US3823279A

US3823279A - Flexible power connection means for traveling elements

Info

Publication number: US3823279A
Authority: US
Inventors: D Rausch; P Johnston
Original assignee: Diamond Power Specialty Corp
Current assignee: Babcock and Wilcox Co
Priority date: 1973-03-12
Filing date: 1973-03-12
Publication date: 1974-07-09
Anticipated expiration: 1991-07-09
Also published as: BR7401829D0; NL154882B; NL7402538A; SU546303A3; FR2221836A1; SE397753B; GB1420538A; AU476914B2; DE2405789A1; BE811664A; CA990262A; AU6591374A; IT1008360B; JPS5523007B2; FR2221836B1; DE2405789B2; JPS49127191A

Abstract

A helically coiled flexible electrical conductor extensible and retractable axially to provide electrical connection to a movable element is slidably supported on a rod which extends through it. Convolutions at the movable end of the coil also overengage a controlling member movable with the movable element and which limits forces exerted upon portions of the conductor close to its movable end.

Description

United States Patent 1191 Rausch et a1.

11] 3,823,279 1451 July 9, 1974 8/1945 Wilson 191/12 R FLEXIBLE POWER CONNECTION MEANS 2,383,031

FOR TRAVELING ELEMENTS 3,608,125 9/1971 Nelson 191/12 R [75] Inventors: $31,? SEE Johnston Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-D. W. Keen Assignee: Diamond Press Specialty Attorney, Agent, or Firm-Harness, Dickey & Pierce Corporation, Lancaster, Ohio [22] Filed: Mar. 12, 1973 [57] ABSTRACT PP 340,116 A helically coiled flexible electrical conductor extensible and retractable axially to provide electrical con- 52 us. c1. 191 12 R 137 355.16 nection to a movable element is Slidably Supported lSll Int. Cl :HOZQ 11/00 a rod which extends through Convolutions at the [58] Field of Search 191/12 137,355.16 35520 movable end of the coil also overengage a controlling member movable with the movable element and which [56] References Cited limits forces exerted upon portions of the conductor UNITED STATES PATENTS 1 close to its movable end. 2,118,731 '5/1938 Knott 191/12 R A 1 19 Claim, 7 DrawingFigures if I! 1 FLEXIBLE POWER CONNECTION MEANS FOR TRAVELING ELEMEN'IS BACKGROUND OF THE INVENTION The present invention relates to conductors for providing connection to movable elements and has been developed in connection with work directed to overcoming problems which arise where a power connection must be provided to a movable motor such as is employed in long traveling soot blowers wherein the motor and a supporting carriage travel with a long lance tube, the carriage, motor and lance tube being typically supported on tracks carried by a substantially horizontal beam structure, the carriage being arranged to travel along the beam for distances which may be as great as 50 or 60 feet. The motor may be either electric or air powered. Various power feeding means of extensible and retractable character have been employed. In boiler environments where soot blowers are utilized, several factors tend to shorten the life of the equipment. Such factors include heat, vibration, and the presence of abrasive flyash in the atmosphere. Sliding electrical contacts are inefficient and undesirable in such environments, so that some form of continuous cable is desirable to supply electric power. The life of electric cables employed in this service has been less than satisfactory, however, due to the repeated flexing of the cable as well as the factors above mentioned.

U. S. Pat. No. 3,608,125 granted Sept. 28, 1971 to John E. Nelson discloses one solution to this problem which has found commercial use. In such patented construction a flexible helically coiled conductor rests in a tube or trough formed of or surfaced with a low-friction plastic and having a slot in the bottom for the escape of flyash. One end of the coil is fixed and receives power from a source of current (or'air under pressure) and the other or free end is connected to the motor and to an actuating element which moves the free end axially to accommodate the movement of the carriage by extending and contracting the coil axially.

Twofactors which limit the useful life of the aforementioned patented constructions are the abrasive effect of flyash, which cannot be eliminated by means of a supporting trough or tube, and the fact that the convolutions of the helix closest to the actuator are worked more severely than those farther from the actuator, as the served apparatus and actuator move.

lt has also been proposed to suspend such a helically coiled power supply cord on an internal rod (see British Pat. No. 956,163). Although such an arrangement substantially eliminates the abrasive problem resulting from flyash in the atmosphere, other severe problems are then encounteredjone of these problems being the tendency of the coil and its supporting rod to sag, which not only interferes with operation, and consumes more space, but may interfere with other moving parts, when used in a confined space such as inside the hollow beam of a soot blower of the indicated variety. Another problem results from the fact that where long travels are involved, the leading convolutions, which are first pulled away from the collapsed helix when starting from the retracted position, may be stretched so severely, before the friction and inertia of the later coils are overcome, that the helix diameter of the stretched leading coils is reduced (as this part of the cable attempts topull to a straight line) to such extent that the 2 leading coils actually grip and bind on the supporting rod. This completely stops extension of the coil without permitting full extensive movement of convolutions farther to the rear. Attempts to overcome the sagging difficulty by increasing the diameter of the supporting rod aggravate the binding problem, and shorten still further the attainable travel. Of course the internal rodtype support does not eliminate the problem of overworking and premature failure of the convolutions close to the moving end.

The present invention aims to improve upon the prior art arrangements and to provide a conductive connection to a traveling load or served apparatus wherein the conductor, in the form of a helix, is suspended on an internal rod but is provided with simple and effective means whereby overstressing of the convolutions is substantially. eliminated and the effective life of the conductor is greatly lengthened.

A related object is to provide such a construction which is inexpensive, easy to service when necessary, and which occupies minimum space.

Other objects and advantages will become apparent upon'consideration of the present disclosure in its entirety.

BRIEF DESCRIPTION OF THE FIGURES OF DRAWING FIG. I is a side elevational view of a known type of soot blower, illustrative of apparatus with which this invention is adapted to be usefully employed;

FIG. 2 is a vertical sectional longitudinal view on a somewhat larger scale illustrating a preferred embodiment of the invention;

FIG. 3 is a crosssectional view taken substantially on the line Ill-Ill of FIG. 2 and looking in the direction of the arrows;

FIG. 4 is a fragmentary view of portions of the apparatus close to the actuating portion, viewed as in FIG. 2 but showing the helix extended;

FIGS. 5 and 6 are cross-sectional views of the expansion controlling member taken as indicated by the lines and arrows V-V and Vl-Vl respectively of FIG. 2, and looking in the direction of the arrows, but on a larger scale and with portions omitted; and

FIG. 7 is a plan view of the expansion control member.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF .THE INVENTION The soot blower is shown as a well-known type of IX long retracting blower comprising a main sup porting beam 20,in the general form of an inverted U- channel, and which incorporates longitudinal supporting rails as 21 upon which a carriage 22 is rollably supported. (Only one rail is shown, but they are on both sides, as is well known.) Carriage 22 incorporates a motor 28, a transmission 29, and supporting and driving means enabling it to drive itself and the lance tube 25 axially by means of a gear (not shown) which meshes with and rolls along the bottom of rack 23. The motor, through gearing in the carriage (and also unshown), also rotates the lance tube. The outer end of the lance tube and its nozzle means 26 are thus projectable into and retractable from the interior of a boiler or other heat exchanger when appropriate power is supplied to motor 28. A blower of this type is fully disclosed in US. Pat. No. 3,439,376.

' Although a soot blower powered by an electric motor is illustrated and described in connection with the invention, it will be recognized that the invention might be used in other environments, and that the flexible conductor might be a tube for a fluid, rather than an electrical conductor. (Of course the word rod is intended to encompassany suitable internal support of restricted cross-section.)

The motor 28 derives its power from a suitable source of electricity which is deliverable through conventional means (not shown) to the vicinity of the rear end wall 30 of the soot blower, where it is electrically connected to the fixedly secured end portion 31 of the helically coiled flexible conductor 32. The end portion 31 is shown as secured to the beam near the rear wall 30 by a clip-like bracket 33. The coiled conductor 32 is suspended upon a rod 35 formed of steel having a low-friction covering such as the nylon sheath 36. The rod is fastened at its rear end to the wall 30 and at its forward end to a front wall 38.

Actuating means for the movable free end of the coil comprises a rigid bracket arm assembly generally designated attached to the carriage 22 and having a verti-- cal arm portion 42 which extends to a position close to and somewhat below and to one side of the rod 35. A transverse. arm 44 attached to the arm 42 extends spacedly below and transversely of the rod 35 across the forward end of the coiled conductor 32 as best shown in FIG. 3, and carries a control cone member 55 presently to be considered in greater detail. The control cone, which is attached to the rear face of arm 44 by machine screws 49, has a flat vertical base defining a wall 51 to which is attached a supporting slide-block 45 grooved at 53 to receive and positioned to underlie and support the rod 35 against sagging. Block 45 may be formed of or coated with low-friction material. In a preferred construction it has been formed of nylon impregnated with molybdenum disulfide. The arm 44 is provided with vertically oriented slots 46 for the bolts 47 which secure it to the vertical arm 42, and with horizontal slots 48 for the bolts 49. The block 45 and cone 55 are thus adjustable both vertically and horizontally to permit locating them accurately with respect to the rod and to compensate for variant positionings of the carriage with respect to the beam and other components.

The forward end of the flexible conductor 32 is clamped as by the bracket 50 for the arm 42 and as shown in FIG. 2 an extended portion 32' of the conductor is led to a junction box 52 on the carriage to provide power connection to the motor 28.

It will be appreciated that when the carriage moves forwardly (toward the right, as viewed in the drawing) from its retracted position shown in FIG. 2 in which the coiled conductor is contracted to minimum length, the tension on the forward or connected end of the helix in the region of the clip 50 is opposed by the drag and inertia of the conductor, and the efiect of each convolution, as it'pulls the next following convolution toward the rear of the assembly, is to stretch the coil axially so that the helix angle increases the helix diameter decreases. Torsion is thereby also exerted on the conductor. By reason of the fact that successive convolutions oppose such extension, the greatest force is exerted on the portion of the coiled conductor close to the bracket 50. It was found in extensive testing of constructions which lacked the control features of the present invention, having rod-supported coils, that failures occur relatively quickly in this region, and that this type of failure is the first to occur.

In order to control the expansion of such critical portions of the conductor close to the actuating portion and bracket 50, we provide expansion-controlling means comprising the generally conic supplemental supporting and inhibiting member 55, previously mentioned, attached to the rear face of the arm 42 and extending into the interior of the helically coiled conductor. The upper surface portion 56 of the control cone 55 is arranged horizontally and projects above the supporting rod 35, which lies in a slot 58 which extends longitudinally the full length of thecontrol cone, so that the convolutions which overlie the cone are supported upon the cone rather than upon the rod itself. As the carriage moves forwardly, convolutions toward the rear are successively pulled off of the cone; Friction between the cone and the convolutions tends to oppose extension of the convolutions on the cone, thereby reducing the stressing and torsion exerted upon such convolutions. In addition, as brought out in FIG. 2, the diameter of the cone in its region closest to the actuating arm.42 approaches the internal helix diameter of the coiled conductor when the latter is collapsed to its shortest axial length. The cone is relatively long, extending somewhat more than half the length of the collapsed helix in the construction shown, which is for a travel of 25 feet. Thus when the leading convolution 61 of the conductor is pulled forwardly by the bracket 50, the stretching of such leading convolution, as it tends to increase the helix angle and reduce the diameter in this region of the conductor, is limited by the wrapped engagement between such convolution and the surface of the cone (FIG. 4). Similarly, the second convolution 63 is limited in its extensionby its wrapped frictional engagement with the cone surface, although the linear extent of wrapped engagement may not extend the full length of the second convolution.

The cone is made of or surfaced with a smooth but relatively non-slippery material, cast aluminum having been used by us. Due to its length and gradual taper,

the leading convolutions grip and are pulled by the cone without permitting the portion of the coil closest to the leading end to flex unduly or to carry the tensile stress required to extend the coil, the force required to pull out the coil being distributed throughout the length of the portions which grip the cone. Overworking of the next succeeding convolutions toward the rear during the initial part of the travel is adequately prevented by the adhesive or frictional drag between the upper cone surface and the convolutions, which, as noted previously, successively tend to move rearwardly upon and drop off of the cone as the carriage moves forwardly prior to the stretching of the leading convolutions to the gripping condition.

The rod 35 is positioned low enough in the slot 58 so that the coils which overlie the cone do not touch the rod, as noted. The rod is maintained spacedly above the bottom of the slot 58 by the bearing block 45.

At its rear end the control cone is provided with a smoothly contoured extremity 65 which is curved downwardly toward the rear to provide a gradual lifting effect which assists the convolutions to return to the top of the cone as the carriage returns to the rear.

This Detailed Description of Preferred Form of the Invention, and the accompanying drawings, have been furnished in compliance with the statutory requirement to set forth the best mode contemplated by the inventors of carrying out the invention. The prior portions consisting of the Abstract of the Disclosure and the Background of the Invention are furnished without prejudice to comply with administrative requirements of the Patent Office.

What is claimed is:

1. Conductor means of the type which includes a helically coiled flexible member surrounding and suspended upon a supporting rod and axially slidably extensible and contractable on the rod, and an actuating portion for moving one end area of the flexible member axially relatively to a remote area thereof to extend and contract the helix, the internal diameter of the helix being substantially greater than the outside diameter of the rod, characterized by an expansion controlling portion movable with said actuating portion and extending into the helix and having portion radially outspaced from the rod and engageable by portions of the flexible member near said one end to oppose relative axial movement between such engageable portions of the flexible member and said actuating portion.

2.-Conductor means as defined in claim 1 wherein the controlling portion extends into the helix .at said one end of the coiled flexible member and is frictionally engageable with and disengageable from convolutions of the helical coil during movement of the actuating portion.

3. Conductor means as defined in claim 2 wherein said controlling portion includes a part projecting higher than the rod.

4. Conductor means as defined in claim 2 wherein said controlling portion includes a part projecting higher than the rod and extending longitudinally thereof and supporting convolutions of the coil spacedly above the rod.

5. Conductor means as defined in claim 1 wherein the controlling portion extends into the helix at said one end of the flexible member and has a part spaced from the top of the rod by a distance which approximates the internal helix diameterof the coiled flexible member, whereby said controlling member opposes radial contraction of the helix and limits stress applied to portions of the flexible member which overlie the controlling portion.

6. Conductor means as defined in claim 5 wherein the controlling portion is of tapering form in a vertical dimension which increases in a direction toward the actuating portion.

7. Conductor means as defined in claim 5 wherein the controlling portion is of tapering form having a substantially horizontal top at an elevation above the bar and an inclined bottom portion which diverges downwardly in a direction toward the actuating portion.

8. Conductor means as defined in claim 1 wherein the controlling member is of generally conic form.

9. Conductor means as defined in claim 5 wherein the controlling member is of generally conic form.

10. Conductor means as defined in claim 7 wherein the controlling member is of generally conic form.

11. Conductor means as defined in claim 7 wherein the controlling member is of generally conic fomi, the bar lying in an open-topped longitudinal groove in the controlling member.

12. Conductor means as defined in claim 11 including a supporting slide bearing portion slidably underengaging the rod, the controlling portion and slide bearing portion being attached to the actuating portion, the controlling member also having a guiding portion at its end farthest from the actuating portion inclined downwardly in a direction away from the actuating portion to an elevation below the bar to guideconvolutions upwardly off of the bar and onto the controlling portion during movement in the contracting direction.

13. Conductor means as defined in claim 1 wherein the controlling portion has longitudinally spaced parts of variant cross-section interposed between the rod and the interior of the helix defined by the flexible member.

14. Conductor means as defined in claim 1 wherein the controlling portion has longitudinally spaced parts of variant cross-section interposed between the rod and the interior of the helix defined by the flexible member, including a trailing part for imposing frictional resistance to escape of convolutions from the controlling portion during an initial portion of forward travel of the actuating portion and a part of greater cross section adapted to be constrictingly gripped by a forward convolution section of the flexible portion during a later portion of such forward travel.

l5. Conductor means of the type which includes a helically coiled flexible member surrounding and suspended upon a supporting rod and axially slidably extensible and contractable on'the rod, and an actuating portion for moving one end area of the flexible member axially relatively to a remote area thereof to extend and contract the helix, 'the internal diameter of the helix being substantially greater than the outside diameter of the rod, characterized by a support movable with the actuating portion and underengaging the rod to inhibit sagging of the rod.

16. In combination with means as defined in claim 1, a support underengaging the rod to inhibit sagging thereof, said support being fixed with respect to and traveling with the expansion controlling portion.

17. A combination as defined in claim 1 including a support underengaging the rod to inhibit sagging thereof, said support being fixed with respect to and traveling with the expansion controlling portion and urging the rod away from the controlling portion to prevent unwanted frictional engagement between said portion and rod.

18. In a soot blower construction of the type having a supporting beam,a carriage movable along the beam, a motor movable with the carriage, means for supplying power to the motor including a flexible conductor helically coiled about an axis extending longitudinally of the beam, a rod fixed to the beam and extending through and supporting the conductor, one end of the conductor being fixed to the beam and the other end fast with respect to the motor and carriage whereby movement .of the carriage along the beam extends and contracts the helix, and an extension controlling portion at least partly surrounding the rod and movable along the rod and beam with the carriage, said controlling member extending into the helix and having portions radially outspaced from the rod and engageable by portions of the conductor at a position spaced from said other end of the conductor to oppose relative axial movement between such engageable portions of the conductor and the carriage.

l9. Conductor means of the type which includes a helically coiled flexible member surrounding and suspended upon a supporting rod and axially slidably extensible and contractable on the rod, and an actuating portion for moving one end area of the flexible member axially relatively to a remote area thereof to extend and contract the helix, the internal diameter of the helix being substantially greater than the outside diameter of the rod, characterized by an expansion controlling portion movable with said actuating portion and extending UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 823, 279 Dated July 9, 1974 Inventor(s) David A. Rausch and Paul R. Johnston It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 49, efter 50, "for" should be --to-. Column 3, line 62, after "increases" insert --and--.

Signed and sealed this 29th day of October 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents

Claims

2. Conductor means as defined in claim 1 wherein the controlling portion extends into the helix at said one end of the coiled flexible member and is frictionally engageable with and disengageAble from convolutions of the helical coil during movement of the actuating portion.

5. Conductor means as defined in claim 1 wherein the controlling portion extends into the helix at said one end of the flexible member and has a part spaced from the top of the rod by a distance which approximates the internal helix diameter of the coiled flexible member, whereby said controlling member opposes radial contraction of the helix and limits stress applied to portions of the flexible member which overlie the controlling portion.

11. Conductor means as defined in claim 7 wherein the controlling member is of generally conic form, the bar lying in an open-topped longitudinal groove in the controlling member.

12. Conductor means as defined in claim 11 including a supporting slide bearing portion slidably underengaging the rod, the controlling portion and slide bearing portion being attached to the actuating portion, the controlling member also having a guiding portion at its end farthest from the actuating portion inclined downwardly in a direction away from the actuating portion to an elevation below the bar to guide convolutions upwardly off of the bar and onto the controlling portion during movement in the contracting direction.

15. Conductor means of the type which includes a helically coiled flexible member surrounding and suspended upon a supporting rod and axially slidably extensible and contractable on the rod, and an actuating portion for moving one end area of the flexible member axially relatively to a remote area thereof to extend and contract the helix, the internal diameter of the helix being substantially greater than the outside diameter of the rod, characterized by a support movable with the actuating portion and underengaging the rod to inhibit sagging of the rod.

18. In a soot blower construction of the type having a supporting beam, a carriage movable along the beam, a motor movable with the carriage, means for supplying power to the motor including a flexible conductor helically coiled about an axis extending longitudinally of the beam, a rod fixed to the beam and extending through and supporting the conductor, one end of the conductor being fixed to the beam and the other end fast with respect to the motor and carriage whereby movement of the carriage along the beam extends and contracts the helix, and an extension controlling portion at least partly surrounding the rod and movable along the rod and beam with the carriage, said controlling member extending into the helix and having portions radially outspaced from the rod and engageable by portions of the conductor at a position spaced from said other end of the conductor to oppose relative axial movement between such engageable portions of the conductor and the carriage.

19. Conductor means of the type which includes a helically coiled flexible member surrounding and suspended upon a supporting rod and axially slidably extensible and contractable on the rod, and an actuating portion for moving one end area of the flexible member axially relatively to a remote area thereof to extend and contract the helix, the internal diameter of the helix being substantially greater than the outside diameter of the rod, characterized by an expansion controlling portion movable with said actuating portion and extending into the helix and having portions radially outspaced from the rod and engageable by portions of the flexible member at a position spaced from said one end to oppose relative axial movement between such engageable portions of the flexible member and said actuating portion.