Handheld power tool device

This application is based on German Patent Application 10 2009 046 789.0 filed on Nov. 17, 2009.

1. Field of the Invention

The invention is based on a handheld power tool device.

2. Description of the Prior Art

From German Patent Disclosure DE 100 41 632 A1, a handheld power tool device with at least one safety mechanism, which intervenes in an uncontrolled blocking situation and which has a sensor unit, has already been proposed.

The invention is based on a handheld power tool device with at least one safety mechanism, which intervenes in an uncontrolled blocking situation and which has a sensor unit.

It is proposed that the sensor unit is provided for directly detecting at least one orientation parameter. The term “safety mechanism” should be understood in particular to mean a device which in at least one operating state prevents damage, particularly to a part of the handheld power tool, and/or in particular enhances safety for a user. The term “uncontrolled blocking situation” should be understood in particular to mean a process in which a tool insert seizes in a workpiece that is to be machined, and the reaction torque exerted on the housing exceeds a holding force of the user, and the housing rotates uncontrollably over a defined angular range about an axis, in particular an axis of rotation of a tool insert fastener. The term “intervene” should be understood in particular to mean that the safety mechanism, in an uncontrolled blocking situation, takes measures which enhance safety, such as in particular the measure of shutting off a drive motor. The term “sensor unit” should be understood in particular to mean a sensor unit appearing useful to one skilled in the art, in particular one that measures a magnetic field and/or some other field, such as a fluxgate magnetometer unit, a gravity sensor unit, and/or in particular a Hall sensor unit. The term “provided” should in particular be understood to mean especially equipped, designed, and/or programmed. The term “orientation parameter” should be understood in particular to mean a parameter which is variously pronounced at different orientations of the handheld power tool, in particular at different orientations of the handheld power tool about an axis of rotation of a tool insert fastener, preferably even when the handheld power tool is not in motion. Preferably, the at least one orientation parameter is at least one component of a field that can be described by a vector. The term “detects” should be understood in particular to mean that in a measurement operation, the sensor unit measures the orientation parameter and converts its value into an electrical sensor parameter. The term “sensor parameter” should be understood in particular to mean a parameter which describes at least the orientation parameter. Advantageously, the sensor unit transmits the sensor parameter in digital form. Especially advantageously, the sensor unit transmits two or three sensor parameters serially in digital form. Alternatively or in addition, the sensor unit could transmit two or three sensor parameters in parallel and/or in particular in analog fashion. The phrase “directly detect” should be understood in particular to mean that the sensor unit is provided for measuring an orientation parameter that is directly dependent on an orientation of the handheld power tool; that is, in particular, the orientation need not be calculated by integration. In addition to the aforementioned directly detecting sensor unit, the safety mechanism could have an acceleration sensor, which detects the orientation indirectly and detects an acceleration about an axis of rotation of a tool insert fastener. As a result of the embodiment according to the invention of the handheld power tool device, especially great safety can be attained, particularly even in the presence of heavy vibration and in the event of a slow rotation of the handheld power tool, which causes a slight acceleration.

In a further feature, it is proposed that in at least one operating state, the sensor unit detects an orientation parameter of the Earth's magnetic field, and as a result, in a convenient and structurally simple way, an orientation can be determined especially advantageously. The term “Earth's magnetic field” should be understood in particular to mean a magnetic field generated by kinetic energy of the core of the Earth. Alternatively or advantageously in addition, the handheld power tool device could have a sensor unit which in at least one operating state detects at least one orientation parameter of the field of gravity of the Earth, as a result of which great safety can be achieved especially reliably.

It is furthermore proposed that the sensor unit is provided for detecting at least two different orientation parameters, which describe an orientation, and as a result, especially precise detection of the orientation, in a manner that sturdily withstands interference, is possible. The term “different orientation parameters” should be understood in particular to mean different components of the field that can be described by a vector. Preferably, the sensor unit detects three different orientation parameters. Also preferably, the sensor unit detects different orientation parameters, whose components of the vector are oriented essentially perpendicular to one another; in particular, “essentially” means with a deviation of less than 30° and advantageously less than 10°. Advantageously, the orientation parameter describes an orientation of at least the handheld power tool relative to the Earth's magnetic field.

It is also proposed that the safety mechanism has a computation unit, which is provided for comparing at least two orientation parameters measured at staggered times. The term “computation unit” should be understood in particular to mean a unit with an information input, information processing, and an information output. Advantageously, the computation unit has at least one processor, a memory, a communication device, optionally further electrical components, an operating program, and/or calculation routines, which are disposed all on the same board, divided up into a plurality of structural groups, and/or advantageously disposed in a common housing. Preferably, the computation unit calculates a value from the two orientation parameters measured at staggered times and advantageously, in particular by differentiation, it calculates the speed of a change in orientation. The term “measured orientation parameter” should be understood in particular to mean a sensor parameter, that is, an output variable of the sensor unit. As a result of the comparison made by the computation unit, great safety in various work situations can be conveniently achieved; in particular, even a slow rotation, and especially advantageously an incremental rotation, can be securely detected.

It is furthermore proposed that the safety mechanism has a computation unit which is provided for comparing a change in orientation with a shutoff threshold value, as a result of which especially great safety can be achieved. The term “change in orientation” should be understood in particular to mean a piece of information which results from a comparison of two measured orientation parameters. Advantageously, the shutoff threshold value is adjustable by a user. Preferably, a single computation unit compares the measured orientation parameters with one another and compares the resultant change in orientation with the shutoff threshold value. Alternatively, two spatially separated computation units could perform the two different comparisons.

It is also proposed that the sensor unit is spaced apart from components which essentially influence detection of the Earth's magnetic field; as a result, interfering factors on detecting the Earth's magnetic field can be reduced, and thus especially reliable detection of the orientation can be achieved. The term “a component essentially influencing detection of the Earth's magnetic field” should be understood in particular to mean a component which, by superimposing interference fields on the Earth's magnetic field, varies at least one orientation parameter, measured by the sensor unit at a spacing of more than 1 cm from the component, of the Earth's magnetic field by more than 10%, and in particular by more than 25%. The term “spaced apart” should be understood in this connection to mean in particular that each point of the sensor unit is at a distance of at least 0.5 cm, advantageously at least 2 cm, and especially advantageously at least 5 cm from each point of the component. Preferably, the sensor unit is spaced apart by at least 1 cm, advantageously at least 3 cm, and especially advantageously at least 10 cm, from components of the handheld power tool which perform electrical driving work in at least one operating state.

In an advantageous embodiment of the invention, it is proposed that the handheld power tool device has an additional handle, in which the sensor unit is disposed. In particular, the term “additional handle” should be understood to mean a handle which is connected to the housing on one side of the housing of the handheld power tool and is oriented toward a tool insert fastener of the handheld power tool; that is, in particular it is oriented downstream of a main handle in terms of the main working direction. Preferably, the additional handle is spaced apart from a rechargeable battery of the handheld power tool and/or from a power connection of the handheld power tool by at least 5 cm and advantageously at least 10 cm. Advantageously, the additional handle can be retrofitted onto the handheld power tool. Because of the disposition of the sensor unit in the additional handle, the sensor unit can advantageously be located far away from sources of interference that influence the Earth's magnetic field, and as a result it can operate especially reliably. It is also proposed that influence on a measurement of the Earth's magnetic field be reduced by means of lubrication with suitable materials, by twisting opposite current-carrying cords, and/or by other measures that appear useful to one skilled in the art.

In a further feature, it is proposed that the safety mechanism has a transmission, which in at least one operating state transmits a sensor parameter in wireless fashion, as a result of which in a structurally simple way, an advantageous disposition of the sensor unit is possible, in particular in the additional handle and without conductive contacts being located on the outside. The phrase “transmit in wireless fashion” should be understood in particular to mean that the transmission outputs a signal containing information about the sensor parameter over an electrically nonconductive distance, in particular to a receiver of the handheld power tool. Preferably, the transmission transmits the sensor parameter by means of a radio signal. Alternatively or in addition, the transmission could transmit the sensor parameter by means of an inductive signal, an ultrasonic signal, an infrared signal, and/or some other signal appearing useful to one skilled in the art.

It is furthermore proposed that the safety mechanism has an energy receiving device, which is provided for receiving operating energy transmitted in wireless fashion. The term “energy receiving device” should be understood in particular to mean a coil and/or some other means that appears useful to one skilled in the art. The term “operating energy” should be understood in particular to mean energy for supplying the sensor unit and/or in particular the transmission. Because of the energy receiving device, it is advantageously possible to dispense with energy transmission by wire, such as telephone landlines, and in particular to dispense with external contacts on the additional handle; as a result, great safety and high reliability can be achieved.

It is also proposed that the energy receiving device, in at least one operating state, receives energy output at least by a drive motor, as a result of which a separate energy-emitting device can advantageously be dispensed with. As a result, engineering effort and expense can be avoided and fewer structural parts are needed. The phrase “energy output by a drive motor” should be understood in particular to mean some of the energy of a magnetic field that rotates a rotor of the drive motor. This technique, known to one skilled in the art as “energy harvesting” collects electromagnetic energy, which in this case originates mainly in the drive motor, and makes it available as operating energy to an energy consumer.

The invention is also based on a handheld power tool with a handheld power tool device; all handheld power tools that appear useful to one skilled in the art, such as rotary hammers, screwdrivers, milling cutters, angle sanders, multifunction tools, and/or in particular power drills, would be conceivable for operation with a handheld power tool device, and as a result an especially safely usable handheld power tool can be furnished. Moreover, the handheld power tool and the handheld power tool device can advantageously be adapted to one another.

The invention is furthermore based on a method for operating a handheld power tool device, in which at least one safety mechanism intervenes in an uncontrolled blocking situation.

It is proposed that for detecting an uncontrolled blocking situation, a sensor unit of the safety mechanism detects an orientation parameter directly, and as a result, especially great safety can be achieved, particularly even in the presence of heavy vibration and in the event of a slow rotation of the handheld power tool, which causes a slight acceleration.

The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of preferred embodiments taken in conjunction with the drawings, in which:

FIG. 1 schematically shows a handheld power tool having a handheld power tool device according to the invention;

FIG. 2 schematically shows a path of communication between a sensor unit and a computation unit of the handheld power tool device of FIG. 1 ; and

FIG. 3 schematically shows a further exemplary embodiment of the handheld power tool device of FIG. 1 .

FIG. 1 shows a handheld power tool 38 a , which has a handheld power tool device 10 a that is in accordance with the invention. The handheld power tool 38 a is embodied as a cordless impact hammer/impact drill. It has a drive motor 36 a , a tool insert fastener 40 a , a pistol-shaped housing 42 a , and a battery interface 44 a . The tool insert fastener 40 a is disposed on a front side 46 a of an upper, essentially tubular region 48 a of the housing 42 a . The drive motor 36 a is disposed in the housing 42 a on a back side 50 a of the upper region 48 a of the housing 42 a . All the electrical cords of the handheld power tool 38 a that carry operating power are embodied in twisted form.

During an operation, the drive motor 36 a drives the tool insert fastener 40 a to rotate about an axis of rotation 52 a . The handheld power tool 38 a has an additional handle fastener 54 a , which fastens an additional handle 28 a movably about the axis of rotation 52 a . The additional handle fastener 54 a is disposed on the outside of the housing 42 a , between the drive motor 36 a and the tool insert fastener 40 a . The battery interface 44 a is disposed on an end of the housing 42 a that is oriented away from the tool insert fastener 40 a.

The handheld power tool device 10 a has a safety mechanism 12 a , a sensor unit 14 a , a computation unit 22 a , and the additional handle 28 a . In an uncontrolled blocking situation, the safety mechanism 12 a intervenes and interrupts a power emission from the tool insert fastener 40 a by switching the drive motor 36 a to be currentless, or in other words shuts the drive motor off. The sensor unit 14 a is disposed in the additional handle 28 a , specifically on an end 56 a of the additional handle 28 a that in an installed state is remote from the additional handle fastener 54 a . Thus the sensor unit 14 a is spaced apart from components which influence a measurement of the Earth's magnetic field 20 a , such as the drive motor 36 a , the tool insert fastener 40 a , and a gear, not shown, of the handheld power tool 38 a . The sensor unit 14 a has two Hall sensors, not identified by reference numeral, which during an operation, to detect an uncontrolled blocking situation, directly detect two orientation parameters 16 a , 18 a , by jointly detecting a parameter of a quantity of the Earth's magnetic field 20 a perpendicular to the axis of rotation 52 a.

FIG. 2 schematically shows the communication and data processing from the sensor unit 14 a to the drive motor 36 a . The Hall sensors of the sensor unit 14 a detect two different orientation parameters 16 a , 18 a , which describe an orientation of the handheld power tool 38 a and which are embodied as two components of a vector of the Earth's magnetic field 20 a . The orientation parameters 16 a , 18 a are oriented perpendicular to the axis of rotation 52 a and perpendicular to one another. A communication means 58 a of the sensor unit 14 a digitizes the sensor parameters 32 a output by the Hall sensors and outputs them as data 60 a , coded by a transmission method that appears useful to one skilled in the art, to a transmission means 30 a of the safety mechanism 12 a.

The transmission means 30 a is embodied as an amplifier. During an operation, it transmits the data 60 a having the sensor parameters 32 a in wireless fashion, by means of a coil 62 a of the safety mechanism 12 a that is disposed in the additional handle 28 a , to a coil 64 a of the safety mechanism 12 a that is disposed in the housing 42 a . This coil 64 a is connected to a receiving means 66 a , which is embodied as an amplifier with a filter. The receiving means 66 a transmits the data 60 a to a communication means 68 a of the computation unit 22 a . Communication between the sensor unit 14 a and the computation unit 22 a takes place in a simplex mode, but alternatively or in addition it could take place in a half-duplex or full-duplex mode.

The handheld power tool 38 a has a main handle 70 a . The main handle 70 a is disposed on an end of the housing 42 a that is remote from the tool insert fastener 40 a , between the drive motor 36 a and the battery interface 44 a . The computation unit 22 a is disposed in the main handle 70 a of the handheld power tool 38 a . The computation unit 22 a has a processor, a memory with operating and calculation routines, and the communication means 68 a for data input and data output. A first routine 72 a decodes the coded data 60 a and thus ascertains the sensor parameters 32 a . From the sensor parameters 32 a , a second routine 74 a calculates an orientation of the handheld power tool 38 a relative to the Earth's magnetic field 20 a about the axis of rotation 52 a . A third routine 76 a of the computation unit 22 a compares a calculated orientation with an earlier orientation, stored in memory, which was measured at the beginning of the work session, and thus compares it with an orientation parameter 16 a , 18 a measured at staggered times. To that end, the routine 76 a uses a formula which appears useful to one skilled in the art and which, from orientation parameters 16 a , 18 a of two different vectors, determines an angle located between the vectors. A fourth routine 78 a compares a resultant change in orientation 24 a with a shutoff threshold value 26 a and outputs a shutoff parameter 80 a . A fifth routine 82 a , which controls the drive motor 36 a on the basis of a user input, evaluates the shutoff threshold value 80 a and, in an uncontrolled blocking situation, switches off an energy supply to the drive motor 36 a . Alternatively or in addition, the fifth routine 82 a could open a coupling between the drive motor 36 a and the tool insert fastener 40 a and/or could mechanically block a drive train of the handheld power tool 38 a , or in other words in particular the tool insert fastener 40 a.

The safety mechanism 12 a has an energy receiving means 34 a , which is embodied in one piece with the coil 62 a disposed in the additional handle 28 a . The energy receiving means 34 a is disposed on a side of the additional handle 28 a that is connected to the housing 42 a of the handheld power tool 38 a . The energy receiving means 34 a receives operating energy, transmitted in wireless fashion, which supplies the sensor unit 14 a and the transmission means 30 a . Alternatively or in addition, an energy storing means, not shown in detail, could supply the sensor unit 14 a and the transmission means 30 a . The operating energy is sent from the coil 64 a disposed in the housing 42 a . This coil 64 a is supported with the additional handle fastener 54 a rotatably, essentially about the axis of rotation 52 a.

The safety mechanism 12 a has a user output, not shown in detail, which informs a user of readiness for use of the safety mechanism 12 a before a work procedure. If the safety mechanism 12 a is not ready for use, for instance if a quantity of the orientation parameter 16 a , 18 a is too low because the vector of the Earth's magnetic field 20 a oriented parallel to the axis of rotation 52 a , or if the computation unit finds that the additional handle 28 a is not connected to the housing 42 a of the handheld power tool 38 a , then the fifth routine 82 a reduces a maximum torque of the drive motor 36 a.

In FIG. 3 , a further exemplary embodiment of the invention is shown. To distinguish between the exemplary embodiments, the letter a in the reference numerals for the exemplary embodiment of FIGS. 1 and 2 is replaced by the letter b in the reference numerals of the exemplary embodiment in FIG. 3 . The ensuing descriptions are limited essentially to the differences between the exemplary embodiments; with regard to components, characteristics and functions that remain the same, reference can be made to the description of the other exemplary embodiments, especially in FIGS. 1 and 2 .

FIG. 3 shows a handheld power tool 38 b , with a handheld power tool device 10 b that has a safety mechanism 12 b and a sensor unit 14 b . The safety mechanism 12 b intervenes in an uncontrolled blocking situation. The sensor 14 b , during an operation, detects two orientation parameters 16 b , 18 b directly ( FIG. 2 ). The safety mechanism 12 b has an energy receiving means 34 b , which during an operation receives energy output in wireless fashion by a drive motor 36 b of the handheld power tool 38 b . An additional handle 28 b is connected by means of a clamping ring 84 b to a tubular region of the handheld power tool 38 b . The handheld power tool device 10 b has a transmission means 30 b , which transmits coded data 60 b by radio waves.

The sensor unit 14 b has three Hall sensors, not identified by reference numeral. As a result, the sensor unit 14 b can entirely determine a vector of the Earth's magnetic field 20 b , and thus especially great safety can be attained, especially if a direction of the vector of the Earth's magnetic field 20 b deviates only slightly from a direction of an axis of rotation 52 b of a tool insert fastener 40 b.

The foregoing relates to preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.