EP3028813B1 - Hand tool, in particular an impact wrench - Google Patents

Description

The present invention relates to a hand tool, in particular in the form of a pneumatically driven impact wrench with the features of independent claim 1.

Generic impact wrench with rotating intervention tools are known in different embodiments with mechanical, electric or pneumatic drives. Such impact wrenches generally serve to tighten or loosen screw connections, i. of screws and / or nuts, v.a. if high torques are required for the appropriate tightening and / or loosening operations.

Under an impact wrench is understood in the present context, a tool that combines a fast or slowly rotating tool shaft with an end fitting tool such as. A so-called hex socket or the like. With a percussion, which directed in the direction of rotation of the tool shaft and wielding a rotary motion superimposed beating float. In this way, such impact wrench superimposes a rotating release or tightening movement of a with the fitting tool such as. the socket connected hexagonal screw head or a hexagon nut a striking rotary motion or beating pulses acting in tightening or loosening the screw head or on the threaded nut and thus makes it possible, a very tight-fitting screw with the application of a smaller Torque solve as this would be possible without simultaneous impact movement. The same applies to a tightening of such a screw in which by the simultaneous use of the percussion also a higher tightening torque can be achieved than in conventional screwdrivers without accompanying percussion.

Electrically operating devices have a tool shaft driven by an electric motor and a percussion device designed according to the intended use. The advantage of electric impact wrenches is in the permanent provision of small and medium torques at relatively compact device sizes and thus a certain amount of location independence, as to their operation usually only a connection to the local power grid or, if this is not directly possible to a generator provided for such a purpose must be produced. Due to the developments in the sector of energy storage technologies are also Devices that are equipped with accumulators to find more and more frequently, with their application is usually limited to the home user sector or semi-professional applications.

For higher requirements with regard to the duration of use and / or the torques to be overcome, as well as in professional use, normally air-operated or pneumatically operated impact wrenches are used. Such pneumatically operated impact wrench usually have a vane motor, which is rotated by compressed air in rotation and drives in this way the rotatably connected with the vane motor tool shaft. An internal percussion mechanism can, for example, have an energy store and suitable devices for introducing the impact pulses acting in the direction of rotation into the rotating tool shaft. As mentioned above, a variety of tool attachments can be arranged at the front end of the tool shaft, for example. Screw heads with hexagonal or polygonal, so-called. Screw nuts with which particular screw can be tightened or loosened, the tightening torque is usually very precisely adjustable. When loosening and tightening such screw is usually the impact function, are generated in the rapid impact sequences in the radial direction of the tool shaft, indispensable.

From the DE 10 2011 051 121 A1 An impact wrench is already known, which has an improved switch. The switch is provided on an outer housing of the impact wrench. A provided on the outer housing handle comprises an air inlet and an air outlet channel. The outer housing is provided with a receiving recess having a forward and reverse rotating air intake passage connected to the engine. As soon as air enters one of the air intake ducts, the engine rotates. About a switch having an actuating rod which is connected on the one hand with the air inlet channel and on the other hand with a trigger, the air inlet channel can be opened or closed. The switch comprises a switching valve which is connected to a push rod. As soon as a user presses the push rod, the changeover valve is rotated, so that a passage opening can be aligned with the forward rotation and reverse rotation air inlet passage, respectively.

The US 2011/0088921 A1 describes a control device for a rotational speed control of a pneumatic tool. In this case, an air supply unit is connected to an air inlet line and supplies a controllable Valve with air. Via the controllable valve, the air flow can reach the compressed air motor of the compressed air tool via lines. The control process is operated via an on / off switch. The revolutions of the drive shaft can be detected by a revolution speed sensor. A speed signal is transmitted to a microcontroller, which compares the current rotational speed with the target speed. By means of a control signal, the rotational speed can be adjusted via the regular valve.

In the DE 23 14 769 A a torque limiting device for a rotary impact driver is disclosed. The rotary impact wrench comprises for this purpose a compressed air-driven engine, which is connected via a supply line to a compressed air source. In the supply line there are serving as a switch 3/2-way valve, an adjustable throttle valve, serving as a hand switch 3/2-way valve and to change the direction of rotation a 4/2-way valve. Of the located within the impact wrench air ducts are diverted control lines between the 3/2-way valve and the air motor, which are connected to a common control line. The control line leads to a serving as an amplifier 3/2-way valve, which is connected to a time valve, which in turn is connected via a throttle check valve to the serving as a switch 3/2-way valve. When operating the 3/2-way valve, compressed air can flow from the pressure source through the supply line, the 3/2-way valve and the air duct to the engine. At the same time control air is supplied to the 3/2-way valve via the control lines, which can thus be brought into switching position. This will actuate the timer valve, interrupting the air supply to the engine.

In the interests of ease of use and a reduction in the burden on the user, these impact wrenches should be as compact and lightweight as possible with high performance, to which the pneumatic drive delivers its magnitude due to the high power density possible. However, in conventional impact wrenches with their manual switches and valves, there are some restrictions which undesirably reduce power density, or require a corresponding increase in supply air pressure to maintain a desired power density.

The primary aim of the present invention is therefore to improve the hand tool used to accomplish the abovementioned objects to such an extent that the sources of error associated with its use be eliminated as much as possible, the handling improved and the working speed is increased. In addition, the asked with the invention available impact wrench with ease of use have the highest possible power density.

These stated objects of the invention are achieved with the subject matters of the independent claims. Features of advantageous developments of the invention will become apparent from the dependent claims.

In order to achieve the above-stated object, the present invention proposes a hand tool with a rotating tool shaft, which is coupled with a hammer mechanism for exercising and / or generating a periodic impact function acting on the tool shaft in the radial direction. The tool shaft of the hand tool is acted upon by compressed air, which ensures the desired rotation at a predeterminable rotational speed and / or with a definable torque. The compressed air usually acts on a turbine, which converts the pneumatic pressure and the pneumatic volume flow into a fast rotation of the tool shaft. At the front end of the tool shaft different tool attachments can be arranged, for example. Screw heads with external or internal hex, so-called. Screw nuts with which particular screw can be tightened or loosened. Other sockets with special fits can also be driven in rotation using the impact wrench.

The hand tool according to the invention requires an actuating element for presetting the various functions of the hand tool and / or for influencing various operating parameters. This actuator is formed according to the present invention by at least one electrical switch. Although the actuator could basically and in a simple construction by an externally arranged on a tool housing or on a tool handle actuating element for manual activation of the rotationally acting pneumatic drive for the tool shaft and / or the radially acting impact function and / or pre-selection of a direction of rotation of the tool shaft be. However, this is by no means restrictive, since in particular an actuating element formed by an electrical switch can also be assigned more complex tasks. Thus, the actuator may also be part of a more complex control electronics or a microprocessor control, in response to various other parameters such as. A torque detection for a Activation, shutdown or reversal can provide. In addition, at least parts of the functions of the hand tool according to the invention can be controlled remotely.

In this case, according to the present invention, at least one pilot-operated 5/3-way valve for activating and controlling the functions of the hand tool is arranged between a compressed air connection of the hand tool and the compressed air drive of the tool shaft. This multi-way valve is operatively connected to the at least one actuating element and controlled by this. Optionally, in the hand tool according to the invention, the 5/3-way valve may be formed by an electromagnetically pilot operated 5/3-way valve. This can be coupled in particular via electrical line connections to the at least one actuating element and thus be controlled by this. However, it is also possible to use feedforward control with piezoelectric actuators or an electromotive feedforward control which can be used e.g. with spindle drives can act on the pilot valves of the 5/3-way valve. Further variants of the precontrol are conceivable and included in the present invention.

The use of the electromagnetically, piezoelectrically or electromotively piloted 5/3-way valve has a particularly advantageous effect both on the air flow and on the construction of the hand tool according to the invention. For example, occur in a combination of 5/2-way valve used as a directional slide and an additional ball seat valve to interrupt the air or pneumatic flow unwanted throttling and resistance losses in the supply line, in the pressure switch and the directional slide, for example the throttle or resistance losses are greater, the more components are in the pneumatic flow or are part of the same. In order to reduce this loss of resistance, which can reduce the output pressure of the pneumatic volume flow by a third or more in the described configuration, it is provided in a first step, the combination of ball seat valve and 5/2-way valve in the hand tool according to the invention by a pilot-controlled 5/3-way valve to replace, which in particular can be dispensed with the installation of a throttling acting ball seat valve, so that there are fewer components in the supply line, ie in the pneumatic flow; This not only simplifies the overall design of the impact wrench according to the invention, but also allows the optimization of the conduction and air flow for the pneumatic volume flow. A mechanical switchover of the compressed air flow is now unrestricted possible, but this is limited to the pilot air, so that there are much more favorable conditions in terms of air flow.

It is now particularly advantageous if the pilot control of the 5/3-way valve is formed by an electromagnetic, piezoelectric or electromotive pilot control, since further advantages can result with regard to the drive logic, the switch arrangement, the controllability and possibly remote controllability. The pilot control lines of the 5/3-way valve can each have electromagnetic and / or piezoelectric or electromotive controls. The actuator for the feedforward control can in a simple construction example eg by at least one electrical switch, switch, a rocker switch, rocker switch, or the like. be formed, optionally also several of these elements or switches or switching elements for different functionalities - here, for example, the direction of rotation reversal for the compressed air drive called - may be provided.

The at least one electrical actuator or switch is normally coupled via electrical leads to the 5/3-way valve which is biased magnetically or otherwise (e.g., piezoelectrically or electromotively); if it is actuated, then a circuit is closed, whereupon the respective magnet located in this circuit or the actuator or drive located in this circuit is actuated, which performs or triggers the desired switching operation. In this way, e.g. the directional slide for the compressed air no longer purely mechanical way, for example. By means of a hand-applied from the side by hand striking motion, are moved to the desired position; instead, the same effect can be triggered by means of a comparatively gentle pressure on an electrical actuator, which triggers the actual displacement of the directional slide via a pilot control. Similarly, these switching functions or at least parts of these switching functions can be taken over by a microprocessor control and / or a (partial) remote control.

This type of operation can bring additional benefits, since by a lateral or rotary impact movement, even if it is performed with little force, the hand tool is deflected or slightly twisted in the direction of the impact and therefore by the user by a corresponding countermovement or holding force must be stabilized again. Such a process requires additional effort and time and consequently reduces the reaction time required for further processing, for example, a wheel change, whereas the same process, it is triggered for example via an electromagnetic pilot control of the 5/3-way valve, the position of the directional slide changed without affecting the position of the hand tool itself noticeably.

Optionally, however, the at least one electrical switch can also be coupled to the directional control valve via differently designed line connections or via radio links, so that the directional control valve can be coupled to the switch via electrical signal lines and can communicate. However, this need not necessarily be formed by a physically existing switch on the device, but can also be a virtual component in a complex controller and / or a remote control, which increases the security against incorrect operations and the switching speed and thus the response times to external changes in state can be reduced. This may, for example, then have a positive effect if the vibrations that normally occur during operation of such a hand tool can lead to impairing the user's reaction or his ability to concentrate.

The electrical energy which is used to supply the circuit and / or to actuate the electromagnetically, piezoelectrically or otherwise precontrolled 5/3-way valve or possibly further existing and hereinafter referred to components (such as, for example, a radio module and / or a microprocessor control ) is required, can either be provided by built-in hand tools batteries or accumulators or via a supply from an external source, for example. By connection to a voltage source, which in turn is connected to the public power grid and which for the switching process the pre-controlled 5/3-way valve and optionally able to provide the available for the operation of other components electrical power. If an external power source for the electrical power supply is to be used, it makes sense to couple the leads for this purpose with the air line, for example. By integration of insulated electrical lines in the outer shell of a compressed air line leading to the impact wrench and is pneumatically coupled with this ,

To control the selected operating mode and / or the correct function, it may be advantageous to equip the hand tool according to the invention with display means which can transmit the corresponding information by optical and / or mechanical and / or acoustic means to the user and possibly other persons. Suitable display means, for example, display window with be mechanically adjustable sliding elements, which may be useful especially when manually operating the directional slide. Lamps, in particular light-emitting diodes, so-called LEDs, which supply the relevant information by means of different colors, flash sequences, or the like, may be particularly suitable. can provide. Display elements with an alphanumeric display function are also conceivable, as well as those which can display a larger amount of information on a display mounted on the device or in this integrated display.

In a further advantageous variant of the hand tool according to the invention, additional intervention options and / or interfaces for more complex controls such as remote control, automatic direction of rotation, automatic shutdown upon reaching an adjustable limit torque, etc. may be provided between or in addition to the at least one actuator, which can be considered in the electrical circuit. In this case, it can be provided, for example, that the more complex control can be coupled with a torque detection which is to be combined particularly advantageously with the device according to the invention, in order thus to open up further possibilities of engagement, e.g. a shutdown after reaching a definable limit torque o. The like.

In this context, it can also be useful to equip the hand tool according to the invention with a control and monitoring device, which can provide the data provided by the hand tool or its sensor system, which may be in the form of voltage values, pulse numbers, revolution numbers, time values, etc. evaluates. For this purpose, it is assumed that the hand tool has the sensors required for the detection and transmission and the transmission means required for the transmission of the determined data. The control and monitoring device itself is usually formed by a microcontroller unit, which evaluates the available data and transferred in convertible for the existing actuators control commands.

Alternatively or additionally, the hand tool according to the invention can be connected to an external control and / or control device via a wired and / or wireless path, which converts the data transmitted by the hand tool or its sensor into a form that can be evaluated for further processing, and in this way generally accessible by software evaluation. If necessary, the control commands resulting from the evaluation can then be returned in the same way to the hand tool or its actuators according to the invention and / or external, with the hand tool by electrical, optical or pneumatic cables and / or lines of connected devices are transmitted and executed by them.

Furthermore, it may be provided that the data transmitted to the external control and / or monitoring device is stored in and stored there for further evaluation, starting from a larger database.

It may also be possible that conclusions are derived from a directly performed evaluation, which conclusions can lead directly and / or subsequently to the same and / or different courses of action. Thus, for example, the determination of a limit torque may be provided, beyond which the impact wrench according to the invention receives a stop command from the integrated or external control unit and as a result terminates the tightening or loosening process. By combining with another parameter, e.g. the number of revolutions of the tool shaft required for the respective operation, further decision patterns can be derived and defined, e.g. a speed and / or torque control, reverse rotation and much more.

Starting from one of the abovementioned possibilities or a combination of several of the above, it may now be that components which were previously indispensable for the operation of the impact wrench and therefore were an integral part of the overall design, now flexible in or on the impact wrench or even can be arranged away from it; In particular, it may also be that suitable mechanical components can be replaced by electronic components and / or switching commands. So it may be possible, for example, that the adjustment of the direction of rotation of the tool shaft can be made in various ways, whether by installing a corresponding mechanical switch o.ä. in the impact wrench itself, by incorporating an electronic switch / button in the device, by providing the function of an external device such as a foot switch and / or by transmitting the choice of the direction of rotation by an external control and / or control device, so that the choice the direction of rotation of the tool shaft manually by the operator of the hand tool and / or automated by a control and / or monitoring device, possibly also - depending on other influencing parameters - can be made by both.

This type of control makes it possible to automate work processes partially or even almost completely. For example. the external control and / or monitoring device can determine the successful loosening of a screw via suitable parameters, such as measuring the number of revolutions of the tool shaft, or the like, determining the torque, measuring a time interval, etc., automatically switch off the hand tool and set the direction of rotation Select "Tighten" without the operator having to act for this purpose. The latter can therefore already prepare for the "tightening process" and start the process as soon as the prerequisites have been met. Likewise, the end of this process can now be determined, e.g. by reaching a predetermined torque, whereupon the hand tool can be switched off automatically. It is also possible that the shutdown of the tool immediately after tightening the screw can serve as a signal to release the vehicle without the operator of the tool must be active in this regard.

• Fig. 1 zeigt eine schematische Ansicht einer Ausführungsvariante eines erfindungsgemäßen Schlagschraubers.
• Fig. 2 zeigt ein schematisches Schaltbild einer ersten Variante eines Ventils zur Steuerung des Schlagschraubers gemäß Fig. 1.
• Fig. 3 zeigt ein schematisches Schaltbild einer zweiten Variante eines Ventils zur Steuerung des Schlagschraubers gemäß Fig. 1.
• Fig. 4 zeigt ein schematisches Schaltbild einer dritten Ausführungsvariante einer Steuerung für den Schlagschrauber.

In the following, embodiments of the invention and their advantages with reference to the accompanying figures will be explained in more detail. The proportions of the individual elements to one another in the figures do not always correspond to the actual size ratios, since some shapes are simplified and other shapes are shown enlarged in relation to other elements for better illustration.

• Fig. 1 shows a schematic view of an embodiment of an impact wrench according to the invention.
• Fig. 2 shows a schematic diagram of a first variant of a valve for controlling the impact wrench according to Fig. 1 ,
• Fig. 3 shows a schematic diagram of a second variant of a valve for controlling the impact wrench according to Fig. 1 ,
• Fig. 4 shows a schematic diagram of a third embodiment of a controller for the impact wrench.

For identical or equivalent elements of the invention, identical reference numerals are used. Furthermore, for the sake of clarity, only reference symbols are shown in the individual figures, which are required for the description of the respective figure. The illustrated embodiments are merely examples, such as Device according to the invention can be configured and do not represent a final limitation.

The schematic representation of Fig. 1 shows a possible practical embodiment of a hand tool according to the invention using the example of a striking screwdriver 10 having a rotatably acting compressed air drive in a housing 12, with which a front side led out of the housing 12 tool shaft 14 can be set in rotation. In the exemplary embodiment shown, the tool shaft 14 has a square fit 16 for attaching commercially available tool attachments (not shown), which, for example, can have a customary customs measure. On a lower side of the elongated tool housing 12 is a pistol-like handle 18, which allows Einhandführung and operation of the impact wrench 10. Within the housing 12 is still a hammer mechanism, not shown here, which serves to generate or exercise a force acting in the direction of rotation on the tool shaft 14 periodic impact function. Possibly. the impact function of the impact mechanism can be switched off.

On the handle 18 is still a in the representation of Fig. 1 designed as a probe element actuating element 20 is provided with the manual intervention or preselection of the rotationally acting pneumatic drive for the tool shaft 14 and / or the radially acting impact function and / or the preselection of a direction of rotation of the tool shaft 14 can be activated or adjusted. The actuating element 20 or the actuating elements 20 may be formed, for example, as a pressure switch, as a slide switch o. The like., Which are coupled via electrical connection lines with a controller for the impact wrench 10. The further actuating element 21 arranged behind the handle 18 at a lower region of the rear end side of the housing 12 may be a direction-of-rotation switch. The presentation of the Fig. 1 This is based on the configuration of conventional impact wrenches, which have a mechanical slide switch to select the direction of rotation. However, it should be stressed at this point that only a simple variant, which in Fig. 2 is shown as a circuit diagram, has such a or similar slider, whereas electrical or microprocessor-controlled direction switches or a configuration according to Fig. 3 do not need such an actuator 21. Therefore, it should be noted that the hand tool or the impact wrench 10 in such an embodiment (eg according to Fig. 3 ) will not have such a slider on the housing 12, but either a smaller or less obvious switch or not from the outside recognizable switching element, since its functions are taken over by the microprocessor control or eg by a radio remote control.

At a bottom of the gun-like handle 18 is a compressed air connection 22 to the compressed air supply of the impact wrench 10 via a compressed air line 24, which may be, for example. With a stationary or mobile pressure supply such as a compressor or optionally also a refillable pressure accumulator (not shown).

In the embodiment shown is located on one of the lead-out tool shaft 14 with the square fit 16 opposite rear face of the housing 12, for example, electromagnetically or piezoelectrically or otherwise piloted 5/3-way valve 26 for activation and control of the functions of the hand tool or Impact wrench 10, which is operatively connected to the at least one actuating element 20 and / or the further actuating element 21 and can be controlled by this. According to the present invention, the control valve is a pilot-operated 5/3-way valve 26, which via electrical line connections to the at least one actuating element 20 and / or with the further actuating element 21 or with other switching elements (see Fig. 4 ) is coupled, so that the tool shaft 14 is set in rotation by a manual or automated actuation of the switch or actuator 20 and / or 21 in previously preselected rotational direction.

The valve can also be a simply pilot operated, for example, a pneumatically pilot operated 5/3-way valve 28, as it is in the Fig. 2 is shown in its meaningful interconnection as the simplest embodiment variant of a function control for the impact wrench 10. Here, the further actuator 21 is useful as a manual direction of rotation slide formed on the in Fig. 1 seat shown and is functionally and spatially associated with the valve 28. The switch on the handle 18, that is, the first actuator 20 acts as a slide, seat or ball valve o. The like., Or as a release switch, coupled with an electrical control for switching on or off the supply pressure for driving the impact wrench 10 is.

The schematic representation of Fig. 2 shows a simplest embodiment of a wiring of a 5/3-way valve 28 with pneumatic actuation or precontrol, as in the impact wrench 10 according to the invention in principle to Use can come. As can be seen from the circuit diagram, the control switch 40 is located in the control pressure line 48, which at the same time illustrates the impending throttle losses which such an arrangement entails. The main pressure line not shown here goes through the handle of the impact wrench 10 (see. Fig. 1 ) and opens centrally at the 5/3-way valve 28, namely at the central main pressure port P.

The above recognizable direction of rotation switch is formed by the second actuator 21, which connects the pilot lines 49 for the pilot control of the 5/3-way valve 28 shown with the control pressure line 48. The 5/3-way valve 28 is in accordance with Fig. 2 switched mechanically or pneumatically. The direction of rotation switch or the second actuator 21 is a pure switch that pressurizes one of the two pilot lines 49 and blocks the other pilot line 49, so that the control piston 44 is pressed in the appropriate direction, resulting in the connection diagram shown below for a Standstill or for one of the two directions of rotation of the drive motor of the impact wrench 10 results.

Although the advantage of such a configuration is that all switching functions are controlled purely pneumatically, so that can be dispensed with an additional electrical power supply. However, the control switch 40 in the control pressure line 48 and the switch 21 can bring disadvantages in the form of throttling losses, which, depending on the configuration, make it necessary to work with higher overall pneumatic pressures in order to compensate for the throttling losses.

The presentation of the Fig. 3 illustrates the interconnection of an electromagnetically piloted 5/3-way valve 26 for controlling the rotating tool shaft 14 of the impact wrench 10. As mentioned, the 5/3-way valve 26 may have an electromagnetic, a piezoelectric, an electric motor or otherwise acting pilot control 30. The circuit diagram of such a 5/3-way valve 26 is indicated below the sectional view of the valve 26; There it can be seen that it is a valve 26 with three switching positions and a total of five different pressure connections to be interconnected, whereby both the activation of the rotary drive and its direction of rotation is possible. Above the sectional view of the valve 26 electrical switching symbols of the actuating element 20 are indicated, which via an electrical connection to the pilot control 30 of the valve 26 is a preselection of the direction of rotation as well as enable and disable the rotary drive of the impact wrench 10.

Like the upper part of the Fig. 3 can be seen with the electrical circuit components, the 5/3-way valve 26 requires only a very few components that can form the actuator 20 in their entirety. These are an electrical power supply, for example in the form of a battery or a rechargeable battery, a push button for activating the compressed air drive, which is coupled to the pilot control 30 of the 5/3-way valve 26 and cooperates with this. In addition, a switch for the direction of rotation is required, which may be formed as in the embodiment shown by a simple electrical switch.

The presentation of the Fig. 4 illustrates a more advantageous further expansion stage of the impact wrench 10 according to the invention, which is particularly well suited for wiring with a microprocessor controller 32 due to its electrical pilot control 30 for the 5/3-way valve 26. This can not only provide an interface 34 to a CAN bus, but also take over all other switching and / or shutdown functions (wiring 36), including an automatic shutdown upon reaching or exceeding a definable limit torque. Also radio links to a central monitoring station is made possible by such a microprocessor controller 32. Thus, numerous other functions are conceivable, such as logging of the occurring moments, automatic shutdown, speed control, etc.

Defined target torques allow, if necessary, central monitoring and / or influencing from a remote control or control center or control room.

The invention has been described with reference to a preferred embodiment. However, it will be apparent to those skilled in the art that modifications or changes may be made to the invention without departing from the scope of the following claims.

LIST OF REFERENCE NUMBERS

10

Impact wrench, hand tools

12

Housing, tool housing

14

tool shaft

16

Vierkantpassung

18

Handle, tool handle

20

Actuator, switch

21

further actuator, reversal of direction of rotation

22

Compressed air connection

24

Compressed air line

26

5/3-way valve (electromagnetically, piezoelectrically or similar pre-controlled)

28

5/3-way valve (simply pre-controlled)

30

feedforward

32

microprocessor control

34

interface

36

further wiring

40

control switch

44

spool

48

Control pressure line

49

pilot line

Claims (13)

1. A hand tool (10) operated by compressed air, with a rotating tool shaft (14), said tool shaft (14) being coupled with a striking mechanism for generating or, as the case may be, for exerting a striking function acting periodically upon the tool shaft (14) in a radial direction, with at least one actuation element (20) for the manual activation of the rotatorily acting compressed-air drive of the tool shaft (14) and/or for the radially acting striking function and/or for the preselection of a direction of rotation of the tool shaft (14), characterised in that at least one servo-assisted 5/3-way directional control valve (26) for the activation and for the control of the functions of the hand tool (10) is disposed between a compressed-air connection (22) of the hand tool (10) and the compressed-air drive of the tool shaft (14), with the servo-assisted 5/3-way directional control valve (26) being operatively connected to and being controllable by or, as the case may be, via the at least one actuation element (20); and in that the at least one actuation element (20) is formed by at least one electrical switch.
2. The hand tool as recited in claim 1, in which the servo-assisted 5/3-way directional control valve (26) is servo-assisted electromagnetically or piezoelectrically or electromotively.
3. The hand tool as recited in claim 2, in which the servo lines of the 5/3-way directional control valve (26) each have electromagnetic and/or piezoelectric controls or, as the case may be, servo-controls (30).
4. The hand tool as recited in one of the claims 1 to 3, in which the actuation element (20) is disposed at the hand tool (10), in particular at a tool handle (18).
5. The hand tool as recited in one of the claims 1 to 3, in which the actuation element (20) is coupled with an electronic circuit and/or with a microprocessor control (32).
6. The hand tool as recited in one of the claims 1 to 5, in which further possibilities for intervention and/or interfaces for more complex controls (32), which are taken into account in the electrical circuit, are disposed between the at least one actuation element (20) and the 5/3-way directional control valve (26).
7. The hand tool as recited in claim 6, in which the more complex control (32) is coupled with an existing torque acquisition implemented in the hand tool (10).
8. The hand tool as recited in claim 6 or 7, in which the actuation element is part of the more complex control and/or of the microprocessor control (32) and provides for an activation, a deactivation, or a reversal of rotation direction based on the torque acquisition.
9. The hand tool as recited in one of the claims 5 to 8, in which the more complex control or the microprocessor control (32) interacts with a reversal of rotation direction for the compressed-air drive of the tool shaft (14), with the reversal of rotation direction being coupled to or, as the case may be, being actuatable by the 5/3-way directional control valve (26).
10. The hand tool as recited in one of the claims 1 to 9, comprising a control device and/or regulating device, in particular in the form of a microcontroller, with the control device and/or regulating device evaluating the data provided by the hand tool (10) or, as the case may be, by a sensor system.
11. The hand tool as recited in claim 10, in which the selection of the direction of rotation of the tool shaft (14) is specifiable manually by the user of the hand tool (10) and/or automatedly by the control device and/or regulating device.
12. The hand tool as recited in one of the claims 7 to 11, in which the striking function and/or the drive of the tool shaft (14) is/are coupled with the torque acquisition such that at least one of the functions is automatically deactivatable upon a prespecifiable limit torque being reached.
13. The hand tool as recited in one of the claims 5 to 12, in which the more complex control or the microprocessor control (32) is coupleable and/or controllable with a control centre and/or monitoring centre by way of a wireless data connection.

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