Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16J—PISTONS; CYLINDERS; SEALINGS
  • F16J9/00—Piston-rings, e.g. non-metallic piston-rings, seats therefor; Ring sealings of similar construction
  • F16J9/12—Details
  • F16J9/14—Joint-closures

Definitions

• the invention relates to an inwardly biassed sealing ring for a piston-ring assembly.
• Piston-ring assemblies operate with a piston ring, which through inherent elasticity presses itself against the cylinder bearing surface of the reciprocating engine. This for instance prevents transfer of fluid in combustion engines from the combustion chamber to the crankcase and passage of oil in the reverse direction. The continual upward and downward sliding movement of the piston ring over the cylinder bearing surface does not cause any considerable wear on the inner jacket however.
• the outward bias of the piston ring is supplemented by the pressure of the fluid which gains access to the space behind the piston ring, that is the space at the inner side of the piston ring.
• the piston ring assembly of the above mentioned specification also comprises a sealing ring that is located at the pressure side of the piston ring and that, unlike the out- wardly biassed piston ring, is biassed inwardly, i.e. it tends to clamp itself down against the inner side of the vertical wall of the piston-ring groove.
• fluid cannot reach the space behind the piston-ring, neither via the mating sides of piston ring and sealing ring, nor via the mating sides of the sealing ring and the bottom of the piston groove.
• the problem remaining is, that the split of the sealing ring has to be made in such a way, that fluid can- not easily flow via the split of the sealing ring to the space behind the piston ring.
• one end of the sealing ring is provided with a narrow protruding part, while the other ring end is provided with a gap correspondingly shaped to accommodate the narrow protruding part with a tight fit, the mating surfaces of said protruding part and the gap extending from the ring surface mating with the inner wall of the piston groove to the ring surface mating with the piston ring.
• the sealing ring with respect to the location of the protruding part and the gap.
• the gap is located in the inner wall of the sealing ring, while in the second embodiment the gap forms a groove in the respective ring end.
• the application of any type of sealing ring in a piston ring assembly for a piston groove of rectangular cross section requires that the mating surfaces of the protruding part and the respective gap are tapered off from the surface mating with the inner wall of the piston groove to the surface mating with the piston ring.
• Fig. 1 is a sectional view of an embodiment of a piston ring assembly comprising a first type of sealing ring.
• Fig. 2 is a three-dimensional view of the above-mentioned embodiment
• Fig. 3A-C are a plan view, a sectional view and a side view of a second embodiment of a sealing ring
• Fig. 4 is a sectional view of an embodiment of a piston ring assembly comprising a third type of sealing ring;
• Fig. 5 is a three-dimensional view of the last-mentioned embodiment of a piston ring assembly
• Fig. 6 are a plan view, a sectional view and a side view of a fourth type of sealing ring.
• Fig. 7-9 are sectional views of three other embodiments of a piston ring assembly.
• Fig. 1 refers to a reciprocating engine, which is shown partly only, and which comprises at least a cylinder 1, in which a piston 2 is accommodated.
• piston 2 is provided with a piston-ring assembly 3 which is accommodated in a groove 4 in the bearing surface around the piston 2.
• a piston with a groove 4 accommodating only one or more outwardly biassed piston rings 5 has the disterio that with the continuous motion of piston 2 the inner wall of cylinder 1 is subjected to heavy wear.
• a wear-affected cylinder causes a pressure loss in the working chamber and hence a loss in engine power (about 5$).
• piston 2 and piston ring assembly 3 has the disadvantage that the space 9 of piston-ring groove 4 above sealing ring 6 will get filled with carbon deposits, so that sealing ring 6 cannot be pressed sufficiently against piston ring 5 by the fluid pressure. This in turn provides again an easy path for the fluid to reach the space behind piston ring 5, causing the wear on the cylinder wall 1 to increase, the risk of fracture of piston ring 5 to become considerable higher, and the problem of obtaining a durable sealing between cylinder 1 and piston 2 to remain.
• Fig. 2 shows a three-dimensional view of the piston ring assembly for a piston machine of Fig. 1.
• This piston ring assembly 3 comprises an inwardly biassed sealing ring 6 and an outwardly biassed piston ring 5.
• the sealing ring 6 is of the split type, where ends 12 and 13 substantially overlap each other; this is achieved by providing the end 13 with a narrow protruding part 14 and the other end 12 with a gap 15 correspondingly shaped to accommodate the narrow protruding part 14 with a tight fit.
• the gap 15 and the protruding part 14 are located in the inner wall of the sealing ring 6 near the piston ring 5.
• the end 12 and the protruding part 14 of the sealing ring 6 comprise mating sides 16 and 17, which closely slide over each other and slope outwardly downwards from the pressure side.
• the cross sectional view of Fig. 1 shows that these mating sides 16 and 17 do not extend diagonally; they start from the inner side 18 and end at side 19 mating with the piston ring 5.
• the end 12 comprises a part, functioning as a damm wall 20 at the inner side 18 of the sealing ring 6, and also a part functioning as a bearing surface of side 19 (for a gastight sealing of the space behind the piston ring 5). This gas-tight sealing is further stimulated by.
• Fluid at the upper side 24 of the sealing ring 6 cannot penetrate the space 8 behind the piston ring 5 via chamber 23 on account of the sealing of the damm wall 20.
• Such an inwardly biassed sealing ring 6, which does not permit a fluid transport to any significant extent to the spice 8 behind the piston ring 5, can appropriately be called a ring 6 with a gas-tight split joint; all other known types of inwardly biassed sealing rings 6 permit a substantial extent of fluid to penetrate the space 8 behind the piston ring 5, so that these rings 6 are in appropriately referred to as gas tight split rings.
• a sealing ring 6 of the type claimed cannot completely prevent the penetration of fluid, the amount of fluid, entering the space 8 behind the piston ring 5, must be carried off via the piston ring 5; this piston ring 5 specially constructed thereto, will now be described.
• the piston ring 5 is provided with two ends 25 and 26 with protruding parts and with adjoining gaps 27 and 28 respectively.
• the ends 25 and 26 comprise mating surfaces 29 and 30, which closely slide over each other and slope outwardly downwards from the pressure side.
• the cross sectionial view of the piston ring assembly in question shows that these mating surfaces 29 and 30 do not extend diagonally; as shown in Fig.
• the contact surfaces 29 and 30 start from the top side 31 of the piston ring 5 and end in the outer wall 32 of this ring.
• the end 25 of the piston ring 5 also comprises a part in the inner wall near the top side of the piston ring 5 and also a part in the outer wall of the piston ring 5; the part in the inner wall also functioning as a damm wall of end 25, is designated by 33. Fluid in the space 8 behind the piston ring 5 will be transported downwards via gap 27 to e.g. the crankcase.
• Fluid in gap 28 cannot reach the space 8 behind the piston ring, neither via the mating surfaces 29 and 30 of the two ends 25 and 26, not via the inner wall of end 25 on account of the damm wall 33 and the further part of the top surface 31 of piston ring 5, on which the sealing ring 6 is pressed to prevent fluid transport to the space 8 behind the piston ring 5 via a passage between the rings 5 and 6.
• a combination of a piston ring and a sealing ring 6 of the type mentioned substantially prevents fluid leakage to the space 8 behind the piston ring 5, and ensures that any fluid penetrated is carried off easily. In this way the fluid pressure in the space 8 behind the piston ring 5 is rather low in comparison with the fluid pressure above the piston 2.
• these surfaces can also be curved (resulting in a concave or a convex surface).
• outwardly biassed gastight piston ring 5 has mating surfaces 29 and 30, which are tapered downwards from the flat top side 31 to the outer wall 32.
• the inwardly biassed sealing ring 6 of the type claimed may only be used in combination with the mentioned piston ring 5 in the given way.
• Y/hen using another type of piston ring 5 (e.g. with a right slot) of the above-mentioned type of piston ring 5 mounted in a reversed position the result wanted will not be obtained; in the first case the piston ring 5 does provide a path for the fluid to the space 8 behind the piston ring 5 and in the second case gap 27 is in connection with the combustion chamber, so that fluid can be supplied to the space 8 behind the piston ring 5, resulting in excessive wear on the piston ring 5 and cylinder 1.
• Fig. 3A shows a plan view of a second embodiment of a sealing ring 6 for a piston ring assembly 3 in a piston groove
• this sealing ring 6 also overlap each other. In this embodiment this is also achieved by providing the end 13 with a narrow protruding part 14 and the other end 12 a gap 15 correspondingly shaped to accommodate the narrow protruding part 14 with a tight fit. In this embodiment , however the gap 1 5 in the end 12 is shaped as a groove; this gap 15 slopes downwards from the inner wall 18 to the surface 19 of the sealing ring 5, which surface mates with the sealing ring 6.
• a cross sectional view of the sealing ring 6 through line AA 1 is shown in Fig. 3B where the protruding part 14 is accommodated in the groove-shaped gap 15, extending from the inner wall 18 to the bottom side 19.
• FIG. 3C Further a side view of this sealing ring 6 is shown in Fig. 3C.
• the application of the above-mentioned embodiments keeps the disadvantage, that the space 8 of the piston groove 4 above the sealing ring 6 and the chamber 11 turned in the upper surface of the sealing ring 6, will get filled with carbon deposits, so that sealing 6 cannot be pressed sufficiently against piston ring 5 by the fluid pressure.
• This in turn provides again an easy path between the sealing ring 6 and the piston ring 5 for the fluid to reach the space 8 behind piston ring 5 with all its consequences.
• a feasible solution to the above problem of carbon deposits is obtained with the use of the type of piston 2 and piston ring assembly as shown in Fig. 4.
• Piston ring assembly 3 for which a piston ring groove 4 is provided in the circumferential surface of the piston, comprises a flat outwardly biassed piston ring 5 and an inwardly biassed sealing ring 6.
• Side 34 of groove 4 situated on the side of the sealing ring 6 is tapered off the outside and the surface of sealing ring 6 mating with side 34 of groove 4 is tapered accordingly.
• sealing ring 6 mating with piston ring 5 is however flat, through the inwardly tapered sides 34 of groove 4 and sealing ring 6 this will result in a force of sealing ring 6 acting in the direction of piston ring Consequently, sealing ring 6 will bear tightly against piston ring 5, and the space 8 behind piston ring 5 will be sealed off from the fluid pressure produced in combustion chamber.
• the inner side of the sealing ring 6 does not bear against the bottom 7 of piston ring groove 4.
• the slope of the taper of groove 4 depends, among others, upon dimensions of sealing ring 6, the coefficient of friction of the applied material, and the magnitude of the fluid pressure.
• the sealing ring 6 in an active piston engine causes the sealing ring 6 to be lifted upwards to excess and so to be pressed outwards against the cylinder wall 1; through the wear acting then between sealing ring 6, outer side 34 and cylinder wall 1, the sealing ring 6 will no longer follow the movement of the piston ring 5 completely, thus permitting the fluid to escape between the sealing ring 6 and the piston ring 5.
• the fluid can therefore penetrate the space 8 behind the piston ring 5.
• the piston groove 4 is provided with a wall part 35 being perpendicular to the direction of motion of the piston 5, where the sealing ring 6 is provided with a correspondingly shaped top surface 36. Therefore, the vibrating action of the piston ring 5 in its groove 4 will hardly move the sealing ring 6 upwards so that the sealing ring 6 will not be pressed against the cylinder wall 1.
• Such a shaped sealing ring 6 is shown in the three dimensional view of Fig. 5, differing from the sealing ring 6 of Fig. 2 in such a way that surface 18 of the sealing ring
• the sealing ring 6 is tapered. In the embodiment of the piston ring assembly 3 shown in Fig. 5 the sealing ring 6 then clamps itself down around the surface 34, thus blocking then the fluid transport via a path between the seeing ring 6 and the bottom 7 of groove 4 to the space 8 behind the piston ring 5.
• FIG. 6A-C A second embodiment of a sealing ring 6 for a piston ring assembly 3 which is accomodated in the piston groove 4 with an .Inner wall 18 tapered off, is shown in Fig. 6A-C; just like the case was in Fig. 3A-C, the end 12 of the sealing ring 8 of this embodiment is also provided with a groove shaped gap 15 while the end 13 is provided with a protruding part 14 correspondingly shaped to accommodate in the gap 15 with a tight fit.
• Fig. 6A-C A second embodiment of a sealing ring 6 for a piston ring assembly 3 which is accomodated in the piston groove 4 with an .Inner wall 18 tapered off, is shown in Fig. 6A-C; just like the case was in Fig. 3A-C, the end 12 of the sealing ring 8 of this embodiment is also provided with a groove shaped gap 15 while the end 13 is provided with a protruding part 14 correspondingly shaped to accommodate in the gap 15 with a
• FIG. 6B shows a cross sectionial view of this sealing ring 6 through line AA 1 , where the side 18 of the sealing ring 6 mating with the tapered inner wall of piston groove 4 is tapered accordingly; further the sealing ring 6 has a flat top 36 which is perpendicular to the direction of motion of the piston 5 to prevent contact between the sealing ring 6 and the cylinder wall 1 through the vibrating action of the piston ring 5.
• the close fitting of the protruded part 14 in the groove shaped gap 15 of end 12 makes tapering of this part (14) and the gap 15 superfluous.
• piston ring 5 can be prevented in two ways to be explained with reference to some embodiments.
• An embodiment of a piston 2 and piston ring assembly 3 according to the invention is shown in Fig. 7, where only a part of side 34 is tapered; the part 37 between the bottom 7 and the side 34 and also that 35 at the outer side of groove 4 are however straight. Since groove 4 near the bottom 7 is rectangular, the flat piston ring 5 is supported in groove 4.
• the sealing ring 6, on the other hand, mates with the sides 34 and 35, and is therefore of a corresponding shape.
• FIG. 8 Still another embodiment of a piston 2 and piston ring assembly 3 according to the invention is illustrated in Fig. 8, where only a part of side 34 situated near the outer side of groove 4 is tapered; the remaining part 37 of side 34 is however straight.
• the groove part 7 with rectangular cross section is of such a with that the combination of piston ring 5 and sealing ring 6 are supported at both sides in groove 4.
• the side of sealing ring 6 mating with the side 37 is of a corresponding shape, causing the sealing ring 6 to be pressed inwards by the fluid pressure produced in the combustion chamber, thereby sealing off the space 8 in groove 4 behind it.
• the piston ring 5 has a restricted movement space as shown in Fig. 9 the special provisions as to the upper surface 36 are superfluous.
• some parts of the sealing ring 6 having sharp edges may be provided with rounded or flattered surfaces 38 to prevent splintering of the edges.
• the inner part 39 of the sealing ring 6 shown in Fig. 8 can be considered as an annular protruding part of the mentioned flat wall 38 shown in Fig. 4.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Pistons, Piston Rings, And Cylinders (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=19833056

Family Applications (1)

Country Status (3)

Cited By (1)

Citations (6)

• 1979
  • 1979-04-25 NL NL7903277A patent/NL7903277A/nl not_active Application Discontinuation
• 1980
  • 1980-04-11 WO PCT/NL1980/000014 patent/WO1980002314A1/en unknown
  • 1980-11-04 EP EP19800900758 patent/EP0027807A1/en not_active Withdrawn

Patent Citations (6)

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