US1975321A - Electric heater - Google Patents

Description

Oct. 2, 1934. c. s. HAWLEY ET Al. 1,975,321

ELEQTRIC -HEATER Filed Feb. fr. 1951 2 sheets-sheet 1 gnvcnfoza Carnel/ @Haw/ey ithel-lgbrf J. Parsons Oct. 2, 1934. c. s. HAWLEY ET AL ELECTRIC HEATER Filed Feb. 7, 1951 2 Sheets-Sheet 2 FIG. 5

FIG. 7

.m 5 MMM QMS Mv f Hh J d# ne, Ww KRW Patented Oct. 2, 1934 ELECTRIC HEATER Cornell S. Hawley, Albany, and Robert vJ. Parsons, Schenectady, N. Y., assignors to Consolidated Car-Heating Company,

Inc., Albany,

N. Y., a corporation of New York Application February 7, 1931, Serial No. 514,282

3 Claims. (Cl. 21S-19) For a detailed description of the present form of our invention, reference may be had to the following specification and to the accompanying drawings forming a part thereof, wherein Fig. l is a side elevation partly in section,

Fig. 2 shows diagrammatically-the connection of two panel type heaters,

Fig. 3 is a section on line 3 3 of Fig. 1,

Fig. 4 is an end elevation,

Figs. 5, 8 and 7 show the end blocks in detail.

Our invention relates to certain improvements in an electric heater of the well known type wherein a coil of resistance wire is wound helically around a central, grooved core of porcelain or similar insulating material. In endeavoring to increase the capacity of a heater of this type, We have found that we can bring the successive turns of the helix closer together-that is, we can wind the helix at a smaller angle with respect to the v axis of the core-by forming the bottom of the groove in which the helix lies with a semi-circular seat or" short radius in which the coil is tted and of a depth suicient to engage a substantial portion of the coil, so as to hold it against longitudinal displacement, while outside of and on either side of said coil-seat the upper part of the wall of the groove is cut away to leave but a thin barrier between the succeeding seats aforesaid and the coil-turns therein which, however, permits ample exposure of the coil to the air. By this expedient we are able to gain about twentyiive per cent. in the amount and weight of porcelain with respect to heater-wire that could be practically employed on our standard heater of 35 this type.

What we do is to use a smaller and lighter porcelain than before for a larger amount of wire and are thereby able to place a two-coil heater in the same casing that we formerly used for a single-coil heater. We have also provided this heater with a removable end block containing four or two terminals which can be applied to either end of the heater. This permits us to use but one form of heater for either a car-seat, under which the heater is applied transversely of the car, or for the truss-plank or car-panel beside the seat, where the heater extends longitudinally of the car. Heretofore it has been necessary to provide two different forms of heater for the two respective purposes. Other minor features of novelty, including a novel form of end block, will be referred to hereinafter.

Referring tothe drawings, A represents a cylindrical core, preferably of porcelain, on which two coils of resisting wire are Wound in a helical route.

A corresponding helical groove is ordinarily formed on the outside of core A to receive the coil. Our present invention includes the formation of this groove with a shallow semi-circular seat at its bottom for the coil extending between s the points a and b. The depth of this seat is only sufficient to embrace but a short arc in the coil circumference and to retain the coil against displacement along the length of the core. On either sideV of this coil-seat the former porcelain wall is cut away at the point c, leaving butv a cornparatively thin porcelain barrier between the successive turns of the coils. Thus each edge of the coil-seat aforesaid forms, in effect, a ridge following along the wall of the main groove and parallel therewith, which increases the creepage distance between coils. Thereby that portion of the Wall separating the consecutive turns of the coil and which rises above the semicircular coilseat is relieved of all duty as a coil-retainer, and may be much thinner than heretofore, while the removal of the aforesaid cut-away portion thereof allows for more adequate access of the air to the coil and affords more complete exposure of the heated wire of the coil while it also extends the creepage surface between adjacent coils. Yet the thinner barrier of porcelain may still project above the coil if desired and remain adequate to guard it against accidental contact with external objects.

As appears in Fig. 3, the porcelain core A is perforated axially by a square hole through which is threaded a metal rod C. To one or to each end of the core is applied a separable rectangular block D which also has a central square hole traversed by said rod C. Thereby the block D is maintained in a fixed angular relation to the angular relation of the core A against which it abuts. At the opposite end of core A, in the event of only one block D being used, an insulating washer E is applied and a nut, or nuts on the rod C serve to clamp both the washer E and the block D in position against the respective ends of the core. In case the heater is to be of the cross-seat type, only one block D is used at one end, the block D at the opposite end being replaced by a washer E.

It will be observed that tlere are two parallel coils in the respective grooves of the core, their ends connected respectively at block D by two of the four binding posts on that block but connected to each other at their opposite ends, thus the two coils will form a loop between the said two binding posts on D and the heater is then suitable for the cross-seat, being supplied by longitudinal lead wires in the panel beside the seat, between which lead wires the said loop is connected. But, if the heater is to be of the truss-plank or panel type, then a block D is applied to each end of the core and connection established between coils of succeeding heaters'as indicated in Fig. 2.

As appears in Figs. 5, 6 and '1, the block D may, to advantage, have the particular'form therein shown. The body of block D is provided with a forward oiset D1 on which is a removable plate D2 with a hole D3 grooved between D1 and D2'. On the body of D are the connection-clips X and Y. The approaching Wires l0 and 12 enter through the hole D3, as shown in Fig. '7, and their ends are engaged by the respective clips X and Y. Then the plate D2 is screwed down to clampV the Wires in said hole D3, thereby relieving any stress on the connection of thetwires with clips X and Y. As appears in the form of block D shown in Figs. 1 4, each coil on the 'helix is terminated some distance back of the block D but the uncoiled length of wire beyond the helix is continued along the bottom of the porcelain groove till it reaches its binding post and is connected thereto. Thus there is no interference between the coil and the binding post. The core is glazed throughout, both internally and externally.

What we claim as new and desire to secure by Letters Patent is: g

l. In an electric heater, an.V approximately cylindrical core having a circumferential helically-disposed groove, the bottom of which is provided with an arcuate coil-retaining seat of short radius but of a depth and contour constructed and arranged to engage a substantial portion of the coil and to positively hold the coil against displacement longitudinally of the core, said seat providing a continuous unbroken coil-retaining area, said groove having relatively thin walls forming a dielectric barrier between the grooved convolutions, the edges of said seat being spaced from said walls so as to provide ample exposure ofthe coil to the air.

` 2. In an electric heater, anA approximately cylindrical core having a circumferential helically-disposed groove, the bottom of which is provided With an arcuate coil-retaining seat of short radius but o1" a depth and contour constructed and arranged to engage a substantial portion of @the coil and to hold the coil against displacement longitudinally of the core, said seat providing a continuous unbroken coil-retaining area, said groove having relatively thin walls forming a dielectric barrier between the grooved convolutions, the edges of said seat being spaced from said walls and joined therewith by helically arranged shoulders so as to provide ample exposure of the coil to the air. Y l

- 3. In a two-coil electric heater, a refractory core, a removable end block therefor provided with conductor clips, said block being prOvided with an offset projection adjacent to said clips and having a conductor channel therein, and a clamp complemental to the oiset projection of said block, said clamp being constructed and arranged to anchor one or more conductors within said channel so as to relieve said clips of any stress due to the connection of the conductors therewith.

' CORNELL S. HAWLEY.

ROBERT J. PARSONS.

Images