Internal combustion engine has a flow path which terminates in an outlet opening in the region of the wall of a piston

The invention relates to an internal combustion engine with at least one cylinder in which two pistons oscillating in opposite directions are arranged.

Opposite piston engines are well known, for example from DE 27 04 006 A1 or DE 1 942 007 A.

Opposite piston engines have the advantage of good mass balance. Since the combustion chamber is formed between the two piston heads, a cylinder head acting as a cooling surface can be dispensed with, whereby a very good thermal efficiency can be achieved.

Wall deposits, in particular in the piston top land area, however, have an adverse effect on the combustion process and the consumption of lubricating oil.

DE 863 870 C1 describes an opposed piston internal combustion engine with cooled liners inserted into its cylinders. A fire ring is not provided.

From EP 1 061 294 A2 an internal combustion engine is known in which in the area of ​​the top dead center position of the piston in the cylinder a cylindrical fire ring arrangement with two separate

Rings of fire is arranged. Such a fire ring arrangement without a slot is less suitable for opposed piston engines.

The object of the invention is to avoid these disadvantages and to reduce deposits and the consumption of lubricating oil in an opposed piston internal combustion engine of the type mentioned at the beginning.

According to the invention, this is achieved in that a substantially cylindrical fire ring is arranged in the cylinder in an area associated with the top dead center position of the pistons, the inner diameter of which is preferably smaller than the diameter of the cylinder and that the fire ring is slotted. The slotted design of the fire ring enables easy insertion into the cylinder, which is preferably formed by a cylinder liner. The width of the fire ring is dimensioned so that the top lands of the pistons dip into the fire ring at top dead center, whereby deposits are removed or avoided.

It is preferably provided that the fire ring is inserted into an annular recess in the cylinder jacket.

A marking of the slot on the piston when the piston travels over the fire ring can be avoided if the slot is inclined, ie inclined to the cylinder axis.

The fire ring is preferably arranged in the cylinder so that it cannot twist and is preferably held by a twist lock. It can be provided that the anti-rotation device of the

Fire ring is formed by a screw or a pin which preferably engages in the slot and is inserted into the cylinder. It is particularly advantageous if the twisting shear is inserted into the slot and the diameter of the screw completely fills the width of the slot. In this way, twisting of the fire ring and accidental falling out can be prevented.

In a further embodiment of the invention it can be provided that the fire ring has at least one passage opening for a component opening into the combustion chamber, the component preferably being an injection nozzle, an antechamber nozzle or a spark plug. Injection nozzles, prechamber nozzles and / or spark plugs can thus protrude through the fire ring into the combustion chamber defined by the fire ring.

AT 414 016 Β

The invention is explained in more detail below with reference to the figure.

The figure shows a cylinder of an internal combustion engine according to the invention in longitudinal section. In a cylinder 4, formed by a cylinder liner 2, of a counter-piston internal combustion engine, two pistons 6, 8 oscillating in opposite directions synchronously are arranged. The pistons 6, 8 are connected via a connecting rod (not shown) to a respective crank mechanism (not shown), the crank mechanisms being synchronized with one another. The figure shows the two pistons 6, 8 in the top dead center position, in which the pistons 6, 8 experience the closest approach. In the area of ​​the space between the two pistons 6, 8 defining a combustion chamber 10, a fire ring 12 is arranged, the fire ring 12 being inserted in an annular recess 14 of the cylinder liner 2, which is preferably formed by an undercut. The inner diameter d of the fire ring 12 is smaller than the diameter D of the cylinder 4.

The fire ring 12 has a slot 18 inclined to the cylinder axis 16, whereby the diameter of the fire ring 12 can be slightly elastically reduced during assembly in order to enable it to be pushed into the cylinder liner 2 until the fire ring 12 engages in the recess 14.

The fact that the slot 18 is designed obliquely to the cylinder axis 16 prevents the slot 18 from being marked when the pistons 6, 8 are driven over.

In order to prevent the fire ring 12 from twisting, it is arranged in the cylinder liner 2 so that it cannot twist. This prevents the fire ring 12 from rotating, as well as an unintentional reduction in the inner diameter of the fire ring 12 and thus an unintentional falling out of the cylinder liner 2.

The fire ring can have at least one radial recess 22 for an injection nozzle, an antechamber nozzle or a spark plug.

The fire ring can very effectively prevent so-called borepolishing through deposits and achieve a reduction or long-term stabilization of the lubricating oil consumption.