US3441712A - Flexible multiconductor heater - Google Patents

Description

April 29, 1969 p. HYNES I 3,441,712

FLEXIBLE MULT I CONDUCTOR HEATER Filed Oct. 25; 1967 INVENTOR. Lee fi/gizeo" ATTORNEY,

CYLINDER 4 RETRAC I 5/ 4 ADVANCED April 9, 1969 L. P. HYNES 3,441,712

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Y afii uwau scam ATTORNEYS United States Patent 3,441,712 FLEXIBLE MULTICONDUCTOR HEATER Lee P. Hynes, Haddoniield, N.J., assignor to Hynes Electric Heating Company, Kenilworth, N.J., a corporation of New Jersey Filed Oct. 23, 1967, Ser. No. 677,149 Int. Cl. Hb 3/06 US. Cl. 219-539 3 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a multiresistor flexible electric heater which is adapted to fit in a hose, conduit, or pipe.

A purpose of the invention is to give flexibility to an electric heater in all directions to facilitate bending ac cording to the shape of a hose, conduit or pipe.

A further purpose is to aid in replacing broken insulators without disassembling an entire electric heater.

A further purpose is to grip the resistors between tongues of three or more insulator segments, so that a band holding together the insulator segments will also apply gripping pressure on the resistors.

A further purpose is to grip the resistors between insulator segments and an insulator core.

A further purpose is to cross-connect between resistors within radial slots of an end insulator.

A further purpose is to permit automatic or semiautomatic assembling of the insulator segments at intervals along an electric heater.

A further purpose is to assemble the insulator segments in a jig.

Further purposes appear in the specification and in the claims.

In the drawings I have chosen to illustrate a few only of the numerous embodiments in which the invention may appear, selecting the forms shown from the standpoints of convenience in illustration, satisfactory operation and clear demonstration of the principles involved.

FIGURE 1 is a diagrammatic top plan view showing the chuck and the welding means for causing the insulator segments to grip the resistors preparator to joining a band surrounding the insulator segments.

FIGURE 2 is a view similar to FIGURE 1 with the chuck closed and the welding elements in the process of completing a weld.

FIGURE 3 is a view similar to FIGURE 2 showing the insulator after bending back the outwardly extending ends of the band.

FIGURE 3a is a face view of the tongue and the gripping recess of one of the insulators.

FIGURE 3b is a view corresponding to FIGURE 3 showing a modified construction of one of the insulators in which the gripping surfaces extend clear across.

FIGURE 3c is a view similar to FIGURE 3 showing a die making indentations on the band to tighten the band.

FIGURE 4 is a section on the line 44 of FIGURE 3.

FIGURE 5 is a diagrammatic side elevation showing one position of the chuck.

FIGURE 6 is a diagrammatic side elevation showing the mechanism for advancing and retracting the chuck.

FIGURE 7 is a cycle diagram showing the operation of any suitable controls such as valves for the advance cylinders and the chuck cylinders.

FIGURE 8 is a top plan view of a jig for assembling insulator segments.

FIGURE 9 is a section on the line 9-9 of FIGURE 8.

FIGURE 10 is a view similar to FIGURE 9 showing the lowermost resistors in place.

FIGURE 11 is a section on the line 11-11 of FIG- URE 8.

FIGURE 12 is a section on the line 12-12 of FIG- URE 8.

FIGURE 13 is a transverse sectional view showing an assembly of insulator portions for an electric heater having six resistors.

FIGURE 13a is a view similar to FIGURE 13 showing a modified form of the insulator of the invention.

FIGURE 14 is a partially sectional fragmentary side elevation of the end portion of an electric heater showing one way for insulating the jumpers.

FIGURE 15 is a right end elevation of FIGURE 14.

FIGURE 16 is a view similar to FIGURE 14, showing a different form of insulation for the jumpers at the end.

My US. Patent 3,286,078 illustrates in FIGURE 7 a form of separable insulator for use with two electric resistors in an electric heater. This form gives considerable flexibility but is limited in the sharpness of bends which are permissible.

My U.S. Patent 2,963,539 shows an electric heater which is flexible in certain directions but not flexible in one particular direction.

The present invention is concerned with an electric heater of greatly improved flexibility, which is suited particularly for inclusion in a hose, conduit or pipe, and which is adaptable where three or more resistors are used.

There are several different reasons for using three or more resistors. One common reason is to make the circuit convenient for a multi-phase power source, particularly a three-phase source.

Even on single-phase installations, however, there is a demand for a spare resistor which can be energized without disassembling the electric heater itself, merely by changing the connections at one end. This allows for the possibility that one resistor may be burned out or otherwise rendered inoperative.

In some types of service, also, it is desired to have more uniform distribution of a source of heat around the hose or pipe, and this is a further reason which favors the use of three or more resistors.

It will be evident that while the invention will serve for heaters which are installed in rigid piping or the like, including piping having a spiral shape or sharp bends, it is also very effective for use within flexible hose, for example, corrugated stainless steel hose or plastic hose. Heated hoses of this type are desirable, for example, to heat tank cars and other containers to fluidize the contents, and to heat inlet and discharge hoses.

The invention thus provides a very effective flexible heater having three or more resistors, and also facilitates replacement of insulators and portions of insulators which may break either during manufacture or in service. It is no longer necessary to string insulators from the end in order to replace them.

Considering first the form of FIGURES l to 7, I there show helically wound electric resistor coils 20 of suitable electric resistance wire, for example Nichrome, Inconel, Monel, or otherwise, which have flexibility or resilience laterally and are resilient radially and thus can be contracted by gripping. Monel is an alloy containing nickel and copper, the nickel being approximately twice the copper in weight percent. Inconel is a nickel base alloy containing about 13% of chromium, about 6% of iron and small amounts of manganese, silicon and copper.

In the form under discussion, three insulator segments 21, preferably of ceramic or porcelain or other heat resisting insulating material (hereinafter called ceramic), have outer arcuate portions 22 which are intended to form part of a circular outside contour of the insulator, and also radially inwardly projecting tongue portions 23.

Each of the tongue portions at its sides has a longitudinally extending recess 24 which is adapted to engage and grip one of the sides of one of the coiled resistors At the middle of the arcuate portion 22 and extending around it is a recess 25 which is to receive a band such as a strap or wire holding together the insulator segments.

The arcuate portion of the insulator segments have at their forward and rear corners fillets 26 which are intended to protect against jambing on obstructions in the hose or pipe.

As best seen in FIGURE 1, jaws 27 of a chuck 28 sur round the insulator segments, and receive them within the curved inner portions of the jaws, along with a suitable sheet steel strap or band 30 in the recess 25. In order to prevent the segments from dropping through the chuck jaws 27, the jaws have at the bottom leaf spring metal fingers 31 which can retract out of the way when the jaw must move longitudinally with respect to the insulator segments.

In the preferred embodiment each of the jaws 27 has over its inner face a rubber or elastomeric gripping surface 32 which is capable when the jaws are compressed of engaging not only the outside edges 33 of the insulator segments but also the band so as to push it into hugging relation as desired.

The electric resistors as shown in FIGURE 1 are equally circumferentially positioned as at the corners of an equilateral triangle, so that they are opposite the recesses 24.

FIGURE 2 shows pressure being applied to close the chuck jaws 27 as indicated by arrows 34, so that the walls of each of the recesses 24 on the opposite sides of the tongues 23 engage and pinch the resistor coils, contracting them slightly radially inwardly so that the coils are unable to slip longitudinally with respect to the resistors.

FIGURE 1 shows ends 35 of the band or strap 30 engaged by open electrodes 36 of a spot welding mechanism and as shown in FIGURE 2. the electrodes 36 close as indicated by arrows 37 and spot welding current is passed through the electrodes so as to create a spot weld at 38 uniting together the ends of the band 30.

It will be evident that other techniques for fastening the ends of the band can be used, including overlapping and welding, soldering, and mechanical interlocking as by folding together, bending together, twisting and affixin-g cleats or other fastening devices.

These ends 35 are bent in the circumferential direction as shown at 40 in FIGURE 3, a convenient way being by hitting the ends with a hammer or by using a similar motion of a die.

Thus it will be seen that the finished insulator as shown in FIGURE 3 has a portion of its outer circumference formed by each one of the insulator segments.

In some cases it is preferable to form threads or gripping surfaces 41 (hereinafter called corrugations) on the faces of the recesses 24 of the insulator segments as shown in FIGURE 3a, in order to more effectively guard against the possibility of slippage of the resistor coils through the insulator. If it is desired, the gripping surfaces may extend entirely across the surface of the nose and the recesses at each side as shown in FIGURE 3b at 41'.

It is important that the band be tight. If difficulty is encountered in maintaining the band tight by the particular fastening means used, the band can be further tightened as shown in FIGURE 3c by forming inward bends or indentations in the band at 39 opposite the gaps between the insulators, as by moving radially inwardly die projections 39, using a mechanism for example similar to the means for manipulating the chucks as in FIGURE 6. The effectiveness of the indentations in maintaining tightness will be increased by using a band which is relatively stilf, as for example, a fairly stilf wire.

As shown in FIGURE 5 the resistor coils can be fed from spools not shown through a guide trough 45 and guiding eyes 46 so that the resistors descend vertically as shown at 47 into the chuck 28 in FIGURE 5.

As shown in FIGURE 6 the chuck consists of a housing 48 sliding on vertical guides 50 under the action of a double acting cylinder and piston combination 51 anchored at one end on an abutment 52 and secured to the chuck housing 48 at the other end. Each chuck jaw 27 is preferably energized to move it in and out by a double acting fluid piston and cylinder combination 53, it being evident, of course, that fluid is admitted and discharged from each end of each cylinder by valves.

FIGURE 7 shows conveniently the operation of the cylinders, without concern with the well known features of the valve mechanism. As shown, the operation of the advance cylinder is indicated by curve 54 and the operation of the chuck cylinders is shown by curve 55. At a given starting point the advance cylinder is retracted as suggested by line 56, and the chuck is, of course, in its uppermost position. The chuck cylinders are operating to hold the chuck open as shown by line 57 on the curve 55. When the insulator segments and the band are properly in place in the chuck with respect to the resistors, the chuck closes as shown by line 58 of curve 55, the closed position being suggested by line 60. Then the band is welded and the ends of the band are bent back out of the way. After the chuck is closed and the welding is complete, the advance cylinder advances as indicated by line 61 on curve 56, the advance position of the advance cylinder being shown by line 62. Then as suggested by line 63 on curve the chuck cylinders open the cuhck and as shown by line 64 on curve 54 the advance cylinder is then retracted, moving the chuck back, the spring fingers 31 yielding to allow the chuck to pass over the forwardly positioned insulator segments without pulling the entire heater back from its forward position. If friction is not sufficient to hold the insulator in forward position, a ratchet and pawl, not shown, may be used as well known in the art.

It will be evident that the fluid means on the chuck must permit regulation of its pressure or its pressure must be regulated by springs as well known in the chuck art.

Of course, the distance between centers of insulators can be varied in the forms shown, it being of the order of 2 inches or 2 /2 inches in the preferred form, so that there is a considerable length of resistors between insulators to provide for flexibility in all directions.

The combination of insulators and resistors making up the heater can conveniently be changed to a horizontal direction by elbow 65 and then the heater can be directly fed into a flexible hose or pipe as desired at 66. If preferred, the combination of the resistors and insulators can be shipped to the point of installation as a roll or coil.

Thus it will be evident that in the form of FIGURES l to 7 the resistors are preferably fed vertically and the insulator segments are assembled on them and held in place by the band on a vertical axis and by automatic or semiautomatic operation.

In some cases it may be preferable to assemble the components horizontally, using a troughlike jig as shown in FIGURES 8 to 12 inclusive.

In this case the resistors 20 are fed suitably in equally circumferentially displaced position horizontally through the length of the jig 70, which is provided with a bottom 71, boxlike side walls 72 and at suitable places along the length notches 73 in the side walls for receipt of the insulator segments.

In FIGURE 9 the resistors are eliminated for clarity of illustration and in FIGURE 10 one of the resistors is eliminated for this purpose.

At a point opposite the notches 73 the side walls have near the top notches 74 and receive a U-shaped band, in this case a wire 25', the open part of the U being disposed upwardly. The bottom of the U rests on the bottom 71 of the jig and the band extends through the side notches 73 as best seen in FIGURE 9. A bottom insulator segment 21 is rested on the bottom as shown in FIGURES 8 and 9 with the tongue 23 central ond upstanding, the band extending'through a groove 30' in the outside circumference of the insulator segment.

As shown in FIGURE 10, the resistors are rested in the recesses 24 on either side of the tongue 23 of the upwardly disposed insulator segment 21. They are restrained from movement outwand by shoulders 75 in the side walls.

In the next step as shown in FIGURE 11 at the next insulator position, insulator segments 21 are disposed at each side with the tongues 23 directed downward and the lower recesses 24 resting on the top and outside portions of the resistors 20. The bottom portions of the sidetmost insulator segments are engaged and supported by the walls of the notches 73 and the circumferential grooves 30' in the outsides of the insulator segments are in line with the band As shown in FIGURE 11, pins 76 in the center of the jig support the center upper resistor.

As shown in FIGURE 12, the upper side insulator segments are pushed toward one another and downward so that each one of the resistors is firmly gripped between opposed sides of insulator segments and pinched radially inward so that it is no longer free to move longitudinally, and band 25 is joined by twisting at 38' so as to tightly hug the insulator segments and confine them as shown in FIGURE 12.

The previous forms show desirable means and processes for assembling insulator segments on three resistors.

In FIGURE 13 I show a construction for positioning six resistors 20 at each of the insulator locations. In this form a suitably generally hexagonal insulator core 80 has at what would othenwise be each hexagon corner a recess 24' for receiving a resistor.

Insulator segments 21 each having opposed legs 81 bent at an angle corresponding to the corner angle and intermediate resistor receiving recesses 24 are positioned at points to engage and radially contract each of the coiled resistors against its resilient tendency to radially expand, thus gripping the resistor against longitudinal motion. Each of the insulator segments has around the outside circumference a groove 25 which receives a band and when the segments are tightend to grip the resistors against the insulator core the ends of the band are joined as by twisting at 38'.

It will be understood that the form shown in FIGURE 13 can be modified to accommodate other numbers of resistors greater than three, for example, four, six, eight or nine.

FIGURE 13a shows a modification of the fiorm of FIGURE 13, in which the inner core 80' has a series of axially extending outer recesses 24 in this case six, and each insulator segment 21 brings pressure inwardly on two resistors 20 by virtue of the band 30, which extends around a recess in the outer circumference of the insulators. Each of the insulators has two recesses 24 and an intervening tongue portion 23.

If an insulator segment breaks, then the band 30 can be cut, and a replacement segment inserted and a new band fastened in place.

For many circuit arrangements the electric feeding connections will be all at one end and suitable jumpers or cross connections will be applied at the far end.

In the case of three-phase star connection or single phase with a spare resistor, it is important to be able to cross connect the three conductors at the end remote from the end where the power is fed.

In FIGURES l4 and 15 jumper portions 82 are bent from the end of each resistor and joined at 83 and the joint is protected as by a screw-on insulator cap 84 shown in FIGURE 14.

In FIGURE 16 a special end insulator 85 is provided with openings 86 for the jumper portions 82 of the resistors, the endmost portion of the insulator 85 having three radially converging grooves 87 which are deep enough to receive and insulate the twisted joint 83 common to the three resistors. The jumper portions themselves hold the endmost insulator 85 in place.

It will be understood, of course, other connections can be used as desired. For example, in a three-phase circuit the connections may be star or delta, and any suitable arrangement may be used for other numbers of phases.

In view of my invention and disclosure, variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art to obtain all or part of the benefits of my invention without copying the structure, mechanism and process shown, and I, therefore, claim all such insofar as they fall within the reasonable spirit and scope of my claims.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. In an electric heater, three parallel helical metallic electric resistors which are resilient radially and laterally, the resistors being equally circumferentially spaced from one another, a plurality of longitudinally spaced ceramic insulators, each of which is composed of three insulator segments, each insulator segment having a projecting tongue extending radially inward between two resistors, having a longitudinal groove in each of two opposite sides of the tongue provided with corrugations which receive and grip one of the helical resistors and radially compresses the resistor against its radial resilience, the insulator segments having an external annular groove, and band means in the groove holding the insulator segments in gripping engagement with the helical resistors.

2. In an electric heater, more than three parallel helical metallic electric resistors which are resilient radially and laterally, the resistors being equally circumferentially spaced from one another, a plurality of longitudinally spaced ceramic insulators, each of which has at least three insulator segments and an insulating core portion which is radially within the resistors and has a longitudinally outwardly disposed groove engaging the inside of each resistor, each insulator segment engaging the outside of a resistor, there being on the engaging surfaces of the insulator segments and the core portion corrugations which grip the resistors to radially compress the resistors against their radial resilience, the insulator segments having an external annular groove, and band means in the groove holding the insulator segments in gripping engagement with the helical resistors.

3. In an electric heater, six parallel helical metallic electrical resistors which are resilient radially and laterally, the resistors being equally circumferentially spaced from one another, a plurality of longitudinally spaced ceramic insulators, each of which is composed of at least three insulator segments and having an insulating core portion which is radially within the resistors and has a longitudinal outwardly disposed groove provided with corrugations which engage the inside of each resistor, each insulator segment engaging the outside of a resistor and having corrugations which grip it against the insulator core portion and radially compress the resistor against its radial resilience, the insulator segments having an 7 8 external annular groove, and band means in the groove 2,515,603 7/1950 Kaplan 174-155 holding the insulator segments in gripping engagement 2,639,312 5/1953 Kerwin 174-88 X with the helical resistor. 2,790,889 4/ 1957 Hynes 219--539 X 2,963,539 12/1960 Hynes 174-138 References Cited 3,045,097 7/ 1962 Sellers L 219-552 X UNITED STATES PATENTS 3,286,078 11/1966 Hynes l 219-306 275,425 4/1883 Shelbourne 174-99 VOLODYMYR Y. MAYEWSKY, Primary Examiner. 354,892 12/1886 Du Bois 174-99 US Cl XR 873,456 12/1907 Ottinger 174--155 X 1,013,241 1/1912 Van Etten 174-155 10 17499,155;219550

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