EP4143971A1

EP4143971A1 - Hand-held machine tool

Info

Publication number: EP4143971A1
Application number: EP21718909.1A
Authority: EP
Inventors: Christian Koschel; Christian Ruff; Stefan Schwarz; Georg Fürfanger
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 2020-04-29
Filing date: 2021-04-20
Publication date: 2023-03-08
Also published as: EP3905527A1; CN115413398A; US20230238957A1; WO2021219440A1

Abstract

The invention relates to a hand-held machine tool (1) comprising a housing (2), a drive device for actuating a tool that can be operatively connected to the machine tool (1), and a control device (8) for actuating the drive device (4); the control device (4) includes a control element (10), and at least one capacitive sensor element (32, 33) is operatively connected to the control device (10). The at least one sensor element (32, 33) and/or the control element (10) is/are separated in at least some areas, in particular nearly entirely, from a main duct (50) of the machine tool (1) in which the drive device (4) is arranged.

Description

Hand-held machine tool

The invention relates to a hand-held machine tool with a housing, wherein a drive device for actuating a tool that can be brought into operative connection with the machine tool and a control device for actuating the drive device is provided, according to the type defined in more detail in the preamble of claim 1.

Hand-held machine tools that are designed with a capacitive sensor are known from practice. By means of the capacitive sensor, for example, a power switch can be released and then a drive device can be actuated via a switch that can be actuated by the user. A so-called dead man function can be provided by means of the capacitive sensor. The capacitive sensor is arranged, for example, in a grip area of the machine tool and can detect a hand of a user located in the grip area.

However, the determination of the presence of a user's hand is subject to interfering influences that can lead to incorrect detection. In hand-held machine tools, it is usually provided for example to ensure a desired operation of the machine tool to cool a drive device. Here, a cooling device, for example a fan, is provided, by means of which a flow of cooling air is guided in a main channel provided in a housing of the machine tool to the components to be cooled, in particular the drive device. Dirt, for example conductive particles, and moisture can be transported by the cooling air flow when the machine tool is in operation. This dirt and moisture can lead to incorrect detection by the capacitive sensor.

It is therefore the object of the present invention to provide a hand-held machine tool with which the risk of incorrect detection can be reduced. It is therefore proposed a hand-held machine tool with a housing, a drive device for actuating a tool that can be brought into operative connection with the machine tool and a control device for actuating the drive device is provided, the control device being designed with a control element, and at least one with the control device operatively connected, capacitive sensor element is provided.

According to the invention, it is proposed that the at least one sensor element and / or the control element be at least partially, in particular almost completely separated from a main channel of the machine tool in which the drive device is arranged.

By separating the at least one sensor element and / or the control element from the main channel, the at least one sensor element and / or the control element can be effectively separated or encapsulated from interfering influences present in the area of the main channel. In particular, the at least one sensor element and the control element are thereby protected from moisture and dirt and, in particular, electrically conductive materials such as grinding dust, which are transported in the main channel, for example, by the provision of a fan. The risk of incorrect detection of the at least one sensor element due to the conditions present in the main channel is thereby greatly reduced in a simple manner.

The main channel is arranged in particular in a grip area of the machine tool, with cooling air preferably being passed through the main channel to cool the drive device. In particular, the main channel has a cross section that is many times larger than an area in which the at least one control element and / or the at least one sensor element is arranged.

The cooling air is guided in the direction of the drive device, for example, from an end region of the machine tool in which, for example, at least part of the control device and / or an accumulator of the machine tool is arranged. A handle area of the machine tool is preferably provided essentially between the end area of the machine tool and the area of the machine tool in which the drive device is arranged.

The control element is designed, for example, as a printed circuit board and preferably has a signal transmitter and a control unit. The control element is particular Connected via lines to a main control unit of the control device and can thereby be arranged at a distance from the main control unit.

The presence of a hand of a user in an area in which the sensor element is arranged, for example in the grip area, can be determined by means of the sensor element and the control device. This can be determined by the fact that the sensor element can absorb a greater electrical charge when charged with a constant voltage by the hand. It can be provided, for example, that the sensor element is alternately charged and discharged and, when a defined threshold value for the determined electrical charge is exceeded, the presence of a hand is assumed.

In the present case, the main channel is understood to mean the channel of the machine tool in which, in particular, the drive device is arranged, with cooling air preferably being passed passively or actively through the main channel.

The hand-held machine tool can be all types of hand-held machine tools, such as grinding machines, for example Winkelschlei fer, sawing machines, such as reciprocating saws, jigsaws, circular saws or chainsaws, drilling machines, Meissei hammer or the like.

In an advantageous embodiment of a hand-held machine tool according to the invention, in which the influence of interfering influences present in an interior of the machine tool is particularly effectively reduced, the at least one sensor element and / or the control element can be arranged in an area completely separated from the main channel be. This ensures that a cooling air flow, for example guided through the main channel, does not come into contact with the at least one sensor element and / or the control element, so that the risk of malfunctions can be greatly reduced. The at least one sensor element and / or the control element is preferably at least partially, in particular essentially completely airtight, separated from the main channel, with sealing elements being able to be provided to achieve the separation.

In order to achieve an at least regional separation of the at least one sensor element from the main channel in a structurally simple manner, the at least one sensor element can be arranged in a channel. The channel is preferably arranged at least in some areas in an area of the housing close to the surface, so that an inlet interaction of the at least one sensor element, for example with one hand of a user, is possible simply and safely.

In an advantageous embodiment of the invention, several sensor elements are provided, each sensor element being arranged at least in some areas in a separate duct or space, which is at least in some areas, in particular essentially completely separated from the main duct. In this way, interactions between the individual sensor elements can also be reliably prevented.

In an embodiment that is economical in terms of installation space, provision can also be made for at least two sensor elements to be arranged jointly, at least in some areas, in a channel.

In a structurally simple implementation of a sensor element, this is implemented as a line, the line extending in particular from the control element to a detection area of the sensor element, for example a grip area of the machine tool. The line is preferably made of copper.

For the effective separation of the control element from the main channel, the control element can be arranged in a chamber which is at least partially, in particular essentially, completely separate from the main channel. It can be provided that the control element and the at least one sensor element are jointly separated from the main channel. As an alternative to this, it can also be provided that the control element and the at least one sensor element are at least partially separated from the main channel.

In a structurally simple implementation of the solution according to the invention, it can be provided that the housing is designed in at least two parts, at least one channel and / or the chamber being formed jointly at least in some areas by at least two parts of the housing. A machine tool designed in this way is easy to assemble.

The at least one sensor element and the control element are preferably part of a capacitive measuring sensor. The control element preferably has a control unit and a signal generator, the signal generator being designed in particular to charge the sensor elements, which are designed, for example, as lines, with a defined voltage. The control unit is preferably designed to detect changes in charge in the at least one sensor element, for example se the presence of a hand is detected if the determined charge is greater than a defined threshold value. Such changes in the determined charge occur, for example, when a user's hand is in a defined area of the machine tool, since this increases the overall capacity. The control element then sends in particular a signal to the control device, which then preferably enables operation of the machine tool in the event of a user request. To determine the actually existing electrical charge of a sensor element, a capacitor which has a small capacitance compared to a capacitance of the sensor element can be provided, which is fully charged with the electrical charge of the sensor element and then discharged and the number of processes is counted. until the relevant sensor element is completely discharged. If a defined threshold value for the number of these processes is exceeded, this can be interpreted as the presence of a hand.

In an advantageous embodiment of a machine tool according to the invention, a circuit breaker operatively connected to the control device and operable by the user can be provided, the control device being designed to transfer the circuit breaker between an inactive state and an active state, with the user operating the circuit breaker in the active state of the Circuit breaker leads to actuation of the drive device. By means of the control device, the line switch can be operated in such a way that a user-side actuation of an actuating element that is operatively connected to the circuit breaker for coupling the drive device to power, for example from an accumulator or from a power network, and thereby actuates the drive device. It can be achieved in a simple manner that the machine tool can only be actuated when a hand located, for example, in the grip area can be detected by means of the control device in cooperation with the at least one capacitive sensor element and / or the control element. It can also be provided that the circuit breaker which is in the active state is switched to the inactive state if the control device in cooperation with the at least one capacitive sensor element and / or the control element does not detect a hand in the grip area . A so-called dead man function can thus be implemented in a simple manner. In the active state, the circuit breaker is designed to lead a motor current to the drive device, as a result of which the tool can be actuated.

Further advantages emerge from the following description of the figures. An exemplary embodiment of the present invention is shown in the figures. The characters, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.

Show it:

1 shows a greatly simplified longitudinal sectional view of a hand-held machine tool designed as an angle grinder, a tool being arranged on an output shaft of the angle grinder;

FIG. 2 shows a longitudinal sectional view of the angle grinder according to FIG. 1;

3 shows a further longitudinal sectional view of the angle grinder according to FIGS. 1 and 2;

4 shows a side view of the angle grinder according to FIGS. 1 to 3;

5 shows a cross-sectional view of the angle grinder according to FIGS. 1 to 4 along the line A - A in FIG. 4;

6 shows a simplified cross-sectional view of the angle grinder according to FIGS. 1 to 5 along the line A - A in FIG. 5;

7 shows a simplified three-dimensional view of the angle grinder according to FIGS. 1 to 6 without part of a housing, an additional handle being shown;

8 shows a schematic view of a working principle of a sensor element; and

9 shows a simplified three-dimensional view of a section of the angle grinder according to FIGS. 1 to 8, wherein a shielded sensor element can be seen in more detail;

10 shows an exemplary sequence of a method for actuating the angle grinder according to FIGS. 1 to 9.

In Fig. 1 to Fig. 7 and Fig. 9, a hand-held machine tool 1 according to the invention is shown, which is designed as an angle grinder in the representation shown. According to an alternative embodiment, the machine tool 1 can also be used as a drilling machine ne, be designed as a hammer drill, a sawing machine, a Meissei hammer or the like.

The machine tool 1, embodied as an angle grinder in the figures, has a housing 2 and a tool 3, embodied, for example, as a cutting disk or grinding disk and releasably connectable to an output shaft 7 of the machine tool 1. The tool 3 can be actuated by a drive, in particular designed as an electric motor, or a drive device 4, which can be supplied with power in particular via an accumulator 5 that can be connected to the machine tool 1. The accumulator 5, like the housing 2, is not shown in all of the figures.

According to an alternative embodiment not shown in the figures, the machine tool 1 can also be supplied with electrical power from a network via a power cable.

The drive device 4 for actuating the tool 3 here in a rotating motion is, like a gear 6, arranged in an interior of the housing 2. The drive 4, which is designed as an electric motor, for example, the transmission 6 and the output shaft 7, with which the tool 3 can be effectively connected, are arranged and connected to one another in such a way that a torque generated by the electric motor 4 is applied to the transmission 6 and finally to the Output shaft 7 can be transmitted. A freely rotating end of the output shaft 7 protruding downward on the housing 2 is connected to the tool, which is designed here as a cutting disk 3, for example via a clamping device which is not shown in detail. The torque of the output shaft 7 is thus transmitted directly to the cutting disk 3.

A protective device designed as a protective hood 12 is provided, which is preferably releasably connectable to the housing 2 of the machine tool 1 in a conventionally known manner and can be provided to protect a user when the machine tool 1 is in operation.

The housing 2 has at least one holding area 22 or grip area, which is provided for holding and guiding the machine tool 1 by one or both hands of a user. The holding area 22 is assigned a switch 20 which can be actuated by a user when the machine tool 1 is held in the grip area 22. As an alternative or in addition to this, the machine tool 1 can have a further handle device 26 which, for example, can be releasably connected to the housing 2 of the machine tool 1 in a head region 24 of the machine tool 1 facing the tool 3 and, for example, provides a different working position for the user represents. Fig. 7 shows an additional handle 26 of this type, which can be detachably connected to the housing 2 in the region of a connection point 28.

The machine tool 1 also has a control device 8, which is designed here with main control electronics 9 and a control element 10. The control element 10 is preferably designed as a printed circuit board and is electrically and electronically connected to the main control electronics 9, which are arranged in the area of the accumulator 5 in the present case.

A power switch 21 which can be operated by the user by means of the switch 20 is in turn connected to the main control electronics 9. The circuit breaker 21 designed as a MOSFET, for example, is provided for releasing a current from the accumulator 5 to the electric motor 4.

The machine tool 1 is designed in the present case with a so-called dead man function. For this purpose, the circuit breaker 21 of the control device 8 is between an active state in which a user-side actuation of the switch 20 leads to an actuation of the electric motor 4 and an inactive state in which a user-side actuation of the switch 20 does not lead to an actuation of the electric motor, transferable. To transfer the circuit breaker 21 between the active state and the inactive state, the control element 10 is carried out in the manner explained in more detail below.

In the present case, the control element 10 is operatively connected to a plurality of sensor elements 30, 31, 32, 33, 34, 35, four of which can be seen in FIG. 1. The sensor elements 30, 31, 32, 33, 34, 35 are each designed here with a line or designed as a line. The present sensor elements 30, 31, 32, 33, 34, 35, which interact with one another only via the control element 10, are essentially designed to be comparable here, but extend from the control element 10 into different areas of the machine tool 1.

The control element 10 has, in particular, a control unit and a signal generator, the signal generator being designed in particular to be equipped with lines. led sensor elements 30, 31, 32, 33, 34, 35 to charge with a defined voltage.

The control unit is preferably designed to detect changes in charge in the at least one sensor element, for example the presence of a hand being detected when the charge determined is greater than a defined threshold value.

In the following, a vertical direction H, a longitudinal direction L and a transverse direction Q are used for a more detailed description of the machine tool 1. In the present exemplary embodiment, the longitudinal direction L relates to a direction between the accumulator 5 and the head region 2. The vertical direction H here essentially corresponds to an extension direction of the output shaft 7 and the transverse direction is essentially perpendicular to the longitudinal direction L and the vertical direction H and represents Essentially represents the direction of extension of the handle device 26.

A first sensor element 30, starting from the control element 10, initially runs essentially in the vertical direction H upwards and from a region near the surface in the longitudinal direction L in the direction of the head region 24 forwards. The first sensor element 30 is arranged in its region running essentially in the longitudinal direction L within the housing 2 in a proximity to the surface of the housing 2 and runs essentially in the holding region 22. The first sensor element 30 extends in the longitudinal direction L essentially up to a Area in which the electric motor 4 is arranged.

A second sensor element 31, starting from the control element 10, initially runs essentially in the vertical direction H downwards and from a region near the surface in the longitudinal direction L in the direction of the head region 24 forwards. The second sensor element 31 is arranged in its area running essentially in the longitudinal direction L within the housing 2, in turn in a proximity to the surface of the housing 2 and runs essentially in the holding area 22. The second sensor element 31 essentially extends in the longitudinal direction L up to an area in which the electric motor 4 is arranged.

A third sensor element 32, starting from the control element 10, initially runs essentially in the vertical direction H upwards and from a region near the surface in the longitudinal direction L in the direction of the foot region 25 to the rear. The third sensor element 32 is arranged in its region running essentially in the longitudinal direction L within the housing 2 in a proximity to the surface of the housing 2 and runs essentially in the holding region 22. The third sensor element 32 extends in Longitudinal direction L essentially up to an area in which the accumulator 5 is arranged. The third sensor element 32 can also, as can be seen in FIGS. 3 and 4, extend into a foot region 25 of the machine tool 1 in which the accumulator 5 is arranged.

A fourth sensor element 32, starting from the control element 10, initially runs essentially in the vertical direction H downwards and from a region near the surface in the longitudinal direction L in the direction of the foot region 25 to the rear. The fourth sensor element 33 is arranged in its area running essentially in the longitudinal direction L within the housing 2 in a proximity to the surface of the housing 2 and essentially runs in the holding area 22. The fourth sensor element 32 extends in the longitudinal direction L essentially to in an area in which the accumulator 5 is arranged. The fourth sensor element 33 can also, as can be seen in FIGS. 3 and 4, extend into the foot region 25 of the machine tool 1.

The first sensor element 30 and the third sensor element 32 are thus arranged in an area of the housing 2 that is upper with respect to the vertical direction H and the second sensor element 31 and the fourth sensor element 33 are arranged in an area of the housing 2 that is lower with respect to the vertical direction H.

In FIG. 7, a fifth sensor element 34 and a sixth sensor element 35 are shown in a greatly simplified manner, these likewise being connected to the control element 10 in a manner comparable to the sensor elements 30, 31, 32, 33. The fifth sensor element 35 extends from the control element 10 to the handle device 26 and in particular within the handle device 26 further to a handle area 27 of the handle device 26. It can be provided that the fifth sensor element 34 is designed in two parts, with a first part 37 , which runs within the housing 2 and a second part 38 which runs inside the handle device 26. A connection device 28 for connecting the handle device 26 to the housing 2 is designed such that when the handle device 26 is connected to the housing 2, the first part 37 of the fifth sensor element 34 is operatively connected to the second part 38 of the fifth sensor element 34.

The sixth sensor element 35, also visible in FIG. 7, extends from the control element 10 to the protective device 12, with a course of the sixth sensor element 35 within the housing 2 basically arbitrarily selectable depending on the available space conditions. The sixth sensor element 35 can preferably be used to determine whether the protective device 12 is connected to the housing 2 and, in particular, whether the protective device 12 is connected to the housing 2 in the intended manner, that is to say correctly.

In an alternative embodiment, it can also be provided that only any combination of the sensor elements 30, 31, 32, 33, 34, 35 is provided. As an alternative to this, further sensor elements can also be provided, wherein, for example, sensor elements can also be arranged in an area of the housing 2 which is lateral with respect to the transverse direction Q.

In the present case, the sensor elements 30, 31, 32, 33, 34, 35 are all designed as capacitive sensor elements, whereby a change in charge in the respective sensor element 30, 31, 32, 33, 34, 35 can be determined in conjunction with the control element 10. To determine a change in charge, it can be provided that the respective sensor element 30, 31,

32, 33, 34, 35 is charged by the control device 8 or the control element 10 up to a defined voltage and the respective sensor element 30, 31, 32, 33, 34,

35 is then discharged. It can be provided that, for example, the control element 10 is assigned a capacitor which has a small capacitance comparable to the typical charging of a sensor element 30, 31, 32, 33, 34, 35 and how often this is determined by the respective Sensor element 30, 31, 32, 33, 34, 35 can be loaded until the respective sensor element 30, 31, 32, 33, 34, 35 is completely discharged.

The charge that the respective sensor element 30, 31, 32, 33, 34, 35 can absorb is essentially constant. A human hand has a capacitance which is added to the capacitance of the sensor element 30, 31, 32, 33, 34, 35 when the human hand is in the vicinity of the respective sensor element 30, 31, 32, 33, 34, 35 comes. Since the respective sensor element 30, 31, 32, 33, 34, 35 is charged to a constant voltage, the charge absorbed by the sensor element 30, 31, 32, 33, 34, 35 increases, for example in the presence of a hand , so that when the respective sensor element 30, 31, 32, 33, 34, 35 is discharged, a greater amount of charge is present than when there is no human hand.

In particular, the sensor elements 34 and 35 can be designed in such a way that the respectively assigned defined threshold value is exceeded when the handle device 26 or the protective device 12 is arranged in the desired manner on the housing 2 and the respective defined threshold value is not exceeded, for example, when no handles direction 26 or no protective device 12 is mounted or this is not mounted on the housing 2 in the desired manner.

Each sensor element 30, 31, 32, 33, 34, 35 is assigned a defined threshold value for the determined electrical charge, the exceeding of the respective threshold value being interpreted as the presence of a hand or the presence of the handle device 26 or the protective device 12.

It can be provided that the control element 10 transfers the circuit breaker 21 from the inactive state to the active state when at least one determined electrical charge of a sensor element 30, 31, 32, 33, 34, 35 or several determined electrical charges from different sensor elements 30, 31, 32, 33, 34, 35 exceeds the respective assigned threshold. Thus, a prerequisite for transferring the circuit breaker 21 from the inactive state to the active state can be that the charge determined by the fifth sensor element 34 exceeds the corresponding threshold value and / or the charge determined by the sixth sensor element 36 exceeds the corresponding threshold value and thus the presence of the handle device 26 and / or the protective device 12 for activating the circuit breaker 21 is required.

The circuit breaker 21 is actually transferred from the inactive state to the active state, for example, only if, in addition to the above-mentioned requirement, there is a predefined condition for the sensor elements 30, 31, 32, 33 and, for example, the determined electrical charge of one or more of these Sensor elements 30, 31, 32, 33 exceed the respectively assigned defined threshold value.

It can be determined, for example, whether the machine tool 1 is being held by a user in the desired manner. This can be determined in that the determined charges of defined sensor elements which are arranged in corresponding areas of the machine tool 1 exceed the respectively assigned threshold value and / or the determined charges of other defined sensor elements which are arranged in corresponding areas of the machine tool 1 , do not exceed the assigned threshold value. It can thus be determined, for example, whether the machine tool is being held in the holding area 22 and in the grip area 27 and, for example, the circuit breaker 21 is only switched to the active state in this case. As an alternative or in addition to this, it can be provided that the circuit breaker 21 is not switched to the active state when a determined charge of a defined sensor element, which is arranged, for example, in a certain area, for example in an area located close to the tool 3 , exceeds the assigned threshold value.

In addition, by appropriately positioning the sensor elements 30, 31, 32, 33, 34, 35, different grip positions of a user can be determined depending on the determined charges of the respective sensor elements 30, 31, 32, 33, 34, 35 and the drive device 4 can be operated in different operating modes depending on the determined grip position. This can be provided, for example, in a machine tool 1 designed as an angle grinder using a tool 3 designed as a cutting disk or as a grinding wheel, in which the machine tool 1 is held differently and the use of the various tools 3 have different optimal speeds.

As an alternative or in addition to this, it can also be provided that the circuit breaker 21 is only transferred from the inactive state to the active state if the electrical charge determined by a sensor element 30, 31, 32, 33, 34, 35 is less than the respective one defined threshold. This can be provided in particular to prevent a hand of a user from being in a defined area of the machine tool 1, for example. A region in which a user is not allowed to have a hand to operate the machine tool 1 can be provided as a defined region, for example. As an alternative or in addition to this, the defined area can be a danger area which is located in particular in the vicinity of the tool 3. The corresponding sensor elements 30, 31, 32, 33, 34, 35 can be arranged in the desired areas of the machine tool 1 in addition to the embodiment shown.

It can also be provided that the circuit breaker 21 is transferred from the active state back to the inactive state if the electrical charge determined by a sensor element 30, 31, 32, 33, 34, 35 falls below the respectively defined threshold value, as this for example, to a removal of a hand from the holding area 22 or the grip area 27 or to a removal of the protective device 12 and / or the grip device 12 and thus an undesirable operating state.

The fifth sensor element 34 can be provided to determine only the presence of the handle device 26. As an alternative or in addition to this, it can also be provided be that the presence of a hand of a user in the grip area 27 can also be determined by means of the fifth sensor element 34.

In order to reliably prevent, for example, a hand that is in an area deviating from the intended detection area, for example in an area outside the grip area 27, from undesirably exceeding the assigned defined threshold value, it can be provided that the defined threshold value is exceeded the area of the fifth sensor element 35 facing away from the detection area is shielded and, for example, the presence of a user's hand in this area does not lead to the associated defined threshold value of the fifth sensor element 34 being exceeded.

In Fig. 9 a section of the hand-held machine tool 1 or the Winkelschlei fers can be seen in more detail, wherein the at least partially, in particular completely with a metallic housing 70 designed head region 24 of the angle grinder 1 is not shown. It is a rear part 71 of the housing 2 can be seen, the multiple connection points 72, 73 for connecting the rear part 71 of the housing 2 with the metallic's housing 70, two of which can be seen here.

In order to protect the fifth sensor element 34 in areas not intended for detection, for example in the area running in the rear housing 71, from interference, undesired detections or incorrect detections, for example by the drive device 4, the part running in the area of the rear housing 71 is necessary of the fifth sensor element 34 in the present case is comprised by a further element 75. The further element 75 is designed here as a line 75, which in the present case encompasses or encloses the line of the fifth sensor element 34 in a spiral shape.

In the present case, the line 75 is connected to a negative pole of the accumulator 5 for grounding. As an alternative to this, it can also be provided that the line 75 is connected to a further sensor input.

In the case of mains-operated machine tools, the line for grounding can be connected to a neutral, grounded conductor. If an AC-to-DC converter is provided, the ground line 75 can also be connected to the negative pole of the DC circuit.

The fifth sensor element 34, which is designed to be as thin as possible to reduce parasitic capacitance effects, is in the area of the connection point 72 with a electrically conductive element 77 which, when the rear housing part 71 is connected to the metallic housing 70, is conductively connected to a further area of the fifth sensor element 34, which extends in particular into the grip area 27 of the grip device 26.

By means of the line 75, in particular almost completely encompassing the fifth sensor element 34 in the rear housing part 71, starting from the control element 10 to the connection point 72, undesired detections by the fifth sensor element 34 in the area of the rear housing part 71 are reliably prevented. By arranging the line 75 accordingly, only a selected area of the sensor element 34 or even several areas of the sensor element 34 can be shielded to the desired extent and the risk of undesired detection in this area or in these areas can be reliably prevented. The area of the sensor element 34 provided for detection can thus be determined very precisely.

In order to also reliably shield the area of the fifth sensor element 34 running in the metallic housing 70 and to prevent undesired detection in this area, the metallic housing 70 is grounded in the present case and connected to the negative pole of the accumulator 5 analogously to the line 75. For this purpose, a metallic element 80 or a metallic contact is provided in the area of the connection point 73, which is connected to the negative pole of the accumulator 5 via a connecting element 81 in the area of the rear housing part 71. This can reliably prevent a contact with the metallic housing 70 leading to a detection of the fifth sensor element 34.

Correspondingly, the sensor elements 30, 31, 32, 33, 34, 35 can be shielded to prevent undesired detection in selected areas in these areas, whereby one or more earthed further elements, for example a earthed line or a earthed housing part, can be provided for this purpose.

In an area 61 of the machine tool 1 in which the electric motor 4 is arranged, there are, for example, greater disturbances for the sensor elements 30, 31, 32, 33, 34, 35 than in an area 60 further away from the electric motor 4 To prevent the respective defined threshold value of the respective sensor element 30, 31, 32, 33, 34, 35 from being exceeded by such disturbances, provision can be made for the defined threshold values of the individual sensor elements 30, 31, 32, 33, 34, 35 differ from one another, whereby in particular those defined threshold values of The sensor elements 30, 31, 34, 35 arranged near the drive device 4 are greater than the defined threshold values in the sensor elements 32, 33 facing away from the drive device 4.

For example, it can be provided that the respective defined threshold value is composed of the sum of a touch value that is essentially identical for all sensor elements 30, 31, 32, 33, 34, 35 and a basic signal value that is dependent on the respective ambient conditions. The basic signal value is in particular higher the greater the interference in the area of the respective sensor element 30, 31, 32, 33, 34, 35.

It can be provided here that in particular the defined threshold values of the sensor elements 30, 31, 34, 35, which are located in the areas facing the drive device 4, are arranged as a function of the defined threshold values of the sensor elements 32, 33, which are determined by the drive device 4 remote areas are arranged, adjusted or calibrated. The setting or calibration of the defined threshold values of the sensor elements 32, 33 can take place at defined time intervals or continuously during operation of the machine tool 1 as a function of one or more of the defined threshold values of one or more of the sensor elements 30, 31, 34, 35.

8 shows an example of a section of an end region 41 of a sensor element 40 facing away from the control element 10, which is basically comparable to the sensor elements 30, 31, 32, 33, 34, 35 and, as an alternative or in addition to one or more of the sensor elements 30, 31, 32, 33, 34, 35 can be used. The end region 41 of the sensor element 40 here has two plate-shaped elements 42, 43, a first element 42 being arranged at a distance from and displaceable relative to the second element 43.

The first element 42 represents, for example, a base plate which is electrically and electronically connected to a line 44 of the sensor element 40, which in turn is provided for coupling to the control element 10. The first element 42 and the second element 43 can have a planar design, as shown in FIG. 8. In an alternative embodiment, it can also be provided that the elements 42 and 43 are designed differently and, for example, are bent so that the sensor element 40 can also be arranged in a simple manner, for example in the grip area 27. The sensor element 40 can, for example, partially or almost completely encompass the grip area 27 on the circumferential side, so that a defined grip strength in the grip area 27 can be determined by means of the sensor element 40. In the present case, the first element 42 and the second element 43 are connected to one another via a spring device 45 which converts the second element 43 into one of the first element

42 spaced position with force applied.

As an alternative or in addition to this, an in particular elastically deformable material can be arranged between the first element 42 and the second element 43, by means of which the elements 42, 43 are in particular connected to one another.

The first element 42 and the second element 43 are designed in particular with a metallic material. If a distance between the first element 42 and the second element 43 is changed, for example by means of an actuation element which can be operated by a user and which is preferably arranged in the holding area 22 and / or the grip area 27 of the machine tool 1, a current electrical La is correspondingly application of the sensor element 40 changed. This is due to the fact that the second element

43 together with the first element 42 represents a capacitor, the electrical charge of which varies as a function of a distance between the elements 42, 43 and increases with decreasing distance. The functional principle here corresponds to the procedure described in more detail above for determining a change in charge.

Analogous to the above explanations, a defined threshold value is provided for the electrical charge, the exceeding of which can be interpreted as an actuation of the sensor element 40 by the user. By means of the sensor element 40, depending on the choice of the spring constant of the spring device 45 or the choice of the elastically deformable material, a minimum force can be specified in a number of ways, with which the actuating element connected to the second element 43 can be actuated in order to achieve the defined threshold value exceed and lead the circuit breaker 21 in the manner described above in the active state. An unintentional transfer of the circuit breaker 21 from the inactive state to the active state can be reliably prevented in this way.

As can be seen in particular from FIGS. 2 to 5, the machine tool 1 has a main channel 50 running in the longitudinal direction L of the machine tool 1, which is essentially from a foot area 51 in which the accumulator 5 and the main control electronics 9 are located , extends up to the head region 24 of the machine tool 1. Cooling air is passed through the main channel 50, which air is sucked in through ventilation openings in the foot region 51 of the machine tool 1 by means of a fan and is passed in the longitudinal direction L through the main channel 50, in particular for cooling the electric motor 5. The respective sensor elements 30, 31, 32, 33, 34, 35 are here almost completely each arranged in an area separate from the main channel 50. The areas are preferably designed as separate channels 51, 52, 53, 54, with each sensor element 30, 31, 32, 33 being assigned a separate channel 51, 52, 53, 54. A single sensor element 30, 31, 32, 33 is arranged in each channel 51, 52, 53, 54, it also being possible for two or more sensor elements to be arranged at least in some areas in a channel. In addition to the sensor elements 30, 31, 32, 33, the sensor elements 34, 35 can also be assigned a separate channel in a comparable manner.

Each channel 51, 52, 53, 54 extends here essentially starting from the control element 10 to an end region of the respective sensor element 30, 31, 32, 33 remote from the control element 10, the channels 51, 52, 53, 54 in the present case are essentially completely separated or separated from the main channel 50.

The sensor elements 30, 31, 32, 33 are separated from the main duct 50 by the ducts 51, 52, 53, 54 in such a way that the sensor elements 30, 31, 32, 33 are safe from disturbing influences present in the main duct 50, for example in the form of moisture and / or dirt, for example conductive grinding dust, are protected. Such interfering influences could interfere with the functionality of the sensor elements 30, 31, 32, 33 and possibly lead to incorrect detection. This is reliably prevented by the arrangement of the sensor elements 30, 31, 32, 33 separate from the main channel 50 in the respective channels 51, 52, 53, 54.

In addition to the sensor elements 30, 31, 32, 33, in the present case the control element 10 is also separated from the main channel 50 and arranged in a separate area or a chamber 56. Thus, the control element 10, comparable to the sensor elements 30, 31, 32, 33, is protected from conditions present in the main channel 50 which could interfere with the functionality of the control element 10.

As a result of these measures, the risk of incorrect detection of one or more of the sensor elements 30, 31, 32, 33 due to the conditions present in the main channel 50 is greatly reduced in a simple manner.

In order to form the channels 51, 52, 53, 54 in a structurally simple manner, the housing 2 is in the present case designed in two parts such that each channel 51, 52, 53, 54 and the chamber 56 are preferably formed jointly by at least two parts of the housing 2 . This makes it easy to assemble the machine tool 1. In Fig. 10, an embodiment of a method for operating the machine tool 1 is shown by way of example.

The method begins with the start S, in particular when the user actuates the switch 20, for example. In a first step S1, the power switch 21 is set to the inactive state. The power switch 21 is preferably preset in the inactive state.

In a second step S2, the electrical charges of the respective sensor elements 30, 31, 32, 33, 34, 35, 40 are determined and these are compared in step S3 with the respectively assigned defined threshold values. In step S4 it is checked whether a predefined condition exists between the determined electrical charges and the respective threshold values of the sensor elements 30, 31, 32, 33, 34, 35, 40, as described in more detail above by way of example.

If the query in step S4 is negative and the predefined condition is not present, the circuit breaker 21 is transferred to the inactive state or left in the inactive state in step S5 and the method is continued with step S2.

If the query result in step S4 is positive, the circuit breaker 21 is switched to the active state or left in the active state in step S6, so that a user-side actuation of the switch 20 leads to an activation of the drive device 4. The method is then continued with step S2.

In step E, the method is ended in particular when there is no longer any user-side actuation.

Claims

PATENT CLAIMS

1. Hand-held machine tool (1) with a housing (2), wherein a drive device (4) for actuating a tool (3) that can be brought into operative connection with the machine tool (1) and a control device (8) for actuating the drive device (4 ) is provided, and wherein the control device (8) is designed with a control element (10), and wherein at least one capacitive sensor element (30, 31, 32, 33, 34, 35, 40) operatively connected to the control device (10) is provided, characterized in that the at least one sensor element (30, 31, 32, 33, 34, 35, 40) and / or the control element (10) at least regionally, in particular almost completely from a main channel (50) of the machine tool ( 1), in which the drive device (4) is angeord net, is separated.

2. Hand-held machine tool according to claim 1, characterized in that the sensor element (30, 31, 32, 33, 34, 35, 40) and / or the control element (10) in egg nem from the main channel (50) completely separate area ( 51, 52, 53, 54, 56) is arranged.

3. Hand-held machine tool according to one of claims 1 or 2, characterized in that at least one sensor element (30, 31, 32, 33, 34, 35, 40) is arranged in a channel (51, 52, 53, 54).

4. Hand-held machine tool according to one of the preceding claims, characterized in that several sensor elements (30, 31, 32, 33, 34, 35, 40) are provided, each sensor element (30, 31, 32, 33, 34, 35, 40) is at least partially in a separate channel (51, 52, 53, 54) separated from the main channel (50).

5. Hand-held machine tool according to one of the preceding claims, characterized in that at least two sensor elements (30, 31, 32, 33, 34, 35, 40) are seen in front, which are at least partially arranged together in a channel.

6. Hand-held machine tool according to one of the preceding claims, characterized in that at least one sensor element (30, 31, 32, 33, 34, 35, 40) at least is designed as a line at least in some areas.

7. Hand-held machine tool according to one of the preceding claims, characterized in that the control element (10) is arranged in a chamber (56) which is preferably separated from the at least one channel (50, 51, 52, 53, 54).

8. Hand-held machine tool according to one of the preceding claims, characterized in that the housing (2) is designed at least in two parts, we at least one channel (50, 51, 52, 53, 54) and / or the chamber (56) through at least two parts of the housing (2) is formed together.

9. Hand-held machine tool according to one of the preceding claims, characterized in that the control element (10) has a control unit and a signal generator.

10. Hand-operated machine tool according to one of the preceding claims, characterized in that a power switch (21) operatively connected to the control device (8) is provided, the control device (8) for transferring the circuit breaker (21) between an inactive state and an active one State is executed, whereby a user-side actuation of the circuit breaker (21) in the active state of the circuit breaker (21) leads to an actuation of the drive device (4).