GB2245671A

GB2245671A - A pipe coupling with frictional engagement to lift collet teeth clear of pipe during insertion

Info

Publication number: GB2245671A
Application number: GB9015040A
Authority: GB
Inventors: Ronald Pardy
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1990-07-07
Filing date: 1990-07-07
Publication date: 1992-01-08
Anticipated expiration: 2010-07-07
Also published as: GB2245671B; GB9015040D0

Abstract

A push-in pipe coupling has teeth 28 on a collet 22 which grip the pipe 10 to prevent withdrawal. A friction grip is established on the pipe surface which forces the collet 22 into the coupling as the insertion action takes place, and this movement of the collet lifts the retention teeth 28 out of the path of movement of the pipe to prevent damage to the surface of the pipe. Once the pipe is inserted, withdrawal of the pipe is prevented in the conventional manner. <IMAGE>

Description

A PIPE COUPLING This invention relates to a pipe coupling of the type where one pipe end is pushed into a socket and where the action of pushing the pipe end into the socket both forms a seal and retains the pipe end in the socket.

A pipe coupling of this type is described for example in GB-PS 1 520 742. Couplings of this type find application for example in the fuel lines of motor vehicles where it is desirable to be able to complete a pipe joint with a simple push-in action.

Know couplings of this type accomplish the pipe retention function by having a set of metal teeth which can be pushed aside to allow insertion of the pipe in one direction but which are cammed down onto the pipe surface and bite into the pipe surface if removal is attempted. These teeth are mounted on a collet which is axially moveable to a limited extent so that the parts of the collet which support the teeth can move over a cam surface which either allows the teeth radial outward movement or forces them radially inwardly to bite into the pipe material.

It is a disadvantage of such couplings that the collet teeth are in contact with the pipe surface as the pipe is being inserted. As a result, the outer surface of the tube is marked and this can affect the sealing function of the coupling.

It is an object of the present invention to overcome this disadvantage in this type of coupling.

According to the invention, there is provided a pipe coupling comprising a socket into which a pipe end can be pushed, sealing means in the socket for making a seal with the pipe end, an axially moveable collet with internally extending teeth which yield to allow entry of the pipe but grip the pipe to resist withdrawal, a cam surface on the inside of the socket which cooperates with the collet so that when the collet moves in a direction axially outward of the socket, the teeth are forced radially inwardly, and when the collet moves in a direction inwardly of the socket, the teeth are lifted radially outwardly, and wherein a collar abuts the collet and frictionally engages the pipe outer surface so that as the pipe end is pushed through the collar, the collar exerts an axial force on the collet to push the collet axially inwardly and to lift the teeth to a position where they do not contact the pipe surface during insertion.

The collar can be formed by a series of radially inwardly extending projections at the mouth of the collet, or can be formed by a separate collar which is mounted either on the pipe end or at the entry end of the socket.

The collar will be of a material which is soft relative to the material of the pipe, so that the collar can frictionally grip and slide along the pipe without marking the pipe outer surface.

The collar may be a washer-like component which is fitted onto the pipe end before the pipe end is inserted in the socket.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a section through a first form of coupling in accordance with the invention; Figure 2 shows the coupling of Figure 1 during insertion; Figure 3 is a sectional view of a second form of coupling in accordance with the invention; Figure 4 shows a collar used in the embodiment of Figure 3; and Figure 5 is a cross section through the collet in the embodiment of Figure 1, taken on the lines V-V.

Figure 1 shows a coupling by means of which a pipe end 10 is coupled to a stub pipe 12. The stub pipe 12 will be connected in a known manner to another component or possibly to another pipe. The stub pipe 12 is formed at one end of a socket generally designated 14. The socket comprises a body moulding 16 which contains two sealing 0rings 18 and 20, the diameters of which are such that they will seal against the outer surface of the pipe 10 and against the inner surface of a counterbore in the socket, when the pipe is pushed fully into the socket.

A collet 22 is fitted in the mouth of the body 16. The collet is at one end in the form of a continuous ring 24, and has four axially extending fingers 26 extending into the body. Each of these fingers carries a metal tooth 28 (see Figure 5). The collet itself is axially moveable to a limited extent in the mouth of the body. As the collet moves in an inward direction, the inner ends of the fingers 26 ride up a spreader ring 30 to the position indicated in Figure 2, where the teeth 28 are moved in a radially outward direction. When the collet is moved in the opposite axial direction, a camming action takes place between a retaining ring 32 and the outer face of the collet which forces the end of the fingers and the teeth 28 in a radially inward direction.

Additionally, at the outer end of the collet, a series of inward projections 34 are provided.

When the pipe end 10 is pushed into the socket, it first of all makes frictional contact with the projections 34.

Because the diameter of the circle defined by the inner ends of these projections is slightly smaller than the outer diameter of the pipe 10, friction will be produced between the pipe and the collet. Although the pipe can be pushed in past these projections 34, the act of doing so will produce an axially inward force on the collet which will cause the fingers to be pushed up the spreader ring 30 so that the position shown in Figure 2 is taken up. As a result, the teeth 28 are lifted radially outwardly so that as the pipe 10 is pushed in, the teeth do not make contact with the pipe surface and the pipe can be pushed right in until the outer surface of the pipe is sealed against the O-rings 18,20.The material of the projections 34 will be chosen so that it will not mark the outer surface of the pipe and as a result there will be no danger of the pipe being scratched before it seals against the O-rings 18,20.

If an attempt is made to pull the pipe 10 out, then the collet will initially move in the outward direction with the pipe, and the outer face of the collet teeth will bear against the inner surface of the retaining ring 32. The retaining ring is shaped so that as the collet moves in an outward direction, so the teeth 28 are pushed radially inward and bite into the pipe surface thus preventing withdrawal in the manner already known for connectors of this type.

A pipe joint of this type can be disassembled if desired by holding the collet against radial outward movement whilst the pipe is pulled out, and various components have been proposed for facilitating this task. Disassembly however forms no part of this invention.

In an alternative embodiment, shown in Figure 3, a friction washer 36 (see Figure 4) is mounted on the end of the pipe 10. The washer is a tight fit on the pipe, but can slide along the pipe surface when sufficient force is applied.

The washer is initially fitted on the pipe at a distance a from the pipe end which is less than the distance b between the end of the collet and the teeth 28. When the pipe is inserted into the socket, the washer 36 comes into contact with the outer end of the collet and pushes the collet inwards so that the fingers are spread by the spreader ring 30 before the pipe reaches the location of the teeth 28.

The material of the washer 36 will be chosen so that it does not mark the pipe surface as it slides along the pipe.

The invention thus provides a very simple way of ensuring that the teeth 28 are lifted away from possible contact with the pipe surface during insertion movement. This makes it possible to use this type of connector with a wide range of pipe materials and also allows the joint to be disassembled and reassembled a number of times without the pipe surface becoming damaged.

Claims

1. A pipe coupling comprising a socket into which a pipe

end can be pushed, sealing means in the socket for making a seal with the pipe end, an axially moveable collet with internally extending teeth which yield to allow entry of the pipe but grip the pipe to resist withdrawal, a cam surface on the inside of the socket which cooperates with the collet so that when the collet moves in a direction axially outward of the socket, the teeth are forced radially inwardly, and when the collet moves in a direction inwardly of the socket, the teeth are lifted radially outwardly, and wherein a collar abuts the collet and frictionally engages the pipe outer surface so that as the pipe end is pushed through the collar, the collar exerts an axial force on the collet to push the collet axially inwardly and to lift the teeth to a position where they do not contact the pipe surface during insertion.

2. A pipe coupling as claimed in any preceding claim, wherein the collar is formed by a series of radially inwardly extending projections at the mouth of the collet.

3. A pipe coupling as claimed in Claim 1, wherein the collar is a separate collar which is mounted either on the pipe end or at the entry end of the socket.

4. A pipe coupling as claimed in Claim 3, wherein the collar is a washer-like component which is fitted onto the pipe end before the pipe end is inserted in the socket.

5. A pipe coupling as claimed in any preceding claim, wherein the collar is of a material which is soft relative to the material of the pipe, so that the collar can frictionally grip and slide along the pipe without marking the pipe outer surface.

6. A pipe coupling substantially as herein described with reference to the accompanying drawings.

7. A method of assembling a pipe coupling which has a socket into which a pipe end can be pushed, sealing means in the socket for making a seal with the pipe end, an axially moveable collet with internally extending teeth which yield to allow entry of the pipe but grip the pipe to resist withdrawal, a cam surface on the inside of the socket which cooperates with the collet so that when the collet moves in a direction axially outward of the socket, the teeth are forced radially inwardly, and when the collet moves in a direction inwardly of the socket, the teeth are lifted radially outwardly, wherein the collet is forced radially inwardly of the socket, as the pipe is pushed in, before the pipe surface comes into contact with the collet teeth.