DE102018201074A1 - Method for controlling an impact wrench - Google Patents

Abstract

Method for controlling a hand tool, in particular an impact wrench achieved. The impact wrench has a motor with an input spindle and a Ausgansspindel, the motor is the input spindle in rotation and the output spindle is connected to a tool holder. Furthermore, the impact wrench has an anvil rotatably connected to the output spindle and a hammer. The hammer is connected to the input spindle such that it performs intermittent movement in the axial direction of the input spindle as well as intermittent rotational movement about the input spindle due to the rotational movement of the input spindle. Further, the hammer intermittently strikes the anvil in this manner, thereby delivering a beat and angular momentum to the anvil and thus to the output spindle. In this case, the method comprises the steps according to the invention. Furthermore, a handheld power tool, in particular an impact wrench, is disclosed with a control unit disclosed, wherein the control unit is designed for carrying out a method according to the invention.

Description

The invention relates to a method for controlling a hand tool, in particular an impact wrench, and a hand tool, in particular an impact wrench for performing the method.

State of the art

Impact wrenches for tightening screw elements, such as threaded nuts and screws are known from the prior art. A percussion drill of this type includes, for example, a structure in which an impact force in a rotational direction is transmitted to a screw member by a rotational impact force of a hammer. The percussion drill having this structure includes a motor, a hammer to be driven by the motor, an anvil hit by the hammer, and a tool. In the percussion drill, the motor built into a housing is driven, the hammer driven by the motor, the anvil in turn struck by the revolving hammer, and an impact force delivered to the tool. Impact wrenches generate a high repetition rate of impact torque due to their impact.

For example, from the EP 2 650 085 A2 an electronic clutch for impact wrench known. The coupling has a current sensor for the motor and a sensor for the motor speed. In addition, the device has a control unit that defines a limiting current based on a clutch setting.

Often it proves to be disadvantageous that the torque generated for the fasteners used, such as Phillips screws, is too high, whereby the tool loses contact with the screw head and the screw heads are damaged.

Disclosure of the invention

The object of the invention is to provide a simple method for controlling a hand tool, in particular a impact wrench, whereby the range of application of the impact wrench is widened and a more controllable behavior of the impact wrench at high torques, for example when sunk screws is possible.

This object is achieved by means of the subject matter of the independent claims. Advantageous embodiments of the invention are the subject of each dependent subclaims.

1. a. Start eines Anschlagmodus durch eine entsprechende Benutzerauswahl;
2. b. Betreiben des Motors in einer ersten Motordrehrichtung, wobei die erste Motordrehrichtung mit einem Eindrehen einer Schraube durch die Ausgangsspindel korrespondiert;
3. c. Fortlaufendes Bilden eines Differenzwertes einer Motorgeschwindigkeit zwischen einem ersten Zeitpunkt und einem darauffolgenden zweiten Zeitpunkt;
4. d. Überwachen des Differenzwertes der Motorgeschwindigkeit daraufhin, ob er einen festgelegten ersten Grenzwert unterschreitet, wobei der erste Grenzwert den Vorgang des Aufsetzens eines Schraubenkopfes auf ein Werkstück repräsentiert;
5. e. Umkehren der Motordrehrichtung des Motors als Folge des Unterschreitens des ersten Grenzwertes des Differenzwertes der Motorgeschwindigkeit und Betreiben des Motors in einer zweiten Motordrehrichtung, wobei die zweite Motordrehrichtung umgekehrt zur ersten Motordrehrichtung ist;
6. f. Überwachen einer Motorgeschwindigkeit des Motors daraufhin, ob die Motorgeschwindigkeit einen festgelegten zweiten Grenzwert der Motorgeschwindigkeit überschreitet;
7. g. Überwachen eines Motordrehwinkels des Motors daraufhin, ob der Motordrehwinkel einen festgelegten dritten Grenzwert des Motordrehwinkels überschreitet;
8. h. Umkehren der Motordrehrichtung des Motors als Folge des Überschreitens des zweiten Grenzwertes durch die Motorgeschwindigkeit und des dritten Grenzwertes durch den Motordrehwinkel; und
9. i. Fortsetzen des Verfahrens ab Punkt b) solange, wie die Benutzerauswahl aktiv ist.

According to the invention, a method for controlling a handheld power tool, in particular an impact wrench, is disclosed. The impact wrench has a motor with an input spindle and a Ausgansspindel, the motor is the input spindle in rotation and the output spindle is connected to a tool holder. Furthermore, the impact wrench has an anvil rotatably connected to the output spindle and a hammer. The hammer is connected to the input spindle such that it makes intermittent movement in the axial direction of the input spindle as well as an intermittent rotational movement about the input spindle due to the rotation of the input spindle. Further, the hammer intermittently strikes the anvil in this manner, thereby delivering a beat and angular momentum to the anvil and thus to the output spindle. The method comprises the steps:

1. a. Start a stop mode by a corresponding user selection;
2. b. Operating the motor in a first direction of motor rotation, the first direction of motor rotation corresponding to threading a screw through the output spindle;
3. c. Continuously forming a difference value of a motor speed between a first time and a subsequent second time;
4. d. Monitoring the difference value of the motor speed as to whether it falls below a predetermined first limit value, the first limit value representing the process of placing a screw head on a workpiece;
5. e. Reversing the engine rotational direction of the engine as a result of the first limit of the differential value of engine speed being undershot and operating the engine in a second engine rotational direction, the second engine rotational direction being inverse to the first engine rotational direction;
6. f. Monitoring an engine speed of the engine for whether the engine speed exceeds a predetermined second engine speed limit;
7. G. Monitoring a motor rotation angle of the motor to determine whether the motor rotation angle exceeds a predetermined third threshold of the motor rotation angle;
8. H. Reversing the motor rotation direction of the motor as a result of the second limit being exceeded by the motor Motor speed and the third limit by the motor rotation angle; and
9. i. Continue the procedure from point b ) as long as the user selection is active.

In this way, a simple and safe monitoring and control of the two parameters motor rotation direction and motor speed can be carried out, so that the rate of impact of the hammer in the forward direction results in a lower speed and a lower impact torque of the hammer on the anvil.

In one embodiment, the method includes automatic detection of the direction of engine rotation.

In a further embodiment, at least one first Hall sensor for measuring the motor rotation angle and at least one second Hall sensor for measuring the direction of motor rotation is used, whereby a simple measurement of the motor rotation angle and the motor rotation direction can be ensured.

In another embodiment, the engine speed, the engine acceleration, and the engine speed difference value are determined at each time based on the engine rotation direction and the engine rotation angle measurements.

In a further embodiment, in the steps d ) and G ) used as an additional criterion for reversing the direction of motor rotation, a current profile of the motor. In this way, the widest possible uniform and interference-free operation of the screwing is guaranteed without interruption.

Another object of the invention is a hand tool, in particular an impact wrench, comprising a housing with a motor, an output spindle, anvil, a hammer, a control unit, at least a first sensor and at least a second sensor. The motor rotates an input spindle, with the output spindle connected to a tool holder. The anvil is non-rotatably connected to the output spindle and the hammer is connected to the input spindle such that it intermittently moves in the axial direction of the input spindle and intermittently rotates about the input spindle due to rotational movement of the input spindle, the hammer thus intermittently strikes the anvil and thus gives a shock and an angular momentum to the anvil and thus to the output spindle. The first sensor transmits a first signal for determining a motor speed to the control unit, wherein the second sensor transmits a second signal for determining a motor rotation angle to the control unit. wherein the control unit is adapted to perform a method according to one of claims 1 to 5.

In a further embodiment, the at least one first sensor and the at least one second sensor are Hall sensors.

In another embodiment, during its intermittent movement, the hammer stores energy in a compression spring and releases that energy in the form of a hammering impact of the hammer on the anvil.

In a further embodiment, the traction tractor may comprise a switching element by means of which a user can select the method according to any one of claims 1 to 5 as operation of the traction tractor. Such a switching element has been found to be advantageous for easy handling of the power tool.

In another embodiment, the tractor-type traction machine is a battery-operated hand tool, in particular a battery-operated impact wrench. In this way, a flexible and network-independent use of the power tool is guaranteed.

In a preferred embodiment, the hand tool is a cordless screwdriver, a drill, a percussion drill or a hammer drill, which can be used as a tool a drill, a drill bit or various bit attachments. The hand-held traction machine according to the invention is designed in particular as impact wrench, wherein a higher peak torque for screwing or unscrewing a screw or a nut is generated by the impulsive release of the motor energy. In this context, transmission of electrical energy should be understood in particular to mean that the handheld power tool transmits energy to the body via a battery and / or via a power cable connection.

In addition, depending on the chosen embodiment, the screwing tool can be made flexible in the direction of rotation. In this way, the proposed method can be used both for screwing in and for unscrewing a screw or a nut.

Other features, applications and advantages of the invention will become apparent from the following description of the embodiment of the invention, which is shown in the drawing. It should be noted that the features described or illustrated in the figures, alone or in any combination, the subject matter of the invention, regardless of their combination in the claims or their dependency and regardless of their formulation or representation in the description or in the Drawing has only a descriptive character and is not intended to limit the invention in any way.

• 1 eine schematische Darstellung einer elektrischen Handwerkzeugmaschine; und
• 2 eine schematische Darstellung eines Programmablaufes zur Steuerung einer Handwerkzeugmaschine, insbesondere eines Schlagschraubers.

The invention will be explained in more detail below with reference to FIGS. Show it:

• 1 a schematic representation of an electric hand tool; and
• 2 a schematic representation of a program flow for controlling a power tool, in particular a impact wrench.

The 1 shows a hand tool according to the invention 100 that a housing 105 with a handle 115 having. According to the illustrated embodiment, the hand tool is 100 for mains-independent power supply mechanically and electrically with a battery pack 190 connectable. In 1 is the hand tool machine 100 exemplified as a cordless hammer drill. It should be noted, however, that the present invention is not limited to cordless drills, but rather handheld power tools 100 Application can be found in which a tool is rotated, for example, a cordless drill, a cordless impact drill or a rod screwdriver or a percussion drill etc.

In the case 105 are one of the battery pack 190 powered, electric drive motor 180 and a gearbox 170 arranged. The drive motor 180 is about the gearbox 170 with an input spindle 120 connected. The drive motor 180 is illustrative in a motor housing 185 arranged and the gearbox 170 in a gearbox 110 , where the gearbox 110 and the motor housing 185 merely as an example in the housing 105 are arranged. Furthermore, inside the housing 105 a control unit 370 arranged, which for controlling and / or regulating the drive motor 180 and the transmission 170 For example, by means of a set engine speed n, a selected angular momentum, a desired gear x or the like acts on them.

The drive motor 180 is for example via a handset 195 operable, ie, on and off, and may be any type of motor, such as an electronically commutated motor or a DC motor. This is the drive motor 180 such electronically controlled or regulated that both a reversing operation, as well as specifications with respect to the desired engine speed n and the desired angular momentum can be realized. The mode of operation and the design of a suitable drive motor are sufficiently known from the prior art, so that a detailed description of the description is omitted here for the purpose of conciseness of the description.

The input spindle 120 is rotatable in the housing 105 stored and via an output spindle 130 with a tool holder 140 Provided. The tool holder 140 serves to accommodate a tool 150 and can be connected to the output spindle 130 be formed or tower-connected with this.

The control unit 370 is connected to a power source. The control unit 370 is designed such that it the drive motor 180 electronically controllable or controllable by means of various current signals can control. The various current signals provide for different angular momentum of the drive motor 180 , wherein the current signals via a control line to the drive motor 180 be directed. The power source may be, for example, as a battery or, as in the illustrated embodiment as a battery pack 190 or be designed as a network connection.

Furthermore, not shown in detail controls may be provided to different operating modes and / or the direction of rotation of the drive motor 180 adjust.

2 shows a schematic diagram of a program sequence for controlling the rotational speed of the screwing the 1 ,

In a step a, a stop mode is started by a corresponding user selection. In one step b becomes a hand switch by an operator 195 operated, causing the drive motor 180 starts in a first direction of motor rotation. The first direction of motor rotation corresponds, for example, with a screwing in of a screw through the output spindle 130 , Depending on the selected mode of operation or on the selected embodiment, a predetermined actuation of the manual switch 195 be provided to start the energization of the drive motor 180 to effect.

At the step c and continuously forming a difference value of a motor speed between a first time and a subsequent second time. In step d, the difference value of the motor speed is then monitors whether it falls below a predetermined first limit, wherein the first limit represents the process of placing a screw head on a workpiece. If this is not the case, then it is time to move on b branches back. If the difference value of the engine speed falls below the specified first limit value, then the step goes to e branched.

In a step e, the motor rotation direction of the motor becomes low as a result of the first limit value of the difference value of the motor speed being undershot and the drive motor being operated 180 reverses in a second direction of motor rotation, wherein the second direction of motor rotation is reversed to the first direction of motor rotation. Basically, this means that an impact on the workpiece has been detected in the hammer. To avoid a hard impact of the hammer on the anvil, the hammer is stopped and the motor turns backwards.

In step f, the engine speed of the drive motor becomes 180 monitors whether the engine speed exceeds a specified second engine speed limit. In step G becomes a motor rotation angle of the drive motor 180 then monitors whether the motor rotation angle exceeds a predetermined third limit of the motor rotation angle.
If this is not the case, then it is time to move on e branches back. In this way it is ensured that, when the hammer moves sufficiently backwards and thus the difference value of the engine speed exceeds the specified second limit, in one step H the direction of motor rotation of the drive motor 180 is reversed as a result of exceeding the second limit by the engine speed and the third limit by the motor rotation angle.

In a following step i the procedure will start from step b as long as the user selection is active. The above procedure is repeated as long as the user uses the handset 195 actuated. In this way, a lower torque is achieved while reducing the rotational speed and thus allows better controllability and usability.

The invention is not limited to the described and illustrated embodiment. Rather, it also encompasses all expert developments within the scope of the invention defined by the claims.

In addition to the described and illustrated embodiments, further embodiments are conceivable which may include further modifications and combinations of features.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 2650085 A2 [0003]

Claims (10)

A method for controlling a hand tool (100), in particular an impact wrench, the impact wrench having a drive motor (180) with an input spindle (120) and a Ausgansspindel (130), wherein the drive motor (180), the input spindle (120) in rotation and the output spindle (130) is connected to a tool holder; furthermore, the impact wrench has an anvil rotatably connected to the output spindle (130) and a hammer, the hammer being connected to the input spindle (120) so as to intermittently move in the axial direction of the input spindle due to the rotation of the input spindle (120) (120) and performing an intermittent rotational movement about the input spindle (120); and wherein the hammer intermittently strikes the anvil thus delivering a beat and angular momentum to the anvil and thus to the output spindle (130); the method comprising the following steps: a. Start a stop mode by a corresponding user selection; b. Operating the drive motor (180) in a first direction of motor rotation, the first direction of motor rotation corresponding to threading a screw through the output spindle (130); c. Continuously forming a difference value of a motor speed between a first time and a subsequent second time; d. Monitoring the difference value of the motor speed as to whether it falls below a predetermined first limit value, the first limit value representing the process of placing a screw head on a workpiece; e. Reversing the engine rotational direction of the engine as a result of the first limit of the difference in engine speed being undershot and operating the drive motor (180) in a second engine rotational direction, the second engine rotational direction being inverse to the first engine rotational direction; f. Monitoring an engine speed of the drive motor (180) to determine whether the engine speed exceeds a predetermined second limit engine speed; G. Monitoring a motor rotation angle of the drive motor (180) to determine whether the motor rotation angle exceeds a predetermined third limit motor rotation angle; H. Reversing the motor rotation direction of the drive motor (180) as a result of exceeding the second limit by the motor speed and the third limit by the motor rotation angle; and i. Continue the procedure from step b as long as the user selection is active. Method according to Claim 1 , characterized in that the method comprises an automatic detection of the direction of motor rotation. Method according to one of Claims 1 or 2 , characterized in that at least a first Hall sensor for measuring the motor rotation angle and at least a second Hall sensor for measuring the direction of motor rotation is used. Method according to Claim 3 , characterized in that based on the measured values of the engine rotation direction and the motor rotation angle, the engine speed, the engine acceleration, and the difference value of the engine speed is determined at each time point. Method according to one of the preceding claims, characterized in that in steps d) and g) a current profile of the drive motor (180) is used as an additional criterion for reversing the direction of motor rotation. Hand tool (100), in particular an impact wrench, comprising a housing with a drive motor (180), wherein the drive motor (180) sets an input spindle (120) in rotation; an output spindle (130), the output spindle (130) being connected to a tool holder; an anvil, the anvil rotatably connected to the output spindle (130); a hammer, the hammer being connected to the input spindle (120) so as to perform an intermittent movement in the axial direction of the input spindle (120) and an intermittent rotational movement about the input spindle (120) due to the rotation of the input spindle (120); the hammer intermittently striking the anvil thus delivering a beat and angular momentum to the anvil and thus to the output spindle (130), a control unit (370), at least a first sensor, the first sensor providing a first signal for determining a motor speed to the control unit (370) transmits, at least one second sensor, wherein the second sensor transmits a second signal for determining a motor rotation angle to the control unit (370), characterized in that the control unit (370) for performing a method according to one of the Claims 1 to 5 is designed. Hand tool (100) according to Claim 6 , characterized in that the at least one first sensor and the at least one second sensor are Hall sensors. Hand tool (100) according to one of Claims 6 or 7 , characterized in that the hammer during its intermittent Movement stores energy in a compression spring and releases this energy in the form of a hammering impact of the hammer on the anvil. Hand tool (100) according to one of Claims 6 to 8th , characterized in that the hand tool (100) comprises a switching element, by means of which a user, the method according to one of Claims 1 to 5 as mode of operation of the power tool (100) can select. Hand tool (100) according to one of Claims 1 to 9 , characterized in that the hand tool (100) is a battery powered impact wrench.

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