US 2788804 A
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Description (OCR text may contain errors)
April 16, 1957 w. LARKIN 2,788,804
FLEXIBLE HOSE Original Filed July 20, 1950 United States Patent FLEXIBLE HOSE Walter Larkin, Norristown, Pa., assignor to Fidelity Machine Company, Inc., Philadelphia, Pa., a corporation of Pennsylvania Original application July 20, 1950, .Serial .No. 114,919. Divided and this application March 30, 1954, Serial No. 419,708
4 Claims. '(Cl. BS- 55) This invention relates primarily .to improvements .in flexible tubular products and more particularlyto tubular products of the class employing tubular sknitted fabrics as elements of the wall structure of the said product.
A principal object of the invention is .to provide a tubular product of thestated class having generally .improved physical characteristics coupled with improved economy of manufacture.
More specifically, an object of the invention is to provide a tubular product of .the stated class employing knitted tubular components of special .form conferring materially improved characteristics .upon the finished product.
Still more specifically, the invention contemplates .provision of a tubular product of the class described which by reason of the character of the knitted components exhibits materially improved properties including relatively great flexibility, r'elativelylhighburststrength,.substantial absence of inherent twist, and relatively high economy of production.
A further specific object of the invention is to provide a rubber or like hose of the stated class exhibiting all of the aforesaid improved characteristics.
The invention resides also in certainnovel structural details hereinafter described, and illustrated in the attached drawings wherein:
Fig. 1 shows a section of hose brokenLout toshowthe structural details including the tubular knitted fabric components;
Fig. 2 illustrates diagrammatically a piece of fabric of the character shown in Fig. 1;
Fig. 3 illustrates a piece of fabric constituting a modification within the scope of the invention, and
Fig. 4 is a fragmentary view similar to Fig. 1 showing the same form of fabric as in the latter figure but reversed face-wise.
With reference first to Figure l of the drawings, the tubular product therein illustrated as an embodiment of the invention consists of an inner tubular member 1 of flexible material, a tubular knit fabric 2 which closely embraces the tube 1; an inner flexible tubular envelope 3 overlying the knitted tube 2; a second tubular knit fabric 4 which closely embraces the envelope 3; and an outer flexible tubular envelope 5 which covers the knitted tube 4 and which forms the outer surface of the end product. The fabric tubes may be composed of cotton, nylon or any suitable natural or synthetic textile strand material; and the inner tubular member 1 and the envelopes 3 and 5 may be of rubber or rubberized or other flexible material impermeable to water. When so constituted the tubular product is adapted for use as hose or for other purposes requiring a tube or duct having water impermeable walls.
The tube illustrated in Fig. 1 and described in general terms above, is distinguished from prior tubular products of the same class primarily by the character and relative arrangement of the textile components 2 and 4. The form of the fabric is best shown in Fig. 2 wherein r 2,788,804 Ce Patented Apr. 16, 1957 :it will be noted that .the knitted web is composed of two mechanically interlocked .but otherwise independent setsof stitches 6 and 7, each set forming a continuous spiral course, Sand 9 respectively, see Fig. l, with the .convolutions of one spiral being interspersed with those of the other. Similarly, the wales 11 formed by'the interlocking .loops 12 of the one set of stitches 6 are interspersed withthe Wales 13 formed by the loops 14 of the .other set of stitches v7, as bestshown in Fig. 2.
The coursewiseruns of yarn 15 and 16 which extend between the adjoining loops in the respective course, cross-the loops of .the other course at one and the same face of the webso that the two sets of stitches are interlocked as stated above. In effect the individual .sets of stitches constitute two independent knitted webs which are mechanically unitedas described above intoa unitary fabric.
.A tubular knit fabric ofthis type has certain character'istics which render it particularly useful in a flexible tubular structure of the type to which the invention relates. .It .is, -for example, highly flexible; is highly resistant .tointernal bnrstingstresses; and exhibits econonly .of manufacture both in materials and in the rate of production. These characteristics are reflectedin the end product whereintheyhave special significance related to the function .of the tubular product and the purposes to which it-maybe applied.
With reference again. to Fig. v1, it will be noted that the fabric elements 2 and 4 are formed so that the spiral course of stitches in one extends oppositely to the spiral course of stitches in .theother, i. e. right and left hand spirals respectively. A circular knit fabric of this general type exhibits -an inherent tendency to twist spirally due to theaforesaid formation of the stitches in a spiral course or courses. Thisis particularly objectionable in tubularvproducts such as wateror other hose wherein the twist tendency of the fabric is transmitted to the end-product. .Lhave found that this otherwise undesirable effect .can be avoided or effectively neutralized, by the expedient of reversing the spirals in the two fabrics as described aboveso-that the hoseor other'tubular end product shows substantially no tendency to twist in either direction.
By reference to Fig. 1 it will be noted that the ribs formed by the wales in the knitted fabric lie on the outside of the knitted web. This is sometimes desirable as a medium for forming a firmer mechanical connection between the envelopes 3 and 5 and the knitted covers particularly where the envelope 5 is applied in plastic state. It will be noted, however, that the fabric may be reversed so that the ribs will lie on the inside, as illustrated in Fig. 4. Such reversal is illustrated in Figs. 1 and 3 of United States Patent No. 2,201,905. This latter arrangement has advantages in certain classes of hose wherein the inner tube 1 of rubber composition or other flexible plastic material is relatively thick as compared with the outer rubber or plastic envelope or envelopes. In such cases, the projecting ribs on the inner face of the knitted fabric may imbed themselves in the relatively thick body of the inner tube without affecting the inner smooth surface of the latter and the outer surface of the fabric which is relatively flat and smooth will then be capable of receiving a relatively thin outer envelope without adversely affecting the desirable smooth surface of the latter.
Another desirable characteristic of this type of fabric when used in a tubular structure of the character described resides in the fact that the fabric exhibits a much more uniform disposition of interstices over the face area of the fabric than knitted fabrics of other types. This will be apparent from an examination of Fig. 2 for example, wherein it will be noted that the major portion of the knitted loops in each instance lie described, in that they afford a passage for interbonding of the plastic or rubber components lying at the respective opposite sides of the knitted fabrics and a substantial uniformity of the small individual bonds which occur at the interstices is an important factor in affording a high uniformity of strength in the wall of the composite tube as a whole. 7
It will be noted also in the applicants structure that while the knitted loops are arranged in spiral courses in accordance with conventional knitting practice, the
rows of loops themselves extend longitudinally of the tubular structure. This arrangement in conjunction with In addition, the loops in the 7 the particularform of knitted fabric described above is calculated to afford not only a maximum and materially improved burst strength, but also maximum resistance to stretching of the tubular product in the longitudinal direction. This latter effect is of importance not only because it greatly increases the longitudinal or tensional strength of the tubular product, but also prevents the constriction of the diameteriof the bore which would necessarily accompany an elongation. 1 a
It is to be noted that a lock stitch fabric of this type having desired given characteristics may be'produced in machines employing more than two groups of needles with still greater economy of yarn. Such a fabric 'produced by use of three ditferent lengths of needles in interspersed groups is illustrated in Fig. 3. In this case the fabric comprises three separate spiral courses of 4 cation Serial No. 174,949, filed July 20, 1950, and since abandoned.
I claim: V
1. In a flexible tube of the class adapted for conduction of pressure fluid and whereof the wall is composed of plastic composition having therein a structural component in the form of a seamless knitted tube, the improvement which resides in the fact that the fabric of said knitted tube comprises a plurality of independently formed helical courses of stitches, each of said courses of stitches comprising laterally spaced wale forming loops and intervening lateral loop-connecting strands, the Wales formed by the loops of one course being interspersed coursewise with the wales formed by the loops of another course, and each loop-connecting strand in each of the courses extending across at least one loop of another course and on the same face of the knitted web as the loop-connecting strands of the other courses so as to'unite the courses into a unitary fabric conferring on the flexible tube a relatively high resistance to bursting by internal fluid pressure. 7 2. A flexible tube according to claim 1 wherein each of the loop-connecting strands in each course extends across a single loop of another course.
3. A flexible tube according to claim 2 wherein the independently formed helical courses are offset walewise and are uniformly spaced with respect to each other,
the said fabric thereby exhibiting a relatively uniform distribution of interstices through which the said plastic composition extends so as to establish continuity of said composition throughout the thickness of the wall of the tube.
4. A flexible tube according to claim 3 wherein the loop wales of the knitted fabric lie at the inner face of the latter, and wherein further the position of the fabric 'in the said' wall affords a'relatively great thickness of plastic composition on the wale side of the fabric.
.References Cited in the file of this patent UNITED STATES PATENTS I 1,947,302 Meiwalcl Feb. 13, 1934 1,972,755 Blaisdell Sept. 4, 1934 2,234,671 Ford Mar. 11, 1941 2,355,019 Stover Aug. 1, 1944