5 0 formed adjacent to the drive shaft and concentric therewith and provided with a casing 62, which is formed as a Vpartition surrounding the inlet valves 53 but excluding the exhaust valves 45 and forming radially outwardly directed pockets-or passages 63 each connecting the manifold 50 with one of the intake valves 5f.` One exhaust valve 45 and one inlet valve 53 is associated with-each cylinder so as to allow the inlet of fuel and exhaust of burnt gases from Y each cylinder. Y

Means are provided for operating the exhaust and inlet valves, which means are shown the most similar as are the cylinder heads, and the de- :j clearly in Figs. 8 and 9. Referring thereto, it

Each of may be seen that associated with the cylinder head 24a there is an exhaust valve 45a and an inlet valve 53a. The valve 45a has a valve stem 54, which is urged by a spring 55 to seat the valve 45a. The valve 53a has'a valve stem 56, urged by a spring 51 to seat the valve 53a.

The stem 54 acting through a conventional tappet 54a bears upon the inner face 58 of the valve cam 59, shown most clearly in-Fig. 9, and the valve stem 56 acting through a tappet 56a bears on the outer face 68 of the cam 59. Similarly, all of the exhaust valves have stems bearing through tappets on the inner face, and all of the inlet valves have stems bearing through tappets on the outer face, and the cam thus operates both the exhaust and the inlet valves.

The axes of the intake valves, such as 53a, lie in the surface of a frustrum of a cone, andthe ends of the cooperating valve tappets are shaped to conform to the cam surface 58 of the cam 59.

The exhaust valves corresponding to valve 45a and their valve stems and tappets are located so that their axes lie in the surface of a frustrum annular, inclined cam surface 58 for the intake v valves is combined with the concentric, annular,

inclined cam surface 68 for the exhaust valves in a single unitary structure.

Referring again to Fig. 1, it may be seen that each exhaust manifold 21 is tapered to permit the continuous and uniform dow of exhaust gases into the exhaust pipe 62 (Fig. 3). The exhaust conduits 26 may be secured to the cylinder head 24 by means of bolts or studs.

In` the operation of the valves, the cylinders fire in regular order in the direction of rotation. The intake valves open in the same order, and gases passing into the intake manifold 50, past the intake valves, are caused to whirl in a rotary swirling action in the short annular rruanifold,v

and thus the heavier vapor particles are prevented from settling, because they are thrown outward'centrifug'ally into the valve pockets 63 (Fig. 4).

Means are also provided for cooling the engine and which means constitute the present invention. Referring `especially to Fig.4 4, there is shown a Water or other cooling medium inlet 64, through which water is introduced v,into the annular compartment 65 formed between 'the partition 52 and the o uter casing. or wall 88 of the cylinder head 24. ,Pinie water thus enters the cylinder head and ,forms a mass, around and between the exhaust valves and travels towardthe longitudinal center of. gie -fengine, passing through ports, such as the port 61. One of the ports 61 is shown more clearly in Fig. 5, wherein it may be seen that the port 61 connects the space 65 with a water-jacket 68 sur-- rounding the cylinders 28. From the jacket 6l (Figs. 1 and 7), the water passes throughan outlet 89 into a water conduit, leading back to the radiator 12. From the radiator 12,*the

permit, the proper amount of Water to ow around the exhaust valves and into the water jackets for the cylinders. By this arrangement the compartment 65 is maintained continuously filled-with water and prevents the possibility of steam collecting in the exhaust cooling compartment. Also by making the passages in the plugs small enough, it is possible to maintain a positive pressure on the water in the jacket for the cylinder head, vgreater than the pressure on the water inthe jacket for the cylinder block, and

thus lessen the tendency of steam to form aroundA the head, as well as to insure a proper flow of water around all of the exhaust passages 44 so as to maintain the seats for the exhaust valves properly c ool and. thus avoid warping of the same. By reason of the fact that the ports 61 are located in the pockets for the exhaust valves, the possibility of excessive hot water collecting in these pockets is eliminated, thus giving more desirable and efficient cooling of the engine. It is also understood that the ports in the plugs 15 may be varied in size so that `a uniform temperature may be maintained throughout by increasing or decreasing the ilow of the cooling medium. The fact `also that the water heated by the exhaust surrounds the intake manifold insures the maintenance of the fuel at a proper temperature. A steam relief port 61a, smaller than the metering ports 15, connects the compartment 65 in the head with the water-jacket 68 at their uppermost portions to permit any steam that might form in the head under unusual circumstances a ready -escape to the outlet 69.

Means are provided for insuring the proper lubrication of all the moving parts of the engine and while any suitable means may be provided for 'this purpose, one suitable means is shown by way of illustration. Referring to Figs. 10, 11, l2 and 13, and especially to Fig. 11, it may be seen that there is provided an oil reservoir 16, from which oil may flow by a conduit 11 to a central chamber 18 formed in the engineblock adjacent water is pumped by the pump 13 through the e to the drive shaft l0. As may be seen more clearly in Fig. 10, the drive shaft I0, adjacent to the outlet from the conduit 11, may be but is not necessarily provided with a series of spiral baffles 19 and 80. As may be seen, with the drive shaft I9 rotating in a clockwise direction (as viewed from the left in Fig. 10), the spiral Vbaiiles will act to aid in forcing the lubricant in opposite directions from the conduit 11, forcing it to the bearings I5 and 82, and in the opposite direction to the thrust bearings I2. The thrust bearings I2are shown on an enlarged -scale in Fig. 12 and are each provided with a plurality of4 spiral grooves, such. as 84, whereby the oil is thrown onto the enlarged portion Il ofthe drive shaft I0 and outwardly therefrom to lubrieate the cam' followers 36, the roller bearings therefor, the cam I3 and the pistons, during their movement in the cylinders. The oil collects in the lower part of the crank case, as at 85. (Figs. 1-0 and 11), and is forced therefrom by pressure in the crank case developed from the blow-by past the pistons. The oil is forced, through a'Venturi nozzle 86, as indicated in Fig. 13, into a return conduit 81, from which it flows back to-the supply tank 16. In passing out of the Venturi nozzle 86 into the conduit 81, the flow of the oil creates a suction, which draws oil from the opposite ends of the engine through the conduits 89 leading thereto. Thus oil forced towards the ends of the engine bythe bales 88 or otherwise passes outwardly to lubricate. the valve mechanism, and

vent opening of the reservoir in inverted flying.

It-is to be understood that oil passed through the journal I5 (Fig. 10) is discharged against the cam 59 and thrown centrifugally against the ends of the valve stems 5I and 56.

It is believed that the operation of the engine will be apparent from the above description.A

Fuel injected into the cylinders through the intake manifold 59 from the carburetor 4B, at times permitted by the opening of the valves 53 as controlled by the cam 59, is exploded by the spark plugs, which may be inserted as at l (Fig. 10). The movement of the pistons outward reacts through the central beam, through the cam followers 35, upon the cam I3, and thus rotates the shaft I9. At this point the exhaust valves I5 are opened by the cam 59, and the exhaust gases escape through the exhaust manifold 21. The cam 59 is driven by the shaft Il and, as stated, operates the exhaust and intake valves. Ihe engine is cooled by the cooling system, previously described, and is lubricated by the lubricating system, also previously described.

It is to be understood that the above described embodiment of the invention is for the purpose of illustration only, and various changes may be made therein without departing from the spirit of the invention, the scope of which is commensurate with the appended claims.

What is claimed is: f

1. In an internal combustion engine of the Y lclass wherein a cylinder block is provided with a cylinder head removably secured thereto, the cylinder head being provided with an inlet port and an outlet port for each of said cylinders .and the cylinder block and the cylinder head being each provided with a water jacket, vthe combination with said cylinder head of an exlhaust passage connected with each of said outa removable cylinder head and said block and said. head being each provided with a. water jacket, the combination with said block and head of a plurality of passages connecting the water jacket for said head with the water jacket for said block, and a metering member removably received in each of said passages restricting the flow of water to flow therethrough.

4. The method ofv cooling an internal combus-v tion engine having a water jacketed cylinder block and a water jacketed cylinder head having a plurality of exhaust passages arranged therein, comprising introducing a cooling medium into thevwater jacket for said head, causing said cooling vmedium in said water jacket for said head to iiow in a plurality of individual streams,

into said waterA jacket for said block and with each of said streams flowing around a corresponding one of said exhaust passages, and then Said cooling medium from. the .water jacket for said block.

5. In an internal combustion engine of the barrel type wherein a plurality of cylinders are provided in a cylinder block and are arranged with theiraxes paralleltotheaxisoftheengine drive shaft and grouped circularly thereabout, thecylinder block being provided with a water jacket, and the cylinder block being provided with a water jacketed cylinder head providing an inlet and exhaust port foreach of said cylinders, the combination with said cylinder head of an annular intake manifold formed integrally therewith in surrounding relation with respect to the drive shaft, the radially outer wall of said intake manifold being formed to provide an outwardly directed pocket connecting each of said inlet ports with saidintake manifold, said outer wall of said intake manifold forming between each adjacent pan'r of said pockets a radially outwardly opening pocket open to the in,

terior of said water jacket for said cylinder head, andan exhaust passage formed integrally with said head in communication with each of said exhaust ports and projecting through each of the last mentioned pockets in spaced relation to v*the side walls thereof.

gine being provided with a plurality of passages for the ow of cooling medium between said 'pockets and the water jacket forsaid cylinder Y block.

2. In an internal combustion engineof the Y class wherein a cylinder block is provided with a removable cylinder head, the cylinder head being provided with inlet and exhaust ports and I each exhaust -port being provided with an associated passage for the discharge of exhaust gases therethrough, the combination with said cylinder `head of a water jacket for confining .a flow. of .cooling medium in contact therewith,

means for introducing -a ilow of cooling medium 1 into said water jacket for the head, and means' for discharging said cooling medium from said' water jacket for the head ina plurality of separate streams, the cooling medium of each stream flowing around a corresponding one of 6. In an internal combustion engine of the barrel type wherein a plurality of cylinders areA provided in a cylinder block and are arranged withtheir axesparalleltotheaxisoftheenginev drive shaft and grouped circularly thereabont,

the cylinder block being provided with a water jacket, and the cylinder block being provided with a water 'jacketed cylinder head providing an inlet and exhaust port for each of said cylinders, the-combination with said. cylinder head l of an annular intake manifold formed integrally therewith in surrounding relation with respect to the drive shaft, the`radially outer wall Y of said intake nyanifoldbeing formed to provide an outwardly directed pocket connecting each of said inlet ports vwith said intake manifold, said outer wall of said intake manifold forming Vbetween'eachadjacentpair of saidpocketsa each of the last mentioned pockets affording a now of cooling medium between the water jacket for said cylinder head and the water jacket for said, cylinder block.

7. In an internal combustion engine of the barrel type wherein a plurality of cylinders are provided in a cylinder block and are arranged with their axesparallel to the axis of the engine drive shaft and grouped circularly thereabout, the cylinder block being provided with a water jacket, andthe cylinder block being provided with a water jacketed cylinder head providing an inlet and exhaust port for each of said cylinders, the combination with said cylinder head of an annular intake manifold formed integrally thereports with said intake manifold, said outer wall vof said intake manifold forming between each f adjacent pair of saidv pockets a radially outwardly with in surrounding relation with respect to the drive shaft, the radially outer wall of said intake manifold being 1formed to provide an outwardly directed pocket? connecting each .of said inlet ports with said intake manifold, said outer wall of said intake manifold forming between each adjacent pair of said pockets a radially outwardly opening pocket open to the interior of said Water jacket for said cylinder head, an exhaust passage formed integrally with said head in communication with each of said exhaust ports and projecting t through each of the last mentioned pockets in spaced relation to the side Walls thereof, said cylinder head having a passage therein adjacent the bottom of each of the last mentioned pockets affording a flow of cooling medium between the water jacket for said cylinder head and the water jacket for said cylinder block, and a metering plug in each of said passages.

8. In an internal combustion engine of the barrel type wherein a plurality of cylinders are provided in a cylinder block and are arranged with their axes parallel to the axis of the engine drive shaft and grouped circularly thereabout,

the cylinder block being provided with a water jacket, and the cylinder block being provided with a water jacketed cylinder head providing an .intake manifold forming between each adjacent pair of said pockets a radially outwardly opening pocket open to the interior of said water jacket for said cylinder head, an exhaust passage formed integrally with said head in communication with each of said exhaust ports and projecting through each of the last mentioned pockets in spaced relation to the side walls thereof, means for introducing a cooling medium into the water jacket for said cylinder head, and means for discharging said cooling medium from the water jacket for said cylinder block.

9. In an internal combustion engine of the barrel type wherein a plurality of cylinders are provided in a cylinder `block and are arranged with their axes parallel to the axis of the engine drive shaft and grouped circularly thereabout,

the cylinderblock being provided with a water jacket, and the cylinder vblock being provided witha water jacketed cylinder head providing an inlet and exhaust port for each of said cylinders, the combination with said cylinder head of an annular intake manifold formed integrally therewith in surrounding relation with respect to theA opening pocket open to the interior of said water jacket for said cylinder head, an exhaust passage formed integrally with said head in communication with 'each of said exhaust ports and projecting through each of the last mentioned pockets in spaced relation to the side walls thereof, said cylinder head having a passage therein adjacent the bottom of each oflthe last mentioned pockets affording a flow of cooling medium between the water jacket for said cylinder head and the water jacket for said cylinder block, and an apertured plug removably received in each of said passages, said plugs being removable whereby to enable replacement of each thereof with a plug having a different sized aperture therein whereby to vary the distribution of flow of cool.- ing medium from the water jacket for said cylinder head to the water jacket for said cylinder block.

10. In an internal combustion engine of the class having a rotatable shaft, a plurality of cylinders arranged with their axes parallel to said shaft and grouped around said shaft, pistons reciprocable in said cylinders, means interconnecting said pistons and said shaft for effecting rotation of said shaft upon reciprocation of said pistons in said cylinders, and cylinder heads for said cylinders, the combination with said .engine of a water jacket for said cylinders, a water jacket for said cylinder heads having discharge openings leading into the Water jacket for said cylinders, and means for circulating a cooling liquid through said jackets inthe direction of toward said cylinder head jacket and from said cylinder jacket, said discharge openings being of such combined area as to cause a greater pressure on said liquid in said cylinder head jacket than in said cylinder jacket during operation of said engine.

11. In an internal combustion engine of the class having a rotatable shaft, a plurality of cylinders arranged with their axes parallel to said shaft and grouped around said shaft, pistons reciprocable in said cylinders, and means interconnecting said pistons and said shaft for effecting rotation of said shaft upon reciprocation of said pistons in said cylinders, the combination with said cylinders of a unitary cylinder head applicable to all of said cylindersy an annular fuel mixture intake passage formed integrallywith said cylinder head, radially outwardly directed passages connected with said annular passage serving to connect said annular passage with each of said cylinders, said radial passages forming between them radially outwardly directed pockets, ari exhaust passage for each of said cylinders connected thereto through said pockets and arl ranged in spaced relation to the walls of said drive shaft, the radially outer wall of said intake manifold being formed toprovide'an outwardly directed pocket connecting each of said inlet pockets and extending outwardly therefrom, a water jacket for said cylinder head enclosing said intakeand exhaust passages, a water jacket for said cylinders, means forintroducing a cooling liquid to said jacket for said cylinder head, and conduits .for the flow of cooling liquid from said head jacket to said cylinder'jacket leading to said cylinder jacket from the bottom of said pockets.

12. In an internal combustion engine of the class having a rotatable shaft, a plurality of cylinders arranged with their axes parallel to said shaft and grouped around said shaft, pistons re.-

f ciprocable in said' cylinders, and means interconnecting said pistons and said shaft'for lefiecting rotation of said shaft upon reciprocation of said pistons in said cylinders, the combination with said cylinders of a unitary cylinder head applicable to all of said cylinders, an annular fuel mixture intake passage formed integrally with said cylinder head, radially outwardly directed passages connected with said annular passages serving to connect said annular psage with each of said cylinders, said radial passages forming between them radially outwardly directed pockets, an exhaust passage for each of said cylinders connected thereto through said pockets and arranged in spaced relation lto the walls of said pockets and extending outwardly therefrom, a

water jacket for said cylinder head enclosing said intake and exhaustpassages, a water jacket for said cylinders, means for-introducing a cooling liquid to `sam-l jacket for said cylinder head, and

Yconduits for the iiow of cooling liquid from said

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