US 3767897 A
A plug-in electric surface heating unit for use in the cooktop of an electric range. The heating unit is a metal sheathed electrical resistance heating element in spiral form with radial, outwardly directed terminal portions in closed side-by-side relation. The invention relates to a fixed mounting bracket and a movable terminal block combination that is capable of limited relative vertical movement therebetween by virtue of a flexible coupling spring joining the two members.
Description (OCR text may contain errors)
United States Patent [1 1 Prucha et a1.
[ PLUG-IN SURFACE HEATING UNIT WITH A TERMINAL BLOCK MOUNTING  Inventors: Richard V. Prucha, Louisville;
Teamus Bowling, Fern Creek, both of Ky.
 Assignee: General Electric Company,
 Filed: Dec. 4, 1972  Appl. No.: 311,630
 US. Cl 219/451, 219/447, 219/455, 219/463, 339/191 R  Int. Cl. 1-10Sb 3/68  Field of Search 219/447, 451, 455, 219/463, 467; 339/191 R  References Cited UNITED STATES PATENTS 2,457,007 12/1948 Sutherland 219/463 2,910,570 10/1959 Bremer et a1... 219/463 3,002,079 9/1961 Smith et a1 219/451 Oct. 23, 1973 3,016,444 1/1962 Jasionowski 219/451 3,174,028 3/1965 Ammerman 219/455 3,327,095 6/1967 Hanson 219/451 3,328,562 6/1967 Jasionowski.. 219/451 3,331,944 7/1967 Burger et a1. 219/455 3,346,719 10/1967 Jasionowski 219/451 3,443,064 5/1969 Meng et al 219/451 3,571,562 3/1971 Cunningham 219/451 Primary ExaminerVolodymyr Y. Mayewsky Att0meyRichard L. Caslin et al.
 ABSTRACT A plug-in electric surface heating unit for use in the cooktop of an electric range. The heating unit is a metal sheathed electrical resistance heating element in spiral form with radial, outwardly directed terminal portions in closed side-by-side relation. The invention relates to a fixed mounting bracket and a movable terminal block combination that is capable of limited relative vertical movement therebetween by virtue of a flexible coupling spring joining the two members.
' 7 Claims, 3 Drawing Figures BACKGROUND OF THE INVENTION Therepeated use of electric surface heating units formed of metal sheathed electrical resistance heating elements in open spiral form occasions the gradual accumulation of grease spatter and food spillage that passes down between the spiral coils and eventually comes to rest either on the underlying reflector pan or a bottommost pan or insulation guard that is designed to contain the soils and protect the thermal insulation that is wrapped around the baking and broiling oven located beneath the cooktop. These accumulated soils should be cleaned up periodically so that they do not become a safety hazard or begin to contaminate the kitchen. In order to clean beneath the heating unit it is first necessary to raise the unit.
In the prior art there are two main categories of movable heating units. The first category comprises hinged units which may be raised up at an angle so that the reflector pan beneath the unit may be removed and the underlying pan wiped clean. The second category of movable heating units comprises plug-in heating units having a separate terminal block mounted beneath the cooktop. The heating unit is provided with plug-in terminal portions which are insertable into sockets in the terminal block, such that a person may unplug the heating unit from the terminal block almost in the same manner as unplugging an attachment plug of an electrical cord set from a convenience outlet mounted in the wall of a room. One important advantage in a plug-in surface heating unit is that it is easy for the average user to replace the unit without the need of an appliance serviceman to rewire the heating unit into the cooktop. One criteria is that the design must be simple in operation so that anyone of ordinary inteligence may plug in the heating unit in a foolproof action so that lengthy installation instructions are not necssary.
The principal object of the present invention is to provide a plug-in electric surface heating unit with a separate terminal block that is flexibly mounted in such a manner that it is self-aligning to facilitate the ease of insertion and withdrawal of the heating unit from the terminal block.
A further object of the present invention is to provide a plug-in surface heating unit of the class described with a flexible coupling between a relatively fixed mounting bracket and a movable terminal block to promote self-alignment of the block with respect to the terminal portions of the heating unit during insertion and removal of the unit.
A further object of the present invention is to provide a plug-in surface heating unit of the class described with a flexible coupling spring joining the teminal block to the mounting bracket in combination with a lost motion fastening means to limit the relative movement between the block and the mounting bracket to prevent overstressing the spring.
SUMMARY OF THE INVENTION The present invention, in accordance with one form thereof, relates to the combination of a stationary mounting bracket and a terminal block that is loosely supported from the mounting bracket so that the block is self-aligning during insertion and removal of the terminal portions of a plug-in surface heating unit that is electrically connected therewith. There is a flexible coupling between the terminal block and the mounting bracket, as well as a lost motion fastening means joining the terminal block to the mounting bracket to permit a limited amount of relative movement therebetween.
BRIEF DESCRIPTION OF THE DRAWINGS This invention will be better understood from the following description taken in conjunction with the accompanying drawings and its scope will be pointed out in the appended claims.
FIG. 1 is a top plan view of a plug-in electric surface heating unit mounted in a cooktop and plugged into a separate terminal block and mounting bracket combination comprising the present invention, with a part of the cooktop broken away in the area over the terminal block and mounting bracket.
FIG. 2 is a fragmentary cross-sectional elevational view taken on the line 22 of FIG. 1 and showing a side view of the terminal block and mounting bracket assembly for making an electrical connection with the terminal portions of the surface heating unit.
FIG. 3 is a fragmentary cross-sectional elevational view similar to that of FIG. 2 but showing the surface heating unit moved to an inclined or elevated position for ease in removal or insertion of the terminal portions of the heating unit into the sockets of the terminal block, with particular attention given to the relative change of position of the terminal block with relation to its mounting bracket.
DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to a consideration of the drawings, and in particular to the plan view of FIG. 1, there is shown a plug-in surface heating unit 10. This heating unit comprises a metal sheathed electrical resistance heating element 12 that is of open spiral configuration of rather standard design. Notice this heating element has two terminal end portions 14 and 16 which are arranged in close side-by-side relation and extend in a radial, outward direction, as is best seen in FIG. 1. The first terminal end portion 14 extends horizontally inward toward the center of the heating unit, and then rises vertically as at 18 to the plane of the spiral configuration, and it is then wound into the first small diameter coil 20 and then spirals in a gradually increasing radius until it finishes the largest diameter coil 22 which then is turned down vertically as at 24, and then extends outward as terminal 16 in a side-by-side relationship with the first terminal 14, as is best seen in FIG. 1.
These spiral coils of the heating element 12 are relatively flexible in a vertical direction. Hence, these coils rest on a triangular framework or spider 28 of vertically arranged metal strips which has three oppositely directed arms 30, 32 and 34. The arm 30 has upward tabs 38 which grip the outer coil 22, as well as similar tabs 40 which grip the inner coil 20. The remaining coils are unattached to the spider 28 so as to allow the heating element to have a certain amount of freedom of movement due to expansion and contraction of the heating element 12 during the heating up and cooling down of the heating element.
As is conventional in this art, a decorative trim ring 44 is supported by the tips of the radial arms 30, 32 and 34 of the spider 28 so as to be joined with the heating element 12 by means of the spider. This trim ring 44 serves as a transition piece to generally bridge or close the gap btween the outer coil 22 of the heating element 12 and the downward peripheral flange 103 defining a circular opening 46 that is formed in the cooktop 48 of an electric range. Positioned beneath the heating unit 10 is a removable reflector pan 52 which is of dishedshape having a large central opening 54, and an outer horizontal flange 56 that is adapted to rest upon a recessed ledge 58 that is formed within the opening 46 at the bottom of the flange 103. Asuitable cut-out or notch 62 is formed in the reflector pan 52 for accommodating the terminal end portions 14 and 16 therethrough, as is best seen in FIGS. 1 and 3. Missing from FIG. 1 is a center medallion that is a small circular plate that fits within the center of the spider 28 and is supported therefrom so as to close some of the opening within the smallest coil 20 and preventing large objects from falling down through the spider.
The present invention is directed to a terminal block 70 and mounting bracket 72 combination which are members separate from the heating element 12 but are for making a separable electrical connection with the heating element. The terminal block 70 is a generally hollow member formed of molded ceramic insulating material that is split horizontally through the center as at 74, for ease in molding the two parts and for assembling spring contact blades 78 within separate sockets 80. Each spring contact 78 is of generally U-shape with inwardly folded reentrant ends 82 for making strong wiping contact with a generally U-shaped blade 84 that is welded or otherwise attached to the cold terminal 86 of each terminal end portion 14 and 16. Each spring contact 78 has a flat bight portion 88 with a threaded opening for receiving a terminal screw 90 therein so that a lead wire (not shown) may be attached to the spring contact 78 for wiring the terminal block in a power circuit of the cooktop. I
The mounting bracket 72 is of folded sheet metal construction that has a top wall 95 overlying the front portion of the top wall of the terminal block 70. The opposite side edges of this top wall 95 are folded down to form side walls 97, 97 which substantially overlie the front portion of the side walls of the terminal block 70 in close side-by-side relation. The front edge of the top wall 95 of the bracket is formed with an upwardly turned tab 99 which is a mounting tab that has a hole for receiving a sheet metal fastening screw 101 that extends through the hole in the tab and is threaded into an opening in the downturned flange 103 that defines the periphery of the opening 46 in the cooktop 48. This is a simplesingle screw fastening means 101 for supporting not only the mounting bracket, but in turn the terminal block 70.
Notice in FIG. 2 that the front wall 105 of the terminal block 70 stops short of the front of the mounting bracket 72. Only the front portion of the side walls 97, 97 of the mounting bracket in front of the front wall 105 is folded under as at 107 and the ends butted together to form a downwardly inclined ramp 109 which leads from the entrance to the two sockets 80, 80 that contain the spring contacts 78, 78. Moreover, the two side walls 97, 97 of the mounting bracket are extended forwardlyto form 'two resilient grounding arms 113, 113 as is best seen in FIG. 1, that serve to make engagement with a ground strap (not shown) that joins the two terminal end portions l4, 16 of the heating element 12 so as to make a grounding connection with the sheath of the heating element 12 prior to the time that the terminal end portions 14 and 16 make electrical contact with the spring contacts 78, 78 within the sockets of the terminalblock 70.
A flexible coupling means is formed between the terminal block and the mounting bracket 72 in the form of a flat strip 117 of spring material which is fastened at one end 119 to the underside of the terminal block 70 by means of a through bolt 121. The intermediate portion of the spring strip 117 is looped up over the top surface of the inclined ramp 109 and the opposite end of the spring strip is crimped to the leading edge of the ramp by folding the edge of the spring over, as at 123. This spring 117 makes a good flexible coupling between the terminal block 70 and the mounting bracket 72, but this spring needs some protection from being strained so that it will have a long life expectancy. This strain protection is provided by the through bolt 121 which extends up through a hole in the terminal block 70 within a central insulating partition that separates the two sockets 80, from each other. As is seen in FIG. 1, an elongated slot 127 is formed in the top wall of the mounting bracket 72. A short sleeve 129 is slipped down over the top of the through bolt 121 to serve as a spacer on which a nut 131 is seated. This sleeve 129 is seated on the top wall of the terminal block and it sits within the elongated slot 127. The diameter of this sleeve 129 is slightly less than the width of the slot 127 such that the relative movement between the terminal block 70 and the fixed-mounting bracket 72 is substantially limited to movement in a vertical plane that includes the vertical through bolt 121. Thus if the terminal end portions 14 and 16 of the heating element 12 were thrust into the sockets 80, 80 of the terminal block 70 with excessive force or at an odd angle the spring 117 wouldflex to accommodate this situation, and the terminal block would tend to take the position shown in FIG. 3. Eventually the sleeve 129 would engage the back end of the slot 127 as shown in FIG. 3 and further pivotal action of the terminal block 70 would be prevented.
Having described our invention of a novel and reliable flexible mounting means for the terminal block of a plug-in surface heating unit, it will be apparent to those skilled in this art that this flexibility is desirable because in order to unplug the heating element from the terminal block it is necessary to lift the far end of the heating unit out of the opening 46 in the cooktop 48. It is well that the terminal block follow this-lifting action with a pivotal action so that when a pulling force is exerted on the heating unit it will be a simple matter to separate the terminal end portions 14 and 16 from' the spring contacts 78, 78 of the terminal block. In order to insert the terminal end portions into the terminal block it is also well to be able to have the terminal end portion ride up the ramp .109 if need be, and to be guided by the pair of grounding arms 113, 113 and in so doing tilting the terminal block downwardly at'the rear so that a straight pushing force will make the electrical connection between the terminal end portions and the terminal block. Once the final connection is made the heating unit may be lowered into the normal use position as shown in FIG. 2.
Modifications of this invention will occur to those skilled in this art, therefore it is to be understood that this invention is not limited to the particular embodirnent disclosed, but that it is intended to cover all modifications and their equivalents which are within the true spirit and scope of this invention as claimed.
What is claimed as new and desired to be secured by Letters Patent of the United States is:
l. A plug-in surface heating unit comprising a metal sheathed electric heating element having an intermediate heat-generating portion providing a generally planar heating surface supported in a generally horizontal position for supporting a cooking utensil to be heated thereby, the heating element having terminal end portions for making electrical connections therewith, said terminal end portions being disposed beneath said heating surface and projecting radially outward in sideby-side relation beyond the periphery of said heating surface, a separate insulating terminal block having electrical sockets for receiving the terminal end portions of the heating element, a stationary mounting bracket adapted to be fixed to a supporting structure and flexibly coupled to the terminal block so that the terminal block is self-aligning during insertion and removal of the terminal end portions of the heating element from the said sockets, said mounting bracket including a downwardly inclined ramp located beneath the entrance to the sockets of the terminal block, and two forwardly extending grounding arms at the sides of the terminal block cooperating with the said inclined ramp to assist in guiding the terminal end portions of the heating element into the sockets of the terminal block, said flexible coupling including a coupling spring attached to the terminal block and to the mounting bracket to allow relative movement therebetween, and a lost motion fastening means joining the terminal block to the mounting bracket to restrict the amount of relative movement there-between.
2. A plug-in surface heating unit as recited in claim 1 wherein said coupling spring is a flat strip of sheet metal that is attached at one end to the bottom of the terminal block by the said fastening means and extends over the said inclined ramp and is attached at its opposite end to the ramp.
3. A plug-in surface heating unit as recited in claim 1 wherein the said lost motion fastening means comprises a through bolt that extends through both the coupling spring, the terminal block and the mounting bracket, an elongated slot formed in the mounting bracket, and a sleeve mounted on the bolt and bearing against the terminal block and positioned within the slot of the bracket, and a lock nut holding the sleeve on the bolt so that when the terminal end portions of the heating element move with respect to the mating sockets in the terminal block the block may shift automatically to accommodate the movement.
4. A plug-in surface heating unit as recited in claim 3 wherein said coupling spring is a flat strip of sheet metal with one end bearing against the underside of the terminal block and held therewith by the said through bolt, while the intermediate portion of the said spring is substantially coextensive with the top surface of the said inclined ramp and the other end of the said spring grips the leading edge of the ramp.
5. A plug-in surface heating unit comprising a metal sheathed electrical resistance heating element in spiral form with terminal portions generally beneath the heating unit and extending radially outwardly therefrom in side-by-side relation, a separate insulating terminal block having sockets for receiving the terminal portions therein; the invention comprising a stationary mounting bracket adapted to be fixed to a supporting structure and for loosely supporting the terminal block so that the block is self-aligning during insertion and removal of the terminal portions from the sockets of the block, said mounting bracket encompassing at least a portion of the top and the opposite side walls of the block as well as having a downwardly inclined ramp located beneath the entrance to the sockets and two forwardly extending grounding arms at the sides of the block for guiding the coupling movement of the terminal portions with respect to the sockets of the block, and a coupling spring attached between the terminal block and the mounting bracket to allow limited relative vertical movement therebetween, and fastening means vertically disposed between the terminal block and the mounting bracket and fixed with respect to the block, the mounting bracket including lost motion restraining means cooperating with the said fastening means to restrict the relative vertical movement between the block and the bracket.
6. A plug-in surface heating unit as recited in claim 5 wherein the said coupling spring is a flat strip of sheet material that is attached at one end to the underside of the terminal block by the said fastening means, said strip extending over the said inclined ramp and being attached thereto.
7. The plug-in surface heating unit as recited in claim 5 wherein the said fastening means comprises a through bolt that extends up through both the coupling spring, the terminal block, and the mounting bracket, said lost motion restraining means comprising an elongated slot formed in the mounting bracket for receiving the bolt loosely therein, and a spacer member seated in the slot and on the block and held in place by a nut tightened down on the bolt.