DE102008025681A1 - Piston pin for an internal combustion engine - Google Patents

Abstract

A piston pin with a DLC layer is presented that has less than 1 at% silicon and a hydrogen content of> = 20 and <= 65 at%.

Description

Technical area

The The invention relates to a piston pin for an internal combustion engine.

piston pin serve in internal combustion engines essentially the transmission the movement of the piston on a connecting rod, whose movement in turn is transmitted to the crankshaft. Between the piston pin and the so-called pin bosses of the piston and / or the eye of the Pleuels occurs relative motion. To reduce fuel consumption Thus, the friction is as low as possible in this area to keep. Furthermore, it is always desirable to wear too minimize, and thus reduce the "predation".

State of the art

To For this purpose it is known DLC (diamond like carbon) coatings provided.

This describes the WO 2007/020139 A1 Coatings for pistons and piston rings, which are designed as DLC layer and are always applied by means of an intermediate layer on said components. Further, the coatings may have a hydrogen content of 20 to 30 at% (atomic%).

The EP 1 783 349 A1 describes pistons, piston rings and piston pins with DLC coatings that have hydrogen contents of 20 to 40 at%. However, there is always a significant amount of silicon in the DLC layer.

Presentation of the invention

Of the Invention has for its object to provide a piston pin, in terms of friction and wear properties is improved.

The This object is achieved by the method described in claim 1 Piston pins.

As a result, this has a DLC layer with less than 1 at% silicon and a hydrogen content of 20 at.% or more and 65 at.% or less on. It was found that with such a coating the favorable friction and wear properties the DLC layer maintained even at elevated temperatures can be. It should be noted that the DLC coatings also be referred to as amorphous carbon layers. In terms of on the hydrogen content, initial studies show that the Friction and wear behavior of the coatings at elevated temperatures is improved with increasing hydrogen content. Thus, you can these properties of a piston pin by the invention Coating can be improved, and the tendency to eat can be reduced become.

Prefers is the DLC coating directly on the base material of the piston pin applied. However, especially at a hydrogen content greater than 30 at%, also an intermediate layer between the DLC coating and the base material of the piston, piston ring or piston pin be provided.

When Mechanism of action, however, to which the invention is by no means limited It is worth mentioning that the carbon-hydrogen compounds especially at elevated temperatures are more stable than the carbon-carbon bonds. This becomes the binding interaction with the counter body, so in the case of the piston pin with the pin eyes and / or the eye of the connecting rod, weakened, and the so-called anti-sticking behavior is increasing. It also drops the probability that the DLC layer will be graphitized which is equivalent to a decay of the DLC layer. Furthermore, have first Studies have shown that by the inventive Coating composition also the hardness and the penetration modulus the surface can be increased.

advantageous Further developments of the piston pin according to the invention are described in the further claims.

at In particular, the first studies have a hydrogen content of more than 25 at% in the DLC layer proved to be favorable.

This applies in a special way for a possibly hydrogen content of more than 30 at%. With this feature, combined with the above and / or other features mentioned below is also a piston or piston ring with such a coating, in the case of the piston preferably on the piston skirt to be considered as the subject of the invention.

A Further improvement could also be made for a hydrogen content of more than 40 at%. It is for this Case mentioned that here are favorable properties the DLC coating also for silicon shares of 1 at% or more are expected.

After all is especially in the range of a hydrogen content of more than 50 at% a particular improvement in the properties of the coated Piston pin, piston or piston ring to be expected.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - WO 2007/020139 A1 [0004]
• - EP 1783349 A1 [0005]

Claims (5)

Piston pin for an internal combustion engine with a DLC layer with less than 1 at% silicon and one hydrogen content of ≥20 and ≤65 at%. Piston pin according to claim 1, characterized that the hydrogen content is more than 25 at%. Piston pin according to claim 1 or 2, characterized that the hydrogen content is more than 30 at%. Piston pin according to one of the preceding claims, characterized in that the hydrogen content is more than 40 at% is. Piston pin according to one of the preceding claims, characterized in that the hydrogen content is more than 50 at% is.