WO2008102225A2

WO2008102225A2 - Device for sensing electric hazards

Info

Publication number: WO2008102225A2
Application number: PCT/IB2008/000306
Authority: WO
Inventors: Patrizio Criconia
Original assignee: Ruspelli, Giancarlo
Priority date: 2007-02-21
Filing date: 2008-02-12
Publication date: 2008-08-28
Also published as: WO2008102225A3; ITPI20070015A1

Abstract

A safety device against the risk of accidental electric contact between a machine (1) for yards or for handling material or the like and an electric cable under voltage (3), comprising a sensor (7) for sensing the electric field or electromagnetic, located in at least one predetermined point of the machine on a zone of end or on an arm (12), and an emergency device comprising means for blocking the displacement of the machine when the machine reaches a predetermined critical distance of danger from the electric cable under voltage, and/or warning means (9) of proximity associated with the sensors (7), capable of emitting a warning signal that informs the operator at reaching a critical danger position and at approaching to the critical distance.

Description

TITLE

DEVICE FOR SENSING ELECTRIC HAZARDS DESCRIPTION

Field of the invention

The present invention relates to the field of industrial safety, in particular in yards, or when handling loads and, more precisely, it relates to a system to avoid the risk of contact with electric cables under voltage near zones of operativity of construction machines, or transportation machines, or in general machines during their action.

Description of the technical problem

In the field of constructions and of manipulation and displacement of loads, it is often necessary the use of machines for construction works, for displacement of materials, and for digging of various nature such as a bulldozer, a crane, an excavator, a lift, etc.

In fact, on the one hand bulldozers and excavators of different size and power are commonly used for making bases and foundations in the ground for constructions, or excavations in general. On the other hand, machines generally with lifting arms are instead used for displacing heavy loads from a point to another. Other similar machines with support platforms at an end of the arm allow to an operators to reach high working zones for carrying out aerial maintenance operations.

Presently, in case of presence of cables under electric voltage near working zones where the above described machines operate, the only safety requirement is a minimum distance defined by safety rules. However the operators of the machines do not always respect such distance for reasons that can be of different nature.

In fact, even when the cables under electric voltage are well visible, in any case a distraction of the operator or a wrong manoeuvre may occur passing the minimum safety distance and contacting the cable under electric voltage. This risk is particularly high during work with aerial platforms or in case of manoeuvres of fixed or mobile cranes.

In case of electric contact between such machines and electric cables, on the one hand, very serious consequences for the persons may arise and cause even the death of the operator for electrocution. On the other hand the electric systems of the machine can damage with the subsequent impossibility of operating the machine same that can therefore cause serious damages to the persons. In less serious cases for the persons, nonetheless, major damages to the machine may occur.

In the case, instead, where the machine is an excavator or the like, it is not possible to see a buried cable before discovering it.

Also in the case, moreover, where the machine comprises a platform movable moved by a mechanical arm formed by many links, this machine can meet an electric cable under voltage hidden by a tree, by a mast, or by a wall, since part of the trajectory followed by the platform may not be visible to the operator.

Summary of the invention

It is therefore a feature of the present invention to provide a safety system for machines for yards or for handling material or the like, adapted to avoid with efficiency and simplcity the contact with or the approaching movements to an electric cable under voltage, visible or hidden.

A further feature of the invention is to provide a safety system for machines for yards or for handling material or the like, capable of blocking such machines when they come at a critical distance from said electric cables under voltage.

These and other features are accomplished with one exemplary safety device against the risk of electric contact between a machine for yards or for handling material or the like and an electric cable under voltage, whose characteristic is that it comprises:

- at least one electric or electromagnetic field sensor located in at least one predetermined point of said machine;

- at least one emergency device associated with said machine, said at least one sensor being connected to said at least one emergency device causing said emergency device to turn on responsive to value of said electric or electromagnetic fields defined by said sensor with respect to predetermined threshold values.

Preferably, the emergency device is selected from the group comprised of:

- means for blocking said machine when said machine reaches a predetermined critical distance of danger from said electric cable under voltage,

- proximity warning means, associated with said at least one sensor, capable of emitting a warning signal for an operator, informing from of entrance in a critical dangerous region;

- a combination thereof.

This way, such a safety device prevents from an accidental contact between a machine and an electric cable under voltage, also when the operator cannot see, from the actual position, where the electric cable under voltage is located.

In particular, said machine for yards or for handling material or the like has at least one mechanical arm consisting of one or more links.

Advantageously, said machine for yards or for handling material or the like is selected from the group comprised of:

- an excavator or a bulldozer;

- an auger;

- a mobile platform;

- a crane;

- a lift;

- a hoist;

- a rescue means having a motor ladder;

- a betonpump;

- an apparatus for carrying loose material.

In particular, said at least one predetermined point of said machine belongs to at least one element of said machine, selected from the group comprised of:

- a mechanical arm;

- a tool of excavation;

- a gripping tool or a hook; .

- a mobile platform;

- any end portion of said machine.

In particular, said warning signal is of at least one type selected from the group comprised of:

- acoustic;

- bright or visible;

- a vibration.

In particular, said proximity warning means are adapted to emit a warning signal that is of variable intensity proportional to the actual distance between said machine and said electric cable under voltage. This warning signal allows the user to become aware of the approaching movement after having passed a threshold critical value with respect to the electric cable.

Alternatively, said proximity warning means are adapted to emit a bright or visual signal generated by an alphanumerical display capable of providing an actual intensity value of the electromagnetic field generated by said electric cable under voltage.

In a possible exemplary embodiment, said proximity warning means are arranged remotely in a fixed or mobile position. This way it is possible to control the distance and to work in a safe place, so that working safely with the machine for the operator. Furthermore, the possibility of controlling the distance allows also to manoeuvre the above described machine even only remotely, thus avoiding to put in danger an operator that works locally.

Advantageously, said at least one sensor and said proximity warning means and/or said means for blocking are connected to each other in a way selected from the group comprised of:

- by electric connecting cables;

- by transmission of electromagnetic signals without connecting cables.

According to another aspect of the invention, a method to avoid the risk of electric contact between a machine for yards, or for handling materal, , or the like, and an electric cable under voltage, comprises the steps of:

- arranging at least one electric or electromagnetic field sensor located in at least one predetermined point of said machine;

- connecting said sensor to means for blocking said machine, associated with said at least one sensor, capable of blocking said machine when it reaches a predetermined critical distance of danger from said electric cable under voltage;

- connecting said sensor to proximity warning means, associated with said at least one sensor, capable of emitting a warning signal towards an operator, when entering a critically dangerous region; said at least one sensor sensing the intensity of the electric or electromagnetic field emitted from said electric cables, sending a signal of activation of said blocking and/or warning means for values of the electric or electromagnetic field above predetermined critical threshold values.

Brief description of the drawings.

The invention is now shown with the following description of two of its embodiments, exemplifying but not limitative, with reference to the attached drawings, in which like reference characters designate the same or the like parts, throughout the figures of which:

- Figure 1 shows a perspective view of an aerial platform for in a suspended position according to the state of the art;

- Figure 2 shows a perspective view of a second type of construction machine according to the state of the art;

- Figures 3 and 4 show a perspective view of an aerial platform having a safety device according to the present invention;

- Figure 5 shows a perspective view of a construction machine having a safety device according to the present invention;

- Figure 6 shows an example of application of the safety device according to the invention to a means for handling material having a gripping arm and handling a suspended load;

- Figure 7 shows a diagrammatical logical scheme of operation of the invention.

Description of preferred exemplary embodiments In figure 1 a typical situation is shown of a very frequent risk, in a case, for example, where works are made with aerial platforms. The operator acts in the safety fence 2 arranged on the arm of platform 1.

If an operator works near electric cables under voltage 3, another operator manoeuvring the platform has to keep the platform at a minimum safety distance 4 from the cable. However different factors such as distraction, wrong evaluation of the distance or other, can determinate an accidental contact of the machine or the operator with the electric cables. Furthermore, the platform may be positioned correctly, keeping a minimum safety distance, but the operator above the platform, when working, may cause the platform to rotate or displace in a zone located underneath, hand in case of low visibility, risking to contact the cable (not shown) from the actual position of the operator.

In figure 2, instead, a typical situation is shown of excavating machines. In the specific case, only for example and in a way therefore not limitative for the present invention, the problematic has been shown relative to a kind of auger 5. Of course another desired type of similar machine for handling material or for excavation may meet the same problem.

In these cases, there is not any possibility for an operator to determine possible cables under voltage located under ground. It is therefore completely inefficient to respect possible safety rules such as the minimum operativity distance, with possibility of very risky situation.

In figure 3 the inventive concept according to the present invention is diagrammatically shown adapted to solve the above described problems. A sensor for detecting electric or electromagnetic fields 7 can be arranged, for _ p _ example, just at the safety fence 8 where the operator is located. The radius of action of sensor 7 has been diagrammatically shown as 10 with radial sensitivity. The intensity of electric or electromagnetic field sensed by sensor 7 changes according to the distance at which it is located with respect to the cables under voltage 3 during the operativity of the machine. When, therefore, the intensity detected by sensor 7 increases or passes a minimum predetermined safety threshold, sensor 7 emits a signal to safety devices 9. This occurs by emitting for example lights or sirens as normal alarm systems immediately informing of a danger and allowing the operator to block the machine.

Alternatively, it is possible to connect the safety sensor 7 not only with acoustic devices, but also with systems for blocking instantaneously the machine. These systems for blocking the machine are activated also as the signal is received by sensor 7, as already described. The ways of blocking the machine can be of various nature, for example electric or mechanical, and are not described in more detail since detectable without difficulty by a skilled person.

It is also possible, as shown in figure 4, to position more sensors in potentially dangerous points of the machine, in a way suitable to cover an optimal field of action. In particular, in the case of figure 4 different positions have been shown of arm 12 of the machine and of safety fence 2 of the machine. Another desired arrangement can be done in a way not limitative for the present invention, depending on industrial reasons and on the type of machine.

In figure 5 is instead shown a typical case where operations of excavation and the like are carried out. In the specific case of figure 5, but in any case not limitative for the present invention, the example of an auger 13 has been shown. In this case, it is possible, for example, to set sensor 7 just at pneumatic cylinder 15 on which the drill tip 16 is mounted. Even in this case, sensor 7 senses the intensity of the electric or electromagnetic field emitted by the cables under voltage 3, operating therefore the same safety systems 9 or +blocking the machine when it reaches or passes a threshold of minimum safety.

Also in this case it is possible to set more sensors in different points of the machine, according to the needs. In case of deep excavations it is even possible the introduction of the sensor in the drill bit.

In figure 6 a possible application is shown of the safety device according to the invention to a means for handling material 6 having an arm 12 gripping and handling a suspended load, ending with a hook 18. In this case, more sensors 7 can be distributed at critical points of the machine, for example on the hook 18, and on intermediate elements of the arm 12. Even in this case means can be provided for warning an operator and blocking them.

In figure 7 a logical cycle is diagrammatically shown of operation of the system. The beginning cycle of operation of the sensor is shown with the "Start". In this phase a receiving step of the signal of the electromagnetic field emitted by the cables under voltage is carried out. If the intensity is under the predetermined threshold, then any signalling or blocking the machine is carried out and the cycle starts again normally. Vice-versa a high threshold of the signal causes the block or turning on warning systems.

The foregoing description of a specific embodiment will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt for various applications such an embodiment without further research and without parting from the invention, and it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiment. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Claims

L. A safety device against the risk of electric contact between a machine for yards or for handling material or the like and an electric cable under voltage, characterised in that it comprises :

- at least one emergency device associated with said machine, said at least one sensor being connected to said at least one emergency device causing said emergency device to turn on responsive to values of said electric or electromagnetic fields defined by said sensor with respect to predetermined threshold values.

2. A safety device, according to claim 1, wherein said emergency device is selected from the group comprised of:

- means for blocking said machine when said machine reaches a predetermined critical distance of danger from said electric cable under voltage;

- proximity warning means, associated with said at least one sensor, capable of emitting a warning signal towards an operator, informing about entrance in a critical dangerous region;

- a combination thereof.

3. A safety device, according to claim 1, wherein said machine for yards or for handling material or the like has at least one mechanical arm consisting of one or more links.

4. A safety device, according to claim 1, wherein said machine for yards or for handling material or the like is selected from the group comprised of: - an excavator or a bulldozer;

- an auger;

- a mobile platform;

- a crane;

- a lift;

- a hoist;

- a rescue means having a motor ladder;

- a betonpump;

- An apparatus for carrying loose material.

5. A safety device, according to claim 1, wherein said at least one predetermined point of said machine belongs to at least one element of said machine, selected from the group comprised of:

- a mechanical arm;

- a tool of excavation;

- a gripping tool or a hook;

- a mobile platform;

- any end portion of said machine.

6. A safety device, according to claim 2, wherein said warning signal is of at least one type selected from the group comprised of:

- acoustic;

- bright or visible;

- a vibration.

7. A safety device, according to claim 2, wherein said proximity warning means are adapted to emit a warning signal that is of variable intensity proportional to the actual distance between said machine and said electric cable under voltage.

8. A safety device, according to claim 2, wherein said proximity warning means are adapted to emit a bright or visual signal generated by an alphanumerical display capable of providing an actual intensity value of the electromagnetic field generated by said electric cable under voltage.

9. A safety device, according to claim 2, wherein said proximity warning means are arranged remotely in a fixed or mobile position.

10. A safety device, according to claim 1, wherein said at least one sensor and said at least one emergency device are connected to each other in a way selected from the group comprised of:

- by electric connecting cables;

- by transmission of electromagnetic signals without connecting cables.

11. A method to avoid the risk of electric contact between a machine for yards or for handling material or the like and an electric cable under voltage, comprising the steps of:

- connecting said sensor to proximity warning means, associated with said at least one sensor, capable of emitting a warning signal towards an operator, when entering a critically dangerous region; characterised in that: said at least one sensor detects the intensity of the electric or electromagnetic field emitted from said electric cables, sending a signal of activation of said blocking and/or warning means for values of the electric or electromagnetic field above predetermined critical threshold values.