GB1579987A

GB1579987A - Ball joint coupling

Info

Publication number: GB1579987A
Application number: GB8208/78A
Authority: GB
Original assignee: Aeroquip AG
Current assignee: Aeroquip AG
Priority date: 1977-03-11
Filing date: 1978-03-02
Publication date: 1980-11-26
Also published as: IT1101840B; FR2383384B1; NL7802650A; BR7801481A; IT7848391A0; SE7802748L; JPS53113321A; DE2810238A1; DE2810238C2; FR2383384A1

Description

(54) BALL JOINT COUPLING (71) We, AEROQUIP AG, a Corporation organized under the laws of Switzerland, of of Bahnhofstrasse 17, Zug, Switzerland, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention generally relates to ball joint couplings and methods of sealing them.

In the past, ball joint couplings employed in elevated temperature and pressure piping systems have been sealed by placing gaskets between the ball and socket portions of the joint wherein the gaskets have been conventionally formed from metallic or nonmetallic materials. When metallic gaskets are employed to seal the joint they must be machined to close tolerances and then lapped to the mating ball to form a seal. However, when the mating surfaces of either the metal gaskets and/or ball is scratched or becomes corroded in service, leakage of the joint occurs. The nonmetallic gaskets conventionally used in sealing a ball joint coupling are generally molded from asbestos, silicone, or phenolic compositions which are highly susceptible to assuming a permanent compressive set, particularly when subjected to elevated temperatures and pressures. When such gaskets take a permanent set, the initial preload on the coupling assembly is lost and the coupling will leak when the temperatures and pressures in the piping system are reduced. In both cases, leakage from the ball joint coupling is stopped by replacing the gaskets. This generally necessitates removing the ball joint coupling from the piping system which, of course, is costly and time consuming.

A major disadvantage of the above described ball joint couplings is that the preload required in holding the conventional gaskets in sealing engagement is so high that flexing of the coupling is inhibited.

An object of this invention is to provide a ball joint coupling having universal movement, flexes easily under minimal forces and which remains fluid-tight in spite of variations of movement between the parts of the coupling at elevated temperatures and pressures.

Another object of the invention is to provide a ball joint coupling with bearings which form part of a sealing chamber but require no lapping or mating of parts for forming a seal.

Yet another object of the invention is to provide a ball joint coupling with an interior chamber which is filled with a sealing compound having a plastic state and wherein the chamber can be recharged with additional sealing compound without removing the ball joint from the piping system.

Still another object of the invention is to provide a ball joint coupling with a sealing compound that remains in a plastic state at high and low temperatures, assumes no permanent compressive set and protects the component parts of the coupling from corrosion at elevated temperatures.

The accompanying drawing is a perspective view, partly in section, of a ball type coupling assembly embodying the invention According to one aspect of the invention we provide for use in elevated temperature and pressure piping systems, a method of sealing a ball joint coupling having a spherical ball portion supported by a pair of bearings within a surrounding casing, characterised by providing a closed chamber between the spherical ball portion, the pair of bearings and the casing, and completely filling the closed chamber with a sealing compound which intimately contacts the pair of bearings so that said coupling is sealed thereby during use.

According to another aspect of the invention we provide a ball joint coupling of the type having a spherical ball portion surroun- ded by a casing, characterised by a pair of bearings mounted in said casing and shaped to make intimate contact with said spherical ball portion, said bearings being located one on each side of the spherical center line of said ball portion and in contact with respective ends of said casing, said bearings supporting said spherical ball portion in a radially spaced relationship relative to said casing and being located in a position whereby said bearings, said spherical ball portion and said casing define an interior chamber, and a sealing compound completely filling the chamber and intimately contacting said bearings and said spherical ball portion for sealing said coupling while in use Although the ball joint coupling constructed in accordance with this invention is' par- ticularly suited for use in high temperature piping systems, it also is suitable for use in cold temperature piping systems.

Referring now to the accompanying drawing, a ball joint coupling designated in its entirely by the reference numeral 10, is constructed of a tubular member 11 having a spherical ball portion 12 which is positioned in one end of a casing member 13. The casing member 13 is formed with a cylindrical bore 14 containing the ball portion 12 with the bore 14 ending in an annular abutment or shoulder 15. An inner ring-type bearing 16 bears against the shoulder 15 and has an internal, spherical surface 17 which engages the inner part of the external spherical surface of the ball portion 12. On the opposite side of the spherical center- of the ball portion 12, there is provided an outer ring-type bearing 18 which also has an internal spherical surface 19 for engaging the outer part of the external spherical surface of the ball portion 12.

The inner and outer bearings 16 and 18, respectively, preferably are constructed from a durable material such as cast iron and each has an outside diameter whereby it intimately engages the interior surface of the casing 13 forming the bore 14. The bearings 16 and 18 support the ball portion 12 in a radially spaced relationship relative to the interior surface of the casing 13, for a purpose which will be described hereinafter.

The outer end of the casing 13 includes a rigid outwardly projecting flange member 20.

The flange 20 carries a plurality of bolts 21 which extend axially through a retainer ring 22 having an axially extending annulus 23 which is drawn into engagement with the outer bearing 18 by progressively tightening nuts 24 which are spaced from the retainer ring 22 by lock washers (not shown). Accordingly, the bearings 16 and 18 are urged into intimate contact with the spherical ball portion 12 on opposite sides of its center since the inner bearing 16 is seated on the shoulder 15 of the casing 13 and the outer bearing 18 is urged theretowards by the retainer ring 22.

Since the bearings 16 and 18 are not employed for sealing, the only preload required from the bolts 21 is that which removes axial movement between them and the spherical ball portion, 12.

The retainer ring 22 surrounds the tubular portion of the member 11 and has an annular tapered opening 25 which is large enough to give the tubular member 11 adequate freedom to move universally relative to the casing 13.

An important feature of this invention lies in the arrangement of the bearings 16 and 18 which support the ball portion 12 in the casing 13. More specifically, the opposed surfaces of the ball portion 12, the casing 13 and the opposed faces of the inner and outer bearings 16 and 18, respectively, define an annular chamber 26 which is filled with à sealing compound. To this end, the casing 13 is provided with a pair of tapped apertures 27 which open into the chamber 26. The apertures are normally diametrically opposed but for the sake of clarity are shown with a 90 degree spacing therebetween. Each tapped aperture 27 receives a socket head pipe plug 28 for closing the chamber 26 once it is filled with the sealing compound.

The sealing of the ball joint coupling 10 which utilizes the metal bearings 16 and 18 to the extent that they form part of the chamber 26, is obtained by filling the chamber 26 with a sealing compound 29 which remains in a plastic state at high as well as low temperatures. The filling of the chamber 26 with the sealing compound may be accomplished with a grease gun, ram screw or other similar device. On occasions, it may be desirable to fill the chamber 26 with the sealing compound by injecting the sealing compound thereinto and holding it under pressure. Thus conventional zerk fittings (not shown) may be employed in place of the pipe plugs 28.

Additional sealing compound can be added to the ball joint 10 at any time by simply removing the pipe plugs 28 and recharging the chamber 26 to maintain a seal between the parts of the coupling.

A desirable sealing compound is one which remains in a plastic state at extremely elevated temperatures over prolonged periods of time and flows under pressure, which pressure will force the compound into any potential leak paths in the joint assembly.

Further, the sealing compound is one that will not harden or set at extremely elevated temperatures. It has been discovered that a sealing compound composed of approximately 21 percent asbestos, 13 percent aluminum and 66 percent phenolic resin is particularly effective to seal the joint 10 when it is injected into and held under sealing pressure in the chamber 26. Further, it has been discovered that this sealing compound does not attack or destroy the metal surfaces of the joint assembly; rather, it acts as a rust inhibitor and protects and preserves the moving surface of the ball joint assembly 10.

Also, it has been found that a sealing compound of the above-mentioned composition does not volatilize, bake hard or shrink at elevated, temperatures or pressures.

The utilization of the metal bearings 16 and 18 in the ball joint assembly 10 also has the advantage in that movement of the ball portion 12 in the bearings 16 and 18 tend to burnish the bearing surfaces to a point where the surfaces between the ball portion 12 and the bearings 16 and 18 tend to provide a secondary seal.

WHAT WE CLAIM IS:- 1. For use in elevated temperature and pressure piping systems, a method of sealing a ball joint coupling having a spherical ball portion supported by a pair of bearings within a surrounding casing, characterised by providing a closed chamber between the spherical ball portion, the pair of bearings and the casing, and completely filling the closed chamber with a sealing compound which intimately contacts the pair of bearings so that said coupling is sealed thereby during use.

2. A method of sealing a ball joint coupling as claimed in Claim 1, characterised in that said sealing compound has the properties of remaining in a plastic flowable state, not hardening or shrinking at elevated temperatures and pressures, being nonvolatile, and inhibiting corrosion.

3. A method of sealing a ball joint coupling as claimed in Claim 1 or Claim 2, characterised by providing a pair of access apertures opening into said closed chamber, filling said chamber through said access apertures with a sealing compound and closing said access apertures.

4. A ball joint coupling of the type having a spherical ball portion surrounded by a casing, characterised by a pair of bearings mounted in said casing and shaped to make intimate contact with said spherical ball portion, said bearings being located one on each side of the spherical center line of said ball portion and in contact with respective ends of said casing, said bearings supporting said spherical ball portion in a radially spaced relationship relative to said casing and being located in a position whereby said bearings, said spherical ball portion and said casing define an interior chamber, and a sealing compound completely filling the chamber and intimately contacting said bearings and said spherical ball portion for sealing said coupling while in use.

5. A coupling as claimed in Claim 4 including means in said casing for providing access to said chamber for filling the same with said compound.

6. A coupling as claimed in Claim 4 or Claim 5, characterised by means for closing said means providing access to said chamber.

7. A coupling as claimed in Claim 6, characterised in that said closing means comprise pipe plugs.

8. A coupling as claimed in any of claims 4 to 7 characterised in that said pair of bearings comprises an inner ring-type bearing and an outer ring-type bearing with said bearing being positioned between an interior surface of said casing and the external surface of said spherical ball portion on opposite sides of its spherical center-line.

9. A coupling as claimed in any of claims 4 to 8, characterised in that said bearings are formed of cast iron material.

10. A coupling as claimed in any of claims 4 to 9 characterised in that said sealing compound is of the type that remains plastic and does not harden or shrink at elevated temperatures and pressures and is flowable under pressure.

11. A coupling as claimed in any of claims 4 to 10, in which said bearings comprise an inner and an outer bearing respecitvely, said inner bearing is held fast by said casing and said spherical ball portion, and said outer bearing is mounted in and axially movable relative to said casing, and including a retainer having a portion in contact with said outer bearing and another portion securable to said casing for holding said bearings in intimate contact with said spherical ball portion and securing said bearings in said casing.

12. A method of sealing a ball joint coupling substantially as described with reference to the accompanying drawings.

13. A ball joint coupling substantially as described with reference to, and as shown in, the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. burnish the bearing surfaces to a point where the surfaces between the ball portion 12 and the bearings 16 and 18 tend to provide a secondary seal. WHAT WE CLAIM IS:-

1. For use in elevated temperature and pressure piping systems, a method of sealing a ball joint coupling having a spherical ball portion supported by a pair of bearings within a surrounding casing, characterised by providing a closed chamber between the spherical ball portion, the pair of bearings and the casing, and completely filling the closed chamber with a sealing compound which intimately contacts the pair of bearings so that said coupling is sealed thereby during use.