This invention relates to a coupling device for a fluid pressure system, and in particular a pneumatic system.

Coupling devices are used in pneumatic systems to connect the fluid flow port of an apparatus to a supply line. Typical industrial systems operate at up to 20 bar, and the supply lines are tubes with a diameter between 4 and 16mm (OD), or equivalent imperial sizes. A coupling device usually comprises a housing with terminal portions. One or more terminal portions have tube coupling devices for a supply line, and another has an adaptor sealingly retained on it, so that the fluid flow port can be connected to the adaptor. The adaptor may be for a swivel fitting, in which case it will need to rotate freely on the terminal portion, or a fixed fitting. Different adaptors may require different terminal portions. Further, the housings also need to have different shapes, being elbows, straight connectors or tees, and each configuration of shape and terminal portion is made separately. This means that the manufacturer or user needs to keep very many parts in stock. It would therefore be advantageous for the devices to be modular, so that an adaptor can simply be fitted manually into a port of a standard housing, as required by the user. This requires a standardised way of connecting adaptors, which allows for manual assembly. This is a problem if the system also has to cope with pressures up to or even beyond 60 bar, because a connection which is strong enough to retain and seal the adaptor in the housing at the higher pressure will also require a much greater insertion force.

According to the present invention, a coupling device for a fluid pressure system comprises a housing having a port to receive an adaptor, and a clip for retaining the adaptor in the housing, the clip having an attachment portion by which it is attached to the housing, and a plurality of resilient

legs projecting from the attachment portion, and the adaptor being inserted into the clip, and having a flange adapted to deflect the legs on insertion, and to engage behind the free end of the legs to retain the adaptor in the housing.

The clip provides a simple way of retaining the adaptor in the housing, and enables a modular system to be used, with all types of adaptor being mounted within a standard port.

Where the housing is of plastics material, the clip is also of plastics material. The adaptor may be of brass, although it could also be of plastics. The adaptor will also, carry a seal adapted to engage with the housing.

The clip may be retained in the housing by a grab ring, or by welding. In either case the connection must be strong enough to withstand the forces exerted by high pressures.

The attachment portion of the clip preferably comprises a solid ring, to ensure that it has a sufficiently strong connection to the housing.

In one embodiment the clip has a set of legs of the same length. Preferably four legs are provided, although three or five or more would be possible. Each leg is angled radially inwardly from the attachment portion, and has a hinging portion of reduced thickness adjacent the attachment portion allowing it to deflect as the adaptor is inserted. The free end portion of each leg is preferably of increased thickness, to provide a larger engagement area with the adaptor flange, and sufficient strength to withstand the pressure forces.

The adaptor preferably has a tapering outside surface, terminating in the flange, which projects radially outwards. The taper on the outside surface is complementary to the angle of the legs. The adaptor conveniently carries a seal for engagement with the housing, the seal being positioned outwardly of the flange, so that the seal does not pass through the clip on the insertion of the adaptor.

In another embodiment the clip has a set of two or more auxiliary legs. The auxiliary legs are of the same length as each other, but are preferably shorter than the main legs.

The auxiliary and main legs are preferably arranged alternately round the attachment portion. Conveniently there are three legs in each set. Each leg is similar in construction to a main leg, being angled radially inwardly, and having a hinging portion adjacent the attachment portion, and a free end of increased thickness.

The auxiliary legs provide additional security on assembly of the adaptor into the clip. In particular, the auxiliary legs are adapted to engage behind the flange as the adaptor is inserted, but before the main legs engage. Thus, if the adaptor is not inserted fully and the system is pressurised, the auxiliary legs will prevent the adaptor being blown out of the device by the fluid pressure.

In this embodiment the flange is extended axially, and carries the seal for engagement between the adaptor and the housing. Preferably the auxiliary legs engage behind the flange just before the seal starts to engage with the housing. The engagement of the seal with the housing creates added resistance to insertion of the adaptor, but even if the adaptor is mistakenly not inserted further the auxiliary legs will act to retain the adaptor.

Preferably the clip also has at least one rib on its attachment portion. Each rib projects radially outwards from the outer surface of the ring, and is tapered in the direction of the legs . The rib or ribs ensure that the clip fits tightly in the housing, by accommodating tolerances between the attachment portion and the housing. They crush inwardly as the clip is inserted in the housing.

If the rib or ribs are provided on the embodiment with auxiliary legs they are preferably arranged at the same circumferential position as the centre of the or each auxiliary leg. If the rib or ribs we provided on the embodiment without auxiliary legs they are preferably arranged circumferentially between the main legs.

Various embodiments of the invention are illustrated by way of example in the accompanying drawings, in which:-

Figure 1 is a longitudinal section through a pneumatic coupling device;

Figure 2 is a plan view of a clip of Figure 1 ;

Figure 3 is a section along the line 3-3 of Figure 2;

Figure 4 is similar to Figure 1 but shows a modification;

Figure 5 is a plan view of a second embodiment of a clip;

Figure 6 is a section along the line 6-6 of Figure 5;

Figure 7 is an enlarged view of a detail of Figure 6; and

Figure 8 and 9 show two stages of the insertion of the adaptor.

Figure 1 shows a coupling device 1 for a pneumatic system, designed to operate at pressures up to 60 bar. The device 1 comprises a housing 2 of T-shape, having three ports 3,4,5. The port 3 is shown fitted with an adaptor 6 for connection to a fluid flow apparatus (not shown), while the other two ports 4,5 are empty. Typically, they would house tube coupling devices for a supply line tube.

The housing 2 is of a suitable engineering plastics material such as nylon. The port 3 has a stepped bore 7 to accommodate the adaptor 6, which is of brass, and is retained in the port 3 by a clip 8, and is sealed by an O-ring 9. The clip 8 is located in the bore 7 at a shoulder 10 formed at a step in the bore 7.

The adaptor 6 has an internal through-bore 11, and a stepped external surface 12. The outer end of the adaptor 6 remains outside the housing 2, and includes a threaded connection 13 for connection to fluid flow apparatus and an enlarged portion 14 with a recess 15 for receiving the free outer end of the port 3. The adaptor 6 shown is a swivel fitting, designed to rotate relative to the housing 2.

The inner end of the adaptor 6 is received in the bore 7. Its external surface 12 has a first portion 25 carrying the O-ring 9 which engages sealingly with the bore 7 adjacent the free outer end of the port 3. The external surface 12 then steps down to a cylindrical portion 16 engaging the clip 8, and then a tapered portion 17, terminating in a radially-outward extending flange 18. The inner end of the flange 18 abuts a shoulder 19 at a step in the bore 7.

The clip 8 is of plasties material, conveniently nylon, like the housing 2. The clip 8 has a solid attachment ring 20 by which it is attached to the housing 2, in this case by a metal grab ring 21. The clip 8 also has four legs 22 projecting from the ring 20, and angled radially inwardly. Each leg 22 has a hinging portion 23 of reduced thickness adjacent the ring 20, which allows the leg 22 to deflect resiliently in a radially outward direction. The thickness of each leg 22 then gradually increases towards its free end, which provides an abutment 24 for the outer end of the flange 18.

In use, the clip 8 and grab ring 21 are inserted into the housing port 3. The O-ring 9 is then assembled on the adaptor 6, which is inserted into the port 3. The flange 18 moves freely until it engages with the start of the legs 22. Further movement deflects the legs 22 radially outwardly, with the legs flexing about the hinging portion 23. This increases the insertion force slightly, and it is further increased as the O-ring 9 enters the bore 7. At the end of its insertion movement, the flange 18 becomes free of the legs 22, which then snap back resiliently to their original, unstressed positions, so that the outer end of the flange 18 engages the abutments 24 on the legs 22. The movement of the legs 22 to their original positions will make a click, providing an audible indication that the adaptor 6 is properly inserted.

When the system is pressurised the O-ring 9 will maintain the seal between the housing 2 and the adaptor 6, while the clip 8 serves to retain the adaptor in the port. The clip 8 is designed so that the legs 22 have sufficient strength to retain the adaptor 6 up to pressures of about 60 bar.

The attachment ring 20 and the grab ring 21 are also designed to ensure that the clip remains attached to the housing 2 for the same range of pressures. However, the insertion force is still relatively low, allowing manual insertion. This is provided by ensuring that the O-ring does not

have to be inserted a great distance, and by the flexing of the legs 22 at the hinging portion.

It will be appreciated that the adaptor 6 is non-removably mounted in the housing 2.

Figure 4 is similar to Figure 1 , but shows a modified way of attaching the clip 8 to the housing 2. Corresponding reference numerals have been applied to corresponding parts .

In Figure 4 the grab ring 21 is omitted. Instead the solid attachment ring 20 is extended axially, and is welded ultrasonically to the housing 2 at a step in the bore 7. Otherwise, the construction and operation of the embodiment of Figure 4 are the same as that of Figure 1.

Figures 5 to 9 show a modification of the adaptor clip of Figures 1 to 4, and corresponding reference numerals have been applied to corresponding parts.

In the modification the first portion 25 of the adaptor 6 (shown in Figures 8 and 9) has a reduced axial length, leading to an inclined portion 26 which accommodates the grab ring 21. The flange 18 is of increased axial length, and has a recess 27 for receiving the O-ring 9. The flange 18 and O-ring 9 are received when assembled (as shown in Figure 9), in a bore portion 32 of the housing bore 7.

The clip 8 has six legs: a set of three main legs 22 and a set of three auxiliary legs 28. The legs 22 and 28 are arranged alternately round the circumference of the solid attachment ring 20. The main legs 22 have the same construction as the legs 22 of the embodiment of Figure 1, while the auxiliary legs 28 are similar but shorter in length, and of reduced

thickness in comparison with the main legs 22. Thus, each auxiliary leg 28 projects from the attachment ring 20, and is angled radially inwardly. Each leg 28 also has a hinging portion 29 to allow the leg 28 to deflect resiliently in a radially outward direction, and a free end which provides an abutment 30 for the outer end of the flange 18.

It will however be noted from Figure 5 that, because the auxiliary legs 28 are shorter than the main legs 22, the circle on which their free ends lie is of greater diameter than the circle on which the free ends of the main legs lie. As a result, the auxiliary legs 28 are not deflected as much as the main legs 22 on insertion of the adaptor.

The clip 8 also has three ribs 31, provided on the radially outer surface of the ring 20, one at the centre of each auxiliary leg 28. As best seen in Figure 7, each rib 31 tapers towards the legs 22, 28 and is designed to be crushed radially inwardly as the clip 6 is assembled in the housing 2. As in Figure 1 , the clip 6 is held in the housing 2 by a grab ring 21.

In use, the clip 8 and grab ring 21 are inserted into the housing port 3, until the clip 8 reaches the shoulder 10 in the bore 7. The ribs 31 will be crushed, to provide a tight or even interference fit in the housing, thus accommodating any tolerances. The O-ring 9 is assembled on the adaptor

6, which is then inserted into the port 3. The flange 18 moves freely until it engages with the start of the legs 22, 28. Further movement deflects the legs 22, 28 radially outwardly, with the legs flexing about their respective hinging portions. This increases the insertion force slightly. Just before the O-ring 9 enters the bore portion 32, flange 18 becomes free of the auxiliary legs 28, which then move back to their original, undeflected positions, so that the abutments 30 engage behind the outer end of the flange 18. At this point the main legs 22 are still deflected by the flange 18. Because the amount of movement of the

auxiliary legs 28 back to their original positions is relatively small, they do not make an audible noise.

This stage of insertion is shown in Figure 8. It will be appreciated that, when the O-ring 9 enters the bore portion 32, the insertion force will increase again. If the person assembling the device 1 mistakes this for the fully-inserted position, the adaptor will remain in the position shown in Figure 8. If the system is pressurised, the pressure will tend to blow the adaptor 6 out of the housing 2, but this will be prevented by the engagement of the auxiliary legs 28 with the flange 18.

Full insertion of the adaptor is shown in Figure 9, with the O-ring 9 sealing in the bore portion 32, and the main legs 22 clear of the flange 18, and having moved back to their original unstressed positions. The movement of the legs 22 does make a click, to indicate full insertion of the adaptor 6.

The embodiment of Figures 5 to 9 otherwise operates in the same way as that of Figure 1.

The use of the clip 8 to attach the adaptor 6 to the housing 2 enables a standardised range of fittings to be used, so that a modular system is possible.