US2015251A

US2015251A - Space heater

Info

Publication number: US2015251A
Application number: US715111A
Authority: US
Inventors: Browning George
Original assignee: Chicago Flexible Shaft Co
Current assignee: Chicago Flexible Shaft Co
Priority date: 1934-03-12
Filing date: 1934-03-12
Publication date: 1935-09-24
Anticipated expiration: 1952-09-24

Description

sept. 24, l1935.

G. BRowNlNG SPACE HEATER Filed March 12, 1954 2 Sheets-Sheet 1 JMW j; W M7' 9% Sept. 24, 1935. G, BRowNlNG SPACE HEATER Filed March 12', 1954 f 2 Sheets-Sheet 2 Patented Sept. 24,1935

SPACE HEATER. George Browning, Wilmette, Ill., assignor to Chicago AFlexible Shaft Company,

corporation of Illinois Chicago, Ill., a

Application March 12, 1934, Serial No. 715,111

4 Claims. (Cl. 21S-39) e 'This invention relates to space heaters and has special reference to heaters of the type wherein the heat from an electric coil or heating element is distributed by means of a fan.

Heaters of the type mentioned are usually constructed to carry relatively high wattage, commonly in the region of 1200 watts and higher.- The coils are enclosed in a protective case and a fan is mounted in the case to draw air into the case and discharge it across the coils. The temperature of the casing'is held down by the rapid and forced circulation of air through the heater. In the absence of this forced draft, the large amount of heat thrown off by the coils rapidly brings the casing to a dangerously high temperature. It is particularly important that this should not occur because a-large use for heaters of this type is in the care of children where the heaters are used to heat the rooms a little beyond their normal temperature'for the childrens baths and the like". Heaters of this type may, therefore, be dangerous should the forced draft be cut off by stoppage of the fan. Another objection to heaters of this character which is augmented by the nature of their use is the fact that the "heaters are readily portable and may be easily moved about or tipped overand consequently may be moved by children into close proximity to walls and the like, or may be. tipped over so that the face of the heater lies against the table, whereupon there is danger of re should the heater continue to run in its normal way.

A primary purpose of this invention is the provision of a space heater embodying safety means to prevent the casing from becoming excessively hot.

Another object of the invention is to provide a space heater wherein the supply of current is terminated when the heater is placed in such position'as to prevent the substantially free dissipation of the heat whereby to prevent reor excessive accidental damage.

A further object of the invention is to provide a generally improved heater of a construction lsuch as to substantially minimize the danger of fire damage and accidental injury to the operator or to children.

A further object of the invention is to provide a space heater embodying combined safety means to prevent the heater from becoming excessively hot because of the stoppage of the fan, or otherwise, and to cut off the power supply in the case of overheating.

Other objects and attendant advantages will become apparent to those skilled in the art from drawings, in which- Figure l is a vertical section through the heater taken at right angles to theface;

Fig. 2 is a face viewv ofthe fuse assembly;

Fig. 3 is atop view of the fuse assembly;

Fig. 4 is a section on the line 4-4 of Fig. 2;

Fig. 5 is a sectionon thel line 5 5 of Fig. 2;

Fig. 6 is a vertical section through the heater taken at right angles to Figure l, and 10 Fig. 7 is awiring diagram of the heater.

The embodiment of the invention herein illustrated contemplatesa casing designated generally by the numeral 8 having a base designated generally by the numeral 9 to which feet II are aia-"i5 tached for the purpose of supporting the casing, the feet preferably being of some resilient material, such as rubber, to protect the finish of tables or other furniture upon which the heater may be placed. The base 9 has a tcp surface l2 which 20 forms the bottom of the heater chamber designated generally by the numer-al I3. The casing in this instance has imperforate side Walls i4, a

' front l5 provided with an opening I6, and a back i1 provided with a plurality of parallely disposed 25 horizontally extending louvers I8. A grill, designated generally by the numeral I9,- is positioned in the opening I6 in the front of the casing and consists of a cylindrical portion 2l adapted to rest directly in the opening I6, a front grid portion 22 30 having vertically disposed slots or openings 23 through which the air is discharged from the casing, and a laterally extending annular flange 24 attached to the inside surf-ace of the front I5 by means of screws 25 spaced from the front by 35 means cf spacers 26. Arcuate insulators 21 and \28 are positioned against 'the flange 24 at the 'top and bottom thereof, respectively, by means of bolts 29. Wire coils 3I-38, inclusive, are trained on the

insulators

21 and 28, the coils 40 3 l-34 forming one unit of the heater coil and the coils 35-38 forming a second unit, the two units being divided substantially at the center of the

insulators

21 and 28.

Brackets 39 and 4I arepositioned on the insu- 45 lator 21 substantially at the center thereof and on opposite sides of the vertical center line of the casing, as shown in Fig. 6. The brackets are secured to the insulator 21 by means of bolts and

nuts

42 and 43, which serve as binding posts for 50 the'ends of the

coils

34 and 35, respectively. The brackets have downwardly extending

lingers

44 and 45 which are bent at right angles, as shown at 46 and 41, to provide supports for a horizontally disposed mica shelf 48. 'I'he brackets also 55 ing a fusible element l2 which extends between the brackets 42 and ll, as shown in Figs. 2 and 6, and serves to conduct current from the coil ll to the coil Il. Current is supplied to the coils through leads II and Bl, one of which passes through a conventional switch designated by the numeral il and attached to the rear surface of the front Il of the casing. This switch has a conventional lever l. which projects through an opening Il in the front of the case for actuation of the switch from the front of the heater. The back I'I of the casing carries a pair of vertically disposed ribs ll against which is supported a motor Il having a shaft Il carrying fan blades and I3 and supporting the blades behind and in close proximity to the coil. Current is supplied to the motor ll through leads 04. ,The back of the casing also carries a pair of horizontally disposed fans il projecting from the back of the casing toward the fln blades for the purpose of preventing recirculation of the air within the casing and causing substantially the full supply of air for theV fan to be drawn through the louvers Il. A handle designated generally by the numeral l is attached to the back i1 of the casing for the purpose of handling the heater.

Referring now more particularly to Figs. 2-5. inclusive, the fusible element l2 consists of a strip of fusible material extending between the brackets 42 and 4I and having its width reduced. as shown at l1 and Il, to provide a central portion weighted by means of the projection Il. The mica shelf Il is so placed that when the heater occupies its normal upright position, the molten metal resulting from fusion of the fusible element Il will drop onto the shelf and be retained thereon. This prevents the molten metal from falling onto the current carrying parts.

The composition of the fusible element l2 is such as to fuse when the temperature of the upper portion of the heater raises to a certain predetermined maximum so as to prevent the casing or heater from becoming excessively hot. While various combinations may be used, I have found that under the circumstances an alloy consisting 0f about four parts tin, four parts lead, and one part bismuth, is satisfactory.

Attention is directed to the fact that the location of the fusible element is a` matter of considerable importance to the invention since the purpose of the device is to supply heat, The parts of the heater are necessarily subjected toa certain amount of heat and it is necessary that the fusible element remain intact under the normal operating temperature of the device. However, to accomplish the purposes of the invention, the fusible element must fuse under certain definite conditions, that is, when the fan ceases to operate or when the heater is placed in such position that the heat is not rapidly dissipated. Furthermore, there must be a sumcient differential be,-

tween the normal operating temperature of the fusible element and its fusing point to insure that the fusible element does not fuse under slight abnormalities in operating conditions. In other words, for the satisfactory operation of a heater embodying a safety device of this character, there must be a comparatively wide marginal zone through which the temperature may fluctuate without, in any way. interfering with the' operation of the heater. yet the operation of the fusible element must be positive when it reaches the upper edge ofthe marginal zone. I have found that these results can be obtained by placing the fusi- 8,015,251 `carry screws. and ll for the purpose of attachble element in a position above the center portion of the coil, When placed in this position, the

' fusible element is maintained at substantially'the same temperature as the other portions ofthe heater during the normal operation thereof since 5 the forced draft carries the heat out through the front of the casing. However, when the fan ceases to operate, the heat of the coils will rise directly upwardv and be confined in the upper portion of the casing and under these circumstances, the fusible element occupies a position at substantially the hottest portion of the heater. Consequently, at this point there exists the greatest differential between the normal operating temperature and the temperature existing when the fan ceases to operate and this position of the fusible `element will consequently give the greatest margin for normal operation of the heater.

This position of the fusible element is also most eective when the heater is so placed that discharge of air through the grill I9 is prevented. This condition usually arises either through the heater being tipped over on its face or through the heater being moved up against some object, such as the wall, or some adjacent object which cuts off the discharge of air through the openings 22. Under these circumstances, the air is deected back into the heater. Here again, the warmer air will rise so that the hottest portion of the heater will be substantially at the top of the .'10 coils in which position the maximum protection will be afforded, commensurate with the wide latitude in the normal operating temperature.

While I have thus described and illustrated a specific embodiment of my invention, I am aware 3 that numerous alterations and changes may be made therein without departing from the spirit of the invention and I do not wish to be limited except as required by the prior art and the scope of the appended claims, in which- I claim:

1. The combination in a space heater of a casing having adischarge opening, a heating coil adjacent said opening, a fan for passing air over said coil and through said opening, and a fuse for conducting electric current to the coil located substantially over the center of the coil adapted to melt upon a predetermined rise in temperature.

2. 'I'he combination in a space heater of a casing having a discharge opening, a heating coil adjacent said opening, a fan for passing air over said coil and through said opening, and a fusible element for conducting electric current to the coil located substantially over the center of the coil at a point maintained at a relatively low temperature during the normal operation of the heater and at which the temperature rises sharply upon stoppage of the fan or material closing of said opening, the fusible element being of a composition to melt at a temperature above said lower temperature and substantially at said higher temperature.

3. The combination in a space heater, of a casing having a discharge opening, a heating coil adjacent said opening, a fan for passing air over 05 said coil and through said opening, and a fusible element for conducting electric current to the coil located substantially over the center of the coil of a composition to melt at a temperature above the normal operating temperature thereof and below the maximum temperature reached when the fan stops or the discharge of air through said opening is materially retarded said element having a weighted portion adapted to become severed from its support by gravity upon 7l normal operating temperature thereof and below the maximum temperature reached when the fan stops or the discharge of air through said opening is materially retarded, and means located between said fusible element and the coil for catching the molten metal from the fusion of said element.

GEORGE BROWNING.