US 3144545 A
Description (OCR text may contain errors)
g- 11, 1954 F. E. SHRIMPLIN ETAL 3,144,545.
HEATING ASSEMBLY 2 Sheets-Sheet 1 Filed March 26, 1962 I INVENTOR.
2 IN Kiiiiii FRANK E. SHmmPuN BY and Vmem W. SWAN Hwuf. Gaul Im'd AHorna Aug. 11, 1964 F. E. SHRIMPLIN ETAL 3,144,545
HEATING ASSEMBLY 2 Sheets-Sheet 2 Filed March 26, 1962 INVENTOR. FRANK E. SHR\N\PL|N BY and VIRGIL W. SWAN 'I-lwd, em 1mm A++orneys United States Patent 3,144,545 HEATING ASSEMBLY Frank E. Shrimplin, Crawfordsville, and Virgil W. Swan,
Waynetown, Ind, assignors to Heated Concrete Products, Ind, Waynetown, Ind., a corporation of Indiana Filed Mar. 26, 1962, Ser. No. 182,366 3 Claims. (Cl. 219-213) The present invention relates to a heating assembly, and more particularly to such an assembly which comprises a rigid grille upon which is loosely woven an eleca trical resistance element, the entire assembly being adapted to be embedded in a slab of suitable material such as, for instance, any of the well known synthetic plastics which are adapted to be formed to desired shape, concrete, asphaltic materials and the like, wherein the rigid grid will effectively reinforce the slab against fracture or cracking and the electrical resistance element, when energized, will warm at least one major surface of the slab.
A primary object of the invention, then, is to provide an improved heating assembly comprising rigid reinforcement means and a heating means supported therefrom.
A further object of the invention is to provide such an assembly which shall be effective to overcome the func-' tional disadvantages of previously known devices having similar broad objectives.
A further object of the invention is to minimize the cost of such a heating assembly, while providing for substantially uniform distribution of heat over a major surface of a slab in which such an assembly is embedded.
Still further objects of the invention will appear as the description proceeds. To the accomplishment of the above and related objects, our invention may be embodied in the form illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that change may be made in the specific construction illustrated and described, so long as the scope of the appended claims is not violated.
FIG. 1 is a plan view of a preferred form of heating assembly constructed in accordance with the present invention; and FIG. 2 is a perspective view of such a heating assembly embedded in a slab.
Referring more particularly to the drawings, it will be seen that we have illustrated a grid, indicated generally by the reference numeral and consisting essentially of a plurality of longitudinally-extending, laterally-spaced, substantially parallel wires or rods 11 spanned by a plurality of transversely-extending, longitudinally-separated, substantially parallel wires or rods 12, the rods 12 being welded to the rods 11 to produce an integrated structure. It is a critical feature of the grid 10 that the individualrods or Wires 11 shall be sufiiciently stiff so that the integrated grid possesses a degree of rigidity such as to protect a slab in which it is embedded against fracture or cracking resulting from rough handling or from temperature variations. In one satisfactory form of the invention which has been successfully used in the environment for which the heating assembly has been primarily designed, the rods or wires 11 and 12 constitute low carbon steel wire, ll-gauge or heavier, the rods 11 being spaced apart by approximately one inch and the rods 12 being spaced at intervals of approximately four inches.
' In previously-known structures withwhich we are familiar, light wire mesh of the type usually referred to as chicken wire has been used to support an electrical resistance element fixedly secured to said mesh at spaced points in the length of such resistance element; and it has been found that such assemblies, when embedded in, for instance, concrete slabs, are not effective to protect ice such slabs against serious damage in use and are not effective satisfactorily to distribute a suitable amount of heat over a major surface of such slabs. We have found, however, that when a grid of the type herein disclosed, formed from rod material having a strength and stiffness at least equivalent to that of ll-gauge low carbon steel wire, is made up in the manner above described, and when a resistance element of the character to be explained is associated therewith in the relationship herein illustrated, a slab in which the assembly is embedded is effectively protected and one of its major surfaces is effectively and substantially uniformly heated upon energization of the resistance element.
As shown, such a resistance element may preferably consist of a continuous strand 13 of conventional heater wire 14 having an insulating sheath 15 thereon. The insul'ated wire is woven loosely, in the manner illustrated, among the bars of the grid in a pattern consisting of a plurality of runs extending substantially parallel with the rods 11 and joined by transverse sections, as shown, the two ends 16 and 17 of the strand 13 extending, substantially together, a significant distance away from the grid and being electrically connected to the prongs of a conventional connector plug 19. For a reason which will appear, we prefer to enclose the end portions 16 and 17 of the strand 13 in flexible, metal armor, as indicated at 18, such armor having one end disposed within the boundaries of the grid 10 and extending for a significant distance away from the grid. Preferably, an insulated ground wire 20 has one end 21 electrically connected to an element of the grid 10, extends through the armor 18 and has its opposite end 22 bared for effecting a suitable ground connection.
As has been explained, the heating assembly consisting of the grid 10 and the resistance element 13 supported thereon, is adapted to be embedded in a portable slab 23 formed of suitable, preferably monolithic material. The leads 16 and 17 and the distal end of the ground wire 20, enclosed in the armor 18, will emerge through one (preferably minor) surface 24 of the slab, a significant portion 25 of the armor being embedded in the slab, as clearly shown in FIG. 2. The heating assembly is preferably arranged in a plane parallel with the opposite, major surfaces of the slab; and it will be seen that, because of the arrangement of the resistance strand 13 upon the grid 10, the top major surface of the slab will be quite uniformly heated when the resistance element is energized.
Such a slab, with its embedded heating element, is primarily useful as a bed for animals. For instance, it has long been recognized that, particularly in the temperate zone, the most advantageous time for farrowing piglets, from the market standpoint, is also the most hazardous time, since piglets are highly susceptible, during the first few weeks of their lives, to low temperatures. The normal body temperature of a baby pig is in the neighborhood of F., and when atmospheric temperatures to which they are exposed fall below 32 F., particularly if the animals are wet, they can freeze to death in a very short time. Temperatures between 32 and 60 F. make piglets miserably uncomfortable and, particularly if they are simultaneously exposed to dampness, they are very like to contract pneumonia, influenza or other respiratory diseases which are frequently fatal. Furthermore, in seeking comfort when exposed to low temperatures, piglets will crowd and pile upon each other whereby those in the lowermost layers are frequently injured, crushed to death or suffocated.
According to the present invention, a slab having embedded therein a heating assembly of the character herein disclosed, is positioned on the floor of any suitable enclosure to provide a smooth, clean, heated surface on which the piglets may lie in complete relaxation. Because the source of heat is the floor of the pen, each piglet seeks a spot of his own on the heated floor in preference to piling upon other piglets. Since the floor surface is heated from within and substantially uniformly throughout its area, it provides equal degrees of comform and protection against the cold for all of the piglets in the enclosure without crowding and Without danger of injury.
The slab 23 is preferably thick enough so that, when it is laid on the earthen floor of a pen, its uppermost surface will be at a level such that mud and litter will not be scattered thereon to any substantial extent. Further, since the slab is monolithic and its uppermost surface can be quite smooth, it can be readily and frequently cleaned to maintain optimum sanitary conditions. The slab will be large enough, in its major dimensions, so that its upper surface will accommodate a significant number of piglets, preferably as many as normally comprise a single litter, stretched out comfortably and without undue crowding, but small enough, taking into consideration the material from which the slab is formed, so that it may be readily handled and moved from place to place by one man. The slab may be formed from Portland cement concrete, from molded or extrusion or thermo setting plastics or from other similar materials through which heat may be readily conducted. Thus it will be seen that we have used the term monolithic somewhat loosely; and that term is to be construed to include materials other than rock or concrete, so long as those materials are generally homogeneous.
In some instances, it may be desirable to use a plu-' rality of slabs arranged in juxtaposition to cover a relatively large floor area; though we presently believe'that ordinarily only one liter of piglets should be kept in a single enclosure.
Since pigs (and to some extent other animals and pets) will" chew any available material and could readily bite through the insulation of the leads 16 and 17, or even through the wires themselves, the provision of the armor 18 is highly desirable. For the same reason, we consider it important that theproximal end portion of the armor shall be embedded within the bodyof the slab 23 so that, no matter what may happen, not even a short length of the wires 16 and 17 closely adjacent the slab may become accessible to the pigs. We presently believe that the armor 18 should extend a distance of at least three feet from the edge 24 of the slab. The leads 16 and 17, of course, will extend far enough so that the plug 19 may be connected to a suitable source of electrical energy (not shown) at some remote point.
It is essential, of course, that the exposed, upper surface of the slab shall not be heated to a temperature such as to sear the hides or singe the coats of the pigs; and in some instances it may be desirable to install one or more thermostats within the length of the resistance element 13; or a manually-adjustable thermostat may be connected in the leads 16, 17 in analogy to the conventional practice in electric blankets. In practice, however, we have found that the character of the heating element and the physical characteristics of the slab, as well as the electrical characteristics of the energy supply source, may be so selected that the temperature of the exposed surface of the slab will remain within the range between 70 and 80 F., even without the installation of thermostats, under weather conditions encountered within the temperate zone and during which energization of the heating element is required.
Since, whenever the heating element is energized, heat radiates continuously from the exposed surfaces of the slab, there is a tendency for those slab surfaces to remain dry most of the time, and to dry off very quickly after wetting. Thus the slab disclosed herein gives new born piglets a warm,dry spot in which to rest and quickly become dry. Suflicient heat is radiated from the slab so that, even on very cold nights and even in installations in which the enclosure is a slatted pen, piglets will be saved from freezing and will be quite effectively protected against respiratory diseases resulting fromtemperature shock. In the same way, 'the device is disclosed, when installed in a dog house or encolsure for other pet, is highly attractive and very persuasive against night roaming.
We claim as our invention:
1. A combination heating and reinforcing structure adapted to be embedded in a portable slab, comprising a rigid grid made up of a plurality of substantially parallel, longitudinally-extending members and a plurality of substantially parallel, transversely-extending members bridging and welded to all of said longitudinally-extending members, an insulated electric resistance unit loosely woven through the mesh defined by said grid in a patterrn of substantially uniform distribution over the surface of said grid and free from attachment to said grid, and
flexible, insulated electric leads connected to the ends of said resistance unit and extending freely to a significant distance away from said grid.
2. A portable, warmed animal bed comprising a portable, monolithic slab having embedded therein a rigid grid made up of a plurality of substantially parallel longitudinal members and a plurality of substantially parallel transverse members bridging and fixedly secured to said longitudinal members, an insulated electric resistance unit loosely Woven through the mesh defined by said grid in a pattern of substantially uniform distribution over the surface of said grid and free from attachment to said grid, and flexible, insulated electric leads connected to the ends of said resistance unit and extending from said grid to emerge through an edge surface of said slab, said leads further extending freely to a significant distance away from said slab.
3. A combination heating and reinforcing structure adapted to be embedded in a portable slab, comprising a rigid grid made up of a plurality of substantially parallel, longitudinally-extending metal wires having a diameter of at least approximately one-eighth inch and a plurality of substantially parallel, transversely-extending metal wires having a diameter of at least approximately oneeighth inch bridging and welded to all of said longitudinally-extending members, an insulated electric resistance unit loosely woven through the mesh defined by said grid in a pattern of substantially uniform dis tribution over the surface of said grid and free from attachment to any of said wires, and flexible, insulated electric leads connected to the ends of said resistance unit and extending freely to a significant distance away from said grid.
References Cited in the file of this patent UNITED STATES PATENTS 1,349,136 Lillard Aug. 10, 1920 2,406,884 Mann et a1 Sept. 3, 1946 2,478,808 Deal Aug. 9, 1949 2,866,066 Neely Dec. 23, 1958 2,868,946 Stephenson Jan. 13, 1959 2,943,289 Colten et a1. June 28, 1960 2,961,524 Newman Nov. 22, 1960 2,997,568 Leipold et al Aug. 22, 1961 3,069,522 Jamison Dec. 18, 1962