US3494599A - Portable forced-air heater - Google Patents

Description

Feb. 10, 1970 J. J. STUPAK, JR., ET A 9 PORTABLE FORCED-AIR HEATER Filed Oct. 6, 19s? 3 Sheets-Sheet} IIIIIIIIIIII INVENTOR. JOS/W J 670341; gar/A50 &. Jo/vas M @g ATTOZ/WEVS Feb. 10, 1970 J. J. STUPAK, JR., ET AL PORTABLE FORCED-AIR HEATER 3 Sheets-Sheet 5 Filed Oct. 6, 1967 V, w muw m M U m H 2 W United States Patent 3,494,599 PORTABLE FORCED-AIR HEATER Joseph J. Stupak, Jr., and Howard B. Jones, Upland, Calif., assignors to Scheu Products Company, Upland, Calif., a limited partnership of California Filed Oct. 6, 1967, Ser. No. 673,469 Int. Cl. F231 9/04; F2311 /24 U.S. Cl. 263-19 8 Claims ABSTRACT OF THE DISCLOSURE This invention relates to heaters and more particularly to a relatively compact and portable forced-air heater for providing a high-heat output.

Various types of heaters and forced-air heaters have been devised in the past. Typical heaters having a highheat output have been relatively large and bulky and sometimes have lacked suitable safety features.

Accordingly, it is a principal object of this invention to provide a new portable forced-air heater.

It is an additional object of this invention to provide a compact and lightweight forced-air heater which is of relatively simple construction and which may be readily disassembled for service.

Another object of this invention is to provide a forcedair heater which is safe and reliable in operation.

A further object of this invention is to provide an improved burner assembly and control for a forced-air heater.

An additional object of this invention is to provide an improved forced-air heater which uses vapor or liquid gas.

These and other objects and features of the present invention will become better understood through a consideration of the following description taken in conjunction with the drawings in which:

FIGURE 1 is a side view of a portable heater according to the present invention;

FIGURE 2 is an inlet end view of the heater of FIG- URE 1;

FIGURE 3 is a circuit diagram of a control system for the heater;

FIGURE 4 is 'a side sectional view of the control assembly for the heater;

FIGURE 5 is a top sectional view of the control assembly of FIGURE 4;

FIGURE 6 is a cross-sectional view of a portion of the heater illustrating the placement of the burner assembly and tube liner thereof;

FIGURE 7 is a view of the burner assembly taken along a line 77 of FIGURE 6;

FIGURE 8 is a view of the burner assembly taken along a line 88 of FIGURE 6;

FIGURE 9 is a cross sectional view of a portion of the burner assembly taken along a line 99 of FIGURE 7; and

FIGURE 10 is a simplified illustration of the placement of the tip-over switches.

Among the principal features of the present invention are the construction of the present heater and the burner assembly which enable a relatively lightweight and compact heater of high-output capabilities to be provided. The

3,494,599 Patented Feb. 10, 1970 entire heater is enclosed, and several safety features are provided to insure that the heater is safe in operation. The safety features include a time delay ignition circuit to turn off the gas supply it ignition does not occur within a predetermined time, as Well as overheat and tipover controls. The heater is constructed of separable components so that the same may be disassembled relatively simply. Additionally, a liner used within the shell of the heater allows the exterior of the shell to be relatively cool even though a typical output temperature of the heater is 3400 Fahrenheit. The heater may be operated on liquid or vapor gas. A heater constructed in accordance with the teachings of the present invention may provide an adjustable burning rate of, for example, 100,000 to 350,000 B.t.u.s per hour and heat, for example, an area ten feet across at a distance of thirty to forty feet. Heaters of this nature are used for space or localized drying, crop or animal drying, deth'awing equipment, and so forth.

Turning now to the drawings, the forced-air heater of the present invention includes an outer metal tubular shell 10 within which is mounted a blower including a fan motor 11 and blade 12. Also mounted within the shell 10 is a burner assembly 13 and a liner 14. The shell 10 is mounted on a control assembly or box 15 which houses the control components for the motor and burner. An inlet grill 16 and carrying handle 17 are provided. A typical heater may be approximately 20 inches tall and 30 inches long, with the diameter of the shell 10 being approximately 13 inches. The construction of the burner assembly 13 and the gas and air paths of the burner assembly enable the heater to be shorter for a given B.t.u. output and good combustion than typical heaters of this nature.

The motor 11 is mounted within the shell 10 on a motor mounting plate 20, and the burner assembly 13 is mounted within the shell 10 on brackets 21 and secured to the top of the shell by a bolt 22. The liner 14 is mounted within the downstream end of the shell 10 by means of spacers 23 through 26 as best seen in FIGURE 7. The spacers may be spot welded or bolted between the shell and liner. The shell 10 is bolted to the top of the control box assembly 15. A control panel 30 and an access panel 31 are provided as covers for the control box assembly 15.

The burner assembly 13 includes a burner venturi mixer and burner 33 as best seen in FIGURES 6 and 7, and the same may be constructed of cast aluminum. The burner assembly also includes a flame spreader backplate 34, which may be formed of stainless steel, and a front plate 35. The .backplate 34 is mounted on a step 36 of the burner venturi 33, and the front plate 35 is spaced from the venturi by means of a plurality of spacers 37. The plates 33 and 34 and spacers 37 are secured to the burner venturi 33 by means of a plurality of bolts and nuts. A gas nozzle assembly 40, which will be explained in more detail subsequently, is secured to the bottom of the shell 10 as best seen in FIGURES 4 and 6 by means of a support bracket 41 and supplies gas to the throat 42 of the burner venturi 33. The throat 42 is restricted at 43, and a typical diameter at the restriction is one inch. The venturi includes a chamber in the form of an elbow which flares slightly upstream of the throat such that the outlet 44 thereof has a slightly greater diameter, such as one and one-eighth inch. An igniter, such as a spark plug 45 is provided to ignite the gas and air mixture emanating from the outlet of the burner venturi. The primary air for combustion is derived from air blown by the blower which enters the throat 42 along with gas from the nozzle assembly 40.

The flame spreader backplate 34 is cupshaped and has a plurality of holes therein through which air from the blower may pass and mix with the air/ gas mixture from he burner venturi. This is secondary air to complete comustion. The flame normally commences between the ront and backplates a fraction of an inch from the peiphery of the front plate, and this is a function of gas rressure and velocity. The backplate 34 has, for example, hree rows of sixteen holes each as shown in FIGURES and 8. The inner row of holes may be on a radius of 2 /2 nches, the next row of holes on a radius of 3% inches, vnd the outer row of holes on a radius of 3 inches. Each of the holes typically may be inch in diameter, nd adjacent holes are spaced apart 11% degrees. It will he apparent that the air supply for combustion is forced vith the principal mixing occurring in the burner venturi :hamber. The burner arrangement illustrated enables the hell 10 to be shorter than usual while still providing a nigh B.t.u. output and good combustion. The liner 14 acts .s a reflector to maintain the shell 10 cool. Inasmuch as here is an annular forced air space about the liner 14, teat absorbed by the liner is removed by the flowing air tream.

Turning now to the control box assembly 15, the same iouses the control components for the present forced-air leater. A gas inlet 50 is coupled with a solenoid valve 51 vhich is coupled through a nipple 52 to a pressure regllator 53. The inlet 50 and solenoid valve 51 may be se- :ured to the control panel 30. The pressure regulator 53 ncludes a control knob 54 for setting the inlet pressure the heater. The outlet of the pressure regulator 53 is :oupled through a T connector 55 and through a line 56 o a pressure gauge 57. The outlet also is coupled through L line 58, a connector 59 and a connection line 60 to the 102216 assembly 40. The line 60 is coupled by means of L nut 62 and an adapter 63, of the nozzle assembly 40 to he nozzle 64. The nozzle 64 is secured to the bracket 41 )y a nut 65. An aperture 66 is provided in the bottom of he shell 10 to allow the gas from the nozzle 64 to flow o the throat 42 of the burner venturi 33. If it is desired 0 use liquid gas, a liquid vaporizer loop (not shown) is wed in place of the connection line 60. The vaporized oop may be, for example, approximately a two-foot ength of tubing which extends from the connector 59 to he nozzle assembly 40, but which extends up into the .hell 10 adjacent the burner assembly 13 to enable vaporzation of the liquid gas. For moderate flow rates and nornal temperatures, vapor gas is used in conjunction with a gaseous withdrawal tank. In very cold weather or when a ery high flow rate is desired to provide a high-heat outiut, the vaporizer loop is used along with a liquid withlrawal tank. If desired, several vapor tanks may be ganged together to provide sufiicient gas to operate with he connection line 60 where a high-heat output is reruired.

The control box assembly 15 also houses electrical components for controlling the heater. These components are llustrated in FIGURES 4 and 5, and a circuit diagram :hereof appears in FIGURE 3. A thermostat 70 is nounted on the control panel 30 and includesa control rnob 71 and dial plate 72. A red Warning light 73 and a Iellow ignition light 74 also are mounted on the control panel 30. An igniter transformer 76, igniter control 77 and terminal strip 78 also are mounted in the control box as best seen in FIGURES 4 and 5. A flame sensor 80 s mounted within the control box 15, and this sensor in- :ludes a probe 81 extending into the shell adjacent the :op of the backplate 34 to sense the existence of a flame from the burner assembly. A tip-over switch assembly also is mounted within the control box assembly and ncludes a pair of mercury switches 84 and 85 mounted an a forty-five degree angle with respect to a vertical plane :xtending through the center of the heater as best seen i FIGURES 5 and 10. These switches are mounted upon a Jracket 86. The tip-over switch assembly serves to shut air the gas supply and igniting system if the heater is ;ipped to the side (as seen in FIGURES 2 and 10) approxmately forty-five degrees or more or tipped up on end (as seen in FIGURE 1 and FIGURE 10) approximately ninety degrees. A high temperature limit switch 88 is affixed to the upstream end of the shell 10 near the burner assembly 13. This switch serves to shut down the heater if the same overheats or if the blower fails. The wiring between the various electrical components is not illustrated in FIGURES 4 and 5 so as not to unduly clutter these figures. Four feet- only feet 90, 91 and 92 being seen in the drawings-are secured to the bottom of the control box assembly 15.

Turning now to consideration of the electrical control system and operation of the heater, a circuit diagram of the control system is illustrated in FIGURE 3. An input two conductor A.C. line 95 supplies power to the control circuit, and one conductor 96 is coupledthrough a fuse 97 to the thermostat 70, and the other conductor 98 is a common line. The red lamp 73 is connected across the input supply, and the blower motor 11 is coupled between the output of the thermostat 70 and the conductor 98. The thermostat 70 is coupled through the tip-over mercury switches 84 and 85 to the ignitor control 77. The ignitor control 77 includes a resistive heater 99 coupled in series with a relay coil 100 and the flame detector switch 80. The heater 99 operates a safety switch 101 after a predetermined delay, such as forty-five seconds. The relay coil 100 operates a switch 102 which is coupled with a solenoid 103 of the solenoid gas valve 51. The solenoid 103 in turn is connected through the high limit switch 88 back to the conductor 98. A resistance 104 is coupled across the switch 102. The yellow lamp 74 and the primary 104 of the ignitor transformer 76 are coupled across the output of the ignition control 77. The secondary 105 of the transformer 76 is coupled with the spark plug 45. The resistance 104 is a holding resistance and has a value high enough so as not to allow operation of the solenoid valve 51 unless the switch 102 is closed. However, once the switch 102 closes to energize the solenoid 103, this switch may open and sufiicient current flows through the resistance 104 to hold the solenoid valve 51 open. If the switch opens, either switch 84 or opens, or the supply voltage drops too low the solenoid valve 51 closes and cannot reopen until the switch 102 is caused to reclose.

With power supplied to the input line and gas sup plied to the gas inlet 50, the red lamp is on serving as a warning that the heater may operate automatically at any time. The knob 71 of the thermostat 70 is rotated to close the contacts thereof which cause the blower motor 11 to turn on. If one of the safety devices, e.g., the tip-over switches, has not been activated, the ignition cycle begins. The yellow lamp 74 is on during the ignition cycle. Current is supplied through the tip-over switches 84 and 85 and the safety switch 101 as well as the flame detector switch 80 to the ignition transformer 76 thereby activating the spark plug 45. Current also is supplied through the resistance heater 99 to energize the relay coil which in turn closes the switch 102 to energize the solenoid 103 and open the gas valve 51. Gas is then supplied to the nozzle assembly 40, and the spark plug 45 causes ignition at the burner assembly. After the time delay of the heater 99 and safety switch 101, the ignition control 77 turns off. If the burner flame is too small or if the burner does not ignite, the flame sensor switch 80 does not open. If this occurs, the gas valve will be closed at the end of the delay provided by the ignition control. Thus, if everything is operating properly the spark plug 45 ignites the gas and when the flame is sensed by the flame detector the switch 80 thereof turns off the ignition control 77. If ignition is not accomplished within the delay period, the switch 101 opens thereby deenergizing the solenoid 103 and the ignition transformer 76. If this occurs, the heater may be manually turned off several minutes thereby allowing the switch 101 to again close and the foregoing cycle be repeated. Also, the heater should be checked and any malfunction, i.e., tipped over, should be corrected.

If the heater is tipped to either side approximately forty-five degrees, or tipped on end approximately ninety degrees, one of the mercury switches 84 or 85 will open and turn oif power to the ignitor control 77 and solenoid 103 of the valve 51. The blower motor 11 will continue to run in order to cool the heatenas quickly as possible. 'In the event the heater over heats, the high limit switch 88 senses this condition and turns ofl? power to the solenoid 103. After this switch 88 and the flame detector switch 80 close, the ignition cycle will be repeated. Such excessive temperature will occur if the inlet air or exhaust is blocked to the extent that burning is hampered thereby producing carbon monoxide, or if the blower motor 11 or the pressure regulator 53 supplies excessive gas. The pressure rating of the solenoid valve may be selected at a maximum value, such as 135 p.s.i., at which it will not open to prevent rupture of the pressure regulator. -Excessive inlet pressure may occur if the heater is misconnected in some manner. Usually, a regulator preset at a given pressure, such as 40 p.s.i., at the supply tank (not shown) will limit the pressure to the heater.

if there is a power failure or the voltage drops too low, the solenoid valve 103 will cause the gas to be turned ofl. If the gas supply fails, no dangerous situation is present but the heater will attempt to reignite. If, after the time delay of the ignition control no flame is established, the heater will turn off and will not restart until turned off manually for several minutes to allow the switch 101 to close. The same occurs if the gas pressure becomes too low. If desired, a switch may be provided to turn off the entire heater if the power supply voltage drops below a predetermined level.

In operating the heater, a vapor or liquid gas supply tank (not shown) is coupled with the inlet 50. With the gas supply tank turned off and the thermostat 70 turned off, the powerline 95 is connected with the power supply. The valve on the tank is opened and the thermostat knob 71 is rotated to a full on position. The heater automatically ignites, and then the pressure regulator control knob 54 may be adjusted to obtain the desired B.t.u. output. The thermostat is then set to the desired temperature, and the heater turns on and off automatically as the temperature varies. The heater is turned off by closing the valve to the gas tank, and then allowing the heater to continue to operate until all remaining fuel in the lines has been burned. The thermostat is then turned off. In the event the heater automatically turns off because of an emergency condition, e.g., has been tipped over, the thermostat is turned off and the cause of the automatic shutoff is corrected. After several minutes, the heater may be restarted according to the foregoing procedure.

The present embodiments of this invention are 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 therefore are intended to be embraced therein.

What is claimed is:

1. A burner assembly for a forced-air heater having a shell through which air is forced, said assembly comprisventuri mixer and burner means having an inlet end in the form of a substantially conical throat within and spaced from said shell for receiving gas and forced arr,

said mixer and burner means having a chamber therethrough for receiving forced air and gas and for mixing and supplying the same to the outlet of said chamber, said chamber outlet being slightly flared outwardly upstream of said throat,

first spreader plate means being mounted on said mixer and burner means and extending generally laterally from said outlet, said first plate means having apertures therein through which additional forced air may flow and mix with said air and mas mixture to complete combustion thereof, and

second plate means mounted on said mixer and burner means adjacent to but spaced from and laterally across the outlet of said chamber for deflecting the mixture flowing from said chamber to flow generally laterally along said first plate.

2. A burner assembly as in claim 1 wherein said first plate means is cup-shaped having apertures in the base thereof, and said second plate means is a solid circular plate mounted within the cup of said first plate, and

ignition means mounted on said mixer and burner means adjacent the outlet of said chamber for igniting the mixture flowing therefrom. 3. A control system for a forced-air heater employing a blower motor for forcing air past a burner, and a solenoid operated gas valve for supplying gas to said burner, comprising input power supply lines, one of said power supply lines being coupled through a thermostat to an output terminal thereof which in turn is coupled with said blower motor, and the other of said powerlines being a common line coupled to said motor,

tip-over switch means for causing said solenoid valve to be de-energized upon the occurrence of a predeter mined event, flame detector means for detecting a predetermined flame temperature in the vicinity of said burner,

ignition control means, said ignition control means including a pair of input terminals, a first of which is coupled through said tip-over switch means with the output terminal of said thermostat, and the second of which is coupled through said flame detector switch means to said common power line, said ignition control means including first and second output terminals, said solenoid valve being coupled in series with limit switch means between said first output terminal of said ignition control means and said common power supply line, and

igniting means for supplying igniting energy to said gas, said igniting means being coupled between the second output terminal of said ignition control means and to the second input terminal of said ignition control means, said ignition control means including delay means for supplying igniting energy to said gas and for terminating said igniting energy if ignition of said gas does not occur within a predetermined time period.

4. A forced-air heater comprising shell means having blower means mounted therein for forcing air through said shell means, said shell means having a longitudinal axis,

burner means mounted within said shell means, said burner means serving to receive an air-gas mixture which is burned,

control means coupled with said burner means for con trolling the operation thereof, said control means including a gas valve for supplying gas to said burner means and including igniting means for igniting the gas and air mixture from said burner means, and tip-over switch means coupled to said control means for controlling the operation of said gas valve and terminating gas supply to said burner means in the event said heater is rotated about said longitudinal axis of said shell means a predetermined amount or said longitudinal axis of said shell means is tipped a predetermined amount from horizontal, said tipover switch means comprising a pair of electrical switches each having a movable electrical conductor therein responsive to movement of said switches, said switches being coupled with said shell means and being mounted at an angle with respect to each other. 5. A heater as in claim 4 wherein said switches are mounted each approximately at a forty-five degree angle with respect to a vertical plane extending through said longitudinal axis of said shell means.

6. A portable forced-air heater comprising shell means having blower means mounted therein for forcing air through said shell means,

burner means mounted within said shell means, said burner means serving to receve an air-gas mixture which is burned,

a solenoid gas valve coupled with said burner means for supplying gas to said burner means,

igniting means for'igniting the gas-air mixture from said burner means, i

ignitioncontrolmeans coupled with said solenoid gas valve and said igniting means for controlling the operation thereof, said 1 ignition control means .including an electricaldelay circuit for supplying ignit ing energy to said ignition means and for terminating said igniting energy if'ignition of said air-gas mixture does not occur within a predetermined time period; said electrical delay circuit including a safety switch coupled between a source of electrical energy and said ignition means, and including a delay device coupled with said safety switch for opening said switch after a predetermined period of time;

said ignition means including a relay operated switch coupled in series with said solenoid gas valve and including a relay winding for operating said relay operated switch coupled in series with said delay device;

a flame sensor switch coupled in series with said relay winding and delay device, said relay operated switch and solenoid gas valve being coupled in parallel with the series connection of said flame sensor switch, relay 'winding and delay device; and

tip-overiswitch means coupled'in series between said safety switchand said source of electrical energy, said tip-over switch means comprising a pair of electrical switches each having a movable electrical conductor therein responsive to movement of said switches, said switches being coupled with said shell means and being mounted at an angle with respect to each other.

7. A heater as in claim 6 wherein said burner means has an inlet spaced from said shell means for receiving air from said blower means and for receiving gas, said burner means including a chamber there-through from said inlet to an outlet for mixing gas from a gas nozzle spaced from and communicating with the inlet of said chamber and air from said blower means and supplying the mixture to said outlet, first and second spreader plate means being mounted on'said burner means, oneof said plate means having a plurality of apertures therein through which additional air from said blower shell means having blower means mounted therein for forcing air through said shell means, t burner means mounted within said shell means, said burner means serving to receive an air-gas mixture which is burned, v a solenoid gas valve coupled with said burner means for supplying gas to said burner means, 7 1 igniting means for igniting the gas-air mixture from said burner means, 7 a flame sensor switch mounted near said burner means for. sensing the heat therefrom, said sensor switch being coupled to control'said igniting means and turn off the same whena predetermined flame emanates from said burner means,

ignition control means coupled with said solenoid gas valve and said igniting means for turning on said valve and supplying electrical energy to said igniting means for a predetermined period of time, said ignition control means including a safety switch coupled with said igniting means for turning off said igniting means after a predetermined period of time in the event the igniting means is not turned off by said flame sensor switch; and

tip-over switch means coupled to said ignition control means to terminate the supply of electricalenergy thereto in the event said heateris tipped a predetermined amount, said tip-over switch means comprising a pair of electrical switches each having a movable electrical conductor therein responsive to movement of said switches, said switches being coupled with said shell means and being mounted at an angle 1 with respect to a vertical plane extending through the longitudinal axis of said shell means.

References Cited UNITED STATES PATENTS 3,050,111 8/1962 Hubbard et a1 431-243 3,338,287 8/1967 Clark 43171 3,114,538 12/1963 Kennedy.

3,126,198 3/1964 Wise. 3,210,059 10/ 1965 Nesbitt et al.

3,306,335 2/1967 Myers.

3,314,411 4/ 1967 Power 12685 3,319,947 5/1967 Truesdell.

EDWARD G. FAVORS, Primary Examiner US. Cl. X.R.

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