US2475180A - Electric heater - Google Patents

Description

July 5, 1949. R. l.. F11-'CH 2,475,180

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ELECTRIC HEATER Filed July 8, 1946 2 Sheets-SheerI 2 ,64k/www rcH,

INVENTOR.

Patented July 5, 1949 UNITED STATES PATENT OFFICE ELECTRIC HEATER Raymond L. Fitch, West Los Angeles, Calif., as-

signor to The Firan Co., Santa Monica, Calif., a corporation of California Application July 8, 1946, Serial No. 681,805

3 Claims.

My invention relates generally to space heaters and more particularly to electric heaters used to heat a room by both radiation and convection.

While the use of electric heaters employing resistance elements to heat a room is not new, previous heaters have generally relied on radiant heat alone and have made relatively small use of convection currents. In addition, portable heaters of this type have been of relatively light construction, mounted on small unstable bases which permitted them to fall or be knocked over very easily. If such a heater came to rest so that its beam was directed downwardly, the concentrated heat directed against the floor has been suicient to cause serious damage to rugs and occasionally start dangerous fires. As a result, while such heaters have been effective in warming objects within their beams, they have been relatively ineicient in warming the room as a whole, and have been dangerous from the standpoint of a re hazard where there has been a possibility of their being knocked over.

It is therefore a major object of my invention to provide an electric heater of simple but sturdy construction which rests rmly on a supporting surface without any tendency to fall.

Another object of my invention is to provide a heater which uses a resistance element to provide radiant heat, and is constructed to provide additional heat to the air in the room by means of convection currents.

A further object of my invention is to provide an electric heater which has a switch therein adapted to shut off power to the heater in the event it is tipped forward so as to concentrate a beam of heat onto the floor.

It is another object of my invention to provide a heater using commercially available resistance rods having a large radiating surface, used in conjunction with an improved reflector so that the housing containing the heater remains relatively cool.

These and other objects and advantages of my invention will become apparent from the following description of a preferred form thereof and from the drawings illustrating that form, in which:

Fig. 1 is a front elevational view of my improved heater;

Fig. 2 is a cross-sectional View taken at 2 2 2 in Fig. l, showing the interior construction and arrangement of parts;

Fig. 3 is a vertical sectional view of the gravity responsive switch taken at 3 3 in Fig. 2;

Fig. 4 is a cross-sectional View of the switch taken at 4 4 in Fig. 3;

Fig. 5 is a horizontal sectional view of the lower portion of the heater taken at 5 5 in Fig. 1;

Fig. 6 is a horizontal sectional view of the heater taken at 6 6 in Fig. 1; and

Fig. 7 is a fragmentary vertical view taken at I 'I in Fig. 5 showing the assembly of the lower and vertical reflector members.

Referring now to the drawings and particularly to Fig. 1, the numeral I0 indicates generally a housing having an opening lI in its forward surface which is covered by a grill I2. As seen in Figs. 5 and 6, the housing I0 includes a pair of vertically extending side members I3 and I4 which are formed as mirror images of each other, and consequently only one of the members will be described. The side member I3' is provided with an angularly positioned section I5 at its rear end which forms a portion of the rear wall of the heater, and the innermost end of this section is provided with an inwardly extending joggle or .offset portion I6 adapted to receive a back plate I'I.

At its forward end, the side member I3 is bent inwardly to provide an angularly positioned section 2li, and from this section, another angle leads to a forward wall 2l which terminates in a re-entrant portion 22. The side member I3 thus extends completely across one side of the housing I0 and a short distance across the back thereof, while at its forward end it is, in effect, provided with a corner post construction which extends from the side portion of the member to the aperture l I. By making the side member I3 of relatively heavy gauge metal, a very strong construction is provided by `the rear section I5 and the corner post construction at the forward edge. The side member I4, as previously mentioned, is formed as a mirror image of member I3, and the two members are joined together by a, forward angle member 23 and a rear angle member 24, as shown in Fig. 6. The forward angle member 23 is substantially horizontal, and one of its ends is cut at an angle to abut against the angularly positioned section 20, with the downwardly projecting leg of the angle, which is along the rear edge thereof, bent backwardly to attach to the side 4portions I3 and I4. The rear angle member 24 has its vertical leg abutting the rear section I5 of the side walls I3 and I4 and is suitably attached thereto as by spot welding; and the horizontal leg is bent downwardly to provide a surface bearing against the side members I3 and I4 to which it is likewise attached as -by spot welding. The upper portion of the re-entrant section 22 of the side members I3 and I4 is cut away to receive the forward angle member 23, and the upper portion of the joggle section IIE is similarly cut away to receive the rear angle member 24.

Within the housing Ill and near the base thereof I provide a pan member 25 extending from side member I3 to side member I4, and from the rear portion I 5 substantially to the forward surfaces 2| of the side members. The sides of the pan 25 abut the sides I3 and I4, and are provided with upwardly extending flanges 26, as shown in Fig. '7, which may be welded or otherwise securely fastened to the sides. The rear edge ofthe pan 25 is provided with an upwardly extending flange 21 which is spaced outwardly from the joggles Il,` and extends between these joggles to hold the back plate I1 in a manner hereinafter described. At its forward edge, the pan 25 is bent upwardly and then rearwardly to form a channel-likek section 28 which adds stiffness to the pan, and which acts to support various elements of the heater. The channel section 28 and the flange 21 are clearly indicated in Fig. 2 where therey is also shown a bracket member 3.0 which may be welded or otherwise suitably attached to the rear portion of pan 25. The joggle I6 and the re-entrant section 2,2 of the side members I3 and I4 are cut away to receive thepan 25, in a manner similar to that mentioned in connection with angle members 23 and 24.

The back plate I1 consists of a flat plate fitting between the joggles t6. of the side members I3 and I4, and adapted to havev its lower edge rest upon the pan 25 at the base of the upwardly extending flange` 21. The upper edge of the back plate I1 isheld in` placey by a top 3I which may be held to the housing II)l by means of screws which engage the forward and rearward angle members 2,3 and 24. It is thus seen that a very simple but ruggedly constructed housing has been provided to which access may be obtained by removing the cover 3| and then liftingy off the back plate I'I.

Within the housing |10 I provide a reflector assembly adapted to reflect the heat from the heatingl element outwardly through the opening II.. This reflectorassembly includes a lower reflector 33, a vertical reflector 34, and an upper reflector 35.. The lower reflector 33, shown in Fig. 5 includes a substantially nat horizontal portion 3.6 in the shape of a semi-circle with a groove 31 formed near its periphery and with a lip 38 extending generally forwardly and upwardly from the horizontal portion 36 to act as a guard in a` manner hereinafter described. The forward edge of. the horizontal portion 3 6 may be provided with a. bead 4U asI shown in Fig. 2 to provide a. bearing surface which may rest on the upper surface of the channel portion 28 of the pan 2.5. The bead. or groove 38 is adapted to rest on the forward end` of bracket 30, and the overall distance between. the sides ofi the horizontal portion 36 is such as to cause them to bear 4 against the re-entrant sections 22 of the side members I3 and I4 should the lower reflector 33 be urged forwardly.

The vertical reflector 34 consists of a sheet of polished metal, such as aluminum or copper, which is curved to provide a semi-circular cylindrical reecting surface with its lower edge iitting into the groove 31 where it is held in the desired shape thereby. Along its forward edges, the reflector 34 is provided with outwardly extending flanges 4I which are adapted to nt in flange receiving members 42 attached to or forming part of the re-entrant surfaces 22. The vertical reflector 34 is held against movement by the groove 31 and the flange receiving members 42 so that it is firmly anchored in position, and aids in holding the lower reflector 33 in its desired position.

The upper reflector 35 is similar in most respects to the lower reflector 33 but consists solely of a horizontal portion having an upwardly extending ange 43 adapted to bear against the inner surface of the vertical edge of angle member 23. The reflector 35 is likewise provided with a groove 44, shaped similarly to the groove 31 of the lower reflector 33, and this groove receives the upper edge of the vertical reflector 34 to aid in holding the latter in the desired' shape, while being supported by it. To insure that the members maintain their proper relationship, a spring member 45 is attached to the top 3| and bears against the upper surface of the reflector 35 to urge it, the vertical reflector 34, and the lower reflector 33 downwardly so that the latter bears r against the channel section 28 of. the pan 25 and the bracket 30, thereby rigidly holding all members in proper alignment. While other materials may be used for the reflectors 33, 34 and 35, I have found that polished aluminum is a very satisfactory material since it is a good reflector of heat and is easily formed to the desired shape. If desired, the vertical reflector 34 may be combined with one or both of the horizontal reflectors 33 and 35 by drawing or forming them in a metal forming die.

I have found that resistance rods of carbide compounds or other suitable material are very satisfactory as heat producing elements, and since these rods are readily available, I prefer to use one as my heating element, though other resistance elements may obviously be used, To support the rod, I mount av bushing type insulator 50 in the upper reflector 35 and provide a similar insulator 5I in the lower reflector 33. These insulators 5I] and 5I are preferably located with respect to the vertical reflector 34 so that a heat beam` of the desired characteristics will be emitted from the heater. I have found that by making the vertical reector 34 in the shape of a semicircular cylinder, and locating the heating element so that it is parallelto the axis of the. cylinder centrally spaced on. a chord parallel to the reflector opening at a distance of W17 of the radius from the center of curvature very satisfactory results are obtained. With a cylinder 41A; inch radius, the center of the heater element is 2 inches from the reflector; and a` beam of heat is provided which is approximately wide, as compared with a beam of approximately 415 with previous heaters.

The lower end of the conductor which extends through the insulator 5,0 is connected to a spring member 52 which is preferably formed of a strip of metal such as phosphor-bronze or beryllimncopper bent in the shape of a U and plated with cadmium, zinc, or other suitable metal to reduce electrolytic action. The upper arm of the U-shaped spring member 52 is attached to the connector extending through the bushing insulator 50, and the lower arm has a circular disc 53 of polished aluminum or other suitable material attached to it to act as a guard member. Concentric with the guard member 53 is a cup member 54 mounted on the lower side thereof, having a central recess adapted to receive one end of a resistance rod 55. A similar assembly including a spring 56, a guard 51, and a cup member 58 is mounted on the connector extending through the lower bushing insulator 5l, and the rod 55 is thus spring mounted in a vertical position within the cavity formed by the reflecting surfaces 33, 34, and 35.

The function of the guards 53 and 51 is to reflect heat radiated from the rod 55 away from the bushing insulators 58 and 5I, and from the springs 52 and 56. In this way, the possibility of cracking of the insulators is greatly reduced and the resilience of the springs is maintained over an extended period of time. As a further aid in cooling the bushing 5I and to assist in establishing convection currents through the heater, a pair of louvered apertures 6| is formed in the lower reflector 33, and a hole or series of holes 62 is formed in the pan 25 as to permit air to enter the base of the heater and pass upwardly through the louvered opening 6I into the reector cavity. Additional holes, not shown, are formed in the bach plate l1 near the upper edge thereof to permit an additional flow of air through the heater to aid in cooling the latter and warming the air in the room.

Since the rod 55 is somewhat fragile, it is to be expected that the rod will sometimes break, and the pieces thereof might fall out of the heater. Should this breakage occur while the heater is in operation, the hot portions of the rod would constitute a serious nre hazard if they were permitted to fall onto the floor or rug on or near which the heater is resting. Iowever, by providing the upwardly and forwardly extending lip 38 at the forward edge of the lower reflector 33, all such portions of the rod 55 will be caught and retained within the reflector cavity where they will do no har When the rod 55 is to be replaced, it is a simple matter to separate the cup members 54 y and 53 a slight amount, remove the old rod, and insert a new one in its place. The spring members 52 and 56 insure that good electrical contact will be made to each end of the rod 55, and no special tools or experience are needed to effect the replacement.

In order to provide an exceptionally safe heater, I include within the housing Il) a gravity responsive switch 65 adapted to disconnect the resistance rod 55 from the power circuit should the heater be tipped forward an amount sumcient to direct most of the heat onto the hoor where it might cause serious damage. As shown in Figs. 3 and 4, the switch 65 includes a weight 66 pendulously mounted on a shaft 61 and having an insulated operating arm 68 at the upper end thereof. The shaft 61 is journalled into a pair of brackets 18 which may be attached to the rear angle member 24, and a piece of insulating material 1I such as hard rubber, a phenolic resin, or other suitable material is attached to the brackets so that the insulator is parallel to the axis of the shaft 51. Mounted on the insulator 1l is a contact point 12 connected by a conductor 13 to a terminal 14. A cooperating contact point 15 is breaking position.

mounted on a spring type conductor 16 which connects to a terminal 11, and the contacts 12 and 15 are arranged so that they are normally urged apart by the action of the spring conductor 16, but may be caused to bear against each other and Vcomplete a circuit from terminal 11 to terminal 14. When the pendulous weight 66 is in a vertical position and the housing I0 is in its normal upright position, operating arm 68 bears against the spring connector 16 to force contact 15 against contact 12 to complete the circuit as previously mentioned. However, should the heater be tipped forwardly so that the pendulous weight 66 moves with respect to housing I0 to assume the position shown in dotted outline in Fig. 4, the operating arm 58 will be moved away from contact 12, and contact point 15 will be separated from contact 12 by the urging of spring 16 to interrupt the circuit. it will be apparent, of course, that commercially available switches, such as snap-action limit switches, may be used in place of contacts 12 and 15, or a mercury switch may be used instead of the pendulous weight and switch combination herein disclosed.

The gravity responsive switch just described provides a convenient means for manually turning the heater off and on and to do this, I prefer to use a pivotecl member which is adapted to move the pendulous weight to circuit breaking position. As shown in Figs. 3 and 4, the member il@ comprises a handle portion 8l which extends through a hole 82 in the back plate I1, and which has an operating arm 83 on its inner end. The operating arm 83 is so located that when the handie 3l is in its upper limiting position, shown in solid outline, the pendulous weight 66 is free to assume its usual positions; but when the handle is in its lower limiting position, shown in phantom outline, the pendulous weight is urged to circuit An escutcheon plate 84 is mounted on the back plate I1, and has a hole 85 therein, aligned with hole 82, through which the handle 8l may extend. Preferably, the escutcheon plate 84 is provided with the legends On and Oif, corresponding to the conditions of the heater circuit with the handle adjacent the appropriate marking; and any other desired information may also be shown on the plate.

Laterally outward from the hole 82, the back plate l1 is depressed to form a pair of receiving grooves 86, shown in Fig. 4, which receive and hold a pair of ears 81 extending outwardly from handle 8l. The ears 81 are formed so that they bear against the grooves 86 and the inner surface 4of the escut-cheon plate 84, and the natural resilience of the latter provides an operation similar to an over-center spring, thereby urging the handle 8l to either its upper or its lower limiting position. The ears 81 also act to furnish pivotal support for the member 80, and thus a simple but sturdy construction is provided.

Connection to the resistance rod 55 may be made through a pin type connector plug 90 mounted on the bracket 30, with a conductor 9| leading from one terminal of the plug to the bushing type insulator 5I. The other terminal of the plug is connected through a conductor 92 to terminal 11 of switch 65, from whence the circuit is completed by conductor 93 which connects terminal 14 to the conductor extending through the bushing type insulator 50. If desired, of course, the plug `connector 96 may be omitted and the usual connecting cord supplied, having the customary plug on its end adapted to t into the usual outlet socket. Connections are then 7 made in the same manner, with the exception that the plug connector 90 is eliminated.

To complete the heater, the grill I2 is mounted in front of aperture I'l by means of lugs on the horizontal portions of the grill which are fitted into holes (not shown) in the reentrant members 22 of the sides I3 and I4. By forcing the ends of the horizontal members of the grill I2 toward each other, they may be disengaged from their receiving holes and the entire grill pivoted to permit the easy replaceemnt of the resistance rod 55.

It is thus seen that I have provided an improved heater which, while formed of relatively light material, makes use of the columnar strength of a formed sheet member to provide a very strong and rugged cabinet of great stability. Furthermore, the cabinet which I form from these members is readily assembled from simple, standard structural shapes with relatively few welded connections, and the remainder of the cabinet members and the reflector surfaces are held in position by the action of one member on another, the nal holding being accomplished by the top which is secured in place by four screws. By removing these four screws, access may be secured to the entire interior of the cabinet, and by loosening the conductors therein, all portions of the reflector assembly and the heating element may be removed without further use of tools.

In addition to the strong and rigid assembly provided by my particular form of construction, the heater has safety features which have been lacking in previously available radiant heaters. The upwardly extending lip or baille, formed as a continuation of the lower reflecting surface, prevents direct radiation of heat onto the floor near the heater and also acts to prevent glowing vportions of the resistance rod from falling onto the floor should the rod break while the heater is in use. The provision of the safety switch prevents the operation of the heater when it is tipped forward, and thus there is no possibility of the heater being operated While it is lying face downward and capable of directing such a quantity of heat to the floor or rug as to burn the latter. The resistance element provides a beam of heat which is rich in infra-red radiation, and the construction of the heater is such that it promotes a circulation of air through and around the heater to cool the latter while the air itself is being warmed.

While I have shown and described a preferred form of my invention, it is obvious that changes may be made therein and I do not wish to be limited to the particular form or arrangement of parts herein described and shown, except as covered by my claims.

I claim:

l. A portable electric heater which includes: a pair of vertically extending side walls formed of sheet metal; cross members connecting said side walls together; a back plate adapted to be supported by one of said cross members; a top removably held to one of said cross members; a lower reflector supported by one of said cross members; a vertical reflector resting on said lower reflector; an upper reflector resting on said vertical reflector; resilient means extending between said top and said upper reflector to urge the latter against said vertical reflector, said vertical reflector against said lower reflector, and said lower reflector against said cross member to hold all said reflectors in alignment; and

means for mounting a resistance element in front of said vertical member.

2. A portable electric heater which includes: a pair of vertically extending sheet metal side walls having front and rear flanges forming columnar sections; a lower cross member connecting said side walls together; an upper cross member connecting said side walls together, said side Walls being spaced apart, and said upper and lower cross members being vertically separated to form a housing having a front and a rear aperture therein; a top removably held to said upper cross member; a back plate adapted to be supported by said lower cross member to close said rear aperture, said back plate being engaged and held in place by said top; a lower reflector having a groove formed in its upper surface; said reflector being supported by said low-er cross member; a vertical reflector adapted to t within said groove in said lower reflector and be supported thereby, said vertical reflector being substantially aligned with said front aperture to reflect outwardly therefrom; an upper reflector having a groove formed in its lower surface to receive said vertical reflector; spring means attached to said top and bearing against said upper reflector to urge it, said vertical reflector, and said lower reflector downwardly, whereby said reflectors are securely held in position; a forwardly and upwardly projecting lip extending from the forward edge of said lower reflector; and resilient means adapted to support a resistance element within said housing between said vertical reflector and said front aperture.

3. A portable electric heater which includes: a pair of vertically extending sheet metal side walls having front and rear flanges forming columnar sections; a lower cross member connecting said side walls together; an upper cross member connecting said side walls together, said side walls being spaced apart, and said upper and lower cross members being vertically separated to form a housing having a front and a rear aperture therein; a top removably held to said upper cross member; a back plate adapted to be supported by said lower cross member to close said rear aperture, said back plate being engaged and held in place by said top; a lower reflector having a groove formed in its upper surface, said reflector being supported by said lower cross member; a vertical reflector adapted to fit within said groove in said lower reflector and be supported thereby, said vertical reflector being substantially aligned with said front aperture to reflect outwardly therefrom; an upper reflector having a groove formed in its lower surface to receive said vertical reflector; spring means attached to said top and bearing against said upper reflection to urge it, said vertical reflector, and said lower reflector downwardly, whereby said reflectors are securely held in position; a forwardly and upwardly projecting lip extending from the forward edge of said lower reflector; upper and lower terminal members adapted to receive the upper and lower ends respectively of a resistance element; upper and lower resilient members supporting said upper and lower terminal members respectively; upper and lower guard members of a heat reflecting material mounted between said terminal members and said resilient members to reduce the radiated heat reaching said resilient members; upper and lower insulators supporting said upper and lower resilient members respectively, said insulators being mounted in said upper and lower reflectors respectively to position said resistance REFERENCES CITED The following referenices are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,445,706 Papini Feb. 20, 1923 Number Number Name Date Pfau Jan. 15, 1929 Kercher et al. Mar. 5, 1929 Waterman Feb. 9, 1932 Shaw Aug. 23, 1932 Belcher July 16, 1935 Clemons Apr` 13, 1943 Clemons Sept. 14, 1943 Marr Aug. 12, 1947 FOREIGN PATENTS Country Date France Apr. 21, 1921

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