Patent US3907136A successfully refreshed from Google Patents.
US3907136A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System for preventing digging machine from damaging underground conduits
Assignee: Individual
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Filing: 1973-12-26
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Granted: 1975-09-23
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Expires: 1993-12-26
Abstract
Abstract A transmitter produces an oscillating electric signal in the region where a digging tool is working, and the signal is powerful enough to induce a small current in any electrically conductive conduit buried in the region. Several sensor inductors are mounted on the digging tool and oriented so that an electromagnetic field around the conduit created by the induced current in the conduit induces a voltage in the sensor inductors as the tool approaches the conduit. A proximity signal is produced for each sensor inductor as a function of the respective induced voltages, the proximity signals are compared, and an output signal is produced whenever the proximity signals differ by a predetermined factor indicating approach of the tool to the buried conduit. The output signal is used to warn the operator or stop the machine.
Inventors
- 👤 Lee S Christides
- 👤 Harry L Jensen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 22:27
CPC Classifications
E; E02; E02F; E02F3/00; E02F3/04; E02F3/28; E02F3/36; E02F3/42; E02F3/427; E02F3/30; E02F3/32; E02F9/00; E02F9/24; E02F9/245; G; G01; G01V; G01V3/00; G01V3/08; G01V3/10; G01V3/104; Y; Y10; Y10S; Y10S37/00; Y10S37/906
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
300 words
A system for preventing a digging tool of a digging machine from damaging an underground conduit buried in a region where said tool is digging, said conduit having an electrically conductive path either from electrical conductivity of said conduit itself or from an electric conductor buried with said conduit to aid in detecting said conduit, said system comprising: a. transmitter means for producing an oscillating current in said electrically conductive path; b. a plurality of sensor inductors mounted on said digging tool in the region of a digging edge of said tool and oriented so that an electromagnetic field around said conductive path created by said induced current in said conductive path induces a voltage in said sensor inductors as said tool approaches said conductive path in any practical working orientation; c. means responsive to each of said sensor inductors for producing a proximity signal relative to each of said sensor inductors as a function of the respective one of said voltages for each of said sensor inductors; d. means for comparing said proximity signals; e. means for producing an output signal whenever said proximity signals differ by a predetermined factor indicating approach of said tool to said buried conduit; f. a reference inductor is mounted on said digging tool remotely spaced for said digging edge of said tool and oriented so that any ambient noise induces a voltage in said reference inductor, but said electromagnetic field created by said induced current in said buried conduit does not induce a detectable voltage in said reference inductor as said tool approaches said conduit in any practical working orientation; and g. means for subtracting said voltage induced in said reference inductor from said respective voltages induced in said sensor inductors to obtain said proximity signals relative to each of said sensor inductors.
Claim 2
Independent Claim
300 words
A system for preventing a digging tool of a digging machine from damaging an underground conduit buried in a region where said tool is digging, said conduit having an electrically conductive path either from electrical conductivity of said conduit itself or from an electric conductor buried with said conduit to aid in detecting said conduit, said system comprising: a. transmitter means for producing an oscillating current in said electrically conductive path; b. a plurality of sensor inductors mounted on said digging tool in the region of a digging edge of said tool and oriented so that an electromagnetic field around said conductive path created by said induced current in said conductive path induces a voltage in said sensor inductors as said tool approaches said conductive path in any practical working orientation; c. means responsive to each of said sensor inductors for producing a proximity signal relative to each of said sensor inductors as a function of the respective one of said voltages for each of said sensor inductors; d. means for comparing said proximity signals; e. means for producing an output signal whenever said proximity signals differ by a predetermined factor indicating approach of said tool to said buried conduit; f. a reference inductor is mounted on said digging tool remotely spaced for said digging edge of said tool and oriented so that any ambient noise induces a voltage in said reference inductor, but said electromagnetic field created by said induced current in said buried conduit does not induce a detectable voltage in said reference inductor as said tool approaches said conduit in any practical working orientation; and g. means for subtracting said voltage induced in said reference inductor from said respective voltages induced in said sensor inductors to obtain said proximity signals relative to each of said sensor inductors.
Claim 3
Dependent Claim
15 words
The system of claim 1 wherein said sensor inductors are recessed into said digging tool.
Claim 4
Dependent Claim
29 words
The system of claim 2 wherein said machine is a backhoe, said digging tool is a backhoe bucket having teeth, and said sensor inductors are recessed into said teeth.
Claim 5
Dependent Claim
26 words
The system of claim 1 including means for warning an operator of said machine, and means responsive to said output signal for actuating said warning means.
Claim 6
Dependent Claim
25 words
The system of claim 1 including means for automatically stopping said machine, and means responsive to said output signal for actuating said machine stopping means.
Claim 7
Dependent Claim
34 words
The system of claim 5 wherein said machine includes Hyraulic circuitry, and said machine stopping means includes a solenoid-operated valve in said hydraulic circuitry for stopping said digging tool upon operation of said valve.
Claim 8
Dependent Claim
35 words
The system of claim 1 wherein said transmitter means produces an oscillating electromagnetic field in said digging region, and said transmitted electromagnetic field is powerful enough to induce said current in said electrically conductive path.
Claim 9
Dependent Claim
37 words
The system of claim 1 wherein said transmitter means produces a difference of electrical potential across said digging region, and said difference in said electrical potential is sufficent to produce said current in said electrically conductive path.
Claim 10
Dependent Claim
93 words
The system of claim 1 wherein one group of said sensor inductors are spaced horizontally along said digging edge of said tool, and another group of said sensor inductors are spaced along a perpendicular to said horizontally spaced sensor inductors, and said comparing means compares said proximity signals from said one group of said sensor inductors and compares said proximity signals from said other group of said sensor inductors, and said output signal producing means produces said output signal whenever either of said comparisons of said proximity signals differ by said predetermined factor.
Claim 11
Dependent Claim
46 words
The system of claim 9 including a pair of said reference inductors, one of said reference inductors having the orientation of said one group of horizontally spaced sensor inductors, and another one of said reference inductors having the orientation of said other group of sensor inductors.
Claim 12
Dependent Claim
46 words
The system of claim 10 wherein said subtracting means subtracts the output of said one reference inductor from each of said sensor inductors of said one group and subtracts the output of said other reference inductor from each of said sensor inductors of said other group.
Claim 13
Dependent Claim
35 words
The system of claim 11 wherein said transmitter means produces an oscillating electromagnetic field in said digging region, and said transmitted electromagnetic field is powerful enough to induce said current in said electrically conductive path.
Claim 14
Dependent Claim
37 words
The system of claim 11 wherein said transmitter means produces a difference of electrical potential across said digging region, and said difference in said electrical potential is sufficent to produce said current in said electrically conductive path.
Claim 15
Dependent Claim
15 words
The system of claim 11 wherein said sensor inductors are recessed into said digging tool.
Claim 16
Dependent Claim
49 words
The system of claim 14 wherein said machine is a backhoe, said digging tool is a backhoe bucket having teeth, and said one group of said sensor inductors are recessed into said teeth, and said other group of said sensor inductors are mounted on the sides of said bucket.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-22 | 1979-03-24 | 1979-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-22 | 1983-03-24 | 1983-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-22 | 1987-03-24 | 1987-09-23 | $7700.00 | Window Closed / Lapsed |