FR2838998A1 - Security feature for motorised cutting tools, comprises two electrical conductors which are insulated from each other and included in the anvil blade such that a metallised glove makes a connection - Google Patents

Abstract

A motorised (3) cutting tool has blades (2A,2B) and is used with metallised gloves. The anvil blade is fabricated as two electrical conductors (22A,23A) which are insulated (24) from each other. If the glove comes into contact with the conductors a circuit is made and the action of the blades is stopped and even reversed

Description

perforations (7).

  SAFETY DEVICE FOR CUTTING TOOLS OR

  CUTTING EDGE, SECURE SECTOR AND CIRCUIT OF

PROTECTION FOR SUCH TOOLS.

  The present invention relates to a safety device for cutting or cutting tools, a secure secateur and a protection circuit for such tools. Wile relates to all cutting or cutting tools in which the start-up and stop of the wind is carried out electrically, the source of energy actuating the organs of

  cutting may be other than electric and, for example pneumatic or hydraulic.

  Motorized cutting or cutting tools, for example electric secateurs, have a motor which actuates the clamping of two blades or a blade and a support, under the manual control of the user. Their cutting capacity is such that the user can cut a finger by accident. Although professionals, who commonly use this kind of tools in viticulture, generally put gloves on

  metal mesh, the risk of accident by pinching or cutting remains important.

  We know devices, such as ccux present in US documents, 669,809 and WO 0996625, in which the gent is provided with an emitter of electrical signals which pass through the metallic meshes of the glove. When the gent touches one of the secateurs blades, the signal is transmitted to a receiver which interrupts the action of

blade clamping.

  Such devices have many drawbacks. First, the gent and the expensive wind secateurs. Then, the gent must be provided with an electric power supply (cells or batteries) and in case the reserve of electric energy of the gent is exhausted, the user

  is no longer protected. In addition, such gloves are fragile and heavy.

  Other systems propose to connect the glove, by an electrical conductor, to a secateur detector so that any electrical contact between the gent and a secateur blade is detected by the detector and causes the action to stop. blade clamping. The electrical conductor which connects the gent to the pruner in these devices interferes

  the user in his movements so that few professionals use it.

  The present invention aims to remedy these drawbacks.

  To this end, the present invention relates to a cutting tool comprising two cutting members (blade and hook), at least one of these cutting members being moved, relative to the other cutting member, by a motor with electric control, for clamping and cutting a part placed between these cutting members, characterized in that: - the two members jointly carry at least two isolated electrical conductors between them, - the cutting tool comprises at least one electrical contact between the isolated electrical conductors, and an electrical protection circuit connected to said detector and to the electrical control of the motor and adapted to interrupt the tightening movement

  cutting members when an electrical contact is detected by said detector.

  Thanks to these provisions, say that an electrically conductive wire or a metal protected gent is tightened between the two cutting members, the detector detects it and the tightening is interrupted. The user is therefore safe whatever the type of metal protection gent he uses. Likewise, if he is helped by another person wearing this type of glove, that other person is also protected. Finally, if a metal part is tightened between the cutting members, safety prevents this metal part or the cutting members from being damaged. In the case of a pneumatic secateur, a solenoid valve is controlled when an electrical contact is detected by the detector to interrupt the tightening movement or reverse it. In the case of a pruning shears comprising an electric motor in direct contact with the cutting members, the electric motor is stopped or its direction of rotation is reversed when an electric contact is detected by said detector. According to particular characteristics, the electrical protection circuit comprises a fusible overcurrent protection element sensitive to the detection of electrical contact between the isolated electrical conductors. Thanks to these provisions, the electrical protection circuit and, more generally, the wind cutting tool is

simple and inexpensive implementation.

  According to particular characteristics, the electrical protection circuit is adapted to cause the cutting members to move apart when an electrical contact is detected by said detector. Thanks to these provisions, the possible tightening of the wire or the electrically conductive wire is immediately released when the electrical contact is detected, which improves the safety of the user and reduces his pain compared to a

  simple stop of the tightening movement.

  According to particular characteristics, the electrical control comprises an electrical contactor actuated manually by the user to generate an activation signal from the reception of which a power circuit controlled by the electrical control supplies driving energy to an actuating motor member. of the cutting elements of the cutting tool, the release of the contactor causing the emission by the electric control of a deactivation signal from the reception of which the power circuit stops or reverses the clamping movement of the cutting elements , the detector comprising a comparator circuit which compares the value of a reference electrical voltage applied to one of its two input terminals, to the value of the electrical voltage applied on the one hand to the cutting members and, on the other hand, on its other input terminal, said comparator by its output terminal being electrically connected to the electrical control and supplying it with a s default fault when a potential difference appears between its input terminals, this potential difference being due to an electrical contact between the isolated electrical conductors, the reception of the

  fault signal generating ['sending of a deactivation signal by the command.

  electric from the reception of which the power circuit cuts the supply of the

1 5 motor.

  Thanks to these provisions, no fusible element is destroyed during closing

of the protection circuit.

  According to particular characteristics, the electrical protection circuit is adapted to connect the terminals of the electrical control of the motor to each other when the electrical protection circuit is closed. Thanks to these provisions, the cessation of the movement

is almost instantaneous.

  According to particular characteristics, the cutting tool comprises an adapted reactivation circuit, after an electrical contact has been detected by said detector, at

  again allow the electric control of the cutting member tightening.

  According to particular characteristics, the electric control comprises an electric contactor activated manually and the reactivation circuit reactivates the electric tightening control after a predetermined number of manual presses on

said electrical contactor.

  According to particular characteristics, the protection circuit comprises a threshold for detecting electrical contact between the insulated electrical conductors carried by the cutting members, threshold below, from which the interruption of the tightening command is not carried out. Thus, the presence of moisture on the cutting members does not cause untimely detection. Other advantages, aims and characteristics of the present invention will emerge from

  the description which follows, made for explanatory purposes with regard to the accompanying drawings

  in which: - Figure 1 represents a general view of a cutting tool such as a pruning shears according to the invention comprising a safety device according to the invention, - Figure 2A represents, in section, a first embodiment of a cutting tool such as a secateur according to the invention comprising a safety device according to the invention, FIG. 2B represents, in a section perpendicular to the section illustrated in FIG. 2A, the first embodiment of a cutting tool like a pruner according to the invention comprising a safety device according to the invention, FIG. 2C, in perspective and in section, a cutting member of the first embodiment of a cutting tool such as a pruner according to the invention comprising a safety device according to the invention, - Figure 3, in section, represents a second embodiment of a cutting tool such as a pruning shears according to the invention comprising a safety device according to the invention, - the figure 4, in section, represents a third embodiment of a cutting tool such as a pruning shears according to the invention comprising a safety device according to the invention, FIG. 5 schematically represents a first embodiment of an electrical protection circuit of a cutting device protection according to the invention, FIG. 6 diagrammatically represents a second embodiment of an electrical protection circuit of a protection device according to the invention, and FIG. 7 diagrammatically represents a third embodiment of a

  electrical protection circuit of a protection device according to the invention.

  As represented in FIGS. 1 to 4, the cutting tool 1, such as, for example, a motorized pruner includes cutting members 2A and 2B in the form of cutting blades (the word "blade" also covering the concept of hook) actuated by a motor member 3, from the actuation of a contactor 4 provided on the tool 1. The action on the

  contactor 4 ensures the connection of the drive member 3 to an energy source 5.

  Without being limiting, the motor member 3 illustrated here is a direct current electric motor and the energy source 5 is in the form of electric batteries. These batteries, as shown in Figure 1, wind housed in a sheath under

  form of belt that the user wears at the waist.

  It can be observed that, as a variant, the drive member 3 is pneumatic or hydraulic and

  includes a solenoid valve (not shown).

  The cutting tool 1 comprises an electrical protection circuit 21A, 21B or 21C.

  In the first embodiment, illustrated in FIGS. 2A to 2C, the electrical protection circuit 21A comprises at least two electrically conductive elements 22A and

  23A doors by the cutting member 2A and isolated from each other by an insulating piece 24.

  In the second embodiment, illustrated in FIG. 3, the electrical protection circuit 21B comprises at least, carried by each of the cutting members 2A and 2B, at

  at least one electrically conductive element 22B and 23B.

  In the third embodiment, illustrated in FIG. 4, the electrical protection circuit 21C comprises, on at least one of the cutting members, two elements

  conductors 22C and 23C which alternate alternately on the cutting line.

  Preferably, the electrical conductive elements wind adapted not to be in electrical contact when the wind cutters in contact, at the end of tightening, thanks to a choice of morphology of the electrical conductors. For example, it can be seen in FIG. 2C that the electrical conductor 22A exceeds, on the cutting member 2A, the electrical conductor 23A and is therefore the only one to come into contact with the cutting member 2B. The circuit illustrated in FIG. 5 is represented opposite the first embodiment, illustrated in FIGS. 1 to 2B. However, it easily adapts to other embodiments, illustrated in FIGS. 3 and 4, in accordance with the positioning of the elements.

  drivers of these other embodiments.

  An electrically conductive element 6 is intended to cover the anatomical area to be protected of the body of the user (or of another user, for example an assistant). The electrical protection circuit illustrated in FIG. 5 comprises: - a source of electrical voltage 7, - a first electrical connection between the positive pole, for example, of the voltage source 7 and the conductive element 22A and - a second electrical connection between the other pole of the voltage source 7 and the conductive element 23A, possibly via the cutting member 2A and the carcass of the tool 1, said carcass advantageously being made of metal, an electrical connection between the cutting blades and the carcass being established either by construction or by fitting an electrical conductor. The electrical connection between the positive pole of the electrical voltage source 7 and the conductive element 22A is provided by an electrical cable 8, isolated from the elements

  electrically connected to the conductive element 23A.

  The voltage source 7 can be constituted by an accumulator or equivalent, by a voltage divider bridge supplied by the electric power source 5, or by any other

  other means known to those skilled in the art.

  The electrically conductive elements 22A and 23A, the cutting blade 2A, the conductive element 6, the voltage source 7 and the electrical connections form the electrical protection circuit 21A (respectively 21B or 21C) which closes when the electrical contact is established between the conducting elements 22A (respectively 22B, 22C) and 23A (respectively 23B and 23C). The protection circuit closes in particular when the conductive element 6 or a metallic piece (for example a metallic wire) forms contact between these conductive elements, that is to say when the use of the tool 1 becomes dangerous. for the user or for a metal installation, for example trellising wires. This electrical protection circuit remains open so that the electrically conductive elements are moved away from the conductive element 6 and therefore from the area

  anatomical or metallic installation to be protected.

  On one of the connections between the voltage source 7 and the conductive elements 22A and 23A is a detector 9 for contact between the conductive elements, also called "sensitive means" when the electrical protection circuit is closed, this means 9 being sensitive to the effect of the electric current flowing in the electrical protection circuit after closing. In the embodiment illustrated in FIGS. 2A to 2C, when the electrical contact is established between the conductive elements 22A and 23A, and an electric current flows in the electrical circuit 21A, the sensitive means 9 opens or controls the opening of the control and / or supply circuit between the motor 3 and the energy source 5, which causes at least the immediate stopping of the cutting movement of the

  blades one with respect to the other and possibly setting them apart.

  Thus, according to variants of the present invention: - the contact between the conductive elements causes the cutting movement to stop, - the contact between the conductive elements causes the blades to separate, the contact between the conductive elements causes the separation blades and the safety of the cutting tool, it must be restarted to be able to make a new cut, or - contact between the conductive elements causes the blades to move apart and the cutting tool to standby, a predetermined number (for example trots) of manual actuations of contactor 4 being necessary to be able to carry out a

new haircut.

  The electrically conductive element 6 is flexible and constitutes, according to the preferred embodiment, a clothing item that the user puts on the anatomical area to be protected. This element 6 can therefore be pants, a jacket or a item as shown in the accompanying drawings. This gent 6 can be entirely metallic and be in the form of a mesh side or else made of a woven material, electrically conductive. We can still foresee a gent in skin covered with a

electrically conductive screening.

  In the first embodiment of an electrical protection circuit 21A, illustrated in FIG. 5, the voltage source 7 is constituted by the energy source 5 and on the electrical connection between the energy source 5 and the member or 2A cutting blade, wind

  arranged in series with the contactor 4 and the means 9 sensitive to the closing of the circuit 21A.

  According to this embodiment, this means 9 is constituted by a fusible element for protection against overcurrents, with rapid response, which ensures almost

  instantaneous opening of the electric supply circuit of the electric motor 3.

  With reference to FIG. 6, a second embodiment of the object of the invention is now exposed. The cutting tool 1 for which this second embodiment is provided comprises a control circuit 10 provided with the contactor 4, from the action on which said control circuit 10 generates an activation signal applied to the input for controlling a power circuit 11, so that the latter supplies electrical power to the motor unit 3 of the electric pruner 1. The release of the contactor 4 causes the control circuit 10 to emit a deactivation signal from the reception of which the power circuit cuts the supply

  of the motor or [reversing the direction of movement of the blades.

  The power circuit 11 is known to those skilled in the art and is not described in detail. Essentially, this power circuit 11 is constituted by a transistor which can be on or off depending on the high logic state or teas of its base, this logic state being determined by the on or off state of a transistor 12 on the base from which the control signal is applied. This control signal depending on its level

  logic is either the activation signal or the deactivation signal.

  The control circuit is also known to those skilled in the art and essentially comprises two flip-flops D identified by 13 and 14, in FIG. 6, one of which, flip-flop 13, is associated with contactor 4. The respective outputs of these flip-flops are electrically connected to two inputs of a NAND gate 15 whose output is connected to the two inputs of a second NAND gate 16 playing the role of inverter. At the output of this second NAND gate 16 is available the control signal, this signal, depending on its

  logic level, which can be the activation signal or the deactivation signal.

  The control circuit as described is electrically connected to the output of the

  means 9 sensitive to the closing of the protection circuit.

  This means 9 is. for example, a comparator circuit which compares the value of a reference electrical voltage applied to one of its two input terminals, to the value of the electrical voltage applied on the one hand to the cutting members 2A and 2B and on the other hand on its auke entrance terminal. According to this exemplary embodiment, the value of the reference voltage is zero, the corresponding terminal of the comparator being connected to ground. The comparator, by its output terminal, is electrically connected to the control circuit 10 and, more precisely, at the input of the second flip-flop 14 to deliver a fault signal to the control circuit when a potential difference appears between its input terminals, this potential difference being due to the closure of the protection circuit by electrical contact between the electrically conductive element 6 or any other metallic object and at least the cutting members 2 of the tool 1. The reception of the fault signal generated ['the emission of a deactivation signal by the control circuit from the reception of which the power circuit cuts the power supply to the motor 3 or reverses the direction of movement of the blades, to remove them. More precisely, the second flip-flop 14, when it receives the fault signal at its input, modifies the logic state of its output and therefore of the corresponding input of the first NAND gate 15 so that the output state of each of doors 15 and 16 is modified, if and

  only if contactor 4 is actuated.

  It is necessary, of the electric deactivation of the electric motor 3, to ensure a quick stop of the latter. To this end, an electronic switch 17 is provided, comprising a control input by which it receives the deactivation signal, said controller being connected to the input terminals of the word eur 3 to form in the cities. terminals an electrical circuit first open, in the absence of the activation signal and then closed when the deactivation signal is applied to the control input, the closing of this circuit connecting the two to each other terminals of the electric motor 3 which dissipates the electric energy remaining in the motor. In addition, the mechanical movement transmission between the output shaft of the motor 3 and the cutting blades 2A and 2B has a significant reduction ratio and the importance of the moving masses is low, so that the cutting blades 2A and 2B and the transmission members cannot, by inertia, entrain the output shaft of the motor 3. Thus, the stopping of the movement of the output shaft of the motor 3, causes by the connection one to one other of the two terminals of the motor 3, immediately stops the cutting movement of the

blades 2A and 2B.

  According to the preferred embodiment, the electronic switch is a transistor connected by its emitter and its collector to the two terminals of the electric motor 3, this transistor can be either blocked or conducting, depending on the voltage level

  electric applied to its base, which constitutes the control input.

  In FIG. 6, it can be noted that at the input of the control circuit is connected the output of a circuit 18 for detecting short circuits, this circuit 18, as soon as a short circuit is detected, delivering to the input of flip-flop 14 a fault signal. This circuit 18 essentially comprises an operational amplifier 18A operating in

  comparator, on one of the input terminals to which a reference voltage is applied.

  The other input terminal is connected to the negative terminal of the DC motor 3.

  It is understood that this circuit operates in the same way, with the means 9 previously described, so that, according to a simplified form of the invention, this circuit constitutes this means 9. For this purpose, the electrically conductive element 22 is connected to the positive terminal of the motor and the negative terminal is connected to the element electrically

  conductor 23. The positive terminal of the motor is connected to the power circuit 11.

  Other embodiments may be provided for the means 9 sensitive to the closing of the protection circuit and this is how this means may be constituted by an opto-coupler whose [emitter element will be serially on one of the two links

  electrical components of the protection circuit.

  Finally, a circuit 19 for detecting blockage of the blades 2A and 2B may be added to the secateurs. This circuit, when this fault is detected, applying to the input of the circuit.

  command, a fault signal from which the engine stop is controlled.

  FIG. 7 shows a third embodiment of an electrical protection circuit of a protection device according to the invention. This electrical protection circuit implements an analog signal according to four possible levels: - high level corresponds to a disconnected secateur, - high intermediate level corresponds to a reverse gear (blade spacing), - intermediate level teas corresponds to a forward gear ( approximation of the blades), and

  - level teas correspond to a limit stop.

  The high intermediate and teas wind levels obtained by the resistance poems R1 / R2, for the high intermediate level, and R1IR3, for the intermediate teas level,

  according to the state of analog switches U1A and U1C.

  The simultaneous switching of the two analog switches U1A and U1C depends on the "all or nothing" signal, depending on the cited resistance of "pull up" R5, supplied by the Hall effect sensor of the trigger H4 (or manual electrical contactor 4 in the other figures). When the H4 trigger is released, the high intermediate level is provided, to indicate a reverse command. When the trigger is pressed, the

  intermediate level teas is provided, to indicate a forward command.

  The signal is put in the teas state (stop detection) by the Hall effect sensors H1, H2 and H3 located at the extreme points of the pruning stroke. Each stop has an effect only on the direction of movement of the blades which allows it to be reached and has no effect on

the other direction of movement.

  The "safety" signal, received on the J3 connector, inactive in the high state is pulled at the teas level (pruning shears) when a metallic object establishes a contact between the safety wire included in the blade and the metallic casing. of the secateur (the electrical mass of the electronics of the control ribbon cable is connected to the metal box by screws fixing the ribbon cable). For added security, the security wire included in the blade is connected by two separate wires to terminals J3. 1 and J3.2 (which makes it possible to detect a

  accidental cut of one of these wires).

  The level of sensitivity of the detection of a metallic contact is limited by the value of the resistance R6. Thus, the presence of moisture on the cutting members does not

  does not cause untimely detection.

  When the safety signal becomes active, the analog switch U1B switches and forces the level switches U1A and U1C in trigger released state and

  therefore causes the blades to move apart.

  In addition, the switch U1B combined with the pressed state of the trigger (U4 active) makes it possible to maintain (memory effect) the security effect even if the security signal is passed. Thus, in the event of security detection, even fugitive, the pruning shears can only make an opening movement up to the opening stop, any closing movement can only occur after the cause of the security detection and trigger release. According to a variant not shown, the protection circuit includes a counter of successive calls on the trigger, any movement of closing of the cutting members being able to occur only after disappearance of the cause of detection

  safety and a predetermined number of presses on the trigger (for example trots).

  It is observed that, as a variant, at least part of the analog connections can

  be replaced by digital links managed by microprocessor (not shown).

  It goes without saying that the present invention can receive all arrangements and variants in the field of technical equivalences without departing from the scope of the

present patent.

Claims (8)

  1 - Cutting tool (1) comprising two cutting members (2A, 2B), at least one of these cutting members being moved, relative to the other cutting member, - by a motor (3) a electric control (4, 10, H4), for clamping and cutting a piece placed between these cutting members, characterized in that: - the two members carry, at the same time, at least two isolated electrical conductors between them (22A, 23A, 22B , 23B, 22C, 23C), - the cutting tool comprises at least one electrical contact detector (9, 10) between the isolated electrical conductors, and an electrical protection circuit (21A, 21B, 21C) connected to said detector and to the electrical control of the motor and adapted to interrupt the clamping movement of the cutting members when an electrical contact is detected by said detector.   2 - Cutting tool according to claim 1, characterized in that at least one of the two cutting members (2A) carries at least two of said electrical conductors (22A, 23A) isolate them.   3 - Cutting tool according to claim 2, characterized in that said electrical conductors (22A, 23A) wind doors parallel to the length of said cutting member.   4 - Cutting tool according to claim 2, characterized in that said electrical conductors (22C, 23C) are alternately flush on a cutting line said cutting member.   - Cutting tool according to claim 1, characterized in that each of said cutting members (2A, 2B) carries at least one of said electrical conductors (22B, 23B) isolate them.   6 - Cutting tool according to any one of claims 1 to 5, characterized in   that the electrical protection circuit (21A, 21B, 21C) includes a fusible overcurrent protection element sensitive to the detection of electrical contact between the insulated electrical conductors.   7 - Cutting tool according to any one of claims 1 to 6, characterized in that the electrical protection circuit (21A, 21B, 21C) is adapted to cause the separation of the cutting members when a contact electric is detected by said detector (9, 10).   8 - Cutting tool according to any one of claims 1 to 6, characterized in that the electrical control comprises an electrical contactor (4) actuated manually by the user to generate an activation signal from the reception of which a power circuit (11) controlled by the control circuit (10) supplies driving energy to a motor member (3) for actuating the cutting members (2A, 2B) of the cutting tool (1), the release of the contactor (4) causing the emission by the electric control (10) of a deactivation signal from the reception of which the power circuit (11) stops or reverses the cutting movement of the cutting members, the detector comprising a comparator circuit which compares the value of a reference electrical voltage applied to one of its two input terminals, to the value of the electrical voltage applied on the one hand to the cutting members and, on the other hand, on its other input terminal, said comparator by s with an output terminal being electrically connected to the electrical control and providing it with a fault signal when a potential difference appears between its input terminals, this potential difference being due to an electrical contact between the isolated electrical conductors, the reception of the fault signal generating [emission of a deactivation signal by the electric control from the reception of which the power circuit modifies the power supply to the motor.  9 - Cutting tool according to any one of claims 1 to 8, characterized in that the electrical protection circuit (21A, 21B, 21C) is adapted to connect the terminals of the electric motor control ( 3) when the electrical circuit of protection is firm.   - Cutting tool according to any one of claims 1 to 9, characterized in   that the cutting tool comprises a reactivation circuit (U 1 B) adapted, after an electrical contact has been detected by said detector (9, 10), to again allow the electric control of the clamping of the cutting members (2A , 2B), the electric control comprising an electric contactor activated manually and the reactivation circuit reactivating the electric tightening control after a predetermined number of presses