AU8077998A

AU8077998A - A conduit coupling mechanism

Info

Publication number: AU8077998A
Application number: AU80779/98A
Authority: AU
Inventors: Gary Paul Nicholson
Original assignee: Victor Industrial Equipment Pty Ltd
Current assignee: Victor Industrial Equipment Pty Ltd
Priority date: 1997-08-26
Filing date: 1998-08-19
Publication date: 1999-03-11
Also published as: GB2330246A; GB9817414D0; GB2330246B

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): VICTOR INDUSTRIAL EQUIPMENT (PROPRIETARY)

LIMITED

Invention Title: A CONDUIT COUPLING MECHANISM

I

j The following statement is a full description of this invention, including the best method of performing it known to me/us: -2 Ii BACKGROUND TO THE INVEN THIS invention relates to a conduit c to a conduit coupling mechanism fo: S' conduits incorporating flame-proof pi Traditionally, electrical conduit coupl proof plugs and sockets have been ba operating in conjunction with a cam.

to a complementally threaded apertur of engagement with the socket. In dis the threaded conrod is automatically d conrod only once the electrical contac of the electrical contacts, a flame-proc designs, the dimensions of the cam I interfacing dimensions relating to th SABS 1489.

SEngagement of the coupling takes pi the opnosite direction. The fully eng;

'ION

oupling mechanism, and in particular r coupling and decoupling electrical ug and socket arrangements.

ing mechanisms incorporating flamesed on a threaded withdrawal conrod The threaded conrod is rotated relative e so as to move the plug into and out engagement, a floating cam carried on isengaged on continued turning of the :ts have separated. Prior to separation f connection is maintained. In certain i, its axial travel, and various other e flame-proof path are laid down in .ce by rotating the threaded conrod in aged position is generally only reached once the threaded conrod has been completely rotated into the complemental socket. In many cases, the conrod is only turned to an intermediate semiengaged position, thereby reducing the contact area for current flow, leading to over-heating and arcing between the contacts.

i- 4: i:: i;: I* I l~crcl~ -3 In addition, during disengagement, although the flame-proof connection may exist, the existence of water within the connection may create a conduction path leading to sparking and the like. This may in turn lead to an explosive separation of the coupling as soon as the cam is automatically disengaged.

SUMMARY OF THE INVENTION According to the invention there is provided a conduit coupling mechanism for coupling and decoupling mating portions at the respective ends of two lengths of conduit, the mechanism comprising a connector mounted to one of the mating portions, a latching handle connected pivotably to the connector about a first axis, and retaining means mounted slidably relative to the connector for retaining the other of the mating portions, the handle being pivotable about the first axis between a fully engaged position in which the mating portions of the conduit are fully engaged, and a retracted position, in which the mating portions are retracted but retained via the retaining means, and the handle being further pivotable about a second axis from the retracted position to a fully disengaged unretained position in which the retaining means is fully disengaged from the other of the mating portions.

Preferably, the second axis is coaxial with the axis of the connector.

Conveniently, the latching handle is parallel to the second axis in the fully engaged position and is perpendicular to the second axis when pivoting about the second axis between the retracted and fully disengaged unretained positions.

-4- The connector is preferably mounted fast with one of the mating portions.

A manually operable catch may be provided for selectively locking the handle in the fully engaged position.

Conveniently, the catch is arranged to temporarily detain the latching handle in an intermediate restrained position between the engaged and retracted .ositions, in which the mating portions are joined, the latching handle being j movable to the retracted position on release of the catch.

The retaining means preferably includes a locking cam carried on the end of a linkage joining the handle to the retaining means, the locking cam being pivotable about the second axis into and out of engagement with a complemental slot carried on the other of the mating portions.

Advantageously, the conduit is a flameproof electrical conduit having a Splurality of high voltage pin terminals carried on one of the mating portions, a plurality of high voltage socket terminals carried on the other of the i mating portions, and a flameproof path defined between the mating portions of the lengths of conduit, the flameproof path only being broken on complete disengagement of the pin and socket terminals.

Conveniently, the conduit coupling mechanism includes a pilot pin terminal carried on one of the mating portions, and a pilot socket terminal carried on the other of the mating portions, the pilot pin and socket terminals being arranged to complete pilot circuit which is arranged to cut off a power supply to the high voltage pin and socket terminals on disconnection of the pilot terminals.

STypically, the pilot pin terminal is arranged to be disconnected from the pilot socket terminal somewhere between the engaged and retracted positions.

4 Preferably, the pilot pin terminal is arranged to be disconnected from the pilot socket terminal in the intermediate restrained position.

BRIEF DESCRIPTION OF THE DRAWIINGS Figure 1 shows a partly cross-sectional side view of part of a conduit coupling mechanism of the invention in a locked and fully engaged position; Figure 2 shows a cross-sectional side view of the conduit coupling mechanism of Figure 1 in an unlo':ed position; Figure 3 shows a cross-sectional side view of the conduit coupling *mechanism of Figures I and 2 in an intermediate position; Figure 4 shows a cross-sectional side view of the conduit coupling mechanism of Figures 1 to 3 in a partly disengaged or Srestrained position; and Figure 5 shows a cross-sectional side view of the conduit coupling mechanism of Figures 1 to 4 in the fully disengaged or decoupled position.

q IF I I Ir M V Y r' U~*i~.iliLlu~;r~i.jr~i~~~6~' ~Sj~~i -6- DESCRIPTION OF EMBODIMENTS Referring first to Figure 1, a conduit coupling mechanism 10 of the invention is arranged to act between a plug portion 12 and a socket portion 14. In Figure 1, the plug portion 12 is shown fully engaged within the socket portion 14, with a flame-proof path 16 being fully established at the interface between the respective plug and socket portions in accordance with SABS 1489. The plug portion 12 includes a three-phase high voltage supply lines terminating in socket terminal contacts, one of which is shown at 17A, together with a pilot circuit including a lower voltage socket terminal contact 17B. The socket portion 14 in turn includes three high voltage pin terminal contacts, one of which is shown at 17C, and a corresponding pilot pin terminal contact 17D. It can clearly be seen in the Figure 1 closed position that the pin and socket terminal contacts are fully engaged.

The coupling mechanism includes a locking cam 18 having a projecting cammed surface 20 which locates within a complemental detent 22 defined within the plug portion 12. The locking cam 18 is mounted to a linkage 24 in the form of a joined pair of cheek plates 24A and 24B (see Figure 5) via a pivot axle 26. The linkage 24 is in turn mounted pivotably about a pair of pivot axles 28 proximate one end of a latching handle 30. The handle is in turn mounted pivotably via an axle 32 to a mounting block 34 which straddles a conrod 36. The mounting block 34 is held in position by means of a nut 38 which is screwed onto a threaded end of the conrod, together with a compression spring 40 which acts between the mounting block 34 and the nut 38 so as to allow for variations in length. The latching handle 30 is arranged to rotate around the pivot axle 32, and the locking cam 18 is arranged to move axially relative to the conrod 36. A catch 42 is pivoted r apt:- g ~,c rF'i~ r' r- i n~-ra

T.

.A 14 A MJ 9 4. 6 JA L WL- 1.0 ji-- bo -7at 44 to the latching handle, and is biased by means of a torsion spring 46 so that its free end 47 abuts the linkage 24 so as to retain the latching handle in the closed position illustrated in Figure 1. The catch 42 is formed with a projecting end 48 having an aperture 49 for receiving a padlock to lock the catch and the handle in the Figure 1 closed position.

In order to release the latching handle, the padlock (not shown) is unlocked so as to allow the projecting end 48 of the catch to be pressed downwardly, i thereby releasing the free end 47 of the catch from the linkage 24 and .allowing the latching handle 30 to be lifted upwardly to the unlocked position illustrated in Figure 2. In this position, the latching handle 30 is shown partly rotated about the pivot axle 32, with rotation of the handle causing the pivot axles 28 of the linkage to describe an arc about the pivot axle 32. This action results in the locking cam 18 travelling axially in the direction of arrow 50 relative to the conrod 36. The conrod 36 terminates in a threaded portion 52 which is screwed into a complementally threaded passageway 56 formed within the body of the socket portion 14. A stop S formation 58 on the conrod 30 controls the depth of the entry of the threaded portion 52 within the passageway 56. In this manner, the coupling mechanism is mounted fast to the socket portion 14 of the conduit. Axial movement of the locking cam in the direction of arrow 50 thus causes the plug portion 12 to start separating from the socket portion 14.

Figure 3 illustrates an intermediate position in which the pivot axles 32 and 26 are moved closer to one another via the linkage 24. The free end 47 of the catch travels along an arcuate guide track 60 defined in the linkage 24 until it abuts a stop 61 which restricts further movement of the coupling mechanism until such time as the. projecting end 48 of the catch 42 is

O.

W. the stop 61. In the Figure 3 intermediate position in which the catch 42 is arrested by the stop 61, the corresponding distance dl between the plug and socket portions 12 and 14 is sufficient to ensure that the pilot plug terminal 17D is completely disengaged from the pilot socket terminal 17B. In this position, the phase socket and pin terminals 17A and 17C are still fully engaged. Disconnection of the pilot plug and socket terminals will in turn cause the pilot circuit to cut off the power supply to the three phase high voltage supply via power control circuitry. As a result, in the Figure 3 position, no current is flowing through the high voltage terminals 17A and 17B, thereby eliminating or at least reducing any risk of arcing due to separation under load. In the Figure 3 position, the flame path 16 is still established.

Once the catch 42 has been released from it intermediate restrained position in Figure 3, the latching handle can now be moved towards the disengaged restrained position illustrated in Figure 4, in which it is approximately perpendicular to the main axis of the plug and socket connection. It can clearly be seen from Figures 3 and 4 how the distance between the plug and socket portions 12 and 14 progressively widens from dl to d2. In the Figure Sdisengaged restrained position, the plug portion 12 is shown1. thim of its axial travel, with the flame-proof path 16 still being established, and the plug and socket portions 12 and 14 still being mechanically engaged.

The latching handle 30 is then rotated by a quarter turn about the axis of the Svconrad to the Figure 5 fully decoupled position. At the e time, the locking cam 18, which is rigidly connected to the handle 30 via the linkage 24, is rotated a quarter turn so that the cammed projection 20 is moved free of the detent 22, as can clearly be seen at 58. In this position, the plug Slocking cam 1, which is rgidly connected to the handle 30: via the linkge b v- 1 9 portion 12 is now uninhibited, and can be fully withdrawn from the socket 14.

The coupling sequence is exactly the reverse of the decoupling sequence described above.

There are five main actions required to withdraw the plug from the socket, namely removal of the padlock and initial depression of the catch 42, pivoting of the latching handle to the Figure 3 intermediate position, Ssubsequent depression of the catch 42, further pivoting of the handle in the same plane normal to the axis 32 to the Figure 4 disengaged restraining position, and subsequent pivoting of the latching handle in a perpendicular plane normal to the conrod axis so as to release the locking cam. As a result, the condition of the coupling interface can be assessed between the pilot circuit disconnection, the phase disconnection and the fully disengaged Sdecoupling steps. For example, if the phases are still live when the position in Figure 3 is reached in the unlikely event of the pilot or power control circuitry malfunctioning, an unsafe condition will be evident without risk of exposing the live contacts.

Naturally, the conduit coupling mechanism is not restricted to the coupling of electrical conduits, but may also be used to couple conduits carrying fluids, including pressurized gases and liquids, in which case the locking cam serves a restraining function to prevent the plug and socket portions from blowing apart under pressure.

A further advantage of the invention is that the latching mechanism ensures complete engagement of the plug and socket when in the fully coupled or I' "-2 -s c4~ de r M V -1 1 9 1 1 M 111 cad. J6 6 IIY~~1131~ t~L~IIU~-PCI-C C~ ~P 10 engaged Figure 1 position. This is in contrast to a prior art screw-in conrod in which the conrod can easily be left in an intermediate position in which overheating and arcing can occur. The coupling mechanism also decreases the overall time taken to perform coupling and decoupling, whilst still maintaining sufficient mechanical advantage to ensure that the handle can be easily operated, and incorporating additional safety steps.

As can be seen in Figure 2, a further advantage of the coupling mechanism is that it can easily be retro-fitted to existing coupling assemblies utilizing the previously described prior art threaded conrod and socket arrangement, of which the threaded passageway 56 forms a part.

i.

r r j+ fi r ~qs r P71E. rr n k r 1 ?w r 1*

Claims

1. A conduit coupling mechanism for coupling and decoupling mating portions at the respective ends of two lengths of conduit, the mechanism comprising a connector mounted to one of the mating portions on one of the lengths of conduit, a latching handle connected pivotably to the connector about a first axis, and retaining means mounted slidably relative to the connector and engageable S'"with the other of the mating portions for retaining the other of the mating portions, the handle being pivotable about the first axis conduit are fully engaged, and a retracted position in which the mating portions are retracted but retained via the retaining means, and the handle being further pivotable about a second axis from the I retracted position to a fully disengaged unretained position in which the retaining means is fully disengaged from the other of the mating portions.

2. A conduit coupling mechanism according to claim 1 in which the second axis is coaxial with the axis of the connector. S3. A conduit coupling mechanism according to claim 2 in which the latching handle is parallel to the second axis in the fully engaged position and is perpendicular to the second axis when pivoting about the second axis between the retracted and fully disengaged unretained positions.

4. A conduit coupling mechanism in which the connector is mounted WTI'g i "M .TOW 12 fast with one of the mating portions. A conduit coupling mechanism according to any one of the preceding claims which includes a manually operable catch for selectively locking the latching handle in the fully engaged position.

6. A conduit coupling mechanism according to claim 5 in which the catch is arranged to temporarily detain the latching handle in an 1 intermediate restrained position between the engaged and retracted positions, in which the mating portions are joined, the latching handle being movable to the retracted position on release of the catch.

7. A conduit coupling mechanism according to claim 6 in which the retaining means includes a locking cam carried on the end of a linkage joining the handle to the retaining means, the locking cam being pivotable about the second axis into and out of engagement Swith a complemental slot carried on the other of the mating portions.

8. A conduit coupling mechanism according to any one of the preceding claims in which the conduit is a flameproof electrical conduit having a plurality of high voltage pin terminals carried on one of the mating portions, a plurality of high voltage socket terminals carried on the other of the mating portions, and a flameproof path defined between the mating portions of the lengths of conduit, the flameproof path t only being broken on complete disengagement of the pin and socket terminals.

9. A conduit coupling mechanism according to claim 8 which includes f Ir 1 I 13 a pilot pin terminal carried on one of the mating portions, and a pilot socket terminal carried on the other of the mating portions, the pilot Spin and socket terminals being arranged to complete pilot circuit Swhich is arranged to cut off a power supply to the high voltage pin 4 and socket terminals on disconnection of the pilot terminals. A conduit coupling mechanism according to claim 9 in which the pilot pin terminal is arranged to be disconnected from the pilot socket terminal somewhere between the engaged and retracted positions. S11. A conduit coupling mechanism according to claim 10 in which the Spilot pin terminal is arranged to be disconnected from the pilot socket terminal in the intermediate restrained position.

12. A conduit coupling mechanism substantiall. as herein described and illustrated. Dated this 19th day of August 1998 VICTOR INDUSTRIAL EQUIPMENT (PROPRIETARY) LIMITED By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent Attorneys of Australia r