CA1057327A - Piston oil control ring - Google Patents

Abstract

PISTON OIL CONTROL RING

Abstract In a composite oil control ring for recipro-cating piston internal combustion engines, of the type which includes a relatively soft parted cast iron ring and an expander-spring disposed internally of the ring to bias the same into sealing engagement with a cylin-der wall, a parted annular insert rail of wear-resistant metal is disposed between the expander and the ring to reduce wear on the ring and to prevent embedment or unitization of the ring and spring.

Description

The present invention relates to piston rings and, more specifically, to a composite oil control ring of the type which includes a parted cast iron sealing ring and a separate ring-expanding spring.
In prior art oil control rings of the type described, using a parted, relatively soft cast iron ;
sealing ring and a harder metallic expander-spring, .
high unit loading between the ring and spring about the inside ring diameter causes excessive wear to both parts. This wear often leads to embedment of the spring into the ring which unitizes the two parts, ; causing loss of oil control and ultimate engine fail-; ure.
It is an object of the present invention to ., provide a composite oil control ring of the described ~ type which is both economical in assembly and reliable ; in operation; and which, more specifically, eliminates the above-mentioned problem of excessive wear on the sealing ring and consequent unitization of the ring ''.' and expander-spring.

The novel features which are considered to be characteristic of the present invention are set -~ forth in particular in the appended claims. The in-vention itself, however, together with additional .,.~ , i'. ~
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~0573Z7 objects, features and advantages thereof, will be best understood from the following description when read in conjunction with the accompanying drawings in which:
FIG. l is a fragmentary view of a cylinder and a piston equipped with one embodiment of the com-posite oil control ring in accordance with the inven-tion, a portion of the piston and ring being broken away to illustrate ring assembly;
` FIG. 2 is a plan view, partially broken, . 10 showing the composite oil control ring of FIG. l;
FIG. 3 is an exploded perspective view, par-tially broken, showing the separate components of the composite control ring of the invention;
FIG. 4 is a view in radial cross section of the composite ring according to the invention and is ; taken along the line 4-4 of FIG. 2;
FIGS. 5-10 are elevated views of various in-.:. sert rail embodiments useful in the composite rings ; shown in FIGS. 1-3 and 4; and ` 20 FIGS. 11-13 are plan views, partially broken, showing other embodiments of composite rings in which the present invention may be used.
Referring to FIG. l, there is shown a con-~ ventional piston 20 disposed to reciprocate within : a cylinder 22 of a gasoline- or diesel-powered inter-~ nal combustion engine. Piston 20 is provided with the ~ .,, : ~ usual peripheral groove in which is disposed a com-:`
.. --2--10573;Z7 posite oil control ring 24 in accordance with the in-vention.
Referring to FIGS. 2-5 which show in greater detail composite oil control ring 24, the composite ring comprises a conventional parted cast iron sealing ring 26 and a split annular coiled expander-spring 28 disposed internally of ring 26 within the associated piston groove, spring 28 being disposed in an opposing, - -~
radially inwardly facing spring-receiving groove or channel 30 in ring 26. Spring 28 is circumferentially expanding, whereby ring 26 is expanded by spring 28 in the circumferential direction into sealing engage-ment with the opposing wall of cylinder 22 (FIG. 1).
, A composite oil ring of the type so far discussed is shown and discussed in greater detail in the Hesling patent 3,195,903.

In general, ring 26 is cast of relatively `

~ soft iron and may have a hardness on the order of ~- Rockwell (B) 95-106. By contrast, spring 28 is usual-ly relatively hard and may be made of 302 stainless ; spring steel which has a hardness on the order of :
. Rockwell (C) 40. Hence, during operation of piston 20 :~ (FIG. 1), interaction between the inner ring diameter - and the opposing outer spring diameter causes the ring , ., ~573Z7 to wear, and may allow the convolutions of the coil spring to become embedded in the opposing ring sur-; face. This embedment unitizes the ring and spring such that the ring can no longer freely expand and contract, and can no longer follow the opposingcylinder wall.
In accordance with the present invention, to prevent such ring wear and ring/spring unitization a parted or split annular insert rail 32 of coiled wear-resistant ribbon material, such as 1095 steel, ; for example, having a hardness on the order of Rock-well (C) 50-56, is disposed in ring groove 30 between spring 28 and ring 26. Insert rail 32 has opposite ,s radial faces 32a,32b engaged by spring 28 and engaging - 15 ring 26 respectively. Using the materials described, ;
, insert 32 is harder and more wear-resistant than both :.
` ring 26 and spring 28, such that interaction between the insert and spring along their opposing surfaces tends to cause wear on the spring rather than on the insert or ring whereby the problem of unitization and oil control failure are relieved. It is also within ; ~., .
- the scope of the invention to provide an insert 32 which .:.
is softer and less wear-resistant than is spring 28 whereby the insert tends to wear rather than the ~ 25 spring. The primary consideration is that, if wear ,. j .

1C~573Z7 and/or unitization is to take place in the composite ring according to the invention, the sealing ring 26 is not worn and the sealing ring never becomes unit-ized, either directly or indirectly (i.e., via insert r, 32), with expander-spring 28.

Insert 32 may be affixed or attached to ring 26 within groove 30. Such attachment may be accom-plished by press fitting insert 32 into groove 30, by providing suitable burrs on the axial edges of the insert, or by welding or other forms of adhesion. When the ring 26 and insert 32 are attached, the gaps thereof must be aligned, as shown at 33 of FIG. 2, so that the ring/insert combination can expand circumfer-entially into sealing engagement with the cylinder wall.
Of course, where the ring and insert are attached, the -, insert must be more wear-resistant than the spring so that the spring will not become unitized with the ring/insert combination. where it is desirable to use an insert which is less wear-resistant than the spring, the insert should be "free floating" within ring groove 30, in which case, of course, it is not , necessary to align the ring and insert gaps.
Although the present invention has hereto-fore been described in conjunction with a coil-type .~ .

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expander-spring 28, it will be apparent that the in-vention is equally useful with other types of expander-springs, such as a hump- or wavy-type spring shown at 34 in FIG~ with a conventional zig-zag spring of 5 the type shown at 48 in FIG~ 12 and disclosed in Baker 2,891,831, or with an expander of channel-shaped cross section of the type shown at 50 in FIG~ 13 and disclosed in Mayhew et al 3,281,156. More generally, the present invention is useful in combination with 10 any of the well-known types of split oil control ring/
circumferentially expanding spring combinations.
Insert rail 32 may be either solid, as shown in FIGS~ 3 and 5; may be provided with a circumferential array of centrally-disposed oil vents, as shown at 38 15 in FIGo 6 or 40 in FIG~ 7; or may be provided with staggered circumferential arrays of side or edge vents along the respective rail edges, as shown at 42 in FIG~ 8, 44 in FIG~ 9 or 46 in FIG~ 10~
The insert rail may be either coiled or 20 flat in its free state, the insert assuming the form of a parted annulus in assembly of the composite ring.
Similarly, the inside, spring-engaging face of the insert nlay be flat, as shown in the drawings, or may be contoured to more closely conform to the opposing 25 portion of the expander-spring The invention claimed is:

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1.
A composite oil control ring adapted for use as a seal between the piston and cylinder wall of a reciprocating piston internal combustion engine wherein the piston is provided with a piston groove, comprising a parted sealing ring adapted to be disposed in said piston groove for sealing engagement with said cylinder wall and having a radially inwardly facing ring groove opposite the sealing edge thereof, an annular self-expanding spring disposed internally of said ring groove and adapted to be spaced from the base of said piston groove and circumferentially to expand said ring into sealing engagement with said cylinder wall, and a parted annular wear-resistant insert disposed between said sealing ring and said spring in said ring groove and having opposite radial faces engaged by said spring and said ring respectively, whereby the expanding force of the spring is transmitted through said insert to said ring.

2.

The composite oil control ring set forth in claim 1 wherein said insert comprises a parted annular rail coiled of wear resistant or wear-coated metal ribbon stock.

3.
The composite oil control ring set forth in claim 2 wherein said insert is attached to said ring internally of said groove in said ring.

4.

The composite oil control ring set forth in claim 3 wherein the gap in said parted ring is radially aligned with the gap in said parted insert.

5.

The composite oil control ring set forth in claim 1 or 2 wherein said insert is free floating in the groove in said ring.

6.

The composite oil control ring set forth in claim 1 or 2 wherein said insert includes a plurality of circumferentially disposed oil vents extending radially therethrough.

7.

The composite oil control ring set forth in claim 1 or 2 wherein said insert is fabricated of a metal which is harder than either said ring or said spring.