Piston ring for piston engines

The invention relates to a slot piston ring (1) for the pistons of internal combustion engines or compressors, having a peripheral recess (9) (a so-called scraper ring) that extends close to the slot (2) on the external periphery (3) of the piston facing away from the combustion chamber. The aim of the invention is to reduce oil consumption and the amount of leakage gas of such a piston. To this end, the recess is configured to extend from a zone (10) diametrically opposite the slot, starting with a maximum height (12) which gradually decreases to zero (13) in the direction of the slot or close to the slot.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicant claims priority under 35 U.S.C. §119 of German Application No. 100 44 241.2 filed Sep. 7, 2000. Applicant also claims priority under 35 U.S.C. §365 of PCT/DE01/02644 filed Jul. 11, 2001. The international application under PCT article 21(2) was not published in English.

The invention relates to a slot piston ring for pistons for internal combustion engines or compressors.

Such a piston ring is known from CH-PS 171 815. In connection with the piston ring shown there, provision is made on the side facing away from the combustion chamber on the external peripheral surface (running surface) for a groove-like recess that extends fully around up to close to the site of the slot in order to obtain a rectangular ring gap. Such a recess for a so-called nose ring is produced by milling. Such a piston ring is not readily satisfactory with respect to lubricant consumption and the passage of leakage gas.

Therefore, the problem of the present invention is to find a piston ring that assures a low consumption of oil and only minor passage of leakage gas in the presence of adequate lubrication conditions, and that can be manufactured at favorable cost.

The solution to this problem is obtained with a piston ring having a recess configured to extend from a zone diametrically opposite the slot with a maximum height gradually decreasing to zero up to or near the slot.

Advantageous further developments according to the invention are discussed below.

A piston ring1with the slot2that is simultaneously acting as a compression and oil-stripping ring has a recess4on its external side3facing away from the combustion chamber. In the prior art, according toFIG. 1, said recess is extending all around like a groove up to the ends5,6of the piston ring near the slot2at a uniform height7.

In connection with a piston ring8as defined by the invention according toFIGS. 2 to 4, which is designed in the form of a nose groove ring, a corresponding recess9is extending starting from a zone10diametrically opposite the slot or gap side11at a maximum level12up to the slot2or gap side11, gradually decreasing to zero13. The course of the level of the recess9is indicated in the drawing by a dotted line.

Such a recess9is produced on the piston ring8shown by a simple turning process, in which the piston ring8is chucked inclined in its receptacle, so that the corresponding cut is produced in the conventional manner opposite the gap side11, but decreases to zero diametrically opposite the gap side11.

The embodiment of the piston ring shown inFIG. 3is different from the one shown inFIG. 4in that the recess9is realized in one embodiment (FIG. 3) with a rounded shape (nose14), and in the other embodiment with a rectangular shape15(FIG. 4).

Such a nose or grooved nose ring can be employed in connection with pistons for internal combustion engines or compressors in the ring groove one of the piston, on the one hand, and/or in the ring groove two of the piston on the other hand. It has been found in this connection that as compared to conventional embodiments, it was possible to distinctly reduce the oil consumption, on the one hand, and the passage of leakage gas (blow-by) on the other hand, depending on in which location it is used. Therefore, it can be noted that with such a piston ring, it is possible in a manner that is simple both in terms of construction and manufacture to provide a piston ring for the piston of an internal combustion engine or a compressor with which excellent results are achieved with respect to the passage of leakage gas and oil consumption in the presence of adequate lubrication conditions.