GB2157382A - Releasable pipe coupling - Google Patents

Abstract

A terminal unit 1 for medical gases includes a releasable latching mechanism comprising a coil spring 14 having two spaced parallel portions 15, 16 which in the relaxed condition of the spring 14 extend into the interior of the terminal unit. The portions 15, 16 engage behind an abutment on a probe 50 when inserted into the terminal unit. In order to release the probe cam members 42 on a ring forming part of a cap assembly 25 are moved relative to the portions 15, 16 to thereby separate the portions 15, 16 and force them out from the interior of the terminal unit 1 thereby to release the probe 50. <IMAGE>

Description

SPECIFICATION Improvements in gas supply systems The present invention relates to gas supply systems and in particular to medical gas terminal units.

It is common practice in hospitals to install centralised distribution systems for gases such as air, oxygen and nitrous oxide. The gases are distributed from a central location via pipes to terminal units located in operating theatres, wards and the like. When it becomes necessary to supply, for example, an anaesthesia unit with a gas then a probe which terminates a flexible hose connected to the unit is releasably plugged into an appropriate terminal unit and the gas is automatically supplied to the anaesthesia unit.

Matching terminal units and probes are colour coded and/or dimensioned or in some other way keyed so that the danger of inserting a probe terminating an oxygen line into a terminal unit supplying, for example, nitrous oxide is substantially eliminated.

It is an aim of the present invention to provide a terminal unit for gases which has few parts and is inexpensive to produce.

It is a further aim of the present invention to provide a terminal unit in which minimum effort is required to insert a probe and the removal of the probe can be achieved by minimum effort in either or a combination of two distinct movements.

According to the present invention a terminal unit for gases comprises a tubular housing for the passage therethrough of a gas, a coil spring having a portion which, in a first position of the spring, extends through a slot in the housing for releasably latching a probe when operatively inserted in one end of the housing, means carrying at least one cam member and mounted for movement on the housing between a first inactive position and a second position at which the cam member engages the spring and forces said portion outwardly from the interior of the housing thereby disengaging the portion from the probe.

Preferably, the coil spring has a generally straight portion at each end, the portions being spaced apart and generally parallel to each other across one end face of the coil, each portion in the first position of the spring extending through an individual slot in the housing.

The means may be in the form of a ring which carries two cam members spaced apart diametrically on the ring, each cam member extending between the parallel portions of the coil spring.

An embodiment of the invention will now be described, by way of example, reference being made to the Figures of the accompanying diagramatic drawings in which: Figure 1 is a longitudinal cross section through a pendant terminal unit for gases illustrating two positions of a probe partially and fully inserted into the terminal unit; Figure 2 is an end view of a coil spring forming part of the terminal unit of Figure 1; Figure 3 is a side view of the coil spring of Figure 2; Figure 4 is a side elevation of a tubular housing forming part of the terminal unit of Figure 1; Figure 5 is a longitudinal cross section through a cap forming part of the terminal unit of Figure 1; Figure 6 is an end elevation of the cap of Figure 5 but showing in dotted lines the coil spring of Figures 2 and 3 in position relative to the cap;; Figure 7 is a side view of a sub-assembly including the tubular housing, coil spring and a ring forming part of the terminal unit of Figure 1.

Figure 8a is a sketch illustrating the relationship between various parts of the terminal unit in a normal position with the coil spring relaxed; Figure 8b is a sketch illustrating the relationship between various parts of the terminal unit in a position where portions of the coil spring are moved apart by pushing on the cap of Figure 5; and Figure 8c is a sketch illustrating the relationship between various parts of the terminal unit in a position where portions of the coil spring are moved apart by rotating the cap of Figure 5.

As shown in Figure 1, a pendant terminal unit 1 has a hollow rear member 2 having a tubular tail piece 4 over which fits, in a gas tight manner, a flexible conduit or pipe leading from a central location for the distribution of a gas, for example, oxygen. Located within the rear member 2 is a spring loaded valve assembly 6 including a valve head 7 which, as will be explained, controls the flow of oxygen through the terminal unit 1.

The rear member 2 has, at its front end (right-hand end as shown in Figure 1 ) a flange 8 to which is bolted the flange 10 of a tubular housing 12. Between the rear member 2 and the rear end of the tubular housing 12 is a tubular retaining member 11 a portion of which extends into the rear member 2 and locates one end of a tubular guide member 13 extending between the rear member 2 and the tubular housing 12. The rear end (lefthand end) of the tubular guide member 13 acts as a valve seat when co-operating with the valve head 7. The inner surface of the tubular guide member 13 tapers inwardly from its front end and immediately adjacent its front end is counterbored to receive an Oring seal 70.

Referring also to Figure 4, the tubular housing 12 includes an intermediate cylindrical boss 18 extending forwardly from the flange 10. Further, extending forwardly from the boss 18 is another smaller boss 20 and at the interface of the bosses 18, 20 there are formed two diametrically opposed slots 22.

Both slots 22 extend through the wall of the tubular housing 12. Internally, the tubular housing 12 has a rearwardly facing shoulder 17 which engages the front face of the retaining member 11 and a second rearwardly facing shoulder 19 which with anti-extrusion ring 21 locates the forward end of the guide member 13.

Referring also to Figures 2 and 3, a coil spring 14 at each end has a generally straight portion 15, 16. The portions 15, 16 are spaced apart and generally parallel and extend across the rear end face (left-hand end as shown in Figure 1) of the coil 14. The portions 15, 16 are located respectively in a slot 22 on the tubular housing 1 2. In the relaxed state of the spring 14, each portion 15, 16 extends along and through its respective slot 22 and into the interior of the tubular housing 12.

Referring also to Figures 5 and 6, a cap 24 forming part of a cap assembly 25 comprises a right circular cylindrical body 30 having a front end 31. Extending rearwardly from the front end 31 are two spaced annular bosses 32, 33 which define between them an annular pocket 34 which accommodates the coil portion of the spring 14.

The outer boss 32 is formed at its rearend with a counterbore 35. The inner boss 33 is formed with two pairs of rearwardly extending fingers, the fingers of each pair being dia metncaIly#opposed. The fingers 36 are narrower than the fingers 37.

Internally, the cap 24 has a through bore 38 having a keyway 39. The cap 24 is so dimensioned that it renders the terminal unit 1 gas specific, that is, it will only accept a probe with matching dimensions and shape for delivering a specific gas through the probe.

As shown most clearly in Figures 1 and 6, the fingers 36 and 37 extend over the surface of intermediate boss 18 whilst the fingers 36 also pass between the parallel portions 15, 16 of the coil spring 14.

The cap assembly 25 includes means in the form of a ring 40 which is a close fit in the counterbore 35 of the cap 24. The ring 40 carries two diametrically opposed cam members 42 extending forwardly and between the parallel portions 15, 16 of the coil spring 14.

The cam members 42 are similar and taper outwardly from adjacent the main body of the ring towards their free ends (see Figure 7).

Each cam member 42 extends over a flexible finger 36.

In use, when it is desired to provide a gas to an anaesthesia unit, a probe 50 terminating the flexible hose from the anaesthesia unit is inserted or plugged into a terminal unit 1 via the through bore 38 in the cap 24. At maximum insertion the end of the probe 50 engages the valve assembly 6 and forces it rearwardly so that the valve head 7 is separated from its cooperating seating at the rear end of the tubular guide 13. Gas will then flow through the rear member 2, past the valve assembly 6 and into the probe 50 towards the anaesthesia unit.

The probe 50 is tapered and is guided during insertion by the tapered internal surface of the tubular guide 13. The outer surface of the probe 50 engages in a gas tight manner the O-ring seal 70 to prevent egress of gas between the opposing surfaces of the probe 50 and tubular guide 13.

During insertion, the tapered nose of the probe 50 moves between the portions 15, 16 of the coil spring 14 spreading them apart until just at full insertion a groove in the probe allows the portions 15, 16 to snap back into the groove and thereby latch the probe 50 in position within the terminal unit 1.

When it is desired to release the probe 50 from the terminal unit 1, this can be achieved in one or other of two ways or a combination thereof (see Figures 8a, 8b and 8c).

(a) The cap assembly 25 can be pushed rearwardly (see Figure 8b) so that the ring 40 with the cam members 42 is moved from a first inactive position, rearwardly, to a second position thereby causing the cam members 42 to spread apart the portions 15, 16 of the coil spring 114. The portions 15, 16 will thus clear the groove in the probe 50 and thereby permit its release.

(b) The cap assembly 25 can be rotated (see Figure 8c) either clockwise or anticlockwise so that each cam member 42 engages a portion 15, 16 and causes it to spread outwardly from the groove in the probe 50 thereby permitting release of the probe 50.

It is evident that a combination of these two movements could be used to achieve the same effect.

Modifications can be made, for example, the ring 40 and the cap 24 need not necessarily be formed as a cap assembly 25 and could exist separately of each other.

The portions 15, 16 need not be precisely straight and parallel but could be slightly curved.

Furthermore, although a pendant terminal unit has been described it will be evident to those familar with the art that a wall mounted terminal unit, for example, could be provided with substantially the same releasably latching arrangement as described in connection with this embodiment.

The particular advantages of the terminal unit 1 as described in the above embodiment are that the elements comprising the releasable latching device are simple to manufacture and assemble and therefore inexpensive to produce. Furthermore, minimal force is required to insert a probe within the terminal unit and minimal force is required to release the probe from the terminal unit. Release of the probe from the terminal unit can be achieved by two distinct movements or a combination of the movements. Furthermore, the particular shape of the coil spring 14 makes it suitable not only for the latching function but also allows the spring to interconnect the cap assembly 25 to the tubular housing 12.

Claims (7)

1. A terminal unit for gases comprising a tubular housing for the passage therethrough of a gas, a coil spring having a portion which, in a first position of the spring, extends through a slot in the housing for releasably latching a probe when operatively inserted in one end of the housing, means carrying at least one cam member and mounted for movement on the housing between a first inactive position and second position at which the cam member engages the spring and forces the portion outwardly from the interior of the housing thereby disengaging the portion from the probe.

2. A terminal unit as claimed in claim 1, in which the coil spring has a generally straight portion at each end, the portions being spaced apart and generally parallel to each other across one end face of the coil, each portion in the first position of the spring extending through an individual slot in the housing.

3. A terminal unit as claimed in claim 2, in which the means is a ring which carries two cam members spaced apart diametrically on the ring, each cam member extending between the parallel portions of the coil spring.

4. A terminal unit as claimed in claim 3, in which the ring forms part of a cap assembly, the cap assembly including a cap having a first annular boss and a second annular boss which define between them a pocket for the coil portion of the coil spring.

5. A terminal unit as claimed in claim 4, in which the ring is a close fit in a counterbore formed in the first outer boss, the cam members extending forwardly into the pocket defined by the first and second bosses.

6. A terminal unit as claimed in claim 5, in which fingers extend from the second inner boss and engage over an outer surface of the tubular housing for sliding movement thereon.

7. A terminal unit for gases constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the Figures of the accompanying drawings.