WO2006037965A1

WO2006037965A1 - Tube coupling cap

Info

Publication number: WO2006037965A1
Application number: PCT/GB2005/003767
Authority: WO
Inventors: Michael Roberts
Original assignee: Norgren Limited
Priority date: 2004-10-01
Filing date: 2005-09-30
Publication date: 2006-04-13
Also published as: GB0421835D0

Abstract

A cap for a tube coupling, the coupling comprising a body (2) having a terminal portion for receiving a tube (3), sealing means (4) for sealingly engaging the external surface of the tube (3), tube gripping means (5) for gripping the external surface of the tube (3) to retain it in the body (2), and release means (35) that extends from the terminal portion of the coupling (1) and which, upon actuation, acts on the gripping means (5) to enable the removal of a tube (3) from the coupling, wherein the cap (40) comprises a mounting portion (41) for mounting it to the body (2) and a cover portion (42) that partially covers the terminal portion of the coupling and abuts the release means (35), the cover portion (42) being resiliently flexible such that application of a force to the cap (40) causes it to deform.

Description

TUBE COUPLING CAP

This invention relates to a cap for mounting on a tube coupling and, in particular relates to a protective cap having a tamperproof feature restricting the manual operation of the coupling to which it is mounted. The invention is particularly applicable to tube couplings in a pneumatic system.

Pneumatic systems comprise pneumatic lines to transfer the pneumatic fluid as well as pneumatically operated devices that are powered or controlled by the pneumatic fluid. Tube coupling devices and fittings are used in pneumatic systems to connect pneumatic lines together, in order to alter their direction or make up longer lengths, and also to connect them to fluid flow ports of pneumatically operated devices. Such coupling devices usually comprise a body having a terminal portion to receive the end of a tube forming part of a pneumatic line, and gripping means and sealing means for the tube. The tube is normally inserted by hand through the gripping means, which is normally a grab ring or collet, and the sealing means, which is typically an O-ring, until the end of the tube reaches a stop provided in the body.

The gripping means may have release means to allow a user to manually release the grip on the tube so that it can be removed from the coupling. This is advantageous as it makes the coupling easier to service and clean and increases the flexibility of the pneumatic system as a whole. Usually, the release means comprises a tubular member having one end attached to the grab ring or collet and the other end extending from the body. To release the tube, the release member is manually pushed into the coupling body, which urges the grab ring out of gripping contact with the¹ inserted tube and therefore allows it to be removed. To ensure that the coupling operates smoothly and reliably it is preferable that moisture and dust is prevented from entering the coupling. It is particularly important to prevent dust and moisture from interfering with the operation of the grab ring or collet and the seal, as this will affect the integrity of the coupling. Thus, it is common for pneumatic couplings to include a dust cap. The dust cap comprises a tubular sleeve that fits around the body and has an annular cover portion that partially covers the tube-insertion end of the body of the coupling. The internal diameter of the annular cover portion is such that it covers the release means, and therefore partially shields the grab ring and seal, while allowing a tube to be inserted into the coupling. Thus, the dust cap helps prevent dust, dirt and moisture hindering the movement of the grab ring or collet in the body, to ensure a secure connection, and also ensures that the O-ring seals against the tube and body effectively.

In certain applications it is desirable that the release means for the coupling cannot be operated manually. This is of particular importance in pneumatic braking systems for vehicles, where it would be hazardous if the pneumatic couplings were tampered with.

According to the invention we provide a cap for a tube coupling, the coupling comprising a body having a terminal portion for receiving a tube, sealing means for sealingly engaging the external surface of the tube, tube gripping means for gripping the external surface of the tube to retain it in the body, and release means that extends from the terminal portion of the coupling and which, upon actuation, acts on the gripping means to enable the removal of a tube from the coupling, wherein the cap comprises a mounting portion for mounting it to the body and a cover portion that partially covers the terminal portion of the coupling and abuts the release means, the cover portion being resiliently flexible such that application of a force to the cap causes it to deform. This is advantageous as the cap can be constructed to be sufficiently resilient to reliably shield the gripping means and sealing means, while being sufficiently flexible such that a user can only exert a small manual force upon the release means. The cap of the invention does not provide a suitably rigid surface for a sufficient manual force to be applied to operate the release means, which ensures that the coupling is significantly less prone to tampering. However, a special tool can be used to apply a release force, through the cover portion.

Preferably, the mounting portion is resilient. It is preferable that the cap is formed as a single piece thereby comprising a resilient mounting portion and a flexible cover portion. It will be appreciated that the junction of flexibilities between the resilient mounting portion and the flexible cover portion may be abrupt, or alternatively there could be a gradual increase in flexibility from the mounting portion to the cover portion.

Preferably, the mounting portion of the cap engages with the external surface of the body. The mounting portion of the cap may be an annular sleeve that is an interference fit with the outside surface of the body. The cover portion is preferably annular to enable a tube to be inserted through it into the terminal end of the coupling. Most preferably the cap includes a ledge formed by a reduction in the diameter of the sleeve adjacent the cover portion. The ledge is positioned such that it abuts the terminal end when the cap is mounted on the body thereby ensuring that the cover portion is appropriately positioned to prevent the ingress of moisture and dust.

The mounting portion of the cap and the external surface of the body may have engagement means securely affix the cap to the coupling. Preferably the engagement means comprises a ridge that engages within a groove. Preferably the ridge is annular and forms part of the internal surface of the mounting portion, and the groove is annular and formed in the external surface of the body. The ridge may have a snap engagement in the groove, so that it clicks into place.

Preferably, the inwardly facing edge of the cover portion is adapted to engage with an inserted tube. Most preferably, the inwardly facing edge of the cover portion is tapered such that it narrows in the tube insertion direction. This ensures that a reliable engagement is formed when the tube is inserted and resiliently deforms the cover portion in the tube insertion direction.

The release means may form part of the gripping means. Preferably, the release means and the gripping means are in the form of a collet. Alternatively, the gripping means may be a grab ring.

There now follows by way of example only a detailed description of the present invention with reference to the accompanying drawings in which;

Figure 1 is a section through a pneumatic tube coupling;

Figure 2 is a cap according the invention; and

Figure 3 shows the coupling of Figure 1 having the cap of the invention mounted thereto.

The tube coupling device 1 shown in the drawings is of the releasable push-in type, and is intended for use in pneumatic systems, to connect a tube to one or more other tubes, or adaptors. The device 1 comprises a body 2 adapted to receive a tube 3 (see Figure 3) , sealing means 4 for sealingly engaging the external surface of the tube 3, and tube gripping means 5 for gripping the external surface of the tube 3 to retain it in the body 2. The device 1 also has a stepped tube support member 6 which co-operates with the body 2 to provide an audible tube insertion indicator 7. The body 2 is itself sealingly mounted by means (not shown) in a port of a connector 8, enabling the tube 3 to be connected to other tubes or adaptors of the pneumatic system.

The body 2 is of plastics material and of annular construction, with a stepped internal bore 9 and a stepped external surface 10. The internal bore 9 has a larger diameter portion 11 at its outer end, in which the gripping means 5 and sealing means 4 are received, and a portion 12 of smaller diameter at its inner end in which the inner end of the support member 6 is received, and which is also adapted to receive the end of the tube 3 in use.

The gripping means 5 comprises a collet member 13 having a tubular member portion 35 with an enlarged inner end 14. The tubular member portion 35 forms the release means and extends from the bore 9. At its inner end the tube has slits 15, and has triangular projections 16 extending radially inwardly to form gripping teeth. A conical surface 17 is provided externally on the enlarged end 14. The collet member 13 is retained in the body 2 by an annular plug 18 fixed in the outer end of the bore 9. The collet member 13 is adapted to slide axially in the plug 18, which has a conical internal surface 19 which engages the conical surface 17 of the collet member 13 to urge the gripping teeth radially inwardly to grip the tube 3 in use. In the position shown in Figure 1 the teeth do not exert a great deal of force, and the collet member 13 can be moved inwardly to allow the tube 3 to be removed. Thus, a user can move the collet member 13, and therefore allow the tube 3 (shown in Figure 3) to be removed, by applying a force to the part of the release means 35 that extends from the bore 9. In order to apply sufficient force to the release means 35 a tool is required (not shown) .

The sealing means 4 comprises a lip seal 20 mounted at the shoulder 21 between the diameter portions 11 , 12 of the bore 9. The seal 20 has an external sealing surface 22 to seal against the bore 9, and an internal lip 23 to seal against the tube 3 in use. In the position shown in Figure 1 , there is an axial clearance between the collet member 13 and the seal 20. The seal 20 may be an O-ring instead.

The tube support member 6 is of plastics material, and is of stepped cylindrical outline. A longer outer end portion 24 is of smaller diameter to fit into the tube 3, while a shorter inner end portion 25 is of larger diameter to slide in the bore portion 12. A shoulder 26 between the portions 24, 25 forms a stop for the end of the tube 3.

Figure 2 shows a cap 40 for reducing the ingress of moisture, dust and dirt into the tube coupling device 1. The cap 40 comprises a mounting portion 41 in the form of an annular sleeve and an annular cover portion 42, which defines a tube-insertion aperture 43. The mounting portion 41 is of a resilient material and is adapted to form an interference fit with the external surface 44 of the body 2. To ensure a secure connection between the cap 40 and the body 2, engagement means 45 are provided. The engagement means comprises an annular ridge 46 on the inside surface of the mounting portion 41 and a complementary annular groove 47 on the external surface of the body 2. When the cap 40 is mounted on the body 2 (as shown in Figure 3) , the ridge 46 of the resilient mounting portion 41 snaps into engagement with the groove 47 on the body 2. Adjacent the cover portion 42, the mounting portion 41 decreases in diameter, thereby forming a ledge 48. The ledge 48 is adapted to abut the body 2 when the engagement means 45 is interengaged.

The cover portion 42 is of a flexible material. An inwardly facing edge 49 of the cover portion 42 is tapered such that it narrows in the tube insertion direction. This ensures that an effective seal is formed when the tube 3 is inserted and resiliency deforms the cover portion 42 in the tube insertion direction (as shown in Figure 3) . The cover portion 42, adjacent the inwardly facing edge 49, is adapted to abut a terminal end 50 of the release means 35. As the cover portion 42 is flexible, manual application of a force to it (when mounted on the body 2, as shown in Figure 3) is insufficient to move the release means 35 and release the tube 3. A special tool (not shown) can however be used to move the release means 35, applying the force through the cover portion 42. Thus, the tube coupling device 1 is resistant to tampering.

Figure 1 shows the coupling device 1 before insertion of a tube 3, with the tube support member 6 in a retracted position. On insertion of a tube 3, its end is fitted over the outer end portion 24 of the tube support member 6, and within the collet tube. As the tube is pushed in, it moves along the tube support member, past the collet teeth 16 and the seal 20, moving the lip 23 radially outwardly (as shown in dashed lines in Figure 3) , until it reaches the stop 26.

When the system is pressurised the tube 3 may move outwardly again. It takes with it the collet member 13, causing the teeth 16 to grip more tightly to prevent its removal.

Claims

1. A cap for a tube coupling, the coupling comprising a body (2) having a terminal portion for receiving a tube (3) , sealing means (4) for sealingly engaging the external surface of the tube (3) , tube gripping means (5) for gripping the external surface of the tube (3) to retain it in the body (2) , and release means (35) that extends from the terminal portion of the coupling (1) and which, upon actuation, acts on the gripping means (5) to enable the removal of a tube (3) from the coupling, wherein the cap (40) comprises a mounting portion (41) for mounting it to the body (2) and a cover portion (42) that partially covers the terminal portion of the coupling and abuts the release means (35) , the cover portion (42) being resiliently flexible such that application of a force to the cap (40) causes it to deform.

2. A cap for a tube coupling according to claim 1 , in which the mounting portion (41) is resilient.

3. A cap for a tube coupling according to claim 1 or claim 2, in which the cap (40) is formed as a single piece comprising a resilient mounting portion (41) and a flexible cover portion (42) .

4. A cap for a tube coupling according to claim 3, in which the junction of flexibilities between the resilient mounting portion (41) and the flexible cover portion (42) is abrupt.

5. A cap for a tube coupling according to claim 3, in which in which there is a gradual increase in flexibility from the mounting portion (41) to the cover portion (42) .

6. A cap for a tube coupling according to any preceding claim, in which the mounting portion (41) of the cap (40) engages with the external surface of the body (2) .

7. A cap for a tube coupling according to any preceding claim, in which the mounting portion (41) of the cap (40) is an annular sleeve that is an interference fit with the outside surface of the body (2) .

8. A cap for a tube coupling according to any preceding claim, in which the cover portion (42) is annular to enable a tube (3) to be inserted through it into the terminal end of the coupling (1) .

9. A cap for a tube coupling according to claim 7 or claim 8, in which the cap (40) includes a ledge (48) formed by a reduction in the diameter of the sleeve (41) adjacent the cover portion (42) .

10. A cap for a tube coupling according to claim 9, in which the ledge (48) is positioned such that it abuts the terminal end when the cap (40) is mounted on the body (2) .

11. A cap for a tube coupling according to any preceding claim, in which the mounting portion (41) of the cap (40) and the external surface of the body (2) have engagement means (45) to securely affix the cap (40) to the coupling.

12. A cap for a tube coupling according to any preceding claim, in which the engagement means (45) comprises a ridge (46) that engages within a groove (47) .

13. A cap for a tube coupling according to claim 12, in which the ridge (46) is annular and forms part of the internal surface of the mounting portion (41) , and the groove (47) is annular and formed in the external surface of the body.

14. A cap for a tube coupling according to claim 12 or claim 13, in which the ridge (46) has a snap engagement in the groove (47) , so that it clicks into place.

15. A cap for a tube coupling according to any preceding claim, in which an inwardly facing edge (49) of the cover portion (42) is adapted to engage with an inserted tube (3) .

16. A cap for a tube coupling according to claim 15, in which the inwardly facing edge (49) of the cover portion (42) is tapered such that it narrows in the tube insertion direction.

17. A cap for a tube coupling according to any preceding claim, in which the release means (35) forms part of the gripping means (5) .

18. A cap for a tube coupling according to any preceding claim, in which the release means (35) and the gripping means (5) are in the form of a collet (13) .

19. A cap for a tube coupling according to any of claims 1 to 16, in which the gripping means (5) is a grab ring.