Electricity: measuring and testing – Of geophysical surface or subsurface in situ – For small object detection or location
Patent
1991-02-07
1992-09-22
Wieder, Kenneth A.
Electricity: measuring and testing
Of geophysical surface or subsurface in situ
For small object detection or location
32420714, 32420726, 324226, G01B 731
Patent
active
051500566
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method and device for locating branches in drains, notably to a method and device for locating the axis of the branch so that a hole registering with the branch can be cut in a lining within the main drain from which the branch drain leads.
BACKGROUND TO THE INVENTION
Many drains and sewers (hereinafter generally termed drains) were constructed many years ago and the wall structures are now badly eroded or collapsing. In order to repair such damage, it has been proposed to insert a liner within the drain to provide a new water-impervious wall to the drain. However, the wall of the drain is often not continuous since branch drains debouch into the main drain through an entry port in the wall of the main drain. Where a liner is installed, it is necessary to cut an aperture in the liner wall in register with this entry port to allow the free flow of fluid from the branch drain into the main drain.
It has been proposed to locate the entry points for the branch drains by visual survey of the drain before the liner is installed and then to cut the apertures after the liner has been installed by running a suitable cutting machine along the drain for the required distance. However, since most liners are opaque or metallic, the accurate register of the cutting tool with the actual entry port of the branch cannot be achieved visually and dead reckoning measurement has to suffice.
The branch drain often enters the main drain at an angle so that the axis of the branch is not normal to the axis of the main drain. This further complicates the accurate registry of the cutting tool with the actual entry port of the branch drain.
I have now devised a method and apparatus which reduces the above problems.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a method for locating the longitudinal axis of a branch pipe from a main pipe, which method comprises mounting a magnetic field emitter in the branch pipe so that it radiates magnetic lines of force along the branch pipe and into the main pipe, and locating the axis of the branch pipe by detecting the primary line of the magnetic flux emitted from the emitter by means of a location device moveable within the main pipe.
The term "primary" is used herein in relation to the lines of flux emitted from the emitter to denote that line which is substantially straight. Typically this line coincides with the axis of the emitter and hence of the branch pipe in which the emitter is mounted.
The magnetic field emitter can be one which emits a pulsed or varying magnetic field, for example one which emits a magnetic field in response to a driving oscillator circuit; or can be one which emits a substantially constant continuous signal, as when a permanent magnet is mounted axially within the branch pipe. Depending upon the type of magnetic field emitter used, it may be desirable to shape the field by the use of suitable shaping means so as to provide a directional magnetic field emission directed axially along the branch pipe.
Depending upon the type of field being emitted, the sensor within the main pipe can be selected from a static coil type detector, a balanced induction loop type detector or a Hall effect sensor.
The method of the invention is of especial use where the main drain has a liner therein and it is desired to locate a cutting tool in register with the entry port of the branch drain so as to cut a suitable aperture in the wall of the lining. Whilst a pulsed or varying magnetic field emitter can be used satisfactorily where a non-metallic lining is used, such emitters are not wholly suitable for use with metallic wall liners or with liners made from a material which significantly attenuates or distorts a pulsed magnetic field. Such liners may so affect the signal emitted from a pulsed signal emitter in the branch pipe that accurate location of the axis of the branch pipe is not possible. I have found that the use of a constant magnetic field emitter can often overcome these problems. The invention therefore also pro
REFERENCES:
patent: 2521745 (1950-09-01), Pope
patent: 3027951 (1962-04-01), Knapp et al.
patent: 3406766 (1968-10-01), Henderson
patent: 3495626 (1970-02-01), Nagel
patent: 3704413 (1972-11-01), Blevins
patent: 3878453 (1975-04-01), Potter et al.
patent: 3906504 (1975-09-01), Guster et al.
patent: 4205266 (1980-05-01), Lichtenberg
patent: 4223228 (1980-09-01), Kaplan
patent: 4371836 (1983-02-01), Nickel et al.
patent: 4631477 (1986-12-01), Nickel et al.
Edmonds Warren S.
Gunter Jr. Charles D.
Wieder Kenneth A.
LandOfFree
Method and device for locating the longitudinal axis of a branch does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for locating the longitudinal axis of a branch, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for locating the longitudinal axis of a branch will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1071541