US3694094A

US3694094A - Borescope with variable angle scope

Info

Publication number: US3694094A
Application number: US100639A
Authority: US
Inventors: Drury K Mitchell
Original assignee: National Aeronautics and Space Administration NASA
Current assignee: National Aeronautics and Space Administration NASA
Priority date: 1970-12-22
Filing date: 1970-12-22
Publication date: 1972-09-26
Anticipated expiration: 1989-09-26

Abstract

A borescope with an adjustable hinged telescoping optical system which will permit visual inspection of bore surfaces at angles greater than 90*.

Description

United States Patent Low et al.

[451 Sept. 26, 1972 1 BORESCOPE WITH VARIABLE ANGLE SCOPE [72] lnventors: George M. Low, Acting Administrator of the National Aeronautics and Space Administration with respect to an invention of; Drury K. Mitchell, 3543 Chowning Court, Columbus, Ohio 43220 2,424,064 7/1947 Stegeman ..128/6 X 2,788,390 4/1957 Sheldon ..l28/8 X 3,285,122 l/1966 Buchbinder et a1. ..356/24l 3,519,363 7/1970 Ritcher et a1. ..356/24l 3,221,593 12/1965 Ferris ..350/293 X 1,915,811 6/1933 Wolf ..128/7 2,975,785 3/1961 Sheldon 128/6 3,294,085 12/1966 Wallace ..356/24l X 3,481,660 12/1969 Sheldon ..356/24l X 944,830 12/ l 909 Sussmann 1 28/8 2,609,728 9/1952 Cadwell ..250/25 FOREIGN PATENTS OR APPLICATIONS 6,853 8/1879 Germany ..128/8 190,703 4/1906 Germany 128/8 Primary Examiner-Ronald L. Wibert Assistant Examiner-Orville B. Chew, ll Attorney-L. D. Wofi'ord, Jr., C. C. Wells and John R. Manning [5 7 ABSTRACT A borescope with an adjustable hinged telescoping optical system which will permit visual inspection of bore surfaces at angles greater than 90.

6 Claims, 11 Drawing Figures PATENTEDsarzs I972 SHEET 1 OF 6 FIG.

APPLICANT Administrator of NASA with respect to an invention of DRURY K MITCHELL ATTORNEY PATENTEDSEPZB m2 3. 694.094

FIG.2

- APPLICANT O 1 Administrator of NASA 3 with respect to on c) m i S invention of w v 43 BY DRURY K. MITCHELL ATTORNEY PATENTEDsms I972 sum 3 or a A S A H O f 0 t mam e r m mm m ml n AW P D. A o

DRURY K. MITCHELL ATTORNEY PATENTEDfiEPZS I972 SHEEI l- UF 6 FIG.5

APPLICANT Administrator of NASA with respect to an invention of DRURY K. MITCHELL FIG.7

ATTORNEY PATENTEDSP26 I972 SHEET 5 UF 6 APPLICANT Administrator of NASA with respect to an invention of DRURY K. MITCH ELL FIG. IO

ATTORNEY ORIGIN OF THE INVENTION The invention described herein was made in the performance of work under a NASA contract and is subject to the provisions of Section 305 of the National Aeronautics and Space Act of 1958, Public Law 85-568 (72 Stat. 435, 42 USC 2457).

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to devices for inspection of hollow bodies, which devices are commonly referred to as borescopes. More specifically, the invention relates to a borescope which may be inserted about different and sharp bends in the bore adjacent its exit opening.

2. Description of the Prior Art The need for the internal examination of curved pipes and coils has resulted in the development of a variety of inspection devices to accomplish this difficult inspection task. One highly sophisticated device has a semi-flexible body carrying a television camera on the end thereof. The camera carrying end is inserted through the exit opening of the bore and pushed through the curves or bends until the camera is located at the area to be examined, and the image is electronically transmitted to a conveniently located receiver. Another device suggested for use has a slender, flexible body with an internal fiber optics for transmitting the image back to the pipe opening. However, with these prior devices it is necessary to move the entire body structure back and forth to adequately inspect some critical bore surface, and such movement is difficult to accomplish through a sharp angle in the bore.

Accordingly, it is an object of the present invention to provide a mechanical optical borescope with an easily adjustable inspection head.

Another object is to provide a borescope with modifying sections so it may be inserted about different and sharp pipe angles.

Other and further objects, uses, and advantages of the present invention will become apparent as the description proceeds.

BRIEF DESCRIPTION OF THE INVENTION The borescope of the present invention is particularly designed for the inspection of the interior or bore of a pipe line which may have a bend. Yet, it can be used effectively on straight pipe lines. The device consists of a straight tubular barrel with operator viewing eyepiece on one end and a telescoping head assembly on the other. Between the tubular barrel and head assembly may be inserted an adjustable hinged portion so as to position the head assembly through a sharp bend in the pipe. Further, for use about even sharper bends in the pipe, a fixed angle portion may be inserted between the telescoping head assembly and adjustable hinge portionn. The telescoping head carries a mirror and illumination means such that an operator looking through the eyepiece can view the illuminated interior side walls of the bore.

This will be more readily understood by the following detailed description when taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates the borescope of the present invention inserted in a pipe end;

FIG. 2 illustrates the telescoping head assembly end of the borescope of FIG. 1;

FIG. 3 illustrates the eyepiece end of the borescope of FIG. 1;

FIG. 4 is an end view of the head assembly taken along line 4 4 of FIG. 2;

FIG. 5 is a sectional view taken along line 5-5 of FIG. 2, illustrating the mirror within the fixed angle portIon;

FIG. 6 is a sectional view taken along line 6--6 of FIG. 2 showing the interconnecting gas flow pipe for the adjustable hinge portion;

FIG. 7 is a sectional view taken along line 7-7 of FIG. 2 showing the mirror within the adjustable hinge portion;

FIG. 8 is a sectional view taken along line 8-8 of FIG. 3 showing the roller attachment;

FIG. 9 is a side view of the spring loaded roller, taken along line 9-9 of FIG. 8;

FIG. 10 is a bottom view of the adjustable hinge portion, taken along line 10-10 of FIG. 7; and

FIG. 11 is a view of the rear support taken along line 11-11 ofFlG. 3

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT The borescope 21 of the present invention is shown in FIG. 1 in an operative position for inspection of a bore surface 23 about a sharp pipe bend 25. The borescope 21 consists essentially of an eyepiece assembly 27, a tubular barrel 29, an adjustable hinged portion 31, a fixed angle portion 33, and a telescoping head assembly 35. Both the adjustable hinged portion 31 and fixed angle portion 33 may be omitted for inspection of a straight bore. The hinged portion 31 is inserted between the telescoping head 35 and tubular barrel 29 to enable the head 35 to be positioned about a bend 25 in the bore. For those bore bends which exceed the capability of the hinged portion 31, the additional fixed angle portion 33 may be inserted to successfully position the head 35.

The telescoping head 35, shown extended by the broken lines 36 of FIG. 1, is composed, as indicated best by FIG. 2, of about five straight cylinders 37 of diminishing diameters that slide on one another from a minimum nested length to a maximum expanded length. Threaded onto the forward end of the smallest diameter cylinder is a cage-like housing 39 having spacer post members 41 supporting a front member 43 which, as shown by FIG. 4, contains a cluster of light bulbs 45. On the rear side of the front member 43, just behind the light bulbs 45, is located a right angle conical mirror 47 (shown in FIG. 2). The image of a circumferential strip of the bore surface, broken only by the interferring spacer post members 41 is reflected by the mirror 47 along the optical axis 48 of the borescope 21 toward its viewing end. The front member 43 is protected along its front and sides by transparent material 49 such as Lucite which allow the bulbs 45 to illuminate the bore for viewing.

The telescoping head 35 is expanded by gas pressure introduced through an inlet port 51, see FIG. 3, at the rear or viewing end of the tubular barrel 29. The head 35 is retracted by draw wires 53 on opposed sides of the borescope 21 which wires 53 lead back toward the viewing end. Guide fasteners 55 along the outer surface of the borescope 21 keep the wires 53in alignment. As indicated by FIG. 4, two opposed supports 57 extend from the forward end of the smallest diameter cylinder 37 adjacent the cluster of light bulbs 45, and the draw wires 53 are clamped or tied to the supports 57. The draw wires 53 also serve as electrical leads for the lights 45, as indicated by FIG. 4. The draw wires are shown connected to a battery 44 in FIG. 1 adjacent the viewing end of the borescope 21, to supply electrical power for the bulbs 45.

An arm 59 having a roller 61 on its outer end is secured to the forward end of the largest diameter of the cylinders 37 of the head assembly 35. The arm 59 is hinged to fold back against the largest cylinder during storage, and is provided with a locking pin 63 (see FIG. 2) to hold it perpendicular to the optical axis 48 when in use. The roller 61 maintains contact with the outer portion of the internal side wall of the bore 23 and guides the telescoping head assembly 35 around a bend 25 in the bore and into inspecting position.

The fixed angle portion 33 is a skewed housing of square cross-section, the forward end of which bolts to the rear end of the telescoping head assembly 35. It contains a Hat mirror 65 (see FIG. mounted at a fixed angle to the optical axis 48. The flat mirror 65 picks up the image from the conical mirror 47 (FIG. 2) and relays it toward the viewing end. The specific internal angle of the portion 33 is predetermined so as to fit the needs of positioning the telescoping assembly 35. A variety of such angle portions may be provided for selection as needs arise. A short tubular piece 95 is secured to the rear end of the fixed angle portion 33 and serves as a spacer which can be easily bolted to the adjacent adjustable hinge 31.

The adjustable hinge portion 31 consists of two

housings

67 and 69 of square cross-section which are ball bearing mounted, top and bottom, on a common vertical shaft 71, as illustrated by FIGS. 2 and 7. The design shown permits the forward housing 67 to rotate laterally from a position to the right to 94 to the left of the optical axis 48. As shown by FIGS. 7 and 10, a spiral spring 73 arrangement located at the bottom of the vertical shaft 71 exerts a continuous clockwise torque against the forward housing 67. By this manner, the guide arm roller 61 located on the end of the telescoping assembly 35 will be kept in continuous contact with the inner surface of the bore at a turn, when the borescope is inserted for inspection.

A flat mirror 75 (see FIG. 7) is mounted vertically inside the adjustable hinge portion 31 on the hinge shaft 71. A lever arm 77 (see FIG. 2) is fixed to the hinge shaft 71, and a spring 79 extending between the arm 77 and a mount 81 spring loads the forward housing 67 for clockwise rotation. A draw wire 83 of steel metal chord extends from the distal end of the arm 77 and leads back to the viewing end whereby the shaft 71 and the mirror 75 rigidly attached thereto can be angularly positioned by an operator. The mirror 75 is adjusted angularly for relaying the internal surface image back to the viewing end. The mirror may be locked in the desired position by a clamp 129 (see FIG. 3) on the draw wire 83 at the rear support.

A length of flexible tubing 85 runs across the top of the hinged portion from a front port 87, see FIGS. 2 and 6, in the forward hinge section 67 to a rear port 89, see FIG. 3, in the front end of the tubular barrel 29. The tubing 85 carries the gas for expanding the telescoping assembly 35 past the hinge joint 31. As indicated in FIG. 2, a pair of

transparent windows

91 and 92 seals off the open hinged joint 31. One window 92 is at the forward end of the tubular barrel 29 and the other window 91 is at the forward end of housing 67.

Along the length of the tubular barrel 29 is bolted (see FIG. 3) an intermediate flange 97 to which is bolted a three legged spider structure 99 for supporting and guiding the borescope 21 along the bore. As shown by FIG. 8, three

arms

101, 102, and 103 located 120 apart are hinged for folding against the main tubular barrel 29 to permit insertion through small diameter entrances. The

left legs

101 and 102 are detented and fixed by locking pins to hold them in their extended position of to the optical axis during the borescope 21 operation. The right leg 103 is longer than the other two and is provided with springs 109, 111 (see FIG. 9) that will hold it either in a folded position or pressed at an acute angle against the bore surface. This floating action accommodates for any irregularities or sag in the bore surfaces. The ends of the fixed

legs

101 and 102 are equipped with

rollers

113, 115 but may be equipped with skids (not shown) for traversing bellows. The spring loaded leg 103 is equipped most of the time with a roller 1 17.

The spider structure has a large elongated opening 119, see FIG. 8, so it may be positioned at different locations relative to the bore axis. This is desirable in order to eliminate interference between the side of the curve 25 in the bore, and the hinge assembly 31.

A conventional telescope 27, see FIG. 3, which serves as the eyepiece assembly is mounted in the rear I end of the tubular barrel 29 for magnifying the image reflected back through the mirror system.

The tubular barrel 29 is supported at the open end of the bore by a rear support plate 131 which is shown in FIGS. 3 and 11. Attached to the forward face of plate 131 is a short cylinder sleeve 125 through which the tubular barrel 29 fits. An end flange 127 extending from the short cylinder 125 has a plurality of screws 123 to secure it rigidly to the rear support plate.

Rear support plate 131 is triangular in shape with two extending

arms

133 and 135. Each arm has

several bolt holes

137 and 139 so that the support plate 131 can be attached to different sizes of pipe flanges 141 (FIGS. 1 and 3) whose bores are to be inspected. The plate 131 has an elongated opening 143 whereby the tubular section 21 may be positioned in a manner similar to that previously described concerning spider structure 99.

On the front side of the plate 131 are three trunicated cone shaped

buttons

145, 147 and 149 spaced angularly apart, which are used for positioning the center of plate 131 at the center of the bore entrance. Each

button

145, 147 and 149 has two or more radial positions to accommodate the different diameters of bore openings.

Slidably attached to the rear face of plate 131 (see FIG. 11) is a clamping assembly 150 consisting of a split circular clamp ring 151 and two extending

arms

152 and 153. Two

slots

154 and 155 are provided in the outer ends of

arms

152 and 153 respectively.

Bolts

156 and 157 engage the slots so that the clamping assembly 150 is attached to the support plate 131 in a manner that it may move transversely but not rotationally. This is necessary so that the center of the clamp ring 151 may coincide with the longitudinal axis of tubular barrel 29 when it is positioned at different locations relative to the bore axis. When telescoping head 35 is extended during inspection of bore surface 23 the diameter of ring 151 may be reduced by tightening screw 158 so that it is frictionally engaged with the outside surface of the tubular barrel 29. This will resist the torque imposed by the offset position of telescoping head 35 relative to the longitudinal axis of tubular barrel 29.

OPERATION In operation, the plate 131 is bolted to the flanges 141 at the entrance of the bore, usually a pipe, and the borescope 21 is fed into the bore by sliding the main tubular barrel 29 through the short cylinder sleeve 125. The telescoping head 35 is moved to the far end of the straight pipe run and moved through the pipe turn 25 until lined up with the axis of the bore surface 23. The telescoping head 35 is expanded by gas pressure introduced through inlet 51 and the bore surface inspected, through the viewing telescope 27, as the telescoping head 35 is retracted by pulling on the draw wires 53. Adjustable hinge portion 31 and fixed angle portion 33 are removed and the after end of telescoping head 35 attached to the forward end of tubular barrel 29. The straight pipe run is then inspected by slowly sliding main tubular barrel 27 until telescoping head 35 reaches pipe bend 25.

It is'now apparent that a novel borescope 21 has been disclosed. Obviously, many modifications and variations of the borescope are possible. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced other than as specifically described.

What is claimed is:

l. A borescope comprising:

a tubular barrel having forward and rear ends,

a telescoping head assembly secured to the forward end of said barrel,

said telescoping head assembly having a plurality of telescoping cylinders, said cylinders having different sizes extending from a large diameter to a small diameter and being able to slide on each other from a nested position to an extended position in which said cylinder having a small diameter is positioned most forwardly,

optical means attached to the forward end of said cylinder having a small diameter for transmitting an image of the surface area of the bore to be inspected adjacent said cylinder having a small diameter,

said optical means sealing the forward end of said cylinder having a small diameter,

means for introducing a gas into said telescoping head assembly so as to cause said telescoping c linders to slide forward! to a ro'ected osition, dra lines extending from s id op fic'lal meaiis to the rear of said barrel so that said telescoping cylinders may be retracted from its extended position to its nested position by pulling on said lines,

viewing means on the rear end of said barrel for an operator to see said image from said optical means.

2. A borescope according to claim 1 including:

an adjustable hinge joint position between said telescoping head and said tubular barrel for positioning said telescoping head about a turn in a bore to be inspected,

said hinge joint comprises forward and rear housings on a common shaft, and mirror means mounted on said shaft for transmitting said image from said optical means toward said viewing means.

3. A borescope according to claim 2 including:

a first transparent window sealing the rear end of said forward housing of said hinge joint, and a second transparent window sealing the forward end of said tubular barrel, and

flexible tubing means extending from said tubular barrel adjacent its forward end to said forward housing of said hinge joint adjacent but in front of said first transparent window,

said flexible tubing means allowing gas to be transmitted from said tubular barrel to said forward housing and thereby preventing any loss of gasin said adjustable joint.

4. A borescope according to claim 1 including illuminating means carried by said optical means, said illuminating means supplied with electrical power by said draw wires.

5. A borescope according to claim 1 including:

first roller means for spacing said telescoping head assembly from the bore surface and second roller means for spacing said tubular barrel from the bore surface, and

rear support plate slidably attached to the rear end of said tubular barrel, said support plate adapted to be secured to the structure forming the bore opening to assure proper alignment of said tubular barrel.

6. A borescope according to claim 1 including:

a fixed angle portion secured between said telescoping head assembly and said adjustable hinge joint portion, and

a flat mirror within said fixed angle portion for transmitting the image from said optical means to said adjustable hinge joint portion.

Claims

1. A borescope comprising: a tubular barrel having forward and rear ends, a telescoping head assembly secured to the forward end of said barrel, said telescoping head assembly having a plurality of telescoping cylinders, said cylinders having different sizes extending from a large diameter to a small diameter and being able to slide on each other from a nested position to an extended position in which said cylinder having a small diameter is positioned most forwardly, optical means attached to the forward end of said cylinder having a small diameter for transmitting an image of the surface area of the bore to be inspected adjacent said cylinder having a small diameter, said optical means sealing the forward end of said cylinder having a small diameter, means for introducing a gas into said telescoping head assembly so as to cause said telescoping cylinders to slide forwardly to a projected position, draw lines extending from said optical means to the rear of said barrel so that said telescoping cylinders may be retracted from its extended position to its nested position by pulling on said lines, viewing means on the rear end of said barrel for an operator to see said image from said optical means.

2. A borescope according to claim 1 including: an adjustable hinge joint position between said telescoping head and said tubular barrel for positioning said telescoping head about a turn in a bore to be inspected, said hinge joint comprises forward and rear housings on a common shaft, and mirror means mounted on said shaft for transmitting said image from said optical means toward said viewing means.

3. A borescope according to claim 2 including: a first transparent window sealing the rear end of said forward housing of said hinge joint, and a second transparent window sealing the forward end of said tubular barrel, and flexible tubing means extending from said tubular barrel adjacent its forward end to said forward housing of said hinge joint adjacent but in front of said first transparent window, said flexible tubing means allowing gas to be transmitted from said tubular barrel to said forward housing and thereby preventing any loss of gas in said adjustable joint.

5. A borescope according to claim 1 including: first roller means for spacing said telescoping head assembly from the bore surface and second roller means for spacing said tubular barrel from the bore surface, and rear support plate slidably attached to the rear end of said tubular barrel, said support plate adapted to be secured to the structure forming the bore opening to assure proper alignment of said tubular barrel.

6. A borescope according to claim 1 including: a fixed angle portion secured between said telescoping head assembly and said adjustable hinge joint portion, and a flat mirror within said fixed angle portion for transmitting the image from said optical means to said adjustable hinge joint portion.