EP3833510A1

EP3833510A1 - Hand-held machine tool and method for operating a hand-held machine tool

Info

Publication number: EP3833510A1
Application number: EP19742639.8A
Authority: EP
Inventors: Christian Iglhaut
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 2018-08-07
Filing date: 2019-07-30
Publication date: 2021-06-16
Anticipated expiration: 2039-07-30
Also published as: EP3833510B1; EP3608063A1; WO2020030468A1; US11597067B2; US20210316435A1

Abstract

The machine tool (1) of the invention comprises a tool holder (2), a motor (4) for driving the tool holder (2) such that the tool holder (2) rotates and/or performs percussions, and a magnetic field sensor (14) for sensing a magnetic field of the motor (4) generated as the tool holder is driven.

Description

Hand tool and method for operating a hand tool

FIELD OF THE INVENTION

The present invention relates to a handheld power tool and a method for operating a handheld power tool.

Handheld power tools often have load detection of an electric motor of the handheld power tool. For example, the handheld power tool can then be regulated according to a determined load. In conventional handheld power tools, the load is recognized by measuring the current in the electronics of the handheld power tool. The current measurement must be implemented in the power line. It is desirable to simplify and improve the load detection of an electric motor of the hand machine tool.

Against this background, the object of the present invention is to provide an improved hand-held machine tool and a method for operating one

Improve hand tool.

DISCLOSURE OF THE INVENTION

According to a first aspect, a handheld power tool is proposed. The

Handheld power tool comprises a tool holder and a motor for rotating and / or driving the tool holder. The handheld power tool also includes a magnetic field sensor for detecting a magnetic field of the motor that is generated by driving the tool holder.

The hand tool is, for example, a hammer drill, a chisel hammer, a combination hammer, a core drill or a screwdriver. The tool holder of the

Hand tool is used to insert a rotatable tool, e.g. B. a drill or a chisel tool. The motor of the hand power tool is in particular an electric motor, for example an electric motor with an adjustable speed. The motor of the hand-held power tool is used, in particular, to rotate the tool holder by rotating and / or driving the tool holder and / or to make a stroke movement. For example, the engine is used

Hand machine tool for rotating the tool holder around a working axis to set the tool in rotation about the working axis. By rotating the tool, an object, such as a surface and / or a wall, can be drilled. For example, the engine is used

Hand tool also to set the tool in a striking motion in the striking direction by driving the tool holder in a striking direction. The direction of impact is in particular parallel to the working axis. Through the

The movement of the tool can be chiseled.

The handheld power tool is set up, for example, in such a way that the tool holder does not start to drive until an object is machined.

For example, by actuating a main switch of the hand-held power tool, the motor of the hand-held power tool is put into operation, as a result of which the motor rotates, for example, at a specific motor speed. By putting the engine into operation, only the engine rotates, e.g. B. in the case of a chisel hammer, or it rotates the motor and the tool, e.g. B. in the case of a rotary hammer. By pressing the switched-on hand machine tool against the object to be machined, for example, the striking driving of the tool holder is started. By starting the striking driving of the tool holder, the tool executes striking movements in the case of the chisel hammer and executes rotational and striking movements in the case of the rotary hammer.

The magnetic field sensor of the hand machine tool is arranged in the vicinity of the motor. The magnetic field sensor is, for example, a Hall sensor, a magneto-resistive sensor or a field plate sensor. However, other magnetic field sensors can also be used in the

Hand machine tools are used. The magnetic field sensor detects the magnetic field of the motor created by driving the tool holder. In particular, the magnetic field sensor measures a magnetic field generated by a current-carrying conductor of the motor. This means that with the help of the magnetic field sensor, a current measurement of the motor can be carried out indirectly through the magnetic field measurement. In particular, by detecting the magnetic field of the motor, a current of the motor required to drive the tool holder is measured.

Due to the magnetic field sensor, a contactless and accurate current measurement of the hand machine tool, in particular the motor, can take place. In particular, due to the magnetic field sensor, a contactless and accurate load detection of the Hand machine tool, especially the motor. In particular, for load detection, it is not necessary to measure the current in the electronics of the

Implement hand tool.

The fact that a load detection of the hand tool by means of

Magnetic field sensor can be carried out contactlessly and accurately, different operating states of the handheld power tool can be recognized and / or differentiated from one another.

According to one embodiment, the magnetic field sensor is such in the

Handheld power tool arranged such that it detects, as the magnetic field of the motor, a magnetic field of a current which is absorbed by the motor when the tool holder is driven.

The magnetic field sensor is arranged in particular in the area of a power line of the motor. The power line of the motor is, in particular, a current-carrying conductor that connects a power supply to the hand tool, such as an accumulator or a power line, to the motor. By supplying power to the motor through the power line, the motor drives the tool holder to rotate and / or strike movements. A current flowing through the power line is particularly dependent on the power required to drive the tool holder. As a result, there is also one generated from the current flowing through the power line

Magnetic field depends on the power required to drive the tool holder. In particular, the current intensity of the current flowing through the power line is low when the handheld power tool is operated under low load at idle, and the current strength of the current flowing through the power line is high when the handheld power tool is machining a workpiece, that is to say is operated under load.

Because the magnetic field sensor is arranged in the hand-held power tool in such a way that, as the magnetic field of the motor, it detects the magnetic field of the current which is picked up by the motor when the tool holder is driven, an instantaneous current intensity required for driving the tool holder can be detected. This means that the current power consumption of the engine can be recorded.

According to a further embodiment, the hand tool has one

Control device for determining a load state of the motor as a function of the detected magnetic field. In particular, the control device receives the magnetic field of the motor detected by the magnetic field sensor as a signal. The control device determines a load state of the engine, for example by comparison with certain limit values. The load state of the motor depends in particular on a load applied to the hand tool. The load state of the engine is, for example, an idle mode and / or a low-load mode. In an idling mode, the engine in particular is the

Hand machine tool in operation, but no workpiece is machined. The load state of the engine can also be, for example, a load operation and / or a high load operation. In a load operation and / or high load operation, a workpiece is machined, in particular rotating and / or striking.

Because the hand-held power tool has a control device for determining the load state of the motor as a function of the detected magnetic field, different load states can be recognized during operation of the hand-held power tool and distinguished from one another. For example, the idle mode can be distinguished from the load mode. For example, the low-load operation can be distinguished from the high-load operation. For example, a pure drilling operation can be distinguished from a drilling and impact operation. For example, a

Idle operation can be distinguished from a field operation.

According to a further embodiment, the hand tool has one

Operating time counter for recording an operating time of the engine depending on the determined load state.

For example, the control device has the operating time counter. The operating time counter has, for example, a storage unit. The operating time counter is in particular set up to separately record and store the operating time of the engine for certain detected load states. For example, the operating time counter records the operating time of the engine in idle mode separately from the operating time of the engine in (high) load mode.

The fact that the hand-held power tool has the operating time counter for recording the operating time of the motor as a function of the determined load state can improve the recording of the motor operating time. According to a further embodiment, the control device is set up

Hand tool to set depending on the determined load state, in particular to control or regulate.

For example, the control device is set up, the hand tool in

Set the dependency of the determined load state in such a way that the engine speed of the engine is changed as a function of the determined load state. As a result, the speed of the motor can be adapted to the load condition and the energy efficiency of the motor can be improved.

Because the load state can be precisely recognized by means of the magnetic field sensor and the control device adjusts the handheld power tool depending on the load state determined, the handheld power tool can be adjusted very well, in particular controlled or regulated very well.

According to a second aspect, a method for operating a

Hand machine tool proposed. The hand tool has one

Tool holder and a motor for rotating and / or striking driving the tool holder. The method has a step of detecting a magnetic field of the motor resulting from the driving of the tool holder. The method also includes a step of determining a load condition of the engine in FIG

Dependence of the detected magnetic field.

Properties and advantages that have been described for the handheld power tool apply to the proposed method for operating the handheld power tool

corresponding.

According to an embodiment of the second aspect, the step of detecting the magnetic field of the motor comprises detecting a magnetic field of a current that is picked up by the motor when the tool holder is driven.

The magnetic field of the current that is picked up by the motor when the tool holder is driven is detected, for example, by detecting the magnetic field of the current that flows through the power line described in connection with the handheld power tool. According to a further embodiment of the second aspect, chiseling operation of the handheld power tool is recognized when the determined load state exceeds a certain limit value.

For example, the chiseling operation of the handheld power tool is recognized when the detected magnetic field and / or the current strength determined from the detected magnetic field exceeds the specific limit value. In particular, the control device compares the detected magnetic field and / or the current strength determined from the detected magnetic field with the determined limit value. The specific limit value is, for example, a specific magnetic field strength and / or a specific current strength. Because the chiseling operation of the hand tool can be detected with the aid of the magnetic field sensor, the hand tool can be set depending on whether chiseling operation is present or not.

According to a further embodiment of the second aspect, the method has a step of determining an operating time of the engine as a function of the determined load state.

The operating time of the motor is determined, for example, from the operating time counter described in connection with the handheld power tool.

According to a further embodiment of the second aspect, the determination of the load state of the motor as a function of the magnetic field detected distinguishes between idle operation of the handheld power tool and load operation.

As a result, the handheld power tool can be set depending on whether it is idling or under load.

According to a further embodiment of the second aspect, the

Handheld power tool a hammer drill and the determination of the load state of the motor in dependence on the detected magnetic field distinguishes a pure one

Drilling operations from a drilling and impact operation.

The hammer drill has in particular three different operating states. When the rotary hammer is idling, the motor and the drill rotate, but no workpiece is machined. In a pure drilling operation, the motor and the drill rotate and the drill processes a workpiece by rotating around the working axis. In In a drilling and hammering operation, the motor and the drill rotate and the drill processes a workpiece by a rotary movement about the working axis and one

Impact movement in the direction of impact.

In the hammer drill, the determination of the load state of the motor as a function of the magnetic field detected can have a distinction between the idle operation, the pure drilling operation and the drilling and impact operation. This means that the hammer drill can be set depending on whether it is idling, drilling-only or drilling and striking.

According to a further embodiment of the second aspect, the

Hand tool a chisel hammer and the determination of the load state of the motor as a function of the detected magnetic field distinguishes the idle operation from a striking operation.

The chisel hammer has in particular two different operating states. When the chisel hammer is idling, the motor turns, but no workpiece is machined. In the load state and / or impact mode of the chisel hammer, the motor rotates and the chisel tool processes a workpiece by means of an impact movement in the impact direction.

Due to the fact that with the chisel hammer the determination of the load state of the motor as a function of the detected magnetic field has a distinction between the idle mode and the impact mode, the handheld power tool can depend on whether the

Idle operation of the chisel hammer or impact operation is set.

According to a further embodiment of the second aspect, the method has a step of setting the handheld power tool as a function of the determined load state.

The setting is, for example, controlling the handheld power tool as a function of the determined load condition. Setting can also be a rule of the

Hand machine tool depending on the determined load state.

According to a further embodiment of the second aspect, the setting of the handheld power tool as a function of the determined load state comprises a change in an engine speed of the motor as a function of the determined load state. The control device has, for example, a processor and a computer program executed with the aid of the processor. The control device, for example that

Computer program, in particular comprises an algorithm or several algorithms, which is / are set up to determine a load state of the motor as a function of the detected magnetic field and / or to set the hand-held power tool as a function of the determined load state.

The respective unit, for example the processor, can be implemented in terms of hardware and / or also in terms of software. In a hardware implementation, the unit can be designed as a device or as part of a device, for example as a computer or as a microprocessor. In the case of a software implementation, the unit can be designed as a computer program product, as a function, as a routine, as part of a program code or as an executable object.

A computer program product, such as a computer program means, for example as a storage medium, e.g. Memory card, USB stick, CD-ROM, DVD, or in the form of a downloadable file from a server in a network. This can be done, for example, in a wireless communication network by transmitting a corresponding file with the computer program product or the computer program means.

The embodiments and features described for the method apply accordingly to the handheld power tool and vice versa.

BRIEF DESCRIPTION OF THE FIGURES

The following description explains the invention using exemplary

Embodiments and figures. The figures show:

Fig. 1 is a schematic view of a hand machine tool; and

Fig. 2 is a schematic view of a method for operating the

Hand tool according to FIG. 1.

EMBODIMENTS OF THE INVENTION An embodiment of handheld power tool 1 and a method for operating handheld power tool 1 are described below with reference to FIGS. 1 and 2.

1 shows a hammer drill as an exemplary embodiment of handheld power tool 1. The hammer drill 1 has a tool holder 2, in which a shaft end of a tool 3, for. B. a drill can be used. A motor 4, which drives a striking mechanism 5 and a drive shaft 6, forms a primary drive of the hammer drill 1. On

Accumulator 7 or a power line (not shown) supplies motor 4 via a

Power line 17 with electricity. In the example shown in FIG. 1, the accumulator 7 supplies the motor 4 with current and is connected to the motor 4 through the power line 17.

A user can hold and guide the hammer drill 1 by a handle e. The handle 8 is part of a housing 9 of the rotary hammer 1. The rotary hammer 1 can be put into operation by means of a main button 10. By pressing the main button 10, the motor 4 is supplied with current from the accumulator 7 via the power line 17. The motor 4 drives the drive shaft 6 by supplying current. The one with the

Tool holder 2 coupled drive shaft 6 sets the tool holder 2 in a rotary movement about a working axis 1 1. This turns the tool 3 around the

Working axis 1 1 rotated. During operation, the rotary hammer 1 can use the tool 3 in addition to rotation about the working axis 11 in a direction of impact 12 along the

Hammer working axis 1 1 into a subsurface. For example, the hammer drill 1 is set up such that the striking movement of the tool 3 only begins when an object is being machined. For example, by pressing the activated rotary hammer 1 against the object to be machined, a drive starts

Tool holder 2 by the striking mechanism 5. As a result of the striking mechanism 5 driving the tool holder 2, the tool 3 performs 1 striking movements in the striking direction 12 in addition to the rotary movement about the working axis 11. In one

The drill hammer 1 has an operating mode selector switch 13, by means of which the tool holder 2 can be decoupled from the drive shaft 6, so that the hammer drill 1 can be operated purely by chiseling.

FIG. 2 shows a schematic view of a method for operating the rotary hammer 1 from FIG. 1.

In a first step S1 of the method, a by driving the

Tool holder 2 generated magnetic field of the motor 4 detected. For this purpose, the hammer drill 1 has, next to the motor 4, in particular adjacent to the power line 17, a magnetic field sensor 14 for load detection of the motor 4, as can be seen in FIG. 1. The current required for rotating and / or driving the tool holder 2 flows through the power line 17 to the motor 4 and generates one

Magnetic field around the power line 17. The magnetic field sensor 14 detects the magnetic field of the motor 4, in particular the power line 17.

In a second step S2 of the method, a load state of the engine 4 in

Dependence of the detected magnetic field determined.

The strength of the current flowing through the power line 17 depends on the current power consumption of the motor 4 of the hammer drill 1. Thus, the strength of the magnetic field generated by the current flowing through the power line 17 also depends on the instantaneous power consumption of the motor 4 of the hammer drill 1.

By actuating the main button 10, the motor 4 is rotated. As long as the tool 3 has not yet machined the workpiece, that is to say that the rotary hammer 1 is idling, the load on the motor 4 is low and the

Power consumption of the motor 4 is correspondingly low. In this state, a current with a low current intensity flows through the current conductor 17, which generates a weak magnetic money around the current conductor 17. If a workpiece is now machined with the tool 3, the load on the motor 4 and the power consumed by the motor 4 increase in comparison to the idle mode. If in a pure

Drilling operation of the hammer drill 1, the workpiece is machined with the tool 3, the current strength of the current flowing through the current conductor 17 and the strength of the magnetic field generated by the current around the current conductor 17 increases 4 applied load still further. In such a drilling and striking operation of the hammer drill 1, the load of the motor is correspondingly large and a current flows through the current with a large current

Current conductor 17. This creates a strong magnetic money around the current conductor 17.

By detecting the magnetic field around the current conductor 17 in the first step S1 of the method, these different load states can be determined and distinguished by a control device 15 of the rotary hammer 1 in the second step S2 of the method. In particular, the magnetic field sensor 14 transmits the detected magnetic field as a signal to the control device 15. The control device 15 compares the detected Magnetic field with certain limit values and thus determines whether there is an idle operation, a pure drilling operation or a drilling and striking operation. The certain limit values are certain values for the magnetic field strength. For example, the control device 15 determines that there is an idling operation when the detected magnetic field is less than a first limit value. For example, the control device 15 determines that there is a pure drilling operation if the detected magnetic field is greater than or equal to the first limit value and less than a second limit value. For example, the control device 15 determines that there is a drilling and striking operation if the detected magnetic field is greater than or equal to the second limit value.

In a third step S3 of the method, an operating time of the engine 4 in

Dependency of the determined load state determined.

For this purpose, the hammer drill 1, in particular the control device 15, can have, for example, an operating time counter 16 for recording the operating time of the engine 4 as a function of the determined load state, as can be seen in FIG. 1. The control device 15 and / or the operating time counter 16 have, for example, a storage unit (not shown) for storing the recorded operating time as a function of the determined one

Load state. The operating time counter 16 records, for example, when the

Skin button 10 continuously or in narrow time intervals the operating time of the engine 4 and assigns it to the load state determined by the control device 15. For example, after switching on the rotary hammer 1 via the main button 10, the operating time counter 16 first records an operating time in idle mode, followed by an operating time in drilling and hammering operation.

In a fourth step S4 of the method, the rotary hammer 1 is set, in particular controlled, as a function of the determined load condition. For example, the

Engine speed of engine 4 changed depending on the determined load condition.

For example, the engine speed is reduced in the idling mode and becomes the

Engine speed increased in the impact and drilling operation. By adapting the

Engine speed to the load state of the hammer drill 1, the energy consumption of the hammer drill 1 can be reduced. LIST OF REFERENCE NUMBERS

1 hand tool (hammer drill)

2 tool holder

3 tools

4 engine

5 striking mechanism

6 drive shaft

7 accumulator

8 handle

9 housing

10 main buttons

1 1 working axis

12 direction of impact

13 mode selector switch

14 magnetic field sensor

15 control device

16 operating time counters

17 power line

51 procedural step

52 procedural step

53 procedural step

54 procedural step

Claims

1. Hand tool (1) with

a tool holder (2),

a motor (4) for rotating and / or driving the

Tool holder (2), and

a magnetic field sensor (14) for detecting a by driving the

Tool holder of the generated magnetic field of the motor (4), the magnetic field sensor (14) being arranged in the hand tool (1) in such a way that as the magnetic field of the motor (4) it detects a magnetic field of a current which is generated when the

Tool holder is received by the motor (4), characterized in that a control device (15) for determining a load state of the motor (4) in dependence on the detected magnetic field for distinguishing an idle operation of the hand tool (1) from a load operation.

2. Hand tool (1) according to claim 1, characterized in that it has an operating time counter (16) for detecting an operating time of the motor (4) as a function of the determined load state.

3. Hand tool (1) according to claim 1 or 2, characterized in that the control device (15) is set up to set the hand tool (1) as a function of the determined load condition.

4. A method for operating a hand tool (1), which a

Tool holder (2) and a motor (4) for rotating and / or striking

Drive the tool holder (2), with the steps:

Detecting (S1) a magnetic field of the motor (4) resulting from driving the tool holder (2), and

Determining (S2) a load state of the motor (4) as a function of the magnetic field detected,

characterized in that the determination (S2) of the load state of the motor (4) as a function of the detected magnetic field has a distinction between an idle operation of the hand tool (1) and a load operation.

5. The method according to claim 4, characterized in that the detection (S1) of the magnetic field of the motor (4) comprises a detection of a magnetic field of a current which is received by the motor (4) when driving the tool holder (2).

6. The method according to claim 4 or 5, characterized in that a chiseling operation of the hand tool (1) is detected when the determined load state exceeds a certain limit.

7. The method according to any one of claims 4 to 6, characterized by a step:

Determining (S3) an operating time of the engine (4) as a function of the determined load state.

8. The method according to any one of claims 4 to 7, characterized in that the determination (S2) of the load state of the motor (4) in dependence on the detected magnetic field has a distinction between an idle operation of the hand tool (1) from a load operation.

9. The method according to any one of claims 6 to 10, characterized in that the handheld power tool (1) is a hammer drill and determining (S2) the load state of the motor (4) as a function of the magnetic field detected distinguishing a pure drilling operation from a drilling and striking operation.

10. The method according to claim 8, characterized in that the hand tool (1) is a chisel hammer and the determination (S2) of the load state of the motor (4) in

Dependency of the detected magnetic field has a distinction between the idle mode and an impact mode.

1 1. The method according to any one of claims 4 to 9, characterized by a step:

Setting (S4) the hand tool (1) depending on the determined load condition.

12. The method according to claim 11, characterized in that the setting (S4) of the hand tool (1) in dependence on the determined load condition comprises a change in an engine speed of the motor (4) in dependence on the load condition determined.