More particularly, this invention relates to annular seals of the type for use with a mechanism having linearly or reciprocally movable members.

In a further and more specific aspect, the present invention relates to a seal apparatus having improved means for minimizing fluid leakage between the members and through the seal.

BACKGROUND ART Various mechanical apparatus include first and second members which are substantially coaxial and disposed for relative reciprocal movement. Exemplary are internal combustion engines, positive displacement pumps, pneumatic motors and other mechanical devices incorporating a piston and a cylinder assembly. Further examples will readily occur to those skilled in the art.

Commonly, the cylinder is defined by a bore having a cylindrical sidewall. The piston, a generally cylindrical member, includes a sidewall and a top. An end wall or head, opposing the top of the piston, closes one end of the bore. A chamber of variable capacity is defined within the bore between the head and the top of the piston.

Pressurized fluid functions within the chamber. In an internal combustion engine, the fluid is the expanding gases of combustion, which serve to propel the

piston downwardly or away from the head. Pressurized fluid from an external source is introduced into the chamber of a pneumatic motor to force movement of the piston. In a pump, which is companion to the engine and to the pneumatic motor, fluid is compressed and pressurized within the chamber.

In order to provide for relative movement between the members, it is necessary that the diameter of the piston be of lesser dimension than the diameter of the bore. Frequently, substantial clearance is required.

For example, it is well known that a piston is more sensitive to thermal expansion than is a cylinder.

Accordingly, where heat is a factor, such as in an internal combustion engine, additional space must be provided between the sidewall of the bore and the sidewall of the piston to accommodate thermal expansion of the piston. The space, commonly referred to as sidewall clearance, is generally in the range of fifteen ten-thousandths of an inch to five one-thousandths of an inch, or greater.

For reasons which are immediately apparent to those having an appreciation for the art, it is necessary that the piston be sealed to the cylinder. Conventionally, this is accomplished by a device commonly referred to as a piston ring, an annular seal usually fabricated of metal such as cast iron and having a generally rectangular cross-section. The ring is received within a mating annular ring groove formed into the sidewall of the piston. To facilitate expansion during installation, and for other reasons, the ring is radially severed.

The spacing between the opposed ends of the severed ring, known as the end gap, serves various functions after installation. Having an inherent tendency to expand, the ring maintains tension for attendant sealing

against the sidewall of the cylinder as the bore increases in diameter as a result of wear. The end gap also allows for thermal expansion of the ring resulting from heat generated by friction, compression of fluid, combustion of fuel and other sources.

Although necessary and even beneficial, the end gap is also the source of considerable concern. Normal end gap clearance in a newly installed ring ranges from approximately ten one-thousandths of an inch to approximately forty one-thousandths of an inch. The end gap defines a path for leakage of fluids between the sidewall of the piston and the sidewall of the bore.

Throughout the life of the device, the piston ring continuously expands as compensation for normal wear.

As a result, the end gap ever increases with corresponding increase in leakage, usually referred to as a blow-by.

Efficiency, economy and service life of the apparatus is directly related to blow-by. In general, less than optimum output of the apparatus results from loss of pressure or compression of the fluid. Other deleterious effects are unique to the particular apparatus. In an internal combustion engine, for example, contaminating by-products of combustion suspended in the blow-by gases are carried into the lubricating system which in turn harms components throughout the engine.

In recognition of the desirability of enhancing the seal between the piston and the cylinder, the prior art has proposed various seals which purportedly reduce or eliminate blow-by. Several prior art proposals are direct at attempts to eliminate the end gap in the conventional piston ring. Various proposals include an insert which spans the end gap and is received in a notch formed into the ring on either side of the end

gap. Other proposals include the use of a relatively thin steel member, alternately named a ribbon member or a gap seal member, having a substantially rectangular cross-section. Also advanced is a plurality of severed annular members, installed in stacked arrangement with staggered end gaps. The prior art has also advocated the use of thin steel members, colloquially dubbed rails, in combination with ring members having a general resemblance to conventional piston rings. Being of substantially heavier construction than a rail and usually fabricated of malleable material, such as cast iron, the ring member is variously referred to as a packing member or a sealing ring. The ring member in combination with the rail member comprise a seal assembly of which various embodiments are known.

In accordance with one known arrangement, the rail resides within an annular groove formed into the inner circular wall of the seal member and exerts outwardly directed radial pressure to hold the seal member in contact with the sidewall of the bore. In another configuration, the rail occupies a space between the top of the seal member and the upper radial surface of the containing ring groove. Still other formations orient the radial axis of the rail at an angle.

For various reasons, annular seals of the foregoing character are not perceived as being entirely satisfactory. For example, in an assembly wherein the rail resides within the seal member and exerts an expansive force, excessive friction is generated against the sidewall of the bore. Where only the rail contacts the sidewall, seating or breaking-in of the seal is substantially retarded or even prohibited. An angled rail is subject to vibration, commonly known as ring flutter, when used in connection with a rapidly reciprocating piston. A thin steel member exposed to

extreme heat, such as when utilized as the top compression ring in an internal combustion engine, will become distorted.

Seal assemblies of the above character where devised mainly during the time period ranging from approximately the middle nineteen thirties to early nineteen fifties. During the early nineteen seventies, there was developed a seal assembly which substantially remedied the foregoing deficiencies inherent in the prior art. Distributed by POWERFORMANCE INTERNATIONAL CORPORATION under the trademark TOTAL SEALO, the seal assembly has achieved commercial success, especially for use in connection with four-cycle internal combustion engines.

Briefly, the Total Seal@ device, referred to as a ring set, includes a sealing ring member and a gap seal member. The sealing ring member, a severed annular member preferably fabricated of malleable metal such as cast iron, has thickness and radial dimensions to be received within a conventional piston ring groove in accordance with standard tolerances. Extending inwardly from the outer cylindrical surface along the underside of the sealing ring member is an annular notch in which is received the gap seal member. The intricacies and advantages of the ring are described in U. S. Patent No.

3,811,690 and are well known to those having regard for the art.

Notwithstanding continuing success in the trade, the Total Seal@ ring set has proven to be less than optimum. As installed, the respective end gaps of the sealing ring member and of the gap seal member are diametrically opposed. The elastic expansiveness or outward radial force of a severed annular seal under tension is gradiently distributed throughout.

Therefore, while the set as an assembly is free to move

or work within the ring groove, theoretically, movement between the members should be prohibited as the result of the relative forces therebetween.

Extensive use in testing has shown that occasionally relative movement will occur between the members. The ultimate relative movement is capable of aligning the respective end gaps. While the other advantages of the set remain, leakage can occur.

Considerable research and development has been directed to devising a ring set which will retain the numerous benefits of the present Total Seal@ ring set and yet provide additional benefits and resolve other problems of long-standing in the art. Substantial attention has been directed to an assembly in which the possibility of leakage is minimized. Additional efforts were directed to ameliorating the advantages of the ring set in such areas as reducing generated heat and increasing ring stability. Further consideration has been given to extending the utility of the assembly for use in additional applications, including internal combustion engines having sleeve or port valves and to making practical a piston having a single compression ring.

It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.

Accordingly, it is an object of the present invention to provide improved means for sealing between a pair of coaxial components having relative reciprocal movement therebetween.

DISCLOSURE OF THE INVENTION Briefly, to achieve the desired objects of the instant invention in accordance with a preferred

embodiment thereof, provided is a seal receivable within an annular groove having opposed radial surfaces and carried by one of a pair of reciprocally movable members for sealing engagement with the sidewall of the other of the pair of reciprocally movable members. In a preferred embodiment, the seal is generally comprised of an annular member receivable by the groove and severed to define opposing ends and including a contact surface engagable with the sidewall. The annular member further includes means for interlocking the opposing ends together including an engagement element carried by one of the opposing ends and a detachably engagable complemental engagement element carried by another of the opposing ends. Regarding a preferred embodiment, the engagement element may include a tongue and the complemental engagement element may include a groove.

In another embodiment, the engagement element may include a tongue and the complemental engagement element may include a seat, the tongue having a pair of substantially perpendicular contiguous side surfaces, and the seat having a complemental pair of substantially perpendicular contiguous side surfaces for mating engagement with the pair of contiguous side surfaces of the tongue to provide interlocking engagement of the ends of the annular member so as to form a continuous unitary seal and to inhibit the ends from clipping.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and further and more specific objects and advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description thereof taken in conjunction with the drawings in which: Fig. 1 illustrates a fragmentary horizontal

sectional view taken along the ring groove of a typical reciprocating mechanism and especially showing a commercially successful prior art seal assembly installed therein; Fig. 2 illustrates a perspective view of a seal including an annular member severed to form opposing ends, in accordance with a preferred embodiment of the present invention; Fig. 3 illustrates a top plan view of the seal of Fig. 2; Fig. 4 illustrates a fragmented top plan view of the opposing ends of the seal of Fig. 2; Fig. 5 illustrates an enlarged fragmented perspective view of the opposing ends of the seal of Fig. 2; Fig. 6 illustrates a fragmented vertical sectional view of the mechanism of Fig. 1 having the seal of Fig.

2 installed therein; Fig. 7 illustrates a perspective view of a seal including an annular member severed to form opposing ends, in accordance with an alternate embodiment of the present invention; Fig. 8 illustrates a top plan view of the seal of Fig. 7; Fig. 9 illustrates a fragmented top plan view of the opposing ends of the seal of Fig. 7; and Fig. 10 illustrates an enlarged fragmented perspective view of the opposing ends of the seal of Fig. 7.

BEST MODES FOR CARRYING OUT THE INVENTION Turning now to the drawings, in which like reference characters indicate corresponding elements throughout the several views, attention is first

directed to Fig. 1 which illustrates a mechanism including a first member, generally designated by the reference character 20 and a second member, generally designated by the reference character 22, which are disposed for relative reciprocal movement along a linear axis which is substantially perpendicular to the plane of the illustration. The mechanism is typically representative of internal combustion engines, positive displacement pumps, linear fluid actuated motors and similar apparatus in which first member 20 is generally referred to as the cylinder and second member 22 is usually referred to as the piston. First member 20 includes inner cylindrical sidewall 23 which is coaxial with and spaced from outer cylindrical sidewall 24 of second member 22. The space, commonly termed sidewall clearance and herein exaggerated for purposes of illustration, is necessary to ensure relative movement between the members. To retard leakage, the second member 22 is provided with an annular groove 25, commonly known in the art as a ring groove, for the purpose of carrying sealing means. The traditional sealing means is the conventional piston ring.

Chosen for purposes of illustration is the sealing means set forth in United States Patent No. 3,811,690 and commercially distributed by POWERFORMANCE INTERNATIONAL CORPORATION under the trademark TOTAL SEAL@. The Total Seal@ device, actually an assembly, includes a sealing ring member and a gap seal member generally designated by the reference characters 27 and 28, respectively. Sealing ring member 27, preferably fabricated of malleable metal such as cast iron, has thickness and radial dimensions to be received within groove 25 in accordance with standard tolerances.

Analogous to the conventional piston ring, sealing ring member 27 is severed by end gap 29 and has a sealing

surface 30 which engages cylindrical sidewall 23. Gap seal member 28, preferably fabricated of steel, is dimensioned to be received within a notch (not specifically shown) formed in the underside of sealing ring member 27. Gap seal member 28, similar to sealing ring member 27, is severed by end gap 32 and has sealing surface 33 which also engages sidewall 23.

The intricacies and advantages of the above described seal assembly are well known to those having regard to the art. Therefore, it will be appreciated that while the assembly is free to move or work within the ring groove, movement between the members should be theoretically prohibited as the result of the relative forces therebetween. Concern has been expressed, however, that it is possible for the end gaps to align allowing leakage of pressurized fluids through the seal.

The foregoing is set forth for purposes of orientation and understanding in connection with the ensuing description of a preferred embodiment of the present invention. Aspects not fully described will be readily apparent and appreciated by those skilled in the art.

The present invention provides improvements to the above described seal assembly, and to similar sealing means, whereby the possibility of leakage is minimized.

In accordance with a preferred embodiment of the present invention as illustrated in Fig. 2, there is provided a seal generally designated by the reference character 40.

Seal 40 is dimensioned to be received within the conventional ring groove 25 as illustrated in Fig. 6 setting forth a fragmented vertical sectional view of the mechanism of Fig. 1 having seal 40 installed therein in accordance with standard tolerances. With continuing reference to Fig. 6, it is noted that annular groove 25, which is generally rectangular in cross-section,

includes a first radial surface 35, a second radial surface 36, and an axial surface 37. The relative movement between members 20 and 22 occurs in linear directions represented by the double arrowed line A which is parallel to sidewall 23.

Preferably constructed of carbon steel, seal 40, as shown in relevant part in Figs. 2-5, is generally comprised of a unitary annular member 41 having a first radial surface 42, a second radial surface 43, an outer surface 44 and an inner axial surface 45. It will be understood that other materials can be used, such as aluminum, plastic, etc., the material used often depending upon the application. Outer surface 44 functions as a contact surface to sealingly engage with sidewall 23 of first member 20. Outer surface 44 may be heat treated and/or may be coated with chrome or other protective anti-wear or anti-friction coating for the purposes of wear and reduction of friction. However, outer surface 44 may be provided as rounded or arcuate in cross-section if so desired. Typically, the chrome plating may range between two one-thousands and three one-thousandths of an inch.

Annular member 41 is severed to form a pair of opposing ends herein defined as a first end 50 and a second end 51. First and second ends 50 and 51 carry an engagement mechanism comprising an engagement element and a detachably engagable complemental engagement element operative for interlocking ends 50 and 51 together. Regarding the preferred embodiment as set forth in Figs. 2-5, first and second ends 50 and 51 carry a tongue 52 and a groove 53, respectively, tongue 52 being detachably receivable within groove 53 as seen in Fig. 3. While tongue 52 and groove 53 are illustrated as radius shapes, other shapes such s rectangular may be employed.

Seal 40 may be installed in groove 25 and oriented substantially as seen in Fig. 6 with tongue 52 and groove 53 operative to interlock first and second ends 50 and 51 so as to provide seal 40 as continuous so installed. Seal 40 is elastically expansive or biased to exert an outward force toward or against sidewall 23.

The outwardly biased force urges outer surface 44 toward sidewall 23 to sealingly engage outer surface 44 with sidewall 23 while remaining continuous with tongue 52 and groove 53 detachably engaged. Seal 40 is sized to be removably received within groove 25. In accordance with conventional practice the axial dimension, the distance between surfaces 42 and 43, is approximately four one-thousandths to six one-thousandths of an inch narrower than groove 25. This clearance allows seal 40 to move or work within groove 25, and further allowing it to be easily installed and removed.

Seating of seal 40 is accomplished upon installation and no appreciable wear-in is required.

The outwardly directed force of annular member 41 facilitates the sealing engagement of outer surface 44 to sidewall 23, the force against sidewall 23 being borne by axial surface 37. The load bearing contact between seal 40 and the bore is born solely by outer surface 44 in the form of a parallel line. Furthermore, because first and second ends 50 and 51 are lockingly engaged by virtue of the tongue 52 and groove 53 engagement assembly, first and second ends 50 and 51 are prevented from clipping irregularities present upon inner cylindrical sidewall 23 of first member 20 as second member 22 reciprocates.

The various irregularities that may be present upon inner cylindrical sidewall 23 may be superficial surface irregularities, irregularities present in and around apertures formed through inner cylindrical sidewall 23

for permitting the communication of combustible or combusted gases, or the like. Specifically, ports formed in the sidewalls of 2-stroke engines often cause "clipping"if a conventional seal ring rotates so that the gap aligns with the port. The outwardly directed bias of the ring causes corners at the gap to be clipped off as the ring reciprocates past the port. This is conventionally avoided by pinning the ring, a time consuming and expensive operation. Furthermore, pinning prevents rotation of the ring. Rotation is desirable in a piston ring to facilitate even wear. The locking engagement of first and second ends 50 and 51 prevent them from extending a corner which could be clipped while providing an exemplary seal between first and second members 20 and 22.

Over the operating life of the apparatus considered from initial operation to normal time for replacement or rebuild, the diameter of sidewall 23 will somewhat enlarge and the diameter of seal 40 will somewhat decrease. However, no loss in effectiveness of seal 40 or leakage will occur. As sidewall 23 material and annular member 41 material wears away, annular member 41 will continue to expand to maintain the desired seal of outer surface 44 with sidewall 23.

Over an extended period of operation, outer surface 44 of seal 40 will wear down to such a degree causing the sealing efficiency of seal 40 to diminish. At this point in operation, seal 40 may be removed from annular groove 25 and replaced with a new seal to resume operation. Seal 40 is relatively inexpensive and, due to its unitary nature, is very easy to remove and install.

The foregoing embodiment of the invention is especially adapted to be carried by the inner one of a pair of coaxial reciprocally movable members for sealing

against the cylindrical sidewall of the outer of the two members. Exemplary is the seal assembly held in the ring groove of a piston for sealing engagement with the sidewall of a cylinder in an internal combustion engine.

As best shown in Fig. 5, outer surface 44 is substantially planar and terminates with first and second edges 55 and 56 delineating outer surface 44 from first and second radial surfaces 42 (not shown in Fig.

5) and 43. Due to the unitary nature of seal 40, annular member 41 may be biased so as to cause either first edge 55 or second edge 56 to seat or otherwise engage and seal with sidewall 23 if so desired.

Consistent with the foregoing, Figs. 7-10 set forth, in relevant part, the various structural features of an alternate embodiment of a seal of the present invention generally designated by the reference character 60. Having similar structural and functional characteristics as seal 40, seal 60 is dimensioned to be received within the conventional ring groove 25 as previously discussed with seal 40, further details of which will not be further discussed in great detail.

Preferably constructed of carbon steel, seal 60 is generally comprised of a unitary annular member 61 having a first radial surface 62, a second radial surface 63 (shown only in Fig. 7), an outer surface 64 and an inner axial surface 65. Although not specifically shown, outer surface 64 functions as a contact surface to sealingly engage with sidewall 23 of first member 20 as outer surface 44 of seal 40. Outer surface 64 may be heat treated and/or may be coated with chrome or other protective anti-wear or anti-friction coating for the purposes of wear and reduction of friction. Also, outer surface 64 may be provided as rounded or arcuate in cross-section if so desired.

Annular member 61 is severed to form a pair of

opposing ends herein defined as a first end 70 and a second end 71. First and second ends 70 and 71 carry an engagement mechanism comprising an engagement element and a detachably engagable complemental engagement element operative for interlocking ends 70 and 71 together. Regarding a specific embodiment as set forth in Figs. 7-10, first and second ends 70 and 71 carry a tongue 72 and a seat 73, respectively, tongue 72 being detachably receivable within seat 73 as seen in Figs. 8 and 10. In particular, tongue 72 includes a pair of substantially perpendicular contiguous side surfaces 75 and 76 (shown only in Fig. 10), and seat 73 includes an opposing or complemental pair of substantially perpendicular contiguous side surfaces 77 and 78 for mating engagement with surfaces 75 and 76 of tongue 72.

Seal 60 may be installed in groove 25 and oriented substantially as seal 40 shown in Fig. 6 with tongue 72 and seat 73 operative to interlock first and second ends 70 and 71 so as to provide seal 40 as continuous so installed. Seal 60 is elastically expansive or biased to exert an outward force toward or against sidewall 23.

Although not specifically shown, the outwardly biased force urges outer surface 64 toward sidewall 23 to sealingly engage outer surface 64 with sidewall 23 while remaining continuous with tongue 72 and seat 73 detachably engaged. Like seal 40, seal 60 is sized to be removably received within groove 25, and the distance between surfaces 62 and 63, is approximately four one- thousandths to six one-thousandths of an inch narrower than groove 25 in accordance with conventional practice to provide sufficient clearance to allow seal 60 to move or work within groove 25 while allowing it to be easily installed and removed.

Like seal 40, seating of seal 60 is accomplished upon installation and no appreciable wear-in is

required. The outwardly directed force of annular member 61 facilitates the sealing engagement of outer surface 64 to sidewall 23, the force against sidewall 23 being borne by axial surface 37. The load bearing contact between seal 60 and the bore is born solely by outer surface 64 in the form of a parallel line.

Furthermore, because first and second ends 70 and 71 are lockingly engaged by virtue of the tongue 72 and seat 73 engagement assembly, first and second ends 70 and 71 are prevented from clipping irregularities present upon inner cylindrical sidewall 23 of first member 20 as second member 22 reciprocates while providing an exemplary seal between first and second members 20 and 22.

Another important feature of seal 60 is that because tongue 72 and seat 73 interlock so as to make annular member 61 continuous, exemplary sealing may be accomplished notwithstanding the unitary feature of annular member 61. Although annular member 61 will expand as sidewall 23 material and annular member 61 material wear away to maintain the desired seal of outer surface 64 with sidewall 23, tongue 72 will continue to reside within seat 73 to overlap end 71 to maintain the continuity of annular member 61 to correspondingly maintain a seal between first and second members 20 and 22. Nevertheless, seal 60 will eventually succumb to wear and require replacement after an extended period of time.

As best shown in Fig. 10, outer surface 64 is substantially planar and terminates with first and second edges 80 and 81 delineating outer surface 64 from first and second radial surfaces 62 and 63. Due to the unitary nature of seal 40, annular member 41 may be biased so as to cause either first edge 80 or second edge 81 to seat or otherwise engage and seal with

sidewall 23 if so desired.

Various changes and modifications to the embodiment herein chosen for purposes of illustration will readily occur to those skilled in the art. To the extent that such modifications and variations do not depart from the spirit of the invention, they are intended to be included within the scope thereof which is assessed only by a fair interpretation of the following claims.

The present invention has been described above with reference to a preferred embodiment. However, those skilled in the art will recognize that changes and modifications may be made in the described embodiments without departing from the nature and scope of the present invention. Various changes and modifications to the embodiment herein chosen for purposes of illustration will readily occur to those skilled in the art. To the extent that such modifications and variations do not depart from the spirit of the invention, they are intended to be included within the scope thereof which is assessed only by a fair interpretation of the following claims.

Having fully described the invention in such clear and concise terms as to enable those skilled in the art to understand and practice the same, the invention claimed is: