US2171275A - Heating unit - Google Patents

Description

Aug. 29,1939. J. R. MORRISON HEATING UNIT Filed Aug. 12, 1937 2 Sheefis-Sheet 1 I F I ll Ill/(3% ifalin/fl ;nm'som,

Patented Aug. 29, 1939 UNITED STATES HEATING UNIT John R. Morrison, Hudson, Ohio Application August 12, 1937, Serial No. 158,718

6 Claims.

This invention relates to a heating unit for circulating and re-circulating heating systems.

It is a common practice to provide heating systems for ovens and furnaces in which the atmosphere of the oven is recirculated, continuously, through the heating device. The source of heat is an open flame in a combustion chamber, through which chamber the gaseous medium circulates. The heat is transferred to the gaseous medium by contact with the flame and mixture of the products of combustion with the gaseous medium. Such heating systems are provided with one or more fans, for maintaining re-circulation of the oven atmosphere through the oven and through the combustion chamber.

Heretofore, the common practice has been to provide a heater, having a combustion chamber, as a unit separate from other parts of the heating system. The common practice has been to provide a fan as a unit separate from the heater. The fan and heater are connected together by suitable ducts, and the heater and fan are connected with the oven by suitable ducts. The ducts are fabricated at the factory, and assembled and insulated at the location of installation. This practice is unduly expensive because the operation of setting up the heater and the fan is special with each installation, requiring much time and labor under expert supervision. Such installations involve considerable heat loss in the connections between the several units. The friction loss in the fluid flow is high. Both effects lower the efficiency of the system.

The common practice has been to join the dis- ,charge opening of the heater with an intake opening of the fanywhich intake opens into the fan housing axially, relative to the impeller. The fan shaft extends from the fan housing at the side opposite from the intake opening. The fan shaft is supported by bearings arranged outside of the fan housing, the fan impeller being supported upon the free end of the shaft. The nature of this mounting for the fan impeller is such that the impeller must be relativelynarrow in order not to impose undue strains upon the shaft or bear- J' mgs. Consequently, fans of adequate capac1ty are large in diameter and expensive, due especially to the bearing structure.

It is an object of this invention to provide a heater unit which includes both the source of heat supply and a fan for maintaining circulation and re-circulation of gaseous medium. It is an object to provide a heating unit in which the burner and the fan are combined in a single chamber with accompanying economies in fabrication and gains in efliciency of operation. It is an object to provide a unit in which the burner and the fan are combined in a single chamber, provision being made both for protecting the fan from high temperatures associated with the flame and for free flow of gaseous medium through the chamber. It is an object to provide a fan having intake openings at both sides of the fan housing, the shaft and impeller being supported by bearings at opposite sides of the impeller and to provide for cooling the fan shaft at the bearings. It is an object to provide a fan and heating unit adapted for combination with an oven with a minimum use of ducts.

It is an object to provide a fan and heating unit, the burners and fan being arranged in a common chamber, and to provide for accessibility to the interior of the chamber for servicing purv poses;

Other objects and advantages of the present invention will appear in the following detailed description, taken in connection with the accompanying drawings, in which:

Figure 1 is a view, partly in cross section and partly in side elevation, illustrating a heating unit of this invention.

Figure 2 is a view, partly in cross section and partly in end elevation, of the device shown in Figure 1.

Figure 3 is a detailed view of a heat radiating device, which is a part of the device of Figures 1 and 2.

Figure 4 is a partial view, partly in section and partly in side elevation, of a modification of the heating unit of Figure 1.

Figure 5 is a view in side elevation, illustrating other features of the form of invention shown in Figure 4.

The functions essential to a heating unit, for the circulating and re-circulating type of heating system, are to maintain a localized flame, as the source of heat supply, and to impell the gaseous medium through its circuit of travel. A burner I, is provided for maintaining a localized flame of any suitable gaseous or liquid fuel, supplied to the burner through connection 2. Air for maintaining combustion is supplied through the aspirator intake 3, which is adjustable. The burner is conventional. A fan housing is shown at 4, the housing having gas intake openings 5. Certain features of novelty of the fan construction will appear in the following description.

Economies of construction and improved efliciency, due to reduced heat losses, are attained by arranging burner I and the fan housing 4 together in a chamber 6. Chamber 6 serves as a combustion chamber, for the flame issuing from the burner l. Block I, of refractory material, is arranged immediately in front of burner I, the flame impinging upon the block 1. The functions of block I are to shorten the flame and to disperse the products of combustion widely through the combustion chamber.

The flame issuing from the burner I tends to create movement of gases through the combustion chamber in a forward direction from the burner. The fan 4 is located in line with and in front of the burner, where the products of combustion and the gaseous medium are most accessible to the fan intake. v

The high temperature of the flame and the heat radiation from the flame together would be destructive to the material of the fan housing, if the latter were exposed thereto. To protect the fan housing, a partition 8 is located adjacent to the fan housing, between the fan housing and the burner I. The partition 8 is, as shown in Figure 2, of such sizeas completely to obstruct the fan housing 4 to radiation from the flame. The partition 8 is of fire-resistant heat insulating material. A composition of asbestos and cement is suitable for the purpose. The chamber 6 is sufllciently wide to provide passages 9, around the edges of partition 8.

Under the pressure gradient afforded by suction from the fan, the hot gaseous medium and products of combustion flow through the combustion chamber, and around partition 8 into the fan housing, with very little resistance. The resistance to gas flow afforded by this construction, is less than that inherent inthe operation of burner and fan systems known to the priorart.

The fan 4 is located wholly within the combustion chamber where both sides of the fan housing are equally accessible. to the gaseous medium. Openings 5 are provided in each side of the fan housing. The fan shaft in extends through openings 5 and through apertures H in the side walls of the housing l2. Brackets ll, detachably mounted on the side walls l2, support bearings l4 in which the ends of the shaft l2 are journalled for rotation. A sheave I5 is fixed on one end of the shaft. Belt l6 and electric motor I! supply power for turning the shaft Ill and the impeller,

Since the shaft III for the fan impeller is supported at both ends, the width of the fan impeller may be greater, as compared to the width of the fan impeller practicable in those types of fan construction where the impeller is mounted on the free end of the shaft. By making the fan impeller of adequate width, full-advantages may be taken of the double intake openings 5 and, at the same time, the dimensions ofthe fan housing may be relatively small, for a given fan capacity. The fan impeller is shown in dotted line at l0.

The comparatively small size of the fan housing, made possible by the increased width of the fan, is of importance where the fan is arranged in the combustion chamber. Such a fan may be placed in a combustion chamber without unduly increasing the size of the housing as compared to the housing required for the heater alone. As will be apparent from the showing in the drawings, the size of the fan is commensurate with the size of the burner and the combustion chamber. a

It is necessary, in the operation of the re-circulating type of heating system, to vent a small proportion of 'the re-circulating gaseous medium to the atmosphere. The vented gases make room for fresh air necessary to maintain combustion. Also, in order to provide an adequate quantity of gaseous medium to effect heat transfer in the oven, and to maintain an average gas temperature at a predetermined level, excess fresh air is introduced continuously into the system. The excess fresh air intake is indicated at l8. A reglater I! is provided which is adjustable to control the volume of excess fresh air. The register It opens into a passage through the housing into the combustion chamber.

The housing I2 is made up of the panels 2|.

, A panel 2| is constructed of metal sheets 22 and The 23 which extend between channels 24. margins of the metal sheets 22 and 23 are bent around the sides of the channels 24 and secured thereto. The channels 24 provide strength for the panels and support the metal sheets 22 and 23 in spaced relation. The space between the sheets 22 and 23 is filled with"insulating material 25, such as mineral wool or the like. The panels 2| are, joined at the corners by angle irons 26. At the bottom of the housing, angle irons 21 extend around the exterior of the corners, and are secured to walls of adjacent panels. The angle irons 21 afford adequate strength and rigidity to support the housing when being handled. At the top, sheet metal angles 28 enclose the corners. Insulating material such as mineral wool is packed within the corners, as indicated at 29. It will be apparent that, except for the passages through the wall of the housing, to accommodate the various operating parts, the chamber 6 is completely surrounded by insulation. There is little opportunity for the escape of heat from the chamber 6 and, since both the burner and the fan are contained within that chamber, but little loss of heat can occur between those parts of the heating system, as compared to the losses common to the heater and fan combinations in common use. By virtue of the compact fan and the close coupling between the burner and the fan, the housing 2 forms a very compact unit which affords all of the operating functions essential to the recirculating type of heating systems. The high temperature at which the fan impeller operates tends to raise the temperature of the fan shaft at the bearings, and to heat the bearings, shortening their life and making lubrication difiicult. To avoid excessively high temperatures at the bearings, the

impeller shaft is cooled at both ends.

To 0001 the shaft, heat radiators, 30, are provided at each end of the shaft. The heat radiators 30 are located within passages l I through the housing wall. The passages II are sumciently large to afford considerable clearance for the heat radiators. The passages I I are open to permit flow of air through the passages in heat transfer relation with the radiators 30. The re- 1 duced pressure within the housing afforded by operation of the fan 4, at the region where the passages H open into the housing, causes air to flow from the atmosphere through the passages II and over the radiators 30. The relatively cool air, from the atmosphere, absorbs a large part of the heat flowing along the shaft l0 toward the bearings l4. The operation of the last described cooling device maintains the temperature of the shaft, and the bearings, sufllciently low for satisfactory operation.

the oven with which the openings 33 and 34- register. In such case the heating unit may be arranged in operative combination with the oven simply by juxtaposing that side of the heating unit, having the apertures 33 and 34, against the side of the oven having the mating passages. In such case, the fan will operate to discharge gaseous medium directly into the oven chamber and the return flow of gaseous medium will occur directly from the oven chamber through opening 34 into the combustion chamber.

It will be obvious that the openings 33 and 34 may be located in various places and various walls of the heating unit. The location of the openings 33 and 34 is determined by the layout of the oven installation, there being no restrictions as to the side wall in which the openings are located, nor as to the precise location of the openings in any side wall, imposed by the operation of the heating unit. It will be apparent that the fan 4 may be arranged within the chamber 6 in a variety of positions to connect the discharge side of the fan with an opening, such as indicated in 33, provided either in the top wall, the end wall, or the bottom wall of the housing.

A large opening 35, through a wall of the housing is provided for access to the interior of the housing for servicing the fan. The opening 35 normally is closed by cover 36, containing adequate insulation to prevent heat loss. In assembling the fan in the housing, it is introduced into space 6 through the opening 35, the block 1 and partition 8 and their supporting angle irons 31 not being in place at the time, for unobstructed access to the interior of the housing. After mounting the fan, the angle irons 31 are secured in place and block I and partition 8 inserted therebetween. The cover 36 is arranged in place, as shown, preparatory to operation of the heating unit.

Figures 4 and show a modification of the invention. The housing structure, and the burner and air intake openings, (not shown) are the same as those illustrated in Figure 1. The device of Figures 4 and 5 differs from that of Figures 1 and 2 in the arrangement of the fan within the space 40 of the housing 4|.

The axis of the shaft 42, for the fan impeller, is located equi-distantly from the top wall, the bottom wall, and the end wall of the housing. As shown in full line, in Figure 4, the discharge nozzle 43 of the fan is arranged in communication with a passage 44 through the bottom wall of the housing. As shown in dotted line, in Figure 4, the nozzle 43 is arranged to discharge hot gaseous medium through an opening 45 in the end wall of the oven chamber. And, as shown in dot and dash line, in Figure 4, the nozzle 43 is arranged. to discharge hot gaseous medium through an opening 46 in the top Wall of the housing. It will be observed that the location of the shaft 42 is the same for all three positions.

In practice, the housing panels are built up, in the manner described in connection with Figure 1 the panels being standard for a given size of heating unit. When the panels are assembled to make a housing for a particular installation the location of the discharge opening, through the housing, is determined by the layout of the heating system. An opening, either in the bottom panel, in the end panel, or in the top panel, is made to receive the nozzle 43 of the fan. In mounting the fan within the housing, it is so arranged as to discharge through the hole proof the fan shaft making possible complete freedom of choice in arrangement of the fan housing.

Figure 4 merely shows three possible positions of the fan housing, it not being intended that three openings be provided in the housing. The .three positions of the fan housing, shown in Figure 4, differ only in angular displacement about the shaft. Instead of shifting the fan housing angularly about the shaft, the fan may be removed, as a whole, from the housing of the heating unit, and turned around, end for end, and returned to thecombustion chamber By so re-arranging the fan the nozzle 43 may be shifted to a position, relative to that shown infullv line in Figure 4, where the nozzle lies on the left hand side of the vertical central line through the fan, instead of on the right hand side of that line as shown at present in Figure 4. Likewise, by turning the fan, end for end, the nozzle may be arranged, relative to the dotted line position shown in Figure 4, so as to connect with an opening through the bottom of the end panel, instead of with an opening through the top of the end panel as shown at present in Figure 4. Also, such fan re-arrangement may be utilized to change the nozzle to a position, relative to the dot and dash line position shown in Figure 4, where the nozzle will lie on the right hand side of the vertical central line through the fan, rather than on the left hand side of that line as shown at present in dotted line in Figure 4. From the foregoing it will be apparent that there are six different positions, for the discharge of the fan about that end of the heating unit housing where the fan is located.

Another advantage of this construction is that, if alterations, after installation, should require, the discharge opening, through the housing of the heating unit, may be changed from one wall to another wall without alteration in the mounting of the fan except to turn the fan housing about the shaft, or to turn it end for end. In such case a new opening may be cut through another wall of the heating unit housing, the old opening being closed by a suitable plug.

The modification of the invention, shown in Figures 4 and 5, differs from that, shown in Figures 1 and 2, in still another respect. Instead of providing an opening in the top of the heating unit housing, for access to the interior, both for mounting the fan and for servicing it, another arrangement is provided, as shown in Figure 5.

Referring to Figure 5, an opening 41 is provided through the side panel of the heating unit housing.

The opening 41 is closed by a cover plate 48, suitably insulated. The cover plate 48 is bolted to the heating unit housing as indicated at 49. The cover plate 48 carries one of the bearings till for the fan shaft. When installing the fan, the cover plate 48 is removed and the fan is arranged in place. Servicing the fan may be attended to in the same way. After either installation or servicing of the fan the plate 48 is bolted in place, the shaft 42 of the fan being received in the bearing 50. The essential difference between the structure of Figure 5 and that of Figure 1 is that, upon removing the cover plate-48, the fan becomes more accessible for servicing or for removing either the impeller or the housing than is the case with the construction of Figure 1.

While the invention has been described in detail, by way of illustration, it is not intended so to limit the invention. Variations in the'details of construction may be made, as will be apparent to one skilled in the art, without departing from the scope of the invention as defined in the following claims.

What I claim as my invention is as follows:

1. A heating unit comprising, in combination, a heating unit housing having heat insulating walls and inlet and outlet openings, and affording -a substantially closed chamber, a burner for maintaining combustion within the chamber, a fan housing within the chamber, the fan housing having intake openings in opposite side walls and an outlet opening communicating with the outlet opening in said heating unit housing, said side walls of the fan housing being spaced from,

the walls of the heating unit housing within the chamber, a shaft and impeller in the fan housing, said impeller being mounted on the central portion of the shaft, the ends of said shaft extending through said fan housing intake openings and through apertures in opposite side walls of the heating unit housing, bearings located exteriorly of the heating unit housing for rotatably supporting 'both ends of the shaft, and means for driving the shaft and impeller in rotation.

2. A heating unit comprising, in combination, a heating unit housing having heat insulating walls and having an inlet and an outlet opening, and affording a substantially closed chamber, a burner for maintaining combustion within the chamber, a fan housing within the chamber, the fan housing having intake openings in opposite side walls and an outlet opening communicating with said outlet in said heating unit housing, .said side walls of the fan housing being spaced from the walls of the heating unit housing within the chamber, a shaft and impellerin the fan housing, said impeller being mounted on the central portion of the shaft, the ends of said shaft extending through said intake openings and through apertures in opposite side walls of the heating unit housing, bearings located exteriorly of the heating unit housing for rotatably supporting both ends of the shaft, a heat radiating device mounted on each end of the shaft and located within the apertures through the heating unit housing, said apertures permitting flow of air from atmosphere in heat transfer relation with said devices and into the chamber, and means for driving the shaft and impeller in rotation.

3. A heating unit comprising, in combination, an insulated wall heating unit housing affording a substantially closed chamber and having an inlet and an outlet opening, a burner for maint'aining combustion in the chamber, a non-insulated fan housing arranged wholly within the chamber, there being intake openings in opposite side walls of the fan housing and an outlet connected with said heating. unit housing opening, a partition so arranged in the chamber as to shield the fan housing from radiation from the region of combustion, a shaft and impeller in the fan housing, the impeller being mounted on the central portion of the shaft, the ends of the shaft extending through said intake openings and through apertures in opposite side walls of the heating unit housing, bearings mounted exteriorly of said heating unit housing for rotatably supporting the ends of said shaft, said partition and said fan housing being spaced from the walls of said heating unit" housing so as to provide for free movement of gases from the regions of combustion, around the partition, and

to the fan intake openings, and means for driving the shaft and impeller in rotation.

4. A heating unit comprising, in combination, an insulated-wall heating unit housing affording a substantially closed chamber and having inlet and outlet openings, means for maintaini'ng combustion in the chamber, a fan housing arranged in said chamber, a shaft and impeller in the fan housing, the impeller being mounted on the central portion of the shaft, the fan housing having intake openings in opposite side walls and an outlet connected to the outlet in said heating unit housing, said side walls of the fan housing being spaced from the walls of the heating unit housing, said shaft extending through said intake openings and through apertures in opposite side walls of the heating unit housing, bearings mounted exteriorly of the heating unit housing for rotatably supporting the ends of the shaft, the shaft extending parallel to and equi-distantly from the top wall, the bottom wall, and the end wall of said heating unit housing, and means for driving the shaft and impeller in rotation.

5. A heatingunit, comprising, in combination, an insulated wall heating unit housing affording a substantially closed chamber having inlet and outlet openings, means for maintaining combustion in the chamber, a fan housing arranged in said chamber, a shaft and impeller in said fan housing, the fan housing having intake openings in opposite side walls and an outlet opening communicating with the opening in said heat unit housing, said side walls of the fan housing being spaced from the walls in the heating unit housing, said shaft extending through said intake openings and through an aperture on one side wall of the heating unit housing, there being an opening in the opposite side wall of the heating unit housing permitting access to the fan for mounting, removal, and servicing of the fan, a heat insulating cover for the opening, there being an aperture through the cover, the other end of said shaft extending through said aperture, bearings mounted exteriorly of the housing for rotatably supporting the ends of the shaft, and means for driving the shaft and impeller in rotation.

6. A heating unit, comprising, in combination, an insulated wall heating unit housing affording a substantially closed chamber and having an inlet and an outlet opening, means for maintaining combustion in the chamber, a fan housing arranged in said chamber, a shaft and impeller in said fan housing, the fan housing having intake openings in opposite side walls and an outlet opening communicating with said outlet opening in said heating unit housing, said side walls of the fan housing being spaced from the walls of the heating unit housing, said shaft extending through said intake openings and through an aperture on one side wall of the heating unit housing, there being an opening in the opposite side wall of the heating unit housing permitting access to the fan for mounting, removal, and servicing of the fan, a heat insulating cover for the opening, there being an aperture through the cover, the other end of said shaft extending through said aperture, bearings mounted on the exterior face of said side wall and on the exterior face of said cover for rotatably supporting the ends of the'shaft, and means for driving the shaft and impeller in rotation.

JOHN R. MORRISON.-

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