US2621989A

US2621989A - Piston ring

Info

Publication number: US2621989A
Application number: US185801A
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: 1952-12-16
Anticipated expiration: 1969-12-16

Description

Dec, 16, 1952 s. H. NORTON 2,621,989

PIsToN RING Filed Sept. 20, 1950 2 SHEETS-SHEET 1 ITJ'JJ @.2 5 J6 2 z i Dec. 16, 1952-'- s. H. NORTON 2,521,989

PISTON RING Filed Sept. 20, 1950 2 SI-IEETS--Sl-IEET 2 22 f5 j??? 46249 fg; /Wl

Patented Dec. 16, 1952 PISTON RING Samuel H. Norton, University Heights, Ohio, as-

signor to Thompson Products, Inc., Cleveland, Ohio, a corporation of Ohio Application September 20, 1950, Serial No. 185,801

3 Claims. 1

This invention relates to exible sheet metal piston rings having strut-reinforced rows of crown segments joined by webs and providing peripheral oil scraping edges.

Specifically the invention relates to flexible oil metering or control rings for pistons wherein a circumferentially expansible resilient channeldefining ring has reinforcing struts between webs connecting the sides of the ring and extending alternately from opposite sides across the channel to abut the opposed sides.

According to this invention, dat strip stock such as unhardened spring steel is cut or punched to provide marginal crown-defining segments along the outer edges thereof joined by cross webs which are separated from each other by strut-dening tabs. In one embodiment of the invention, the cut or punched strip has no slugs removed therefrom. In another embodiment of the invention, small slugs are punched out of the strip at the ends cf the strut-forming tabs so that these struts can extend straight across the channel of the nished ring. The punched strip is bent to form side walls of crown segments joined by the web portions. The strutforming tabs lying between the web portions are bent to extend across the channel between the crown segments from the segments to which they are attached to the opposed segments so that the free ends thereof thrust against the opposed segments. The tabs are so cut that adjacent struts extend alternately from opposite crowns. In the embodiment of the invention wherein no slugs are punched from the strip, the struts are bent along a curved path extending from the crowns to which they are attached between the webs and thence diagonally into the channel to a level intermediate the ends of the opposing segments and thence axially across the remaining portion of the channel into thrusting engagement with the segments. In the form wherein slugs are cut from the strip, the struts are bent at substantially right angles to the crowns to which they are attached and thence axially across the channel into abutting engagement with the opposed crown. The struts in both embodiments are arranged so that the free edges thereof will span two adjacent crown segments.

The crown-carried struts ci this invention are 'f The struts being fastened i crowns, add support to the crowns and keep them from bowing or concaving when the piston ring is stretched or compressed. At the same time, the flexibility of the ring is not impeded and the ends of the crown are lined up against the ends o f the struts to prevent saw-toothing of the sides of the ring.

Piston rings are formed from the channeled blanks of this invention by the conventional forging of the blank into circle shape by coining or rolling the crown segments into wedge shape and by hardening and tempering the metal to provide a spring.

The exible rings of this` invention are circumferentially expansible toY provide sealing pressure against the cylinder bore at all points even when material variations in the bore contour develop through wear.

It is, then, an object of this invention to provide a exible sheet metal piston ring having reinforcing struts formed integrally with the sides of the ring.

Another object of the invention is to provide a flexible sheet metal piston ring of the channeldefining type having crown segments providing scraping edges and spaced webs connecting said segments together with reinforcing struts between said webs bridging the channel and thrustincr against the crown segments.

A specific object of the invention is to provide a iiexible sheet metal piston ring having axially spaced scraping edges formed from a plurality of segments connected by circumferentially spaced webs and rigidied by reinforcing struts between the web that extend alternately from opposite segments into thrusting engagement with the end portions of two opposed segments.

Another specific object of the invention is to provide a channel-type piston ring with reinforcing struts bridging the channel with adjacent struts extending integrally from opposite sides of the channel.

A still further object of the invention is to provide a sheet metal pistonk ring of the type having axially spaced segments connected vby circumferentially spaced webs with reinforcing struts between the webs which are integral with opposed alternate segments to rigidify the segments against bowing or concaving when the ring is stretched or compressed. Y v

Another object of the invention is to provide a strut-reinforced channel-type sheetmetalnpiston ring made from the same amount of blank metal as channel-type rings not equipped with reinforcing struts.

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.

As shown on the drawings:

Figure 1 is a plan view of one embodiment of piston ring according to this invention.

Figure 2 is a fragmentary plan view of a punched or cut metal strip providing a blank for forming the ring of Figure 1.

Figure 3 is a fragmentary isometric view of a channel strip formed from the blank of Figure 2 in the production of the ring of Figure 1.

Figure 4 is a transverse cross-sectional view of the strip of Figure 3.

Figure 5 is a diagrammatic view illustrating the step of rolling the sides of the channel strip into tapered wedge shaped segments.

Figure 6 is a fragmentary plan view of the rolled strip.

Figure 7 is a fragmentary plan view of the rolled strip of Figure 6 after it is forced into the Circular shape of the nished piston ring.

Figure 8 is a fragmentary vertical cross-sectional view taken through a piston and cylinder assembly illustrating the piston ring of this invention mounted in the oil ring groove of the piston.

Figure 9 is a plan view of another embodiment of piston according to this invention.

Figure 10 is a fragmentary plan view of a punched strip providing a blank for forming the modified piston ring of Figure 9.

Figure l1 is a fragmentary isometric view of a channel strip formed from the blank of Figure 10 in the production of the ring of Figure 9.

Figure 12 is a transverse cross-sectional View of the channel strip of Figure 1l.

Figure 13 is a fragmentary cross-sectional view of a piston and cylinder assembly including the piston ring of Figure 9 in the oil ring groove of the piston.

As shown on the drawings:

The piston ring Ill of Figure 1 is formed from a flat strip of unhardened spring metal stock by cutting or punching transverse slits I2 inwardly from the opposite edges of the strip. The slits I2 alternate on opposite sides of the strip so that the slits on one side are midway between the slits on the other side. Each slit I2 extends inwardly from the edge of the strip to a longitudinally extending cut or slit I3. The slits I 3 are intersected by the slits I2 at their mid-points and extend longitudinally to transverse elongated slits I4 in spaced parallel relation. The slits I4 terminate flush with the adjoining slits I3 on the opposite marginal portion of the strip. The blank I I therefore has a row of longitudinally extending segments I5 along one marginal edge thereof and a similar row I6 along the other marginal edge thereof. The segments I5 and I6, however, are staggered transversely with the mid-points of the segments on one side aligned with the ends of the segments on the other side. The segments I 5 and I6 are connected through spaced parallel transverse Webs I'I lying between tabs I8 having three free sides and a connected end at the mid-points of the longitudinal segments I5 and I6. One tab is connected t0 a segment I5 while the adjacent tab is connected to the opposed segment I 6.

As shown in Figure 3, the blank I I is bent into a channel-shaped strip I9 having opposed sides formed by the segments I5 and I6 and connected by the webs II. These webs are bent along the 4 dotted line X-X of the blank I I so that the end portions of the webs lie in the same planes as the segments while the central portions of the webs are at right angles to the segments.

The tabs I8 lying between the webs I'I are bent in spaced relation from their connected ends and thence into the channel of the strip to bridge the channel and have their free ends abut the opposite segments in spanning relation to the cuts or slits I2 between the segments.

Therefore, as shown in Figure 3, each web I7 will have a leg portion I'Ia in the same plane as the sides of the channel dened by the segments I5 and I6 and will have a central leg portion or connecting web IIb at one end of the channel in right angular relation to the sides. The tabs I8, when deflected to form the struts. will have rounded leg portions I8a extending from the ends thereof connected with the segments into flush relation with the cross legs I'Ib of the webs and somewhat inwardly from the end leg portions I 'Ia of the webs. The curved portions I8a of the tabs extend to diagonal middle portions Ib in the channel and these diagonal portions terminate in end legs I8c at right angles to the side segments I5 and I6. These free ends I8c are positioned inwardly from the outer edges of the segments I5 and I6 and outwardly from the inner edges of these segments.

The channel strip I9 of Figures 3 and 4 is rolled as shown in Figure 5 to taper the segments I5 and I6 for forming them into Wedge shape. As shown in Figure 5, the strip I9 receives the tapered periphery of a mandrel wheel 20 in the outer end of the channel to a depth limited by the tabs I3 in the channel. Pressure rolls 2I act on the outer sides of the strip and coact with the mandrel for working the segments I5 and I6 into a tapered configuration which flows metal laterally and produces wedge-shaped crowns tapering to

thin edges

22 and 23 respectively. As shown in Figure 6, the tapered segments I6 will have V-shaped spaces 24 therebetween, since the segments will be keystone or Wedge shaped with their widest ends at the edges.

As shown in Figure 7, the strip is coiled into circular form to produce the shape of the finished piston ring I0. This nished piston ring has radial gaps 25 of substantially uniform width between the tapered crowns I5 and I6 and has open spaces 26 at the inner ends of the gaps between the webs. The crowns I5 and I6 are integrally connected between the webs with the reinforcing struts and are thereby rigidied against bowing or concaving when the ring is stretched or compressed. The free ends of the struts abut the ends of the crowns on each side of the gaps 25 and thereby line up adjacent crowns to minimize saw-tooth effect along the sides of the ring.

After coiling the strip into ring shape as shown in Figure 7, the finished ring is hardened and tempered to produce the desired spring properties therein and, as shown in Figure 8, the ring I0 fits in the oil groove 21 of a piston 28 to act on the cylinder Wall 29 with its scraping edges 22 and 23 while accommodating drainage of oil from the conned channel 30 to oil drain holes such as 3| through the open spaces 26. As shown, the struts I8 reinforce the crowns I5 and I6 and impart desired added rigidity to the assembly without interfering with the flexibility of the ring. The ring is circumferentially expansible and is placed under compression so as to have pressure engagement with the cylinder 29 at all points thereof. Since the ring is flexible, the pressure engagement will be uniform and the ring will be readily conformed to the shape of the cylinder for preventing developement of clearance gaps even as the cylinder becomes worn and out of shape.

The modied ring 40 shown in Figure 9 is formed from a blank 4I shown in Figure 10. This blank is cut or punched to form the slits 42 extending inwardly from the longitudinal edges thereof in the same manner as the slits I2 of blank Il. The slits 42 extend to punched out portions 43 and bisect the transverse centers of these punched out portions. The punched out portions have side walls extending transversely of the strip and merging into parallel slits 44 which extend beyond the inner ends of the adjoining slits 42. The resulting punched blank 4i therefore has segments 45 along one longitudinal edge thereof and similar segments 46 along the other longitudinal edge thereof. The

segments

45 and 46 are in staggered relation with the mid-points of the segments 45 being transversely aligned with the ends of the segments 46. Webs 41 connect the

segments

45 and 46 and are separated by tabs 48 and by the punched out holes 43. The tabs 48 are integrally connected with the mid-points of the

segments

45 and 46 respectively outwardly from the inner ends of these segments.

The blank 4| is bent to form the channel strip 49 of Figures 11 and 12 by folding the blank along the lines Y-Y and by folding the tabs along line ZZ. The strip 49 thus has side flanges or walls composed of the

segments

45 and 46 and end leg portions 41a of the webs 41. The tabs 49 have rounded portions 48a extending from the inner ends of the segments 46 and 41 to flat legs 43h which span the channel and have free ends thrusting against the inner faces of the opposed segments at the cuts 42 between the segments. The free ends of the links 48 therefore span the gaps provided by the cuts 42.

The resulting strip 49 therefore has a channel with side wall segments connected by bridging webs and reinforced by struts lying in a plane radially outward from the webs and alternating with the webs. Gaps 56 are provided between the webs under the struts 48. Since these struts are integrally connected with the segments between the webs, they rigidify the segments against bending or concaving when the ring is stretched or compressed and at the same time thrust against the opposed segments to prevent flexure of the sides of the ring while holding the segments in alignment, thereby eliminating sawtooth effect between adjacent segments.

The

segments

45 and 46 are tapered in the same manner illustrated in Figure 5 to provide the keystone or wedge shape shown in Figure 6 so that the finished ring 40 Will have radial gaps 5| of substantially equal width between the segments to provide for radial compression of the ring.

As shown in Figure I3, the finished ring 40 when seated in the oil ring groove 52 of a piston will have scraping

edges

55 and 56 acting on the cylinder wall 54 at axially spaced levels and the conned channel 51 between these scraping

edges

55 and 56 will have free access to the oil drain hole 58 of the piston through the gap 59 between the webs. The reinforcing struts 48 will rigidify the

segments

45 and 46 without interfering with the flexibility of the ring.

From the above descriptions it should therefore be understood that this invention provides a flexible sheet metal piston ring having a strut reinforced channel and possessing the same flexibility as similar rings not equipped with struts.

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 flexible piston ring comprising upper and lower rings composed of circumferentially spaced segments having active outer scraping edges, circumferentially spaced webs extending radially inward from each segment and thence axially across the space between the segments for connecting the segments in axially and circumferentially spaced relation, struts each having an end integra-l with the central portion of a segment and extending radially inward and thence axially and radially outward between the rings of segments and thence axially into abutting engagement with the end portions of a pair of adjacent segments, said struts lying between said webs and lbeing offset from the webs to provide gaps at spaced intervals around the rings.

2. A resilient piston ring comprsing upper and lower rings of circumferentially spaced segments, circumferentially spaced webs having leg portions extending radially froxn the segments and then axially across the space between the ring portions, and struts displaced radially outward from the axially extending portions of said webs across the space between said rings, each strut having an end portion integral with a central portion of a segment between web portions and having a free end portion spanning the space be- ,Vtween opposite segments and engaging the end portions of these opposite segments, and said struts extending alternately from opposite segments to provide alternate free end portions engaging the axially spaced rings.

3. A piston ring comprising an annular strip of resilient metal having a series of channel deiining segments each including wedge shaped top and bottom crowns and connecting circumferentially spaced U-shaped webs with slots therebetween, said webs having leg portions extending radially inward from the crowns and bight portions extending axially between the leg portions, reinforcing struts between the webs each having one end integral with a crown and extending inward between the leg portions of the adjacent webs and thence diagonally outward to a point radially inward from the radial outer ends of the crowns and thence axially to an opposite free end abutting a pair of adjacent opposed crowns, and said struts extending alternately from opposite crowns.

SAMUEL H. NORTON.

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

UNITED STATES PATENTS Number Name Date 2,273,691 Bowers Feb. 17, 1942 2,296,332 Bowers Sept. 22, 1942 2,421,175 Zahodiakin May 27, 1947 FOREIGN PATENTS Number Country Date 593,392 Great Britain of 1947