GB2214228A

GB2214228A - Pipe clamp

Info

Publication number: GB2214228A
Application number: GB8901222A
Authority: GB
Inventors: Jack Ingham
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-01-22
Filing date: 1989-01-20
Publication date: 1989-08-31
Also published as: GB8801386D0; GB8901222D0

Abstract

A pipe clamp which comprises a resilient portion coiled to present at least one turn of a helix 22 and adapted to fit over a pipe to be clamped, together with means for reducing the diameter of the helix. The latter may be a bracket 28 over the free ends of the helix brought into engagement with a turn 30 of the helix by means of nuts 26. The clamp provides even pressure and a gas-tight seal without causing distortion of the pipe. <IMAGE>

Description

PIPE CLAMP This invention relates to a pipe clamp and in particular relates to pipe clamps for use in connection with motor vehicle exhaust systems and the like.

The pipes forming a motor vehicle exhaust system often require to be joined together. To this end, one end section of one the two lengths of pipe to be joined is made slightly oversize and is longitudinally split. The oversize split end fits over the end of the other pipe and is clamped thereto usually by means of a conventional "Ubolt" such as is illustrated in figure 1 of the attached drawings.

The latter suffers from various disadvantages, one of the most important being the pressure is not applied to the pipe evenly since the sides of the U-bolt apply virtually no pressure, and thus a gas tight seal is very difficult to achieve.

The invention seeks to provide a form of pipe clamp improved in the above respects.

Accordng to the present invention there is provided a pipe clamp which comprises a resilient portion coiled to present at least one turn of a helix and adapted to fit over a pipe to be clamped, together with means for reducing the diameter of the helix.

The clamp of the invention completely circumscribes the pipe and applies pressure substantially evenly around its circumference Thus the clamping action may more easily be made gas tight. Furthermore distortion of the pipe, which commonly occurs with U-bolts, may be avoided.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic view of a conventional U bolt; Figure 2 is a perspective view of a pipe clamp in accordance with the invention; Figures 3a to 3c are respectively front and side elevations and a plan view corresponding to figure 2; Figures 4a to 4c are respectively front and side elevations of a second embodiment of the invention, and a further front elevation of the clamp in the tightened configuration; and Figures Sa to 5c are similar view to Figure 4 of a third embodiment.

Referring to the drawings, the conventional U-bolt illustrated in figure 1 has a U-section portion 10 adapted to receive a pipe 12 to be clamped. This comprises fee ends 14 and a bight 18. The free ends of the U-section 14 are threaded to receive nuts 16. A clamping bracket 20 is carried on the free ends below the nuts and is forced -downwardly in the direction of arrow A to contact the pipe 12 by tightening of the nuts 16. It will be appreciated that the pressure on the pipe is exerted between the bracket 20 and the bight 18 of the U-section 10 with very little pressure being exerted by the sides of the U section.

Referring now to figures 2 and 3, a pipe clamp in accordance with the invention is illustrated. This consists of a helical portion 22 of a resilient material forming at least one complete turn of a helix. As illustrated, this embodiment has almost two complete turns.

The free ends 24 of the portion 22 are threaded as before and receive nuts 26. A bracket 28 fits over the free ends 22 and is drawn downwardly until it contacts the upper portion 30 of one turn of the helix. Further tightening of the nuts 26 causes the helix to reduce its size thus applying substantially even pressure around the circumference of a pipe held within the portion 22.

The material from which the resilient portion 22 is made may be a similar material to that used in conventional U-bolts, namely round section mild steel. This is sufficiently resilient to enable the helix to be reduced in size to clamp a pipe while returning to its original size when the nuts 26 are released to allow the pipe to be unclamped. Other materials may be used and it is envisaged that in certain circumstances that the material, rather than being resilient, may in fact be flexible, for example a chain provided with threaded end portions 24 to enable it to be drawn tightly around a pipe to clamp the same and subsequently be released when desired.

Turning now to Figure 4, and using like numerals for like parts, the clamp illustrated is essentially the same as that of Figures 2 & 3 except that the nut 26 are replaced by a bolt 30. The free ends 24 of the helix are welded or otherwise attached to a cross-bar 32 having a threaded hole therein for receiving the bolt 30. Figure 4a shows the bolt in its raised or loosened position in which the helix 22 may have an internal diameter of, say, 44 mm.

On tightening the bolt 30 it bears on the bracket 28 and reduces the diameter of the helix as before, to approximately 40 mm. This embodiment, requiring the manipulation of a single bolt head, is ideally suited to manual operation without the use of tools such as a spanner e.g. by the provision of a wing nut rather than a bolt head.

Figure 4 illustrates a further embodiment in which a single turn of helix 22 is employed. The free ends 24 have attached thereto. e.g. by welding, a nut 34 and a stop 36.

A bolt 38 passes through the nut 34 and engages the stop 36. On tightening the bolt 38, the stop 36 and nut 34 are pushed apart, reducing the diameter of the helix as shown in Figure 5c. The embodiment is simple and uses very little material. The action of pushing the helix ends apart has been found to be better than drawing them together since it results in a more even clamping action around the entire circumference of the helix. The stop 36 preferably is provided with an indentation or recess to receive the end of the bolt 38 and help prevent it slipping off the stop.

The clamp of the invention provides a simple and extremely effective means of forming a gas-tight seal in in clamping applications of all kinds, but in particular with exhaust systems of motor vehicles.

Claims

1. A pipe clamp which comprises a resilient portion coiled to present at least one turn of a helix and adapted to fit over a pipe to be clamped, together with means for reducing the diameter of the helix.

2. A clamp as claimed in claim 1 in which the helix presents substantially two turns.

3. A clamp as claimed in claim 2 in which the means for reducing the diameter of the helix comprises a bracket located on the free ends of the resilient portion bearing against a turn of the helix.

4. A clamp as claimed in claim 3 in which the bracket is is moved by the action of nuts mounted on threaded portions of the free ends.

5. A clamp as claimed in claim 2 in which the free ends terminate in a cross-bar through which a bolt acts against a turn of the helix.

6. A clamp as claimed in claim 5 in which the bolt is provided with a wing nut for manual operation.

7. A clamp as claimed in claim 1 in which a single turn of helix is provided and the means for reducing the diameter of the helix comprises a bolt arranged to force apart the free ends of the helix.

8. A clamp as claimed in any of claims 1 to 7 in which a flexible material is employed rather than a resilient material.

9. A clamp as claimed in claim 8 in which the flexible material is a metal chain or braid.

10. A pipe clamp substantially as hereinbefore described and as illustrated in Figure 2 to 5 of the accompanying drawings.