US3406967A - Loop erecting device - Google Patents

Description

Oct. 22, 1968 N. o. YOUNG LOOP ERECTING DEVICE Filed July 10, 1967 FIG.2

FIG.4

INVENTQR. NI ELS O. YOUNG FIG.3

ATTORNEY United States Patent "ice 3,406,967 LOOP ERECTING DEVICE Niels 0. Young, Lincoln, Mass., assignor to Block Engineering, Inc., Cambridge, Mass., a corporation of Delaware Continuation-impart of application Ser. No. 595,283,

Sept. 19, 1966. This application July 10, 1967, Ser.

8 Claims. (Cl. 272-8) ABSTRACT OF THE DISCLOSURE A device for driving an ordinarily limp, closed loop at speeds sufficient to erect the loop into a steady-state rigid configuration and formed of a tube through which a bight of the loop must pass, the tube having a tapered bore, an annular chamber disposed about the tube, an annular orifice joining the chamber and tube adjacent the more constricted end of the latter, and a pipe for passing fluid into the chamber.

This application is a continuation-in-part of copending application Ser. No. 595,283, filed Sept. 19, 1966, now Patent No. 3,330,557.

This invention relates to erecting systems and more particularly to means for erecting a flexible, closed loop into a substantially rigid structure.

Under ordinary circumstances, a flexible loop of material cannot assume a self-supporting configuration if it is completely compliant, i.e., lacks stiffness. The shape and size in which a flexible loop can be self-supporting depends largely upon the extent to which its degree of stiffness opposes loading, such as would be due to gravity.

It has now been found that a limp, i.e., compliant flexible loop of little or no stiffness moved along itself behaves as mechanically stiff, and can thus be erected to form a substantially rigid-appearing, self-supporting structure capable of astonishing extension.

It is, therefore, a principal object of the present invention to provide an erection system incorporating such a loop and operable to erect the loop into a substantially rigid-appearing elongated configuration. Devices incorporating the principles of such a system are quite simple to manufacture and operate, and thus lend themselves readily to use as toys which provide sustained fascination and amusement to the user.

Generally, such devices comprise an elongated flexible element or line-mass formed into an endless or closed loop, a guide in which a portion of the loop is mounted so that the loop is freely movable substantially longitudinally along the guide, and means for moving the loop through the guide with speed sufficient to cause the portion of the loop not constrained by the guide to erect into a substantially rigid structure. In a preferred embodiment the means for moving the loop is in the form of means for introducing a fluid flow into an air plenum chamber and then into the guide substantially uniformly through an annular orifice with a sufficient mass velocity component directed along the longitudinal axis of the guide such that passage of fluid into the guide will propel the loop at the desired speed. The guide preferably comprises means defining a channel of circular cross-section and increasingly tapered in inside diameter away from the annular orifice. The loop is, of course, moveable through that channel.

Other objects of the invention will in part be obvious and will in part appear hereinafter. The invention accordingly comprises the apparatus possessing the construction, combination of elements, and arrangement of parts and the method comprising the several steps and relation of 3,406,967 Patented Oct. 22, 1968 one or more such steps with respect to each of the others, all of which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the present invention, reference should be had to the following detailed description taken in connection with the accompanying drawings wherein:

FIG. 1 is an elevational view in cross-section through a simple embodiment of the principles of the present invention;

FIG. 2 is a cross-section of the embodiment of FIG. 1 taken along the line 2-2;

FIG. 3 is an elevational view in cross-section through yet another modification of a device embodying the principles of the present invention; and

FIG. 4 is a cross-section of the embodiment of FIG. 3 taken along the line 44.

Referring now to FIG. 1, there is shown an embodiment of the present invention comprising guide means in the form of elongated hollow tube 20. Positioned within the central base of tube 20 is a portion of flexible, normally limp, endless loop 22, dimensioned in cross-section so as to be freely movable through tube 20. Part of the loop therefore lies within tube 20, the remainder of the loop lying outside of tube 20. Both ingress end 24 and exit end 26 of tube 20 preferably have rounded lips to reduce snagging, wear and friction with loop 22 as the latter moves through the tube.

Tube 21} preferably is circular in cross section as shown in FIG. 2 and formed in two parts: section 28 which defines exit end 26 and a major portion of a circular-cross section interior channel or bore 30 of tube 20, and sec tion 32 which defines ingress end 24 and a major portion of the exterior periphery of the tube. The outside diameter of a portion of section 28 adjacent end 26 is the largest diameter and this portion is provided with an abutment or shoulder 34 of somewhat lesser diameter. The remainder of section 28 is formed as a pipe 36 having a cylindrical outside diameter still smaller than shoulder 34. The inside shape of the part of bore 30 defined by section 28 is tapered or flared, preferably much as a trumpet as shown in FIG. 1 from the largest inside diameter at end 26 to the smallest diameter adjacent other end 38 of pipe 36. A good approximation of the curved internal taper or flare of bore 30 can be achieved by making part of the interior of pipe 36 adjacent end 38 simply cylindrical, and the remainder of the interior of the pipe conical as shown in FIG. 2. While such an approximation is not quite as efiicient as the configuration of the bore of FIG. 1, it is easier to manufacture.

Section 32 has an outside diameter which matches that of section 28 adjacent end 26. End 24 preferably defines a coaxial central opening having a much smaller diameter than the outside diameter of section 32. The other end 40 of section 32 however has an internal diameter such that it will form a snug fit about shoulder 34, and the interior of section 32 is preferably cylindrical from end 40 almost to end 24. Thus, in effect, end 24 of section 32 is terminated with an annular ring-like wall 42 having a rounded exterior lip 44 and a rounded interior lip 46, both being segments of a zone of a torus. Because the radius of curvature of the lip 46 is less than that of the former (or alternatively, the radii are the same but the two segments have different diameters), the two rounded lips 44 and 46 meet to form a comparatively sharp, annular edge 48 preferably lying in a plane perpendicular to the longitudinal axis of tube 20. The diameter of edge 48 should be somewhat smaller than the interior diameter of pipe 36 at end 38 thereof.

It will be seen that when sections 28 and 32 are assembled by 'mating shoulder 34 with end 40, either by friction fit or with an adhesive, the difference between the outside diameter of pipe 36 and the inside diameter of the bulk of section 32 provides an annular chamber 50 wholly surrounding bore 30 and separated from the latter by pipe 36. However, as shown in FIG. 1, sections 32 and 28 are so dimensioned in length that end 38 and edge 48 are about coplanar and hence define an annular passage 52 between chamber 50 and bore 30.

The loop may be formed of a wide variety of materials. For example, the loop can be a beaded chain or string, the bead being formed of some lightweight material such as synthetic polymers, or light metals such as aluminum. The loop can be merely a rough surfaced cord or string of fibrous material such as cotton, wool or the like, or a smooth surfaced monofilament such as nylon. The fluid power required to drive the loop can be reduced by using a cord of low weight and density such as knitting yarn. The loop is shown in FIG. 1 simply as an endless length of fibrous material such as a cotton string, woolen yarn or the like, with a typical hairy or fibrous and therefore uneven surface. Loop 22 can bear slubs or the like in various colors if desired, provided however that the maximum diameter of the yarn is sufficiently less than the minimum internal diameter of bore 30, thereby allowing the yarn to pass freely through the tube. If the slubs are fairly uniformly distributed along the yarn, the motion of the yarn can produce a siren effect.

Thus, the combination of annular passage 52, the interior curvature of lip 46 and chamber 50 constitute means for introducing a fluid flow into tube 20 so that a major component of its flow direction is directed substantially along the longitudinal axis of at least part of the loop in tube 20 and toward exit end 26. To this end, there is also included hollow tube 54 mounted, for example, on the exterior of section 32 intermediate the ends of tube 20 and extending into chamber 50 so as to provide fluid communication with the latter. Preferably, tube 54 is located so that its point of entry into chamber 50 is remote from passage 52 thus insuring that the fluid flow is quite evenly distributed to passage 52.

In operation, fluid under pressure, such as orally expelled air, water from a hose, or the like, is applied to tube 54 entering therefore into chamber 50 and discharging from the latter through passage 52 into bore 30 and thence almost completely from exit end 26. This fluid flow through tube 20 drives loop 22 so that the latter moves continuously through tube 20. When the loop is driven at suflicient speed, the free portion of the loop (i.e., the loose part lying outside of and unconstrained by tube 20) will extend into an elongated, rigid, self-sup porting configuration. The size of the loop, and therefore the extent to which it becomes self-supporting depends on a number of factors, e.g., the loop density, the crosssection diameter of the bore, the length of loop, the mass velocity of the fluid, the compliance of the loop, and others. These factors, however, are all quite variable within wide limits. Chamber 50 serves as a reservoir of pressurized driving fluid and also serves to distribute the fluid mass so that the fluid flow through annular passage 52 is evenly dispensed. The taper or flare of bore 30 acts as an aerodynamic diffuser so that energy is efliciently transfered from the fluid stream in bore 30 to the loop portion disposed in the bore. The total mean included angle of the taper of bore 30 preferably lies between 2 and 9 to achieve superior results.

It is desired that the fluid jet from passage 52 be directed insofar as possible so that its major component is directed axially along bore 30 toward the wider end thereof. Also, the fluid jet should be relatively uniform, hence the clearance between edge 48 and the interior edge of pipe 36 at end 38 should be constant within about 20% or better, i.e., should not be eccentric. In one embodiment, a clearance of 0.020 inch has been found quite adequate for a bore of 0.25 inch diameter at end 38.

When the velocity of fluid through passage 52 is sufficient to force the loop to move at a certain minimum speed, the free portion of the loop is forced into a selfsupporting elongated configuration that remains quite rigid regardless of the orientation of the axis of loop elongation with respect to gravity. The loop will remain erected, i.e., self-supporting, for a few seconds even after the driving fluid flow is cut off, demonstrating that its rigidity depends on its own motion and not on support provided by the driving fluid.

Because the loop in this embodiment is quite light in weight, a substantial length up to several feet can readily be driven into erection with lung-power and maintained in its rigid state for several seconds. If one desires to use compressed gas sources such a carbon dioxide or tetrafluorethylene bottled under high pressures, loops of twenty or more feet long can readily be maintained in erection for much longer periods.

It is believed that the phenomenon observed occurs because the loop string or line-mass is under tension generated by its motion. For a string of density, P, moving at velocity, V, there is a tensile stress of U nearly independent of local curvature of the string, i.e.,

Now for a loop standing up to a height of h, the compressive stress 0,; generated by the weight of the linemass would be Where 3 is the acceleration due to gravity.

Since the string cannot endure compression without collapsing, being to some extent compliant, then for the string to be self-supporting, a must be greater than 0' or In other words the kinetic energy of the line-mass must always exceed its gravitational potential energy for the loop to be in erection. The simple analysis does not explain a number of curious properties that the standing loop exhibits, and which contribute toward the fascination that the device arouses in users. For example, an impulse applied transversely of the line-mass adjacent exit end 26 appears to propagate at approximately the velocity of the string toward the ingress end 24 of the device. Thus, the string follow translations of the device in the manner of a rigid structure. Rotation of the device about the axis of elongation of the standing string reveals effects which seem gyroscopic. Thus, if so rotated, rapidly the string forms a 'double helix having a plurality of turns, although the upper bight of the loop tends to maintain its original orientation. When the rotation about the axis of elongation is stopped, the upper bight appears to precess, slowly turning and unwinding the helix until the loop again lies substantially in a single plane.

The embodiment shown in FIGS. 3 and 4 (wherein like numerals denote like parts) basically is the same device as shown in FIGS. 1 and 2. However, as has been previously noted, eccentricity of passage 52 is undesirable. Hence, the device of FIGS. 3 and 4 includes a supporting spider mounted on section 32 adjacent end 38 of pipe 36, and formed typically of a number of projections or arms 56 extending inwardly from section 32 into contact with the exterior wall of pipe 36. These arms serve to centralize pipe 36 so that passage 52 will be and remain concentric. Of course, the arms should be of small dimensions compared to the cross-sectional area of chamber 50 so as not to impede significantly fluid flow through the latter. Alternatively, the supporting spider may be mounted on pipe 36 so as to extend outwardly into contact with the interior wall of section 32.

Also, as shown in FIG. 3, shoulder 34 and the interior periphery of the mating portion of end 40 of section 32 are threaded so section 28 can be screwed into section 32. This construction not only avoids the problem of close tolerance posed by friction fit, but allows axial adjustment of end 38 of pipe 36 with respect to edge 48 so that the dimensions of passage 52 can be altered within limits. This serves to adjust the relative air flow through passage 52.

It will be apparent that a number of other modifications can readily be made without altering the basic inventive concepts. For example, the flexibility of the loop does not preclude the quality of elasticity. Thus, the loop if formed, for example, of an elastically extensible yarn, when placed in its free standing mode will tend to elongate considerably. And while the device as hereinbefore described is particularly useful as a novel interesting toy, its principles are susceptible of many other applications.

Since certain changes may be made in the above apparatus without departing from the scope of the invention herein involved it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted in an illustrative and not in a limiting sense.

What is claimed is:

1. A device for erecting an elongated flexible element forming a closed loop substantially incapable of being self-supporting in static condition into a loop which is a substantially rigid structure, said device comprising, in combination:

means including a hollow elongated tube defining a path in which a portion of said element is disposed and constrained for movement substantially along the longitudinal axis of said portion, said tube being tapered internally along its axis of elongation; and

means for propelling said element with a fluid stream along its longitudinal axis in said path at a speed, as substantially the sole cause, sufi'icient to cause the unconstrained portions of said element to erect into said structure, said means for propelling including means defining an annular chamber disposed about said tube and an annular orifice joining said chamher and tube adjacent the narrower end of the latter.

2. A device as defined in claim 1 including means for introducing a fluid flow into said chamber at a point remote from said orifice.

3. A device as defined in claim 1 including means for adjusting the area of said orifice.

4. A device as defined in claim 3 including means for maintaining the concentricity between said orifice and the inner periphery of said tube adjacent said orifice.

5. A device as defined in claim 1 wherein said annular orifice has a mean diameter less than the inside diameter of said tube adjacent said orifice and is substantially concentric with said tube.

6. A device as defined in claim 5 wherein the inner diameter of said orifice is a substantially sharp inner edge of a ring-like member defining a central aperture adjacent said narrower end of said tube, the inner surface of said member facing said tube :being a toric segment curved for directing fluid flow from said chamber through said orifice substantially uniformly about said tube and toward the wider end of said tube.

7. A device as defined in claim 1 wherein said tube is internally shaped as a hollow conical portion and a hollow cylindrical portion meeting coaxially.

8. A device as defined in claim 1 wherein said tube is internally flared in a smooth trumpet shaped curve.

References Cited UNITED STATES PATENTS 1,966,895 7/ 1934 Kuhns 46-51 2,039,731 5/1936 Martin 4651 2,756,737 7/ 1056 Resch 46-44 X 3,180,043 4/ 1965 Larson 40-37 3,232,557 2/ 1966 Winn 22697 X FOREIGN PATENTS 639,136 11/1936 Germany. 662,613 7/ 1938 Germany.

OTHER REFERENCES Advertisement circular entitled Phony Squirts, published in -1965 by H. Fishlove and Co., 712-20 North Franklin St., Chicago, 111. 60610.

ANTON O. OECHSLE, Primary Examiner.

A. W. KRAMER, Assistant Examiner.

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