GB2108237A

GB2108237A - Internal combustion engine having a split piston ring

Info

Publication number: GB2108237A
Application number: GB08228820A
Authority: GB
Inventors: Ludek Bazil
Original assignee: Sulzer AG; Gebrueder Sulzer AG
Current assignee: Sulzer AG
Priority date: 1981-10-23
Filing date: 1982-10-08
Publication date: 1983-05-11
Also published as: SU1240367A3; IT8223531A0; IT1152844B; JPS5877142A; DE3143306A1; JPS6236148B2; DE3143306C2; GB2108237B

Abstract

An internal combustion engine has a split piston ring (28,30) formed in its operative surface (34) with a peripherally extending groove (36,50). The operative surface (16) of the cylinder is formed with lubricating grooves (18) which extend at an inclination to the peripheral direction. The piston-ring groove (36,50) communicates by way of at least one duct (40,52) extending at an inclination to the peripheral direction, with that side of the piston ring (28,30) which is near the cylinder head. <IMAGE>

Description

SPECIFICATION Internal combustion engine having a split piston ring This invention relates to an internal combustion engine having a split piston ring formed in its operative surface wth a peripheral groove, the operative surface of the engine cylinder being formed with lubricating grooves at an inclination to the peripheral direction.

Reciprocating internal combustion engines having piston rings and cylinder operative surfaces of the kind outlined have already been proposed; for instance, in the case of so-called gastight piston rings the main function of the peripheral groove is to provide relief from the gas pressure in order to reduce cylinder wear. Grooves of this kind are also used in ordinary open-latch piston rings in order to improve lubrication by providing a kind of oil storage effect.

Unfortunately, these constructions have the disadvantage that peripheral oil distribution along the groove is unsatisfactory. Also, such peripheral grooves readily become clogged by material abraded from the cylinder and by combustion residues, with the result, more particularly in the case of heavy oil engines, that the betweenservicings time is relativeiy short. United States Patent Specifications 1 401 930 and 1 710 485 disclose piston rings formed with grooves extending at an inclination to the peripheral direction. However, there is no peripherally extending groove.

It is an object of the invention to provide an internal combustion engine which has considerably improved peripheral oil distribution and, therefore, improved running properties. According to the present invention, an internal combustion engine has a split piston ring formed in its operative surface with a peripheral groove, the operative surface of the engine cylinder being formed with lubricating grooves at an inclination to the peripheral direction, the groove in the piston ring communicating, by way of at least one duct disposed at an inclination to the peripheral direction, with that side of the piston ring which is near the cylinder head. With this arrangement, when the piston ring passes over the lubricating grooves, the gas pressure produces a peripheral oil flow in the groove in the piston ring.As a result, not only is satisfactory peripheral oil distribution achieved but also there is effective scavenging of the piston-ring groove in order to remove abraded material and combustion residues. Also, the duct, in co-operation with the piston-ring groove, serves for pressure equalisation instead of the conventional bores.

Very advantageously, the duct can have substantially the same direction of inclination as the lubricating grooves in the operative surface of the cylinder.

This leads to a considerable acceleration in the flow of oil in the lubricating grooves, through the agency of the gas pressure which is operative in the flow direction.

Preferably, the cylinder lubricating grooves can extend at substantially the same inclination as one another. This helps to produce an additional whirling effect which increases considerably the peripheral flow velocity of the oil.

Also, the groove in the piston ring can terminate at each end short of the piston ring latch, so that the sealing effect thereof is not impaired. Preferably, then, at least one duct leads from a point in the piston ring groove which is adjacent one end of the piston ring groove. This obviates a dead corner and ensures that the groove is scaveneged right up to the end.

The invention may be carried into practice in various ways but one engine embodying the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure lisa longitudinal section through the cylinder of the engine, and a piston with piston rings in the cylinder; Figure2 is a view to an enlarged scale showing a part of one of the piston rings of Figure 1, the view being in the plane of the ring; Figure 3 is a plan view corresponding to Figure 2; Figure4 is a view similarto Figure 2 of part of another of the piston rings of Figure 1,this ring being a gas-tight piston ring; and Figure 5 is a section on the line V-V of Figure 4.

A cylinder liner 10 (Figure 1) of a two-stroke large diesel engine, for instance a marine diesel engine, has inlet ports 12 and exhaust ports 14 and is formed on its inner cylinder wall 16 with inclined lubricating grooves 18; these grooves have substantially the same direction of inclination as one another and are supplied with lubricating oil by way of lubricant bores 20. A piston 22 which reciprocates in the liner 10 has a top part 24 in which conventional piston rings 26 are guided in piston-ring grooves and piston rings 28,30 to be described are guided in peripheral grooves. The piston top part 24 merges into a bottom part 32 having a substantially cylindrical outer surface of smaller outer diameter than the outer diameter of the top part 24. The piston 22 is secured to a piston rod (not shown) whose other end is pivotally connected to a crosshead (not shown).

Referring to Figures 2 and 3, the piston ring 28 has an operative or running surface 34 adapted to be engaged with the operative or running surface of the cylinder wall 16 or the liner 10. The ring 28 is formed on its outside with a peripheral groove 36 and has a latch in the form of a gap 38 which provides resilience and enables the surface 34 to be pressed onto the cylinder wall 16.

The ring 28 has ducts 40 which extend at an inclination to the peripheral direction, terminate in the groove 36 and are disposed relative to the plane 42 of the ring at an angle a of, conveniently, more than approximately 30 but less than 90 . The direction of inclination of the ducts 40 is approximately the same as the direction of inclination of the lubricating grooves 18 in the operative surface of the cylinder.

Figures 4 and 5 show the gastight piston ring 30 which has as its latch 44 parts 46,48 which engage with one another at the ring ends, in the manner known, for instance, from Swiss Patent Specification 482 954. In this case the peripheral groove 50 terminates at each end short of the latch 44, ducts 52 extending into the groove adjacent its end.

As an example of how the engine operates, it will be assumed that the gas pressure is moving the piston 22 from its top dead centre position towards the crankshaft, the diagrammatically shown lubricating groove 18 coinciding with the peripheral groove 50 in the manner visible in Figure 4. Gas flows through the duct 52 and groove 50 in the direction indicated by an arrow 54, part of the gas flow moving in the direction indicated by an arrow 56 through the groove 18 and accelerating the flow of lubricating oil therethrough. Another part of the gas flow scavenges the peripheral groove in the direction indicated by an arrow 58. Also, the ducts 40, 52 communicating with the groove 36, 50 serve for pressure equalisation.

As will be apparent from Figures 1 and 4, the fact that there are ducts 52 adjacent the ends of the peripheral groove 50 obviates any deposition of residues in dead corners at the groove ends 60, 62.

Ducts 40, 52 can of course be embodied at least to some extent as bores.

Claims

1.An internal combustion engine having a split piston ring formed in its operative surface with a peripheral groove, the operative surface of the engine cylinder being formed with lubricating grooves, the groove in the piston ring communicating, by way of at least one duct with the side of the piston ring which is near the cylinder head.

2. An engine as claimed in Claim 1 in which the lubricating grooves each extend at an inclination to the peripheral direction.

3. An engine as claimed in Claim 1 or Claim 2 in which the or each duct is disposed at an inclination to the peripheral direction.

4. An engine as claimed in Claim 2 in which the lubricating grooves extend at substantially the same inclination as one another and the or each duct has substantially the same direction or inclination as the lubricating grooves.

5. An engine as claimed in any of the preceding claims in which the groove in the piston ring terminates at each end short of the piston ring latch.

6. An engine as claimed in Claim 5 in which the duct or one of the ducts leads from a point in the piston ring groove which is adjacent one of the ends of the piston ring groove.

7. An internal combustion engine having a split piston ring formed in its operative surface with a peripheral groove, the operative surface of the engine cylinder being formed with lubricating grooves at an inclination to the peripheral direction, the groove in the piston ring communicating, by way of at least one duct disposed at an inclination to the peripheral direction, with that side of the piston ring which is near the cylinder head.

8. An engine as claimed in Claim 7 in which the cylinder lubricating grooves extend at substantially the same inclination as one another.

9. An engine as claimed in Claim 8 in which the or each duct has substantially the same direction or inclination as the lubricating grooves in the operative surface of the cylinder.

10. An engine as claimed in Claim 7 or Claim 8 or Claim 9 in which the groove in the piston ring terminates at each end short of the piston ring latch.

11. An engine as claimed in Claim 10 in which the duct or one of the ducts leads from a point in the piston ring groove which is adjacent one of the ends of the piston ring groove.

12. An internal combustion engine substantially as described herein with reference to the accompanying drawings.