GB2554891A

GB2554891A - Improvements in or relating to digging implements

Info

Publication number: GB2554891A
Application number: GB1617306.4A
Authority: GB
Inventors: Higgins Samir
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-10-12
Filing date: 2016-10-12
Publication date: 2018-04-18
Also published as: GB201617306D0

Abstract

A hand-held digging tool such as a spade or trowel has a detector comprising a sensor and electrical circuitry, and a signal generator. The sensor may be mounted on the blade with a cover that is secured to the blade of the digging tool. The detector may be sensitive to electromagnetic fields, capacitance changes or metal objects.

Description

(54) Title of the Invention: Improvements in or relating to digging implements Abstract Title: Digging tool with sensor and signal generator (57) A hand-held digging tool such as a spade or trowel has a detector comprising a sensor and electrical circuitry, and a signal generator. The sensor may be mounted on the blade with a cover that is secured to the blade of the digging tool. The detector may be sensitive to electromagnetic fields, capacitance changes or metal objects.

Fig. I

Fig. I

-1Improvements in or relating to digging implements

This invention relates to implements for digging into the ground and is concerned with such implements which are hand-held. Such implements comprising a shaft having first and second ends and having a handle at the first end and a blade at the second end for pushing into the ground as a result of pressure applied to the handle are well known and typical examples are spades and shovels. The blade of the implement generally needs to be as thin as possible and have a cutting edge as sharp as possible in order to facilitate it being pushed into the ground.

It is frequently necessary to use such implements to dig into areas of ground which might include electricity cables or pipes for gas or water which are buried in the ground but whose locations are not known precisely. In such circumstances there is a possibility of the cutting edge of the implement blade damaging the cable or pipe thereby causing disruption of the electricity, gas or water supply and possible injury to or death of the person using the implement.

With a view to reducing this possibility of damage, injury or death it is known to provide the blade with a thickened portion extending along the length of its cutting edge so that it is less sharp and hence less likely to damage a cable or pipe. However, the presence of this thickened portion makes it more difficult for the person using the implement to push the blade into the ground with the result that it takes longer for the digging operation to be completed. Also, the user becomes more fatigued and there is the risk of long term ligament and soft tissue damage to the hand, wrist and shoulder of the user.

It is an object of the present invention to reduce the possibility of damage, injury or death without the above-mentioned disadvantages.

According to the present invention there is provided a hand-held implement for digging the ground comprising a shaft having first and second ends and having a handle at the first end and, at the second end, a blade having a cutting edge for pushing into the ground as a result of

-2pressure applied to the handle wherein the implement includes a detector comprising a sensor and electrical circuitry connecting the sensor to a signal generating device whereby the detector produces a signal when the sensor is in the vicinity of an object in the ground to which the detector is sensitive.

Generally, the detector comprises a sensor located in the vicinity of the cutting edge of the blade and electrically connected to the signal generating device such as a light bulb or buzzer or vibrator mounted on die shaft. The sensor and the part of the electrical connection adjacent thereto may be mounted on the surface of the blade and be protected by a covering member strong enough to withstand the forces generated during the digging action. Alternatively the sensor and said part of the electrical connection may be incorporated inside the blade in, for example, a groove provided in the surface of the blade in which case the groove may, for example, extend along the centre line of the blade or be in the form of a loop. Again, they may be protected from the forces generated during the digging action by a strong covering member.

In a particularly preferred embodiment of the invention, the detector is a non-contact voltage tester of the type known as a volt testing pen. Such detectors are sensitive to cables carrying electric current. In this case the sensor of the detector and the electrical circuitry are of the type used in volt testing pens. Generally the sensor is in the form of an antenna located at the cutting edge of the blade and the electrical circuitry includes a battery operated amplifier. In use of the implement, when the antenna is in the vicinity of a cable carrying electric current buried in the ground, the detector is sensitive to the electromagnetic field around the cable and causes the signal generator to produce a signal by the bulb lighting up or die buzzer emitting a noise or the vibrator starting to vibrate as the case may be thereby alerting the user of the implement to the fact that an electric cable is nearby.

In an alternative embodiment of the invention, the detector operates in the same maimer as does a stud detector. Stud detectors are known per se and are used for locating studs, cables etc. inside walls. Materials of different density have different dielectric constants and stud detectors are sensitive to changes in capacitance caused by differences in dielectric constant. Thus, in this embodiment, the detector sensor and the electrical circuitry are of the type used

-3in stud detectors. The detector emits a signal when the sensor is in the vicinity of an object such as an electrical cable or a metal or plastics pipe carrying gas or water buried in the ground because of its different capacitance value compared to that of the ground being dug. In a further embodiment of the invention, the detector operates in the same manner as a metal detector. Metal detectors are known per se and are sensitive to metallic objects. In this embodiment the detector sensor and the electrical circuitry are of the type used in metal detectors. The detector emits a signal when the sensor is in the vicinity of a metallic object such as a metal gas or water pipe buried in the ground. In die case of this embodiment the blade of the digging implement needs to be formed of a material other than metal.

If desired, the digging implement may include more than one detector of different types so that it produces a signal when in the vicinity of different objects. Also, for the further protection of the user in the event that the detector becomes faulty and fails to give a signal when the blade is near a live electric cable, the handle may be electrically insulated from the blade.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which :Figure 1 is a plan view of a digging implement in accordance with the present invention, Figure 2 is a cross section, on an enlarged scale, through the implement of Figure 1 along the line X -X, and

Figure 3 is a diagrammatic representation of electrical circuitry included in the implement of Figures 1 and 2.

Referring now to the drawings, the digging implement is a spade in the form of a Newcastle trenching tool and comprises a shaft 1 having a blade 2 at one end and a handle 3 at a second end. The blade has a cutting edge 4. Mounted on the surface of the blade, along its centre line, is a member 5 forming a channel 6 to accommodate a sensor 7 in the form of a wire antenna terminating at the cutting edge 4. The member 5 is welded to the blade surface and is formed of a material sufficiently strong to protect the sensor 7 when the blade is driven into the ground during digging. The covering member 5 is designed to have as small a crosssection as possible so as to minimise its resistance to being pushed into the ground in use of

-4the digging implement Mounted on the shaft 1 near to the handle 3 is a housing 8. The housing accommodates a detector comprising electrical circuitry including a battery 9, an amplifier and a signal generating device 10 as shown schematically in Figure 3. The amplifier comprises two transistors 11 and 12 linked together and resistors 13 and 14 and the circuitry includes a switch 15. The sensor 7 is electrically connected to transistor 11.

In use of the digging implement, the user turns on the circuitry by means of the switch 15 and then grasps the handle 3 and pushes the blade 2 into the ground in the normal way. If the ground includes a buried cable carrying alternating current, the current generates a changing electromagnetic field in the vicinity of the cable to which the detector is sensitive. When the blade 2 approaches the cable, die electromagnetic field induces a current in the sensor 7 which is amplified by the amplifier and causes the signal generating device 10 to produce a signal to alert the user to the presence of the cable.

Claims

1. A hand-held implement for digging the ground comprising a shaft having first and second ends and having a handle at the first end and, at the second end, a blade having a cutting edge for pushing into the ground as a result of pressure applied to the handle wherein the implement includes a detector comprising a sensor and electrical circuitry connecting the sensor to a signal generating device whereby the detector produces a signal when the sensor is in the vicinity of an object in the ground to which the detector is sensitive.

2. A hand-held implement as claimed in Claim 1 wherein the sensor is mounted on the surface of the blade and is protected by a covering member secured to the blade.

3. A hand-held implement as claimed in Claim 1 or 2 wherein the sensor is in the form of an antenna located at the cutting edge and it, and the electrical circuitry, are of the type used in a volt testing pen whereby the detector is sensitive to an electromagnetic field produced by the object.

4. A hand-held implement as claimed in Claim 1 or 2 wherein the sensor and the electrical circuitry are of the type used in a stud detector whereby the detector is sensitive to capacitance changes caused by the object.

5. A hand-held implement as claimed in Claim 1 or 2 wherein the sensor and the electrical circuitry are of the type used in a metal detector whereby the detector is sensitive to the object when it is formed of metal.

6. A hand-held implement substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

Intellectual

Property

Office

Mr Ralph Plowman

29 March 2017

GB1617306.4

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