Abstract:
The pipeline leak detection and repair device is an autonomous machine that travels through a pipeline to detect very small leaks therein. The device also repairs those leaks with an on-board repair component. The repair occurs nearly simultaneously with the leak detection as the device passes the leak. The device includes a plurality of thin, flexible sensor leaves in a radial array. The leaves are positioned to place them nearly in contact with the inner surface of the pipe wall. Each leaf includes two sensors installed on its opposite surfaces. Flexure of the leaf due to changes in pressure gradient as the leaf passes a leak results in signals from the sensors being sent to an onboard processor. The processor determines the position of the affected leaf, and rotates a repair component to apply a pressure-sensitive tape patch over the leak as the repair component passes the leak.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to autonomous robotic mechanisms, and particularly to a pipeline leak detection and repair device. The device travels through a fluid pipeline (e.g., water, gas, oil, etc.), detects small leaks, and repairs those leaks automatically. 
     2. Description of the Related Art 
     Fluid leakage from pipelines, e.g., gas, oil, and water, is a chronic problem in the industry. The financial losses resulting from fluid loss can be significant, depending upon the value of the fluid and the size of the leak, among other factors. Moreover, many pipeline leaks occur in low pressure lines, with contamination leaking into the pipe rather than outward from the pipe. This is a major concern in the case of potable water, as even a very small leak can contaminate a water supply with bacteria or other hazards. In other cases, the fluid carried in the pipeline may be hazardous to the environment (e.g., oil), and leakage from the pipe can contaminate a large area if the leak continues for some period of time. 
     Most pipeline leak detection devices and systems are adapted for the detection of relatively large leaks, as the financial loss and potential hazards are generally proportional to the leakage volume per unit of time. These large leak detection devices are incapable of detecting relatively small leaks, and in the case of water pipelines such small water leaks are generally neglected. However, numerous small leaks can result in a significant loss of fluid over an extended period of time, and a corresponding financial loss. Perhaps the most common principle of leak detection is the acoustic method, in which a highly sensitive acoustic detector searches for the change in acoustic signal clue to fluid passing through a small leak or disruption in the pipe. However, many older pipes are being replaced with plastic (polyvinyl chloride, or PVC) pipe, and such acoustic sensors generally do not work well in such plastic pipe. 
     One universal symptom of a pipeline leak is the change in pressure gradient of the fluid near the leak. The change in pressure gradient is generally not readily detectable near the center of the flow through the pipe, except in the case of very large leaks. Accordingly, most leak detection devices are incapable of detecting very small leaks and seepage, as noted further above. Moreover, even where such very small leaks and seeps may be detected, these devices do nothing to stop the leak. Leak stoppage must be performed by a separate operation after detection of the leak. 
     Thus, a pipeline leak detection and repair device solving the aforementioned problems is desired. 
     SUMMARY OF THE INVENTION 
     The pipeline leak detection and repair device is an autonomous machine that travels within a fluid pipeline, and that simultaneously detects and repairs small leaks and seeps in the pipeline wall. The device is supported by forward and rearward wheels extending from multiple arms disposed in a radial array. At least one of the wheels may be powered to provide active motion. Alternatively, the device may be carried through the pipeline by the fluid flowing in the line. 
     The forward end of the device includes a plurality of sensor leaves disposed in a radial array. The circular diameter defined by the sensor leaves is adjusted to position the leaves immediately adjacent to the interior of the pipe wall. Each sensor leaf is formed of a very thin and flexible sheet of material (metal, plastic, etc.) and includes two mutually opposed strain gauges installed on opposite surfaces of the leaf. (Other types of sensors may be used in lieu of strain gauges, e.g., pressure and/or force sensors, piezoelectric sensors, etc.) As the leaf encounters a slight fluid leak, it is drawn in the direction of fluid flow through the leak. The leaf flexure changes the output of the two strain gauges of the leaf. The signals from the strain gauges are sent to a microcontroller installed in the device. 
     The microcontroller determines which of the leaves is affected by the leak and sends a signal to rotate the repair component of the device about the longitudinal axis of the device to align the repair component with the affected leaf, thus aligning the repair component with the detected leak. The rate of travel of the device through the pipeline is determined by the rotational speed of one or more of the supporting wheels, and as the longitudinal distance between the affected sensor leaf and the repair component is known, the elapsed time from leak detection to arrival of the repair component at the leak may be determined. 
     The repair component is activated when it arrives at the leak detected by the sensor leaf at the front of the device. The repair component comprises a plurality of pressure-sensitive, flexible adhesive patches carried on a flexible release sheet tape. The tape is carried on a roll in the repair component. The tape passes over a roller at the outer end of an adjustably extendable arm. Used tape is collected on a takeup roller within the repair component. As the repair component reaches the leak, the arm is extended to press the tape against the inner surface of the pipe wall using the roller at the end of the arm. One or more of the pressure-sensitive adhesive patches adheres to the inner surface of the pipe wall and releases from the release sheet, thereby sealing the leak as the device passes. The location of the leak and patch may be recorded in an on-board electronic memory. 
     These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an environmental side elevation view in section of a pipeline leak detection and repair device according to the present invention, shown within a pipeline. 
         FIG. 2  is an end elevation view of the pipeline leak detection and repair device of  FIG. 1 , showing the arrangement of the leak detection sensors. 
         FIG. 3  is another end elevation view in section of the pipeline leak detection and repair device of  FIG. 1 , showing the rearward support wheel assembly. 
         FIG. 4A  is a side elevation view in section of the patch dispensing mechanism of a pipeline leak detection and repair device according to the present invention, showing the applicator arm in its retracted state. 
         FIG. 4B  is a side elevation view in section of the patch dispensing mechanism of the pipeline leak detection and repair device similar to  FIG. 4A , but showing the applicator arm in its extended state for applying a patch over a leak. 
     
    
    
     Similar reference characters denote corresponding features consistently throughout the attached drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The pipeline leak detection and repair device is a completely autonomous machine that is capable of traveling through a gas, oil, water, or other pipeline to detect small leaks therein. Moreover, the device automatically seals those leaks nearly simultaneously as it passes them. The only delay is the very short time span between the detection of the leak at the front of the device and the sealing of the leak by the mechanism toward the rearward portion of the device as the device travels through the pipeline. 
       FIG. 1  of the drawings provides a schematic side elevation view of the pipeline leak detection and repair device  10 , shown traveling through a pipeline P. The device  10  comprises substantially identical front and rear supports  12  joined by an axial connecting column  14 . The only difference between the two supports is their relative locations and the installation of a drive motor to drive at least one of the wheels on one of the supports, as discussed further below. 
     Each support  12  comprises a central support hub  16  having a plurality of arms  18  extending radially therefrom, as shown in  FIG. 3 . Three such arms  18  are preferably provided, as the distal ends  20  of the three arms serve to center the supports  12  within the pipe P when the lengths of the arms are adjusted to fit closely within the pipe P. A wheel  22  is installed on the distal end  20  of each of the arms. The wheels  22  roll along the interior wall of the pipe P as the device  10  travels through the pipe. Conventional suspension springs (not shown) may be provided between the distal ends  20  of the arms and the wheels  22  to position the wheels securely upon the inner surface of the pipe P. While the device  10  may be carried passively through the pipe P by the fluid flow within the pipe, a motor  24  may be installed upon one of the arms  18  to drive the corresponding wheel  22 , as shown in  FIG. 3 . Power for the motor  24  may be provided by an on-board battery  26  or the like, through a cable or harness  28 . More such motors may be installed upon other arms to drive other wheels, but a single drive motor and driven wheel is sufficient in most circumstances to move the device  10  through a pipe containing a stationary fluid or against the flow of fluid within the pipe. 
     A leak sensor mechanism  30  is installed forward of the front support  12 , as shown in  FIG. 1  of the drawings. The mechanism  30  is shown in the front view of  FIG. 2  as well. The mechanism  30  comprises a leak sensor column  32  extending forward from the front support  12 . The column  32  has a forward end  34  having a leak sensor support ring  36  installed thereon. The leak sensor support ring  36  has a circular configuration of predetermined diameter in order to fit reasonably closely within the pipe P, with a slight gap or space between the periphery of the ring  36  and the interior of the pipe P. The support ring  36  includes a plurality of flow passages  38  therethrough in order to allow fluid in the pipe P to flow through and past the device  10 . Similarly, the spaced apart radially disposed arms  18  of the two supports  12  define flow passages  40  therebetween, as shown in  FIG. 3  of the drawings. 
     A plurality of flexible leak detector leaves  42  extend radially outward from the periphery of the ring  36 . Each leaf  42  has a relatively large circumferential span and a relatively small clearance or gap between adjacent leaves in order to provide substantially complete coverage of the area adjacent to the wall of the pipe P. Each leaf  42  has a forwardly disposed surface  42   a  and an opposite rearwardly disposed surface  42   b , as shown in  FIG. 1 . Strain gauges  44   a ,  44   b  are installed upon the two surfaces  42   a  and  42   b  of each of the leaves  42 . Various types or principles of pressure or force measuring gauges, piezoelectric sensors, etc., may be used in lieu of strain gauges in order to sense movement of the flexible sensor leaves  42 . 
     Any leaks in the wall of the pipe P will result in a localized pressure gradient very near the leak. This pressure gradient will result in the adjacent leaf  42  being drawn toward the outflow toward the leak, thus flexing the leaf  42  as the device  10  travels through the pipeline P. As the leaf  42  flexes, the two strain gauges  44   a  and  44   b  are affected. The strain gauges  44   a  and  44   b  communicate electrically by means of a wiring harness  46  with a microcontroller  48  located between the two supports  12 , shown schematically in  FIG. 1  of the drawings. 
     The device  10  includes a leak repair mechanism  50 , in addition to the other components described further above. The repair mechanism  50  is shown generally in  FIG. 1 , and in detail schematically in  FIGS. 4A and 4B  of the drawings. The leak repair mechanism  50  includes a base  52  that serves as a mounting location for the applicator arm  54  that applies the repair patches within the pipe. The arm  54  is pivotally installed on the base  52  by a pivot pin  56 . An actuator  58  (e.g., a solenoid) is attached to the proximal lower end of the arm  54 , opposite the distal end  60  thereof. A roller  62  is installed upon the distal end  60  of the arm  54 . 
     A tape roll  64  carries a roll of leak sealing applicator tape  66  thereon. The tape  66  comprises a release sheet having leak sealing material disposed thereon for application to the leak(s). The tape  66  extends from the roll  64 , around the roller  62  at the distal end  60  of the arm  54 , and back to a takeup roll  68  disposed with the base  52 , i.e., adjacent thereto. The leak sealing material preferably comprises a plurality of spaced-apart, pressure-sensitive adhesive patches  70  disposed in a linear array along the length of the release sheet. 
     The leak repair mechanism  50  is affixed to the central portion of the connecting column  14 . The central portion of the column  14  and the leak repair mechanism  50  rotate between the two ends of the column  14  and their forward and rearward supports  12 . A motor  72  ( FIG. 1 ) rotates the central portion of the column  14  and the leak repair mechanism  50  thereon in accordance with signals received from the microcontroller  48 . It will be seen that the relatively narrow tape  66  with its adhesive patches  70  will in most cases not be aligned longitudinally with the leak when the leak is encountered by any one of the leak detector leaves  42 . However, each of the leaves  42  is connected separately to the microcontroller  48 , and the microcontroller recognizes the relative radial position of the affected leaf  42 . The microcontroller  48  then sends a corresponding signal to the motor  72 , causing the motor to rotate the central portion of the column  14  between the two supports  12  to align the repair mechanism  50  (and especially the distal end  60  of the arm  54  with its roller  62  and repair tape  66  passing therearound) with the affected leaf  42 , and thus with the leak L, generally as shown in  FIG. 4B  of the drawings. 
     When the arm  54  and repair tape  66  have been aligned longitudinally with the leak L, the microcontroller  48  determines the time interval from the initial encounter of the leak by the affected sensor leaf  42  to the positioning of the roller  62  therebeneath according to the rate of travel of the device  10  through the pipe P and the longitudinal span between the leaves  42  and the distal end  60  of the arm  54 . The microcontroller  48  sends a signal to the arm actuator  58  to extend the arm  54  from its normally retracted position, as shown in  FIG. 4A , to its extended position, as shown in  FIG. 4B , to press the tape  66  and at least one of its pressure-sensitive adhesive patches  70  against the inner surface of the pipe P as the roller  62  passes across the leak L. It will be seen that while there is a very short time delay between the detection of the leak L and the travel of the device  10  to position a repair patch  70  across the leak, the process is very nearly simultaneous due to the very short time required for the device  10  to travel a distance equal to the short span between the sensor leaves  42  and the distal end  60  of the arm  54 . 
     The pressure of the roller  62  against the tape  66  forces one of the pressure-sensitive adhesive patches  70  against the inner surface of the pipe P and across the leak L, thereby sealing the leak as the device  10  continues to travel through the pipe. The tape  66  separates from the back of the applied patch  70  as the tape winds around the roller  62 , and is collected on the takeup roll  68 . The tape  66  is automatically drawn from its dispensing roll  64  by the capture of the applied adhesive patch  70  against the fixed wall of the pipe P, so no drive mechanism is required to dispense the tape  66 . A ratchet or sprag mechanism  74  or the like is provided to prevent any reverse movement of the tape  66  back toward the dispensing roll  64 , and to assure that a fresh portion of tape  66  with a new adhesive patch  70  is positioned properly when another leak is encountered. 
     When the leak detection and repair device  10  has completed its passage through a length of pipe P, it may be retrieved conventionally for servicing and reuse. The electrical storage battery or batteries  26  may be recharged or replaced, and the tape  66  replaced with a new series of adhesive patches  70  thereon. The device  10  may optionally be equipped with an on-board recorder (not shown). The recorder may record the travel of the device through the pipe P in accordance with rotation of one or more of the wheels  22 , and record the detection of any leaks encountered and the application of repair tape thereto. In this manner, the operators of the device  10  may retrieve a record of the location(s) of the leak(s) and their repair(s), for reference as required. Alternatively, or in addition to such on-board recording, the device  10  may include an on-board wireless communications device connected to the microcontroller  48  to communicate with a control station located outside the pipeline in order to provide real-time data regarding the location of any leaks detected, and to receive commands from the control station. 
     It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.