US3099983A

US3099983A - Air-cooled internal combustion engine

Info

Publication number: US3099983A
Application number: US97045A
Authority: US
Inventors: Orlando Luigi Enrico; Corradi Camillo
Original assignee: Alfa Romeo SpA
Current assignee: Alfa Romeo SpA
Priority date: 1960-03-24
Filing date: 1961-03-20
Publication date: 1963-08-06
Anticipated expiration: 1980-08-06

Description

1963 L. E. ORLANDO ETAL 3,099,983

AIR-COOLED INTERNAL COMBUSTION ENGINE Filed March 20, 1961 4 Sheets-Sheet 1 o 11 f Q lze T I l ,z- 4 -a so- 8" f; 3

1963 E. ORLANDO ETAL 3,099,983

AIR-COOLED INTERNAL COMBUSTION ENGINE Filed March 20, 1961 4 Sheets-Sheet 2 Aug. 6, 1963 L. E. ORLANDO ETAL AIR-COOLED INTERNAL COMBUSTION ENGINE 4 Sheets-Sheet 3 Filed March 20, 1961 Aug. 6, 1963 1 E. ORLANDO ETAL AIR-COOLED INTERNAL COMBUSTION ENGINE 4 Sheets-Sheet 4 Filed March 20, 1961 United States Patent 3,099,983 AIR-COOLED INTERNAL COD/BUSTIQN ENGINE Luigi Enrico Orlando and Camillo Corradi, Milan, Italy,

assignors to Alfa Romeo S.p.A., Milan, Italy, a company of Italy Filed Mar. 20, 1961, Ser. No. 97,645 Claims priority, application Italy Mar. 24, 1960 8 Claims. (Cl. 123-4161) It is an object of the present invention to provide an air-cooled internal combustion engine permitting an elevated degree of cooling with a ventilation :of comparatively moderate rate of airflow and which, in the case of a plurality of cylinders in row, possesses a structure of great simplicity and sturdiness and is provided with a particularly low degree of noisiness under operation.

The air-cooling by forced ventilation of internal combustion engines has been realized heretofore generally by means of a flow of air directed transversally with respect to the axis of the cylinder. By that ventilating system the head and the cylindrical part of the cylinder are cooled in parallel by two portions of the same air current and are thus subjected to a cooling action substantially equal for both; since the head has to disperse a quantity of heat that is much larger than that emitted by the cylinder, this ventilating system is not rational and an attempt at remedying this defect was often made by making the cylinder heads of aluminium, which metal had an internal heat conduction greater than cast iron, of which the cylinders are generally made.

According to the present invention the cylinder or each cylinder is cooled by means of a current of air directed as a whole parallel to the axis of the cylinder, so as to meet first the head and then the cylinder. The head is thus swept by all of the cold air and gives off a comparatively large quantity of heat, and the air comes into contact with the cylinder after it has been partly heated by the head, but always in total quantity. Thereby a more uniform distribution of the temperature in the cylinder and head unit is attained. An effective cooling of the head however still constitutes a problem because the head usually includes the exhaust and suction con duits and the respective valves with the rockers controlling them; those elements constitute as many obstacles to the current of cooling air which is directed against the head.

According to the present invention this inconvenience is reduced by arranging the axes of the suction and exhaust valves, the rocking levers controlling said valves, and the axes of the suction and exhaust conduits substantially in the same plane parallel to or containing the axis of the cylinder, preferably at right angles to the crankshaft.

By this arrangement it has been possible to realize a very efiective cooling of the head, not only because a larger portion of the external surface of the head is exposed to the air current, but also because the portion of exhaust conduit which must be integral with the head and which always is at high temperature, is thus very short.

According to a preferred embodiment ot the invention the head of the cylinder or of each cylinder of an engine having the above defined structure, which can be of cast iron, includes a comparatively thin cylinder head part providing a seal on the cylinder bore and provided with fins the upper ridges of which are fixed to, and preferably integral with an annular member of comparatively great thickness, which has the task of distributing to the and, therefore, of the aforesaid thin portion, the concentrated reactions of bolts which hold the head on the cylinder. The ventilating air then is made to pass within the space defined by said annular member, said fins and ice said head part and is converged against said fins and head par-t thereby removing a considerable amount of heat from the fins and from said thin cylinder head pant by virtue of the comparatively low difierence of temperature between the two faces of the latter.

In the case of plural-cylindered engines in line the structure according to the invention is particularly important because, while in a single cylinder engine it is possible to give the exhaust conduits and suction conduits the direction wanted, this is not possible with an engine having a number of cylinders in line, especially if the number of cylinders is greater than two, owing to the necessary accommodation of the suction and discharge manifolds.

The practical embodiment of the invention then provides the possibility of attaining other important advantages which will be made evident by the following description, given by way of example, of an engine according to the invention, as represented diagrammatically in the accompanying drawings, in which:

FIG. 1 is a longitudinal section through an engine;

FIG. 2 is a section taken along the line II of FIG. '1',

FIG. 3 is .a view taken along the line III-II of FIG. 2;

FIG. 4 is an exploded perspective view of the baffie means.

The engine represented in the drawings comprises a crankcase 1 that carries the drive shaft 2 and supports at its top the cylinder 3; in the case of the drawing, those cylinders are two in number but, as is evident, a greater number of cylinders in line does not involve any substantial variant from the point of view of the present invention, the case of two cylinders having been chosen for the only purpose of greater simplicity of representation.

The pistons 4 slide in the cylinders 3. Wrist pins 5 are pivoted to the connecting rods 6 which actuate the drive shaft 2, all that being conventional. The crankcase 1 is extended upwards by the walls 7 which confine a space open upwards wherein the cylinders 3 are accommodated the external surface of which is provided with iins 8 lying in planes passing through the axis of the respective cylinder.

The head of each cylinder comprises a part 9 in the shape of a disc of comparatively thin thickness rigid with or integral with a plurality of fins 10 lying in planes substantially vertical and rigid or integral in turn with a part 11 of generally ring shape, havng an axial dimension with respect to the cylinder substantially greater than the thickness of the part 9 mentioned above and a diameter corresponding generally with the diameter of the cylinder. The ring part 11 is pierced by four bores through which four bolts 12 pass which secure the head to the upper mouth of the cylinder 3.

The explosion pressure that is exerted upon the lower, face of the part 9 of the head is supported or backed up by a sufficiently great number of fins 10, thus the part 9 may have, as said, a comparatively thin thickness; the fins 10 then transmit the axial strain to the part 11 which distributes it to the bolts 12 which are anchored to the crankcase 1 in a conventional manner not shown in the drawings. The annular structure 11, having a compara tively great thickness, is adapted to distribute without any apreciable deformation the reaction of the bolts 12 onto the plurality of fins 10.

As is seen in the drawings the

parts

9 and 11 of the head are spaced from each other in the axial direction by a certain distance, so that the whole wall of the head parallel to the axis of the cylinder presents a plurality of apertures separated from one another by the fins 10 and by the other parts to be mentioned hereinafter, which apertures are all in communication with the central upper aperture of the ring part 11 of the head.

In the part 9 of the head there are provided the suction innin s 3 ports and exhaust ports wherein the

respective valves

13 and 14 seat and which are in communication with the

respective channels

15 and 16. The axes of the aforesaid apertures and of the

respective valves

13 and 14 are preferably in a plane normal to the drive shaft 2 and the axes of the suction channels 15 and exhaust channels 167 are also in that plane or at any rate little spaced apart therefrom. As a consequence the part of the suction and exhaust conduits which lies immediately above the part 9 of the cylinder head between the latter and the aforesaid part 11, is of quite limited length; this circumference is very important mainly with respect to the exhaust conduit because then a correspondingly small part of the exhaust conduit which is in direct contact with the head and the projection thereof in the direction of the axis of the cylinder intersects the central aperture of the annular part 11, for the reasons which will be more fully explained hereinafter.

The above described head comprises also a part projecting upwards, as indicated in the drawings by 17, which carries the spindle 18 of the rockers 19 and 20' which control the movement of the stems of the

valves

13 and 14, against the reaction of the springs 21, under the control of the

respective pushers

22 and 23 governed by the cam shaft 24, all in a known manner and, therefore, represented merely in a diagrammatical way in the drawings. At 25 there is represented a cover which encloses inside it the part 17, the

rockers

19 and 20 and the members adjacent thereto in such a way as to provide lubrication thereof in conventional manner.

It is important to note for the purposes of the present invention that the projection in the direction of the axis of the cylinder of the

rockers

19 and 20 and of the casing 17 that contains them substantially coincides with the analogous projection of the suction and

discharge conduits

15 and 16.

At 26 there is indicated the plug or the injector may position in which the spark be located in such an engine according to the cycle with which the engine operates.

The whole upper part of the crankcase 1 is covered by a sheet metal cap 27 including a baffle means 28, 28' that with cap 27 forms a cooling air passage directing the air from fan 29 over the valve rockers to the ring parts 11 of the cylinder heads; this baflie means 28, 28" is provided with apertures corresponding to the central cavities of the aforeside ring parts 11.

The cap 27 then presents an opening in communication with the space that is above the bafiie means or

diaphragm

28, 28' in which opening a fan 29 is mounted controlled in any manner, for instance by means of the transmission 30 actuated by the drive shaft 2.

The upper walls 7 of the crankcase 1 finally present apertures 31 in communication with the outside, at the lower part of the space surrounded by said wall and enclosing the cylinders.

In an engine as above described the air fan 29 into the space enclosed by the cap 27, is blown through the central openings of the parts 11 of the cylinder heads; that air is not yet heated up, so it cools the fins 10, the very short section of conduit of discharge 16 and the comparatively thin portion 9 of the head, finding wide passage in this path owing to the arrangement, as above explained, in connection with the

rockers

19 and 20 and with respect to the

conduits

15 and 16. In that way a vigorous cooling of the head is obtained with a comparatively moderate delivery of air.

The cooling air blown into the ring part 11 issues below it from the apertures bounded by the fins 10 and follows a path at considerable speed along the walls of the cylinders 3 that are provided with fins 8, thereby coolring the walls of the cylinders, and is discharged to the atmosphere through the apertures 31.

In addition to realizing this effective air-cooling, the engine above described affords other considerable advantages. The Walls 7 that enclose the space containing the blown by the cylinders constitute also two sturdy lateral ribbings which reinforce the structure of the crankcase 1. It is interesting to observe that an air-cooling by means of ventilation eifected in a direction transverse to the axis of the cylinders as is used in many cases, requires discontinuity of walls such as the Walls 7; the weakening of the framing of the engine that is caused thereby then compels nibbings or other reinforcing structures to be used in the lower part of the engine thereby complicating the structure and making the construction heavy.

The course of the air in a direction substantially parallel to the axis of the cylinders utilizes the low temperatures of the fresh inlet air for the cooling of the head, which supplies the maximum part of the heat to be dissipated by cooling, while it utilizes the air ata slightly higher temperature for the cooling of the cylinder walls which have to dissipate a much smaller amount of heat. This circumstance provides a utility in the starting period of the engine, during which the cylinder walls do not need any vigorous cooling but can utilize instead a diminished dissipation of heat due to the presence of the slightly heated-up air which runs along their finned surface.

Another important advantage attained by an engine as above described derives from the fact that the cooling air always circulates between walls as far as the outlet from the mouth 31; if then at those months there is available a conduit adapted to capture the heated air leaving them to convey it to a suitable place, for instance out of the engine room, it is possible to realize the cooling without over-heating the engine room and without the necessity of enclosing the engine in a special casing as was attempted previously, in order to eliminate the undesired consequences deriving from the impossibility or difliculty of removing the heated cooling air.

Finally another advantage lies in the substantial diminution of noise which an engine so built affords by virtue of the acoustic insulation of the mechanical parts from which the noise arises, due to the presence of the walls 7 and of the cap 27 which completely encase said parts.

The structure of the cylinder heads above described finally permits different thermal expansions of the various parts of said head Without involving excessive mechanical stresses in the material. a 1

We claim:

1. Internal combustion engine having at least one cylinder and having suction and exhaust valves and having rocking levers to operate such valves and having air cooling, in which the cooling air under fan pressure is blown parallel to the axis of the cylinder from the head downward, while the axes of the suction and exhaust valves, the rocking levers controlling said valves and the axes of the suction and exhaust valves lie substantially above said cylinder in a common plane parallel to the axis of the cylinder, characterized by a cylinder head including a relatively thin portion closing the cylinder, a generally ring-shaped portion of a diameter substantially the same as the diameter of the cylinder and surrounding said valve axes and lying parallel to and at a distance from said relatively thin portion, a plurality of circumferentially spaced radially extending tins extending from said thin portion to said ring-shaped portion connecting said ringshaped portion and said thin portion together and to provide cooling air passages through said ring-shaped portion and between said fins, and means securing the cylinder head to said engine.

2. Internal combustion engine as claimed in claim 1, characterized by the fact that said plane is substantially perpendicular to the crankshaft.

3. Internal combustion engine as claimed in claim 1 characterized by the fact that the cylinder head is cast in one piece.

4. Internal combustion engine as claimed in claim 1 characterized by the fact that the cylinder head is made of one piece of cast iron.

5. Internal combustion engine as claimed in claim 1 characterized by a plurality of cylinders arranged in a row enclosed in a space delimited by lateral walls parallel to the axes of the cylinders and provided with apertures for the outlet of cooling air near the bases of the cylinders.

6. Internal combustion engine as claimed in claim 5, characterized by a cover enclosing the upper part of said space, a baflie means under said cover to provide a closure for the lower side of said cover and provided with apertures corresponding to the aforementioned annular portions of the cylinder heads whereby the sole passages for outflow of cooling air from said cover is through said generally ring-shaped portion and between said fins and a fan for blowing air under said cover above said diaphragm.

7. In an air-cooled internal combustion engine having a crankshaft and in which the trend of the cooling air stream is substantially parallel to the axis of the engine cylinder, and directed from the head to the cylinder, a cylinder head comprising a cover member for closing the upper end of the cylinder provided with intake and exhaust ports, a member of generally ring shape to provide passage for downward flow of cooling air toward said cover member With passages to accommodate bolts for securing the engine head to the cylinder block, and a plurality of vertical, radially and axially extending spacedapart fins integral with said circular cover member and with said annular member for providing axial connection between said cover member and said member of generally ring shape to provide a plurality of generally radially extending airflow passages between said radially spaced apart fins.

8. The device of claim 7 in which valves are provided for inlet and exhaust and operating means including valve stems and rockers are mounted on said cylinder head, said rockers lying substantially above said ring-shaped portion and said valve stems extending through said ringshaped portion, whereby said valve stems and rockers are cooled by air.

References Cited in the file of this patent UNITED STATES PATENTS 835,277 Prayer et al. Nov. 6, 1906 1,491,584 Connor Apr. 22, 1924 FOREIGN PATENTS 519,626 France Jan. 27, 1921 971,175 Germany Jan. 8, 1959

Claims

1. INTERNAL COMBUSTION ENGINE HAVING AT LEAST ONE CYLINDER AND HAVING SUCTION AND EXHAUST VALVES AND HAVING ROCKING LEVERS TO OPERATE SUCH VALVES AND HAVING AIR COOLING, IN WHICH THE COOLING AIR UNDER FAN PRESSURE IS BLOWN PARALLEL TO THE AXIS OF THE CYLINDER FROM THE HEAD DOWNWARD, WHILE THE AXES OF THE SUCTION AND EXHAUST VALVES, THE ROCKING LEVERS CONTROLLING SAID VALVES AND THE AXES OF THE SUCTION AND EXHAUST VALVES LIE SUBSTANTIALLY ABOVE SAID CYLINDER IN A COMMON PLANE PARALLEL TO THE AXIS OF THE CYLINDER, CHARACTERIZED BY A CYLINDER HEAD INCLUDING A RELATIVELY THIN PORTION CLOSING THE CYLINDER, A GENERALLY RING-SHAPED PORTION OF A DIAMETER SUBSTANTIALLY THE SAME AS THE DIAMETER OF THE CYLINDER AND SURROUNDING SAID VALVE AXES AND LYING PARALLEL TO AND AT A DISTANCE FROM SAID RELATIVELY THIN PORTION, A PLURALITY OF CIRCUMFERENTIALLY SPACED RADIALLY EXTENDING FINS EXTENDING FROM SAID THIN PORTION TO SAID RING-SHAPED PORTION CONNECTING SAID RINGSHAPED PORTION AND SAID THIN PORTION TOGETHER AND TO PRO-