Internal combustion engine

The invention concerns a combustion engine comprising a cylinder and a piston which is displaceably guided in the cylinder, the piston having a piston head facing a combustion chamber and being coupled to a crankshaft via a connecting rod, wherein a second piston which is displaceably guided in the cylinder is provided opposite to the piston, the second piston also having a piston head, wherein the combustion chamber is disposed between the two piston heads, and the second piston is coupled to a crankshaft via a connecting rod.

BACKGROUND OF THE INVENTION

The invention concerns an internal-combustion engine with a cylinder and a piston which is displaceably guided in the cylinder, the piston having a piston head facing a combustion chamber and coupled to a crankshaft via a connecting rod.

Engines of this type have been known for more than a hundred years and are used as stationary drives as well as for vehicles. The cylinder in these combustion engines is closed on one side with a cylinder head and, on the other side, a piston is moveably guided in the cylinder to transfer the driving force to a crankshaft via a connecting rod as the combustion gases expand. Combustion engines operating according to this principle may function in two cycles or four cycles, such as Otto and diesel engines. The efficiency of these engines is, however, very low.

It is the underlying purpose of the invention to provide a combustion engine having higher efficiency.

SUMMARY OF THE INVENTION

This object is achieved in accordance with the invention with a combustion engine of the above-mentioned type by providing a second opposing piston, wherein the second piston is displaceably guided in the cylinder and also has a piston head, the combustion chamber being disposed between the two piston heads with the second piston being coupled to a crankshaft via a connecting rod.

In contrast to conventional combustion engines, the inventive combustion engine does not have a cylinder head, rather a further piston, wherein part of the cylinder and the piston heads of the two pistons define the combustion chamber. When the combustion gas is ignited in this combustion chamber, the two pistons are driven in opposite directions, i.e. forced apart, and transmit their motion to the crankshafts via their connecting rods. The gases expanding in the combustion chamber thereby drive not only one but two pistons to substantially increase the efficiency. Moreover, the combustion engine in accordance with the invention has reduced fuel consumption, improved emission values, and is easier to service.

Advantageously, the pistons move simultaneously during expansion of the combustion gases, i.e. the forces and moments generated are largely compensated for. Vibrations are thereby almost completely compensated for, such that special devices such as e.g. balancer shafts etc. are not required.

In a preferred embodiment, the two pistons are disposed at an angle of 180° relative to each other. This means that the two pistons are disposed opposite to each and exercise opposite motions. For this reason, the cylinder may be a simple sleeve.

Alternatively, the two pistons may be disposed at an angle relative to each other which is different from 180°, i.e. the cylinder may have a V-shape. This reduces the size of the engine.

In a particularly preferred embodiment, the upper dead centers of the two pistons have a separation from each other, and the cylinder wall in this region between the pistons may comprise an inlet valve, an outlet valve, a fuel injector and optionally a spark or glow plug. The pistons may also have recesses in the jacket region, which are especially provided for this purpose to prevent them from passing over the cylinder wall in the region of the valves or ignition devices.

In a preferred manner, the combustion chamber is spherical. This is advantageous in that the expansion forces of the combustion gases expand uniformly in all directions thereby uniformly introducing the forces into the pistons.

The piston head is preferably recessed and forms part of the combustion chamber. The depression may thereby be partially spherical, have a different shape, or comprise means for swirling the combustion gases.

50% to 90%, in particular 75% of the combustion chamber is located in the piston head of the two pistons. The rest of the combustion chamber is formed by the region of the cylinder located between the two pistons. If the combustion chamber is spherical, the region of the cylinder located between the two pistons has a partially spherical curvature when the pistons are in the upper dead center. The combustion chamber which is formed by this part of the cylinder and the two piston heads then has a spherical, i.e. ball-shaped design.

The inventive combustion engine may be a two-cycle or four-cycle engine, wherein the Otto principle as well as the diesel principle may be used. In the variant of a two-cycle engine, the piston passes over the overflow channels. Inlet and outlet valves are not provided.

In accordance with the invention, the two crankshafts are coupled to a flywheel e.g. via transmission wheels and rotate in the same direction. The crankshafts may also be coupled to the flywheel using chains or toothed belts.

Further advantages, features and details of the invention can be extracted from the dependent claims and the following description which describes in detail a particularly preferred embodiment with reference to the drawing. The features shown in the drawing and mentioned in the claims and in the description may be essential to the invention either individually or in arbitrary combination.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1shows a side view of a section I—I in accordance withFIG. 4of the combustion engine which is designated in total with10. This section shows the combustion engine10in a highly schematic manner. Many components are schematically indicated, such as e.g. the cylinder12which has substantially the shape of a sleeve and accommodates two pistons14and16which are disposed to be displaceable and movable in opposite directions. These pistons14and16are each mounted to a connecting rod18which is connected to a crankshaft, designated in total with20. The drives22and24for the inlet valve and the outlet valve are also shown. These drives22and24are formed e.g. by camshafts.FIG. 1also shows that the combustion chamber26has a spherical shape.

FIG. 2shows an enlarged view of the spherical combustion chamber26with the two pistons14and16being located at their upper dead center position. It is clearly shown that the spherical shape provided in the wall28of the cylinder12is continued in the piston heads30of the two pistons14and16in that the piston heads30are recessed. The partially spherical region32of the wall28of the cylinder12has one of the two valves, e.g. the inlet valve34, which is also curved in a partially spherical shape. The partially spherical curvature of the region32of the cylinder wall28is continued in the piston head30such that the entire combustion chamber36is substantially spherical. Finally, an injector nozzle60and a spark plug36are indicated inFIG. 2. The spark plug36could alternatively represent a glow plug, should the combustion engine10be operated according to the diesel principle.

FIG. 3shows a gearbox designated with38into which the axes30of the crankshafts20terminate, each carrying a toothed crank wheel42. This toothed crank wheel42mates with a transmission or transfer toothed wheel44which engages a flywheel46. The directions of rotation of the toothed wheels42,44and46are indicated by arrows48.

FIG. 3also shows a toothed wheel50for driving an oil pump (not shown), a toothed wheel52for a water pump (not shown), and a toothed wheel54for a starter (not shown), which all engage the transmission toothed wheels44. Driving toothed wheels56and58for the valve camshaft drives22and24engage the flywheel46.

The forces and moments generated are clearly largely symmetrical due to the symmetric arrangement of the individual components, thereby largely eliminating imbalances and vibrations.

The inventive combustion engine10has a higher efficiency, since the forces generated in the combustion chamber26simultaneously act on not only one, but two pistons14and16, which both drive the flywheel46.