US2367944A - Metal conduit - Google Patents

Description

D. INGALLS METAL CONDUIT Jan. 233, 1945.

Filed Oct. 9, 1942 Flu-In! a fi. y. r 4 -.4

IN V EN TOR.

,47'TOQNEY Patented Jan. 23, 1945 STATES PATENT OFFER METAL CONDUI'E David Kngalls, Westficld, N. 3., asslgnor to Tite= flex, inc, Newark, N. it, a corporation oi New Jersey 8 (Claims.

This invention relates to improvements in conduits which are made substantially entirely of metal, whereby the durability of the conduit is increased and the qualities of the conduit as a against radio waves, and in other ways, is improved. it'especially relates to flexible cond may have uses in other applications.

object of the invention is to increase the .ty of conduits comprising corrugated, tubes having structures or members outthe tubes to reeniorce or protect the same other purposes. ihe accomplishment of the present invention, s providing a flat. metal strip exea hell-sall about tube and lying flatly it. :-y lying flatly against the tube it is ed to err--ress the strip is not interor interlaced with other strips so that it ield. iron: coming in contact with the tube lying smoothly upon the tube, the

true where the tube and conduit are flexible.

Where the tube is flexible the strip, by varying its breadth", thickness or the pitchof its helix, or all of them, may provide means of regulating flexibility and conversely the stiiiness, of the conduit, and this is further object of the invention.

iurther object of the invention is to provide improved means for reeni'orcing the corrugated tube against elongation. This may be accomplished by the helical strip lying flatly on the tube, being secured its ends to terminals to which the ends of the tube are secured, the strip by reason of its fiat-lying against the tube supplying a firm and unyielding means for this purpose.

A further object of the invention is to provide improved means for reenforcing the tube against twisting which is accomplished efficiently and unyieldingly by the metal strip lying flatly against the tube and secured at its ends to terminals to it oh the ends of the tube are secured.

a. single helical strip about the tube as de scribed, however, will only reenforce the tube against twisting in one direction, it is, therefore, a further object or the invention to guard against torsional forces in either direction by providing another fiat strip extending helically about the tube and the inner helical strip lying flatly against it, the added helical strip being wound in the opposite direction about the tube from the inner strip, the added strip passing outside the point by reason of underlying strip.

iii

inner flat-lying strip at all intersections so that the flat-lying or" the inner strip will not be interiered with, and the ends of each of the strips are secured to terminals secured to the ends of the tube.

in the patent to L. H. Brinkman No. 1,198,392, granted September 12, 1916, is described and shown a tube having a helical corrugation formed by helically disposing a metal strip having a central longitudinal fold or groove, the edges of adjacent convolutions being interfolded to form a fixed and tight seam. Such tube is flexible by the bending of the sides oi the corrugation toward and away from each other. This tube was admirable for many purposes, but it had certain vulnerabilities'among which may be mentioned sliding in the joint or seam when the tube was subjected to twisting, whereby the seam or joint might be loosened so that it might not be fluidtight, or further injury might be done to the tube; also the tube was liable to increase in length when subjected to high internal pressure or outside longitudinal tensioning forces. It is a further object of the invention to reenforce and strength such a tube against such vulnerabilities. This is done by placing a helical strip about the tube, which strip lies flat against the corrugations, and when such strip is secured to terminals to which the end of the tube is secured, it provides a firm and inextensible reeniorcement against the vulnerabilities stated. The strip extending helically about the tube in one direction only will, however, reenforce against twisting in one direction only. To accomplish reenforcement against twisting in either direction it is necessary to employ a strip helically wound about the tube in the opposite direction and secured to terminals which are secured to the end of the tube.

In order: to relieve against the vulnerabilities of the strip-formed tube as referred to, there was placed upon the tube a covering formed by interwoven or braided metal strands about the tube, some or" the strands of said covering being helically wound in one direction and other of said strands being wound in the opposite direction about the tube, and interlaced. These strands were secured at their ends to couplings secured at the ends or the tube. Such conduit is set forth in the patent to L. H. Brinkman No. 1,340,818, granted May 18, 1920, with particular reference to Fig. 5 thereof. Such a conduit has performed most eficient and satisfactory service. It has been found, however, that this conduit comprising the corrugated tube with the interlaced metal covering was likely to be injured and its life shortened by wearing of the tube corrugations by reason ofthe pressure against them of the interlaced covering especially at the points of crossing of the interlaced strands. Such wear was liable to occur not only when the conduit was flexed, but also when it was subjected to vibration. Such interlaced covering is desirable as a finish for the tube and as a protection against mechanical injury from without.

It is a further object of the invention to, in conduits of this character, lessen or obviate the wear of the tube by the interlaced metal covering. This is accomplished by interposing a flat strip lying flatly against the tube corrugations between the interlaced or interwoven outer covering and the corrugated tube whereby pressure of the intersection points of the strands and other points of the outer covering against the tube corrugation is relieved. Not only does such interposed strip guard-the corrugated tube against .wear, but when the interposed strip is helically wound about the corrugated tube and has its ends secured to the end terminals or couplings of 'such tube, it will provide a more firm and inextensible means for preventing lengthening of the corrugated tube under high internal pressure or high tensile stresses, and it will also form a firm and unyielding means for preventing twisting with consequent injury to the tube as above referred to.

It may, therefore, be said to be a further obiect of the invention to provide means for efflciently and unyieldingly reenforcing the tube against lengthening or twisting stresses. A strip helically wound in one direction only, however, will guard against twisting in but one direction only. Another flat strip helically wound about a corrugated tube in the other direction and also secured to the terminal couplings will reenforce against twisting in the other direction.

The use of one, two or more strips wound in the same or opposite directions may be employed also for the purpose of regulating or permitting the desired stiffness or flexibility of the conduit and also one or more strips may have the strip width or thickness or both varied for the purpose last mentioned or for other reasons. When there are superposed strips between the outer interlaced covering and the corrugated tube, each strip outside the one lying against the corrugated tube, passes outside its next inner strip 50 that there is no interlacing of the strips thereby rendering less liable wear upon the corrugated tube and the strips lie more flatly and firmly upon the tube.

It is also to be observed that the outer interlaced covering provides a means for holding the strip against the corrugated tube and prevents the strips within the covering and about the corrugated tube from unwinding or unraveling when such strips are unsecured to end terminals, the outer covering being braided on at the same time that the strip is applied to the tube and the braiding operation closely following up the winding of the strip.

While the invention has been above referred to as particularly useful in connection with a conduit comprising a strip-formed, helically-corrugated tube in combination with an outer, braided or interlaced, metal covering like that of the Brinkman Patent No. 1,340,818, particularly as described with reference to Fig. 5 thereof, the invention may have useful application in connection with other corrugated tubes, for instance as described in the patent to L. H. Brinkman No. 1,120,268, granted December 8, 1914, and also may flnd use in connection with corrugated tube without the outer braided covering.

Also while the strip or strips adjacent to and about the corrugated tube will usually be of metal, they may, under some conditions, be of suitable non-metallic material, as, for instance, where the desired function of such strip or strips interposed between a braided covering and the corrugated tube is simply to relieve the pressure of the covering on the tube, they may be of nonmetallic material such for instance as braided Fiberglass.

While a flat strip lying flatly against the corrugations of the tube has been referred to above, more than one such strip may be employed, the strips being wound in the same direction and the ends of all the strips may be secured to the terminals secured to the ends of the tube. Under such circumstances it will be apparent that each of the strips will fulfill the objects and purposes of a strip as hereinbefore set forth. Also there may be a plurality of strips overlying the strip or strips against the tube and wound in the opposite direction.

Other and ancillary objects of the invention will appear hereinafter and the invention will be pointed out in the appended claims.

In the accompanying drawing which illustrates the invention;

Fig. 1 is a side elevation of a conduit embodying the invention, partly broken away and partly in section;

Fig. 2 is a section on the line 2-2 of Fig. 1;

Fig. 3 is a side elevation, partly broken away and partly in section, of a modified construction of conduit embodying the invention;

Fig. 4 is a section on the line 44 of Fig. 3;

Fig. 5 is a side elevation, on a reduced scale, partly broken away and partly in section, of a length of the conduit as shown in Fig. 3 having terminals secured to its ends; and

5 Fig. 6 is a fragmentary view, on a reduced scale, showing a side elevation of a conduit having a plurality of flat lying strips against the tube and also a plurality of strips wound in the opposite direction and overlying the aforesaid strips, the conduit being partly broken away.

Referring to the drawing and first to Figs. 1, 2 and 3, the metal tube I having the helical corrugations 2, may be of the construction of tube as described and shown in the Brinkman Patent No. 1,198,392, this tube being formed as described in the said Brinkman, patent, of a helically disposed strip having alongitudinal fold or groove 3 with the edges of a convolution being interfolded with the edges of adjacent convolutions as at 4 and 5, the tube then having its corrugation sides reflexed by compressing the tube endwise.

Helically wound about the tube is a flat, metal strip 6 of substantially rectangular cross section and of greater width than thickness. This strip may have its corners rounded so as to reduce the wearing or cutting effect of the edge upon the tube upon which it is wound or any outer tube covering which may come in contact with it. The strip.

6 lies flatly against the corrugations 2 and the pitch of its helix is greater than the pitch of the helical corrugation 2 so that the strip 6 will bridge from one corrugation convolution to the next I whereby it is prevented from sinking into the depression between the corrugations and wearing sharply against the corrugation sides. The strip 8 is integral rather than being formed of a plurality of wires, whereby its wearing edges are reduced. Outside the fiat strip 6 is the braided metal covering a comprising the interlaced or interwoven metal strips 8 and t which are braided outside of the strip 5. Each of the strips'8 and 9 is flat, of substantially rectangular cross section and of greater width than thickness, each strip being integral in cross section rather than bein composed of a plurality of wires.

The strip lies flatly on the corrugation 2 and has less wearing eflect upon the corrugations than would be the case if the braided covering 7 were placed directly on the corrugations. When the braided covering is laid directly upon the corrugations 2 there is inward pressure or proie ions at the points of intersection of the interlaced strips of the braided covering so that the inner strip at the intersection, or inward projection formed therein at that point, causes considerable wear upon the corrugations of the inner tube, especiaily as the inner strip of the braid, or projection formed therein, has edges liable to 'cut or increase the wear on the inner tube. This may be illustrated by reference to Fig. 2 according to which the strip 9 of the outer braid is pressed in one direction by the middle one of the crossing strips 8 and outwardly by the strips 8 on each side thereof. This results in the inward bend to in the strip 9 which will cause a wearing projection or wearing pressure upon the corrugations 2 as just referred to. It will be understood that this condition will occur at all crossings of the interlaced strands of the braided covering '1 whether astrip s or a strip 9 is the inner one.

Byinterposing the helical strip 6 between the inner corrugated tube i and the braided covering 5, the braided covering is lifted away from the corrugations 2 so that pressure therebetween, or projections causing wear of the corrugations by the braided covering, is avoided.

The conduit as a whole is flexible, the inner tube i flexing by relative movement of the sides of its corrugations, which flexing is permitted by the helical strip b and the braided covering i. It is during the flexing of the conduit that the wear referred to is most likely to occur, but even where the conduit is in a use where it is not required to be flexed, serious wear may take place from vl= bration as where the conduit is used to house the ignition conductors of an internal combustion engine. The construction of the invention, may, therefore, be useful even when the conduit is not flexible or is not required to flex.

The strip d also provides a means for controlling the flexibility of the conduit as a whole by varying its pitch, width or thickness or all three or any two of them. The pitch of the strip it should be made as great as is consistent with the desired characteristics of the tube and the use to which it is to be put, as the greater the pitch the less will be the tendency of the edges oi the strip to wear the corrugations 2 of the inner tube i.

It will be seen that the conduit as described, being of metal, will operate as a shield against radio waves, as for instance where it is employed as a conduit for an ignition conductor of an in= ternal combustion engine, and when so employed the conduit may have its electrical conductivity, which is important in such shielding, varied by varying the cross section or material or both of the strip 6.

The braided outer covering may be applied to the conduit at the same time that the helical strip i3 is applied to the tube, the braiding closely following up the application of the spiral strip so that the spiral strip is held by the braid in position, and prevented from unraveling, during manthe helical corrugation and bridges from one cor-- rugation to the next.

Wound about the tube 1 and the strip Ii wound thereon, is the oppositely wound helical metal strip l2 passing outside of the strip II at all their crossings. The strip l2 also bridges from one convolution of the corrugation 2 to the next and is of greater pitch than the helical tube oorrugation, the pitch of the-helix of the strip I2 being approximately equal to that or the strip II and each of the strips II and i2 is of less width than the strip 6.

Outside the tube and the two strips ll and I! wound thereon, and lying against the strips, is the braided or interwoven metal outer covering 1, the same as the braided covering 1 of Fig. 1. The use of the two narrow helical strips I] and 12 instead of the broad strip 5 of Fig. 1, changes the flexibility of the conduit as is desirable for certain uses, while at the same time protecting the tube 1' from undue pressure upon it at wearing points of the braided covering 1'.

In Fig. 5 is shown the conduit of Figs. 3 and 4 with terminals or couplings l3 and 14 secured to its ends, the corrugated tube l', the metal strips I l and i2, and the outer braided covering 1 being entered within the coupling H as shown and securely soldered therein, thereby securing them to the coupling and to each other. At the other end of the conduit the tube 2', the strips II and i2 and the braided outer covering I are entered within the coupling or terminal l3, the same as in the coupling or terminal l4, and are securely soldered therein whereby they are secured to the coupling and to each other. The ends of the tube, strips and braided covering having their ends secured together, and the strips ii and 92 being oppositely helically' wound, reenforce the conduit against torsional stresses in both directions and also against tensional or lengthening stresses applied either by high pressures upon the interior of the tube or external tensioning force applied to the couplings. In the case of the conduit structure of Fig. l, the corrugated tube, the strip helically wound and lying flatly thereon and the outer braided covering may have the ends of the tube, strip and covering entered into a coupling and soldered securely therein at each end of the conduit in a manner similar to the securing of the tube, strips and braided covering in the couplings as shown in Fig. 5.

In the case of Fig. 1, however, the helical strip 5 will only reen'force the conduit against twisting in one direction, but it will also reenforce the conduit against elongation.

Referring to Fig. 6, there is therein shown a. plurality of metal strips 55 and it helically wound about and lying flat upon the corrugated metal tube 9" which is the same as the corrugated tube i and i of the structures of Figs. 1, 3 and 5, said strips i5 and it being wound in the same direction and opposite to the direction oi.

winding of the helical corrugation of the tube 8''.

Wound about the tube I" and the strips l5 and I6 thereon are th helical strips l1 and I8 wound in a direction opposite that of the strips l5 and I6 and being outside the strips 15 and I6 at all crossing points. Outside the strips I1 and I8 is the braided metal covering 1 the same as the similar covering of the structures of Figs. 1, 3 and 5. The ends 'of the strips, the corrugated tube and the braided covering may be secured in a terminal at each end of the conduit as described in connection with Fig. 5, and the strips l5, I6, I! and I8 will then function to reenforce the conduit against torsional stresses in both directions and also stresses tending to elongate the conduit. The plurality of strips lying flatly against the corrugated tube and also a plurality of oppositely wound strips lying outside the tube contactin strips at all crossing points may be employed to regulate the flexibility of the conduit or for other purposes, by varying the size, number and relationship of the strips to produce the desired result,

It will be obvious from the foregoing that any desired number of strips lying against the tube or any desired number of overlying strips may be employed to achieve the desired conduit properties.

While the invention has been illustrated in what are considered its best applications it may have other embodiments without departing from its spirit and is not, therefore, limited to the structures of the drawing.

What I claim is:

1. A conduit comprising in combination a corrugated, metal tube and a flat, metal strip helically disposed about said tube and lying flatly against the corrugations of said tube.

--- -2,sc7,a44

2. A conduit comprising in combination a metal tube having a helical corrugation and a flat, metal strip helically disposed about said tube and lying flatly against the corrugations of said tube, said helical strip being of greater pitch than the helical corrugation of said tube.

3. A conduit comprising in combination a metal tube having a helical corrugation and a flat, metal strip helically disposed about said tube and lying flatly against the corrugations of said tube, the direction of said helical strip being opposite to that of said helical corrugation.

4. A conduit comprising in combination a corrugated, metal tube and a plurality of flat, metal strips helically disposed about said tube and lying flatly against the corrugation of said tube.

5. A conduit comprising in combination a corrugated, metal tube, a flat, metal strip helically disposed about said tube and lying flatly against the corrugations of said tube and a braided metal covering about said tube and strip.

6. A conduit comprising in combination a corrugated, metal tube and a flat strip helically disposed about said tube and lying flatly against the corrugations of said tube.

7. A conduit comprising in combination a corrugated, metal tube, a flat strip helically disposed about said tube and lying flatly against the corrugations of said tube and a braided metal covering about said tube and strip,

8. A conduit comprising in combination a corru ated, metal tube, a plurality of flat strips helically disposed about said tube and lying flatly against the corrugations of said tube and a braided, metal covering about said tube and strips.

DAVID INGALLS.

Images