Pipe joints or couplings – With assembly means or feature – Particular tool-engaging means or with tool
Patent
1996-03-04
1998-06-23
Melius, Terry Lee
Pipe joints or couplings
With assembly means or feature
Particular tool-engaging means or with tool
285308, 285323, 285912, F16L 5500
Patent
active
057694621
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to couplings in which a hollow body is adapted to grip and retain an object inserted into it, with the gripping effect being releasable such that the object may be removed from the body.
In particular, the invention relates to devices in which the attempted removal of the object from the body without operating a release mechanism causes a gripping device to engage and grip the object more tightly, so that removal of the object is prevented.
2. Description of the Prior Art
An example of such a releasable coupling has a resilient washer having a plurality of resilient fingers located near the entrance to the body. The resilient fingers extend into the hollow body in a direction away from the entrance and are oriented at an acute angle to the body's internal surface, so that a tube may be inserted by pushing it past the fingers, but removal of the tube is prevented by the gripping effect of the fingers as they are forced to bend outwards. The tube may be removed by pressing a ring, for example, which acts on the washer to bend the fingers away from the tube surface, thus releasing their grip on the tube and allowing its removal.
Such prior art devices using a washer with internally facing resilient fingers have been found to have a number of problems. Firstly, they rely on the resilience of the fingers to provide sufficient initial grip on the inserted tube so that the withdrawal of the tube is prevented by the effect of pulling the tube from the socket tending to bend the fingers towards the tube. Repeated use of the device will tend to reduce the resilience of the fingers, therefore weakening the gripping effect on the tube and thus degrading the coupling's operation. If the angle of the fingers to the axis of the tube when gripping it becomes too close to the perpendicular, it may be possible to remove the tube by applying sufficient force since the fingers can more easily be bent in this position. Once this has occurred, the device may be permanently damaged. There is also a risk that because the tube must be forced past the resilient fingers as it is inserted, it or the fingers may become damaged. This can be particularly important if a good seal between the tube surface and coupling is required. Finally, since it is necessary to bend the fingers away from the tube surface in order to release the tube, there is also a requirement that the inserted tube must be able to be moved at least a very small distance further into the socket in order to lessen the gripping of the tube by the fingers so that this can be achieved. Thus if the tube has been inserted into the body as far as possible, there may not be sufficient axial play for the tube to be releasable.
Another prior art device, which does not use a washer having resilient fingers, thus overcoming some of the problems mentioned above, is described in GB-1520742. This document discloses a tube coupling having a cylindrical hollow body in which a collet may be inserted from the end in which the tube is to be inserted. The collet has inwardly tapering resilient arms which extend into the body away from the opening through which the tube is inserted. The collet is free to move axially within the body, and a cam surface is provided on the body near the entrance and is arranged such that attempted removal of the collet past this surface forces the resilient arms inwards towards the centre of the body. Thus, when a tube is inserted, this forces the resilient arms of the collet apart, but attempted removal of the tube brings the arms into contact with the cam surface, causing them to grip the tube more tightly. The arms grip the tube due to their resilience and are thus carried with it. By pushing the end of the collet which protrudes from the entrance of the body towards the body, the resilient arms are prevented from coming into contact with the cam surface, and are free to spread slightly, and thus the tube can be removed.
An improved version of the GB-1520742 device is desc
REFERENCES:
patent: 1930194 (1933-10-01), Dillon
patent: 2108040 (1938-02-01), Bluehdorn et al.
patent: 5328215 (1994-07-01), Grenier
Melius Terry Lee
Shackelford Heather
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