EP-4735749-A1 - A PISTON FOR A RECIPROCATING INTERNAL COMBUSTION PISTON ENGINE, A RECIPROCATING INTERNAL COMBUSTION ENGINE AND USE OF SUCH PISTON

Abstract

The disclosure relates a piston (1) for a reciprocating internal combustion piston engine. The piston has a scraper ring groove (2), for receiving an oil scraper ring, the groove (2) extending annularly around a circumference of the piston (1). A receptacle volume (3) is arranged below the scraper ring groove (2), and a receiver conduit (4) extends between the scraper ring groove (2) and the receptacle volume (3), so as to provide fluid communication therebetween. A drainage conduit is provided (5) extending from the receptacle volume (3) towards a bottom (1b) of the piston. Notably, a bottom (3b) of the receptacle volume (3) has an annular inclination towards the drainage conduit (5). During an upstroke of the piston, the inclined bottom of the receptacle volume thrusts lubrication oil residing within the receptacle volume towards the drainage conduit.

Inventors

• OJALA, Sami
• KUITUNEN, Jorma
• BERG, Kim
• NURMI, HANNU

Assignees

• Wärtsilä Finland Oy

Dates

Publication Date

20260506

Application Date

20230627

Claims (15)

1. 1. A piston (1 ) for a reciprocating internal combustion piston engine, said piston being configured to be arrangeable in a combustion cylinder of the engine, such that a top (l a) of the piston faces a combustion chamber, the piston (1 ) comprising: a scraper ring groove (2) for receiving an oil scraper ring, the scraper ring groove (2) extending annularly around a circumference of the piston (1 ); a receptacle volume (3) arranged below the scraper ring groove (2), a receiver conduit (4) extending between the scraper ring groove (2) and the receptacle volume (3), so as to provide fluid communication therebetween, and a drainage conduit (5) extending from the receptacle volume (3) towards a bottom (l b) of the piston, characterized in that a bottom (3b) of the receptacle volume (3) has an annular inclination towards the drainage conduit (5).
2. 2. The piston (1 ) according to claim 1 , characterized by comprising one or more of the following: a plurality receiver conduits (4) extending between the scraper ring groove (2) and the receptacle volume (3), so as to provide fluid communication therebetween, and a plurality of drainage conduits (5) extending from the receptacle volume (3) towards a bottom of the piston (1b).
3. 3. The piston (1 ) according to claim 1 or 2, characterized in that the drainage conduit (5) extends between the receptacle volume and either or both of an internal space of the piston, and an external surface of the of piston.
4. 4. The piston (1 ) according to any of the preceding claims 1 -3, characterized in that the piston being of a boxed -type.
5. 5. The piston according to any of the preceding claims 1-4, characterized in that the piston comprises an internal cooling oil gallery coupled in fluid communication with a cooling oil inlet for capturing a cooling oil stream directed towards the cooling oil inlet from below the piston.
6. 6. The piston (1 ) according to any of the preceding claims 1 -5, characterized in that the piston (1 ) comprises a top portion (1c) and a bottom portion (1d) detachably fixed to each other.
7. 7. The piston (1 ) according to claim 6, characterized in that the receptacle volume (3) is located at interface between the top portion (1c) and the bottom portion (1d).
8. 8. The piston according to any of the preceding claims 1 -7, characterized in that the piston comprises an additional scraper ring groove (6) extending around the circumference of the piston (1 ), wherein the additional scraper ring groove (6) is arranged below the receptacle volume (3).
9. 9. The piston (1 ) according to any of the preceding claims 1-8, characterized by a receiver opening (7) extending through a skirt of the piston (1 ) to the receptacle volume (3), said receiver opening (7) being provided below the oil scraper ring groove (2).
10. 10. The piston (1 ) according to claim 9, characterized in that the receptacle volume (3) extends above the receiver opening (7).
11. 11. The piston (1) according to any of the preceding claims 1 -10, characterized by comprising one or more compression ring grooves (8) above the scraper ring groove (2).
12. 12. The piston (1) according to claim 11 , characterized by comprising one or more of the following: a scraper ring (2a) fitted in the scraper ring groove (2); an additional scraper ring (6a) fitted in the additional scraper ring groove (6), and one or more compression rings (8a) fitted in the one or more compression ring grooves (8), respectively.
13. 13. A reciprocating internal combustion engine, comprising a piston (1 ) according to any of the preceding claims 1 -12 received in a combustion cylinder and mechanically coupled to a crankshaft.
14. 14. The reciprocating internal combustion engine according to claim 13, characterized in that the engine is configured for used with gaseous fuel, such as hydrogen fuel.
15. 15. Use of the piston (1 ) according to any of the preceding claims 1 -14 in operating a reciprocating internal combustion engine with gaseous fuel, such as hydrogen fuel.

Description

A PISTON FOR A RECIPROCATING INTERNAL COMBUSTION PISTON ENGINE, A RECIPROCATING INTERNAL COMBUSTION ENGINE AND USE OF SUCH PISTON FIELD OF THE DISCLOSURE The present disclosure relates to reciprocating internal combustion piston engine, and more particularly to pistons used in such engines. The present disclosure further concerns efficient drainage of lubrication oil recovered from walls of the cylinder. BACKGROUND OF THE DISCLOSURE In conventional reciprocating internal combustion piston engines, excessive lubrication oil is recovered from combustion cylinder walls by scraper rings provided on the piston, so as to prevent lubrication oil from entering the combustion chamber. Lubrication oil contamination in the combustion chamber may lead to premature or irregular combustion and increased emissions. To this end, conventional arrangements include the provision of an receptacle volume on piston below the scraper ring, into which volume excess lubrication oil enters during a downstroke of the piston. Certain arrangements even include a drainage duct for draining the lubrication oil from the receptacle volume back to the crank case. BRIEF DESCRIPTION OF THE DISCLOSURE An object of the present disclosure is to provide for reducing the risk of lubrication oil contamination in the combustion chamber. The object of the disclosure is achieved by a piston for a reciprocating internal combustion piston engine, a reciprocating internal combustion engine, and the use of such piston, which are characterized by what is stated in the independent claims. The preferred embodiments of the disclosure are disclosed in the dependent claims. The disclosure is based on the discovery that insufficient drainage from a receptacle volume results in the lubrication oil splashing within the receptacle volume, or even out therefrom back onto the cylinder wall. The present disclosure aims at improving drainage from the receptacle volume by providing an inclination at the bottom thereof, such that said inclination leads towards a drainage conduit. As a result, during an upstroke of the piston, the inclined bottom of the receptacle volume thrusts the lubrication oil residing within the receptacle volume towards the drainage conduit. The present disclosure is considered particularly advantageous in connection with gaseous fuels, e.g., hydrogen fuel, where issues related to lubrication oil contamination within the combustion chamber are more prominent as compared to more traditional fuels According to a first aspect of the present disclosure, a piston for a reciprocating internal combustion piston engine is provided. The piston is configured to be arrangeable in a combustion cylinder of the engine, such that a top of the piston faces a combustion chamber, and preferably, the a bottom of the piston faces a crank case. The piston comprises a scraper ring groove for receiving an oil scraper ring. Moreover, the scraper ring groove extends annularly around a circumference of the piston. That is, the scraper ring groove extends around the whole skirt of the piston. In the context of this disclosure, a scraper ring is used to describe a non-compression ring, also known as an oil control ring. That is, the primary function of a scraper ring is to control the amount of lubrication oils passing up and down the cylinder walls and to prevent lubrication oil from entering the combustion chamber, as opposed to that of a compression ring, which is sealing the combustion chamber The piston further comprises a receptacle volume arranged below the scraper ring groove. Such a receptacle volume is suitably delimited by the piston, preferably the body thereof. Preferably, the receptacle volume is of an annular shape, i.e., it extends for a full revolution about an central axis of the piston. Alternatively, the receptacle volume may be provided as one or more discrete, intermittent volumes, suitably also extending about the central axis of the piston. Moreover, such a receptacle volume may be provided internal to the piston, or alternatively, open to an outer surface of the piston. The piston further comprises a receiver conduit extending between the scraper ring groove and the receptacle volume, so as to provide fluid communication therebetween. Suitably, the receiver conduit defines such fluid communication internal to the piston, i.e., within the piston. The piston further comprises a drainage conduit extending from the receptacle volume towards a bottom of the piston. Suitably, the drainage conduit provides fluid communication with the receptacle volume, such fluid communication being preferably internal to the piston. Particularly, a bottom of the receptacle volume has an annular inclination towards the drainage conduit. That is, the bottom of the receptacle volume has different elevations at different circumferential positions of the receptacle volume, such that the drainage conduit is arranged on the bottom of the receptacle volume at an elevation thereo