WO1999019955A1

WO1999019955A1 - Flexible protective sleeves

Info

Publication number: WO1999019955A1
Application number: PCT/GB1998/002938
Authority: WO
Inventors: Mark Cook
Original assignee: Federal-Mogul Technology Limited
Priority date: 1997-10-15
Filing date: 1998-09-30
Publication date: 1999-04-22
Also published as: GB2330393A; GB9821263D0; GB2330393B; GB9721987D0

Abstract

A protective sleeve (10) for use in protecting an elongated member comprises a generally tubular wall (12). The wall (12) defines circumferentially-extending convolutions (15) to increase the flexibility of the sleeve. The wall has a slit (16) therethrough which extends longitudinally of the sleeve and allows access to the interior of the sleeve. Longitudinally-extending edge portions (18) of said wall (12) which border said slit (16) are free of said convolutions (15).

Description

FLEXIBLE PROTECTIVE SLEEVES

This invention is concerned with flexible protective sleeves for use in protecting elongated members such as wires or pipes, eg in the engine compartment of a vehicle. Such sleeves are used to protect, for example, wires leading to spark plugs, the distributor etc., or fuel pipes.

Flexible protective sleeves are widely used to protect wires and pipes from damage. Such sleeves normally have a wall made from wear-resistant and/or heat-resistant polymeric material, such as nylon, polypropylene or thermoplastic elastomers. One type of flexible protective sleeve comprises a generally tubular wall in the form of sheet plastics material, ie the wall is thin and continuous. Such a wall is normally made by extrusion. Usually, such a sleeve has a longitudinal slit through its wall. The slit extends longitudinally of the sleeve and allows access to the interior thereof to enable the sleeve to be installed over a pipe or wire which is already in situ. The wall of such a sleeve normally defines circumferentially-extending convolutions to increase the flexibility of the sleeve, ie the convolutions make the tube more conformable to bends in the wire or pipe. The convolutions in such a sleeve can take various forms, eg a cross-section taken through the wall longitudinally of the sleeve may have the appearance of a sine wave or a square wave. Bends in the sleeve are accommodated by opening of the convolutions on the outer side of the bend and closing of the convolutions on the inner side of the bend.

In a conventional flexible protective sleeve, the convolutions extend from one edge of the longitudinal slit to the other edge thereof, ie the entire wall of the sleeve is convoluted. Such a sleeve is conventionally made by extruding a smooth-walled tube of plastics material, enclosing the tube in a pair of mould blocks which define an internal surface which is formed into a convoluted shape, blowing or vacuum-forming the tube's wall into contact with the internal surface of the blocks so that the plastics wall becomes convoluted, removing the convoluted tube from the blocks, and longitudinally slitting the tube. Although most sleeves of this type are generally-circular in transverse cross-section, the radius of the sleeve varying between crests and troughs in the convolutions of the wall thereof, it is possible for the sleeve to have other cross-sectional shapes to conform to particular circumstances .

In many cases, conventional flexible protective sleeves give rise to undesirable noise. Such noise may be generated by the edges of the slit rubbing against one another as an engine operates. These edges have a convoluted shape and lie generally in contact with one another so that there are many possible areas at which the edges can rub against each other creating noise, eg a twisting motion of the sleeve may cause considerable rubbing contact between the edges with the result that an undesirable "chattering" noise is created.

A flexible protective sleeve having a convoluted wall is described in EP 0 556 140 B where the wall is wrapped in a strip of sound-insulating material, eg felt, which is adhered to the wall of the sleeve and folded over itself. Where the sleeve has a longitudinal slit, the strip's longitudinal edges are passed through the slit and reduce noise created by rubbing contact at the edges of the strip. The process of applying the strip of material is, however, complex and the strip significantly increases the weight of the sleeve. Furthermore, it may be difficult to conform the strip to the outer surface of the wall of the sleeve, eg in the case of a convoluted sleeve of a square wave form. It is an object of the present invention to provide an improved flexible protective sleeve in which noise produced by rubbing contact of the edges of a longitudinal slit in the sleeve is reduced without the use of an adhered strip.

The invention provides a protective sleeve for use in protecting an elongated member, the sleeve comprising a generally tubular wall, the wall having a slit therethrough which extends longitudinally of the sleeve and allows access to the interior of the sleeve, the wall comprising a central portion which extends longitudinally of the sleeve and is formed into circumferentially-extending convolutions which serve to increase the flexibility of the sleeve, characterised in that the wall also comprises two longitudinally-extending edge portions, each edge portion extending generally circumferentially between said central portion and an edge of the wall which borders said slit, the edge portions of said wall being free of said convolutions.

In a protective sleeve according to the invention, the edge portions of the wall are not convoluted so that they contact one another over a greatly reduced area reducing greatly the possible areas of contact between the edges of the slit and hence the possibilities for generating noise through rubbing contact. A further advantage is found in that the edge portions of the wall being free of convolutions reduces abrasion between these edges and an operators hand, in particular his fingers, when the sleeve is installed over an elongated member. With a conventional sleeve having convoluted edge portions bordering the slit, the edge portions act like a saw and can damage an operator's hands.

The convolutions of a sleeve according to the invention may be in the form of a square-wave or a sine- wave, when viewed in longitudinal cross-section, or in any other form which enables the convolutions to close on the inside of curves of the sleeve and to open on the outside of such curves .

A sleeve according to the invention, preferably, has its wall formed from polymeric material, eg plastics material which is extruded into the form of a sheet, eg as a tube .

In a sleeve according to the invention, said edge portions of said wall each may have the shape of a portion of a hollow cylinder. For example, a portion of the internal surface of the mould blocks used to form the convolutions may be free of convolutions so that, in that portion of the die a smooth-walled section of a hollow cylinder is formed of greater diameter than the tube which is blown in the die. The longitudinal slit is cut through this smooth-walled section. Alternatively, provided that the edge portions are narrow, said edge portions may be planar.

Preferably, said edge portions of said wall are between 1mm and 3mm in width, eg a width of 2mm has been found to be suitable in many cases.

Where the sleeve is generally-circular in transverse cross-section, preferably, said edge portions extend arcuately about the centre of the sleeve at a distance from said centre which is substantially equal to the distance from said centre to crests of said convolutions. This gives an advantage that the mould blocks used for forming the convolutions can be more simply constructed. However, the distance from the centre of the sleeve to the edge portions may be different to that of the crests, eg this distance may be between the distances of the crests and the bottoms of the troughs between the crests from the centre of the sleeve. There now follows a detailed description, to be read with reference to the accompanying drawing, of a flexible protective sleeve which is illustrative of the invention.

The drawing is a perspective view of the illustrative sleeve.

The illustrative sleeve 10 comprises a generally tubular wall 12 made of heat-resistant plastics material, specifically nylon 6. The sleeve 10 is, generally, circular in transverse cross-section. The wall 12 is of substantially constant thickness which is in the range 0.3 to 0.5mm. The wall 12 encloses a space 14 in which an elongated member (not shown) can be enclosed.

A central portion 12a of the wall 12 which extends longitudinally of the sleeve 10 is formed into circumferentially-extending convolutions 15 to increase the flexibility of the sleeve 10. The convolutions 15 extend arcuately about the centre of the sleeve 10 over most of the circumference thereof. The convolutions 15 of the wall 12 are approximately in the form of a square wave (when viewed in longitudinal cross-section) and give the external surface of the wall portion 12a a shape which has crests 15a, trough bottoms 15b, and side surfaces 15c. The crests 15a correspond to trough bottoms on the internal surface of the portion 12a and the trough bottoms 15b correspond to crests on the internal surface. The crests 15a and trough bottoms 15b are in the shape of portions of a cylinder centred on the centre of the sleeve 10, the crests 15a having a greater radius than the trough bottoms 15b. The side surfaces 15c extend radially and circumferentially and join the trough bottoms 15b to the crests 15a.

A longitudinal slit 16 through the wall 12 extends longitudinally of the sleeve 10 for the entire length of the sleeve 10. This slit 16 allows access to the interior of the sleeve 10 so that the sleeve can be positioned over an elongated member by passing the member through the slit 16.

The wall 12 also comprises two longitudinally- extending edge portions 18. Each edge portion 18 also extends generally circumferentially of the sleeve 10 between said convoluted central portion 12a of the wall 12 and an edge 19 of the wall 12 which borders the slit 16. The edge portions 18 are free of the convolutions 15, ie the convolutions 15 extend circumferentially until they reach the edge portions 18 and then stop. The edge portions 18 are 2mm in width, ie they form a strip 2mm wide on each side of the slit 16. Each edge portion 18 has smooth inner and outer surfaces. Specifically, each edge portion 18 has the shape of a portion of a hollow cylinder centred at the centre of the sleeve 10. The edge portions 18 have the same radius as the crests 15a and hence extend arcuately about the centre of the sleeve 10 at a distance from the centre of the sleeve 10 which is equal to the distance from said centre to the crests 15a. Thus, the crests 15a merge into the edge portions 18. The trough bottoms 15b are joined to the edge portions 18 by radially and longitudinally extending portions 20 of the wall 12 at each end of each convolution 15. The wall portions 20 meet the side surfaces 15c at right angles.

The illustrative sleeve 10 is formed by a method which is conventional except that the mould blocks used to form the convolutions 15 have an interruption in the surface which forms the convolutions 15. The interruption extends longitudinally and is 4mm wide. At the interruption, the surface of the mould blocks is smooth and has the same radius as the surfaces of the blocks which form the crests 15a. The longitudinal slit 16 is cut along the centre of the portion of the wall 12 which is formed without convolutions 15. It is found that the illustrative sleeve 10 produces significantly less noise than a conventional sleeve which has its slit bordered by convoluted edge portions and that the sleeve 10 can be installed with less risk of hand damage.

Claims

A protective sleeve (10) for use in protecting an elongated member, the sleeve comprising a generally tubular wall (12) , the wall having a slit (16) therethrough which extends longitudinally of the sleeve and allows access to the interior of the sleeve, the wall (12) comprising a central portion (12a) which extends longitudinally of the sleeve and is formed into circumferentially-extending convolutions (15) which serve to increase the flexibility of the sleeve, characterised in that the wall (12) also comprises two longitudinally-extending edge portions (18) , each edge portion (18) extending generally circumferentially between said central portion (12a) and an edge (19) of the wall (12) which borders said slit (16) , the edge portions (18) of said wall (12) being free of said convolutions (15) .

A sleeve according to claim 1, characterised in that said edge portions (18) of said wall (12) each have the shape of a portion of a hollow cylinder.

A sleeve according to either one of claims 1 and 2, characterised in that said edge portions (18) of said wall (12) are between 1mm and 3mm in width.

A sleeve according to any one of claims 1 to 3, characterised in that the sleeve (10) is generally- circular in transverse cross-section and said edge portions (18) extend arcuately about the centre of the sleeve at a distance from said centre which is substantially equal to the distance from said centre to crests (15a) of said convolutions (15) .