US2894107A - Ignition proof heater - Google Patents

Description

July 7, 1959 F. L. LEFEBVRE 2,894,107

IGNITION PROOF HEATER Filed Feb. 9, 1956 INVENTOR. FL. LE FE a wee United States Patent IGNITION PROOF HEATER Fredrick L Lefebvre, Twinsburg, Ohio .ApplicationFebruary v9, 1956, Serial No. 564,415

4 Claims. (Cl. 219-34) This invention relates to radiant heaters and primarily to construction ofheaters in such a manner and :using means that will make the sameignition proof.

More particularly this invention involves tubular fused quartz radiant .heater parts which are fitted with metal .caps,:the metalcaps being suitably sealingly engaged, and arranged so as to be mechanically connected to the parts mentioned.

At present when it is desired to seal the ends of the quartz tube in which abeater element is located, some difiiculty and delay is encountered since ceramic cements are used and require relatively long hardening periods. In addition electrical connections must be supplied and fastened to the heating elements for con- .tact means. Where something other than ceramic cement is used, sealing is not presently as effective as desirable, when conditions are encountered where flame propagation may take place as a result of contact of combustible material with a heated resistance element or elements.

Another problem heretofore existing is that the leads to the heating element have been merely wire of some 'kind and thus required the step of connecting the same to a suitable source of power as well as necessarily extending through the cement at the end of the tube to thereby present a possible source of leakage.

The objects of this invention are to overcome all of the foregoing problems among others and primarily to broadly provide a unitary, ignition proof quartz tube heating unit easily and simply connected and disconnected for replacementor other purposes.

A further object ofthe invention is to provide for the sealing of tube contact andclosure means to the quartz tube at the ends thereof by means of sprayed metal which will result in a mechanical engagement of the said means and tube as well.

An even more specific object of the invention is to avail of metal cap parts, seated at the ends of a quartz tube or sheath, said parts being mechanically connected and sealed to said ends, a suitable resistance element being provided in the sheath and connected to the caps whereby the same comprise contact members to in turn be readily engaged with -co-mating members.

Other and further objects of the invention will be understood from-aconsiderationof the specification appended hereto and shown in the drawing wherein:

Figure 1 is a perspective 'view of aheater constructed iniaccordance with this invention showing certain of the contact means and parts hereof.

Figure 2 is a view in bottom elevation showing the heater units in place in the heater, the view being fragmentary in some respects.

Figure 3 is a fragmentary, somewhat enlarged, perspective view showing the manner of engagement of the cap on a quartz tube with a co-mating contact part.

Figure 4 is a View in longitudinal section showing a heater unit constructed in accordance with this invention and somewhat fragmentary in nature.

Figure 5 is a greatly enlarged fragmentary end section of a heater unit such as shown in Figure 4 to more clearly indicate the manner of connection of the cap and heater element therewith.

Figure 6 is a sectional view taken about on line 6-6 of Figure 2, looking in the direction of the arrows.

Referring now to the drawing, it will be seen as shown in Figure 1 that the heater hereof comprises a generally rectilinear pan-like part including a transverse section denoted 1 which may be the bottom or the top as desired having offstanding therefrom at right angles thereto the sides 2 and 3.

Extending transversely across the heater between the sides 2 and 3 at opposite ends are the stiffening and positioning members 4 and 5 which members are substantially identical and provided at suitable intervals'in their edges with the notches as shown in Figure 1 indicated at (S the members 4 and 5 being fastened in any suitable or preferred manner to the parts 2 and 3 as well as the bottom or transverse part 1.

The notches 6 are so arranged as to support therewithin the heater units generally denoted 7, all of them being substantially identical and thus described as comprising as seen in Figure 4 a tubular sheath 8 formed of fused quartz or the like, fused quartz having been found to be most particularly satisfactory for this purpose, being a suitable resistance element Within the sheath or tube 8 and denoted 9 this element being formed of any suitable resistance material.

Since the tubular part 8 or sheath as the case may be is of substantial length in most instances so as extend from end to end of the heater, it is equipped at its ends with a cap 10 at one end the cap 11 at the other end being substantially identical thereto.

The caps 19 and 11 are of metal preferably and arranged so that the heating element 9 may be engaged therewith to provide suitable electrical contact the caps 10 and .11 being seated on the ends of the sheath 8 so as to be virtually frictionally engaged therewith.

The caps 10 and 11 are cup-like parts formed of relatively thin gauge metal, and are mounted as shown on the ends of the tube or sheath 8 and bonded or sealed thereto as will now be described.

it has been found desirable, and in fact feasible to avail of metal spraying technique to elfect the connection of the caps and tube. The sprayed metal seal effectively prevents the heating element 9 from causing an explosion when the heaters are used in areas where flammable vapors are present.

In order to effect the connection generally described, the sheath 8 is mounted in any suitable machine whereby the same may be rotated. The end of the sheath is thereafter heated to about 700 F. while being rotated, and the caps positioned at the ends as shown in Figure 4. When the caps and end portion of the sheath have been thus heated, a metal spray gun is directed toward the extremities of the caps which are denoted 14 and 15. The metal is caused to coat the sheath and caps at the joint and while the sheath is rotated the material adheresthereto and builds up a coating indicated at 12.and 13 in the figures.

A metal sprayed as above set forth, provides a bond to the cap as will be evident and is known. In addition the hot metal spray also etches the exposed surface of the sheath adjacent the end 15 of the cap for example as is indicated in Figure 5. The result of this procedure is to produce a mechanical bond of the cap 11 as shown to the sheath 8, and in addition effect a seal or barrier to prevent entrance of vapors to the interior of the sheath.

It hasbeen found that the sealing operation described is very complete and connection of the cap thereby excellent, when aluminum is sprayed as set forth.

Other metals of course may be used in the lieu of aluminum which metals will suitably engage with the cap such as 11 and likewise result in mechanical connection with the tube or sheath.

Metal such as copper and similar metals may be sprayed by suitable apparatus so as to afford the coating at 12 and 13 as the case may be and effect the seal and result desired.

It will be understood in view of the foregoing that since the caps iii and 11 are sealingly engaged with the ends 8 of the sheath or the tube 8, there will be no Way for vapors to enter into the interior of the tube or sheath and thus the same is ignition proof in the best manner. Further since the resistance element 9 may be secured as at 16 and 17 to the respective caps 10 and 11, so as to eifect proper flow of current to energize the element 9, the caps 10 and 11 serve an additional purpose.

As shown in Figure 3 in somewhat enlarged condition, .a cap such as 11 is mounted on and engaged with the tube or sheath 8, cap 11 in turn being received in a contact member such as 19 which includes the contact parts 21 and 23 extending from the base member 25. The base member is secured to the part 1 previously mentioned but insulated therefrom as by means of a piece of insulation 27, suitable nuts and bolts such as 23 being provided.

It will be apparent that the construction just above described in detail is duplicated at the opposite end of the sheath and provided for the cap. As indicated in Figure 1 suitable leads such as 3t} may be connected to the nuts and bolts 28 to conduct the current to the contact parts such as 19 and caps such as 11 and then to the elements 9 within the sheaths 8, the caps 10 being connected similarly as will be apparent.

It will be readily understood that a series of sheaths and corresponding parts as described in reference to Figures 3 and 4 may be provided and mounted as shown in Figures 1 and 2 as Well as 6 so that the heater will develop the amount of radiation required for a particular purpose.

In addition in order to make most eflective use of the radiation developed in the respective series of heater units 7, as seen in Figure 6 a series of reflectors designated 34 may be furnished, these reflectors being arcuate in cross section and extending from end to end of the heater. They are engaged with the transverse members 4 and but spaced slightly from the part It so that insulation material such as indicated at 35 may be inserted therebetween. The reflectors 34 may of course be suitably polished so as to most advantageously reflect radiation and the insulation 35 may be of any suitable type for the purpose.

In view of the above described arrangement of parts, it will be readily understood that should any heater unit such as 7 for some reason or another become inoperative, the same may be simply removed by disengagement from the parts 19 at one end. The parts corresponding to the parts 19 are designated 20 at the other end, having the spring parts 22 and 24 similarly formed to the parts 21. and 23 and a base 26 connecting the same, suitable insulating material 29 being provided as will be apparent with bolts such as 28 being used at both ends and being similarly arranged with. leads such as 30 previously described,

Of course the other cap such as 1!]! may be disengaged from the spring members 22 and 24 and thereby enable the removal of the entire heater unit such as 7 and replacement of the same by a similar heater unit.

Thus the contact parts including the caps 10 and 11 may in addition to sealing parts also provide contact for the heating elements Within the heating unit in a way not presently possible in similar or comparable units.

By way of example suitable mounting members may be fastened to the parts 1 the members being designated 38 to thereby enable the positioning of the heaters in any preferred manner.

In view of the foregoing it will be readily apparent that a novel heater has been provided in which quartz tubes or sheaths may be used and preferably connected to metal caps, the caps in turn being sealed in engagement with the quartz tubes or sheaths by means of mechanically sprayed metal to thereby seal the caps in place and at the same time mechanically connect the same to the ends. The caps afiord not only closures for the ends of the tube but contact members which may be engaged in corresponding co-mating contacts provided in the heater which will enable ready removal of and replacement of the heater units described. As part of the main purpose of the invention, the provision of the sealed arrangement is such that ignition of vapors is prevented by reason of the sealing of the caps on the quartz sheath by means of metal sprayed as described.

I claim:

1. In a radiant heater of the class described, in combination, a tubular quartz sheath, an electric heating element therein and cap members seated on each end of the sheath so as to close the same, said members being sealingly engaged with the sheath by metal spray material to prevent ignition of material by said heating ele ment, at least one of said cap members comprising an electric contact, the heating element being connected thereto.

2. In a radiant heater of the class described, in combination, a tubular quartz sheath, a resistance heating element in said sheath, a cap member seated at each end of the sheath, and means for fastening the caps to the sheath so as to seal the same comprising sprayed metal, said sprayed metal likewise constituting a mechanical fastening.

3. The combination as claimed in claim 2, wherein the cap member constitute electrical contact members and the heating element is connected thereto.

4. The combination as claim in claim 2, wherein the cap members are cup-like metal parts and surround respective end portions of the sheath, the edges of said cups being sealingly connected to the sheath as stated.

References Cited in the file of this patent ED STATES PATENTS 555,259 McElroy Feb. 25, 1896 1,032,267 Bastian July 9, 1912 2,215,587 Kerschbaum Sept. 24, 1940 2,290,088 Blenkley July 14, 1944 2,405,089 Craig July 30, 1946 2,462,020 Craig Feb. 15, 1949 2,535,268 Coats Dec. 26, 1950 2,658,984 Mohn Nov. 10, 1953 FOREIGN PATENTS 110,240 Switzerland aaaaaaaaaa (ill cita 1,, 1925

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