FR2846729A1 - Programmable protection and safety device for motorized tools controls contact between tool and user's hand or any part of body wearing protection means and stops tool motor when protection means contacts cutting object - Google Patents

Abstract

The programmable protection device (1) controls the contact between the tool (7) and the user's hand or any other part of the body wearing protection means (2) and stops the tool motor (6) when the protection means enters into contact with the cutting object. Independent claims are included for a protection glove and a method of securing a motorized tool.

Description

The subject of the present invention is a device for protecting and

  safety for users of electrically powered power tools. By electrically controlled tools is meant tools whose starting and stopping are carried out electrically, the source of energy for actuating the operational members being able to be other than electric, for example hydraulic or pneumatic. Common protection and safety devices are systems

  analog. They have operating parameters fixed during their manufacture.

  As an example of a fixed parameter, we can cite a threshold voltage or the delay between establishing a contact voltage and stopping the motor. Therefore, after manufacture, these devices can only operate with the cutting tool for which they are intended. Such an example of a protection device for a cutting tool

  is provided by patent FR-93 14129.

  The technical problem is to provide a protection device which can be used with a motorized object such as a press, a machine tool, or even a cutting tool capable of protecting any part of the body or any material part presenting a risk of deterioration. In general, this protective device must be able to be associated with a motorized tool in which stopping the engine makes it possible to reduce the risk of injury or damage to a material part to be protected. he

  this device should have high reliability and ensure maximum safety.

  The present invention eliminates the aforementioned drawbacks and solves the above-mentioned problems as well as others, by providing a protection and safety device whose operating parameters are adjustable after manufacture, thanks to the fact that the voltages applied to the protection device and of

  security are converted into digital signals.

  The invention therefore relates to a protection and safety device intended for use with a motorized tool, said device being associated with a protective means that conducts electricity and causing the actuator of the assisted tool to stop, and possibly its reversal of movement, under the action of an electrical voltage called "contact voltage" resulting from contact or proximity of contact between the tool and the protection means. According to the invention, the device comprises at least one means for converting the contact voltage into a digital signal representative of said voltage, for comparing this digital signal with a digital reference signal and for controlling the stopping of the tool motor according to the

  result of the comparison of the two digital signals.

  The digital signal assigned to the contact voltage, the digital reference signal and the signal intended to stop the tool motor can be configured, which allows this protection system to be adapted to the specific features of the various types of tools to be secured. This protection and security device controls the distance between the motorized tool and the user's hand or any other part of the body coated with a protection means, most often a chain mail type fabric. Then, this device measures the voltage designated as the contact voltage generated by the closing of an electrical circuit during contact or near contact between the motorized tool and the protection means, and causes the engine to stop. of the tool if it

  is greater than a threshold voltage.

  In particular embodiments which can be taken in isolation or in all their technically possible combinations and each having specific advantages: - the digital reference signal represents a threshold voltage, and the protection and safety device sends a stop signal to the tool motor if the contact voltage exceeds said threshold voltage; - the digital reference signal is automatically adjusted according to the maximum voltage established by contact of the protection means with the tool. This adjustment takes account of the wear and soiling of the protection and safety device. Indeed, wear and fouling will cause a decrease or variation in the electrical contact voltage. The digital reference signal representing the threshold voltage will therefore be adjusted and recorded as a function of the state of soiling and wear of the security system; the comparison between the digital signal representing the contact voltage and the reference digital signal is carried out periodically, according to an adjustable frequency; the means controlling the stopping of the tool motor also controls its reversal of movement (for example its opening according to the tool), as a function of the result of the comparison between the digital signal representing the voltage of

  contact and digital reference signal.

  This movement invention allows the protective elements to be released from the tool

  and protect possibly stuck.

  - The protection and security device further comprises a means of controlling the continuity of the connection between the protection means and said control means, this comprising a connection system (for example consisting of two wired connections 35 or a transmitter-receiver system), with the protection means and causing the engine to stop if said link is broken. This check ensures that a link is always present between the protection and security device and the protection means; this control is advantageously carried out periodically at a

adjustable frequency.

  All the functions of the protection and security device are realized

  by a single logic circuit or by separate logic circuits which are combined together.

  According to a particular embodiment, the protection means is a glove made of conductive material, in particular a glove made of chain mail fabric, associated with an under-glove made of material which is good conductor of electricity; the assembly comprising two connection means, one of said means being carried by the glove and the other by the under-glove, these connection means being electrically connected to each other by contact of the glove with the under-glove. These connection means make it possible to connect the

  glove to the protection and safety device.

  The connection means carried by the glove and the under-glove are advantageously electrically isolated from the conductive materials constituting the two gloves, and are electrically connected to said conductive materials by at least one electrical resistance. This makes it possible to prevent the tool from working if the connection means which must be connected to the protection means have been intentionally or not

directly connected to each other.

  According to another possible embodiment, the protection means is a single glove made of conductive material, and the two connection means are carried by the glove. Again, these connection means are advantageously electrically isolated from the material of which this glove is made, and are electrically connected to said glove.

  conductive material by at least one electrical resistance.

  The invention also relates to a method for securing a motorized tool

  using the device described above.

  According to the invention, the method comprises, during each powering up of the device, a step of deactivation or blocking of the tool, followed by a step of checking the continuity of the connection between the checking means and the means protection, a step of recording the digital reference signal, the tool blocking being lifted if the previous steps have been carried out successfully, and a last step repeated in loop for measuring the contact voltage and control

said bond.

  The invention will be described in more detail by way of illustration and in no way limitative with reference to particular embodiments shown in the accompanying drawings in which: - Figure 1 is a general diagram showing the protection and safety device according to the invention associated with a motorized cutting tool; - Figure 2 shows partially and in schematic form a particular embodiment of the protection and safety device according to the invention; - Figure 3 is a possible embodiment of the protection and security device according to the present invention; - Figure 4 is an overview of an exemplary embodiment of the protection means usable with the protection and safety device according to the invention - Figure 5 is a sectional view which illustrates a detail of Figure 4 ;

  - Figure 6 illustrates a detail of the protection means of Figures 4 and 5.

  Figures 1 to 6 illustrate a particular embodiment of a protection and security device according to the invention, applied to an electric pruner

  portable, intended in particular for pruning the vine.

  Although the embodiments presented are associated with a motorized cutting tool, the invention is not limited to this single application, the protection device being able to be associated with a motorized tool such as a press for example, and in general to a power tool in which stopping the engine reduces the

  risk of injury or damage to a material part to be protected.

  In the following description as well as on the drawings, and in order to bring them

  for the sake of brevity and clarity, the same reference numbers are used to

  designate identical bodies or objects of the protection and safety device.

  As shown in FIG. 1, the protection and safety device designated by the general reference 1 is associated with a cutting tool 7 actuated by a motor 6 and with a protection means 2 conducting electricity. This means of

  protection 2 covers the part to be protected by an aggressive action from the cutting tool 7.

  An electrical connection 3 provides the connection between the protection device 1 and the protection means 2; a power supply unit 4 incorporating one or more batteries is connected to the protection device 1 with the interposition of a control button 5. A connection 8 makes it possible to generate a voltage in the blade of the cutting tool 7.

  In addition, as can be seen in FIG. 2, a control means 9 is associated with the protection means 2 via two electrical connections 10 and 11, and two connection means 62 and 63, for example in the form press studs.

  According to a preferred embodiment of the invention, the control means 9 is combined with the protection device 1; in this case, link 3 is replaced by

connections 10 and 1 1.

  The two links 10 and II can be replaced by any other equivalent means, in particular a transmitter / receiver link system, for example radio

or infrared.

  FIG. 3 illustrates by way of example the arrangement of a protection device and

  security according to the invention.

  The protection and security device designated by the general reference 1 comprises a logic control circuit 12 which is an 8-bit microcontroller, having a fast operating speed of the order of 4 MHz. This microcontroller 12 is programmable and has an analog / digital converter 5. This microcontroller 12 is connected to the power supply 4 via a power circuit 32 of a type known to those skilled in the art and which will therefore not be described in more detail. The microcontroller has outputs 13 and 29, connected to the housing 17 integrating the engine control electronics 6 via a means 14 and a link 16. The means 14 includes resistors 31, 42, 43 , 44, and NPN 15 and 30 transistors. The control unit

  17 is connected to the motor 6 of the cutting tool 7 via a link 18.

  A link 8 connects the motor 6 to the blade of the cutting tool 7, which makes it possible to apply an electrical voltage to this blade. The microcontroller 12 has an input 23 capable of carrying out analog / digital conversions of the voltages 15 applied to it, as well as an output 19. The output 19 and the input 23 of the microcontroller 12 are connected by means of an electrical circuit which is composed of means 20 and 22, connection means 10 and 11 and protection means 2. The means 20 comprises a resistor 45, a diode 46 and a PNP transistor 21. The means 22 comprises a resistor 47 and a diode 48. The microcontroller 12 also has an output 24 connected to a means 25 capable of providing an audio and / or visual signal. Finally, the microcontroller has an input 28 connected to the control unit 17 by a link 26 and a means 27. The means 27 is

  composed of a diode 49 and a resistor 50.

  When the power is turned on, the microcontroller 12 immediately performs an internal reset and renders the control button for the cutting tool 7 inoperative. For

  this, the output 13 of the microcontroller 12 becomes positive and acts on the NPN transistor 15 of the means 14. This transistor 15 becomes conducting and transmits by blocking 16 to the control unit 17 of the cutting tool 7, the blocking information of the cutting tool.

  This information allows the blocking of the motor 6 thanks to the link 18. In this state 30 the tool can no longer function even if the control button is actuated.

  Following this blocking, the microcontroller 12 performs a continuity test of the connection between the protection means 2 and the microcontroller 12. To perform this test, the output 19 of the microcontroller goes low and acts on the PNP transistor 21 of the means 20. The PNP transistor 21 turns on, the protection means 2 sees a positive voltage appear which it will transmit, if the wire connections are good, at the input 23 of the microcontroller through the means 22. If the input 23 receives this positive voltage, the test is correct, output 19 goes high to block the

  transistor 21 and return to the initial state.

  If the wire connections are not good, the input 23 of the microcontroller will not receive the expected positive voltage, and the microcontroller will trigger an audible and / or visual signal via the output 24 and the means 25. If the test is correct, a signal different from the previous one sounds to indicate to the operator that he must carry out a contact test between the protection means 2 and the blade of the cutting tool 7, as an initialization of the protection device. By the connection 8, the cutting tool 7 is with a permanent positive tension. When a direct contact is established between the protective means 2 and the blade of the cutting tool 7, and thanks to the link 11, the input 23 of the microcontroller 12 will measure a positive voltage. The microcontroller 12 will then convert this voltage applied to the input 23 into a digital signal and compare this signal to a prerecorded threshold signal corresponding for example to a fraction of the voltage generated in the cutting tool 7 thanks to link 8 (this fraction being for example 2 / 5th). If it results from this comparison that the tension resulting from a frank contact is equal to at least 2 / 5th of the tension generated in the cutting tool 8 via the connection 9, the test will be considered as successful by the microcontroller 12. If the voltage from this contact is less than 2 / 5th of the voltage generated in the cutting tool 7, the contact is not correct, the microcontroller 12 will loop through this test

  until the contact between the blade of the cutting tool 7 and the protection means 2 is sufficient. If the test is successful, the microcontroller will memorize the frank contact voltage and determine by calculation the threshold voltage below which the protection device will send a motor blocking signal (this threshold voltage may for example correspond to 2 / 5th of the free contact voltage).

  When the preceding operations are completed and validated, the microcontroller passes the output 13 to the low state and no longer transmits the blocking information of the cutting tool 7, through the means 14 and the link 16; the tool is then functional. According to a programmable repetition rate, preferably less than 10 ms and during the entire closing time of the cutting tool 7, the microcontroller tests the existence of contact between the protection means 2 and the cutting tool 7. When the control button is pressed, a signal controlling the closing of the tool is emitted by the link 26 and acts on the means 27. This signal is detected by the microcontroller at its input 28. This change of state of the input 28 indicates to the microcontroller that the motor 6 is in action and that the cutting tool 7 is in movement to close. From this instant, and during the whole time of the closing of the cutting tool 7, the microcontroller makes analog-digital conversion on its input 23 in order to analyze the voltage of the protection means 2. If the digital value converted is zero or less than the threshold voltage, this means that there is no contact between the protective means 2 and the cutting tool 7. The cutting tool 7 continues to close until the signal indicating the complete closure 5 of the tool is emitted by the control unit 17 and received by the input 28 of the microcontroller. If the converted digital value is greater than the threshold voltage, this means that there is contact between the protection means 2 and the cutting tool 7. The output 29 of the microcontroller goes high which saturates the transistor 30 of means 14 and makes it pass. This allows, thanks to the value of the resistor 31, to send an opening signal 10 to the cutting tool through the link 16. The tool is therefore secured by stopping the cutting tool 7 and also by the reopening of the latter to allow the protection means 2 and the elements to be protected possibly jammed. Permanently, the microcontroller 12 also performs a continuity test 15 of the connection between the protection means 2 and the microcontroller 12, by passing the output 19 to the low state periodically, for example every 400 ms. This test corresponds in its function to the continuity test previously described, carried out at

  when the tool is turned on.

  FIGS. 4 to 6 show an embodiment in which the protective means 2 consists of a chainmail glove 60 lined internally with an underglove 61 made of textile material which is a good conductor of electricity. Two connection means with the connection means 10 and 11 are present in this embodiment, in the form of snaps 62 and 63. The first comprises a male part 64 located on the glove 60, the second comprises a male part 65 located on the underglove 61. Each of said male parts 64, 65 is designed to be

  connected to a female part 66 or 67 located on one of the connecting wires 10 or 11.

  In this exemplary embodiment, the male part 65 and the female part 67 of the press button 63 are isolated from the under-glove 61 by an electrical insulator 68 (FIG. 6), the only electrical connection existing between the press button 63 and the glove being an electrical resistance 69. In this way, the electrical circuit comprising the connecting wires 10 and 11, the two snaps 62, 63, the glove 60, and the under-glove 61 has a particular electrical resistance, determined by to resistor 69, which does not have the electrical circuit composed solely of the union of the two female parts 66, 67 of the snaps 62, 63. The microcontroller can therefore differentiate these two electrical circuits and control the stopping of the motor if the glove and underglove are not present. In an alternative embodiment, the

  two snaps are isolated and each equipped with a resistor.

  The presence of the sub-glove 61 improves the electrical contact between the metal rings of the chainmail glove. This underglove also makes it possible to protect the operator's hand against the cold and against any splinters of wood, in particular for an application of the safety device to a pruning shears dedicated to pruning the vine. The protective means 2 can also take the form of a glove without a lining, for example a simple glove made of chain mail, a simple silicone glove loaded with conductive material or the like, while retaining all of the advantages mentioned above. -above. In this case, the two parts of the snaps allowing the connection of the links 10 and 11 are located on the glove in question;

  The protective means 2 taking the form of a glove 60 possibly added to the under-glove 61 is entirely suitable for being used with the protection and safety device as described in FIGS. 1, 2, 3 thanks to the presence of the electrical connections 10 and 11 forming the link between the connection means 62, 63 and the protection and safety device 15 1.

  If necessary, one or more additional press studs can serve as a link between the glove and the under-glove to ensure electrical conduction.

between the two elements.

  Of course, the protection and security device according to the invention 20 can be applied for other types of tools possibly associated with

  other types of protection, while retaining the same functionality.

  Also, this protection and security device can implement

  additional safety functions thanks to the presence of the microcontroller.

  In particular, it will be possible to provide that the microcontroller blocks the tool after a determined duration of use (for example one or two hours, or even more), and requests the user, by any signal, to perform a new initialization; this will prevent excessive use of the tool with the same threshold value, which would be a potential source of accident in the event of fouling

  too important of the protective means in particular.

Claims (15)

- CLAIMS   1.- Protection and safety device (1) intended to be used with a motorized tool (7), said device being associated with a protection means (2) conducting electricity and causing the engine to stop (6 ) of the tool (7) under the action of an electrical voltage known as "contact voltage" resulting from contact or proximity of contact between the tool (7) and said protection means (2 ), which device is characterized in that it comprises at least one means (12) for converting the contact voltage into a digital signal representative of said voltage, for comparing this digital signal with a digital reference signal and for controlling the 'engine 10 (6) of the tool (7) stops as a function of the result of the comparison of the two digital signals.  2.Protection and safety device according to claim 1, characterized   in that the digital reference signal represents a threshold voltage, and in that the protection and safety device (1) sends a stop signal to the motor (6) of the tool (7) if the voltage contact exceeds said threshold voltage.   3. Protection and safety device according to claim 1 or 2, characterized in that the digital reference signal is adjusted automatically, during an initialization step, as a function of the maximum voltage established by contact.   protection means (2) with the tool (7).   4.- Device according to any one of claims 1 to 3, characterized in that   that the comparison between the digital signal representing the contact voltage and the digital reference signal is carried out periodically, according to a frequency adjustable.   5.- Device according to any one of claims 1 to 4, characterized in that the means (12) controlling the stopping of the engine of the tool (7) also controls   its inversion of movement according to the result of the comparison between the signal   digital representing the contact voltage and the digital reference signal.   6.- Device according to any one of claims 1 to 5, characterized in that   that it further comprises a means (9) for controlling the continuity of the connection between the protection means (2) and said control means (9), the latter comprising a connection system (10, 11) with the protective means (2) and causing the engine to stop (6)   if one of these links is broken.   7.- Device according to claim 6, characterized in that the means of   control comprises two wired electrical connections (10, 11) with the protection means (9).   8.- Device according to claim 6, characterized in that the control means comprises a transmitter / receiver connection system with the means of protection (9).   9.- Device according to any one of claims 6 to 8, characterized in that   that said control is carried out at an adjustable frequency.   10.- Device according to any one of claims 1 to 9, characterized in   that the protective means (2) is a glove (60) made of electrically conductive material, associated with an under-glove (61) also made of conductive material. 11.- Device according to claim 10, characterized in that it comprises a means (62) for the connection of a connecting means (10) with the glove (60) and a   means (63) for the connection of a connecting means (11) with the under-glove (61).   12.- Glove according to claim 11, characterized in that the connection means (62, 63) carried by the glove (60) and the under-glove (61) are isolated   electrically conductive materials constituting the two gloves, and are electrically connected to said conductive materials by at least one electrical resistance.   13.- Device according to any one of claims 1 to 9, characterized in   that the protective means (2) is a glove made of electrically conductive material 15 provided with two means for the connection of the connecting means (10 and 11).   14.- Glove according to claim 13, characterized in that the connection means carried by the glove are electrically isolated from the material constituting the glove, and are electrically connected to said conductive material by at least one means of electrical resistance.   15.- Method for securing a motorized tool using the protection and security device according to one of claims 1 to 14, characterized in that it comprises, during each powering up of the device, a step for locking the tool (7) followed by a step for checking the continuity of the connection between the checking means (9) and the protection means (2), by a step for recording the digital signal of reference, the blocking of the tool (7) being lifted if the previous steps have been carried out successfully, and a last step repeated in the measurement loop   of the contact and control voltage of said link.