EP0119928A1 - Dynamometric tightening apparatus - Google Patents

Abstract

This device makes it possible to display the torque reached by the tightening tool (1) on a housing (7) which is independent of the tool itself. To this end, the latter comprises diodes (3a, 3b) for emitting infrared radiation, for example, while the housing (7) comprises diodes (8a, 8b) receiving the same radiation. In this way, the tool can be used in all positions while the housing (7) placed in a clearly visible location displays the value of the torque applied to the part to be clamped.

Description

The present invention relates to tightening tools such as keys, screwdrivers or the like by means of which one can tighten parts with a predetermined torque. These tools called dynamometric have been known for a long time and we have tried to improve them in the direction of a more practical use by providing in the tool electronic display means, for example by light-emitting diodes, making it possible to make the value directly readable. of the torque actually applied to the part to be clamped.

These tools, although more practical than fully mechanical wrenches, have retained certain disadvantages.

First of all, the electronic circuit requires a power supply which, due to the limited space available in the tool, cannot be bulky. In this way, the autonomy of the tool in terms of the supply of electrical energy is low. Secondly, the display being produced behind a window on the handle of the tool, it is often hidden from view during use in places that are not easily accessible. This is particularly troublesome in the case of screwdrivers which are rotated during tightening.

Thus, the case where, during use, the display is easily visible to the user only rarely arises.

The invention aims to remedy these drawbacks.

It therefore relates to a dynamometric tightening device comprising a tightening tool such as a wrench, screwdriver or other, the tightening torque being captured and displayed to allow the control of the torque exerted on the part to be tightened, characterized in that said tool comprises means emitting radiation carrying information relating to said couple and in that said tool is associated with means receiving said radiation provided with means for remote display of said couple.

A device thus arranged makes it possible to provide a display device in an autonomous box placed near the workplace and receiving the radiation carrying information concerning the torque which is applied using the tool.

The housing can be placed in an easily visible location and the display have a large dimension because it is not able to impose dimensional constraints for the production of the housing. This can include battery power or even mains power. As for the tool, the transmission means can be of small dimensions, entirely compatible with the space available in the handle of the tool.

The invention will be better understood on reading the description which follows of an embodiment of the apparatus according to the invention.

• - la Fig. 1 est une vue schématique de l'appareil suivant l'invention, l'outil étant une clé de serrage ;
• - la Fig. 1A montre schématiquement l'agencement des sources de rayonnement disposés dans l'émetteur ;
• - la Fig. 2 montre une vue en perspective d'un outil utilisable selon l'invention et constitué par un tournevis ;
• - la _Fig. 3 est un schéma simplifié de l'émetteur logé dans l'outil ;
• - la Fig. 4 est un schéma simplifié du récepteur logé dans le boîtier ;
• - la Fig. 5 est un organigramme de certaines fonctions réalisées dans l'émetteur
• - la Fig. 6 montre un chronogramme des émissions des outils de plusieurs appareils suivant l'invention, utilisés dans un même local ;

In the accompanying drawings, given by way of example:

• - Fig. 1 is a schematic view of the device according to the invention, the tool being a tightening wrench;
• - Fig. 1A schematically shows the arrangement of the radiation sources arranged in the transmitter;
• - Fig. 2 shows a perspective view of a tool usable according to the invention and consisting of a screwdriver;
• - _F ig. 3 is a simplified diagram of the transmitter housed in the tool;
• - Fig. 4 is a simplified diagram of the receiver housed in the housing;
• - Fig. 5 is a flowchart of certain functions performed in the transmitter
• - Fig. 6 shows a chronogram of the emissions from the tools of several devices according to the invention, used in the same room;

In Figure 1, there is shown a dynamometric tightening device according to the invention.

This device comprises a tool 1. the mechanical part of which can be designed according to the prior art, its characteristics therefore not forming part of the invention. The handle of this tool is of square or rectangular section, each side face of which receives, at least in the example described, emitting diodes .3a and 3b. The handle is also provided with a keyboard 4 comprising selection keys, an on-off key 5 and a test key 6.

Fig. 1A shows that the two diodes.3a and 3b which are respectively mounted in the four faces of the handle 2 are arranged at 90 ° from one another and they emit in a 90 ° opening cone. The radiation pattern is therefore omnidirectional. Of course, other emission devices are possible such as for example a round tube or the like.

Preferably, the radiation used is located in the infrared range, at a wavelength which can be chosen between 200 and 1200 nm, for example.

An electronic circuit and a power source are housed in the handle 2 but these elements have not been shown in FIG. 1.

The tool 1 is associated with a box 7 for receiving radiation and for displaying. This box contains diodes receiving the radiation emitted by the emitting diodes 3a and 3b., These receiving diodes 8a and 8b being placed behind windows 9 arranged in the upper surface of the device. It is also possible to use a single diode receiving the radiation in a cone of about 120 °.

In the example described and shown, the radiation has a wavelength situated in the infrared range.

The housing 7 also includes a display window 9 provided with any display device known in the art. Light-emitting diodes or liquid crystals may be suitable for example. On this housing are also provided a light-emitting diode 10 which lights up under certain operating conditions of the device, a loudspeaker 11 which produces a sound also under certain operating conditions, a volume control button 12 for the loudspeaker 11, a setpoint selector 13 with four positions for example, a clearance 14. setpoint locking buttons, an on-off button 15, a test button 16, a programming button 17 and a selector 18 for changing the units displayed by the device. The housing 7 can be moreover, provided with a mains supply associated or not with a battery or the like allowing its autonomous operation.

Fig. 2 shows another tool consisting of a screwdriver. The latter is provided with the same elements as the key of FIG. 1 except that the emitting diodes are arranged in a resistor zone 19 allowing lateral radiation over 360 ° of the screwdriver.

Fig. 3 represents a simplified diagram of the circuit of the transmitter placed in the tool 1. The latter comprises sensors 20 of the applied torque, the output signal of these sensors being transmitted to a differential amplifier 21. The latter is connected by its output to a processing circuit 22 which preferably comprises a microprocessor. The functions performed by the processing circuit 22 are as follows. - First of all, it ensures the conversion of the analog values supplied by the differential amplifier 21 into digital values capable of being processed by the microprocessor. The latter ensures the coding of the digital values thus obtained in a series of pulses modulated in position. We will see later that the message prepared in the transmitter is composed of wave train packets, each packet comprising an identification part of the tool in question as well as a digital part representing in particular the value of the applied torque by the tool to a part to be tightened. During the tightening preparation phase, the part of the package containing a numerical value representing a torque can be a set value which the user can choose using his keyboard 4 and which is then sent, then received and stored in the housing 7.

The pulse trains prepared in the processing circuit 22 are applied to a power stage 23 controlling, at the rate of the pulses received, the emitting diodes 3a and 3b by an all or nothing signal.

Of course, the processing circuit is connected to the keyboard 4, to the test button 6 and to a supply circuit 24 by means of the on-off button 5. The microprocessor is associated with a sequencer circuit 25. which ensures that the transmitter only provides an output signal when it is strictly necessary. The operating mode ensured by this sequencer will be explained later in connection with FIG. 5.

Preferably, the processing circuit 22 includes means making it possible to sweep the pulses. Indeed, if several devices according to the invention are used in the same room, it is important that the signals coming from different transmitters cannot interfere and the fact of sweeping the signal makes it possible to limit the interference between several transmissions.

Fig. 4 shows a simplified diagram of the circuit housed in the housing 7. This housing firstly comprises a circuit 26 intended to shape the signals which are applied to it by means of the diodes 8a and 8b. The formatted signals are transmitted to a processing and decoding unit 27 which is preferably produced in the form of a microprocessor. This microprocessor is connected to the various members controlled by the buttons which have been listed above during the description of the housing 7.

Between the processing unit 27 and the display circuit 9. is provided an interface 28 of conventional type intended to convert the output signals of this unit into signals suitable for being displayed by the display elements such as those comprising light-emitting diodes, for example. The box 7 also includes a supply circuit 29 as well as a sequencer 30.

It is also possible to provide in the processing unit 27 a specific output 31 intended for the transmission of the information collected by the unit to a recording device 32 outside the device. This recording device can optionally receive information from several devices according to the invention, placed in the same room or workshop for example.

The operation of the apparatus according to the invention is as follows. When a user wishes to apply a given torque to a part to be tightened, he selects this torque using the keyboard 4 whereby the emitter circuit of FIG. 3 emits a train of pulses representing on the one hand the identification of the tool and on the other hand the value of this couple. This torque, which is then considered as the setpoint, is received in the housing 7 and stored in the processing unit 27. It is also stored in the processing and control circuit 22 of the transmitter. Of course, the set value can be displayed by the display device 9 on the housing 7.

Part of the program implemented in the processing circuit 22 is illustrated by the flow diagram of FIG. 5A this program being executed when the user proceeds to tighten the part up to the setpoint torque which has just been stored both in the tool 1 and in the housing 7.

During tightening, the program performs several tests to find out whether the applied torque corresponds to 10%, 50%, 80%, and finally 100% of the programmed setpoint torque.

The microprocessor of the processing circuit 22 is capable of controlling the sequencer 25 in such a way that it locks the operation of the sensors 20 for predetermined periods of time, the length of these periods being all the shorter as the value of the tightening torque approaches the setpoint torque value. Thus, at each of the percentages which have just been mentioned, the sequencer .25 orders measurements which are spaced in time, respectively 500. ms, 100 ms, 50 ms and 20 ms, for example.

To this end, the processing circuit comprises four timing members which can, for example, be embodied in registers of the microprocessor of this circuit. these registers being decremented at the rate of a basic clock which is part of this Der- _n i _e r.Avant to be decremented, each of the registers contains a value that, given the clock frequency , establishes one of the time periods mentioned above.

The flow diagram of FIG. 5 also reveals another feature of the invention which makes it possible to avoid that, when the user releases his effort during a tightening procedure, the process immediately falls back to too low an analysis speed, which could be dangerous for the work in progress if the user makes a sudden movement. In other words, when any of the percentages mentioned above is crossed for the first time, a period of time of a predetermined length (of 5 seconds for example) is triggered and the program then ensures that, during this period, the succession of measurements is spaced in time by an interval which corresponds to that established before these 5 seconds begin.

In the microprocessor of the processing circuit 22, other timing registers 37, 38 and 39 are therefore provided capable of establishing a predetermined period of time (5 seconds for example) as a function of the frequency of the clock. basic.

The program thus proceeds as follows according to the flow diagram of FIG. 5. At the start of a tightening process, the applied torque is, of course, less than 10% of the set torque and, while the tightening torque remains below this value, a test is performed at 40 to find out whether the tightening torque becomes equal to 10% of the setpoint torque. If the test is negative, the program performs a test at 41 TF = 0? to find out if timer 37 has reached zero. If this test is positive, the program starts the timing device 33 and the sequencer 25 is controlled in such a way that the torque measurements are spaced by the duration fixed by the timing device in question, that is to say say, 500 milliseconds in the example.

As soon as the value of the tightening torque exceeds 10% of the set torque, the test at 40 receives a positive response and the program then goes to a test 42 C>, C to find out if the tightening torque is greater than or equal to the torque setpoint. If the test is negative, the program performs another test at 43 to see if the tightening torque is greater than or equal to 80% of the setpoint torque and if this test is also negative, another test at 44 is carried out to see if the tightening torque is equal to or greater than 50% of the setpoint torque. If the response to this test is also negative, the timer 37 is started for a duration here fixed at 5 seconds. At the end of the period of time fixed by the timing device 37, two successive tests at 45 and 46 are carried out to find out whether the timing devices TD, TE have arrived at the value 0. If the first test proves positive , the second is performed and if the second receives a positive response in turn, the sequencer 25 is controlled via the timing circuit 34 to establish a spacing between the measurements of 100 milliseconds. If this last test in 46 receives a negative response, the same sequencer is controlled to space out the measurements by 50 milliseconds thanks to the timing device 35. If, on the other hand, the test at 45 receives a negative response, the timing device 36 is started to space the measurements by 20 milliseconds only. This means that the tightening torque exceeds 80% of the setpoint torque. If the test at 43 receives a positive response, the three timing members 37, 38, 39 are started for 5 seconds to maintain in any case a time interval between the measurements of 20 milliseconds.

When the answer to the test carried out at 42 is "yes", the applied torque is equal to the setpoint torque and a signal is delivered which, via the transmission and reception diodes and the circuits of the housing 7, trigger the loudspeaker 11 and / or the signaling diode 10.

During this whole process, the emitting diodes 3a and 3b of the tool transmit data packets at the intervals fixed as a function of the torque applied, by the timing members 33 to 36, to the receiving diodes 8a and 8b, each packet being formed by an identification part and a numerical part representing the value of the applied torque. This is permanently visible on display 9.

On _F ig. 6, there is shown a timing diagram of the signals emitted by two tools belonging to apparatuses according to the invention placed in the same room or close to each other so that their transmitted signals can be received by the boxes 7 of the two devices.

During a transmission, each tool emits packets of pulses P _a , P _b , P _c etc ... and P _a-1 , P _b-1 , P _c-1 , etc ... each composed of an identification part ID and a digital part NM representing the value of a setpoint torque to be transmitted or of an applied torque, measured at the instant considered.

The intervals between the pulse packets T _a , T _b , T _c , etc ... and T _a-1 , T _b-1 , T _c-1 , etc ... are not constant but randomly variable over a period involving the emission of sixteen successive packets of pulses. Thus, the interval T _a can last 5 ms, the interval T _b , 7 ms, the interval T _{c B} ms, etc., the same intervals being again successively established after transmission of 16 pulse packets. As the distribution of the intervals is random for each tool, the probability of a simultaneous emission of pulse packets by two nearby tools is low, and in the event that such transmission nevertheless takes place, the processing units 37 of the boxes 7, will interpret the signals received as being false. The coincidence of two packets of pulses from two tools cannot therefore hinder a faithful transmission of information since the following packets of pulses will have an extremely low probability of coincidence.

The pulses of each pulse pack are modulated in position to transmit the tool number and the torque value considered; their duration can be 100 µs, for example.

Claims (15)

1. Torque tightening device comprising a tightening tool (1) such as a wrench, a screwdriver or the like, the tightening torque being captured and displayed to allow the control of the torque exerted on the part to be tightened, characterized in that said tool (1) comprises means (3a, 3b, 22) emitting radiation carrying information relating to said torque and in that said tool (1) is associated with receiving means (7, 8a, 8b, 27 ) of said radiation independent of the tool and provided with display means (9) remote from the evolution of the torque as and when tightening. 2. Apparatus according to claim 1, characterized in that said emitting means comprise diodes (3a and 3b) emitting said radiation, said receiving means comprise at least one diode (8a, 8b) receiving said radiation, and in that these diodes work in the infrared range, preferably at a wavelength chosen from the range of 200 to 1200 nm. 3. Apparatus according to claim 2, characterized in that, in the case where the tool is a handle wrench (2) of square or rectangular section, said emitting diodes (3a, 3b) are arranged in the lateral faces of said handle (2). 4. Apparatus according to claim 3, characterized in that each face of the handle (2) of the tool (1) comprises two diodes arranged so as to emit in a cone whose angle at the top is 90 °. 5. Apparatus according to claim 2, characterized in that in the case where the tool is a screwdriver (1 A) with approximately cylindrical handle, said emitting diodes are arranged in the handle thereof so as to emit in a plane at an angle of 360 °. 6. Apparatus according to any one of claims 2 to 5 characterized in that said tool (1, 1A) comprises sensors (20) for the acquisition of the torque applied to the part to be clamped, a differential amplifier (21) connected to said sensors as well as a control and processing circuit (22) connected to said amplifier (21) and intended to ensure the conversion of the analog signals supplied by the latter into digital signals and, to put signals in a form proper to the 'emission, under the control of a sequencer circuit (25) and in that the output of the control and processing circuit (22) is connected to said emitting diodes via a power stage (23). 7. Apparatus according to claim 6, characterized in that a keyboard (4) mounted in the tool is connected to said processing control circuit (22) to allow the setting of a setpoint torque to be reached when tightening d 'a piece. 8. Apparatus according to any one of claims 2 to 7, characterized in that said transmitting means comprise a receiving circuit (26) for shaping the signals received by the receiving diode (s) (8a, 8b), a processing unit (27) connected to the receiver circuit and intended to interpret the signals thus formatted for display, signaling means (10, 11) for providing a perceptible signal when the torque applied by said tool (1, 1A) reaches a previously selected setpoint, display means (9, 28) and a sequencer circuit (30) for coordinating the operations executed in said processing unit. 9. Apparatus according to claim 8 when it depends on claim 7, characterized in that said processing unit (27) comprises means (14) for recording several target couples chosen by means of said tool and means ( 13) for successively selecting the setpoint torques thus memorized for tightening a part to be tightened with the value of the selected setpoint torque. 10. Apparatus according to any one of claims 6 to 9, characterized in that said control and processing circuit (22) and said sequencer (25) are produced by a microprocessor. 11. Method for the implementation of the device according to claim 10, characterized in that it consists in generating and transmitting in said tool (1, 1A) pulse packets each comprising a part representing the code of the tool considered and a part representing the torque applied to the part to be clamped, and in that it consists in transmitting the successive pulse packets at randomly determined intervals over a predetermined and repetitive period of time. 12. The method of claim 11, 'characterized in that it consists in transmitting said pulse packets at a swept pulse frequency, the successive pulses being modulated in position for the transmission of the useful signal. 13. Method according to any one of claims 11 and 12, characterized in that it consists in memorizing before the tightening of the part a setpoint torque (C) to compare this setpoint torque with the value of the torque (C) actually applied to the part to be clamped, and to carry out successive measurements of this applied torque at successive intervals whose lengths decrease as the value of the applied torque (C) approaches the reference torque (Cp). 14. Method according to claim 13, characterized in that the reduction of the intervals separating successive measurements of the applied torque (C) is carried out each time a predetermined percentage of the setpoint torque (C) is reached. 15. The method of claim 14, characterized in that it also consists in delaying the reduction of the interval between two measurements for a predetermined period of time after the current percentage of the setpoint torque is reached.

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