US 3346264 A
Description (OCR text may contain errors)
Oct.`10, 1967 D, w, HAMM 3,346,264
OIL RINGS Filed Jan. 18, 1965 INVENTOR. l' AZ A44/VM ATTORNEYS United States Patent O M 3,346,264 OHL RINGS Douglas W. Hamm, Muskegon, Mich., assigner to Muskegon Piston Ring Company, Muskegon, Mich., a corporation of Michigan Filed .lan 18, 1965, Ser. No. 426,023 2 Claims.. (Cl. 27T- 141) This invention relates to piston rings, and more particularly to an oil ring consisting of an assembly of an expander and a pair of case or molded sections.
Combination oil rings of this general type have been known and used for a number of years. Rings of this ygeneral type also are shown in my co-pending application, Ser. No. 212,297, entitled Piston Rings, tiled July 25, 1962, now Patent No. 3,191,946, over which this invention is an improvement. In the past, it has been known to assemble an expander .and a single cast or molded section to form an oil ring of this type. 1n come cases, plural sections have been used. In both cases, the sections and the expander were not pre-assembled prior to installation. In other words, the ring groove was the means by which the sections and the expander were held together. These arrangements were not entirely satisfactory,
The assembling of a number of separate and independent components into a ring at the time of installation all too frequently leads to improper installation. Sometimes, the expander and the section or sections become misaligned in the installation process. Sometimes, the ends of the expander do not properly butt together. This results in subsequent malfunction. Many costly auxiliary devices have been devised to prevent this misalignment. This invention uses the ring structure for this purpose. Also, the problem of holding the several components together in proper relationship during the actual installation process significantly slows the installation process and thereby, materially increases its costs. This invention overcomes these problems.
The invention permits the use of plural sections in an arrangement in which they are pre-assembled and locked together so that they can be installed `as a unilied assembly. This speeds up the installation process and eliminates the possibility of misalignment due to improper installation. This is an important contribution to improved performance and increased service life.
The use of plural sections in a ring of this type has a number of advantages. It permits each section to have different characteristics. For example, one of the cast sections may be left plain on the cylinder contacting surface, while the other may be chrome plated. This reduces the initial cost of the ring. It also permits the plain section of the ring to serve as a quick seating early sealing element during initial break in. This is possible because the plain section, being softer on the wear surface, will wear more rapidly than the plated section to :a conforming shape with the cylinder wall. Thus, a seal will be formed during the extended period required for the plated section to wear in and seat, Thereafter, the plated section having a substantially harder, wear resistant surface will take over as the durable, long-life sealing member. This produces a ring having both quick seating and extended surface life characteristics.
. This effect is possible with this ring since the invention provides an assembled ring in which the two sections are permitted a limited amount of radial movement independent of each other. Thus, the unplated or softer section can shift radially with respect to the plated section to effect proper seating against the cylinder walls as it wears in. Further, since each of the cylinder Wall contacting crowns is free to shift radially with respect to the other, a slight irregularity of one of the crowns 3,346,264 Patented Oct. 10, 1967 lCe or of the cylinder wall will not restrain the entire ring from proper seating, this also contributes to the sealing efficiency of the assembly.
The manufacture of this type of ring is less costly than the conventional cast section because a single mold will produce bot-h halves or sections. This permits higher production for a given mold cost. Further, the separate sections are thinner. This reduces the possibility of warpage due to variations in the composition or temperature of the metal during pouring and cooling. There is less tendency toward build-up of internal stresses.
Oil rings of this t-ype must have venting holes extending radially through the central portion of the ring to drain lubricants which become trapped between the cylinder wall engaging crowns of the cast or molded sections. In conventional one-piece constructions, these must either be formed by cores within the mold when the ring is initially cast or molded, or they must thereafter be formed by side machining or slotting of the ring. Frequently, both operations are performed on a single ring. This invention permits these vent openings to be cast molded or machined into the sepa-rate sections of the ring without the use of cores. One half of each opening is usually formed in each section. This is done by the configuration of the side of the mold, rather than by the use vof cores, and thus, materially reduces the cost of the mold, as well as the set-up time necessary to prepare each mold. Any machining on these openings can be done directly on the exposed side face of the ring section. This operation is easier and less costly to perform. Since the opening is formed between two components which have some freedom to shift with respect to each other, their repeated movement during operation tends to prevent the accumulation of carbon deposits.
Because the sections are thinner, and thus more ilexible, the sections have greater conformability than is possible with the single cast section type of ring. This, together with the independent action of the multiple pieces, improves the sealing qualities of the ring.
These and other advantages and purposes of this invention will be understood by those acquainted with the design and installation of piston rings upon reading the following specification and the accompanying drawings.
In the drawings:
FIG. l is a fragmentary, plan view of a ring embodying this invention;
FIG. 2 is a fragmentary, enlarged, front elevation View of a ring embodying this invention;
FIG. 3 is a sectional, elevation view taken along the plane III-III of FIG. 2, illustrating the ring installed in a ring groove;
FIG. 4 is an exploded, sectional view of the ring assembly;
FIG. 5 is a sectional, elevation View taken along the plane V-V of FIG. 2, omitting the expander; and
FIG. 6 is a fragmentary, oblique view of the expander.
The inner component of the ring consists of a sinuous expander of generally U-shaped cross section. The legs of the U extend radially and their ends are turned toward each other to form locking flanges. The central portion of the ring is formed by `a pair of cast or molded sections preferably of identical construction. Each of these sections has a cylinder wall engaging crown. Adjacent its inner radial face, the axial height of the section is reduced, and an annular, axially extending channel is formed in the side of the section. By circumferential sliding movement, the expander is assembled with the two sections, thus pressing them together and holding them against any substantial radial displacement with relation to eachy other. In this assembly, the locking flanges enter the annular channels for the purpose of locking the sections together in a unified assembly. It is also possible to snap the expander on to the sections `as a method of assembly. To facilitate this the upper inner corners of the segments are beveled at 43 (FIG. 4).
Referring specifically to the drawings, the numeral l@ indicates a ring having a pair of cast or molded sections ill and IZ, and an expander f3. Each of the sections llil and I2 has a shape somewhat like a attened Z. The outer radial face has an annular crown 2@ which makes the sealing contact with the cylinder wall 5f) as indicated in FIG. 3. The inner portion of the face has a recess 2l forming a relief of annular shape in the outer face of the ring. The upper, inner, radial corner of the ring is recessed at 22 to receive the expander i3. The recess 22 communicates with the upper end of an annular channel 23. T he channel 23 extends axially into the section. At spaced intervals, the ring has vent openings 26 elongated circumferentially and extending from the base of the recess 21 through to the inside face of the ring (FIGS. l and 2). These recesses preferably are for-med in two parts or halves, one in each section with the vent opening being finally formed when the two sections are assembled as a unit. Thus, each half of the vents 26 may be cast or machined in the face of the section, rather than being cut into the face of the ring as is conventional in a one-piece ring of this type. If it is desired to machine this opening after castng, this can be done wth relative ease since each half of the opening is readily accessible on the exposed side surface of the section.
Both of the sections Ill and I2 are parted as is indicated at 3i) in FIG. 1. The sections, being identical as illustrated, seat against one another along a parting line 3f. located at the axial midpoint of the ring.
The expander I3 is formed from a single strip of metal and is of one-piece construction having a part 4t) at one point (FIG. l). The inner radial bight portion of the expander consists of a plurality of circumferentially, equally spaced, axially extending struts 4f. Adjacent pairs of struts are integral on one end with radially extending, segmentlike legs 42. The segmentlike legs 42 on opposite sides of the expander are offset with respect to each other. Thus, the two struts integral with one of the seg-mentlike legs 42 on one side of the expander are integral with two adjacent segmentlike legs on the opposite sides of the expander. This produces a zigzag-type construction which has sufficient circumferential compressibility to permit the unit to function as a spring capable of generating a significant amount of radial tension when the part til is closed and the spring is deiiected.
The ends of each of the segmentlike legs d2 are bent over, producing a pair of anges 4-3, one on each side of the expander. The iianges 43 on the opposite sides of the expander are directed toward each other. These are designed to seat in the channels 23 of the sections Il and lf2, when the two sections are assembled together. The length of the segmentlike legs 42 is such that the struts 4f are spaced radially inwardly from the inner face of the assembled sections Ill and IZ. The radial width of the channels 23 is such that each of the sections lll and I2 is permitted a limited degree of radial travel without undue restraint `from the flanges 43. This feature is most important to permit the sections lll and I2 to have freedom to adjust with respect to each other, and with respect to the cylinder wall.
It will be noted that the axial height of the expander f3 is slightly less than that of the assembled sections II and I2. This eliminates contact between the expander and the sides Si of the ring groove 52. This is important to effect proper side sealing. The radial depth of the ring assembly is less than that of the ring groove, preventing bottoming.
This limited relative radial movement permits the sections to have different wear characteristics, and thus, be capable of performing functions which normally are in conflict with each other when the section is a single uniform casting. For example, in FIG. 5, the face of the cro-wn 2t) of the upper section lill may be plated with a suitable, highly wear resistant material such as chromium or molybdenum indicated by the layer 23. The outer face of the crown 20a of the lower section l2 may be used without plating of any type. Another possibility is to plate the crown 2t) with chromium and the crown 20a with molybdenum as suggested by the layer 29 in FlG. 5.
Either one of these exemplary procedures will produce cylinder wall engaging surfaces having a marked difference in wear in characteristics and rates. Chromium being an extremely hard material wears slowly and the initial wear in process requires an extended period of time. During this period, the sealing qualities of the ring are frequently poor or at best, mediocre, due to the fact that proper seating of the ring with the cylinder walls has not taken place. On the other hand, a molybdenum coated ring or a cast iron ring with no coating-at all will wear in and effect the desired seating at a substantially faster rate. Therefore, the lower section 1.2 will tend to `wear in and effect a proper seal early in the break-in period, and give the ring a highly satisfactory performance characteristics at an early date. Later on, the hardened surface of the section II will complete its wear in period and will take over the job of effecting a proper seal. Because of its hardness, it wlil continue to perform an acceptable sealing function over a substantially greater service life than the section l2. Thus, the ring is capable of performing what otherwise would be basically conicting performance objectives. These objectives cannot be obtained with a single cast section since the harder crown would hold the softer crown away from the cylinder wall-preventing early seating.
Since the two sections llll and I2 may shift radially relative to each other, each section will be free to conform to the cylinder wall irrespective of the performance of the other section. It is also important that the sections being thinner are, therefore, more flexible and capable of a higher degree of conformance than would be `a single massive section. This also materially improves the rings overall sealing efficiency. Further, should there be, for any reason, a failure of one of the sections, it is quite likely that the other section will continue to give a reasonably acceptable degree of performance for an extended period. rI`his would not ybe true of the entire cast portion if this ring were `a single integral unit. This can be an important factor in increasing the acceptable life of this type of oil ring.
The expander can be made heavy enough, yet flexible enough, to give the desired radial tension and withstand the temperatures incident to the operating environment of this type of ring, reducing the amount of heat set. Such an expander will have capability of retaining its predetermined degree of resilience over a long operating life.
It will be recognized that While a preferred embodiment of this invention has been described, that other embodiments of this invention may be made without departing from the principles of the invention. Such modifications are to be considered as included in the hereinafter appended claims, unless these claims, by their language, expressly state otherwise.
il. A combination oil ring having a main body portion and a circumferentially compressible, parted expander; said body portion having a pair of parted cast sections each forming a significant part of the body portion and adapted to seat against each other in side-to-side sections and each having a cylinder engaging crown on its radially outer face and an axially extending channel in its exterior side adjacent its radially inner face; said expander being of U- shaped cross section having a web portion and a pair of legs with said legs extending radially outwardly; the ends of said legs having opposed fianges seating in said channels, one in the channel of each section and locking said sections together in alignment and against subsequent separation `axially of the ring while permitting circumferential movement of one section with relation to the other;
said web portion being spaced radially inwardly from the radially inner lfaces of said sections; said expander when the part therein is closed and compressed exerting radially outwardly acting pressure on said sections; said channels being wider than the thickness of said flanges and each of said sections having limited freedom of radial movement independent of the other of said sections.
2. A combination oil ring as described in claim 1 wherein the crown of one of said sections has a surface characterized by substantially greater wear resistance than the crown of the other of said sections with said other section serving as a rapidly formed seal 0n initial operation and said one section serving as a slow wearing durable seal thereafter, said sections independently shifting radially to compensate `for the differential in Wear rate of their crowns.
References Cited UNITED STATES PATENTS 5 2,305,276 12/ 1942 Rushmore 277-195 2,313,395 3/1943 Phillips 277-229 X 2,330,550 9/1943 Bowers 277-200 2,640,746 6/1953 Phillips et al 277-193 X 3,191,946 6/1965 Hamm 277-140 X 10 3,202,430 8/1965 Braendel 277-141 X LAVERNE D. GEIGER, Primary Examiner. I. S. MEDNICK, Assistant Examiner.