GB2226861A

GB2226861A - Connecting pipes and clusters comprising such pipes with push-fit connectors

Info

Publication number: GB2226861A
Application number: GB8928384A
Authority: GB
Inventors: Daniel Belisaire
Original assignee: Legris SA
Current assignee: Legris SA
Priority date: 1988-12-16
Filing date: 1989-12-15
Publication date: 1990-07-11
Also published as: GB8928384D0; IT8968107A0; IT1237695B; ES2018996A6; FR2640723B1; JPH02209690A; DE3941236A1; FR2640723A1

Abstract

A connecting pipe, preferably of plastics material, comprises a tube (2) of which at least one end is joined hermetically to an end piece (3) containing an instantaneous connection device intended to receive a tubular inlet or outlet (14) of an element which is to be connected. The tube (2) is advantageously semi-rigid and preshaped. The invention also relates to clusters obtained by assembling a plurality of such pipes. Motor vehicle construction is a sphere of application of these connecting pipes, since they are very reliable and assembled very rapidly. <IMAGE>

Description

CONNECTING PIPES AND CLUSTERS COMPRISING SUCH PIPES The present invention relates to connecting pipes used in circuits for fluids and to clusters formed by assembling these pipes. It relates more specifically to pipes of plastics materials.

As a rule, to connect the ends of a pipe or conduit to elements ofoa circuit to be connected, use is made of several components which have to be assembled. In the automotive field, for example within the fuel supply circuit, the connection of the two ends of the pipe joining the tank to the pump is made by insertion of fluted end pieces into these ends and by joining the end pieces to the tank outlet and the pump inlet, respectively, by means of hoses tightened with clips. Another and more recent technique consists in using instantaneous connection devices: use is then made of double joints of which the two opposed orifices (inlet and outlet) each comprise an instantaneous connection device. The cylindrical end piece of an element to be connected is engaged in one of the orifices whereas the other orifice receives a pipe end.

Four connection points and the same number of instantaneous connection devices are thus used for connection of two elements, for example a tank and a pump. In any case, the multiplicity of connecting elements and connection points necessitates substantial assembly times and considerable risks of breakdown (poor tube attachment, leaks). Furthermore, the fluid passage commonly has several successive restrictions at the points of connection.

To secure these objects, a pipe according to the invention comprises a tube of which at least one end is joined in a secure and leakproof manner to an end piece containing an instantaneous connection device intended to receive the tubular inlet or outlet of elements to be connected.

In this way, to connect two elements such as a tank and a pump, for example, via a pipe according to the invention which is provided with an end piece at each extremity, no more than two instantaneous connection devices will be needed for the two points of connection, instead of four.

On the other hand, the fact that all the functional elements are in one piece instead of at least three, will be a substantial advantage, in particular from the point of view of storage and assembly.

The joint between the tube and the end piece of the pipe is preferably established by bonding or welding. In a preferred embodiment of the invention, the said end piece has a bore to receive the end of the tube and a secure and leakproof interconnection is obtained, by bonding or welding, between the surfaces in mutual contact.

According to another aspect of the invention, a method for producing the sealed joint between a pipe and an end piece of plastics material comprises the steps of incorporating in this latter a seat or housing to receive the tube end, which narrows towards the inside, inserting the tube pipe end into the said seat or socket effecting a relative rotational displacement between the tube and the end piece, whilst causing the tube to advance into the constricted portion of the said socket, in such a way as to cause heating by friction and fusion of the material at the surfaces in mutual contact of the tube and of the end piece, and then immobilising the assembly in such a manner as to obtain the welding of the tube in the end piece.

A preferred embodiment of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a plan view of a pipe according to the invention; Figure 2 is a view in axial cross-section of one of the ends of the pipe of Figure 1; Figures 3 and 4 are views in partial cross-section illustrating modified embodiments of the joint between the end of a tube and an end piece in a pipe according to the invention; Figure 5 is a plan view of a cluster obtained by assembling a plurality of pipes according to the invention; Figure 6 is a view in axial cross-section of a pipe end comprising an instantaneous and indetachable connection device; Figure 7 is a view in axial cross-section of a pipe end comprising an instantaneous connection device detachable by means of a screwdriver in the manner illustrated in Figure 8;; Figure 9 is a view in axial cross-section of a pipe extremity comprising another instantaneous connection device detachable by means of a special tool shown in end and side views in Figures 10 and 11; and Figure 12 is a plan view of a pipe end comprising an end piece in the form of a right angle bend.

In the following description identical elements bear the same references in all the drawings.

The pipe 1 illustrated in Figure 1 comprises a tube 2 and, at each end of the tube 2, an end piece 3. The end apiece 3 contains an instantaneous connection device, typically of the type described in FR-A-2,012,796 in the name of the present applicant. The tube 2 will advantageously be made of a semi-rigid plastics material, in which case it will be preshaped according to the intended use of the pipe 1. If appropriate, one end only of the pipe may comprise an end piece such as 3.

In Figure 2, the end piece 3 illustrated is an instantaneous connector for liquids. Its casing 4 of plastics material is of cylindroconic form and comprises a bore of reduced diameter 5, three bores 6,7,8 with respective diameters which increase successively towards the outlet opening at the right hand end of the Figure and then, to the left of the bore 5, a bore into which the tube 2 fits.

Two sealing rings 9 and 10 separated by a washer 11 are housed in the bore 7.

In the bore 8 is secured a sleeve 12 wherein is slidably fitted a flexible annular gripper having several teeth 13. Within its bore, the sleeve 12 has a divergent section for tightening the teeth of the gripper on to a tube 14 engaged in the end piece and illustrated by fine dashdotted lines in Figure 2.

At its inner extremity, the sleeve 12 has an inwardly directed annular flange 15 which, opposite to the bottom of the bore 7, axially delimits the seat of the sealing rings 9 and 10, to hold these latter virtually free of movement.

Longitudinal pulsations on the sealing rings 9 and 10, which would be liable to cause the formation of a film of liquid and consequently leakages between the inner diameter of the rings 9 and 10 and the outer surface of the tube 14, are thus prevented.

Although two sealing rings are provided in the end piece 3 shown in Figure 2, it is also possible to use a single ring the depth of the bore 7 being commensurately reduced.

To establish the connection between the pipe 1 and the tube 14, it is sufficient to insert the latter in the end piece 3 until it strikes the bottom of the bore 6 and then to apply a pull between the end piece and the tube 14, so as to tighten the gripper 13 on the wall of the tube 14.

The tube 2 entering the end piece 3 is joined hermetically to it by welding between their surfaces in mutual contact. A particularly advantageous method of making this joint consist in causing the heating and fusion of the plastics material at mutually contacting surfaces of the tube 2 and of the end piece 3 by friction, by effecting a relative rotational movement between the two elements.

To this end and as shown in Figure 2, the bore receiving the tube 2 in the end piece 3 has an entrance of a diameter very little greater than the external diameter of the tube 2, followed by a section of decreasing diameter. To effect the welding after engendering the relative rotary displacement between the tube 2 and the end piece 3, the tube 2 is caused to advance into the bore in step with the fusion of the material on the surfaces in mutual contact. This advance is stopped a little before the tube 2 impinges against the bottom of the bore, in such a way as to provide an adequate space for the flow of the material and thereby to prevent flows towards the inside.

In this embodiment, the bore 5 of the end piece 3 has a diameter substantially equal to the internal diameter of the tubes 2 and 14, so that the fluid passing through does not encounter any restriction.

In the embodiment of Figure 3, in the bore for receiving of the tube 2, which bore is of the same general shape as that of Figure 2, an annular flange projects axially from the bottom of the bore in such a way as to form an annular groove 17 of substantially V-shaped cross-section to receive the tube 2. This embodiment allows a greater welded surface area to be established between the two elements, and thereby an improved joint. On the other hand the annular flange 16 slightly restricts the fluid passage.

In Figure 4, the base part 18 of the groove 17 formed by the flange 16 in the bore for reception of the tube 2 has a re-entrant section which provides additional space for the flow of the material and consequently allows the tube 2 to be inserted more deeply into the groove and to obtain an improved assembly. As in the preceding case, the flange 16 slightly restricts the fluid passage.

In practice, pipes according to the invention may be assembled into a cluster such as is shown in Figure 5. The pipes 1 of the cluster comprise a straight centre portion along which they are joined to one another by means of diagrammatically illustrated securing stays or the like 19.

On each side, of the portion la, the parts lb and lc of the pipes are preshaped as a function of the circuits in which the cluster is to be integrated. In a motor vehicle, a cluster of this type may be used to connect the front and rear elements of a plurality of circuits; fuel circuit, braking circuit, window washer circuit, etc. For some specific applications, composite clusters comprising pipes according to the invention and conventional pipes may also be used.

The end piece 3 illustrated in Figure 6 contains an instantaneous connection device.of the type described in the foregoing, which has the feature of providing a permanent joint with a tube 14. For this purpose, the gripper 13 is situated entirely within the sleeve 12, which at its outer end has an annular flange 20 defining an opening having a diameter very close to the internal diameter of the gripper 13 and to the outer diameter of the tube 14. As a result, when this latter is inserted into the end piece, the gripper 13 is wholly enclosed and consequently inaccessible so that it is impossible to displace the same and by virtue of this fact, impossible to free the teeth from the tube 14.

In contrast, the end piece 3 in Figure 7 allows a joint to be made which may be freed by means of a screwdriver. A collar 21 of internal diameter substantially equal to that of the gripper is integrally connected to the sleeve 2 via two opposed jaws 22. On the other hand, the outer end of the gripper 13 extends beyond that of the sleeve 12. It is apparent from Figure 8 that to loosen the gripper 13 to release the tube 14 it is sufficient to apply the tip of a screwdriver to its outer end between the jaws 22 and to use it as a lever whilst bearing against the collar 21.

In Figure 9, the gripper 13 is positioned completely inside the sleeve 12. The end of the gripper 13 forms an outer flange 23 the external diameter of which corresponds to the aperture diameter of the sleeve 12. It is consequently possible to act on the gripper 13 to free it when a tube 14 is inserted into the end piece. A special tool 24 used for this operation is shown in Figures 10 and 11. It is formed essentially by a flat half-collar 25 welded along one of its sides to the rim of an excision having a semicircular base in a disc-shaped plate 26. The collar 25 has an internal diameter slightly greater than the outer diameter of the tube 14 and an external diameter slightly smaller than the entry diameter of the sleeve 12. To loosen the gripper 13, the tool 24 is placed astride the tube 14, the collar 25 being directed towards the inlet of the sleeve 12, after which a push towards the inside of the end piece is exerted on the plate 26, the collar 25 then acting on the flange 23.

In particular applications, it may be of interest to provide an end piece 3' in the form of a bend on a pipe end. An end piece of this type generally comprises, as shown in Figure 12, by an outer portion 27 containing the instantaneous connection device and another portion 28 which is secured to the portion 27 by detent means. In this case, a welded joint of the type described in the foregoing and illustrated in Figures 2 to 4 is made between the tube 2 of the pipe and the orifice of the portion 28 then being engaged with the portion 27 by detent means.

Claims

1. Connecting pipe for connection of the elements of a circuit for fluids, which comprises a tube and, at one extremity at least of the tube, an end piece which contains an instantaneous connection device intended to receive an inlet or outlet in the form of a tube, of an element to be connected.

2. Connecting pipe according to claim 1, wherein a leakproof and indetachable joint between the tube and the or each end piece is obtained by welding or bonding.

3. Connecting pipe according to claim 2, wherein the joint between the tube and the or each end piece is produced by inserting one end of the tube into a matching bore of the end piece, the welding or bonding being effected between the mutually contacting surfaces of the tube and of the end piece.

4. Connecting pipe according to claim 1, wherein the tube and the end pieces are of plastics material and the joint between the tube and the end piece is obtained by providing the end piece with a bore to receive the tube, which bore narrows towards the inside, effecting a relative rotational movement between the tube and the end piece whilst causing the tube to advance into the constricted portion of the said bore, in such a way as to cause the heating by friction, and fusion, of the material at the mutually contacting surfaces of the tube and of the end piece and then in immobilising the whole in such a way as to secure the welding of the tube into the end piece.

5. Connecting pipe according to any preceding claim wherein the tube is preshaped.

6. Connecting pipe according to any preceding claim wherein the end piece is intended for application in a circuit for liquids and the sealing joint or joints of its instantaneous connection device are immobilised longitudinally in their respective seals to prevent any leakage of liquid between the internal diameter of the joints and the outer surface of the tube to be connected.

7. Connecting pipe according to any preceding claim which comprises at least one instantaneous connection device providing a non-detachable joint.

8. Connecting pipe according to any preceding claim which comprises at least one instantaneous connection device provided with means for opening the joint it provides with the aid of a screwdriver or the like.

9. Connecting pipe according to any one of claims 1 to 6, which comprises at least one instantaneous connection device which allows the joint it provides to be opened by means of a special tool.

10. Connecting pipe according to one of claims 1 to 9, which comprises at least one end piece in the form of a right-angled bend.

11. A cluster of pipes, which includes at least one pipe according to any preceding claim.

12. Cluster of pipes according to claim 11, whose component pipes comprise straight intermediate portions interconnected by means of securing stays.

13. A connecting pipe substantially as herein described with reference to Figures 1 and 2, Figure 3, Figure 4, Figure 6, Figures 7 and 8, or Figures 9 to 11 of the accompanying drawings.

14. A cluster of pipes according to claim 11, substantially as herein described with reference to Figure 5 of the accompanying drawings.