Pipe compression joint

A pipe compression joint assembly (10) comprises a male pipe end (20) having an outwardly-extending annular rib (34), a female pipe end (40) adapted for slidable insertion of the male pipe end (20) therein, a first clamp ring (54) adapted for slidable coupling with the male pipe end (20) and bearing against the annular rib (34), and a second clamp ring (52) fixedly attached to the female pipe end (40). The first clamp ring (54) can be controllably urged toward the second clamp ring (52) after the male pipe end (20) has been inserted into the female pipe end (40) so that the female pipe end (40) deformably engages the annular rib (34) to effect a sealed joint without the use of a gasket.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a compression joint for use in joining conduit segments.

2. Description of the Related Art

Vehicular exhaust systems typically comprise several different metallic components which must be interconnected. For example, the exhaust system can comprise a muffler which is connected to an exhaust manifold upstream of the muffler, and a tailpipe which is connected downstream of the muffler. The connections must be readily separable so that components of the exhaust system that must be repaired or replaced can be easily removed. At the same time, the connection joints must be tight to prevent the escape of exhaust gases through the joints upstream of the discharge end of the tailpipe. Conventional connections typically comprise a butt joint.

Conventional connections frequently utilize a gasket to enhance the seal between the butt-joined metallic components. Changes in temperature of the components can contribute to thermal contraction and expansion, which can compromise a seal without a gasket. However, the temperature of the exhaust gases, which can approach 1800° F., and the corrosive properties of the gases, can cause deterioration of the gasket and the adjacent metallic components, and can result in the fusing of the gasket and components. This can lead to difficulty in separating the components so that the joint can only be separated by cutting the adjoining components apart. This adds to the labor involved in working with the components, and can result in the replacement of components that might otherwise remain serviceable.

There is a need for a joint which it can provide a satisfactory seal without the use of a gasket, which can be readily assembled and disassembled, and which is not subject to excessive corrosion.

SUMMARY OF THE INVENTION

According to one aspect of the invention, an assembly (10) for forming a pipe compression joint comprises a male pipe end (20) having an outwardly-extending annular rib (34), comprising an inward transition portion, wherein the inward transition portion has a radius of curvature capable of deformation, a female pipe end (40) adapted for slidably receiving the male pipe end (20) therein and having a constant diameter portion that terminates at a flared portion capable of deformation, a first clamp ring (54) on the male pipe end (20) for bearing against the annular rib (34), and a second clamp ring (52) fixedly attached to the female pipe end (40) a distance from the flared portion such that the second clamp ring (52) is spaced from the flared portion by at least part of the constant diameter portion. The first clamp ring (54) can be controllably urged toward the second clamp ring (52) after the male pipe end (20) has been received into the female pipe end (40) so that the flared portion of the female pipe bears against the inward transition portion, and one or both of the inward transition portion and the flared portion is deformed to effect a sealed joint without use of a gasket.

According to another aspect of the invention, a pipe compression joint comprises a male pipe end (20) having an outwardly-extending annular rib (34) comprising an inward transition portion, wherein the inward transition portion has a radius of curvature capable of deformation,a female pipe end (40) with the male pipe end (20) slidably received therein and having a constant diameter portion that terminates at a flared portion capable of deformation, a first clamp ring (54) on the male pipe end (20) and bearing against the annular rib (34), a second clamp ring (52) fixedly attached to the female pipe end (40) a distance from the flared portion such that the second clamp ring (52) is spaced from the flared portion by at least part of the constant diameter portion, and at least two adjustable fasteners (56) connecting the first clamp ring (54) to the second clamp ring (52). The fasteners (56) are tightened so that the first clamp ring (54) and the second clamp ring (52) compress the flared portion of the female pipe end against the inward transition portion, wherein one or both of the inward transition portion and the flared portion is deformed to effect a sealed joint without use of a gasket.

DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

Referring now to the drawings, and in particular toFIGS. 1-5, a first embodiment of the invention comprising a compression joint assembly10is illustrated. The compression joint assembly10comprises a male pipe coupling or male pipe end12, a female pipe coupling or male pipe end14, and a clamp assembly16. The compression joint assembly10can comprise a portion of a larger assembly, such as a vehicle exhaust system comprising an exhaust manifold, a muffler, a tailpipe, and other components, which are not illustrated and form no necessary part of the invention. For convenience, only the compression joint assembly10is illustrated in the drawings. In the example shown inFIG. 1, the male pipe end12would be associated with an upstream component, such as a muffler, and the female pipe end14would be associated with a downstream component, such as a tailpipe.

The male pipe end12comprises a male pipe end20comprising a generally annular, pipe-like member having a circular wall22defining a circular channelway24fluidly coupled with an upstream component (not shown).

The circular wall22has a generally constant upstream diameter36. The circular wall22at the downstream terminus of the male pipe end20comprises an expanding outward transition portion26transitioning to a chine portion28, in turn transitioning to an inward transition portion30, and terminating in a straight portion32defining an opening33to the channelway24and having a generally constant downstream diameter38. The chine portion28and the transition portions26,30define an annular rib34extending radially outwardly of the pipe wall22. The outward transition portion26, chine portion28, and inward transition portion30are configured, in part, so that the upstream diameter36upstream of the outward transition portion26is greater than the downstream diameter38downstream of the inward transition portion30.

Preferably, the outward transition portion26has a constant radius of curvature from the pipe wall22to the chine portion28. The chine portion28preferably has a constant radius of curvature between the outward transition portion26and the inward transition portion30. Preferably, the inward transition portion30has a radius of curvature which decreases from the chine portion28to the straight portion32.

The female pipe end14comprises a female pipe end40having a generally constant diameter46somewhat greater than the downstream diameter38. The female pipe end40comprises a pipe wall42defining a channelway44therethrough. The pipe wall42transitions at an upstream terminus to define an opening48. In a preferred embodiment, the pipe wall42terminates in a somewhat flared portion50defining the opening48. The opening48is adapted for slidable receipt of the straight portion32of the male pipe end20for fluid communication of the channelways24,44.

The clamp assembly16comprises a male or first clamp ring54, a female or second clamp ring52, and a plurality of adjustable fasteners56, preferably threaded. The second clamp ring52is a circular ring-like body defining a second clamp ring opening58therethrough having a diameter for slidable receipt of the second clamp ring52over the pipe wall42. A plurality of regularly-spaced ears66extend radially-outwardly from the circumference of the second clamp ring52, each having an aperture70therethrough for slidable receipt of a fastener56. The first clamp ring54is a generally circular ring-like body defining a first clamp ring opening60therethrough adapted for slidable receipt of the first clamp ring54over the pipe wall22. A plurality of regularly-spaced ears64extend radially-outwardly from the circumference of the first clamp ring54, each having a threaded aperture68therethrough for threaded receipt of a fastener56. The number and spacing of the ears64,66can be selected based upon the clamping force desired. As illustrated herein, there are five equally-spaced ears64,66on each clamp ring52,54and five corresponding fasteners56.

The clamp rings52,54are adapted for coupling as hereinafter described. The second clamp ring52is fixedly attached to the female pipe end40proximate the opening48in a suitable manner, such as by welding, brazing, soldering, and the like, so that a longitudinal force applied to the second clamp ring52through the fasteners56and ears66will be transferred to the female pipe end40. Preferably, the distance between the tangent point defining the point of contact of the second clamp ring52with the pipe wall42and the opening48of the female pipe end40is 7-10 mm, identified inFIG. 2as the distance “D.” This separation enables the flaring deformation of the terminus of the female pipe end40as it is urged against the annular rib34.

The first clamp ring54is provided with a radially-curved inner shoulder62having a radius of curvature which is complementary to the radius of curvature of the outward transition portion26. Slidable engagement of the inner shoulder62of the first clamp ring54with the outward transition portion26of the annular rib34will enable a longitudinal force applied to the first clamp ring54to be transferred to the male pipe end20, while enabling the first clamp ring54to be rotated about the circular wall22.

The compression joint is assembled by inserting the straight portion32of the male pipe end20into the opening48of the female pipe end40. The first clamp ring54is rotated to align the threaded apertures68with the apertures70of the second clamp ring52so that the fasteners56can be slidably inserted through the apertures70and threaded into the threaded apertures68. Threading of the fasteners56into the threaded apertures68will controllably urge the second clamp ring52and the first clamp ring54together. Since the second clamp ring52is fixedly attached to the female pipe end40, and the first clamp ring54is held in place by the annular rib34, tightening of the fasteners56will drive the flared portion50of the female pipe end40against the inward transition portion30of the male pipe end20, thereby coupling the male pipe end12to the female pipe end14in a gasket-less compression joint. Preferably, the length of the surface-to-surface contact between the flared portion50and the inward transition portion30is 3 to 5 mm. The number of fasteners56required depends on the diameter of the clamp rings52,54: the smaller the diameter, the fewer the fasteners to a minimum of two. Larger diameters will require more fasteners.

Some deformation of the flared portion50and the inward transition portion30of the annular rib34along the surface-to-surface contact can occur, depending on the force drawing the male pipe end20and the female pipe end40together. The flaring of the female pipe end40will facilitate the continuity of the surface-to-surface contact of the flared portion50with the inward transition portion30, and will minimize the “chisel” effect of driving an unflared pipe wall into engagement with the inward transition portion30.

The male pipe end20and the female pipe end40must be scarfed (i.e. cleaned) along the surface-to-surface contact. Preferably, the fasteners can comprise 8 mm or 10 mm bolts having sufficient strength and durability for the purposes contemplated herein. The 10 mm bolts will typically tightened to a nominal torque of 40 Nm per fastener. The 8 mm bolts must be tightened to a nominal torque of 25 Nm per fastener.

Preferably, the pipe ends20,40are 300-400 series stainless steel having a pipe wall thickness of 1.2-2.0 mm. The clamp rings52,54are preferably the same material as the pipe ends20,40, having a nominal material thickness of 3.8 mm. The clamp rings52,54can comprise a different material, but if so will have a lower coefficient of thermal expansion than the pipe ends20,40in order to maintain the selected clamp load under the greater thermal expansion of the pipe ends20,40.

Grain direction in the pipe ends20,40is important. Grain direction must be longitudinal, i.e. parallel to the longitudinal axis of the pipe ends20,40. This enables thermal expansion to occur primarily in a longitudinal direction, thereby maintaining the seal. If the grain direction is other than longitudinal, repeated thermal expansion and contraction can cause the seal to fail. A longitudinal grain direction can be established during manufacture of the components. In particular, rolled pipe has a longitudinal grain direction.

The annular rib34can be formed by a sizing press, spun, rolled into the tube, or swaged.

The pipe compression joint assembly10described herein can withstand a temperature of up to 1800° F. and pressures of up to 15 psi. The absence of a gasket simplifies the construction and assembly of the connection, and results in a less costly assembly. The connection can be readily disassembled, and is resistant to corrosion and deterioration caused by the exhaust gases and other environmental conditions.

Referring toFIG. 6, a second embodiment of the invention comprising a compression joint assembly10is illustrated. The compression joint assembly10is substantially identical to the compression joint assembly10shown inFIGS. 1-5, except that two fasteners56are provided to connect the first and second clamp rings54,52(only the second clamp ring52is visible inFIG. 6), which are formed with two ears64,66having apertures68,70. The fasteners56can comprise bolts as discussed above.

Referring toFIG. 7, a third embodiment of the invention comprising a compression joint assembly10is illustrated. The compression joint assembly10is substantially identical to the compression joint assembly10shown inFIGS. 1-5, except that three fasteners56are provided to connect the first and second clamp rings54,52(only the second clamp ring52is visible inFIG. 7), which are formed with three ears64,66having apertures68,70. The fasteners56can comprise bolts as discussed above.

Referring toFIG. 8, a fourth embodiment of the invention comprising a compression joint assembly10is illustrated. The compression joint assembly10is substantially identical to the compression joint assembly10shown inFIGS. 1-5, except that the fasteners56are provided with a plurality of nuts72that are threaded onto the fasteners56to connect the first and second clamp rings54,52. In this embodiment, neither aperture68,70are threaded. During assembly of the compression joint the fasteners56can be slidably inserted through the apertures70,68and the nuts72can be threaded onto the fasters56adjacent either clamp ring54,52; as illustrated herein, the nuts72are threaded onto the fasteners adjacent the first clamp ring54.