WO2025201899A1

WO2025201899A1 - Handheld electric tool

Info

Publication number: WO2025201899A1
Application number: PCT/EP2025/056884
Authority: WO
Inventors: Michael Lacher; Christian Koschel; Helmut Hummel
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 2024-03-28
Filing date: 2025-03-13
Publication date: 2025-10-02
Anticipated expiration: 2026-09-28
Also published as: EP4624102A1

Abstract

The present invention relates to a handheld electric tool, comprising a drive device by means of which an insert operably connectable to the electric tool can be actuated, and a controller for actuating the drive device, and at least one capacitive sensor element operably connected to the controller. The electric tool further comprising at least one gripping part, the gripping part comprising a gripping region defining a gripping direction, for holding and guiding the electric tool by means of one or both hands of a user contacting the gripping region at least partially around the gripping direction. A length of the at least one sensor element in the gripping direction is not less than a length of the gripping region.

Description

Handheld electric tool

TECHNICAL FIELD

The invention relates to a hand-held electric tool comprising a housing, with a drive device for actuating an insert operably connectable to the electric tool and a controller for actuating the drive device being provided.

BACKGROUND ART

A handheld electric tool designed with a capacitive sensor is known from practice. By means of a capacitive sensor, for example, a power switch may be activated, and then a drive device may be actuated by means of a user-activable switch. A so-called dead man function may be provided by means of a capacitive sensor. A capacitive sensor, for example, is arranged in a gripping region of an electric tool, and may detect a user’s hand positioned in the gripping region.

It is known that, in a handheld electric tool with a capacitive sensor, the user’s hand is detected when it is very close to the sensor and a defined threshold is exceeded. However, in this case, the sensitivity of the capacitive sensor element is generally higher than that of the detected object (e.g. hand, finger, etc.), so the sensor electrode will couple with the approaching hand before contact with the fingertip, thereby producing an undesired proximity effect. It is difficult to distinguish between fingertip contact capacitance and proximity capacitance, and this might result in erroneous touch detection or loss/delay of no-touch detection. All this will increase the complexity of the sensor element as well as the sensor electronics.

SUMMARY OF THE INVENTION An object of the present invention is to provide a handheld electric tool, having a sensitive and reliable capacitive sensor system, which can reduce the risk of erroneous detection.

A handheld electric tool, comprising a housing; a drive device for actuation; a controller for controlling the drive device; and at least one capacitive sensor element operably connected to the controller. The electric tool further comprises at least one gripping part, the gripping part comprising a gripping region defining a gripping direction, for holding and guiding the electric tool by means of one or both hands of a user contacting the gripping region at least partially about the gripping direction. A length of the at least one sensor element in the gripping direction is not less than an expected maximum length of the object to be detected (e.g. the user’s hand). Thus, when the user’s hand holds the electric tool with the gripping region, the effective parallel area of touch contact points depends on the size of the object to be detected (the user’s hand) rather than the area of the sensor, because the sensor length is designed to be larger than the expected maximum length of the object to be detected. Increasing the size of the sensor enables the user to place contact points anywhere in the gripping region, further the sensor element will be very sensitive to minor movements of the hand/fingers (the objects to be detected).

Alternatively, a length of the at least one sensor element in the gripping direction is not less than 50%, preferably not less than 80% of the length of the gripping region. It is assumed that the user hand at least grips 50% of the whole length of the gripping portion, but usually the user’s hand would not hold the whole gripping portion, as some tools are quite long. Therefore, the length of sensor element shall be larger than the object to be detected, to improve the accuracy of sensing the user’s hand on the gripping portion.

The sensor element is designed to have a changing sensitivity in the direction of the sensor length, so that the sensor element will be sensitive to minor movements of the hand/fingers (the objects to be detected).

The length of the at least one sensor element in the gripping direction is much greater than a width thereof, the width being the dimension of the sensor element substantially perpendicular to the gripping direction. Thus, multiple sensor elements can be arranged perpendicular to the gripping direction, so as to meet different control logic requirements of the controller. Moreover, since the length of the sensor element is much greater than the width, the sensor systems are designed only as wide as needed to gain the expected sensing area and kept as small as possible to avoid simultaneous activations of signals.

Preferably, two or more sensor elements are provided in the gripping region, substantially arranged in parallel in the gripping direction. It may be provided that, for example, when a predetermined condition exists between a determined first charge of a first sensor element and a determined and detected second charge of a second sensor element, actuation of the drive device and/or limited activation of the drive device is realized by means of the controller. With this arrangement, for example, the user needs to grip the electric tool in different regions in order to allow operation of the drive device. Thus, a desired gripping position may be specified, so as to realize safe operation of the electric tool in a simple way. It may be provided that the sensor elements are arranged so that the user needs to touch different regions of the electric tool with his hand. For example, it may be provided that one region is arranged in an upper portion of the electric tool and one region is arranged in a lower portion of the electric tool, such that, for example, one region may be touched with the thumb and the other region with the remaining fingers. If regions associated with the sensor elements are far apart, it may also be provided that the electric tool can be operated only when the user grips the electric tool with both hands in these regions.

According to an embodiment of the present invention, the at least one sensor element is substantially linear in the gripping direction. Thus, the sensor element has a simple structure, and is convenient to manufacture and install, thus achieving cost optimization.

According to another embodiment of the present invention, the at least one sensor element is substantially in the form of a curve, or a number of polylines joined head-to- tail, in the gripping direction. Thus, the sensor element has a larger sensor length over the same length in the gripping direction, thereby further increasing sensitivity to minor movements of the hand or fingers.

According to another embodiment of the present invention, the at least one sensor element is substantially in the form of multiple consecutive blocks in the gripping direction, each block being connected to an adjacent block at a corner thereof. According to another embodiment of the present invention, the at least one sensor element comprises a main body extending in the gripping direction, and a number of discrete ribs extending substantially perpendicular to the gripping direction. Sensor elements designed in this way are especially favourable for detecting minor movements of the fingertips.

As stated above, the electric tool comprises at least one gripping part, wherein a first gripping part is formed on the housing, a first gripping region substantially extends from a portion of the housing that encloses the drive device to a rear end of the housing that is connected to a power source, and a first gripping direction substantially extends in a longitudinal direction from the front towards the rear. A first gripping region is arranged on the housing, and it is possible to determine whether the electric tool is currently being held by the user in a desired way by means of a detection signal of a defined sensor element arranged in a corresponding region of the electric tool.

Alternatively, or in addition to this, the electric tool may further comprise a second gripping part connected to the housing, the second gripping region substantially extending along an outer peripheral face of the second gripping part. Depending on the category and characteristics of the electric tool, the second gripping part here may be an independent gripping part, for example a D-shaped or T-shaped handle formed integrally with the housing, or may be an attached handle which is present together with the first gripping part mentioned above.

The handheld electric tool may relate to various handheld electric tools, for example, a grinder, such as an angle grinder; a saw machine, such as a reciprocating saw, jigsaw, circular saw or chainsaw; or a drilling machine, chisel hammer, etc.

An electrode of a capacitive sensor must be large enough so that the sensor can be activated without any need for the user’s finger to be placed on the touch contact point precisely. If the size of the sensor electrode is smaller than the user’s fingertip, then sensitivity will decrease due to the decreased effective area. For example, in the case of a capacitive sensor with a diameter of 8 mm, the touch contact point thereof has a diameter of 8 mm, and the maximum sensitivity is limited to this size even if the object to be detected (hand, finger) is larger. In the electric tool of the present invention, increasing the size of the sensor enables the user to place the contact point at any position in the sensor region, without lowering sensitivity. The sensor region is larger than the gripping region contacted by the hand, so the sensor element is very sensitive to minor movements of the hand. Sensor signals are analysed, and signal changes caused by minor movements of the hand/fingers (the objects to be detected) are detected; this will add extra touch information to a default touched/not-touched result through large signal analysis. For example, if there is no signal change of a typical minor movement, the controller actuates the drive device and/or performs limited activation of the drive device.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional advantages may be found in the description of the drawings below. Embodiments of the present invention are shown in the drawings. The drawings, Description and claims contain many combined features. Those skilled in the art will also conveniently consider these features separately, and combine them to form additional significant combinations. In the drawings:

Fig. 1 is a highly simplified longitudinal sectional view of a handheld electric tool designed as an angle grinder, wherein an insert is arranged on a driven shaft of the angle grinder.

Fig. 2 is a longitudinal sectional view of the angle grinder according to Fig. 1 .

Fig. 3 is a simplified three-dimensional view of the angle grinder showing an attached handle.

Fig. 4 is a simplified schematic drawing of a sensor element arranged in a gripping region according to an embodiment of the present invention.

Fig. 5 is a simplified schematic drawing of a sensor element arranged in a gripping region according to another embodiment of the present invention.

Fig. 6 is a simplified schematic drawing of a sensor element arranged in a gripping region according to another embodiment of the present invention. Fig. 7 is a simplified schematic drawing of a sensor element arranged in a gripping region according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Figs. 1 - 3 show a handheld electric tool 1 according to the present invention, designed as an angle grinder in the illustrations shown. According to alternative embodiments, the electric tool 1 may also be designed as a drilling machine, a hammer drill, a saw, a chisel hammer, etc.

The electric tool 1 designed as an angle grinder in the drawings has a housing 2 and an insert 3; the insert 3 is for example designed as a cutting disc or abrasive wheel, and may be detachably connected to a driven shaft 7 of the electric tool 1 . A drive device 4 (which rotates in this case) for actuating the insert 3 is arranged inside the housing 2 together with a gear mechanism 6. The drive device 4 designed as an electric motor for example, the gear mechanism 6 and the driven shaft 7 to which the insert 3 is operably connected are arranged relative to each other and interconnected, such that torque generated by the electric motor 4 may be transferred to the gear mechanism 6, and finally to the driven shaft 7. In this case, a free rotating end of the driven shaft 7 protruding downwards from the housing 2, for example, is connected by means of a clamping apparatus (not shown in detail) to the insert 3, here designed as a cutting disc.

The insert 3 may be actuated by a drive device 4 (in particular designed as an electric motor), and supplied with current by means of a battery 5 connectable to the electric tool 1 . Like the housing 2, the battery 5 is not shown in all of the drawings. According to an alternative embodiment (not shown in the drawings), the electric tool 1 may also be supplied with current from a power supply network by means of a power cable.

The electric tool 1 also has a controller 8; in this exemplary embodiment, the controller 8 is designed to have a main control electronics 9 and a control element 10. The control element 10 is preferably designed as a printed circuit board, and is electrically connected to the main control electronics 9; in the present case, the main control electronics is arranged in a region of the battery 5. A user-actuated switch 20 is connected to the main control electronics 9 by means of a power switch.

In a schematic embodiment of the electric tool 1 designed as an angle grinder, the housing 2 comprises a head region 24 facing towards the insert 3, and a bottom region 25 for connecting the battery 5. The inside of the housing 2 forms a cavity, which is provided with the drive device 4 (e.g. electric motor) for actuating the insert and the controller 8 for controlling the drive device 4. Most of the housing 2 is formed of an insulating plastic. For example, as shown in Fig. 2, from a front part 60 housing the drive device 4, to a rear part 62 housing the control element 10, all the way to the bottom region 25 for connecting a power source, the housing is formed of insulating plastic, whereas the head region 24 is preferably made of a metal material. A front end of the housing 2 is connected to the head region 24; preferably, the head region 24 is formed of metal.

The housing 2 forms a first gripping part 22, the first gripping part 22 having a first gripping region 23. For example, a portion of the outer periphery of the housing 2 that extends from a portion covering the drive device 4 to the bottom region 25 connected to the power source is defined as the first gripping region 23, and used for holding and guiding the electric tool 1 with one or both hands of the user. Furthermore, when one or both hands of the user are performing control in the first gripping region, the thumb and the remaining four fingers separately contact the outer periphery of the substantially tubular first gripping part 22, with the palm facing towards the inside of the housing 2, and the encircling hand defines a first gripping direction X1 extending substantially along a central axis of the tubular shape. In addition, when the electric tool 1 is held with the first gripping region 23, the user-operable switch 20 is associated with the first gripping region 23.

As an alternative solution or in addition to this, the electric tool 1 may have a second gripping part 26, wherein the second gripping part 26 may be connected to the housing 2 of the electric tool 1 . Fig. 3 shows a second gripping part 26 of this type; as shown in Figs. 2 and 3, it may be detachably connected to the housing 2 in a region of a connecting point 28. An outer peripheral face of the second gripping part 26 is designed as a second gripping region 27, the second gripping region 27 substantially extending along the entire length of the second gripping part 26, and a second gripping direction X2 is the direction of an axis faced by the palm of the hand when the outer peripheral face of the second gripping part 26 is encircled with the hand.

It must be explained that, according to a schematic embodiment of the present invention, when the electric tool 1 is designed as an angle grinder, the electric tool 1 may simultaneously have the first gripping part 22 and the second gripping part 26, and by separately arranging sensor elements of the first gripping part 22 and the second gripping part 26, detects whether the angle grinder is currently being grasped with the first gripping region 23 and the second gripping region 27, and for example, switches the power switch 21 to the activated state only when this is the case. Alternatively, it is also possible for the electric tool 1 to only have the first gripping part 22 or the second gripping part 26. For example, when the electric tool 1 is designed as an angle grinder, in particular a small angle grinder, the electric tool 1 may only have the first gripping part 22, in which case it is only necessary to detect whether the first gripping region is gripped correctly in order to switch to the activated state. Alternatively, when the electric tool 1 is designed as a large angle grinder or another category of tool, such as a circular saw, a reciprocating saw or an electric hammer, etc., the electric tool 1 may only have the second gripping part 26; in this case, the second gripping part 26 may for example be a D-shaped or T-shaped handle formed integrally with the housing, or may be an independent attached handle connected to the housing. When the electric tool 1 is designed as a chainsaw, breaker, etc., the electric tool 1 also comprises two gripping parts, e.g. a main handle and an auxiliary handle, or left and right handles. Depending on the category and application of the electric tool 1 , activation conditions of the drive device are set; for example, when a predetermined condition is met by a sensor signal detected by at least one sensor element arranged in the first gripping region and/or second gripping region, actuation of the drive device 4 and/or limited activation of the drive device 4 is realized by means of the controller 8.

Sensor elements 31 , 32, 33, 34 may be directly formed in a housing of the first gripping part 22 and/or second gripping part 26, said housing being formed of an insulating material. Preferably, the at least one sensor element 31 , 32, 33, 34 is formed of conductive plastic, and formed integrally with the housing 2 formed of insulating plastic. Alternatively, the sensor elements 31 , 32, 33, 34 may also be arranged in a region close to an inner surface of the first gripping part 22 and/or second gripping part 25. Furthermore, the control element 10 is operably connected to at least one sensor element 31 , for example by line or direct contact. In this embodiment, the control element 10 in particular has a control unit and a signal generator, wherein the signal generator is in particular designed for charging the sensor elements 31 , 32, 33, 34 at a defined voltage. The control unit is preferably designed for detecting a change in charge in at least one sensor element, e.g. detecting the presence of a hand if the determined charge is greater than a defined threshold.

The electric tool 1 is described in further detail below, using a vertical direction H, a longitudinal direction L and a transverse direction Q. In this embodiment, the longitudinal direction L is the direction between the battery 5 and the head region 24, and substantially represents the first gripping direction X1. In the present case, the vertical direction H substantially corresponds to the direction of extension of the driven shaft 7, and the transverse direction Q is substantially perpendicular to the longitudinal direction L and the vertical direction H and substantially represents the second gripping direction X2.

Referring to Figs. 1 - 3, the first sensor element 31 is arranged in a region close to an inside surface of the housing 2, and the first gripping direction X1 substantially extends in a griping region 23, with the length of the first sensor element 31 in the first gripping direction X1 being not less than 50% of the length of the first gripping region 23. Preferably, the length of the first sensor element 31 in the first gripping direction X1 is not less than 80% of the length of the first gripping region 23. More preferably, the length of the first sensor element 31 in the first gripping direction X1 is equal to or greater than the length of the first gripping region 23.

The first sensor element 31 extends in the first gripping direction X1 substantially from a region where the electric motor 4 is arranged to the bottom region 25 where the battery 5 is arranged; more preferably, the first sensor element 31 extends continuously in the longitudinal direction L from the front end of the housing 2 to the bottom region, the front end being connected to a gearbox 24 and the bottom region being connected to the battery 5.

Anyway, the length of the first sensor element 31 in the gripping direction is not less than an expected maximum length of the object to be detected (e.g. the user’s hand). Thus, when the user’s hand holds the electric tool 1 with the first gripping region 23, the effective parallel area of touch contact points depends on the size of the user’s fingertips rather than the area of the sensor, because the sensor region is designed to be larger than the object being detected (the user’s hand). Increasing the size of the sensor enables the user to place contact points anywhere in the sensor region, so the sensor region will be very sensitive to minor movements of the hand/fingers (the objects to be detected). Furthermore, the length of the sensor element in the gripping direction is key to deciding the size of the sensor region; only when the length of the sensor element in the gripping direction is not smaller than a gripping region where the hand might grip the electric tool, can it be ensured that minor movements of the hand can be detected.

The sensor element 31 , 32, 33, 34 is designed to have a changing sensitivity in the direction of the sensor length, so that the sensor element will be sensitive to minor movements of the hand/fingers (the objects to be detected). When the user’s hand grips the first gripping region 23, the first gripping direction X1 is substantially parallel to the longitudinal direction of the electric tool 1 , so the dimension of the first sensor element 31 in the first gripping direction is defined as the length of the first sensor element 31 ; in this case, the dimension of the first sensor element 31 in a direction substantially perpendicular to the first gripping direction X1 (i.e. substantially corresponding to the direction of extension of the driven shaft 7) is defined as the width B of the sensor element. Preferably, L » B, so multiple sensor elements can be arranged perpendicular to the gripping direction, so as to meet different control logic requirements of the controller.

Preferably, there are two or more sensor elements 31 , 32, 33, 34. For example, the electric tool 1 further comprises a second sensor element 32, which is also arranged in the housing 2 or arranged in a region close to a surface of the housing 2, and the first gripping direction X1 substantially extends in the first gripping region 23, with the length of the second sensor element 32 in the first gripping direction X1 being not less than 50% of the length of the first gripping region 23. Preferably, the length of the second sensor element 32 in the first gripping direction X1 is not less than 80% of the length of the first gripping region 23. More preferably, the length of the second sensor element 32 in the first gripping direction X1 is equal to or greater than the length of the first gripping region 23. The first sensor element 31 and the second sensor element 32 are respectively arranged in an upper region and a lower region of the housing. The length L of the sensor element is much larger than the width B thereof; therefore, perpendicular to the first gripping direction, the elongated tubular housing has enough space to arrange two or more sensor elements in the up-down direction thereof, such that simultaneous activation of signals is avoided to the maximum extent while achieving the desired high sensitivity to minor movements of the hand. Preferably, the first sensor element 31 and the second sensor element 32 are substantially arranged in parallel in the first gripping direction X1 , such that the configuration of the sensor elements simultaneously has reliable sensitivity as simply as possible. For example, it may be provided that when a predetermined condition exists between a determined first charge of the first sensor element 31 and a determined and detected second charge of the second sensor element 32, actuation of the drive device 4 and/or limited activation of the drive device is realized by means of the controller 8. With this arrangement, the user needs to grip the electric tool 1 in the first gripping region 23 in order to allow operation of the drive device 4. Furthermore, a desired gripping position may be specified, so as to realize safe operation of the electric tool in a simple way. For example, the sensor elements are arranged so that the user needs to touch different regions of the electric tool with his hand. For example, it may be provided that one region is arranged in an upper region of the electric tool and one region is arranged in a lower region of the electric tool, such that, for example, one region may be touched with the thumb and the other region with the remaining fingers. If regions associated with the sensor elements are far apart, it may also be provided that the electric tool can be operated only when the user grips the electric tool with both hands in these regions.

It will be understood that, depending on the size of the drive device and the design of the housing, the cross-sectional size of the housing 2 in the vertical direction H thereof may vary; for example, as shown in Fig. 2, the diameter of a front housing 60 containing the drive device 4 is greater than the diameter of a cavity portion 62 containing the control element 10, and a transitional part 61 is provided between the two different diameter portions. Preferably, the first sensor element 31 and/or the second sensor element 32 also vary/varies with the shape of the housing; therefore, the first sensor element 31 and/or the second sensor element 32 is/are substantially parallel in a gripping region of the front housing 60 covering the drive device 4, or also substantially parallel in the cavity portion 62 at a rear part of the gripping region, but not parallel in a region of the transitional part 61 . Referring to Fig. 3, a third sensor element 33 is arranged in a handle housing of the second gripping part 26 or in a region close to an inner surface of the handle housing of the second gripping part 26. The third sensor element 33 extends along the handle length of the entire second gripping part 26; that is to say, in the extension of the third sensor element 33 in the second gripping region 27 formed by the second gripping part 26, the second gripping direction X2 is substantially parallel to the transverse direction Q. Moreover, the length L3 of the third sensor element 33 in the second gripping direction X2 is not less than 50% of the length of the second gripping region 27, preferably, not less than 80% of the length of the second gripping region 27. More preferably, third sensor element 33 in the second gripping direction X2 is not less than the whole length of the second gripping region 27. The third sensor element 33 is designed so that the drive device can be activated only when the second gripping region 27 is arranged on the housing 2 in a desired manner and a signal is detected to exceed a relevant defined threshold.

Furthermore, a fourth sensor element 34 may also be arranged in the second gripping part 26, e.g. disposed in parallel with the third sensor element 33 and spaced apart therefrom, the third sensor element 33 and the fourth sensor element 34 both having L greater than B, such that the second gripping part 26 acting as an attached handle here can also achieve the desired high sensitivity to minor movements of the hand.

Referring to Fig. 4, according to an embodiment of the present invention, the at least one sensor element 31 , 32, 33, 34 is substantially linear in the gripping direction. Thus, the sensor element has a simple structure, and is convenient to manufacture and install, thus achieving cost optimization.

Referring to Fig. 5, according to another embodiment of the present invention, the at least one sensor element 31 , 32, 33, 34 is substantially in the form of a curve, or a number of polylines joined head-to-tail, in the gripping direction. Thus, the sensor element has a larger sensor region over the same length in the gripping direction, thereby further increasing sensitivity to minor movements of the hand or fingers.

Referring to Fig. 6, according to another embodiment of the present invention, the at least one sensor element 31 , 32, 33, 34 is substantially in the form of multiple consecutive blocks in the gripping direction, each block being connected to an adjacent block at a corner thereof. A sensor element designed in this way is especially favourable for detecting minor movements of the fingertips.

Referring to Fig. 7, according to another embodiment of the present invention, the at least one sensor element 31 , 32, 33, 34 comprises a main body extending in the gripping direction, and a number of discrete ribs extending substantially perpendicular to the gripping direction.

The sensor elements 31 , 32, 33, 34 are presently all designed as capacitive sensor elements, it being possible to determine a change in charge in the relevant sensor element 31 , 32, 33, 34 in conjunction with the control element 10. To determine a change in charge, it can be provided that the relevant sensor element 31 , 32, 33, 34 is charged by the control device 8 or the control element 10 up to a defined voltage and the relevant sensor element 31 , 32, 33, 34 is then discharged. It can be provided in this case, for example, that a capacitor which has a small capacitance comparable to the typical charging of a sensor element 31 , 32, 33, 34 is associated with the control element 10 and it is determined how often this capacitor can be charged by the relevant sensor element 31 , 32, 33, 34 until the relevant sensor element 31 , 32, 33, 34 is completely discharged.

The charge that the relevant sensor element 31 , 32, 33, 34 can absorb is substantially constant. A human hand has a capacitance which is added to the capacitance of the sensor element 31 , 32, 33, 34 when the human hand comes within close range of the relevant sensor element 31 , 32, 33, 34. Since the relevant sensor element 31 , 32, 33, 34 is charged to a constant voltage, the charge absorbed by the sensor element 31 , 32, 33, 34 increases for example in the presence of a hand so that, when the relevant sensor element 31 , 32, 33, 34 is discharged, a greater amount of charge is present than in a state without the human hand.

It can be provided that the control element 10 transfers the power switch 21 from the inactive state to the active state if at least one determined electrical charge of a sensor element 31 , 32, 33, 34 or multiple determined electrical charges of different sensor elements 31 , 32, 33, 34 exceeds the respectively associated threshold value. Thus, a prerequisite for transferring the power switch 21 from the inactive state to the active state can be that the charge determined by the third sensor element 33 exceeds the corresponding threshold value and/or the charge determined by the fourth sensor element 34 exceeds the corresponding threshold value, thus requiring the second grip part 26 to be gripped to activate the power switch 21 . It can be determined, for example, whether the machine tool 1 is being held by a user in the desired manner. For example, whether the machine tool is being held in the holding region 22 and in the grip region 27 and the power switch 21 is transferred to the active state only in this case.

As an alternative or in addition to this, it can be provided that analysis of the sensor signal and detection of the signal changes caused by the small movements of the hand / finger (object to be detected), this adds a second touch information to the default touched/ untouched result by large signal analysis. The electric tool can be additional switched off (untouched) if there are no typical small signal changes.

It can also be provided that the power switch 21 is transferred from the active state back to the inactive state if the electrical charge determined by a sensor element 31 , 32, 33, 34 falls below the respectively defined threshold value, since this is due, for example, to a removal of a hand from the first gripping region 23 or the second grip region 27 and thus an undesirable operating state.

In an alternative embodiment, it can also be provided that simply any desired combination of the sensor elements 31 , 32, 33, 34 is provided. As an alternative to this, further sensor elements can also be provided, which 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.

As described above, although exemplary embodiments of the present invention have been explained herein with reference to the drawings, the present invention is not limited to the specific embodiments described above, and may have many other embodiments. The scope of the present invention should be defined by the claims and their equivalents.

Claims

PATENT CLAIMS

1. Handheld electric tool (1 ), comprising a housing (2); a drive device (4) for actuating an insert operable connection with the electric tool; a controller (8) for controlling the drive device (4); and at least one capacitive sensor element (31 , 32, 33, 34) operably connected to the controller (10), the electric tool further comprising at least one gripping part (22, 26), the gripping part (22, 26) comprising a gripping region (23, 27) defining a gripping direction (X1 , X2), for holding and guiding the electric tool (1) by means of one or both hands of a user contacting the gripping region (23, 27) at least partially around the gripping direction (X1 , X2), characterized in that a length of the at least one sensor element (31 , 32, 33, 34) in the gripping direction (X1 , X2) is not less than an expected maximum length of the object to be detected.

2. Handheld electric tool (1 ), comprising a housing (2); a drive device (4) for actuating an insert operable connection with the electric tool; a controller (8) for controlling the drive device (4); and at least one capacitive sensor element (31 , 32, 33, 34) operably connected to the controller (10), the electric tool further comprising at least one gripping part (22, 26), the gripping part (22, 26) comprising a gripping region (23, 27) defining a gripping direction (X1 , X2), for holding and guiding the electric tool (1) by means of one or both hands of a user contacting the gripping region (23, 27) at least partially around the gripping direction (X1 , X2), characterized in that a length of the at least one sensor element (31 , 32, 33, 34) in the gripping direction (X1 , X2) is not less than 50% of the length of the gripping region (23, 27), preferably not less than 80% of the length of the gripping region (23, 27).

3. Handheld electric tool according to Claim 1 or 2, characterized in that the sensor element (31 , 32, 33, 34) is designed to have a changing sensitivity in the direction of the sensor length.

4. Handheld electric tool according to Claim 1 or 2, characterized in that the length of the sensor element (31 , 32, 33, 34) in the gripping direction (X1 , X2) is much greater than a width thereof, the width being the dimension of the sensor element substantially perpendicular to the gripping direction (X1 , X2).

5. Handheld electric tool according to Claim 4, characterized in that two or more sensor elements (31 , 32, 33, 34) are provided in the gripping region (23, 27), substantially arranged in parallel in the gripping direction (X1 , X2).

6. Handheld electric tool according to any one of Claims 1 - 5, characterized in that the sensor element (31 , 32, 33, 34) is substantially linear in the gripping direction (X1 , X2).

7. Handheld electric tool according to any one of Claims 1 - 5, characterized in that the sensor element (31 , 32, 33, 34) is substantially in the form of a curve, or seeral polylines joined head-to-tail, in the gripping direction (X1 , X2).

8. Handheld electric tool according to any one of Claims 1 - 5, characterized in that the sensor element (31 , 32, 33, 34) is substantially in the form of multiple consecutive blocks in the gripping direction (X1 , X2), each block being connected to an adjacent block at a corner thereof.

9. Handheld electric tool according to any one of Claims 1 - 5, characterized in that the sensor element (31 , 32, 33, 34) comprises a main body extending in the gripping direction (X1 , X2), and a number of discrete ribs extending substantially perpendicular to the gripping direction (X1 , X2).

10. Handheld electric tool according to any one of the preceding claims, characterized in that a first gripping part (22) is disposed on the housing (2), a first gripping region (23) substantially extends from a portion of the housing that encloses the drive device (4) to a bottom region (25) of the housing that is connected to a power source, and a first gripping direction (X1 ) substantially extends in a longitudinal direction from the front towards the rear.

11. Handheld electric tool according to any one of the preceding claims, characterized in that a second gripping part (26) is detachably connected to the housing (2), and a second gripping region (27) substantially extends in the gripping direction (x2) along an outer peripheral face of the second gripping part (26).