Title:
FLEXIBLE ELECTRICAL HEATING ASSEMBLY
United States Patent 3806703


Abstract:
A heating assembly having two flexible electric heating devices laid side by side, each comprising blocks of heat conductive material and an electric resistance heating element passing through said blocks. Retaining means for the heating devices comprising an elongate member passing across both devices and two retaining members each having an aperture through which this elongate member passes. A block in one heating device is embraced by part of one retaining member and a block in the other heating device by part of the other retaining member and the retaining members can be manipulated by bending tag means on them to release the elongate member from them so that the elongate member can be withdrawn from the apertures by turning the retaining members about the blocks which they embrace.



Inventors:
LODGE V
Application Number:
05/299088
Publication Date:
04/23/1974
Filing Date:
10/19/1972
Assignee:
ELECTROTHERMAL ENG LTD,GB
Primary Class:
Other Classes:
219/476, 219/532, 219/539, 219/549, 338/213, 338/317
International Classes:
H05B3/00; H05B3/58; (IPC1-7): H05B3/02
Field of Search:
219/532,539,537,550,476,477,478,463,525,542,549 338
View Patent Images:
US Patent References:
3694628FLEXIBLE HEATING UNIT WITH SEPARATELY REPLACEABLE HEATING ELEMENTS1972-09-26McGwire et al.
3673387ELECTRIC HEATERS1972-06-27Drugmand et al.
3108174Heavy duty heaters for gases1963-10-22Hynes
3105134Heat conductive ground cover1963-09-24Liu
3045097Electric heater1962-07-17Sellers
3036191Radiant heating panel1962-05-22Aitken et al.
3036187Flexible electric heater1962-05-22Goldstaub et al.
3016441Split strap supporting means for electrical insulators1962-01-09Hackman et al.



Foreign References:
GB321503A1929-11-14
GB833045A1960-04-21
Primary Examiner:
Mayewsky, Volodymyr Y.
Attorney, Agent or Firm:
Stevens, Davis, Miller & Mosher
Claims:
I claim

1. An assembly comprising two flexible electric heating devices laid side by side, each comprising blocks of heat conductive material and an electric resistance heating element passing through them, said heating element being electrically insulated from said blocks, and retaining means for the heating devices comprising a plurality of elongated metal bands extending across the heating devices and two retaining metal members for each metal band, one of each said two retaining members comprising a part embracing a block in one heating device and the other comprising a part embracing a block in the other heating device and each having an aperture through it through which the elongate metal band passes and each comprising two arms extending in the same direction as one another from opposite ends of an interconnecting piece and tag means at the end of one arm which can be bent to release the elongate metal band so that it can be withdrawn from the aperture by turning the retaining member about the block which it embraces.

2. An assembly according to claim 1 in which said tag means are two tags on each retaining member on opposite sides of a T-shaped opening in said arm of the retaining member, the cross-arm of the T-shaped opening constituting said aperture and the bottom of the stalk of the T-shaped opening being at the tip of the arm.

3. An assembly according to claim 2 in which said one arm is longer than the other arm.

4. An assembly according to claim 1 in which each retaining member has two arms extending in the same direction as one another from opposite ends of an interconnecting piece and the retaining members have tag means, at the end of one arm of each of them which have been bent to secure them to the blocks after the retaining members have been arranged to embrace them.

5. An assembly according to claim 4 in which there are two tags on each retaining member on opposite sides of a T-shaped opening in the arm, the bottom of the stalk of the T-shaped opening being at the tip of the arm.

6. An assembly according to claim 1 in which the retaining members embrace blocks at the edges of the heating devices which are narrower than blocks away from the edges.

Description:
PRIOR ART

An assembly is known from U.S. Pat. No. 3,036,187 comprising a surface to be heated and two flexible heating devices laid side by side on said surface, each comprising an electric heater element passing through blocks of heat resistant material. In this known assembly the two heating devices are connected together by fasteners each of which embraces a block at one end of one row of the blocks in one of the heating devices and a block at one end of one row of the blocks in the other heating device.

The surface to be heated may, for example, be the surface of a vessel used in a chemical process and it may be encircled by a ring of heating devices, each as described above and each adjacent two connected together as described above. This assembly has the disadvantage that when one of the heating devices has to be removed, because it has failed or it is no longer desired to have a heating device at that location or it is desired to have a heating device at that location which will have a greater or lesser heating effect, the removal of this one without all the others falling off or at least some of them moving is difficult to achieve. It is an object of the invention to overcome this problem.

THE INVENTION

According to the invention there is provided an assembly comprising, two flexible electric heating devices laid side by side, each comprising blocks of heat resistant material and electric resistance material passing through them, and retaining means for the heating devices comprising an elongate member extending across the heating devices and two retaining members one comprising a part embracing a block in one heating device and the other comprising a part embracing a block in the other heating device and each having an aperture through it through which the elongate member passes and each comprising two arms extending in the same direction as one another from opposite ends of an interconnecting piece and tag means at the end of one arm which can be bent to release the elongate member so that it can be withdrawn from the aperture by turning the retaining member about the block which it embraces.

Each retaining member preferably has one of its arms longer than the other. At the end of each arm there may be a tag or tags, which in the case of one arm may be bent to release the elongate member, as mentioned above, and in the case of the other arm the tag or tags may have been bent to secure the retaining members to the blocks after the retaining members have been arranged to embrace the blocks. At the end of each arm there is preferably a T-shaped opening through the arm, the cross-arm of the T extending across the arm perpendicular to its length and the bottom of the stalk of the T being at the tip of the arm so that two tags are formed at the end of the arm on opposite sides of the stalk of the T. In the case of one arm, the cross-arm of the T constitutes the aperture mentioned above and this is the longer arm in the case where the two arms are not equal in length.

An example in accordance with the invention is described below with reference to the accompanying drawing, in which:

FIG. 1 shows an assembly of a surface to be heated, two heating devices and retaining means for them, and

FIG. 2 shows in perspective part of the retaining means of FIG. 1.

FIG. 1 shows a flexible electric heating device 1 and part of a similar device 2, the two being placed side-by-side on a surface 3 which is to be heated. There could be further similar heating devices to the left and/or the right of those shown and/or in front of and/or behind those shown. Each heating device comprises similar blocks 4 of heat-resistant and electrically insulating material arranged in parallel rows parallel to the edge shown lowermost of the device 1 and narrower blocks 5 of the same material similar to one another at the ends of alternate rows to make the heating devices rectangular without their edges being castellated. An elongate electric heater element passes, perpendicularly to the rows, through the blocks, which are pivotally connected together so that the arrangement is flexible. The heating devices themselves are disclosed more fully in U.S. Pat. No. 3,036,187, have been well known for some years and have been available from Electrothermal Engineering Limited of London, E. 7., England.

On the sides of the heating devices 1 and 2 which are remote from the surface 3 there are elongate members in the form of metal bands 6 of rectangular cross-section, each of which passes through respective apertures in two retaining members 7 which hold the device 1 and two retaining members 7 which hold the device 2. FIG. 2 shows one retaining member 7, which is made of a single piece of sheet metal which is bent so as to have two arms 8 and 9 extending in the same direction as one another from opposite ends of an interconnecting piece 10, the device being approximately U-shaped, except that the arm 9 is longer than the arm 8. The aperture through which one of the bands 6 passes is referenced 11 and it is constituted by the cross-arm of a T-shaped opening through the arm 9, this cross-arm extending across the arm 9, perpendicularly to its length. The bottom of the stalk of the T is at the tip of the arm 9 and on opposite sides of the stalk there are tags 12. When the heating devices are in normal use, these tags lie in the same plane as the remainder of the arm 9, as shown in the drawings. Without cutting or breaking the retaining member 7 or the band 6 or making the member 7 lie at the end of the band, mere manipulation of the retaining member, by bending the tags 12 until they project along the band and no longer lie above the band, will release the band so that it can be withdrawn from the aperture 11 by gentle relative movement between the member 7 and the band, without making the member 7 lie at the end of the band.

There are tags 13 on the arm 8, formed in a similar way to the tags 12 on opposite sides of the stalk of a T-shaped opening through the arm 8. After the portions 10 and 8 have been made to embrace one of the blocks 5, the tags 13 have been bent to secure the retaining member to the block. Only the thickness of the sheet metal of which the member 7 is made separates the block 5 from the surface 3.

It will be seen that each heating device has three bands 6 extending across it and these pass through six retaining members 7 for each heating device, although of course there could be more than three bands extending across each heating device and in addition to, or instead of, the retaining members 7 at the edges of the heating device there could be slightly modified retaining members 7, i.e., wider ones, engaging blocks nearer the centre of the heating device and with the bands passing through apertures in them. If there are more than the illustrated two heating devices, all of them will be secured in position in the way described above.

If a faulty heating device is to be removed and replaced by another, or if a satisfactory heating device is to be replaced by one giving a greater or lesser heating effect, or if the position of a heating device is to be adjusted, the heating device in question may be freed for movement, without disturbing the positions of any of the others and without disturbing the bands 6, by bending as described above the tags 12 of all the retaining members 7 engaging that heating device and causing these members 7 to rotate about the blocks 5 so that they come completely away from the bands 6, whereupon the heating device can be slid away in the direction of the arrow 14 or in the opposite direction. By a reverse operation, a new heating device can be fitted in place of the removed one.

FIG. 1 also shows a buckle 15 for connecting two lengths of the band 6.

Wires may be used instead of the bands 6, with slight modification of the retaining members 7.