EP0255433A1 - Portable pneumatic machine with an electronic control system - Google Patents

Abstract

A portable pneumatic machine is provided including an incorporated electronic circuit for controlling and monitoring the operation, which circuit is fed with current delivered by an electric generator rotated by the driving pneumatic air, the electric generator having means for delivering signals representative of at least one operating parameter of the machine usable by the incorporated electronic control and monitoring circuit.

Description

The present invention relates to portable pneumatic machines of the type comprising a body provided with a compressed air supply duct, pneumatic rotary motor means (turbine or vane motor for example) placed in the body, actuated by the flow of compressed air intended to rotate a tool, a device for regulating or cutting off the air flow supplying the machine and an electric generator comprising a rotor and a stator installed in the body. The rotor is capable of being mechanically driven in rotation by the motor means and allows the creation of electrical energy from the pneumatic driving energy of the tool.

The invention finds a particularly important, although not exclusive, application in the particular case of screwdrivers, drills, tappers, and portable pneumatic grinders.

Pneumatic machines of the type defined above are already known. The document FR-A-2 523 891 concerning a rotary penumatic machine with incorporated lighting, shows a machine comprising a rotary member driven in rotation by a mechanism enclosed in a casing and driven by compressed air. The casing, provided for this purpose with means of connection to a source of compressed air, comprises an electric generator with rotor and stator, the rotor of which is driven by the compressed air supplying the mechanism of the machine. This rotor is enclosed in a housing which can be secured to the casing. The generator supplies lighting means carried by the housing and which allow the machine to work in places of difficult access, where the use of a portable lamp is impossible. This machine is, however, of only limited interest.

The present invention aims to provide a portable pneumatic machine which responds better than those previously known to the requirements of practice, in particular in that it allows:
- A command and control of the parameters of the operation of the machine which do not require it to be supplied with energy other than that supplied by the compressed engine air; This avoids the clutter of additional wires which are more likely to cut with the possible security problems that this may pose;
- A command and control of the machine, inexpensive, not significantly increasing the size of the latter, which thus remains very manageable;
- The realization of a large number of functions hitherto little exploited by manufacturers due to the difficulties encountered in their implementation. Integrated mechanical systems, such as torque limiters, pressure and speed regulators, are indeed complex and have limited performance and possibilities. The portable pneumatic machine according to the invention will in particular allow measurement and regulation of the speed of rotation of the tool, tightening by the tool to a predetermined torque and angle and many other functions as described below. , without the need for an external electrical cabinet of bulk and high cost.

To this end, the invention notably proposes a portable pneumatic machine of the type defined above, characterized in that it further comprises:
an electronic circuit for controlling and controlling the operation of the pneumatic machine incorporated into the body of said machine and supplied with current delivered by the electric generator,
- And in that said generator is arranged to also deliver signals representative of at least an operating parameter of the machine usable and used by said circuit.

An advantageous embodiment of the machine comprises an electric generator which supplies a signal representative of the speed of rotation of the motor means. The electronic command and control circuit of the machine has means for selecting a set value for this speed and means for maintaining said speed at this set value. An application of this particularly interesting embodiment can be made to grinders, sanders and other machines whose speed of rotation is a function of the pressure exerted by the operator on the support to be machined.

Another advantageous device presents a pneumatic machine, the electric generator of which delivers a signal representative of the angular position of the rotary motor means and of the tool. The electronic command and control circuit of the machine comprises means for selecting a set value for the angular position and means for stopping the motor means when the tool reaches this value. This arrangement allows the screwing of a screw on a support of variable elasticity. An approximate approach allows the support to be brought into contact with the screw, the latter then being turned by a predetermined angle.

Another pneumatic machine according to the invention is characterized in that the air cut-off device supplying the machine is integrated into the body of said machine and comprises means capable of transmitting a signal representative of the torque exerted by the rotary motor means to the circuit. electronic command and control. The electronic circuit comprises means for selecting a set value at a maximum torque of the output shaft of the machine. When the torque has reached the setpoint, the air is cut off.

Advantageously, the electronic circuit further comprises means suitable for measuring the increase in torque during tightening as a function of time or of the angular position of the driving means, means suitable for comparing (as a function of the foreseeable shape of the anticipated curve from the slope of the increase in torque that we have just measured) the value of the torque at a reference instant t _o with the set value and deduce the remaining tightening time t or the angle α to turn remaining, in order to precisely stop the machine at its set value, and means for activating a timer or a tachometer from this instant t _o suitable for stopping said machine when said tightening time t or said angle α to be turned has elapsed.

Such arrangements make it possible to stop the machine with very high precision. In fact, if the compressed air is cut off only when the set value is reached, there is or may be a slight lag time before the final shutdown. This causes the setpoint to be exceeded.

With means making it possible to determine the characteristics of the torque rise curve as a function of the time or of the angle given by the generator and means making it possible to take it into account to stop the machine, it is possible to cut the air before d '' reach the setpoint and stop precisely on the latter.

In another advantageous embodiment, elastic means are provided connected between the rotary motor means and the spindle on which the tool is fixed. These means make it possible to increase the torque rise time and thus improve the tightening precision. They have a reducing role which is diminishing. They are for example constituted by a spring operating in torsion or in compression, or are constituted by an elastic material, plastic or others. These elastic means are known per se.

In an advantageous embodiment, the means capable of transmitting a signal representative of the torque exerted by the rotary motor means comprise a deformable part capable of immobilizing the motor means in rotation and supporting at least one sensor. The latter may be of the strain gauge type, or of the piezoelectric pressure sensor type or the like.

One can, moreover, have recourse to one of the following provisions:
- Means for storing the electrical energy delivered by the generator, such as a storage battery, of the cadmium nickel type for example, are integrated into the body of the machine;
- At least one display screen for viewing the operating parameters and / or setpoint of said machine is fixed on the body;
- the electronic control and command circuit is programmable.
- means for memorizing the operating parameters of the machine are connected to the electronic control command circuit. They are carried by the machine body and can be detached from the body, which allows the results to be used without immobilizing the machine.

• - La figure 1 est une vue en perspective partiellement en coupe, d'une machine selon l'invention, servant au vissage et permettant un contrôle du couple de serrage et de la position angulaire de l'outil ;
• - La figure 1a est une vue schématique, par­tielle et en coupe de la tête d'une machine de vissage de la figure 1.
• - La figure 2 est une vue en perspective, partiellement en coupe, d'une variante préférée de l'invention permettant par exemple le meulage avec régulation de la vitesse ;
• - La figure 3 est un bloc diagramme du circuit de contrôle et de commande de la machine pneumatique portative selon l'invention.

The invention will be better understood on reading the following description of a particular embodiment given by way of non-limiting example. The description, as well as that of a preferred variant, refers to the accompanying drawings in which:

• - Figure 1 is a perspective view partially in section, of a machine according to the invention, used for screwing and allowing control of the tightening torque and the angular position of the tool;
• - Figure 1a is a schematic, partial and sectional view of the head of a screwing machine of Figure 1.
• - Figure 2 is a perspective view, partially in section, of a preferred variant of the invention allowing for example grinding with speed regulation;
• - Figure 3 is a block diagram of the control and command circuit of the portable pneumatic machine according to the invention.

FIG. 1 shows a hand-held screwdriver with incorporated controls of the output torque of the machine and of the tightening angle of the tool adaptable to the spindle of the screwdriver produced according to the invention. It comprises a body 1 which may be made of hard plastic or metal or any other suitable material. A compressed air supply duct 2 makes it possible to supply the machine and to drive a vane motor 3 in rotation. This vane motor 3 drives via a reduction gear 4 and a return of angle 5, the tool (not shown). The reducer is, for example, of the epicyclic type.

The geared motor assembly 3, 4 is mounted to rotate freely in the body 1 held manually by an operator. An electric generator 6 comprising a rotor 7 and a stator 8 is made integral with the axis 9 of the vane motor 3 suitable for mechanically rotating the rotor 7. An air cut-off device 10 comprises a closing valve 11, an electromagnet 12 capable of being actuated by an electronic circuit 13 for controlling and controlling the operation of the pneumatic machine. The circuit 13 is incorporated into the body 1 and supplied with current delivered by the generator electric 6. The latter is arranged to deliver signals representative of at least one operating parameter usable by the circuit 13. A manual control 12a (represented in the form of a push button in FIG. 1) makes it possible to open a valve supply of compressed air 61, placed before the valve 11, on the air inlet 2. This control can also, for example, be in the form of a lever 42 (see FIG. 2).

Alternatively, the valve 11 is closed in the rest position and the manual control 12a will ensure its opening without additional supply valve 61.

FIG. 3 shows a block diagram for command and control of an electronic circuit 13 according to the invention, supplied by the incorporated electric generator. The elements of the basic electronic circuit, used by a pneumatic machine according to the invention, have been shown by blocks in solid lines, in solid double lines the elements external to the circuit, and in dotted lines the additional control and command elements of the electronic circuit. suitable for a specific use. The blocks are connected together by solid or dotted lines schematically showing the main electrical connections. This schematic graphic representation in no way presumes the number of conductors necessary to convey the power or the electrical information necessary for the operation of the device. In addition, other liaisoins are quite possible, allowing for example to bypass certain elements such as the storage battery. These variants are easy to design and will not be developed further.

The elements appearing in this block diagram are produced using electronic components known per se, discrete or in the form of circuits. integrated. They therefore do not require any particular explanation.

The electric generator 20 supplies a voltage rectifier 23 and also directly delivers signals representative of the operating parameters of the machine via a voltage digitizer 21 and a pulse counter 22. The voltage rectifier 23 is connected to a battery 24 of accumulators integrated into the body 1 of the machine, placed for example near the duct 2 for supplying compressed air to the machine (see fig. 1). The battery 24 makes it possible, by means of stabilized supply means 25, to supply electricity to force sensors 26. These can be strain gauges, or even pressure sensors of the piezo type. electric or other. These sensors are fixed on a deformable support part 15, suitable for immobilizing the vane motor 3 and its associated reduction gear 4 in rotation. They are connected to the electronic circuit for controlling and controlling the operation of the machine and are capable of supplying a signal representative of the torque exerted by the turbine 3 on the deformable part via a voltage amplifier 27.

This voltage amplifier 27 supplies means 28 for displaying the torque. By means of a computer 29 or a threshold detector 30, the amplifier 27 attacks the electromagnet 13 making it possible to open or close the valve 11. The threshold detector 30, connected to means 31 providing an adjustable set value (potentiometer, keyboard, or any means allowing the input of external data) and which can be connected to display means 32 of the set value, allows, by comparing with the information coming from the voltage amplifier 27, to give an instruction solenoid 12.

Thus, when the force sensor indicates a value equal to the setpoint of the slave system, a control instruction is given. In the case of a machine for which it is desired to limit the torque applied to the working spindle 16 to a maximum value, this involves closing the compressed air supply.

However, other cases are possible, in particular when it is desired to stop the tool in a determined angular position from a tightening torque. In which case the control instruction then attacks a timing circuit (not shown). In an advantageous variant of the machine according to the invention, means 60 for memorizing the operating parameters are connected to the electronic circuit, for example to the digitizer 21, to the voltage amplifier 27 and / or to the computer 29. These means, carried by the machine body can be included in a housing which can be detached from the body.

Figure 2 shows an electronic speed regulation grinder according to the invention. It comprises a body 40, a compressed air supply connection 41 which can for example be of the quick coupling type and a manual control 42 shown in the figure in the form of a lever, but which can be a button, or any other known means. A solenoid valve 43, provided with a needle screw 44 controlled by a micro-motor 51 supplied by the electric generator, makes it possible to control the flow of compressed air supply to the vane motor 45 which causes the rotation of the spindle 46 on which comes to fix the tool (not shown).

The operation of this solenoid valve 43 is controlled by means of the electronic circuit 47 of the type comprising at least part of the elements of FIG. 3. The information on the rotation of the spindle 46 is given to the electronics from the output of the electric generator 20. The voltage digitizer 21 makes it possible to supply a signal representative of the speed of rotation of the spindle during operation to means for displaying the speed 33. A clock 34, powered or not by the generator, and the pulse counter 22 connected to the output of the generator 20 are connected to means 35 for maintaining a speed regulation setpoint selected by means 35a and are capable of acting on the valve 43 to modulate the air supply. The speed of the machine can then be modified in a determined direction, after comparison of the speed measured with a reference speed given in reference to the electronics by the selection means 35a.

The pulse counter 22 also makes it possible to deliver signals representative of the angles of rotation of the output pin. Via the computer 29 it attacks the electromagnet 13. This computer 29 is connected to means for selecting a set value 29a of the desired angle of rotation and can be connected to display means 29b from this angle. Thus, the machine is stopped when the measured angle of rotation becomes equal to a value given by the reference means 29a.

During the tests of realizing a machine according to the invention, an accuracy of the order of a degree could be obtained. The tool indeed turns very slowly when a determined angular rotation of the spindle is carried out; the torque exerted being also sufficient, the cut off of the compressed air causes an almost immediate stop.

In order to obtain an even more precise stopping of the tool, in a position corresponding exactly to the set target value, the electronic circuit 13 may include measuring means 70, 71 suitable for measuring the increase in the value of the torque. while the tightening either as a function of time, then for example provided by the clock 34 (connection not shown in FIG. 3), or as a function of the angular position of the rotary motor means given by the pulse counter 22 (connection not shown in Figure 3). The circuit 13 also includes calculating means 72 connected to the means for selecting a set value 31 and to the measuring means 70, 71, said means being suitable for calculating as a function of the past shape of the increase curve of the couples the foreseeable form of this increase and deduce therefrom from a reference time t _o or from a reference angle α _o the tightening time t or the tightening angle α to turn remaining necessary to reach the setpoint (torque or tightening angle). Such means for measuring and calculating are known per se and those skilled in the art will choose from the integrated or discrete circuits on the market the elements necessary to produce them.

Means 74 for cutting off the supply of compressed air after the time t or the rotation of an angle α , connected to the calculation means 73, ultimately ensure a precise stop at the set value by acting on the electromagnet 12.

In order to further improve the precision as to stopping at the correct set value, elastic means 5a can be added, for example inside the body of the machine near the bevel gear 5 as shown diagrammatically in FIG. 1. Such elastic means allow a differential rotation between the part 9a of the shaft 9 rigidly connected to the rotary motor means and the part 9b rigidly connected to the tool via the pin 16. These elastic means allow a reduction with damping which results in increasing the torque build-up time and therefore improving the tightening pressure.

These elastic means are constituted so known per se and will not be developed further.

Other elements can advantageously be added to this control and command circuit of a pneumatic machine according to the invention. For example, a system 50 allowing the programming of the tightening duration in the case where the machine is a screwdriver. It is also possible, by means of a speed change device 52, to modify the operating parameters of the machine for example to have a different working speed.

The operation of the machines produced according to the invention is explained below.

Compressed air is connected to the machine by adapting a connection to the compressed air supply pipe 2. The tool is then stopped. By action on the control means 12, 42, (the closing valve 11 being open or the needle screw 44 being preset in a determined position), the compressed air supplies the rotary motor means 3, 45 driving the reducer 4 which makes turn the spindle 16, 46 on which the tool is fitted. Simultaneously, the rotary means 3 drive the current generator 6, which after having been transformed, is stored, for example, in the battery 24 which is used for the general supply of the control-command circuit.

In the case of a screwdriver and beforehand, the operator will have displayed in setpoint, by means 31 (keyboard, potentiometer, ...) the setpoint of the maximum torque at which he wants to arrive during tightening. The screwing of the screw is then carried out and the torque increase during tightening is done. When the force sensors transmit a representative signal giving a torque of value equal to the set value, the excitation of the electromagnet 13 causes the valve 11 to close and the machine.

In the case of the operation of a grinder-type machine, the operator displays the speed at which he wants to carry out his grinding operation by means 35a of selecting a set value. During grinding, the surface condition of the workpiece, the manual pressure exerted by the operator, and the condition of the tool will vary. The speed of rotation, which is a function of these parameters, will therefore also vary and will then make it possible to regulate the air intake by acting through the regulating means 35 on the needle valve 44 as previously described, by action on the micro- motor 51.

As goes without saying, and as it follows from the above, the invention is in no way limited to those of these modes of application and embodiments which have been more especially envisaged; it includes, for example, means which will allow, in particular in the case of screwdrivers:
- the screwing of self-drilling or self-tapping screws, in parts requiring a torque greater than the tightening torque,
- tightening approach at high speed and locking the screw or nut at low speed, but at higher torque,
- a paint marking of tight screws or nuts,
- programmable tightening times,
- automatic gear changes.

For grinders, tappers, and drills:
- in addition to regulating the rotation speeds, programming speeds, in particular to have a gradual start.

Thanks to the machines according to the invention, better quality in the work performed by the operator and better control of this work is possible. The display of operating parameters on the machine allows the operator to adapt to the particular conditions of his work at all times.

It is also possible to provide outputs on the machine to which separate equipment will come to connect. A dialogue between the incorporated electronic control and command circuit of the machine and of the systems 55 for external data processing (recording of the working parameters for example) is then possible. Modifications concerning the settings of the machine itself, or even the enslavement to the machine of a fixed station on which the portable machine according to the invention would be mounted or more generally, its use by a robot are therefore entirely possible.

By way of example, one can cite the automatic reversing of a drill for breaking the chips when the working torque reaches a predetermined maximum value.

Claims (10)

1. Portable pneumatic machine comprising: a body (1) provided with a compressed air inlet duct (2), rotary motor means (3) placed in the body, actuated by the flow of compressed air and intended driving in rotation a tool, a device for cutting off (10) the air flow supplying the machine, an electric generator (6) comprising a rotor (7) and a stator (8) installed in the body, the rotor (7 ) being able to be mechanically driven in rotation by the rotary motor means (3), characterized in that the pneumatic machine further comprises:
an electronic command and control circuit (13) for the operation of the pneumatic machine incorporated into the body (1) of said machine and supplied with current delivered by the electric generator (6),
- And in that the generator (6) is arranged to also deliver signals representative of at least one operating parameter of the machine usable by said circuit. 2. Pneumatic machine according to claim 1 characterized in that the air cut-off device (10) supplying the machine is integrated into the body (1) of the machine and in that it comprises suitable means (25,26) transmitting a signal representative of the torque exerted by the rotary motor means (3) on the tool to the electronic command and control circuit (13) for the operation of said machine, and in that said circuit (13) comprises means for selection (31) of a set value at a maximum torque output from said motor (3) and control (29) means of the air cut-off device (10) when the torque has reached said set value. 3. Pneumatic machine according to claim 1 or 2, characterized in that the electric generator (6) is arranged to deliver a signal representative of the angular position of the rotary motor means (3) and of the tool, and in that the electronic circuit (13) for command and control of the machine comprises selection means (29a) of a set value of the angular position of the tool and of control (29) of the air cut-off device (10) when the angular position of the tool reaches said set value. 4. Pneumatic machine according to any one of the preceding claims, characterized in that it further comprises means (70, 71) of measurement suitable for measuring the increase in the value of the output torque of the motor means during tightening , as a function of time or of the angular position of the motor means, calculation means (72, 73) capable of deducing from the increase in said torque, the subsequent foreseeable form of the increase in torque and deducing therefrom, from a reference time t _o or a reference angle α _o , the tightening time t or the angle α remaining necessary to reach the set value of the torque and the means (74) for activating a time delay or a tachometer from this instant t _o or this angle α _o suitable for stopping said machine at the end of time t or the rotation of the angle α. 5. Pneumatic machine according to any one of the preceding claims, characterized in that it most comprises elastic means for multiplying and damping the torque exerted by the rotary motor means on the tool making it possible to increase the torque rise time and improve the tightening precision. 6. Pneumatic machine according to claim 1, characterized in that the electric generator (6) is arranged to provide a signal representative of the speed of rotation of the rotary motor means (3) and in that the electronic control and control (13) of the machine comprises means for selecting (35a) a speed reference value and means (35) for maintaining said speed at said reference value. 7. Pneumatic machine according to any one of the preceding claims, characterized in that it comprises integrated means (24) for storing the electrical energy delivered by the generator, such as a storage battery. 8. Pneumatic machine according to any one of the preceding claims, characterized in that it comprises at least one display screen (28, 33, 29b, 32) associated with the electronic command and control circuit making it possible to display at least one of the operating parameters of the machine or one of the set point values to be observed in the use of the machine, said screen being fixed to the body (1) of the machine. 9. Pneumatic machine according to any one of the preceding claims, characterized in that the electronic control and command circuit is programmable. 10. Pneumatic machine according to any one of the preceding claims, characterized in that it comprises means (60) for memorizing the operating parameters of the machine, the means being carried by the body (1) of the machine.

Images