EP3047943A2 - Power screwdriver - Google Patents

Abstract

In a rotary wrench with a motor (3) for generating a torque, a tool holder (9), which is in operative engagement with the motor (3) and transmits the generated torque to a tool, a measuring device (7), the continuously at least one measured variable For determining the torque and the measured value passes, a control device (12) which is in communication with the motor (3) and the measuring device (7) and controls the operation of the motor (3) so that after starting it continuously generates increasing torque, and the engine shuts off when a target measured value, the measuring device is a torque sensor (7) and the torque sensor (7) between the motor (3) and the tool holder (9).

Description

The invention relates to a rotary wrench with a motor for generating a torque, further comprising a tool holder, which is in operative engagement with the motor and transmits the generated torque to a tool, a measuring device which continuously measures at least one measured variable for determining the torque and transmits the measured value, and with a control device which is in communication with the engine and the measuring device and controls the operation of the motor so that it generates a continuously increasing torque after its start, and the motor turns off when a desired measured value is reached.

Screwdrivers are used to tighten the nuts in screw connections. In the fully assembled screw connection, the nut should be tightened with a desired or required setpoint torque. This setpoint torque is predetermined for the control device of the rotary screwdriver, for example via an adjusting device present on the rotary screwdriver and operable by the operator. If the engine is then started, the nut to be tightened is turned on, with the tightening torque of the nut rising continuously. The setpoint torque is stored in a control software in a table function based on a referencing between the setpoint torque and the motor current. Since the motor current increases with increasing tightening torque, a referenced motor current is assigned to each setpoint torque to be set. The motor current is continuously measured by a measuring device and forwarded to an evaluation unit. When the motor current assigned to the setpoint torque is reached, the control unit receives a switch-off signal from the evaluation unit and switches off the motor. The target torque is therefore also referred to as shutdown torque. The difference between the actually achieved actual torque at which the engine has been switched off by the control device and the predetermined setpoint torque can still be relatively large.

The invention is therefore based on the object to improve a rotary wrench of the type mentioned so that the target torque is achieved with greater accuracy.

According to the invention this object is achieved in a generic screwdriver in that the measuring device is a torque sensor and the torque sensor between the engine and the tool holder is arranged.

The inventive measures the torque generated by the engine is measured directly and used to generate the shutdown signal. The control device switches Therefore, the engine at a directly measured directly from without immediate torque, whereby a difference to the predetermined target torque can be significantly reduced. In this way, an indirect measurement of the torque and the associated inaccuracy is avoided.

Preferably, the torque sensor is arranged near the tool holder. The closer the torque sensor is arranged to the tool that is to apply the torque to the screw connection, the more accurately the actually applied torque can be measured. For example, the torque sensor can be arranged directly in front of a power take-off square forming the tool holder in the output direction. A nut for tightening the nuts is attached to the output square, so that an immediately attached torque sensor is located in the immediate vicinity of the nut, which is rotated with the tightening torque.

In a favorable embodiment of the invention, a planetary gear between the engine and tool holder is arranged, which is in operative engagement with both, and the torque sensor is part of the planetary gear. Screwdrivers with planetary gears are used to tighten the nuts in large screw connections - starting with M12. The torques used start at about 150 Nm and reach up to 13,000 Nm. In order to generate these torques, the motor drives a planetary gear, at the end of which the tool holder is located, for example, a drive square, on which a Aufstecknuss is adapted. Is the torque sensor part of the planetary gear, it can be accommodated in a space-saving, which allows a relatively simple manufacture and installation of the rotary screwdriver.

In addition, the torque sensor is housed within the screwdriver housing and thus largely protected from damage in this case.

But it is also possible to arrange the torque sensor in another embodiment of the invention on the outside of the screwdriver housing. The torque sensor is then readily accessible and can be easily replaced in the event of damage.

Preferably, the engine is an electric motor. Electric motors require only a power connection for power supply and are low maintenance and relatively light. The transport and handling of the screwdrivers are simplified.

In an advantageous embodiment of the invention, the torque sensor and the control device are connected to an evaluation unit, to which the torque sensor transmits the measured torques and from which the control device reaches a setpoint torque a shutdown signal for switching off the engine receives. In the evaluation unit, a comparison of the generated torque with the target torque takes place. A separate embodiment and arrangement of the evaluation unit makes these independent of the design and arrangement of the torque sensor and / or the control device, so that the evaluation unit, torque sensor and control device can be optimally designed and placed individually.

Preferably, the evaluation unit is arranged outside of the rotary screwdriver. In this way, the measured torques of several in-use screwdriver can be evaluated centrally in a common evaluation. It is also possible to arrange the evaluation unit in the screwdriver.

In a preferred embodiment of the invention, the screwdriver has a wireless data transmission connection between the torque sensor and the evaluation unit and / or between the evaluation unit and the control device and / or between the control device and the motor. In a screwdriver then no cable channels must be formed and no cables are mounted, whereby the cost of manufacture and assembly of the screwdriver is significantly reduced.

Advantageously, an inventive screwdriver has a data output for receiving the measured torques and for their transmission to an external data carrier. The measured torques and other data, such. As associated times, can be made available in this way for archiving or optionally for a more extensive, for example, statistical, evaluation.

In this case, this data output is preferably configured to transmit the measured torques wirelessly to an external data carrier. This also avoids the formation of cable channels and the installation of cables, which further reduces the cost of manufacturing and assembly of the screwdrivers.

In an advantageous development of the invention, the data output is set up to transmit the measured torques to an evaluation unit wirelessly, to receive the shutdown signal from the evaluation unit and to transmit this to the control unit in order to switch off the motor. The evaluation unit can be z. B. in a computer, which communicates with the data output in data transmission connection. In this embodiment, the data output is also used as data input. As a result, the design and manufacture of a rotary screwdriver with wireless data transmission can be further simplified.

Figur 1

eine Seitenansicht einer ersten Ausführungsform eines erfindungsgemäßen Drehschraubers;

Figur 2

Detail II aus Figur 1;

Figur 3

Detail III aus Figur 1;

Figur 4

eine Seitenansicht einer zweiten Ausführungsform eines erfindungsgemäßen Drehschraubers;

Figur 5

eine Seitenansicht einer dritten Ausführungsform eines erfindungsgemäßen Drehschraubers;

Figur 6

eine Seitenansicht einer vierten Ausführungsform eines erfindungsgemäßen Drehschraubers;

Figur 7

eine teilweise aufgeschnittene Seitenansicht des Vorderteils des Drehschraubers aus Figur 1, mit einer ersten Ausführungsform eines Drehmomentsensors;

Figur 8

Detail VIII aus Figur 7;

Figur 9

eine der Figur 7 ähnliche Seitenansicht, mit einer zweiten Ausführungsform eines Drehmomentsensors;

Figur 10

Detail X aus Figur 9;

Figur 11

eine Seitenansicht des Vorderteils eines Drehschraubers aus den Figuren 4, 5 oder 6, mit einer dritten Ausführungsform eines Drehmomentsensors;

Figur 12

Detail XII aus Figur 11.

The invention will be explained in more detail by way of example with reference to the drawings. Show it:

FIG. 1

a side view of a first embodiment of a rotary wrench according to the invention;

FIG. 2

Detail II off FIG. 1 ;

FIG. 3

Detail III off FIG. 1 ;

FIG. 4

a side view of a second embodiment of a rotary screwdriver according to the invention;

FIG. 5

a side view of a third embodiment of a rotary screwdriver according to the invention;

FIG. 6

a side view of a fourth embodiment of a rotary screwdriver according to the invention;

FIG. 7

a partially cutaway side view of the front part of the rotary screw FIG. 1 with a first embodiment of a torque sensor;

FIG. 8

Detail VIII off FIG. 7 ;

FIG. 9

one of the FIG. 7 similar side view, with a second embodiment of a torque sensor;

FIG. 10

Detail X off FIG. 9 ;

FIG. 11

a side view of the front part of a rotary from the FIGS. 4 . 5 or 6 with a third embodiment of a torque sensor;

FIG. 12

Detail XII off FIG. 11 ,

The embodiments of a rotary wrench 1 according to the invention shown in the figures have in succession a handle 2, a motor 3, a rotary joint 4, a 5, a planetary gear 6 with a torque sensor 7 and a support arm 8 and a driven square 9 with plugged Aufstecknuss 10 , In the stated order, the components are fastened to each other, wherein the torque sensor 7 and the support arm 8 are fixed to the planetary gear 6.

The motor 3 is an electric motor and is powered by the handle 2, to which a power cord 11 is attached. However, the screwdriver 1 may also have a battery for power.

In the handle 2 is a control device 12 ( FIG. 2 ), which controls the operation of the motor 3. The control device 12 is set up to control the operation of the electric motor 3 in such a way that it generates a continuously increasing torque after its starting. Furthermore, the control device 12 is configured to receive a switch-off signal from an evaluation unit 13 and to switch off the motor 3 upon receipt of the switch-off signal. On the upper side of the handle 2, a display 14 and an input device 15 are arranged ( FIG. 2 ) connected to the controller 12. At the input device 15, the target or shut-off torque can be entered, when it reaches the controller 12 to turn off the engine.

Control device 12, display 14 and input device 15 are housed in a common electronic component 16.

Furthermore, the handle 2 has a data output 17 (FIG. FIG. 3 ), which is at least likewise connected to the control device 12 and also to the torque sensor 7. An external data carrier 17a, for example a computer with data carrier, can be connected to the data output 17. About the data output 17 z. B. the measured torques and the Abschaltuhrzeit be issued.

With the help of the rotary joint 4 between the motor 3 and 5 reversing motor 3 and handle 2 can be rotated relative to the remaining part of the rotary wrench 1 in order to bring the handle 2 in a comfortable and safe working position.

With the help of the change gear 5, the operation of the rotary wrench 1 between an overdrive and a load gear can be switched back and forth. For this purpose, the change gear 5 has a rotary switch 18. In overdrive, you can work at maximum speed with reduced torque. In contrast, in the load gear with maximum torque at reduced speed can be worked.

The planetary gear 6 is used to generate high torques, for example 150 Nm to 13,000 Nm. On its input or drive side, the planetary gear 6 is driven by the motor 3. On its output or output side there is an output shaft 19 to which the output square 9 is fixed, on which the replaceable Aufstecknuss 10 is attached.

In the circumferential direction around the output shaft 19 extends around as a closed ring of the torque sensor 7, which in conjunction with the FIGS. 7 to 12 will be described in more detail.

On the output shaft 19 of the support arm 8 is fixed, wherein between the output shaft 19 and support arm 8, a sliding bearing 20 is arranged. The support arm 8 is supported on the bolting construction or on adjacent bolts to produce the counter-torque. At the in FIG. 1 illustrated embodiment, the evaluation unit 13 is arranged in the handle 2 of the rotary screwdriver 1. This in FIG. 2 The evaluation unit 13 receives the measured torques from the torque sensor 7, compares them with the setpoint torque and outputs a shutdown signal to the control device 12 when the setpoint torque is reached.

In the interior of the rotary screw 1 laid power and data cable 21 connect torque sensor 7, evaluation unit 13, control device 12 and data output 17 with each other. Furthermore, 17 data can be output wired at the data output.

At the in FIG. 4 illustrated embodiment, the evaluation unit 13 is also arranged in the screwdriver 1, however, the data transfer between the torque sensor 7, evaluation unit 13 and control device 12 by a wireless connection 22. In contrast, the data are still provided at the data output 17 via running in the screwdriver 1 power and data cable and The data can be output via cable at the data output 17.

At the in FIG. 5 illustrated embodiment, the evaluation unit 13 is arranged outside the rotary wrench 1 and consists as in the embodiment according to FIG. 4 a wireless communication link 22 between the torque sensor 7 and the controller 12. However, in the embodiment of FIG FIG. 5 between the control device 12 and the evaluation unit 13, a wireless connection and the data output 17 for the wired data output replaced by a data output 17 for a wireless data output.

At the in FIG. 6 illustrated embodiment, the (not shown) evaluation unit is arranged outside the rotary wrench 1 and carried out as in the embodiment according to FIG. 5 All data transmissions via wireless data transmission connections 22, however, the measured torques are transmitted directly from the torque sensor 7 wirelessly to the external evaluation unit. When the desired torque is reached, the evaluation unit wirelessly transmits the switch-off signal to the control device 12 present in the rotary screwdriver 1, which then switches off the engine 3. This in FIG. 2 illustrated electronic component 16 contains in this case only the control device 12, the display 14 and the input or adjustment 15 for inputting the desired torque.

It is also intended to set up the data output 17 to transmit the measured torques, preferably wirelessly, to an evaluation unit 13, receive the shutdown signal from the evaluation unit 13 and then transmit the shutdown signal to the control unit 12 so that it shuts off the motor 3.

In FIG. 7 is the front part of the screwdriver 1 off FIG. 1 shown with the front part of the planetary gear 6, the torque sensor 7, the support arm 8 and the output square 9 with Aufstecknuss 10 in a partially cutaway side view. The double arrows marked "M" indicate the direction of rotation of the torque.

In FIG. 8 the detail VIII is shown on an enlarged scale.

In the in the FIGS. 7 and 8 In the illustrated embodiment, the torque sensor 7 is arranged on the outside of the screwdriver housing 23 and connected via a cable connection 21 at least to the evaluation unit 13 and the data output 17. The cables 21 extend in a cable channel 24 in the wall of the screwdriver housing 23.

In the outer wall 25 of the output shaft 19 extend in the circumferential direction two mutually parallel rows, each having a plurality of longitudinally extending the output shaft 19 elongated recesses 26. The recesses 26 of the two rows are opposite to each other in the longitudinal direction of the output shaft 19 at a predetermined distance and are arranged in the circumferential direction at a constant distance from each other.

In the recesses 26 elements 27 are arranged, which respond to a twisting of the output shaft 19. Such elements 27 may be, for example, magnets, opto-electronic elements or strain gauges.

In the exemplary embodiments illustrated here, the recesses 26 contain magnets 27.

Between the output shaft 19 and the screwdriver housing 23 and thus also between the magnets 27 and the screwdriver housing 23, a sliding bearing 20 is arranged to ensure a low-friction rotation of the output shaft 19 in the screwdriver housing 23.

The torque sensor 7 measures magnetic field changes that occur in the magnets 27 due to the torsion of the output shaft 19 when generating the torques and also change with the change of the torque.

The distance 28 between the output shaft 19 facing side of the torque sensor 7 and the outer wall 25 of the output shaft 19 and the magnets 27 disposed therein is so small that a perfect torque measurement is ensured. The strength of the screwdriver housing 23 is adjusted accordingly in this area.

The FIG. 9 with representation of the detail X in FIG. 10 shows one of the FIG. 7 similar representation of another embodiment of a rotary screwdriver according to the invention 1. In which in the FIGS. 9 and 10 illustrated embodiment, the torque sensor 7 is disposed within the screwdriver housing 23 and is located with a small air gap 29, the magnet 27 of the output shaft 19 opposite. The data transmission, z. As to the evaluation unit 13 and the data output 17, also takes place here via cable 21, which extend in a cable channel 24 in the screwdriver housing 23.

Also the FIGS. 11 and 12 show in similar representations as in the FIGS. 7 to 10 a further embodiment of a rotary screwdriver according to the invention 1. As in the embodiment according to the FIGS. 7 and 8 Here, too, the torque sensor 7 is arranged on the outside of the screwdriver housing 23. The data transmission, z. B. to the evaluation unit 13 and the data output 17, but in this embodiment is wireless. For this purpose, a transmitter 30 is arranged in the screwdriver housing 23, which communicates with the torque sensor 7 via a data line 31 and transmits the measured torques wirelessly. The evaluation unit can be located in the screwdriver 1 or be accommodated externally.

Claims (11)

Wrench with
a motor for generating a torque,
a tool holder, which is in operative engagement with the motor and transmits the generated torque to a tool,
a measuring device which continuously measures at least one measured quantity for determining the torque and forwards the measured value,
a control device which is in communication with the engine and the measuring device and controls the operation of the engine so that it generates a continuously increasing torque after it has started, and the engine shuts off the engine when a desired measured value is reached,
characterized in that
the measuring device is a torque sensor (7) and the torque sensor (7) is arranged between the motor (3) and the tool holder (9). Screwdriver according to claim 1, characterized in that the torque sensor (7) is arranged near the tool holder (9). Screwdriver according to claim 1 or 2, characterized in that a planetary gear (6) between the motor (3) and tool holder (9) is arranged and is in operative engagement with both and the torque sensor (7) is part of the planetary gear (6). Screwdriver according to claim 1 or 2, characterized in that it comprises a screwdriver housing (23) and the torque sensor (7) on the outside of the screwdriver housing (23) is arranged. Screwdriver according to one of the preceding claims, characterized in that the motor (3) is an electric motor. Screwdriver according to one of the preceding claims, characterized in that the torque sensor (7) and the control device (12) are in communication with an evaluation unit (13), to which the torque sensor (7) passes the measured torques and from which the control device (12 ) Upon reaching a desired torque, a shutdown signal for switching off the engine (3) receives. Screwdriver according to claim 6, characterized in that the evaluation unit (13) outside of the rotary screwdriver (1) is arranged. Screwdriver according to one of the preceding claims, characterized by a wireless data transmission connection (22) between torque sensor (7) and evaluation unit (13) and / or between evaluation unit (13) and control device (12) and / or between control device (12) and motor (3). Screwdriver according to one of the preceding claims, characterized by a data output (17) for receiving the measured torques and transmitting them to an external data carrier (17a). Screwdriver according to claim 9, characterized in that the data output (17) is adapted to transmit the measured torques wirelessly to an external data carrier (17a). Screwdriver according to claim 9 or 10, characterized in that the data output (17) is adapted to transmit the measured torque wirelessly to an evaluation unit (13) to receive from the evaluation unit (13) the switch-off signal and to transmit it to the control device to shut off the engine (3)

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