GB2102557A - Gas rail - Google Patents

Abstract

A winged gas rail, made otherwise than by casting or extrusion, comprises a gas-distribution channel portion (10) and a control-tap mounting-plate portion (11). The mounting-plate portion (11) extends along and across the open face of the channel portion (10) such that marginal regions (12) of the mounting plate portion (11) form wings (15) of the gas rail. Holes (16) are provided in these wings (15) for the attachment of control taps (20). The gas rail can be fabricated from metal strip or by deformation of a tubular metal stock; in this latter case, the wings (15) are of double-walled form. To prevent the leakage of gas from the channel portion (10) out through the holes (16) in the gas-rail wings (15), longitudinal gas- tight seams (25) (preferably brazed seams) are formed between the channel- portion walls (13) and the mounting- plate portion (11) laterally inwardly of the holes (16) in the wings (15). <IMAGE>

Description

SPECIFICATION Gas rail The present invention relates to gas rails such as are used, for example, for the distribution of gas to the gas taps of a cooker.

More particularly, the present invention relates to a winged gas rail, made otherwise than by casting or extrusion, of the type comprising a gas-distribution channel portion, and a control-tap mounting-plate portion which extends along and across the open face of said channel portion such that marginal regions of said mounting-plate portion lie laterally beyond the walls of the channel portion and constitutu wings of the gas rail, the mounting-plate portion being formed with first holes, in said wings, for the attachment of control taps to the mounting-plate portion and second holes, in its central region above the channel portion for the transmission of gas from the channel portion to control taps attached to the mounting-plate portion.With this type of gas rail, control taps are secured to the rail by means of fixing screws passed through the holes in the gas-rail wings and engaged in the underside of the control taps. The passage of gas from the gas rail to the control taps via said second holes is sealed by means of a sealing gasket or "0" rings interposed between the control taps and gas rail around the second holes.

Although gas rails of the foregoing type can be made by casting or extrusion, various technical and economic factors render manufacture of gas rails in this manner generally unattractive.

Most gas rails currently produced are therefore either made from tube by rolling or are fabricated directly from steel strip; a typical gas rail made from tube is described and illustrated in British Patent Specification No. 1,442,763.

In the form of gas rail described in the aforesaid British Specification, the channel portion is connected to the mounting-plate portion by means of connecting wall portions which run the length of the channel portion and extend laterally out from the top of the channel-portion walls to connect with the outermost edges of the mounting-plate portion. The said connecting wall portions thus lie close up against the mounting-plate portion in its marginal regions and give the gas-rail wings a double-walled form.

Where the gas rail is formed from tube, then the mounting-plate portion, the connecting wall portions, and the channel portion are constituted by respective portions of the tube wall after deformation of the original tube; where the gas rail is fabricated from steel strip, then the said connecting wall portions will generally be constituted by the longitudinal edge portions of the length of strip used to make the channel portion, the said connecting wall portions being subsequently welded along their outside edges to the outermost edges of the steel strip forming the control-tap mounting-plate portions. In either case, the connecting wall portions are formed with holes in correspondence with the said first holes in the mounting-plate portion so as to permit the secural of taps to the gas rail by means of fixing screws inserted through the double-walled wings of the rail.

Despite the close juxtaposition of the said connecting wall portions with the marginal regions of the mounting-plate portion, the possibility still exists of gas passing into the interior of the said doublewalled wings and from there leaking out of the gas rail through the control-tap fixing-screw holes. To prevent leakage of gas in this manner, it has in the past been necessary both to provide sealing washers around the heads of the fixing screws and to arrange for the sealing gasket interposed between the control taps and rail to encircle not only the said second holes formed in the mounting-plate portion of the rail but also the said first holes through which the fixing screws pass.

Due to the number of sealing components required, the risk is ever present that a leakage may result either from the accidental ommission of one such component or from one of the fixing screws being insufficiently tightened up. Furthermore, the need to provide and position several sealing components is economically disadvantageous.

It is an object of the present invention to provide a winged gas rail of the aforesaid type, made otherwise than by casting or extrusion, which avoids the need to provide sealing components around the control-tap fixing screw holes formed in the gas rail.

According to one aspect of the present invention this object is achieved by the provision of a gas rail of the aforesaid type, made otherwise than by casting or extrusion, wherein longitudinal gas-tight seams are formed between the channel-portion walls and the mounting-plate portion laterally inwardly of said holes formed in the gas-rail wings whereby to prevent the leakage of gas from said channel portion out through the holes in the gas-rail wings.

In the case of gas rails with wings of the abovementioned double-wall form, the formation of gastight seams between the channel-portion walls and the mounting-plate portion effectively seals off the interior of the wings from the interior of the channel portion thereby doing away with the need to provide sealing components around the control-tap fixing screws inserted through the holes in the gas-rail wings.In a preferred embodiment of the invention, the longitudinal seams are brazed seams formed by depositing a predetermined quantity of brazing material at one end of the gas rail and thereafter heating the gas rail in a furnace; this treatment causes the brazing material to flow under capilliary action into the wings of the gas rail (after first melting in cases where the brazing material is provided in solid or paste form) whereby not only to form said longitudinal seams, but to also seal around the holes in the wings and provide a double barrier against gas escape. It will, of course, be appreciated that the capilliary action relied upon in the foregoing brazing method depends on the interior space of the wings being made sufficiently narrow during the manufacture of the gas rail.The capilliary-action brazing method of forming the said longitudinal seams can also be effected using braz ing materials in other forms, for example, in the form of wire extending through the interior of the gas rail.

Furthermore, various other techniques can be used to form the seams, such as electron-beam welding or the use of ceramic cements.

As well as being applicable to gas rails with wings of double-wall form, the present invention also provides for gas rails, fabricated from metal strip, which have single thickness wings. More particularly, in one embodiment the present invention provides a gas rail in which the channel portion and mounting-plate portion are formed from respective lengths of metal strip with the free ends of the channel-portion walls being abutted against the mounting-plate portion, laterally inwardly of the control-tap attachment holes formed therein, and being connected to the mounting-plate portion by respective said longitudinal seams formed, for example, by brazing or gluing. With such an arrangement there is no possibility of gas leaking out of the gas rail through the fixing screw holes. Furthermore, gas rails of this form are relatively easy and cheap to manufacture.

Afurther advantage of rails made in accordance with the invention is that since the possibility no longer exists of gas escaping through the holes in the gas-rail wings, the number and distribution of these holes is not limited by the need to seal off these holes with the gas taps and interposed gaskets. It thus becomes possible to form the gas-rail wings with two or more different sets of holes each appropriate for the fixing of a different make of tap, the fact that some of the unused holes are not covered by the taps attached to the rail being of no consequence. The positioning of the various sets of fixing holes will generally be such that the different makes of tap mate with the same gas-flow holes in the central region of the mounting plate.

The accommodation of different makes of gas tap by the same rail enables the user of the rail to use several sources for the taps without problems, which is of considerable commercial benefit. Two forms of gas rail embodying the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a cross-section through a first form of gas rail embodying the invention, the gas rail being shown with a control tap mounted thereon; Figure 2 is a plan view of a second form of gas rail embodying the invention; Figure 3 is a side elevation of the second form of gas rail; and Figure 4 is a section on line IV-IV of Figure 3, to an enlarged scale.

The first form of gas rail, shown in Figure 1, is a winged gas rail made by deforming, by rolling, a metal tube stock. The gas rail comprises a channel portion 10, and a control-tap mounting-plate portion 11 which extends along and across the open face of the channel portion 10 such that the marginal regions 12 of the mounting-plate portion 11 lie laterally beyond the walls 13 of the channel portion 10. The outermost edges of the mounting-plate portion 11 are connected by connecting wall portions 14 with the upper ends of the channel walls 13.

The connecting wall portions 14 and the overlying marginal regions 12 of the mounting-plate portion 11 lie in close proximity to each other and together define double-walled wings 15 of the gas rail.

The wings 15 of the gas rail are formed with a plurality of pairs of holes 16 for the passage of control-tap fixing screws 17 therethrough. In corres pondence with each pair of holes 16, the central region of the mounting-plate portion 11 is formed with an aperture 18 to enable the passage of gas from the interior channel portion 10 to a control tap 20 attached to the mounting-plate portion 11 by fixing screws 17 inserted through the corresponding holes 16. A sealing gasket 21 is interposed between the underside of the control tap 20 and the top of the mounting-plate portion 11 to prevent the leakage of gas passing through the aperture 18, along the interface between the tap 20 and portion 11.

The control tap 20 includes a control rod 22 operable to control the flow of gas from the gas rail, via the control tap 20, to the burner of a gas cooker.

To eliminate the possibility of gas passing from the interior of the channel portion 10 into the interior of the double-walled wings 15 and from there leaking out through the holes 16, the interior of each wing 15 is sealed off from the interior of the channel portion 10 by means of a respective longitudinal gas-tight seam 25 formed along the root of the wing 15. The seams 25 are, for example, formed by brazing after the original tube stock has been deformed into the required shape.The brazing is carried out by depositing a predetermined quantity of, for example, a copper-based brazing paste (typically 1 to 10 cc) inside one end of the gas rail at the roots of the wings 15; thereafter, the gas rail is passed through a controlled atmosphere belt fur- nace of 1.2 m in length at a rate of 15 cm per minute where it is heated to a temperature of between 1100 and 1200 C. As a result, the brazing paste melts and is drawn by capilliary action resulting from the close juxtaposition of the opposed walls of the wings 15, along the whole length of the wings 15 and laterally outwards to the tips of the wings. For effective spreading of the brazing material undercapilliary action, the spacing between the opposed walls of the wings 15 should be no greater than about 0.18 mm.

After treatment in the furnace, the gas rail is allowed to cool. Examination of gas rails treated in this manner have shown that not only are gas-tight seams 25 effectively formed but, indeed, the whole interior space of the wings 15 becomes filled in thereby forming seals around the holes 16 which together with the seams 25 present a double barrier against the escape of gas through the holes 16.

Since the escape of gas through the holes 16 is not possible with the form of gas rail shown in Figure 1.

The provision of sealing washers around the heads of the fixing screws 17 is unnecessary as is the provision of seals between the underside of the control tap 20 and the mounting-plate portion 11 in the region of the holes 16. However, for convenience, the sealing gasket 18 is extended across the whole width of the mounting-plate portion 11.

Even though the gas rail of Figure 1 has been described as being made by rolling a length of tube stock, it will of course be appreciated that the provision of the gas-tight seams 25 is equally applicable to gas rails, with double-walled wings, fabricated from metal strip.

Furthermore, although in the brazing method described above for forming seams 25, the brazing material was supplied in the form of paste deposited at one end of the gas rail, the brazing material can be supplied in other forms, for example, in solution or suspension, or as lengths of wire passed through the interior of the gas rail and held in place adjacent the roots of the wings by bending the ends of the wires around the ends of the gas rail. Another method of positioning the brazing material where required would be to provide the material in the form of foil sandwiched between the opposed walls of the wings during the initial manufacturing stages of the gas rail. Alternatively, the opposed walls could be preplated with the brazing material.

The use of a bronze alloy brazing material as an alternative to a copper brazing material is desirable in cases where the gas rail is to conduct gases containing components corrosive to brazed copper joints. Bronze alloy brazing materials also permit a greater capilliary spacing between the opposed walls of the wings 15 than copper brazes.

The seams 25 can also be formed by methods other than brazing. Thus, for example, although normal welding techniques are unsuitable for forming the seams 25 in that they would produce unacceptable distortion of the mounting-plate portion 11, electron-beam welding of the juxtaposed walls of the wings 15 at their roots has been found to provide satisfactory results owing to the precise control possible over the weld area and depth.

Another possible method of forming the seams 25 would be to use a ceramic cement drawn into the roots of the wings 15 when in a liquid form and subsequently fired.

The second form of gas rail, shown in Figures 2 to 4, is fabricated from steel strip and basically comprises a channel portion 30 of U-shaped crosssection formed from one length of steel strip, and a control-tap mounting-plate portion 31 formed from a second length of steel strip.

Prior to the joining together of the channel portion 30 and the mounting-plate portion 31, the latter portion is formed with pairs of control-tap attachment holes 32 in its longitudinal marginal regions, with gas apertures 34 formed in the central region of the mounting-plate portion 31 in correspondence with the pairs of attachment holes 32, and with four pairs of locating projections 35 pushed out from the thickness of the metal strip forming the portion 31 (the precise form and number of these projections is not critical and can be varied to suit particular requirements). The ends of the mounting-plate portion 31 are also bent down at right angles to form channel-end closure plates 36.

To assemble the gas rail, the U-sectioned channel portion 30 is positioned on the mounting-plate portion 31 between the bent up plates 36, the locating projection 35 serving to centrally locate the portion 30 on the portion 31 such that the longitudinal marginal regions of the latter project out laterally beyond the channel portion 30 and constitute wings of the gas rail. The projections 35 thus assure that the holes 32 lie outside the bounds of the channel portion 30.

The channel portion 30 can be held in position on the mounting-plate portion 31 by means of tongues (not shown) carried by the plates 36 which are bent over into contact with the bottom of the channel portion 30 once the latter has been located on the portion 31. Gas-tight joining seams 37 are then formed between the channel portion 30 and the mounting-plate portion 31. These seams 37 extend along the outside of the channel portion 30 in the corners formed between the channel walls and the mounting-plate portion 31 and continue along the zones of meeting of the channel portion 30 with the channel-end closure plates 36.

Clearly, by constructing the gas rail in this manner the possibility of gas escaping through the attachment holes 32 formed in the wings of the gas rail is completely eliminated.

In addition to the components already described, the gas rail shown in Figures 2 to 4 further comprises end mounting plates 38, and a gas feed pipe 40.

The attachment of control taps to the gas rail is effected in standard manner by fixing screws inserted through the holes 32, the use of sealing components around these screws being unnecessary.

The gas-tight seams 37 are preferably formed by brazing effected, for example, by the deposition of a bronze alloy brazing paste at spaced locations along the interface lines of the channel portion 30 and the mounting-plate portion 31,followed by heat treatment of the assembly in a furnace to cause the brazing material to flow by capilliary action along the interfaces between the portions 30 and 31. Brazing carried out in this manner will form gas-tight seams along both sides of each channel wall doubly ensuring the gas-tightness of the join between the portions 30, and 31.

The free edges of the channel walls can, if desired, be provided with inwardly or outwardly turned flanges to facilitate joining the portions 30 and 31; where outwardly-turned flanges are provided, these should not extend out as far as the holes 32.

Other brazing methods are also possible (such as the use of brazing solutions, suspensions or foil, or by pre-plating the areas to be joined). The seams 37 can be formed by methods other than brazing, for example, by glueing or by electron-beam welding.

The form of gas rail described with reference to Figures 2 to 4 is particularly advantageous in that not only does it avoid the need to provide sealing components around the control-tap fixing screws, but it is also simple and economic to manufacture.

Furthermore, by changing the form of the end mounting plates 38, the gas rail can be adapted for mounting in various different pieces of equipment.

Various modifications to the described forms of gas rail are, of course, possible. Thus, for example, the cross-section form of the channel portions 10 and 30 can be other than that shown, for example, triangular, or trapezoidal. Furthermore, the gas pipe 40 shown in Figures 2 and 3 can connect with the gas rail at positions different from that illustrated; for example, the gas pipe 40 may connect with the gas rail through one of the closure plates 36.

Although the illustrated gas rails are formed with wings along both sides, it will be appreciated that the principle of the invention is applicable to gas rail formed with only one wing; in such cases a longitudinal gas-tight seam is provided along the roof of the single wing to prevent leakage of gas from the channel portion of the rail out through the hole formed in the wing.

Claims (12)

1. A winged gas rail, made otherwise than by casting or extrusion, comprising a gas-distribution channel portion, and a control-tap mounting-plate portion which extends along and across the open face of said channel portion such that marginal regions of said mounting-plate portion lie laterally beyond the walls of the channel portion and constitute wings of the gas rail, the mounting-plate portion being formed with first holes, in said wings, for the attachment of control taps to the mounting-plate portion and second holes, in its central region above the channel portion, for the transmission of gas from the channel portion to control taps attached to the mounting plate portion; said gas rail being provided with longitudinal gas-tight seams formed between the channel-portion walls and the mounting-plate portion laterally inwardly of said first holes formed in the gas-rail wings whereby to prevent the leakage of gas from said channel portion out through the holes in the gas-rail wings.

2. A gas rail according to Claim 1, wherein the channel portion is connected to the mounting-plate portion by means of connecting wall portions which run the length of the channel portion and extend laterally out from the top of the channel-portion walls to connect with the outermost edges of the mounting-plate portion, the said connecting wall portions being formed with holes in correspondence with the said first holes of the mounting-plate portion and being juxtaposed the mounting-plate portion to give a double-walled form to the gas-rail wings, and said longitudinal gas-tight seams serving effectively to seal off the interior of the doublewalled wings from the interior of the channel portion.

3. A gas rail according to Claim 2, wherein the longitudinal seams are brazed seams.

4. A gas rail according to Claim 3, wherein the opposed interior surfaces of the gas rail wings are sufficiently close to each other that during the formation of the longitudinal seams by brazing, brazing material is drawn by capilliary action into the wings of the gas rail whereby not only to form said longitudinal seams, but also to seal around the holes in the wings.

5. A gas rail according to Claim 2, wherein the longitudinal seams are seams formed by electronbeam welding or the use of ceramic cements.

6. A gas rail according to Claim 1 fabricated from metal strip and formed with single thickness wings.

7. A gas rail according to Claim 6, wherein the channel portion and mounting-plate portion are formed from respective lengths of metal strip with the longitudinally-extending outer portions of the channel-portion walls being abutted against the mounting-plate portion, laterally inwardly of the first holes formed therein, and being connected to the mounting-plate portion by respective said longitu dinalseams.

8. A gas rail according to Claim 7, wherein said longitudinal seams are brazed seams.

9. A gas rail according to Claim 7 or 8, wherein the metal strip length constituting the mountingplate portion is formed with locating projections which facilitate the positioning of the channel portion on the mounting-plate portion during fabrication of the gas rail.

10. A gas rail according to any one of Claims 3,4 or 8, wherein a bronze alloy brazing material is used to form the said longitudinal seams.

11. A gas rail of the form set out in any one of the preceding claims with the modification that the rail is only provided with a single wing and a single said seam for preventing leakage of gas from the channel portion of the rail out through the holes in the gas-rail wing.

12. A winged gas rail substantially as hereinbefore described with reference to Figure 1 or Figures 2 to 4 of the accompanying drawings.