US3424146A - Infrared heaters and generators - Google Patents

Description

23, 1969 M; w. PATRICK ETAL 3,424,146

INFRARED HEATERS AND GENERATORS Filed March 23, 1967 Sheet of 7 INVENTORS MALCOM W PA TRICK PH/L /P M FUR/W77 ATTORNEY 5 Sheet 2 of? Jan. 28, 1969 M. w. PATRICK ETAL INFRARED HEATERS AND GENERATORS Filed March 255, 1967 INVENTORS MALCUM W. BUR/CK PH/L/P M. PORN/Tl ATTORNEY5 23, 1969 M. w. PATRICK ETAL 3,424,146

INFRARED HEATERS AND GENERATORS Filed March 25, 1967 Sheet 3 of 7 INVENTORS MALCOM W PA TRICK PH/L /P M. FOR/W77 www ww ATTORNEYS Jan. 28, 1969 M. w. PATRICK ETAL 3,424,146

INFRARED HEATERS AND GENERATORS I A of? Sheet INVENTORS MALCOM M4 PA TRICK PHIL/P M. FOR/W 7/ www Filed March 255, 1967 ATTORNEYS 23, 1969 M. w. PATRICK ETAL 3,424,145

INFRARED HEATERS AND GENERATORS Sheet Filed March 23, 1967 INVENTORS MALCOM n4 PAm/c/r PHIL/PM. FORN/T/ JM %e%%% 9 1% ATTORNEYS 28, 1969 M. w. PATRICK ETAL 3,424,146

INFRARED HEATERS AND GENERATORS Sheet 9 of 7 Filed March 23, 1967 8208M SAFETY SWITCH 4 4 M 8 Am 2 W/ HE R D Q YR TE Y Um ET L T FA Ll l S E0 2 SH R S M mm F Y RL O 9: 0.. s mw INVENTORS MALCOMWPATR/CK PH/L/PMFORN/T/ ATTORNEY5 United States Patent 3,424,146 INFRARED HEATERS AND GENERATORS Malcom W. Patrick, Chagrin Falls, and Philip M. Fornitl, Cleveland, Ohio, assignors, by mesne assignments, to White Consolidated Industries, Inc., a corporation of Delaware Filed Mar. 23, 1967, Ser. No. 625,334- U.S. Cl. 126-92 15 Claims Int. Cl. F23d 13/14; F24c 3/04 ABSTRACT OF THE DISCLOSURE Combustion type infrared generators having two relatively inclined rows of radiants providing a V-shaped radiant surface; retainers for mounting the radiants in the burner housing, which preferably has stepped sides and internal combustible mixture distributing baflles; and a curved reradiator adjacent the radiant surface. Radiant heaters having infrared generators removable through a normally open side of a heater casing and without other access to the casing exterior, a fuel-air supply arrangement and ignition and control systems.

Background and summary of the invention This invention relates to infrared generators and, more specifically, to infrared generators of the combustion type and to radiant heaters in which combustion type infrared generators are incorporated. In particular, the present invention is concerned with improved infrared generators of the type described in Patent No. 2,775,294 to Gunther Schwank and with radiant heaters for space heating and similar uses in which such infrared generators are used as the radiant energy source.

Generally speaking, the type of infrared generator with which the present invention is concerned includes a housing providing a plenum chamber for a combustible fuelair mixture and an open side which is spanned by an assembly of refractory radiants having passages for the combustible mixture therethrough. The combustible mixture is generated and flows under pressure from a premixer or aspirating type mixer into the plenum chamber and then through the radiants to a combustion zone adjacent the outer surface of the radiant assembly, heating this surface to incandescence and causing it to emit radiant energy which is primarily in the upper part of the infrared portion of the electromagnetic spectrum. In many cases a reradiator (typically a coasre mesh screen of heat resistant metal) is mounted adjacent the radiant surface to increase the eificiency of the infrared generator.

In those heretofore known infrared generators of the type just described of larger capacities there are typically two rows of radiants arranged in a planar array having a flat radiant surface. It has now been discovered that there are significant advantages in inclining the roWs of radiants relative to each other to produce a V-shaped radiant assembly with a similarly configured radiant surface. One advantage is a substantially more uniform and significantly wider distribution of the energy emitted from the radiant surface with respect to the major and minor axes of the generator. Another advantage is a surprising reduction in the size of an infrared generator of given capacity. Further advantages are a reduction in the per radiant heat load, which increases the useful service life of the radiants, improvement of the cross-lighting ability, and an increase in efficiency.

Yet another important advantage of the novel V-shaped tile arrangement described above is that it materially simplifies the task of mounting multiple rows of radiants in the generator housing. In the infrared generators of the present invention the mounting problem is even further resolved by the use of novel retainers between the rows of tiles, which lock the adjacent rows together by a keystone type effect. These retainers are completely free of mechanical connection to the generator housing and accordingly effectively accommodate contraction and expansion-induced relative movement between the rows of tiles as the infrared generator is cycled as does the V-shaped configuration of the radiant assembly, which eliminates the buckling problem appurtenant to planar arrays of multiple radiants.

Co-operating retainers of novel construction for the free edges of the radiant assembly combine with the retainers described in the preceding paragraph to fix the radiant assembly relative to the generator housing. These retainers have readily detachable radiant supporting components. Accordingly, since there is no mechanical connection between the first-described retainers and the radiants, the radiants can be easily and quickly removed from the generator housing for cleaning or replacement.

Another important feature of the present invention is a novel rerediator of curved configuration which is pref ably employed to even further increase the efliciency of the infrared generators disclosed herein. Unexpectedly, it has been found that this configuration eliminates the destructive hot spots which would form along the bend of a V-shaped reradiator and, at the same time, has no adverse effect on the uniformity of radiant energy emission which was heretofore thought to require a reradiator exactly parallel to the radiant surface of the generator.

The reradiator is mounted in spaced relationship to the radiant assembly by novel brackets which accommodate expansion and contraction of the reradiator as the infrared generator is cycled. These brackets are preferably attached to the generator housing by removable fasteners so that the reradiator may be easily and quickly removed and serviced or replaced when necessary.

Other significant features of the present invention are a novel generator housing configuration, which significantly reduces the transfer of heat from combustion products to the housing and a baflle arrangement which insures a uniform fiow of combustible mixture over the entire radiant assembly without creating an unacceptable back pressure in the plenum chamber. These features therefore also make worthwhile contributions to the operation and efliciency of the infrared generators described herein.

As mentioned above, the present invention resides, in another aspect, in the provision of novel, improved radiant heaters in which the radiant energy is supplied by combustion type infrared generators. Perhaps the most salient feature of these novel heaters is a novel, improved arrangement for mounting the infrared genera-tor in more-or-less conventionally configurated heater casing having an open bottom through which the radiant energy emitted by the infrared generator passes to the space or objects to be heated. This arrangement permits the infrared generator to be removed through the open bottom of the casing and eliminates the need for access to any other part of the casing exterior. This feature is especially important in applications such as high bray heating where banks of heaters may be mounted adjacent the roof of a building so that neither the sides nor the top of the heater are accessible without lowering the entire heater.

From the foregoing it will be apparent than one important and primary object of the present invention is the provision of novel, improved combustion type infrared generators and novel, improved radiant heaters in which combustion type infrared generators are employed as the source of radiant energy.

Other related and import-ant but more specific objects of the present invention reside in the provision of combustion type infrared generators;

1) which are capable of providing a more uniform and wider distrbiution of emitted radiant energy than those of the same general type heretofore known.

(2) which are substantially smaller for a given capacity than those heretofore available.

(3) which have a lower heat load per radiant than those heretofore known and in which the radiants accordingly have a longer service life.

(4) in Which the radiants are more effectively mounted in the generator housing than in heretofore available infrared generators of the same general type and in which the radiants are easily and quickly removable from the generator housing.

(5 in which, in conjunction with the preceding objects, the radiant energy is emitted from a radiant assembly in which adjacent rows of radian-ts are inclined relative to each other to provide a generally V-shaped configuration.

(6) which have a novel reradiator that is free from sharp bends and appertenant destructive hot spots and which have a novel reradiator mounting arrangement to accommodate temperature changeinduced distortions of the reradiator.

(7) in which the generator housing has a novel configuration capable of significantly reducing heating of the housing.

(8) which have a novel internal baffling arrangement for effecting uniform distribution of a combustible fuelair mixture.

Another important but specific object of the present invention resides in the provisions of novel, improved radiant heaters in which the source of radiant energy is a combustion type infrared generator and in which the infrared generator can be removed through one normally open side of a heater casing in which it is mounted without the necessity of gaining acces to the rest of the heater exterior.

Other objects, further novel features, and additional advantages of the present invention will become apparent from the appended claims and as the ensuing detailed description and discussion proceeds in conjunction with the accompanying drawing.

Brief description of the drawing In the drawing:

FIGURE 1 is a pictorial view of a radiant heater embodying the principles of the present invention in which the source of radiant energy is a novel improved combustion type infrared generator similarly constructed in accord with the principles of this invention;

FIGURE 2 is a partial, vertical section through the radiant heater of FIGURE 1;

FIGURE 3 is a bottom view of the combustion type infrared incorporated in the radiant heater of FIGURE 1;

FIGURE 4 is a side view of the infrared generator;

FIGURES 5 and 6 are sections through the infrared generator taken substantially along lines 55 and 6-6 of FIGURE 3;

FIGURE 7 is a partial vertical section through the infrared generator, showing in detail the novel retainers employed to support the radiants of infrared generator from the generator housing;

FIGURE 8 is an exploded view of the generator housing, the retainers employed to fix the free edges of the radiants to the housing, and a bracket employed to support a reradiator in spaced relationship to the radiants;

FIGURE 9 is a pictorial view of the reradiator and one of the reradiator supporting brackets;

FIGURE 10 is a pictorial view of the radiant heater showing the arrangement of the major components in its control compartment and the configuration of the infrared generator housing;

FIGURE 11 is a plan view of the radiant heater casing with certain top panels removed and parts broken away to show the arrangement of components in the housing;

FIGURE 12 is an end view of a combustible mixture deflecting assembly employed in the infrared generator;

FIGURE 13 is a schematic of a control system for the infrared generator;

FIGURE 14 is a chart showing the radiant energy distribution from a conventional infrared generator of the same general type as that contemplated by the present invention; and

FIGURE 15 is a graphical illustration of the radiant energy distribution from infrared generators constructed in accord with the principles of the present invention.

Detailed description of a preferred embodiment Referring now to the drawing, FIGURE 1 depicts a novel radiant heater 20 constructed in accord with the principles of the present invention. The major components of infrared generator 20 are a casing 22 housing a novel combustion type infrared generator 24 also constructed in accord with the principles of the present invention, a combustible mixture supply system 26 (see FIGURE 10) for the infrared generator, and a control and ignition system-28 (see FIGURE 13).

The details of casing 22 are unimportant and may be varied as necessary for particular applications of the present invention. Generally speaking, however, this casing includes side walls 30 and 32, removable end walls 34 and 36, and removable top panels 38 and 40 (see FIGURE 10). A partition 42 divides casing 22 into an infrared generator compartment .4 and a systems compartment 46, which communicates with the ambient atmosphere through louvers 47 in side walls 30 and 32. The bottom side of infrared generator compartment 44 is open for the passage of the radiant energy emitted from infrared generator 24, while the bottom of compartment 46 is closed by a panel 48.

In addition to the components described in the preceding paragraph, casing 22 includes various reinforcing members such as the gussets 50 shown in FIGURE 11 and the tie strap 52 shown in FIGURE 10. The details of these reinforcing members are not part of the present invention, which may be understood without reference to them. They will accordingly not be described further herein.

Referring now to FIGURES 18, the major components of the novel infrared generator 24 incorporated in radiant heater 20 are an infrared generator housing 54, a radiant assembly 56, and a reradiator 58. Radiant assembly 56 is retained in housing 54 by novel clips 60 and retainer assemblies 62; and reradiator 58 is fixed to the housing by elongated support brackets 64.

As shown in FIGURES 26, infrared generator housing 54 has parallel, opposed side walls 66, a top wall 68, and end walls 70 and 71 defining a combustible mixture plenum chamber 72. Also, with the infrared generator oriented as shown in FIGURES 2, 5 and 6, its lower or bottom side is open. Side walls 66 are stepped toward a vertical, longitudinal plane 73 through the midpoint of the infrared generator. This is an important practical feature of the present invention. Specifically, in infrared generator 24, combustion occurs in a zone 74 adjacent the outer radiant surfaces 75 of radiant assembly 56. The combustion products flow from combustion zone 74 downwardly around the lower edges of and then upwardly along side walls 66. By stepping the side walls toward the center of the infrared generator, they are to a considerable extent isolated from the combustion products, minimizing the transfer of heat from the combustion products to the generator housing. This is important in that it minimizes the heating of the combustible fuelair mixture which, as will be explained in more detail later, flows through plenum chamber 72 to combustion zone 74.

Housing 54 has another important practical advantage in that it is of sheet metal construction, thus making it materially less expensive to fabricate than the cast-type housings heretofore typically employed in infrared generators of the same general type as that contemplated by the present invention. Any appropriate sheet material may be employed with one suitable material being sheet steel coated with a conventional, high temperature resistant, procelain enamel.

As in the case of radiant heater casing 22, there are various structure details of housing 54 which are not considered part of the present invention. Therefore, to the extent that these details are not necessary to an understanding of the present invention, they will not be discussed herein.

Referring now specifically to FIGURES 2 and 7, radiant assembly 56 is mounted across and spans the open side of housing 54. Assembly 56 includes two rows or arrays 76 of radiants 78 which are substantially equal in length to housing 54 and which may be one, two, or more radiants wide. Radiants 78 may but do not necessarily have to be ceramic tile of the type disclosed in US. Patent No. 2,775,294 to Gunther Schwank. In any event, they will be provided with passages 80 for the flow of combustible fuel-air mixture from the interior of housing 54 to combusion zone 74.

One of the important features of the present invention is the mounting of the two radiant arrays 76 in mutually inclined, abutting relationship so that radiant assembly 56 has the V-shaped configuration shown in FIGURES 2 and 7. One advantage of this configuration, mentioned briefly above, is a significant improvement in the uniformity of radiant energy distribution over that obtainable from the heretofore known infrared generators of the general type contemplated 'by the present invention in which flat or planar radiant assemblies are employed.

In conjunction with the foregoing, FIGURE 14 shows the distribution pattern along the major or longitudinal axis of the conventional planar radiant assembly. The distribution pattern shown in this figure is for an infrared generator oriented so that the planar radiant emitting surface of the generator faces downwardly. Reference characters 82 and 84 respectively identify the location of the major burner axis, which extends at a right angle to the figure, and the curve tracing the distribution pattern in a plane normal to the major axis of the infrared generator of the emitted radiation.

FIGURE 15 shows a typical pattern for infrared generators constructed in accord with the principles of the present invention, reference characters 86 and 87 respectively identifying the major or longitudinal axis of the infrared generator, which extends at a right angle to the figure, and a curve showing the distribution pattern of the emitted radiation in a plane normal to the major or longitudinal axis of the infrared generator.

A comparison of FIGURES 14 and 15 shows that the distribution pattern of the infrared generators of the present invention are substantially more uniform than those of heretofore available generators of the same general type. Curves 84 and 87 also show that the infrared generators of the present invention produce a wider distribution pattern than those heretofore available, which is another significant advantage.

FIGURE 14 does not show the distribution pattern of radiant energy along the minor or transverse axis of infrared generators according to the present invention i.e., over a vertical plane including the major axis of the generator or lines parallel to the major axis. Such patterns have however been ascertained. These show that the same high degree of uniformity obtained along the major axis is also present along the minor axis, which is also a significant advantage.

The novel V-shaped radiant assembly described in the preceding paragraphs has a number of other important advantages. These have previously been discussed in considerable detail.

Referring now to FIGURES 2, 7, and 8, each of the radiants 78 is mounted in generator housing 54 in the novel V-shaped configuration just described by the clips 60 and retainer assemblies 62 mentioned above. Retainer assemblies 62 include a pair of co-operating retainer members 88 and 90 adapted to clamp a radiant therebetween. As shown in FIGURES 7 and 8, members 88 have a retaining portion 92 adapted to engage or abut the upper or inner surface of the associated radiant 78, a leg 94 adjacent the side wall 66 of housing 54 with which the retainer is associated, a leg 96 abutting an outwardly extending flange 98 at the lower edge of the housing side wall, and an upstanding flange 100. Retainer members 88 are fixed to the side walls of housing 54 as by tack weldmg.

The co-operating retainer members 90 have a generally flat configuration except that they are folded intermediate their ends to provide an abutment 102 adapted to be juxtaposed to the leg '94 of the co-operating retainer member 88. As shown in FIGURE 7, members 90 have legs 104 adapted to engage the outer or lower side of radiants 78 so that they co-operate with the legs 92 of retainer members 88 to clamp the radiants 78 therebetween. Retainer members 90 are detachably fixed to the flanges 98 of generator housing side walls 66 by bolts 106, which extend upwardly through aligned apertures 108, 110, and 112 in retainer members 90 and 88 and flange 98 and an insulating washer 113 between bracket 64 and retainer member 90, by nuts 114, and by nut retainers 116.

The method of fixing the outer edges of the radiants to the generator housing just described is also considered an important feature of the present invention because an individual radiant can be easily and quickly removed from the infrared generator for cleaning, replacement, etc. This is done simply by removing the detachable component 90 of the retainer assembly 62 fastening the radiants to the housing.

An insulating strip 118 of Fiberfrax or other temperature resistant insulation is interposed between the edge of the radiants 78 and the leg 94 of retainer member 88. This insulation reduces the transfer of heat from the radiant to the burner housing, minimizing the possibility of overheating.

Another important feature of the present invention is the novel clips 60 which connect or joint the two radiant arrays 76. These clips have a generally Z-shaped configuration and a web 120 between oppositely directed legs 122 and 124. Clips 60 are disposed at intervals along radiant assembly 56 at the intersections of adjacent radiants and in the center of each radiant.

Successive clips 60 are oriented with corresponding legs extending in opposite directions. The downward force exerted by a radiant 78 on the leg 122 of a specific clip 60 results in a corresponding downward force being exerted on the oppositely disposed radiant 78. Therefore, with radiant assembly 56 oriented as shown in FIGURE 7, clips 60 exert a keystone type locking effect on the radiants in the mutually inclined arrays 76 to retain them in the V-shaped arrangement shown in FIGURE 7.

Clips 60 are not connected to any components of infrared generator 24 except for radiants 78. Accordingly, they freely accommodate temperature-induced expansions and contractions in radiant assembly 56 caused by cycling of infrared generator 24.

As is also shown in FIGURE 7, an insulati-g member 126 of Fiberfrax or other heat resistant material is interposed between the two radiant arrays 76 to seal the joint therebetween and prevent the formation of hot spots. Also, because of it resiliency the Fiberfrax material acts as a cushion between the mitered faces of the radiants as they expand during heating to minimize the abrasive action between the mitered faces.

The precise angle between the two radiant arrays 76 is not critical and may vary from installation to installation. This is not to be understood, however, as meaning that there are no limits on this angle. Specifically, if the included angle between the two rows of radiants is too large, making the V more shallow, the desired uniformity of radiant energy distribution will not be obtained; and, moreover, the keystone type of lock between the two rows of radiants will be lost, producing the same mounting problems encountered in conventional, multiple row radiant assemblies. Conversely, if the angle between the two rows of radiants is made too small and the V becomes too steep, the distribution of radiant energy will not be uniform; and, in addition, there will be an undesirably high interchange of heat between the two rows of radiants, resulting in over-heating of the radiants.

In practice, included angles on the order of 150 have been found acceptable in that the desired pattern of radiation is obtained; and, at the same time, structural integrity of the radiant assembly is obtained. Different angles can of course be employed, if desired.

Referring now to FIGURES 37, a channel 128- is fixed to generator housing 54 on the back or inner side of radiant assembly 56 along the intersection 130 of the two radiant arrays 76-. Channel 128, which is free of mechanical connections to radiants 78, supports the radiants and maintains them in the configuration of FIG- URE 7 during shipping and at other times when the radiant is not in the downwardly facing orientation shown in FIGURE 7 and in which the keystone locking effect obtained with the radiant assembly in this position is not present.

A strip 131 of asbestos or other insulation fixed to the web 132 of channel 128 minimizes the transfer of heat from the radiant assembly by conduction through clips 60 and the channel 128 to housing 54. This is also helpful in preventing overheating of the housing.

In addition to performing the function just described, channel 128 is connected by braces 134 (see FIGURE 3) to the walls 66 of housing 54 at intervals along the housing. This arrangement adds rigidity to the generator housing.

Referring now to FIGURES 1, 2, and 9, reradiator 58 is mounted in spaced relationship to radiant assembly 56 to increase the efficiency of infrared generator 24 in a known manner. Reradiator 58, which will typically consist of one or more sections of coarse mesh screen of temperature resistant metal such as Nichrome or Inconel (three sections are employed in the illustrated embodiment to minimize distortion), has a continuously curved configuration in the vicinity of the intersection 130 between the two radiant arrays 76. This eliminates the sharp bend which would be necessary at this point if the heretofore deemed necessary practice of maintaining precise parallelism between the radiant surfaces and reradiator of an infrared generator were to be followed. By eliminating such a bend, the destructive hot points which form along such bends are also eliminated, materially increasing the service life of the reradiator. At the same time, it has been found that the lack of parallelism in this vicinity surprisingly does not adversely affect the uniformity of emission from radiant surfaces 75 of radiant assembly 56 to a significant extent.

Referring now to FIGURES 2 and 7-9, the brackets 64 "by which reradiator 58 is supported from generator housing 54 are eleongated, sheet metal members having integral mounting legs 138 and reradiator supporting legs 140. Brackets 64 are detachably fixed to the flanges 98 of generator housing 54 by the same bolts 106 securing retainer members 90 to these flanges. This permits the reradiator to be readily removed from infrared generator 24 when necessary.

As is best shown in FIGURES 8 and 9, inwardly directed flanges or lugs 142 are struck from legs 140 at intervals therealong. The reradiator 58 rests on lugs 142 and is loosely secured to the lugs by pig rings 144 which flllith the radiant surfaces 75 facing downwardly, each radiant array 76 would be accordingly inclined at an angle on the order of 15 to the horizontal.

8 are fastened through the reradiator and apertures 146 in bracket legs 140.

The mounting arrangement just described maintains reradiator 58 in the proper position relative to radiant assembly 56. At the same time, this mounting arrangement, together with the reradiator configuration described above, accommodates temperature change induced distortion and movement of the reradiator as infrared generator 24 is cycled.

Referring now to FIGURES 1, 2, and 11, infrared generator 24 is removably mounted in radiant heater casing 22 by four bolts (not shown). Two of these extend vertically through slots 148 in a bracket 150 attached to generator housing end wall 70 and apertures 152 .in a bracket 154 fixed to radiant heater casing end wall 36. These bolts fix bracket 150 to bracket 154, supporting end 70 of infrared generator 24 from end wall 36 and are accessible from the bottom of the casing 22 through the generator compartment 44.

The second set of bolts extend horizontally through openings 156 in an L-shaped bracket 158 fixed to generator housing end wall 71 and aligned apertures 160 in radiant heater casing partition 42. The bolts accordingly fix the opposite end of infrared generator 24 to the partition 42 and are accessible from the bottom of the casing 22 through the systems compartment 46 by removing the panel 48.

In conjunction with the generator mounting arrangement just described, the overall plan dimensions of the infrared generator are smaller than the corresponding dimensions of the open bottom side of casing 22. Accordingly, when desired, infrared generator may be easily and simply removed from casing 22 by removing the two bolts attaching the infrared generator to partition 42 and loosening the two by which it is fixed to bracket 154 and then removing the infrared generator through the bottom of the casing.

Moreover, since all four bolts are accessible through the bottom of casing 22, infrared generator 24 can be removed without the necessity of gaining access to the remainder of casing 22. This is particularly import-ant in applications such as high bay heating where radiant heaters 20 may be arranged in closely spaced side-by-side relationship and in juxtaposition to the roof of a building or other structure in which case access to the sides and top of the heater could be obtained only by lowering it. Accordingly, the novel method of mounting the infrared generator in casing 22 just described is considered an important feature of this invention.

Referring now to FIGURE 10, the combustible mixture supply system 26 of radiant heater 20, which is mainly conventional, includes a fuel supply line 161 extending through casing side wall 30 into compartment 46, where it is connected to a solenoid valve 162. The latter is, in turn, connected through line 164 to a conventional orifice member 166. The later is mounted by a spider 168 in the bell 170 of a venturi assembly 172, which also includes a venturi tube 174 extending through the end wall 71 of infrared generator 24 into the interior of generator housing 54 and through partition 42 into systems compartment 46.

Venturi bell 170 is fixed to heater casing partition 42 by a U-shaped bracket 176 and is free of mechanical connections to infrared generator 24. Venturi tube 174 is fixed to infrared generator housing 54 by the L-shaped bracket 158 mounted on housing end wall 71 and by a bracket 178 which is attached to the top wall 68 of generator housing 54. A tube 180 sealed to venturi tube 174 and the opening 182 for the venturi tube in end Wall 71 isolates plenum chambetr 72 from systems compartment 46.

From the foregoing, it will be apparent that venturi tube 174 is fixed only to infrared generator 24 and is free of attachment to casing 22. The flared inlet end 184 of the venturi merely has a sliding fit over the outlet end 186 of the entrance bell mounted in the casing. This arrangement further facilitates the removal of the infrared generator from casing 22 since no dismantling of the combustible mixture supply system is required when the infrared generator is removed.

The aspirator type fuel-air supply system thus far described operates in the conventional manner with the flow of gas under pressure through orifice member 166 inducing a flow of air into venturi assembly 172. As the gas and air flow through venturi tube 174, they are mixed; and the combustible fuel-air mixture is discharged from the venturi tube into the pletnum chamber 72 in the interior of generator housing 54.

- Referring now to FIGURES 3 and 4, turning vanes 190 and baflles 192 and 194 are employed to obtain a uniform distribution of the combustible mixture through-v out plenum chamber 72. Bafiies 192 and 194 are generally flat sheet metal members extending between channel 128 and the side walls 66 of housing 54 at a level generally coincident with the bottom of venturi tube 174. Baflies 194 are located at the end of housing 54 opposite venturi assembly 172, and baflles 192 are located in spaced rela-. tion to the outlet end of venturi tube 174 approximately midway between .the ends of housing 54.

As best shown in FIGURES 3, 4, and 12, turning vanes 190 are arcuately sectioned sheet metal members having a straight lower edge 196 and a curved upper edge 198. The turning vanes are mounted in side-by-side relation in plenum chamber 72 with their concave surfaces spanning chamber 72 and facing the outlet end of venturi tube 174. The bottom edges of the turning vanes rest on the laterally extending baflles 192 just described and extend upwardly from these baffles to the .top wall 68 of housing 54. Due to the configuration of the upper edges 198 of the turning vanes, there are openings 200 between the turning vanes and housing 54 through which the combustible mixture can flow toward the end of the infrared generator opposite the venturi assembly.

As indicated above, the baffling arrangement just described is effective to provide a uniform distribution of the combustible mixture throughout the plenum chamber. At the same time, this particular baffling arrangement does not create an objectional back pressure in the plenum chamber so it is considered an important practical feature of this invention.

From plenum chamber 72, the combustible mixture flows through the apertures 80 in radiants 78 to combustion zone 74. Here the fuel-air mixture burns, heating radiants 78 and reradiator 58 to incandescence, causing them to emit radiant energy which is primarily in the infrared portion of the spectrum.

Reflectors 202 (part of which are shown in FIGURE 1) attached to the side walls 30 and 32 of casing 22, to partition 42, and to end wall 36 may be provided to direct the radiant energy emitted from radiant surfaces 75 and impinging on them back through the open bottom of the casing into the area or onto the objects being heated. Reflectors 202 are fixed to the associated casing components by appropriate brackets (not shown) which position them at the desired inclination relative to the components on which they are mounted. Preferably, detachable fasteners are employed to fasten the reflectors to these brackets so that they can be removed when necessary.

The remaining major components of radiant heater 20 is the control and ignition system 28 mentioned briefly above. This may be of any desired construction with one suitable system being the DSAN-DSAL model available from the assignee of the present invention.

The details of this system are not part of the present invention; and they will, accordingly, not be described in detail herein. Generally speaking, however, this system (see FIGURES l and 13) includes a thermostat or other switch S204 which, when closed, initiates operation of infrared generator 24 by completing a circuit through the heater R206 of a safety switch S208 located in generator compartment 44 and incorporated in the system to shut it down on ignition failure. A second circuit is simultaneously completed through a flame detector S210 extending through openings 212 in partition 42 and 213 in infrared generator end wall 71 to a position adjacent one of the radiant surfaces 75 of radiant assembly 56. The flame detector is incorporated in the system to shut down the heater if the supply of power or fuel fails while the system is in operation.

A third circuit is completed at the same time as the two just described. This is through the coil of relay K214, which is also mounted in compartment 46.

Energization of relay K214 causes relay contacts K2141 and K214-2 to close, energizing the solenoid of and opening valve 162. The opening of valve 162 allows fuel to flow from line 161 through the valve and line 164 to plenum chamber 72 and, also, through a line 218 extending through opening 212 to a pilot burner (not shown) disposed beside flame detector S210 adjacent radiant assembly 56.

The closing of the relay contacts also energizes ignition transformer T219, providing a spark across the gap of sparkplug 220, which is located adjacent the pilot burner to ignite the latter. The pilot burner then ignites the main burner; and, thereafter, the flame detector operates to de-energize relay K214, shutting off the ignition transformer and the flow of current through the safety switch heater R206. At this point, the control system is in the normal on configuration.

Unless there is a fuel or power failure, the system will remain in this on configuration until the demand for heat is satisfied. At this time switch S204 will open, interrupting the flow of current through the solenoid of valve 162 which will close, interrupting the flow of fuel to infrared generator 24.

In the foregoing discussion, infrared generator 24 has been described by reference to one exemplary application; viz, its utilization in a radiant type space heater. It will, however, be readily apparent to those skilled in the arts to which the present invention pertains that the type of infrared generator disclosed herein is not limited to this particular application. On the contrary it may readily be employed in any other application for which infrared generators of the same general type are useful.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent is:

1. An infrared generator of the combustion type comprising a housing having an open side and defining a fuelair plenum chamber; an assembly of radiants spanning the open side of said housing, said radiants having fuelair flow passages therethrough; and means for effecting a flow of combustible fuel-air mixture from said plenum chamber through said flow passages to a combustion zone adjacent the exposed side of said radiant assembly to heat said radiants to temperatures at which they will emit radiant energy which is primarily in the infrared portion of the electromagnetic spectrum; said radiants being arranged in two separate arrays each having a generally planar radiant face and said infrared generator further including means for mounting said radiant assembly in said casing with the two arrays of radiants in side-by-side relationship and abutted along a line extending longitutudinally of said housing and with the two arrays of radiants outwardly diverging relative to each other to form a generally V-shaped assembly in cross-section,

whereby the radiant energy emitted from the radiants in said assembly and transferred therefrom will be substantially uniformly distributed with respect to the major and minor axes of the infrared generator.

2. The infrared generator of claim 1, together with at least one reradiator of heat resistant metal fixed to said housing in spaced relation to said radiant assembly, said reradiator spanning said radiant faces and having a concave, smoothly curved configuration to thereby eliminate sharp bends and the destructive hot spots associated with such bends while retaining a substantially uniform exchange of energy between said reradiator and the radiant faces of the radiant assembly.

3. The infrared generator of claim 2, wherein the means for fixing said reradiator to said casing comprises reradiator-supporting brackets fixed to said housing on opposite sides thereof and adapted to have the opposite edges of said reradiator rested thereon and retainer means for loosely fastening the reradiator to said brackets to thereby retain said reradiator on said brackets while accommodating expansionand contraction-induced movement of said reradiator relative to said brackets during the cycling of the infrared generator.

4. The infrared generator of claim 1, wherein the in eluded angle between the radiant faces of the two arrays of radiants is on the order of 150.

5. The infrared generator of claim 1, wherein said flow effecting means comprises means for supplying the combustible fuel-air mixture to said plenum chamber and communicating with said chamber through an inlet opening in one end of said housing and including mixture distribution means in said housing and extending laterally across said plenum chamber for effecting a generally even distribution of the fuel-air mixture along the length of the plenum chamber.

6. The infrared generator of claim 5, wherein said mixture distribution means comprises arcuately sectioned bafiles disposed in side-by-side relationship across said plenum chamber and extending from the inner faces of said radiant assembly toward the side of the housing opposite the radiant assembly, the concave sides of said baffles facing the inlet opening in said housing.

7. The infrared generator of claim 1, wherein said housing has side walls extending normally from the open side thereof and wherein each of said side walls is stepped toward a longitudinal midplane through said housing normal to the open side of said housing to reduce the transfer of heat to said housing from combustion products flowing from the combustion zone around the edges of the side walls at the open side of said housing and upwardly along said side walls.

8. An infrared generator of the combustion type comprising a housing having an open side and defining a fuelair plenum chamber; an assembly of radiants spanning the open side of said housing, said radiants having fuel-air fiow passages therethrough; and means for effecting a fiow of combustible fuel-air mixture from said plenum chamber through said flow passages to a combustion zone adjacent the exposed side of said radiant assembly to heat said radiants to temperatures at which they will emit radiant energy which is primarily in the infrared portion of the electromagnetic spectrum; said radiants being arranged in two separate arrays each having a generally planar radiant face and said infrared generator further including means for mounting said radiant assembly in said casing with the two arrays of radiants in side-by-side relationship and abutted along a line extending longitudinally of said housing and with the two arrays of radiants inclined relative to each other to form a generally V-shaped assembly, whereby the radiant energy emitted from the radiants in said assembly and transferred therefrom will be substantially uniformly distributed with respect to the major and minor axes of the infrared generator and means for mounting said infrared generator with the open side of the generator facing in a generally downward direction and wherein the two arrays of radiants in the radiant assembly slope downwardly from the center of said housing toward the sides thereof with the infrared generator thus oriented, the means for mounting said radiant arrays in said housing including first radiant retaining means fixed to the side walls of said housing at intervals therealong for supporting the opposite side edges of said radiant assembly relative to said housing and second radiant retaining means between said radiant arrays at intervals along said assembly for positioning the abutted edges of the two radiant arrays relative to each other, each said second retaining means having a first portion adapted to engage the inner side of a radiant in one array and the exterior side of a radiant in the other array, each said second radiant retaining means being free of attachment to said housing.

9. The infrared generator of claim 8, together with high temperature resistant insulation between and separating the juxtaposed edges of the two arrays of radiants.

10. The infrared generator of claim 8, together with a stop member mounted in the generator housing and extending generally the length of the plenum chamber closely adjacent the radiants and along the intersection of the two radiant arrays for supporting the radiants at their juxtaposed edges when said generator is oriented so that the radiant faces of the assembly are facing in any but a generally downward direction.

11. The infrared generator of claim 8, wherein each said first radiant retaining means comprises a pair of cooperating retainer members having portions adapted to engage opposite sides of a radiant to retain it therebetween, with said first retainer members being permanently fixed to said housing, and means for detachably fixing the second retainer members to the associated first retainer members to thereby facilitate the removal of the radiant assembly from the generator housing.

12. The infrared generator of claim 11, together with high temperature resistant insulation between the retainer members in each said first radiant retaining means for thermally isolating the edges of said radiant assembly from the generator housing.

13. The infrared generator of claim 11, together with reradiator-supporting brackets for supporting a reradiator from the generator housing in spaced relation to the radiant faces of the radiant assembly, said brackets being detachably fixed to the first retainer members of said first radiant retaining means by the means fixing the cooperating second retainer members thereto.

14. The infrared generator of claim 8, wherein each said second radiant retaining means is a generally Z- shaped member of heat resistant metal having a web adapted to be disposed between the two radiant arrays and legs on the opposite ends of said web providing said first and second radiant engaging portions.

15. A radiant heater for space heating and the like comprising a casing having an open side, an infrared generator of the combustion type in said casing and oriented to project the radiation emitted from its radiant surfaces through the open side of said casing, said infrared generator comprising a housing having an open side and defining a fuel-air plenum chamber; an assembly of radiants spanning the open side of said housing; said radiants having fuel-air fiow passages therethrough; and means for effecting a fiow of combustible fuel-air mixture from said plenum chamber through said how passages to a combustion zone adjacent the exposed side of said radiant assembly to heat said radiants to temperatures at which they will emit radiant energy which is primarily in the infrared portion of the electromagnetic spectrum; said radiants being arranged in two separate arrays each having a generally planar radiant face and said infrared generator further including means for mounting said radiant assembly in said casing with the two arrays of radiants in side-by-side relationship and abutted along a line extending longitudinally of said housing and with the two arrays 13 of radiants outwardly diverging relative to each other to form a generally V-shaped assembly in cross-section, whereby the radiant energy emitted from the radiants in said assembly and transferred therefrom will be substantially uniformly distributed With respect to the major and minor axes of the infrared generator, and means in said casing for supplying a fuel-air mixture to the infrared generator, the overall dimensions of the opening in the casing being larger than the corresponding dimensions of the infrared generator, said infrared generator being fixed to said casing solely by fasteners accessible through the open side of the casing and the infrared generator being free of mechanical connections to the combustible mixture supply means whereby said infrared generator can of and Without access to the remainder of the exterior of the casing.

References Cited UNITED STATES PATENTS 2,051,213 8/ 1936 Hamilton. 3,237,679 3/1966 Best. I 3,291,115 12/ 1966 Forniti. 3,359,965 12/1967 Milligan.

FOREIGN PATENTS 1,131,710 10/1956 France.

JAMES W. WESTHAVER, Primary Examiner.

US. Cl. X.R.

be removed from said casing through the open side there- 15 43 l-329, 354

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