US2263098A - Furnace - Google Patents

Description

Nov. 18, 1941. I LER- FURNACE Filed Nov. 16, 1939 4 Sheets-Sheet l INVENTOR Z2 1. Mueller I ORIVE Y Nov. 18, 1941.

M. MUELLER 2,263,098,

FURNACE Filed Nov; 16, 1939 4 Sheets-Sheet 2 BY g A TTOZLNEY M. L. MUELLER Nov. 18, 1941.

FURNACE Filed Nov. 16, 1939 4 Sheets-Street 5 INVENTOR J. Muzzle;

l I! I TORNEY 0 In- I Nov. 18, 1941. L. MUELLER FURNACE Filed Nov. 16, 1939 4 Sheets-Sheet 4 [N VENTOR Mari walla/1 BY A NEY Patented Nov. 18, 1941 UNITED STATES PATENT OFFICE FURNACE Moritz L. Mueller, Grosse 'Pointe, Mieh., assignor to Borg-Warner Corporation, Chicago, 111., a. corporation of Illinois Application November 16, 1939, Serial No. 304,677

4 Claims.

This invention relates generally to -furnaces and has particular reference to a furnace which is arranged to positively circulate and filter the air being heated.

It is an object of this invention to provide a furnace in which the novel arrangement of the parts of the furnace provide for an efficient and compactly arranged furnace so that the overall dimensions are relatively small.

It is another object of this invention to provide a furnace which may be prefabricated in sections so that very little work is required in the field to assemble the furnace.

It is another object of this. invention to provide heat exchange surfaces within a furnace in such a manner as to make use of practically all the heat generated by the burner.

It is another object of this invention to provide a furnace in which the draft within the combustion chamber is maintained at a relatively constant figure-by means of a suction blower in the exhaust passage to the chimney.

Itis another object of this invention to provide a furnace in which power for the process of combustion and power for circulating theair being heated is provided by a single motor.

Other objects and advantages of this invention will be apparent from a consideration of the fol- .lowing specification taken in conjunction with the accompanying drawings of which there are four (4) sheets and in which:

Fig. 1 represents a cutaway perspective view of the furnace embodying my invention, some of the parts of which having been omitted for the sake of clarity in the drawings;

' Fig. 2 represents a vertical section taken along the line 2-2 of Fig. 1 and looking in the direction of the arrows;

Fig. 3 represents a partially broken away section taken generally along the line 33 of Fig. 1;

Fig. 4 is a perspective view of a partially assembled furnace embodying my invention;

Fig. 5 represents a section taken along the line 5-5 of Fig. 3 and showing the type of joint used to connect the two sections of my furnace;

Fig. 6 represents a perspective view, partially broken away, of the heat exchange surfaces and combustion chamber used in my furnace; and

Fig. '7 shows a circuit diagram of the wiring connection used in operating my furnace.

Manufacturers have tried for some time to develop a furnace of relatively large heating capacity which may be more or less completely assembled at the plant under expert supervision and sent out into the field and installed in the users home with very little labor on the part of the installing agent. This not only reduces the amount of tools and parts which the agent must keep on hand, but also provides for more perfect inspection of the assembly and insures better operation of the furnace after it has been installed. To this end, I have designed a furnace which may be divided generally into three sections. Each section may be individually assembled under expert direction at the factory and shipped to the agent to be installed in the user's home.

As is illustrated in Fig. 1, my furnace consists generally of an outer casing l0 having a return air opening l2, a'heated air discharge or plenum chamber l4, and enclosed within the casing a combustion chamber [6, a radiator l8 surrounding the combustion chamber, a circulating blower 20, 'a draft inducing blower 22, fuel pump and motor assembly 24, filters 26 and various duct forming partitions which will be more particularly described later. Access to the interior of the furnace is obtained through a door 28 in the front of the casing.

As illustrated in Figs. 2, 3 and 4, the casing of my furnace consists of panels which may be made up as single stampings or sections having flanges 30 for bolting the various sections together. I have shown the sections of the casing to be made as two parts 32 and 34 each of which includes a side, half of the back and portions of the top and front of the casing. Each section is further divided along a horizontal plane approximately in the middle of the fur-' 40 which defines a plenum chamber between itself and the partition 38, and defines a combustion and heating compartment between itself and the rear .wall of the casing. The partitions 3B and 40 are out near their midsections along a vertical line and each half is joined to its respective half of the outer casing. The sections of the partitions are then joinedby means of the joint illustrated in Fig. 5 which consists of, a return flange 42 on each part of the partition and a drive cleat 44 adapted to be driven over each ofthe return flanges. 4| indicates a cleanout port and 43 indicates a port for installing a thermostatic limit switch.

The casing is further divided from the top to the bottom by an arcuate panel 46 which defines, between itself and the top of the casing, an air intake and filter chamber. The panel 46 is attached, as by welding, to one side of the casing at 48 and curved upwardly over and down the opposite side of the casing at 58 to form a duct-between itself and the casing leading to the air circulating blower 20. The panel extends from the rear wall of the casing to the partition 48. As in the case of the partition panels 38 and 40, the panel 46 is divided near its midsection so that each half may be assembled with its respective part of the casing proper. The two sections of this air duct partition may be fastened to the rear wall of the casing and to thepartition 40 by means of a flange 52 along its edges welded to the connecting part.

Near the lower portion of the casing proper, I have provided a horizontal partition panel 56 which formsin conjunction with the air duct partition 46 and the vertical partition 40, a heat exchange chamber adapted to enclose the combustion chamber I6 and radiator I8. The panel 56 has an opening 58 for receiving the discharge from the circulating blower 28. As in the case of the other partition panels, the panel 56 is divided into two sections for assembly with each section of the outer casing.

The forward partition 38 does not extend as far down the casing as does the partition 40 and the lower end of the space between the partitions is closed off from the machine space within the casing by means of a horizontal panel 68 which is also divided along the middle portion. The panel 68 may be formed by bending over the bottom portion of the panel 38. When the panel 68 is sealed to the partition 48, it forms, in conjunction with that panel and partition 38, a plenum chamber extending upwardly to the opening l4 which is then attached to the heat distributing system in the house.

The partition panel 40 has a circular opening 62 out near its midsection which is of such a size as to register with a flange on the radiator which will be described later. The partition 38 has a somewhat smaller circular opening 64 which is concentric with the opening 62 and arranged to register with the end of the combustion chamber as will be described later. The lower portion of the partition 40 has a small circular opening 66 cut in it immediately below the opening 62. This opening 66 is arranged to register with the exhaust connection from the radiator as will be more particularly described later. The middle of the panel 48 may be sup ported from below by a panel 68 which fits around the opening 66 and extends to the floor underneath the casing. .The panel 68 serves to reenforce the various partitions where they are fastened in the center of the casing since these partitions support the combustion chamber and radiator.

The heat exchan e surfaces, or radiator, and combustion chamber are more clearly illustrated in Fig. 6 and consist of a circular drum 18 forming the combustion chamber and having a flange 12 on its forward end. The rear end of the cylinder 10 is closed by a panel I4. Around the cylinder 10 is arran ed an inner cylinder 16 and an outer cylinder 18 which are connected and closed at each end by rings or plates 80 and 82. It should be noted that the inner cylinder 16 is slightly longer than the outer cylinder I8, thus forming a flange 84 at the forward end of the radiator. The two cylinders I6 and 18 thus form an annular passage which is divided into a spiral passage by means of a spiral fin 86. This fin 86 is formed of two angle members 88 and 90, one of which is welded to the outer cylinder and one of which is welded to the inner cylinder in confronting relationship with the first angular member. This spiral work construction is more particularly described and claimed in my U. S. Letters Patent for Air conditioning apparatus," No. 2,172,399, dated September 12, 1939.

The combustion cylinder I0 has an opening 92 at the top and towards the rear end of the cylinder. This opening 92 is connected by means of a short section of pipe 94 with a corresponding opening 96 in the inner cylinder I6 of the radiator. This passage allows the hot gases from the combustion chamber to escape to the spiral passage of the radiator. The pipe 94 also serves to support the radiator with respect to the rear end of the combustion chamber cylinder. The forward end of the radiator is held in position relative to the combustion chamber by means of the struts 85.

The forward end of the combustion chamber cylinder may be lined with a heat resisting material, such as fire brick, to prevent the burning of the metal at a point adjacent the end where the flame is propagated. I have shown this fire brick to consist of a circular lining 98, an end disc I00 with a hole $02 in the center thereof, and a baiile I84 toward the rear end of the flame retaining section of the combustion chamber.

It is to be noted that the combustion chamber cylinder I8 is considerably smaller than the inner cylinder I6 of the radiator, thus, there is provided an annular space between the radiator and the combustion chamber through which air is adapted to pass into the plenum chamber. The flange 84, on the radiator registers with the opening 62- in the partition panel 48 and may be fastened thereto as by bolting or welding. The opening 64 in the partition 38 registers with the flange 12 on the forward end of the combustion chamber, and these parts may be joined as by bolting or welding. The forward end of the combustion chamber and radiator assembly is thus supported upon the partition panels 38 and 40. The rear end of the combustion chamber may be further supported from the casing by means of a pipe I04 bolted or fastened to the rear end of the combustion chamber and passed through the casing as at I06. The circular plate I08 is positioned directly behind the combustion chamber to shield the outside wall of the casing from heat radiated from th combustion chamber. The plate may be held in spaced relation with the casing by means of a series of clips IIll At the front of the radiator, and at the bottom thereof, I have provided an opening I I2 to which is connected a short pipe section H4 which projects through the hole 66 in the partition 48 and forms an exhaust opening for the radiator.

After the fire brick 88, I00 and I84 has been inserted into the combustion chamber, the front plate H3 is then bolted over the front of the combustion chamber. Plate II3 has a thick ened portion or boss formed in the center thereof as indicated at H5. This boss 5 forms a burner unit having an inwardly conical bore I I6 and radially arranged holes II8 extending into a central bore I28 which communicates axially with the hole I02 in the insulating material or fire brick I00. A burner nozzle I22 is positioned within the conical opening H6 as are two ignition electrodes I24, for igniting the mixture of oil and air passing through the opening.

burner to cease.

@ aaoaoss The air for heating the house is circulated through the house by means of the blower 28 which consists of a wheel or fan I80 positioned within a hood I02 having the intake opening I34 and a discharge opening 58 opening into the space around the radiator. The fan is provided with a pulley wheel I88 for rotating .the fan wheel by means of a belt drive from the motor.

with a pulley I48 which is adapted to. drive the belt for driving the blower pulley I38. Also pipe I58 to the chimney. The base I42 has attached thereto a crossbar member I80 for fastening the machine support to the blower and to the supporting panel 88 thus insuring that the parts will be in proper alignment.

The controls and wiring for operating the furmice, as viewed in Fig. 2, consist of a terminal box I84, a thermostatic switch I88, provided supported in the top of the casing by means of angle members 21 fastened along the wall of the J I The conditioning of the air within the furnace is provided by means of the filters 28 which are casing and along the partition 40 as well as across the center of the air intake chamber. The air may be humidified by means of a body of water positionedinthe-pan l80 at the bottom of the plenum chamber. The water supply may be kept at a constantlevel by means of afloat valve I82 connected to the pan I80 by a pipe Ill and to which a supply from the water system of the house is connected. In case the filters 28 should become clogged, I have provided a by-pass damper I84 for the purpose of allowing air to escape past the clogged filters. In this manner there is no danger of there being a lack of air passing over the radiator and combustion chame her, and, thus, overheating is prevented. The

with a heat responsive element I88 within the plenum chamber, atransformer I10 for supplying current to the ignition electrodes I24 and a protecto relay switch I12 having a thermostaticelement I14 within the pipe I58 and subject to the temperature of the exhaust gases. A diagram of a possible wiring circuit is illustrated in Fig. '1 and operates as follows: Current is supplied to the terminal box I84 by means of the power circuit from the house I15. From the terminal box the circuit extends through the limit switch I88 to the transformer I10 which provides currentto the electrodes I24. After passing the transformer I10, the current is supplied to the protecto relay switch I12 which is a manual control for turning the circuit on or off and also includes a delayed action circuit controlled by the thermostatic device I14. When the switch I12 is turned on, and after a definite time, if the temperature-around the thermostatic device I14 has not risen to a predetermined figure due to the passage of burning gases therearound, the thermostatic switch I14 will reopen the motor circuit thus'causlng the how of air and oil to the This is a safety feature in that aperson can not turn on the furnace and go away and leave it running without flames starting. The furnace can not be filled with 9. dangerous mixture of oil and air which might later explode. The limit switch I88 operates to shut off the motor and furnace operation should the temperature in the chamber rise too high as would be the case if the fan belt driving the circulating fan 20 were to break. It should be obvious that the controls for the furnace may be rearranged to suit most any operating condition and may include a thermostat in the space being heated.

damper I84 is so designed that on an increase in pressure the damper becomes unbalanced and swings to a permanently open'position indicating that the filters are clogged and should be changed.

The passage through the furnace of air being heated is indicated by the full-lined arrows and is as follows: Through the opening I2 in the top of the casing through the filters or through the by-pass damper down the side of the casing to the intake of the blower 20, then the air is forced upward inside of the-partition 48 and around the outside of the radiator. After passing around the radiator, the air passes back and around the rear end of the radiator and into the annular passage between the radiator and the combustion chamber. The air is forced through this annular passage over the humidifying pan I80 and out through the plenum chamber past the limit switch control I88.

The path .of the products of combustion is indicated by the broken line arrows and is as fol- J lows: The air is drawn in through the conical burner opening H8 and the radial openings II8 from the inside of the casing due to the suction created by the exhaust blower 22. In the burner head the. air is mixed with oil from the nozzle I22 and is ignited by the spark from the igniters I24. The resulting flame is largely confined to the space within the combustion chamber which is lined with fire bricks. From there the hot gases pass into the rear end of the combustion chamber. out through the stack 84 in the top of the combustion chamber in the radiator between the two outer cylinders. In the radiator the gases spiral around and towards the front where they pass out the opening I I2 through the pipe I58 past the thermostatic control I14 for the protecto relay, then through the pipe I54 to the duct I52 which forms the intake for the blower 22. After passing through the blower the products of combustion are blown out the pipe I58 and up the chimney.

It will be noted that with this arrangement I have provided that the flow of air being heated and the flow of the hot gases are reversed over the heating surfaces so that the difference in temperature of the two paths of gases is at a maximum at all time; thus, the air to be heated, which is coldest when it enters the furnace, is first brought in contact with the circular panel 48 which will be heated to some extent by radiation from the radiator. After the air has picked up some heat from this panel, it is brought into contact with the hotter surfaces of. theradiator and, when the air has picked up heat from the radiator and has risen to higher temperatures, it is conducted over the extremely hot surfaces of the combustion chamber within the radiator. Since the amount of heat which a fluid will pick up in passing over a heated surface depends upon the difference in temperature between the fluid and that surface, it is evident that I have provided for amaximum amount of heat transfer between the air being heated and the products of combustion.

Since the draft for drawing air into the combustion chamber and disposing of the products of combustion is maintained by the blower I50,

the furnace may be operated with practically any type of chimney. Further, the furnace may be tested and the controls adjusted at the factory by experts without having to know the type and eiiiciency of the stack to which the furnace is to be attached. This insures efficient operation' of the furnace regardless of the skill of the dealer who installs it.

While I have described my invention in some detail, I intend this description to be an example only and not limiting upon my invention which is defined in the following claims.

I claim:

1. In a warm air furnace adapted to be erected in a confined area, a substantially cylindrical combustion chamber, an annular elongated radiator, said radiator being disposed about the outer wall of said combustion chamber in spaced apart relationship thereto and forming with said combustion chamber a unit assembly, an outer furnace casing divided into two parts separable at a vertical plane substantially bisecting the casing longitudinally, and partial partition and supporting walls carried by each of said casing parts arranged so that the said walls of one said part cooperate with the said walls of the other said part to support said unit assembly substantially centrally within said casing and to provide air conducting passageways through the casing in immediate contact with the exposed walls of the combustion chamber and radiator of said unit assembly.

2. In a warm air furnace as-defined in claim 1, the disposition of the said combustion chainber and radiator unit assembly being such that its central axis is in a horizontal plane extending longitudinally of said casing and vanes within said radiator directing the flow of hot gases and products of combustion in a helical path during its passage longitudinally through the radiator.

3. In a hot air heating assembly including a housing having a cold air inlet and a hot air outlet, means in said housing defining a path of flow for air from said inlet to said outlet comprising a generally centrally positioned elongated drum-like stove, a hollow wall tubular radiator embracing said stove in spaced generally concentric relation thereto forming an air heating space therebetween, oil burning means located in a first end portion of said stove, conduit means placing the other end of said stove in communication with the adjacent end of said hollow radiator, flue defining means communicating with said radiator adjacent said oil burn; ing means for removing combustion gases, means including a blower for delivering substantially all of said cold air from said inlet first against the outside of said radiator, thence delivering all of said air around the end of said radiator remote from said oil burning means, then between said radiator and said stove, and conduit means adjacent said oil burning means for directing all of said hot air from between said radiator and said stove to said hot air outlet.

4. In a furnace including a surrounding housing provided with a cold air inlet and a hot air outlet, a stove and radiator arrangement within said housing defining an air heating space therebetween wherein the rate of heat transfer from said stove and radiator to said air is made to be substantially the same along the axial extent of said heating space, said arrangement comprising a central horizontally elongated drum-like stove, a hollow walled tubular radiator embracing said stove and spaced in generally concentric relation thereto, oil burning means located in one end of said drum-like stove, conduit means placing the other end of said stove in communication with the juxtaposed end of said hollow radiator, flue defining means communicating with said radiator at the other end thereof adjacent said oil burning means for removing coinbustion gases, means shutting off the entry of air between said radiator and said stove adjacent said oil burning means, the space between said stove and said radiators adjacent the other end thereof being open for the entry of air thereto, means including a blower for delivering cold air from said inlet first against the outside of said radiator thence around the open end of said radiator remote from said oil burning means and then between said radiator and said stove, and conduit means adjacent the other end of said space juxtaposed to said oil burning means for directing hot air from between said radiator and said stove to said hot air outlet.

MORITZ L. MUELLER.

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