US3079902A - Air-cooled cylinder head, in particular for internal combustion engines - Google Patents

Description

March 5, 1963 w. ULBRlcH 3,079,902

AIR-COOLED CYLINDER HEAD, IN PARTICULAR FOR Filed Nov. 1e, 1959 INTERNAL COMBUSTION ENGINES 4 Sheets-Sheet 1 @wu/WE m March 5, 1963A w ULBRlcH 3,079,902

IR-COOLED CYLINDER HEAD, IN PARTICULAR FOR INTERNAL COMBUSTION ENGINES Filed NOV. 16, 1959 4 Sheets-Sheet 2 2.1. I? L X Fig. 4

March 5, 1963 w. ULBRICH AIR-COOLED CYLINDER HEAD, IN PAR ULAR FOR INTERNAL COMBUSTION ENGI Filed Nov. 16, 1959 4 Sheets-Sheet 3 March 5, 1963 ULBRICH 3,079,902

1N PARTICULAR FOR AIR-cooLED CYLIN 'R HEAD,

INTERNAL coMBusToN ENGINES Filed Nov. 16, 1959 4 Sheets-Sheet 4 Fig. l0

@Mee/.4W fa/AJ United States Patent Ofce 3,079,902 Patented Mar. 5, 1953 3,979,902 ALi-CGLED CYLHJDER IEAD, IN PARTICULAR FOR HNTERNAL CGMBUSTION ENGINES Woiigang Uiorich, Munich, Germany, assignor to Gesellschaft fur Lindes Eismaschinen Aktiengesellschaft,

Hoiiriegeisin'euth, near Munich, Germany, a company of Germany Fiied Nov. 16, 1959, Ser. No. 853,213 Claims priority, application Germany Nov. 15, 1958 7 Claims. (Cl. 12S-41.69)

This invention relates to internal combustion engines, in particular, in line engines, of the overhead valve type, and is concerned with the provision of an improved aircooled cylinder head for such an engine whereby the cylinder head is formed as an integral casting at least including a cylinder head bottom, two gas ducts and cooling fins, and provided with a pan forming a rocker arm chamber and being a part of the integral casting or a mounted part.

Especially in air-cooled internal combustion engines, the ability to sustain thermal stress, and, hence the output capacity, depends largely on the strength of the cylinder head. Since for known reasons it is advantageous to install certain units, such as valve arrangements, fuel nozzle, extraneous ignition device, starter device, possibly pre-combustion or turbulence chamber, etc., in the cylinder head, over the main compression space of the engine, the area remaining for cooling is naturally reduced, so that also the necessary precautions for sufiicient cooling are more difficult to meet. These built-in units also cause the sweeping cooling-air stream to be divided into several partial streams through and around the cylinder head.

It is known that during operation different temperatures prevail at the individual spots of the cylinder head. There is, then, danger especially from the spots exposed to the highest temperatures, the more so as these spots are as a rule not directly and suiciently accessible to the cold cooling-air stream. For better heat transfer and better cooling, cooling ribs are used which in known manner surround the cylinder head walls and possibly the attached units and which may be connected together.

The present invention is concerned with the problem of greatly improving the cooling effect at the spots to be cooled intensively, i.e., the spots especially subjected to high thermal stresses, which are positioned in the main direction of the cooling air stream one approximately after the other, one of said spots lying about at the narrowest pass between the gas ducts projecting from the cylinder head bottom and another one being a projection from the cylinder bottom. Said projection may be a spark plug, depending on the construction of the internal combustion engine in the case of an Otto-engine, or an injection nozzle in the case of a Diesel-engine, or if in the case of a Diesel-engine a precombustion or turbulence chamber is arranged in the cylinder head, the portion of said chamber which projects from the cylinder head bottom. Such a cylinder head, wherein between the aforementioned portions and parts there are arranged channels for cooling air by which a main cooling -air stream is divided into at least one central partial stream and into outer partial streams is characterized, according to the invention, both in that at least a part of the central partial stream heated at a first spotwhich is especially subjected to thermal stress and therefore preferably to be cooledis branched off and conducted outwardly to become part of an outer partial stream, and in that at least a part of a comparatively cool outer partial stream is branched off before said part branched off from the central partial stream combines with said outer partial stream and is conducted inwardly to inner cooling air channels to become at least part of a central partial stream at a place behind the Vto branch-off of said part of the central partial stream thus sweeping a second spot which is especially subjected to thermal stresses and therefore preferably to be cooled, especially so that substantially in all sectional planes normal to the direction of flow adequate cross-sections are available for the individual partial streams and for the total air stream of the flow. The forced conductions are advantageously so designed that at least some of the partial streams-in a projection on at least one plane parallel to the direction of flow-cross, branch, and/or unite with each other. The forced conductions are advantageously obtained by a suitable conformation of the walls and of the cooling ribs, possibly in conjunction with the built-in units. The advantage of this over the possibility of arranging the forced conductions as special structural parts or as conformations on, for example, the cooling air conduction guide plates, etc., is that they additionally carry away heat from the body of the cylinder head. It is also within the scope of the invention to arrange cooling air ilow channels in the lower part of the body of the actual cylinder head, and this preferably in such a way that they start from the end area exposed to the air blast, are directed outwardly within the front cylinder head fastening screws, and .issue at the lateral outer wall, and/or that, starting from the lateral outer Wall, they are directed inwardiy within the rear cylinder head fastening screws and issue at the rear end area, and/ or that they start for instance at the front end area eccentrically, are directed obliquely toward the center and possibly even downwandly, and are passed between the valve ducts. All cooling air-flow channels are, according to the invention, to be so directed and so accessible that they can be cleaned in the assembled state of the internal combustion engine; advantageously, that cleaning can be done through closeable openings in the air conduction `guide plates. Cooling ribs connecting individual built-in `units-in particular, those between the valve ducts, that is, at points which exhibit great temperature differences relatively to each other-should acconding to the invention be designed roof-shaped, i.e., having a cross-section formed as obtuse angle or arc section. A good elasticity is achieved by such ribs, so that in them stresses are not transmitted from one built-in part to another, or only to an Vinsignificant degree, while flat ribs are able to absorb high compressive and tensile forces normally tending to deorm the cylinder head. Also it may, in some cases, be advantageous to arrange built-in units, such. as valves,y injection nozzle, precombustion or turbulence chamber, spark plug, etc., asymmetrically and/or eccentrically in such a way that flow cross-sections of unequal size, which take better account of differing thermal conditions are formed, so that, according to the desired flow, channels may be formed, by which is to be understood primarily that the quantities for air volume, cross-section area, swept surface, rate of ow, temperature gradient, etc., 'are adaptable to the prevailing conditions.

In the figures of the accompanying drawing embodiments of the invention are shown. The cylinder heads are imagined as divided into layers parallel to the cooling ribs, capital letters being used to designate the layersformed by cooling ribs and small letters for the intermediate layers.

As a first embodiment a cylinder head is represented in which, at front in the direction of air iiow, an eddy chamber, and therebehind an outlet and an inlet valve are arranged. FIG. 1 shows a longitudinal section through the cylinder axis; FIG. 2, a transverse section through the valve axes, namely, the right half 2a seen in the direction of the cooling air stream, and the left half 2b in the opposite direction of the cooling air stream; FIG- URES 3, 4 and 5, `sections through layers in planes normal to the cylinder axis. In FIG. 3 is represented a section ment of cooling air-flow channels are provided. The Y.

cylinder heard consists essentially of a cylinder head bottom portion y1, located between the combustion zone ceil ing 2 and rib F, a plate-shaped ktop wall 3 parallel to the Ycooling ribs which by laterally extending edge 4 is designed as oil collecting basin 5, therebetween walls extending in Vthe direction of the cylinder axis, ofvwhich a wall 6 contains a turbulence chamber 7 and in part the bores 8 and 9 for an injection nozzle and for a heater plug, respectively, a wall 10 surrounds the inlet duct 11, a Ywall 12 contains a bore 13 for a cylinder head fastening screw, and cooling ribs connecting and surrounding the walls. In wall 10 are contained a bore 14 to receive a cylinder head fastening screw and a bore 15 through which is'p'assedl a valve push rod. In FIGURES 3, 4 and 5V only half of the cylinder head is represented, the other half being arranged approximately symmetrically and containing the outlet duct instead of the inlet duct.

The cooling air stream impinges in the directionrof the arrows 16, frontally on the cylinder head and is split at the level of the cooling ribs A, B, C and D in such a way that itow's past the laterally arranged cooling ribs. In layer e there is disposed in the body of the cylinder head bottom 1 a channel 17, into which cold air enters, which air by' intensive cooling is strongly heated before it can iiow out at' the sides and discharge'between the cooling ribs E and F toward -the rear. Therebelow, in layer d, there is disposed, with a lateral inflow opening, the channel 18 which extends obliquely backward to the center line. Through this channel 18 relatively slightly heated air ows in between `the cooling ribs D Yand E, and, after having beenA strongly heated -in theY body of the cylinder head bottom 1, in particular under the outlet valve channel, discharges centrally to the rear. Between ribs D and E, behind the' inlet opening of channel 18, there is a blocking nose I9, which forces at least a sucient part ofthe air to low into the channel 18. In layer f, the cooling air stream 16 is divided into streams 20 and 21, which unite between wall- 6 of the turbulence chamber 7 and wall 10 of the valvechannel and, jointly as a partial stream 22, cool the hottest point at Vthe surface of the cylinder head bottom 1. Behind wall 6 there arises -from the cylinder 'head' bottom 1 a vertical rib 23 which extends backward in the direction of the partial stream 22 and from it receives also an intensive cooling. In layer g, wall 6 is connected with wall 12, so that in this layer only a cold Vpartial, stream 24 can flow outside of wall 12, which stream is deected by nose 25 likewise toward the center at the hottest point, where it can unite with the partial s-trearn- 22 below. The amount of cold air conducted from the outside to the hottest point in the center can be further increased by a part of the partial stream 26, in rlayer h, which is deliected vinto layer g by a recess Z7 and Vby a nose 28. By the deflection Aof the partial streams 20 and 24 and a part of 27 from the outside to the inside, air Yis lost at the outer face of wall 10, which is replaced in Y thatv in layer h a partial stream 29 is conducted from the Vinside to the outside between walls 6 and 10, on the one hand, and wall 12, on the other hand, which partial stream can allow intov the layers between ribs G and H, or respectively G and F, so that thereby the partial streams in themselvesand the total air stream'are compensated. Be- Ytween wall 6 and wall V10, thereA then ow the partial streams 24 and in part 26 coming from the lower layer. VThere occurs'V in theY layers a multiple branching and joining of partialstreams Vwhich cross vertically, with the provision that relatively cold air is conducted tothe most layers and due to the arrangement of the noses 25 and 28 Y and of the recesses 27 Iand 30, a forced conduction of the partial streams takes place. The design is, further, such that substantially in all sectional planes normal to the Y direction of ow adequate cross-sections are available for the individual partial streams and for the total air stream in order that an undesired throttling and hindering of the partial streams is avoided, no dead spaces are formed in which the cooling air can stagnate; thereby also great accelerations and retardations of the cooling air streams are' avoided, in order that the power requirement for the production of the cooling air stream will remain low. v.The air velocity in the narrowest cross-section between wall `6 and wall 10 can then of course be greater (1) because less space is available for the channel cross-sections, and (2) because at this point cooling is improved by i11- creased air velocity, which is quite' desirable.

Rib 23 is designed relatively wide at the foot and passes into the cylinder head bottom 1 with Y.a large radius of curvature so as to insure high strength and good heat conduction. For these reasons also the transition from the cylinder head bottom 1 to the walls 10 is strongly rounded. Continuous ribs 31 and 32 are designed in roof form because this results in a more elastic connection between the two walls receiving the valve ducts, so that` of thev injection nozzle, an extraneous ignition device may Y be provided in this case. The cylinder head bottom 1 has a boreV 42 into which bores 43 open obliquely, so that cold air can flow through the opening 44 at very hot and imperiled points. In layer d there flow the cooling air partial streams 45 and 46, the hot stream 46 being conducted outwardly, while in layer f the partial streams 47 and 48 elect an intensive coolingy of the points between nozzle bore 41 and wall 10,'and, moreover, a partial stream of cold airis blown into the opening 44 of bore 43. The combined streams' of parts of 47 and 48 then flow between the walls 10 toward the rear and at the same time cool the upper face of the cylinder head bottom through rib 23, which in this case is discontinuous in the narrowest cross-section for the enlargement thereof. The partial stream 45 passes through recess 49 behind nose 50 between the cooling? ribs F and G. In layer g, the partial 'stream 51 goes through recess 52 downwardly, While the partial stream 53 is conducted away outwardly and rearwardly between wall 6 and the nozzle, or, respectively, the fastening screw forV the nozzle holder which passes through `bore 54. Another partial stream 55 ca-n ow laround the nozzle into the passage cross-sections between the walls 10. Here,too, a branching, joining, and crossing of partial streams takes place resulting in the effect according to the invention.

By the conformation of the noses in the intermediate Vlayersand the recesses in the cooling ribs, the forced con- Y duction of. the partial streams can be brought about. FIG. l0 shows a variant by arrangement of the cooling air- tlow channels 61, 62 and 63 in the cylinder head bottom 1.

It is within the scope of the invention that the measures are applicable also in cylinder heads having ribs inV any Vdesired position; Y

To arrange built-in units, such as valves, injection nozzle, precombustion or turbulence chamber, spark plug, etc., asymmetrically or eccentrically in such a way that in the zone of the inlet duct on the one hand, and the outlet Yduct on Vthe other hand, passage cross-sections of unequal size are formed so as to be able to take better account of the thermal conditions, e.g., to -be able to cool in higher degree the inlet duct or the outlet duct, if necessary, by an increase of the cooling air ilow;

That the channels ior the partial streams are formed not only in the intermediate layers, but also in the layers receiving the cooling ribs;

That channel d3, for example, is passed also in the body of the cylinder head between the fastening screw for the nozzle holder and the nozzle itself and through several superimposed layers;

That instead of the oil-collecting basin formed out of the bottom of the uppermost cooling ribs and lateral walls raised internally, there may be provided such a basin formed out of a special structural part.

To improve tde cooling conditions and thus to malte the cylinder head capable of sustaininfy greater thermal stress, thereby permitting an increased output oi the internal combustion engine, the represented measures according to the invention may be arranged singly, partly, or jointly, and in any desired nurnber and bilaterally, symmetrically or only unilaterally.

l claim:

1. Air-cooled cylinder head for an internal combustion engine, in particular an inline engine, of the over-head valve type formed as an integral casting at least including a cylinder head bottom, two gas ducts and cooling ns, and provided with a pan forming a rocher arm chamber being a part of the integral casting or a mounted part, on which cylinder head at least two spots especially subjected to high thermal stresses and therefore preferably to be cooled are positioned in the main direction of the cooling-air stream one approximately after the other, one oi said spots lying about at the narrowest pass between the gas ducts and another one being a projection from the cylinder head bottom, and whereby between the aforementioned portions and parts there are arranged channels for cooling air by which a main cooling air stream is divided into at least one central partial stream and into ou er partial streams, characterized both in that at least a part of the central partial stream heated at the iirst spot which is especially subjected to thermal stresses and therefor preferably to be cooled is branched ofi and conducted outwardly to become part of an outer partial stream, and in that at least a part of a comparatively cool outer partial stream is branched-ofi before said part branched-oli from the central partial stream combines with said outer partial stream and is conducted inwardly to inner cooling air channels to become at least part of a central partial stream at a place behind the branch-od of said part of the central partial stream, thus sweeping a second spot which is especially subjected to thermal stresses and therefore preferably to be cooled.

2. Air-cooled cylinder head as dened in claim 1, further characterized in that at least part of said central partial stream after being heated by heat exchange with a forwardly lying thermally highly stressed part of the cylinder head is abducted into at least one outer partial stream, and in that at least a part of the outer partial stream is abducted into the remaining part of said central partial stream, and is swept over a rearwardly lying thermally highly stressed part of the cylinder head whereby the abductions of the parts of the central and outer partial streams are provided before said abducted parts mingle with the remaining parts of the partial streams.

3. Air-cooled cylinder head as deiined in claim 2, charcteriaed in that the compulsory directions for the abducted portions ot the component partial streams are established by shaping the walls and cooling ribs in conjunction wit the installations.

Il. Air-cooled cylinder head as deiined in claim 2, characterized in that the ribs connecting the individual installations between the valve ducts are constructed rooishaped,

5. Air-cooled cylinder head, as defined in claim 1, characterized in that in the body of the actual cylinder head bottom, there are arranged cooling air stream channels whereo those which start from the front face eX- posed to the blast are directed outwardly within the front cylinder head fastening screws and emerge on the lateral external wail and the others which start on the lateral outside wall are directed inwardly within the rear cylinder head fastening screws and emerge on the rear front surtace and still others which start approximately on the face oi the front surface eccentrically are directed diagonally to the center, and somewhat directed downwardly and are conducted between the valve ducts and emerge on the rear iront surface.

6. Air-cooled cylinder head as dened in claim 1, characterized in that installations including gas ducts, cooling dns and the projection from the cylinder head bottom as a spot of high thermal stress are arranged asymmetrically.

7. Air-cooled cylinder head according to claim l, characterized in that portions of the cylinder head including especially the walls of the gas ducts and the cooling ns and the parts projecting from the cylinder head bottom are provided with channel forming means such as salients, recesses, dividing walls and holes, which form cooling-air channels for conducting the branched-ott parts of the partial streams along such predetermined paths.

References Cited in the le of this patent UNlTED STATES PATENTS 2,725,045 Flatz et al. Nov. 29, 1955 2,887,994 Morris May 26, 1959 FOREIGN PATENTS 859,982 Germany Dec. 18, 1952 862,076 Germany Jan. 8, 1953 862,690 Germany Ian. 12, 1953

Claims (1)

1. AIR-COOLED CYLINDER HEAD FOR AN INTERNAL COMBUSTION ENGINE, IN PARTICULAR AN IN-LINE ENGINE, OF THE OVER-HEAD VALVE TYPE FORMED AS AN INTEGRAL CASTING AT LEAST INCLUDING A CYLINDER HEAD BOTTOM, TWO GAS DUCTS AND COOLING FINS, AND PROVIDED WITH A PAN FORMING A ROCKER ARM CHAMBER AND BEING A PART OF THE INTEGRAL CASTING OR A MOUNTED PART, ON WHICH CYLINDER HEAD AT LEAST TWO SPOTS ESPECIALLY SUBJECTED TO HIGH THERMAL STRESSES AND THEREFORE PREFERABLY TO BE COOLED ARE POSITIONED IN THE MAIN DIRECTION OF THE COOLING-AIR STREAM ONE APPROXIMATELY AFTER THE OTHER, ONE OF SAID SPOTS LYING ABOUT AT THE NARROWEST PASS BETWEEN THE GAS DUCTS AND ANOTHER ONE BEING A PROJECTION FROM THE CYLINDER HEAD BOTTOM, AND WHEREBY BETWEEN THE AFOREMENTIONED PORTIONS AND PARTS THERE ARE ARRANGED CHANNELS FOR COOLING AIR BY WHICH A MAIN COOLING AIR STREAM IS DIVIDED INTO AT LEAST ONE CENTRAL PARTIAL STREAM AND INTO OUTER PARTIAL STREAMS, CHARACTERIZED BOTH IN THAT AT LEAST A PART OF THE CENTRAL PARTIAL STREAM HEATED AT THE FIRST SPOT WHICH IS ESPECIALLY SUBJECTED TO THERMAL STRESSES AND THEREFOR PREFERABLY TO BE COOLED IS BRANCHED OFF AND CONDUCTED OUTWARDLY TO BECOME PART OF AN OUTER PARTIAL STREAM, AND IN THAT AT LEAST A PART OF A COMPARATIVELY COOL OUTER PARTIAL STREAM IS BRANCHED-OFF BEFORE SAID PART BRANCHED-OFF FROM THE CENTRAL PARTIAL STREAM COMBINES WITH SAID OUTER PARTIAL STREAM AND IS CONDUCTED INWARDLY TO INNER COOLING AIR CHANNELS TO BECOME AT LEAST PART OF A CENTRAL PARTIAL STREAM AT A PLACE BEHIND THE BRANCH-OFF OF SAID PART OF THE CENTRAL PARTIAL STREAM, THUS SWEEPING A SECOND SPOT WHICH IS ESPECIALLY SUBJECTED TO THERMAL STRESSES AND THEREFORE PREFERABLY TO BE COOLED.

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