EP0303651B1 - Process for interrupting the operation of a hand tool, in particular percussion and/or rotation thereof - Google Patents

Abstract

In a process for switching off a drill hammer and/or a chisel hammer during idling, a clutch (28) arranged at least in the percussion drive line is automatically released when the idling position is reached. The point at which the tool (24) reaches a position on the idling section is detected and the clutch (28) is automatically released when this position is reached and re-engaged when the tool leaves this position. To this end, an idling sensor (30) releases and re-engages the clutch (28) electromechanically through a control device. Hence, no additional manipulations or clutching-in efforts are required of the operator holding the drill hammer in order to start or stop the tool, which results in short idling periods.

Description

State of the art

The invention is based on a method for interrupting the drive activity of a handheld power tool according to the generic preamble of claims 1 or 3. EP 150 669 A2 already discloses such a handheld power tool with a container accommodated in its interior, in which an electrically conductive, liquid mass is located. This mass is penetrated by a magnetic field, which induces an electrical voltage that can be picked up from electrodes when the machine rotates. The measurement of the inertial forces is only possible with a relatively large expenditure on equipment. In addition, if the machine is intended to move, the safety clutch can also be triggered incorrectly.

It is also known from DE 24 49 191 C2 to arrange a non-positive clutch in the form of a cone clutch in the drive train of the striking mechanism, which clutch is normally disengaged and separates the striking mechanism from the drive train. However, if the operator presses the hand-held power tool against the rock, the tool holder is moved backwards into the hand-held power tool via the tool. This displacement movement is used via a displacement of the rotary sleeve serving for the rotary drive for the axial displacement of the driven shaft, as a result of which the cone coupling half, which is non-rotatable thereon, is pressed axially against another cone coupling half of the striking mechanism and so, when the coupling is engaged, the striking mechanism is now also driven. The clutch is thus automatically engaged depending on a force that the operator has to apply by firmly pressing the hand tool. This makes handling difficult. In addition, relatively large idling distances must be provided on the machine side, which is not only impractical for handling, but also increases the axial length.

It is also known (DE-PS 28 20 128) to arrange a safety clutch as a clutch in the drive train, which responds when a certain transmitted torque is reached and then separates the rotary drive. Such safety couplings are e.g. designed as slip clutches, friction clutches or releasable clutches. Such safety clutches respond depending on the force. This works well if the user of the hand-held machine tool is prepared for the moment that suddenly occurs in the event of a blockage and the hand-held machine tool is constantly holding the corresponding counter-moment in anticipation of this malfunction. However, these requirements are often not met, so that e.g. twisted or even injured wrists and arms occur repeatedly when using such handheld power tools, in particular rotary hammers. As a preventive measure, on the other hand, it is also known to set the response torque of the safety clutches described as lower, with the result that, with larger drill diameters or longer drilling, the torque required for working is not achieved and the safety clutch constantly responds. In a disadvantageous way, the performance of the hand-held power tool cannot be fully utilized. Adjustable safety clutches also do not offer a satisfactory solution. You can work in the upper torque range, but you have to expect a correspondingly larger torque surge in the event of a lock.

It is also known (DE-OS 35 11 437) to arrange force measuring elements within the hand-held power tool for the reasons mentioned, which react when a predetermined transmitted torque is reached and generate a signal. This should serve in a non-resolved manner to generate control functions and be used, for example, to switch off the energy supply, to actuate a clutch or brake and the like. Piezo-ceramic ones are addressed as force measuring elements. Even with this known method, one is stuck in the idea that, as overload variables for automatic disengagement, e.g. a clutch, as in the described safety clutches, force-dependent sizes are used. However, this does not eliminate the disadvantages described above.

Advantages of the invention

The method according to the invention with the characterizing features of claim 1 has the following advantages. Since the achievement of a travel position of the tool or a translationally moving part of the striking mechanism located on the idling distance is recorded as a variable and the clutch is automatically disengaged when this travel position is reached and automatically engaged when leaving this travel position, there is an automatic idle shutdown or automatic restart, without the user of the hand tool having to apply any additional operating forces or, in particular, engagement forces. Rather, the disengagement of the clutch depends solely on the displacement of the tool forward into the idle position, just as the engagement of the clutch again depends solely on the fact that the tool is moved backwards from this idle position to the position corresponding to the striking mode. The user can therefore work loosely and relaxed, without having to constantly apply special pressing forces to maintain the percussion drive. The handling of the hand machine tool is considerably simplified. Greater ease of use is achieved. It is also advantageous that any other idling devices or catching devices are unnecessary and that the method according to the invention enables almost any short idling distances.

The idle travel can thus be significantly reduced, which leads to a faster response and to a more direct operation of the hand tool. Depending on the design of the hand-held power tool, a reduction in the axial length in the axial direction of the tool holder is also possible. Furthermore, the prerequisites have been created for simplifying the coupling, if necessary, since it is not absolutely necessary to use a cone coupling with cone halves that can be pressed axially against one another.

In addition, the following advantages can be achieved with the method according to the invention with the characterizing features of claims 3, 4 or 5. Since as a size - here as an overload size - a movement size of the hand-held hand tool is detected in the room, the z. B. can consist of a path and / or a speed and / or an acceleration, and since the clutch is automatically disengaged when a predetermined value of such a movement size is exceeded, there is always the same safety for the user of the hand tool, regardless of the drive torque Hand tool that the user applies with the holding torque. The user does not need to have a holding moment that is far too large for most of the time in anticipation of a block. Rather, he can work loosely and relaxed, without fear of being surprised by a sudden blockage and z. B. in a hammer drill during drilling operation by hurling the hammer when blocking the drill, z. B. hooking the drill in stone, concrete or the like. To be injured.

The invention is based on the fundamental knowledge that the pivoting movement of the hand-held power tool, in particular a rotary hammer, which occurs when a rotating tool is blocked, itself as a signal for the interruption of the drive activity, in particular rotary drive activity, and not for this purpose a force-dependent variable, e.g. B. a torque in the power flow of the rotary drive. As soon as. B. a certain, still permissible for the hand-held machine tool pivoting movement, for. B. is exceeded in the order of 10 _° in a maximum time, the clutch is disengaged and the drive activity is interrupted. It does not matter how firmly the user holds the hand tool and how stable he is. Independently of this, due to the method according to the invention, reliable care is taken to ensure that inadmissible pivoting movements of the hand-held power tool and the hand holding it are prevented with all the known impairments and damage resulting therefrom.

Of course, the advantages achieved by means of claims 3, 4 or 5 can also be achieved together with the means of claim 1.

Advantageous further developments and improvements of the method specified in the main claim are possible due to the features contained in the further claims.

The invention further relates to a hand tool with the features in the preamble of claim 11. According to the invention, such a hand tool is characterized by the features in the characterizing part of claim 11. Advantageous further developments and improvements of such a handheld power tool result from the features in claims 12-29. The handheld power tool designed in this way is relatively simple in construction and inexpensive. Since it has the advantages explained at the outset, this justifies the overall little additional effort, also with regard to the reliable safety achieved and easier handling for the user.

drawing

The invention is explained in more detail below with reference to exemplary embodiments shown in the drawings.

• Fig.1 1 einen schematischen, teilweisen axialen Längsschnitt einer Handwerkzeugmaschine, bei dem vereinfacht nur einige wichtige Teile des Antriebsstranges gezeigt sind,
• Fig. 2 ein vereinfachtes schematisches Funktionsbild,
• Fig. 3 eine schematische Darstellung des Translationsweges eines mittels der Handwerkzeugmaschine gemäß Fig. 1 angetriebenen Werkzeuges,
• Fig. 4 ein vereinfachtes schematisches Funktionsbild.
• Fig. 5 einen schematischen, teilweisen axialen Längsschnitt einer Handwerkzeugmaschine, bei dem vereinfacht nur einige wichtige Teile des Antriebsstranges gezeigt sind,
• Fig. 6 und 7 jeweils vereinfachte schematische Funktionsbilder verschiedener Betriebsweisen der Handwerkzeugmaschine in Fig. 1,
• Fig. 8 eine schematische Seitenansicht einer Schaltkupplung im ausgerückten Zustand,
• Fig. 9 und 10 eine schematische Seitenansicht bzw. Vorderansicht der Schaltkupplung im eingerückten Zustand,
• Fig. 11 und 12 zwei weitere Ausführungsbeispiele einer Handwerkzeugmaschine gem. Fig. 1.

Show it:

• 11 shows a schematic, partial axial longitudinal section of a hand power tool, in which only a few important parts of the drive train are shown in simplified form,
• 2 shows a simplified schematic functional diagram,
• 3 shows a schematic illustration of the translation path of a tool driven by means of the handheld power tool according to FIG. 1,
• Fig. 4 is a simplified schematic functional diagram.
• Fig. 5 3 shows a schematic, partial axial longitudinal section of a hand tool, in which only a few important parts of the drive train are shown in simplified form,
• 6 and 7 each simplified schematic functional diagrams of different modes of operation of the hand machine tool in Fig. 1,
• 8 is a schematic side view of a clutch in the disengaged state,
• 9 and 10 is a schematic side view and front view of the clutch in the engaged state,
• 11 and 12 two further embodiments of a hand tool according to. Fig. 1.

Description of the invention

In Fig. 1, a hand tool is shown schematically, which here consists of a hammer drill or which can instead consist of a pure hammer for chisel operation. Such hammers are generally known (DE-AS 12 06 817). The hammer drill shown has a housing 10 in which an electric drive motor 11, which is designed as a universal motor, a gear 12 and a striking mechanism 13 are also arranged. In this respect, the hammer drill is e.g. designed in accordance with DE-OS 28 20 128, to which express reference is made here, so that particular details of the transmission 12 and the striking mechanism 13 need not be explained in detail.

The drive motor 11 carries on the motor shaft 14 a motor pinion 15 which is in engagement with a gear 16 which is held on a shaft 17 in a rotationally fixed manner. On the shaft 17 there is a drum 18 as part of a striking mechanism 13, the driver pin 19 of which engages with play in a transverse bore of a pivot pin 20, which in turn is supported in a fork-shaped end of a drive piston 21. The drive piston 21 is designed as a hollow piston and acts via an air cushion on a striker 22 movably mounted therein. The drive piston 21 of the striking mechanism 13, which is driven axially to and fro via the drum 18, drives the striker 22 via the air cushion, which strikes its impact energy e.g. via a striker not shown or directly to a tool 24 inserted into a tool holder 23. The tool 24 is e.g. from a drill. Other types of tools can also be accommodated in the tool holder 23.

The tool 24 can be driven in rotation by means of a rotating sleeve 25 of the transmission 12, which is only indicated schematically. For this purpose, the rotary sleeve 25 carries a gear 26 which is non-rotatable thereon and which is in engagement with a pinion 27 which is non-rotatably or coupled to the shaft 17 via a special safety coupling. Such a safety clutch in one embodiment is e.g. described in DE-OS 28 20 128, to which reference can be made here.

A special clutch 28 is arranged in the drive train from the engine 11 to the tool 24, which is shown only schematically here. This clutch is arranged in the rotary drive drive train in front of the branch of the striking mechanism 13. It is namely in the embodiment shown between the gear part 15 driven by the motor pinion 15 in the form of the gear 16 and the shaft 17 on the one hand and the gear train driving the striking mechanism 13 on the other hand, to which the shaft 17 e.g. rotatable drum 18 and the driven parts of the striking mechanism 13, which are explained at the beginning.

In another embodiment, not shown, the coupling 28 is instead behind the branch shown, where it is arranged in the pure percussion drive branch, e.g. between the shaft 17 on the one hand and the drum 18 on the other hand, so that when the clutch 28 is disengaged, the drive of the drum 18 is interrupted and the striking mechanism 13 stands still, even if the rotary drive which is still driven and rotating shaft 17 above is not interrupted, but is still effective.

The clutch 28 is automatically disengaged depending on a size with an interruption of the driving activity of at least the striking mechanism 13. In this case, the gear complex adjoining the clutch 28 in FIG. 1 is not driven, so that in this case, in addition to the striking mechanism 13, which stands still, then also the drive rotating the rotating sleeve 25 and the tool 24 also stands still. If the clutch 28 is instead arranged between the shaft 17 and the drum 18, only the striking mechanism 13 stands still when the clutch 28 is disengaged. The clutch 28 is designed here as a clutch. It consists in particular of a non-positive clutch, e.g. from a friction clutch. The clutch 28 is designed as a servo clutch, which uses the existing energy diverted from the drive motor 11, e.g. is controllable by means of electrical or electromechanical energy.

In another embodiment, the coupling 28 may also be a form-fitting one Be designed clutch, for example as a claw clutch. Then the clutch 28 should be arranged in front of the branch of the striking mechanism 13 and as shown in FIG. 1, so that when the clutch is disengaged, the rotary drive is also stopped in addition to the striking mechanism 13. Furthermore, it is recommended that the drive motor 11 is then also switched off and stopped when the clutch 28 is disengaged so that the clutch 28 can be re-engaged later when the clutch 28 is disengaged.

As is only hinted at in the drawings in connection with the clutch 28 shown, it has at least one disengaged release spring 29 which is biased and locked in the engaged state and which disengages automatically when the clutch 28 is disengaged. When the clutch 28 is actuated, the release spring 29 can be tensioned and locked again. Thus, the force to separate the two halves of the clutch 28 from the release spring 29 is supplied.

The handheld power tool also contains a sensor 30, which is only indicated schematically and which is fixedly arranged in the interior of the housing 10. The sensor 30 is designed in particular as an electrical sensor. However, it can also be designed as a mechanical or electromechanical sensor instead. The sensor 30 is in operative connection with the clutch 28 and acts on the clutch 28 as soon as it responds. In the exemplary embodiment shown, the sensor 30 is designed as an idle sensor, which detects as a quantity the position of the tool 24 or a part of the striking mechanism 13 that is in the idle distance (FIG. 3) and which is moved in translation, and then acts on the clutch 28 for automatic disengagement. Furthermore, the idle sensor is able to automatically detect the leaving of this path position in the direction of the striking position and then to apply the clutch 28 for automatic re-engagement. In the embodiment shown, in which the clutch 28 is located in front of the branch of the striking mechanism 13 in the drive train, not only the striking mechanism 13 is stopped when the clutch 28 is disengaged, so that the tool 24 is in the front region, namely the idling region, of its translation path, but the rotary drive is also switched off at the same time, so that the tool 24 does not rotate about the rotary drive axis 31.

In the embodiment shown, the sensor 30 is e.g. designed as an electrical limit switch. In addition, a control device 34, e.g. a switching logic, with which the sensor 30 is connected, wherein the sensor 30 can activate the control device 34 when activated. The sensor 30 can e.g. be designed as an electromagnetic sensor which activates the control device 34 when said path position is reached. The control device 34 is in turn in operative connection with the clutch 28 for disengaging and reinserting it (FIGS. 2, 4). If the sensor 30 responds, the control device 34 is activated, which in turn controls the clutch 28 electrically or electromechanically, e.g. electromagnetic, disengages. As soon as the tool 24 or a translationally reciprocating part of the striking mechanism 13, which is monitored by the sensor 30, is shifted from the idle position in FIG. 3 to the right on the translation path into the region of a striking position, this is detected by the sensor 30 and in addition, the control device 34 is also activated, which now controls the clutch 28 in the sense of re-engagement.

With the hand-held power tool designed in this way, it is possible for the sensor 30 to be used as a variable to detect reaching a position on the idle path of the tool 24 or a translationally moving part of the striking mechanism 13 and when this position is reached the clutch 28 is automatically disengaged and at Leaving this path position, the clutch 28 is automatically engaged again. This is illustrated with reference to FIG. 3. The overall translation path of the tool 24 - or for example the reciprocatingly driven drive piston 21 - during impact operation corresponds to a distance of considerable length, which can only be approximately 22 mm, for example. When the striking mechanism 13 is switched on, the tool 24 is in the striking mode in a striking position shifted to the right on this route in FIG. Due to the acting impacts, the tool 24 executes an oscillating movement which is carried out over a distance of 1/3 of the total translation path. The sensor 30 is e.g. B. not placed in this area, but, seen in Figure 3 from right to left, at least in the second or better still in the third third and thus on an area that the tool 24 or a reciprocatingly driven part of the striking mechanism 13th only reached in idle position. The sensor 30 is placed on this idle line, for example, so that it is passed by the tool 24 going into the idle position and in the idle position the end of the tool 24 is on the left and at a distance from the sensor 30, so that the sensor 30 uses this as a criterion for idle operation and the application of clutch 28 to disengage. Then the sensor 30 could, for example, in the middle third of the translation path of the tool 24 or also be placed further to the right of it. It depends on the design of the sensor 30 where it is ultimately located. If the sensor 30 responds when the tool is, for example, in overlap with it, the sensor 30 is reliably placed at a suitable point on the idling path, for example in the last third, as shown by solid lines in FIG. 3. If the sensor 30 responds when it has been overrun by the tool 24 and there is no overlap with it in the idle position, the sensor 30 can be arranged, for example, in the middle position, as indicated by dashed lines in FIG. 3.

In all of this, the main idea is that the idling position of the tool 24 or a reciprocating part of the striking mechanism 13 is detected by the sensor 30 during impact operation and the clutch 28 is then actuated so that it disengages. As soon as the tool 24 or said part of the striking mechanism 13 is moved from this idling position to the right into the striking position by movement in FIGS. 1, 3, this is also detected by the sensor 30 and the clutch 28 is acted upon to re-engage. For everything, it does not depend on any force to be exerted by the user of the hand-held power tool in order to achieve the engagement of the clutch for the impact operation and the disengagement of the clutch automatically when idling. Rather, a reliable and high-quality idle shutdown is created, which does not require any additional operating or engagement forces from the user. Special idling devices or catching devices or the like are therefore unnecessary in such hand-held power tools. Another advantage is that almost any short idle paths are possible that can be used.

In FIG. 2 and in particular 4 it is indicated how the sensor 30 acts indirectly on the clutch 28. If the sensor 30 responds when the idling position has been reached, the sensor 30 activates the control device 34, in particular switching logic, which in turn then sends a control pulse in the sense of disengaging the clutch to an electromechanical, e.g. electric actuator, in particular disengaging actuator 35, which then engages the clutch 28 to disengage it. If after this the tool 24 has been shifted from the idling position to the striking position, the clutch 28 is also engaged again by the sensor 30 via the control device 34, which in turn then generates a control pulse e.g. leads to an actuator in the form of an engagement actuator 36 which engages the clutch 28 to engage it. Like the disengaging actuator 35, the engaging actuator 36 can be controlled by the control device 34 e.g. be operated electromechanically, in particular electromagnetically.

In the following description of FIGS. 5 to 10, the same parts have the same reference numbers as in the preceding description.

In Fig. 5, a hand tool is shown schematically, which here consists of a hammer drill. The hammer drill has a housing 10 in which an electric drive motor 11, which is designed as a universal motor, a gear 12 and a striking mechanism 13 are arranged. In this respect, the hammer drill is e.g. designed in accordance with DE-OS 28 20 128, to which express reference is made here, so that special details of the transmission 12 and the striking mechanism 13 need not be explained.

The drive motor 11 carries on the motor shaft 14 a motor pinion 15 which is in engagement with a gear 16 which is held on a shaft 17 in a rotationally fixed manner. On the shaft 17 there is a drum 18 as part of the striking mechanism 13, the driver pin 19 of which is fixed and engages with play in a transverse bore of a pivot pin 20 which in turn is supported in a fork-shaped end of a drive piston 21. The drive piston 21 is designed as a hollow piston and acts via an air cushion on a striker 22 movably mounted therein. The drive piston 21 of the striking mechanism 13, driven axially back and forth via the drum 18, drives the striker 22 via the air cushion, which directly applies its impact energy to the striker 22 releases tool 24 inserted into a tool holder 23. The tool 24 is e.g. from a drill. Other types of tools can also be accommodated in the tool holder 23.

The tool 24 can be driven in rotation by means of a rotating sleeve 25 of the transmission 12, which is only indicated schematically. For this purpose, the rotary sleeve 25 carries a gear 26 which is non-rotatable thereon and which is in engagement with a pinion 27 which is non-rotatably or coupled to the shaft 17 via a special safety coupling. Such a safety clutch is also described in DE-OS 28 20 128 to which reference is made.

A special coupling 28 is arranged in the drive train from the drive motor 11 to the tool 14, which is only shown schematically here. This clutch 28 is arranged in the rotary drive drive train in front of the branch of the striking mechanism 13. It is namely between the gear part driven by the motor pinion 15 in the form of the gear wheel 16 and the shaft 17 on the one hand and the gear train driving the striking mechanism 13 on the other hand, in the form of the drum 18 which is rotationally fixed to the shaft 17 and the parts of the striking mechanism 13 driven thereby, such as is explained at the beginning.

In another embodiment, not shown, the clutch 28 is located behind the branch shown in the pure rotary drive branch, e.g. on the shaft 17 or between the pinion 27 and its drive from the shaft 17th

The clutch 28 is automatically disengaged depending on an overload size with an interruption of the drive activity. In this case, the gearbox complex adjoining it on the left in FIG. 5 is not driven, so that in this case both the striking mechanism 13 is stationary and the drive rotating the rotating sleeve 25 and the tool 24. The clutch 28 is designed as a clutch. This can e.g. be designed as a positive coupling, in this case e.g. as a claw coupling. Then it is advisable to also switch off and stop the drive motor 11 when this clutch 28 is disengaged, so that later when the clutch 28 is re-engaged, the disengagement can take place in a manner described above. Instead, the clutch 28 can, as shown, be designed as a non-positive clutch, e.g. as a friction clutch. The clutch 28 is designed as a servo clutch, which by means of the existing energy diverted from the drive motor 11, e.g. is controllable by means of electrical or electro-mechanical energy.

5 to 10 in connection with the clutch 28 shown, it has at least one disengaged release spring 29 which is biased in the engaged state and which disengages the clutch clutch 28 automatically when the clutch 28 is released.

When the clutch 28 is actuated, the release spring 29 can be tensioned and locked again. Thus, the force to separate the two halves of the clutch 28 from the release spring 29 is supplied.

The hand-held power tool also has a sensor 130, which is only indicated schematically and is fixedly connected to the housing 10, and is expediently located in the interior of the housing 10. The sensor 130 is designed as an electrical or mechanical or electromechanical sensor. The sensor 130 is operatively connected to the clutch 28 (Fig. 6-10) and acts on the clutch 28 when a movement size of the hand-held hand tool is exceeded. In the exemplary embodiment shown, the sensor 130 is designed as a rotation sensor which, as a movement variable, detects the path and / or the speed and / or the acceleration of an external swiveling movement of the hand-held hand-held power tool in space around a rotary drive axis 31 of the driven tool 24.

The hand-held power tool also has an engagement adjuster 32 which can be reached from the outside of the machine, in particular manually operated, and which, e.g. consists of an operating button. If the clutch 28 has been disengaged, it can be re-engaged directly or indirectly and mechanically, electrically or electromagnetically by means of the engagement actuator 32.

In the exemplary embodiment shown in FIGS. 8-10, the sensor 130 is designed as a mechanical inertia switch and mechanically coupled to the clutch 28 to disengage it via an indicated lever 33. The lever 33 bearing the sensor 30 at the end is held freely pivotable in the housing 10 about a schematically indicated pivot axis 38, which runs approximately parallel to the central axis of the clutch 28, an approximately U-shaped claw at the end of the lever 33 being so dimensioned and is designed so that it can hold the clutch 28 in the engaged state according to FIGS. 9 and 10 in this engaged state. The claw is e.g. Approximately radially from the outside to both compressed clutch halves which are jointly overlapped by the claw so that the release spring 29 remains in the compressed state and the clutch 28 cannot disengage. 10, the direction of rotation of the tool 24 is symbolized schematically by arrow 41. If the tool 24 e.g. blocked in the rock, the handheld power tool is hurled around in the direction of arrow 40. The sensor 30 responds, which in this embodiment, as a mechanical inertia switch, together with the lever 33 and the claw engaging on the clutch 28 is pivoted about the pivot axis 38 in the direction of arrow 39 and so that the claw at the end of the lever 33 both coupling halves releases the clutch 28 so that the compressed release spring 29 can automatically move the clutch 28 into the disengaged position shown in FIG. 8.

FIG. 8 schematically shows an engagement actuator 32, which is mechanically coupled to the clutch 28 to engage it via its own lever 37. If the clutch 28 is to be engaged again, starting from the disengaged position according to FIG. 8, the engagement actuator 32 is pressed, which mechanically pushes the left half in FIG. 8 by pressing the release spring 29 against the right clutch half via the lever 37, until the engaged position according to FIG. 9 is reached, in which the claw at the end of the lever 33 then automatically engages over both compressed coupling halves of the clutch 28.

In the embodiment shown in Figs. 6 and 7, a control device 34, e.g. a switching logic, with which both the sensor 130 and the engagement actuator 32 are connected, each of which can activate the control device when it becomes effective. In this case, the sensor 130 is designed as an electromechanical sensor, which activates the control device 34 in the event of an overload. The control device 34 is in turn in operative connection with the clutch 28 for disengaging and reinserting it (FIGS. 6, 7). If the sensor 130 responds, the control device 34 is activated, which in turn controls the clutch 28 electrically or electromechanically, e.g. electromagnetic, disengages. If the engagement actuator 32 is then actuated from the outside and there is no overload, the actuation of the engagement actuator 32 likewise activates the control device 34, which now controls the clutch 28 in the sense of re-engagement.

With the hand-held power tool designed in this way, it is possible that a movement variable of the hand-held hand-held power tool in space is detected as an overload variable via the sensor 130 and the clutch 28 is automatically disengaged when a predetermined value of this movement variable is exceeded. In this case, the sensor 130 can be designed such that it detects, as a movement variable, a path that the hand-held power tool traverses. One possible path is, for example, the swivel angle of a swivel movement of the hand-held power tool about the rotary drive axis 31, the rotation sensor 30 then responding, for example when a permissible swivel movement of, for example, 10 ° swivel angle is exceeded and disengaging the clutch 28 in the manner described. Instead of this or also additionally, the speed and / or acceleration with which the hand-held power tool moves in space can also be detected as a movement variable by means of the sensor 130. The main idea here is to use the rotation of the housing 10 of the hand-held power tool when the driven tool 24 is blocked - in other words, it receives an angular momentum - as a signal for switching off the rotary drive when the movement quantity is exceeded by disengaging the clutch 28. Then the rotary drive is interrupted so that the rotary actuation of the tool 24 stops, while the drive part located in FIG. 5 to the right of the clutch 28, in particular the drive motor 11 with gear 15, 16, can continue to rotate freely. Only if the clutch 28 is designed as a positive clutch, it is advisable to disconnect and switch off the drive motor 11 from the mains at the same time as the clutch 28 is disengaged. For everything, it is irrelevant how firmly the user holds the hand tool and how stable he is. Irrespective of this, the overload device explained ensures that inadmissible twisting of the hand-held power tool and thus the hand of the user holding it with the risk of injuries associated with it are prevented. The safety guaranteed by the overload device is always reliable, regardless of the working torque of the hand tool that the user applies with the holding torque. The user therefore does not need to have a holding moment that is far too large for most of the time in anticipation of a possible blocking. Rather, he can work loosely and relaxed with much less effort and thus concentrate better on the actual machining process. Thus, with the aid of the overload device with simple, inexpensive means, protection of the person working with the hand tool against injuries by hurling the hand tool when the rotating tool 24 is blocked, in particular protection against hurling the hand tool, for example when the tool 24 is in the workpiece, eg in stone, concrete or the like, should get caught. The path and / or the speed and / or the acceleration of an external swiveling movement of the hand-held power tool about the rotary drive axis 31 is thus recorded as the movement variable. If this movement quantity exceeds a predetermined value, this is detected by sensor 30, which then disengages clutch 28 directly (FIGS. 8-10 or indirectly (FIGS. 6, 7). When actuated directly, clutch 28 is disengaged mechanically the lever 33. In the case of indirect actuation, the sensor 130 activates the control device 34, in particular switching logic, when the predetermined value of the movement quantity is exceeded, which in turn then generates a control pulse in the sense of disengaging the clutch on an electromechanical, for example electrical, actuator, in particular disengaging actuator 35 , which then engages the clutch 28 to disengage it. If, after this, the value of the movement quantity which caused the clutch 28 to disengage has been undershot, the clutch 28 is re-engaged, for example by manually pressing in the engagement adjuster 32, which is then directly or indirectly and mechan isch, electrically or electromechanically causes the clutch 28 to be re-engaged. In the exemplary embodiment according to FIGS. 8-10, the clutch 28 is immediately and mechanically re-engaged by means of the engagement actuator 32 6 and 7, on the other hand, the control device 34, in particular switching logic, is activated by, for example, manually pressing in the engagement actuator 32, which then in turn leads to a control pulse, for example on an actuator in the form of an engagement actuator 36, which is connected to the clutch 28 attacks to engage them. The engagement actuator 36 is actuated by the control device 34, for example electromechanically, in particular electromagnetically.

It is clear that the two embodiments of the basic idea of interrupting the drive activity of the hand-held power tool when the quantities measured by electrical means are exceeded and which are illustrated and described in FIGS. 1 to 4 and 5 or 10 are also very advantageous on a single machine can be used. A synergy effect then also results here, since the electronics processing the measured electrical signals are of course smaller than the sum of those of the two embodiments.

FIGS. 11 and 12 show two further exemplary embodiments of the invention. FIG. 11 shows a hammer drill in which the clutch 28 is arranged behind the striking mechanism. In addition, there is a holding device 50 in the drive train between the coupling 28 and the tool 24, via which the named drive train can be connected to the housing 10 of the hammer drill. The holding device 50 is designed as a known, electrically triggerable brake.

If the clutch 28 is released in the manner described above, only the drive train for rotating the tool is interrupted.

The brake 50, which is actuated at the same time, ultimately firmly connects the housing of the rotary hammer to the tool 24. As a result, the angular momentum, which was given, for example, when the drilling tool 24 was blocked in the workpiece in the housing 10 and which led to the release of the clutch 28, can be caught. Injuries to the operator by the described angular momentum are thus reliably avoided.

In the exemplary embodiment of the invention described in FIG. 12, the clutch 28 and the holding device (brake 50) are already in the drive train between the motor 11 and the striking mechanism. In this exemplary embodiment, in addition to the rotary drive, the striking mechanism is also stopped when the clutch 28 is triggered.

Claims (29)

1. Method for interrupting the percussion-drive activity of a hand-operated machine tool in the drive train from its drive motor (11) to its percussion- and/or rotary-drivable tool (24), in which a coupling (28) arranged in the drive train is disengaged automatically when a predetermined quantity recorded by a sensor (30) is reached, the quantity being independent of the user's holding force and reproducing a movement quantity of one of the parts of the hand-operated machine tool moved in translational motion or of the tool (24), characterised in that the path position of a percussion-mechanism part or of the tool (24) is detected as a movement quantity, and the coupling (28) is re-engaged automatically when this path position is left, and in that, when this path position is reached, the sensor (30) activates a control device (34), especially a logical switching unit, which itself transmits a control pulse to an especially electromechanical, for example electromagnetic, actuating drive (35), especially disengagement actuating drive, which acts on the coupling (28) to disengage it.

2. Method according to Claim 1, characterised in that the sensor (30) activates the control device (34), especially the logical switching unit, when departing from the path position in the direction of the percussion position, and the control device (34) itself transmits a control pulse to an especially electromechanical, for example electromagnetic, actuating drive (36), especially engagement actuating drive, which acts on the coupling (28) to engage it.

3. Method for interrupting the rotary-drive activity of a hand-operated machine tool in the drive train from its drive motor (11) to its percussion- and/or rotary-drivable tool (24), in which a coupling arranged in the drive train is disengaged automatically in dependence on a (sic) when a predetermined quantity recorded by a sensor (30) is reached, the quantity being independent of the user's holding force and reproducing a movement quantity of the hand-operated machine tool as a whole or of one of its co-moved parts, characterised in that a path which the hand-operated machine tool covers is detected as a movement quantity.

4. Method for interrupting the rotary-drive activity of a hand-operated machine tool in the drive train from its drive motor (11) to its percussion- and/or rotary-drivable tool (24), in which a coupling arranged in the drive train is disengaged automatically in dependence on a (sic) when a predetermined quantity recorded by a sensor (30) is reached, the quantity being independent of the user's holding force and reproducing a movement quantity of the hand-operated machine tool as a whole or of one of its co-moved parts, characterised in that the speed with which the manually controlled hand-operated machine tool moves in space is detected as a movement quantity.

5. Method for interrupting the rotary-drive activity of a hand-operated machine tool in the drive train from its drive motor (11) to its percussion- and/or rotary-drivable tool (24), in which a coupling arranged in the drive train is disengaged automatically in dependence on a (sic) when a predetermined quantity recorded by a sensor (30) is reached, the quantity being independent of the user's holding force and reproducing a movement quantity of the hand-operated machine tool as a whole or of one of its co-moved parts, characterised in that the acceleration with which the hand-operated machine tool moves in space is detected as a movement quantity.

6. Method according to one of the preceding claims, characterised in that the sensor (30) disengages the coupling (28) directly and mechanically when the predetermined value of the movement quantity is exceeded.

7. Method according to one of the preceding Claims 3 to 5, characterised in that, when the predetermined value of the movement quantity is exceeded, the sensor (30) activates a control device (34), especially a logical switching unit, which itself transmits a control pulse to an especially electromechanical, for example electromagnetic, actuating drive (35), especially disengagement actuating drive, which acts on the coupling (28) to disengage it.

8. Method according to one of the preceding claims, characterised in that, after the disengagement of the coupling (28) and after the value of the movement quantity has fallen below the predetermined value, the coupling (28) can, if required, be engaged directly or indirectly and mechanically, electrically or electromagnetically, especially by the manual actuation of an engagement actuator (32).

9. Method according to Claim 8, characterised in that the engagement actuator (32) engages the coupling (28) directly and mechanically.

10. Method according to Claim 9, characterised in that the engagement actuator (32), when actuated, activates the control device (34), especially logical switching unit, which itself transmits a control pulse to an especially electromechanical, for example electromagnetic, actuating drive (36), especially engagement actuating drive, which acts on the coupling (28) to engage it.

11. Hand-operated machine tool, especially hammer drill, in the drive train from the drive motor (11) to the driven tool (24) of which is arranged a coupling which can be disengaged automatically in dependence on a measured quantity in order to interrupt the percussion-drive activity, especially for carrying out the method according to Claim 1, characterised in that the coupling is designed as a positive or non-positive coupling (28), and in that there is arranged in, preferably firmly connected to, the hand-operated machine tool especially an electrical, mechanical or electromechanical sensor (30) which, in the percussion mode, detects the idling position and which is connected operatively to the shift coupling (28) and loads the latter for automatic disengagement when the measured quantity is exceeded.

12. Hand-operated machine tool, especially hammer drill, in the drive train from the drive motor (11) to the driven tool (24) of which is arranged a coupling which can be disengaged automatically in dependence on a measured quantity in order to interrupt the rotary-drive activity, especially for carrying out the method according to Claims 3, 4 or 5, characterised in that the coupling is designed as a positive or non-positive coupling (28), and in that there is arranged in, preferably firmly connected to, the hand-operated machine tool especially an electrical, mechanical or electromechanical sensor (30) which is connected operatively to the shift coupling (28), in that the coupling is a wrap- spring coupling which can be actuated electromagnetically when the quantity is exceeded, and the sensor (30) loads the coupling (28) for automatic disengagement when the measured quantity is exceeded.

13. Hand-operated machine tool according to Claim 11 or 12, characterised in that the sensor (30) is designed as a limit switch.

14. Hand-operated machine tool according to one of Claims 11 to 13, characterised in that the sensor (30) is designed as an electromechanical feeler which is connected operatively inside the hand-operated machine tool to a control device (34), especially logical switching unit, and which activates the latter when the path position is reached, and in that the control device (34) is connected operatively to the shift coupling (28) for the disengagement and re-engagement of the latter.

15. Hand-operated machine tool according to one of Claims 11 to 14, characterised in that the shift coupling (28) is designed as a servo shift coupling and can be actuated by means of electrical or electromechanical energy branched off from the drive motor (11) of the hand-operated machine tool.

16. Hand-operated machine tool according to one of Claims 11 to 15, characterised by an electromechanical, especially electromagnetic, actuating drive, especially disengagement actuating drive (35) and/or engagement actuating drive (36), of the shift coupling (28), which drive can be loaded by the control device (34).

17. Hand-operated machine tool according to one of Claims 11 to 16, characterised in that the shift coupling (28) has at least one disengagement spring (29) which is pretensioned and locked in the engaged state and which, during the disengaging actuation of the shift coupling (28), disengages the latter automatically by relaxing and can be tensioned and locked again during the engaging actuation of the shift coupling (28).

18. Hand-operated machine tool according to one of Claims 11 to 17, characterised in that the shift coupling (28) is arranged in the percussion-mechanism drive train or especially in the rotary-drive train, preferably in front of its branch-off to the percussion drive, of the hammer drill.

19. Hand-operated machine tool according to Claim 18, characterised in that the shift coupling (28) is arranged in the drive train between the output-side gear (16, 17) driven by the motor pinion (15), on the one hand, and the gear train driving the percussion mechanism (13), on the other hand.

20. Hand-operated machine tool according to Claim 12, characterised in that the sensor (30) is designed as a rotation sensor which detects as a movement quantity the path and/or speed and/or acceleration of an external pivoting movement of the manually controlled hand-operated machine tool in space about a rotary-drive axis (31) of the driven tool (24).

21. Hand-operated machine tool according to Claim 20, characterised in that the sensor (30) is designed as a mechanical inertia switch.

22. Hand-operated machine tool according to Claim 21, characterised in that the mechanical inertia switch is coupled mechanically, via a lever (33), to the shift coupling (28) for the disengagement of the latter and acts thereon.

23. Hand-operated machine tool according to one of Claims 12, 14, 20, 21 or 22, characterised by an especially manually actuable engagement actuator (32) which can be reached from outside the machine and by means of which the shift coupling (28) can be re-engaged directly or indirectly and mechanically, electrically or electromechanically.

24. Hand-operated machine tool according to Claim 23, characterised in that the engagement actuator (32) is coupled mechanically, via a lever (37), to the shift coupling (28) for the engagement of the latter and acts thereon.

25. Hand-operated machine tool according to Claim 23, characterised in that the engagement actuator (32) is connected to the control device (34), especially logical switching unit, and, when actuated, activates the latter.

26. Hand-operated machine tool according to one of Claims 12, 17, 20 to 25, characterised in that the shift coupling (28) is arranged in the rotary-drive train in front of or after its branch-off to the switching drive of the hammer drill.

27. Hand-operated machine tool according to Claim 26, characterised in that the shift coupling (28) is arranged in the drive train between, on the one hand, the output-side gear (16, 17) driven by the motor pinion (15) and, on the other hand, the gear train driving the percussion mechanism (13).

28. Hand-operated machine tool according to one of the preceding claims, characterised in that the drive train between coupling (28) and tool (24) can be connected to the housing (10) of the hand-operated machine tool by means of a holding device (50), especially a brake, when the drive train to the motor (11) is interrupted by means of the coupling (28).

29. Hand-operated machine tool according to Claim 28, characterised in that the holding device (50) connects the drive train for the rotation of the tool (24) and/or to the percussion mechanism (13) to the housing of the hand-operated machine tool.

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