FIELD AND BACKGROUND OF INVEMTIQN
The present invention relates to pipe couplings, and particularly to pipe couplings of the compression type, such as are described, for example in US Patents 4,025,093 and 4,083,587, assigned to the assignee of the present application.
Pipe couplings of this type generally comprise: a body member formed with a bore for receiving one end of a pipe to be coupled, an annular shoulder to enclose the pipe when received In the bore, and threads for threadedly receiving a securing nut; a sealing ring receivable within the bore and engageable with the annular shoulder for producing a sealing action with respect to the pipe when received in the bore; a compression sleeve also receivable witting the bore and engageable with the sealing ring for compressing the sealing ring against the annular shoulder of the body member; a radlally-deformable gripping ring having one end abuttable against the compression sleeve, and also having an inner surface producing a gripping action within respect to the pipe when the gripping ring is radially deformed; and a securing nut having tirades mating with the threads on the body member and engageable with the gripping ring to move the gripping ring axially and to effect the sealing action via tile impression sieve and the sealing ring, and also to compress the gripping ring radially to effect the gripping action of the pipe received in time bore.
Pipe couplings of the foregoing type will hereinafter be referred to as ''pipe couplings of tike type herein described".
Pipe couplings of the type herein described, which are presently In wide-spread use, normally require pushing the pipe through time seal (typically an 0-ring) in the bore of the body member in order to achieve compression of the 0-rlng on tike pipe, and thus a leak free joint. However, for pipes of large diameters, the operation of pushing the pipe through the 0-ring seal requires a large force, making tile operation very difficult, and sometimes even necessitating an extra operation of chamfering the pipe end for tills purpose.
A fruitier disadvantage in pipe couplings of type herein described now in use is that such couplings do not tolerate substantial variations in the pipe diameter so tilt precise pipe diameter tolerances must be maintained, or a large number of

different-size couplings must be produced for the different diameter pipes to assure good sealing and gripping actions.
OBJECTS AND BRIEF SUMMARY OF THE INVENTION
An object of the present invention Is to provide a pipe coupling having advantages in one or more of the above respects.
According to one aspect of the present invention, there is provided a pipe coupling of the type herein described, characterized in that the pipe coupling further comprises an axially-extending limit element between the gripping ring and the body member effective to cause the nut, when tightened: (a) in an Initial stage, to move the gripping ring and the compression sleeve, and to start compressing the sealing ring, until the limit element prevents further axial movement of the gripping ring; and (b) in a final stage, to radially deform the gripping ring to produce the gripping action, and then to further compressing the sealing ring against the Internal annular shoulder of the body member to produce the sealing action.
Adoring to another respect of the Invention, the sealing ring is Integrally formed on Its surface with at least two annular ribs, one at each end.
According to a still further aspect of the present Invention, there is provided a pipe coupling of the type herein described, wherein the bore in the body member is formed with an annular rib at the end thereof opposite to that formed with the annular shoulder, and the end of the compression sleeve facing the sealing ring is formed with an external rib dimensioned to releasably retain the compression sleeve, and the sealing ring, within the body member bore during the preliminary assembly of the coupling.
As will be described more particularly below, a pipe coupling constructed in accordance with the foregoing features provides a number of important advantages including: convenient assembly, since the particular seal, in its relaxed condition, Introduces very little resistance to the forceful entry of the pipe during assembly; assurance that the pipe end will be properly positioned with respect to the seal to produce a good sealing action, since the pipe end reaches its final position before final tightening of the nut; in eased diameter range of pipes capable of being coupled, since the two-ribbed (or a three-ribbed) sealing ring can accommodate substantial

differences in diameter sizes; Imposed sealing even on damaged pipes, particularly since the seal produces double sealing points; and convenient disassembly of the coupling, since relaxation of the sealing ring releases the pipe end for removal and also ^springs out" the compression sleeve, the split ring and the nut during disassembly.
Further features and advantages of the invention will be apparent from the description below.
BRIEF DESCRIPTIOW OF THE DRAWINGS
The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein:
Rg. 1 is an exploded perspective view illustrating one form of pipe coupling constructed in accordance with the present invention;
Fig. 2 Is an enlarged sectional view illustrating the pipe coupling of Fig. 1 during the initial tightening stage of the securing nut;
Rg. 3 illustrates the pipe coupling of Rg. 1 In the final tightened state of the nut;
Rgs. 4, 5 and 6, are views corresponding to Rgs. 1, 2 and 3, respectively, Illustrating another forni of pipe coupling constructed in accordance with the present Invention wherein the limit elements, in the form of a plurality of fingers, are integrally formed with the body member, rather than with the gripping ring;
Rg. 7 Is a view similar to that of Rg. 4, but showing the fingers Integrally funned on an abutment ring between the body member and the sealing ring;
Rg. 8 is a view similar to that of Rg. 7, but showing the abutment ring between the sealing ring and the compression sleeve; and
Rg. 9 is a view similar to that of Rg. 8, but showing the abutment ring between the gripping ring and the compression sleeve.
PESCMPTIQN OF A EMBOPIMENT The Embodiment of Fiats. 1-3
The pipe coupling illustrated in Rgs. 1-3 is of the type herein described (as defined above) but modified to Include the features of the present Invention set forth above, and as to be described more particularly below. As shown in Rg. 1, such a pipe coupling Includes the following basic parts: a body member 10; a sealing ring 20;

a compression sleeve 30; a gripping ring 40; and a securing nut 50. Fig. 2 illustrates ties parts in an initial assembled condition; and Rg. 3 illustrates these parts in the final assembled condition.
Body member 10 Is preferably of plastic, but may be of knottier material e.g., metal. It is formed with a bore 11 for receiving one end of a pipe P to be coupled, and with an Internal annular shoulder 12 for defining the position of the pipe when received within bore 11. Bore 11 is enlarged in diameter at its outer end, as shown at 13, for receiving the sealing ring 20 and the compression sleeve 30, as will be described more particularly below. This enlargement in the bore also defines an annular shoulder 14 which limits the position of the sealing ring 20. The inner surface of body member 10 at the enlarged end 13 of bore 11 is formed with an annular rib 15 for releasably retaining the compression sleeve 30, and with it the sealing ring 20, during the initial assembling of the coupling, as will also be described below. The outer edge of enlarged bore 13 Is chamfered, as shown at 16, to facilitate tiie Insertion of the sealing ring 20 and compression sleeve 30.
Body member 10 is further formed with external threads 17 on Its outer surface, at the end facing the securing nut 50, for securing the parts together.
The sealing ring 20 is made of elastomeric material. Preferably, it is of an Inner diameter slightly larger than the outer diameter of title pipe P to be coupled, but may also be equal to or slightly smaller than the pipe diameter, in order to accommodate variations In the diameter of the pipes.
Sealing ring 20 is Integrally formed on its outer surtaxes with at least two, preferably tired, annular ribs 21, 22, 23. The two end ribs 21, 23 are of substantially semi-circular cross-section. The middle rib 22 is optional, since it serves to prevent collapse of tike sealing ring. When provided. It preferably Is of substantially biangular cross-section. The Inner surface 24 of sealing ring 20 Is smooth but Is rounded at Its opposite ends, as shown at 25 and 26.
The compression sleeve 30 Is preferably also of plastic material, e.g., of the same material as tine body member 10, but may also be of another material, e.g., metal. It has an Inner diameter slightly larger than time outer diameter of the pipe P to be coupled. The end of compression sleeve 30 facing body member 10 is preferably chamfered on Its inner and outer surfaces, as shown at 31 and 32, respectively. In

addition, Its outer surface Is formed with a shallow annular rib 33 at the end of the sleeve feeing body member 10. Rib 33 is cooperable with rib 15 of the body member to releasably hold the compression sleeve, and with It tine resilient ring 20, during the assembling of the coupling.
The opposite end of the compression sleeve 30, I.e., the end facing the gripping ring 40, is formed with a radial flange 34 having a plurality (In this case three) axially-extending slots or recesses 35 spaced around its periphery, for reasons to be described below. The Inner surtaxes of flange 34 facing the gripping ring 40 is Inwardly tapered in the direction of the gripping ring, as shown at 36 In Figs. 2 and 3.
The gripping ring 40 Is made of a hard, elastic plastic material, such as an acetyl resin. It Is formed with a slit 41 extending axially for the complete length of the ring to make It radially deformable. Its inner surface is formed with annular barbs or ribs 42 adapted to penetrate the outer surface of the pipe P when the ring is radially contracted. The outer surfece of split ring 40 is formed with a plurality of axlally-extending circumferentially-spaced ribs 43 of Inaeaslng height joined to an annular rib 44 at the end of the split ring 40 facing the compression sleeve 30.
The end of gripping ring 40 facing compression sleeve 30 is further formed with a plurality of axlally-extending projections 45, serving as axlally-extending limit elements between the gripping ring 4 and the body member 10. These limit elements 45 are in the form of fingers and are effective to assure that, during the tightening of the nut 50 as will be described below, first the sealing ring will be parity compressed to produce a seal, then the gripping ring will be compressed to flinty grip the pipe Inserted Into the body member, and finally the sealing ring will be more firmly compressed to assure a good seal, even when using a sealing ring of slightly larger diameter than the outer diameter of the pipe to facilitate Insertion of the pipe.
There Is one finger 45 for each of the recesses 35 funned In flange 34 of the compression sleeve 30. Each finger 45 includes an outwardly-extending shoulder 46 at its outer tip. The Inner surfece of each finger 45 is outwardly tapered in the direction of the compression sleeve 30, as shown particularity in Rgs. 2 and 3. The outer surfaces of the ribs 43 of gripping ring 40 are tapered, decreasing in height towards the nut 50.

Nut 50 includes a cylindrical section 51 facing body member 10, and a conical section 52 fading away from the body member. The inner surface of nut section 51 is formed with threads 53 to mate with thread 17 on the body member; and the inner surface of section 52 is tapered, as shown at 54, corresponding to the taper of the outer surface of the ribs 43 of the split ring 40. The inner surface of nut 50 is further formed with an annular shoulder 55 at the juncture of its two sections 51 and 52. Nut 50 is further formed with a bore 56 of slightly larger diameter than the pipe P to be coupled.
The Illustrated coupling may be used in the following manner for coupling a pipe P.
First, nut 50 Is loosened by rotating it in the loosening direction, i.e., away from the body member 10, sufficiently to relax the gripping ring 40 and also the sealing ring 20. In the relaxed condition of the gripping ring 40, the inner diameter of Its barbs 42 Is slightly larger than (nut may be equal to or even slightly smaller than) the outer diameter of time pipe P to be coupled; and similarity in the relaxed condition of the sealing ring 20, its Inner diameter 24 is also slightly larger than the outer diameter of the pipe P to be coupled.
The pipe P may then be easily inserted via bore 56 of nut 50 with a relatively small amount of force, until the end of the pipe abuts against the Inner annular shoulder 12 of the body member 10 (Fig. 2).
Nut 50 is then rotated in the tightening direction, moving its Inner tapered seriate 54 axlally towards the body member 10. During the initial axial movement of nut 50, it moves axlally the compression sleeve 30 and the sealing ring 20 towards annular shoulder 14 of body member 10 to start the compression of the sealing ring. Gripping ring 40 Is still In Its relaxed condition when shoulders 46 of fingers 45 of the gripping ring are still slightly spaced axlally from the end of body member 10, as shown in the upper part of Fig. 2.
This Initial tightening of nut 50 continues until shoulders 46 of the gripping ring fingers 45 abut the end of body member 10. This continues the compression of tiie sealing ring 20. Also, the gripping ring 40 is no longer able to move axlally of the pipe P, such that further tightening of the nut causes the tapered surface 54 of the nut to radially contract the split-ring 40 and to embed its barbs 42 into the outer

surface of pipe P. This radial defomiation of gripping ring 40 produces a finn gripping action between it and the pipe.
Continued rotation of nut 50 moves the compression sleeve 30 axially of the pipe, by virtue of the engagement of shoulder 55 of the nut flange 34 of the compression sleeve, thereby moving the compression sleeve towards shoulder 14. This further compresses the sealing ring 20 against the annular shoulder 14 of body member 10, to produce a firm sealing action, as shown in Rg. 3.
For disassembling the pipe P, it is only necessary to rotate nut 50 in the loosening direction, permitting the pipe P to be pulled out of the coupling.
It will thus be seen that the Illustrated coupling provides a number of Important advantages. Since the sealing ring 20 in its relaxed condition can be made of larger diameter than the pipe P to be inserted, a pipe may be easily inserted into the coupling and through the seal. Also, since the pipe is more freely inserted through the sealing ring, there is better assurance that the end of the pipe P will be in Its proper position, fimily abutting annular shoulder 12 of body member 10, before the final tightening of the nut 50 which effects the firm gripping of the pipe.
The Illustrated coupling also produces an excellent seal since It provides two sealing points on tiie outer surface with respect to the body member, and a sealing surface of substantial area on Its Inner surface with respect to the pipe P. The described seal produces a substantial displacement of both its inner and outer sealing surfaces, allowing for a relatively large sealing strol