Internal Combustion Engine

The invention relates to an internal combustion engine which may be internally or externally ignited and may be supplied with a combustible fuel-air mixture in any known and suitable manner, for example by carburetion or by fuel injection. The engine may be of the 4-cycle type, performing successive intake, compression, power and exhaust strokes.

In known 4-cycle engines of this type, a sliding or rotating and sliding piston compresses a fuel-air mixture in a combustion chamber. The sliding friction between the piston or piston seals and the cylinder wall is reduced by continuous lubrication requiring extensive auxiliary equipment e.g. an oil sump, an oil pump, multiple conduits, etc. In addition, the compression seal of such an engine is always imperfect, even when all parts are new, and gradually deteriorates even further due to wear. Furthermore, oil leaking into the combustion chamber produces smoke and other harmful substances which are vented to the atmosphere.

It is a principal object of the invention to provide an internal combustion engine in which any sliding friction is reduced substantially, thus obviating cylinder wall lubrication.

It is another object of the invention to provide an internal combustion engine with permanent seals which are not subject to leakage due to wear.

Yet another object is to provide an engine with few parts and of relatively inexpensive construction. These and other objects are attained, briefly stated, by providing a rigid wall, at least part of whose surface is curved. Advantageously, the curved portion of the wall surface is toroidal, i.e. portions of the wall correspond to surfaces of a torus. The wall may encompass a substantially complete torus or only a portion thereof. In particular, the toroidal surface is not limited to having one or more circular crossections. The central region of the wall may extend substantially cylindrically in the axial direction and this region is terminated by a dome or head portion which, in known manner, includes valves and, usually, a spark plug. Attached to the rim of the rigid wall is a flexible curtain which substantially conforms to the surface contour of the rigid wall but which, due to its inherent elasticity, can be pulled away from the wall, thereby forming an intervening space. During the approach of the curtain to the wall, gas is forced out of the intervening space into a central space which forms the main combustion chamber where ignition takes place and from which spent gases are exhausted. The central base of the curtain is connected to a crankshaft or other suitable motion converter means. Valve timing is performed in known manner in synchronism with the crankshaft rotation.

The invention will be better understood as well as other objects and advantages thereof become more apparent from the ensuing detailed description of two preferred embodiments, taken in conjunction with the drawing.

FIG. 1 is a sectional side view of the main elements of an engine according to the invention;

FIG. 2A is a partial top view of the engine of FIG. 1 showing a first embodiment of the curtain;

FIG. 2B is a similar view as in FIG. 2A, showing a second embodiment of the curtain.

Turning now to FIG. 1, there is shown a substantially toroidal wall 1, preferably made of cast, forged or machined metal parts, the metal being, e.g., aluminum, iron, steel or some suitable alloy. The wall 1 has a central head portion 1A. The wall 1 may be a full torus, substantially as shown, i.e. closed onto itself in the manner of a doughnut, or it may be partially incomplete, in the manner of a sliced bagel. The large central radius R may be constant, as shown in FIG. 2 or it may vary, thus making the planar crossection non-circular. Similarly, the small radius r may be constant over azimuth and altitude or it may vary in either parameter. The hollow interior of the wall 1 may carry coolant, admitted and returned through openings 2. Annularly attached and sealed to the outer surface of the wall 1 is a curtain 3 which is flexible and which has a natural, unstressed shape similar to that of the wall 1. This curtain may be a single, metallic sheet 4 or a single, molded shell of synthetic material, possibly reinforced with glass or metal fibers. Preferably, the curtain includes a blanket 5, made from one or more layers of a rubber-like material which can be reinforced in known manner, e.g. with steel mesh 6. Preferably, the blanket 5 is so made and attached that it is able to provide hermetic pressure sealing of the interior volume. For this reason, the metal sheet 4 may suitably consist of several, preferably overlapping sectors 4A which serve to shield the blanket 5 from heat and/or chemical reaction with combustion gases and which can transfer heat to the wall 3 during periods of contact. The head portion 1A includes, in known manner, an intake valve 7, an exhaust valve 8, a spark plug 9 and suitable intake and exhaust channels leading to, e.g. a carburetor and to a muffler, respectively (neither shown). Attached to the base portion of the curtain 3 is a suitable block 10 serving as attachment point for the camshaft lobe 11, possibly via a connecting rod 12. A crankshaft 13 may be of any suitable construction. Suitable known means 14, e.g. belts or gears, transfer rotary motion to cam-shafts 15 or the like which actuate the valves 7,8 in the proper sequence. The operation of the described engine is as follows: During a downward stroke (as seen in the figure) of the block 10, the curtain 3 is pulled away from the wall 1, thereby increasing the space between the curtain 3 and the wall 1. The ensuing vacuum pulls in a quantity of combustible mixture through the valve 7 while the valve 8 is closed. The valve 7 then also closes. The block 10 now moves the curtain toward the wall 1 with the result that gas is forced from in between the approaching surfaces as indicated by the arrows. Thus, the vapor is compressed and is also given momentum toward the central chamber 16. The collision of radially approaching gases induces turbulence which enhances combustion. At the instant of ignition by the spark plug 9, the curtain and the wall 1 are in very close contact, thereby excluding from the space between them virtually all combustible vapor. Thus, the combustion of gases takes place entirely in the central volume 16. The closely adjacent surfaces of the wall 1 and the curtain 3 effectively prevent the combustion shock wave from propagating beyond the volume 16. When the block 10 moves downwardly, the space between the wall 1 and the curtain 3 is increased smoothly and gradually while the combustion chamber pressure drops rapidly. Thus, the resilient curtain is able to contain the instantaneous pressure without being damaged. On the return stroke, the valve 8 is opened, permitting spent gas to be exhausted through the valve 8, in known manner, through a muffler (not shown) to the atmosphere. The large cooling surface of the wall 1, which makes intimate periodic contact with the curtain 3 insures good heat transfer out of the combustion chamber.

In an alternative embodiment of the curtain, shown in FIG. 2B, the inner surface of the blanket 5 is studded with a plurality of embedded pads 17, e.g. ceramic, metal or graphite pads for the purpose of protecting the underlying blanket 5 from heat and/or chemical reaction. These pads may overlap and/or interlock to form a substantially continuous surface and their function is similar to the sheet sectors 4A in FIG. 2A. If necessary, additional coolant may be circulated through channels 18 in the blanket 5, and the pads 17 may extend into the coolant channels 18 to further enhance the heat transfer process as shown at 17'.

It is to be understood that the foregoing description of preferred embodiments is given entirely by way of an illustrative example and that numerous variants of the invention may be described without departing from the scope of the invention which is defined in the claims.