US2179683A - Internal combustion engine - Google Patents

Description

NOV. M, 1939.

C. BREBECK INTERNAL COMBUSTION ENGINE Filed April 18, 1938 3nnentor Cinornegs 1 Patented Nov. 14, 1939 I UNITED STATES PATENT OFF ICE INTERNAL COMBUSTION ENGINE Charles Brebeck, Herkimer, N. Y. Application April 18, 1938. Serial No. 202,725

5 Claims.

This invention pertains to internal combustion engines and more particularly to engines of the two .cycle type.

In any internal combustion engine cylinder, injurious temperature stresses may be caused by injudicious distribution of metal, particularly atslightest distortion of the cylinder affects such an engine seriously, making starting difiicult and causing impairment of operating emciency. For

these reasons it is important, in the case of small one-piece cylinders to produce a symmetrical design, at vleast as far as the combustion chamber and the adjacent parts are concerned.

It has been customary among miniature engine designers'to follow designs of larger engines. these designs the cylinders are secured at their lower ends to the crank cases. Ports and transfer passages are formed in members either cast,

welded, brazed, soldered, or clamped onto thecylinder barrel. These methods of forming ports and passages set up stresses which cause cylinder distortion and unevenness of wall thickness.

The use of cast iron for small engines is unsatisfactory because of casting difficulties. The location of a portion of the firing chamber within the crank case may result in undersirably high crank case temperatures, and .in localized' hot spots which cause cylinder and crank case distortion. Where aluminum or aluminum alloy'crank cases are used with iron or steel cylinders the unequal rates of expansion of the two metals may cause separation between the cylinder and crank case. ,This may result in exhaust gases entering the crank case and causing an explosion; or in gas charges seeping out of the exhaust port and in any event invites corrosion of the metals where they overlap. The parts may even be corroded in such a way as to cause seizure between the cylinder and crank case, and to prevent disassembly without breakage, especially where, as in miniature engines, the metal sections are thin.

I have found after intensive study of the subject that for the above reasons practices followed in making large engines cannot be followed in making miniature engines, and hence that factors which were relatively unimportant in large engines become highly important in miniature designs, and constitute the difference between success and failure in making engines of the latter type.

Accordingly the main object of my invention is to produce an internal combustion engine in 5 which the heat transfer surfaces are symmetrically arranged; in which maximum strength of parts may be obtained in parts of small section, and to generally modify and improve the structure and operation of engines of the two-cycle 10 type.

Other objects and advantages will appear from the following specification when read in" connection with the accompanying drawing in which:

Figure 1 is a vertical axial section of one form of internal combustion engine embodying the present invention; and

Figure 21s a section on line 2-2 of Fig. 1 illustrating the heat transfer conditions as they 20 are approximated in engines embodying the invention.

In the drawing, I represents the cylinder, which is preferably manufactured by machining from a solid bar of steel. This method of manufac- 25 ture makes it possible to produce a cylinder wall of thin uniform section throughout, and to obtain symmetry and'strength which cannot be attained with cast metal, particularly where the parts are small. Fins 3 are formed on the cylinder to aid 30 in dissipating heat therefrom to the surrounding air, and a tapped hole t is provided for a spark plug (not shown). From the lower half of the cylinder and integral with it extends a .peripheral mounting flange 5, which is in a plane 35 perpendicular to the axis of the cylinder I.

I locate the exhaust port 6 above the flange 5,. and hence, above the top of the crank case extension so that exhaust gases do not come into contact with the crank case as they do in other 40 engines of similar design. This exhaust port,. being in the part of the cylinder outside the crank 'case extension, is in close proximity to the cooling having the exhaust port 8 above the mounting flange Band, therefore, the firing chamber entirely above the flange, a greater portion of the cylinder is external tovthe crank case. 'Hence, 55

I am enabled to have more space covered by cooling'flns 3 on the cylinder than can be covered on a cylinder of the same size where the exhaust port is below the mounting flange.

The mounting flange 5 may be ground to fit closely on the upper surface of an extension of the crank case 8 or, as shown in the drawing, such surfaces may haveinterposed between them a gasket l5 of suitable material, such as asbestos, copper, or the like. The crank case 8 is preferably made of aluminum or aluminum alloy so that it will be of minimum weight. The cylinder I flts within the extension of the crank case so that intake port II is opposite crank case intake passage I, and transfer port 8 connects with,

channel I ii in the crank case. Transfer port 9 is formed of openings in the wall of the cylinder and grooves in the under side of flange I, the bottom of thegrooves being above the lower edge of said flange and below the top edge of said flange. The plane passing through the top of the flange is, therefore, above the transfer port and below the exhaust port. This brings the tops of the transfer ports Sand the .bottoms of the exhaust ports 6 into very close relationship axially (Fig. 1), so that the baiile I! carried by the head of piston I2 can be made of a minimum height for most eflicient operation.

This relation of the ports 6 and 9 makes it possible to produce, if desired, both a transfer port and an exhaust port by a single drilling, or equivalent, operation and at the same time gives the transfer ports the upward inclination indicated in Figs. 1 and 2. This inclination functions to direct the entering gases upwardly into the combustion chamber, thus promoting turbulence in the charge and assisting in the rapid and thorough expulsion of the exhaust gases. The piston l2 carries the usual piston rings l8. In attaching the cylinder I to the crank case 8, the only securing means necessary are capscrews which are passed through holes I6 in the mounting flange 5 and into recesses tapped in the crank case. No clamps, lugs, or other projections are used or are necessary, and since there are no ports formed in parts attached to the cylinder, each port being merely a plurality of holes in the cylinder wall, the mass of metal of the cylinder is evenly distributed and no distortion is caused by hot spots.

In a miniature light weight engine, the lateral thrust of the piston may be sufllcient to bend the cylinder slightly, and thus to lead to breakage. When, e. g., the crank I! is horizontal, the lateral thrust of the piston l2 will be greatest. As

shown in dotted lines in Figure 1, when the crank is horizontal, the piston is in such a position that its wrist pin It will be in substantial alignment with the mounting flange I. The cylinder is thus strengthened, and'indeed supported, at the point of its maximum lateral stress.

Referring to Figure 2, I shall now describe the eflect of heat on the expansion of the metal of the improved cylinder. When a mass of metal in a particular portion of a cylinder is heated, it expands a definite amount. Unless this .expansion is counteracted by an equal expansion of the metal in the area opposite, distortion of the cylinder results. In order that expansion on opposite sides of the cylinder may be the same, it is necessary that the masses of metal in all opposite areas be the same. It is plainly evident that in this cylinder the mass of metal indicated by arrow a is equal to that at a, and similarly b and b, and c and c' represent respectively equal and opposite cylinder masses. In the case of areas a and d, transfer port 9 comprises sections cut out of the cylinder wall and the flange 5 opposite the exhaust port 6 and the intake port H, the latter being shown only in Figure l.

The mass of metal removed in forming port 8 is substantially equal in amount to that removed in forming both exhaust port 6 and "intake port pressure and a charge will be drawn in. Shortly after piston I2 starts its downward travel the skirt of piston l2 will close intake port H, and the mixture of gases in crank case 8 will be partially compressed, Near the lowermost position of piston l2, exhaust port 6 will begin to open and as the piston moves farther downward, transfer port 8 will be uncovered, admitting the compressed mixture from crank case 8 to cylinder I. This mixture enters the cylinder at a high rate of speed and is directed upwardly along the side of the cylinder by baffle it which forms a part of the piston head. Scavenging of the burnt gases will take place as the piston starts its upward travel and as the fresh charge enters. The upstroke of piston I2 will compress the gas in cylinder I. The charge will be flred by a conventional ignition system when the piston is in its uppermost or firing position, and this firing will drive the piston downward to start another cycle.

It will be obvious from the above description that I have produced an engine of simplicity and emciency, free from bolted, welded or brazed manifolds or the like, and capable of production in miniature without the failures and defects of prior .art engines of this class. While the invention has been described as embodied in a miniature engine to which it is especially applicable, it is to be understood that the novel features may be applied to an engine of any size and that while I have shown and described only one specific embodiment, it is obvious the invention may take other forms within the scope of the claims without departing from the spirit and scope of my invention.

What is claimed is:

1. An internal combustion engine of the crank case compression type, including a cylinder with exhaust ports and a piston enclosing a working space; a crank case communicating with said working space through a transfer port in the cylinder and controlled by the piston; a crank and a connectig rod, the parts being so constructed and arranged that the cylinder has an external flange approximately in the plane of the lower limit of the working space, saidflange resting on the crank case, the transfer ports being formed in the lower face of the flange and the exhaust ports being adjacent the upper face of the flange.

2. An internal combustion engine of the crank case compression type, comprising a crank case having a cylinder supporting portion thereon, said portion having an inlet passage to said crank case and a transfer passage; a cylinder having a peripheral mounting flange resting upon said portion with a substantial portion of said cylinder depending within said portion, said cylinder having a transfer port on the lower side or said flange connected to said transfer passage and an exhaust port on the upper side of flange, said ports being substantially coaxially related; and a piston movable in said cylinder and enclosing the working space therein.

3. An internal combustion engine of the crank case compression type, comprising a crank case having a cylinder supporting extension thereon, said extension having an inlet passage to said crank case and a transfer e; a cylinder having a peripheral mounting flange resting upon said extension with a substantial portion of said cylinder depending within said extension, said cylinder containing a plurality of transfer ports below said flange and communieating with said transfer and a plurality of exhaust ports above said flange, said exhaust ports being substantially coaxially related to corresponding ones of said transfer ports; and a piston movable in said cylinder and enclosing the working space therein.

4. An internal combustion engine of the twocycle type comprising a crank case including an open-endedextsnsionhavinganinletportand a transfer passage: a cylinder having a peripheral mounting flange resting on said extension with a substantial portion of the cylinder de- Pending within said extension. said cylinder containing at least one transfer port formed in the bottom face of said flange and inclined to the axis of the cylinder, said port connecting said cylinder to said transfer e, and said cylinder having at least one exhaust port formed therein at the upper face of said flange and substantially coaxial with said transfer port; and

a piston with a bailie thereon movable in said.

cylinder.

case having a cylinder supporting extension; a cylinder carried by said extension and having a skirt projecting within said extension; and a mounting flange on the cylinder substantially midway between the cylinder ends and resting on said crank case extension, said cylinder having an exhaust port above the flange in a position to be isolated from the crank case by said flange, and atransfer port at the lower face of said flange inclined to the cylinder axis and substantiaily coaxialiy related to the exhaust CHARLES

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