US2604367A

US2604367A - Piston ring

Info

Publication number: US2604367A
Application number: US185802A
Authority: US
Inventors: Samuel H Norton
Original assignee: Thompson Products Inc
Current assignee: Northrop Grumman Space and Mission Systems Corp
Priority date: 1950-09-20
Filing date: 1950-09-20
Publication date: 1952-07-22
Anticipated expiration: 1969-07-22

Description

Jul 22, 1952 s. H. NORTON 2,604,367

PISTON RING Filed Sept. 20, 1950 2 SHEETS-SHEET 1 July 22, 1952 s. H. NORTON 2,604,367

PISTON RING Filed Sept. 20, 1950 2 SHEETSSHEET 2 55a? ZHVEJYLUP Patented July 22, 1952 UNITED STATES PATENT OFFICE 7 PISTON RING Application September 20, 1950, Serial No. 185,802

8 Claims.

This invention relates to resiliently flexible piston rings having circumferentially and axially spaced layers of crown segments joined by inclined cross-overs or webs providing oil cavities therebetween. Specifically, the invention deals with sheet metal oil control piston rings having axially spaced apart scraping edges defined by upper and lower layers of circumferentially spaced crown segments joined through alternate oppositely inclined cross-overs.

According to this invention a flat strip of sheet material such as unhardened spring metal is slit or punched to provide marginal segments along both longitudinal sides thereof. The segments on one side have their mid-points aligned with the ends of the segments on the other side. slits are arranged to define transverse cross-overs or webs connecting the segments. The strip is bent into a channel shape with the segments forming the sides of the channel and the cross-overs or webs forming the web or base of the channel. These webs extend diagonally across the channel to merge into the sides at levels radially outward from the base or foot of the ring. Adjacent cross-overs slope in opposite directions.

In one embodiment of the invention the crossovers or webs lie immediately adjacent each other, being separated only by narrow gaps or slits while in the second embodiment of the invention wide gaps are provided between adjacent cross-overs. In the former embodiment, the increased number of cross-overs reduces the length of the side segments so that the ring will more easily follow uneven contours in a cylinder wall. At the same time less radial pressure will; be exerted on the segments when the ring is circumferentially compressed due to the increased number of cross-overs for absorbing the compression. In the second embodiment, on the other hand, the segments are longer but the wider. gaps provided between the cross-overs afford additional oil drainage capacity.

A feature of the invention resides in the provision of inclined or diagonally sloping webs or cross-overs to produce an increased bracing effect on the axially spaced rings of circumferentially spaced crowns.

Another feature of the invention resides in the provision of alternate oppositely sloping cross-overs each having a side wall component increasing the wall area of the crown segment to which it is attached and each merging with the opposite wall segment radially outward from the base of the ring.

It is then an object of the invention to provide a flexible metal piston ring especially suitable for oil control wherein axially spaced rings of circumferentially spaced crowns are joined by inclined cross-overs or webs imparting increased flexibility to the ring while at the same time reinforcing the crown segments against bending when the ring is compressed or stretched.

Another object of the inventionris to provide a flexible self-expanding groove-defining sheet metal piston ring having axially spaced side walls connected by inclined cross-overs or webs.

A further object of the invention is to provide a sheet metal piston ring having axially spaced rings of circumierentially spaced crown segments wherein each crown segment is connected to an opposite segment by a diagonally sloping web and wherein adjacent webs slope in opposite directions.

A still further object of the invention is to provide a flexible sheet metal type piston ring wherein sloping cross-overs or webs are provided without the use of additional metal.

Other and further objects of the invention will be apparent to those skilled in the art from the following detailed description of the annexed sheets of drawings which, by way of preferred examples only, illustrate two embodiments of the invention.

On the drawings: 7

Figure l is plan view of one form of piston ring according to this invention.

Figure 2 is a fragmentary plan view of a strip of metal cut or punched to produce a blank for the ring of Figure 1. I

Figure 3 is a fragmentary isometric view of a channel strip formed from the blank of Figure 2.

Figure 4 is a fragmentary edge view of the strip of Figure 3.

Figure 5 is a transverse crosssectional view taken along the line V--V of Figure 4.

Figure 6 is a somewhat diagrammatic view illustrating a rolling operation for tapering the crown segments of the strip of Figure 3 to produce wedge-shaped or keystone shaped segments.

Figure '7 is a fragmentary plan view of a rolled strip from the rolling operation of Figure 6 partially coiled into a piston ring shape.

Figure 8 is a cross-sectional view of a piston ring and cylinder assembly having a piston ring of this invention in the oil groove of the piston.

Figure 9 is a plan view of a modified piston ring according to this invention.

Figure 10 is a fragmentary plan view of a punched or cut strip of metal for producing the ring of Figure 9.

other longitudinal edge into spaced relation with the first mentioned longitudinal edge. The ends of the cuts I2 and I3 are spaced inwardly from the longitudinal edges of the strip the same predetermined amount to control the radial depth isegments I 4 and I 5 lyingv outwardly from, the

.. ends..o,f the .-cu s s'sh wnh e me t 14 lying between thfilcuts g I 2 have .their mid-points .transve sely..aligned with gthe ends r the. segmentsl5 lying betWeenthe cuts I3. 'These seg- Iments I Land I5 arejoined through parallel adjacent webs or cross-overs I6.

The. cut blank of Figure 2 isbent intoa channel' stripe shape shown at H in Figure 3. This channel strip I'I hasoneside wall composed of the segments I4 ,separate d by the slits I2 and an opposite side wall, composed of'the segments I5 separated by theslits I3. The sidewalls are joined .bythecrosswversor webs I6.

.Each cross-over has. a leg portion I 6d lying, in

.the, sameplane as the adjacentsegment, I4 or I5 .a n d extending to a rounded footportion. Ifib spaced radially inward from the segments. ,The foot portion. merges into a diagonally sloping portio 150 .which; extends. axially. across the, channel of. the strip and, radially. outward to. merge into the opposite segment at a, rounded-knee portion 15d which is much closentdtheouter open face of the channel than the foot Ifib.

.- Adjacent, cross-overs. I 3 slope .in opposite directionsso. that each segment I4. and .I5.will have an extended wall. portion formed. bya. leg

Ilia. and an adjacent gap I8 under the diagonally sloping leg portion I60 of an adjoining crossover.

Since coiling of the strip I'I- into ring shape will open upthecuts I2 and I3 between the segments Hand I5 into V-shaped gaps of uncontrolled dimensions, the segments I I- and I5 are tapered by a pressing operation shown in Figure 6-.which flows the metal-of the segments laterally outward to convert the segmentsintowedge or keystone shape. As shown in Figure 6, the-strip I1 is disposed over a mandrel roll I9.having a tapered periphery projecting into the channel of the ring into seated engagement with the inner faces-of thesegments I4. and I5. The outer faces of these segments vare pressed by. rolls. 20 v and .2l respectivelyand thev segmentsare tapered toward-theirouter edgesto provide thinned down active edges 22 and- 23. respectively.

As shown in Figure 7, the segment tapering operation. flows. the metal of. the segments. laterally ,to'provide. wedge shaped or keystoneshaped segments having V-shaped grooves or gaps 24 therebetween which form into radial gaps I3 when the strip is coiled into a ring. Thesegaps conform with the original slits between the-segments and can, be of, controlled width.

The coiled strip is subjected to ahardening and drawing treatment to develop the spring like properties of the metal and the resulting ring I!) is circumferentially compressible so as to have self-expanding action when mounted in a piston and cylinder assembly shown in Figure 8. As therein shown, the ring I0 is seated in the oil groove 25 of a piston 26 and acts on the wall of a cylinder 21 in which the piston operates. An oil drain hole 28 is provided for the groove 25. The

edges

22 and 23 of the piston ring act on the wall 21 and confine a space 29 in the channel of the ring which is drained through the gaps I8 into the drain holes such as 28 thereby control- .ling the metering of oil along the cylinder Wall.

The. scrapingedges 22 and 23 are ground to circularshapeand the feet I6 firmly bottom the ring on a supporting mandrel during the grindingoperation to insure a formation of accurately ground edges.

Since the cross-overs I6 lie adjacent each other, the ring segments I4 and I5 are relatively short and are not easily deflected. In addition. the legs Ilia of the cross-overs afford added seating area forthe sides of the ring to add to the rigidity of the segments. The inclined or diagonal portions of the cross-overs absorb compression stresses without building up appreciable wall pressure between the edges 22v and 23 and the cylinder wall. Since the segments I4 and I5 are quite short, the ring can easily follow irregularities in the contour of the cylinder wall.

In the second embodiment of the. invention, shown in Figures 9 to 13, the. piston ring .3ll. of FigureQ is formed from a punched fiat metal strip 3i of Figure 10. The strip3l has rectangular slugs punched out of the central portion thereof in, spaced parallel relation to provide spaces 32 alternating with cross-oversor webs 33. Slits 35 extend transversely inward from one longitudinal edge of the strip 3I in alignment with one edge of the adjacent opening 32. slits 35 extend transversely inward from theother longitudinal edge ofrthe strip in alignment with one edge of. the

openings 32 lying between those openings havim;

' the strip. The segments 36 lie between the slits 34 and the mid-points of these segments are aligned transversely with the ends of the segments 3! lying between the slits 35. Each

segment

36 and 31 has a pair of integral cross-overs or webs extending therefrom with one web lying adjacent one end of the segment and the other web being intermediate the ends of the segment.

The blank SI of Figure 10 is bent into the shape of a channel to form the strip 38 of Figure 11 with the segments 36 and 3? forming the sides of the channel and the cross-overs 33forming the base or web of the channel. The punched out spaces 32 provide gaps between the webs or cross-overs 33.

Each cross-over 33 has a leg portion 33a lying in the same plane as the

adjacent segment

36 and 31 and extending in this plane to a rounded foot portion 33b spaced inwardly or beneath the segments. The rounded foot portion merges into an inclined cross leg 330 which spans the channel of the strip and merges into a rounded knee 3311 at the opposite segment. The knee 33d is radially outward or upward from the foot 33b.

Adjacent cross-overs 33, separated by the gaps 32, are oppositely inclined so that the leg portions 33a of adjacent cross-overs will be on opposite sides of the channel and each segment will be equipped with an extended leg portion.

Wide gaps or oil cavities 39 are provided between the legs 33a on each side of the ring under the inclined legs 330 of the cross-overs in merging continuity with the gaps 32 provided by the punched out portions.

The

segments

36 and 37 are tapered or keystoned in the same manenr described in connection with Figure 6 to provide the finished ring 35! with gaps between the segments of uniform width.

The ring 3!) functions like the ring I!) and has the inclined cross-overs bracing the sides against bending. Since less cross-overs are provided, they must be deformed to a greater degree to accommodate circumferential compression and the ring 39 will exert more wall pressure on a cylinder wall than the ring Ill. However, the larger gaps provided by the ring 30 will accommodate better drainage of oil than the smaller gaps in the ring [0.

If desired, the

slits

34 and 35 in the blank 3! could be displaced so as to extend into the centers of the punched out portions 32 thereby providing more symmetrical segments. In either event, the slits in opposite segments will be oifset from each other to control the metering of oil.

From the above descriptions it will therefore be understood that the invention provides flexible self-expending piston rings with inclined web portions or cross-overs connecting the segments of axially spaced rings or side walls. The inclined cross-overs afford additional wall area for the segments, While at the same time providing a di agonal bracing to protect the segments against bending.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. A resilient self-expanding piston ring having an open-faced channel with side walls composed of circumferentially spaced ring segments and a back wall composed of circumferentially separated inclined webs integrally connected to said side walls and being resiliently deformable to accommodate compression and expansion of the ring.

2. A piston ring comprising a strip of resilient sheet material formed into an annular channel and having side walls composed of circumferentially spaced segments together with a base wall composed of inclined webs with adjoining webs being inclined in opposite directions and having gaps therebetween connecting the interior of the channel with the outside of the ring.

3. A sheet metal flexible self-expanding piston ring comprising axially spaced ring layers connected by circumferentially spaced cross webs, each web having a leg portion lying in the same plane as the adjacent layer and extending the area of said layer together with an inclined pertion extending between the layers and connected with the opposite layer radially outward from. the end of the leg portion.

4. A self-expanding resilient flexible piston ring comprising axially spaced ring layers and circumferentially spaced cross webs connecting said ring layers, adjacent cross webs having oppositely inclined portions spanning the space between the rings and providing gaps there between.

5. A piston ring comprising spaced apart sides composed of a plurality of ring segments, each of said segments being supported by an integral web, and adjacent webs being oppositely inclined between the sides.

6. A piston ring comprising a channel-defining ring having sides with peripheral edges adapted to engage a cylinder wall and flat faces adapted to seat i a piston ring groove, cross webs connecting said sides, each of said webs having a leg portion extending the face area of a side and an inclined portion extending between the sides into merging relation with the opposite side i a plane radially outward from the inner end of the leg portion.

7. A piston ring comprising axially spaced flat rings each composed of circumferentially spaced ring segments, inclined cross webs connecting said rings and being integral with said ring segments, said inclined cross webs accommodating circumferential compression of the ring without bending the ring segments and each segment having a pair of oppositely inclined webs in closely spaced adjacent relation.

8. A piston ring comprising a channel defining annulus having sides composed of circumferentially spaced ring segments, each ring segment having an open slot at its inner periphery and a pair of integral cross webs sloping in opposite directions across the channel.

SAMUEL H. NORTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,267,367 Bowers Dec. 23, 1941 2,277,307 Crawford Mar. 24, 1942 2,380,421 Engelhardt July 31, 1945 2,399,683 Loeb May 7, 1946