Patent Document

[0001]    This application claims priority under 35 U.S.C. §119 to patent application no. DE 10 2013 202 964.0, filed on Feb. 22, 2013 in Germany, the disclosure of which is incorporated herein by reference in its entirety. 
       BACKGROUND  
       [0002]    Handheld power tools, such as angle grinders, are known in the prior art. 
       SUMMARY  
       [0003]    The disclosure is based on a handheld power tool, in particular an angle grinder. 
         [0004]    It is proposed that the handheld power tool comprises at least one boost mode unit, which is intended for providing a boost mode. A “boost mode” should be understood in this connection as meaning in particular an operating mode of the handheld power tool in which a power output of the drive unit in particular of at least 130%, preferably of at least 140%, with preference of at least 150% and with particular preference of at least 160% of a nominal power output of the drive unit is made available, at least for a time. In a particularly preferred exemplary embodiment, in the boost mode a power output of the drive unit that is at least 180% of the nominal power output of the drive unit can be made available for a short time. “For a short time” should be understood in this connection as meaning in particular less than 60 s, preferably less than 45 s, with preference less than 30 s and with particular preference less than 15 s. “Intended” should be understood as meaning in particular specially programmed, designed, configured and/or equipped. 
         [0005]    The configuration according to the disclosure allows an advantageously powerful, operator-friendly and versatile handheld power tool to be achieved. 
         [0006]    It is also proposed that the handheld power tool has a switching-over unit, which is intended for switching over at least between a conventional mode and the boost mode. A “conventional mode” should be understood in this connection as meaning in particular an operating state which corresponds at least partially, preferably at least for the most part and with particular preference at least almost completely to an operating and/or working mode of an already known handheld power tool and which is intended for making continuous operation of the handheld power tool possible. Preferably, in the conventional operating mode a maximum power output of the drive unit which corresponds in particular by at least 80%, preferably at least 90%, with preference at least 100% and with particular preference at least 110% to a nominal power output of the drive unit is made available. In the conventional operating mode, the maximum power output of the drive unit is in particular at most 120% of the nominal power output of the drive unit. In the conventional operating mode, the handheld power tool preferably has in an operating and/or working state a maximum retrievable energy consumption which is in particular less than 95%, preferably less than 90%, with preference less than 85% and with particular preference less than 80% of a maximum retrievable energy consumption of the handheld power tool in an operating and/or working state in a boost mode, while the type of operation is identical and/or at least comparable. In the conventional mode, the handheld power tool may make a lower power output available in an operating and/or working state than in a boost mode. As a result, a handheld power tool which with preference can be used flexibly and is adapted to a respective application can be achieved. 
         [0007]    What is more, it is proposed that the handheld power tool has a sensor unit, which is intended for sensing at least one operating parameter at least in the boost mode. The operating parameter may be formed in particular by a temperature, a rotational speed, a power take-up, a time period, and/or some other characteristic variable of the handheld power tool that appears to be appropriate to a person skilled in the art, in particular in an operating state. As a result, operation of the handheld power tool which is with preference inexpensive, powerful and consequently operator-friendly can be achieved in an advantageously easy way. 
         [0008]    Moreover, it is proposed that the sensor unit is at least partially coupled to the boost mode unit. “Coupled” should be understood in this connection as meaning in particular that two components are formed at least partially as connected to one another, in particular for a transmission of information. The boost mode unit is preferably coupled to the sensor unit electronically. As a result, a preferred high level of operator convenience can be achieved. 
         [0009]    Furthermore, it is proposed that the boost mode unit comprises at least one open-loop and/or closed-loop control unit, which is intended for open-loop and/or closed-loop control of at least one drive unit. “Open-loop and/or closed-loop control” should be understood in this connection as meaning in particular a process that is at least partially independent of an operating state of the drive unit and/or of an electronics unit and is at least partially intended for at least partially actively influencing operation at least of the drive unit and/or at least partially adapting and/or approximating the operation of the drive unit to a prescribed sequence and/or in particular changing, in particular actively changing, dynamically variable operating parameters of the drive unit, preferably in a way corresponding to an algorithm. The open-loop and/or closed-loop control unit may in particular be at least partially mechanically formed, with particular preference at least partially electronically formed. Preferably, the open-loop and/or closed-loop control unit additionally has a computing unit and in particular, in addition to the computing unit, a memory unit with an open-loop and/or closed-loop control program stored therein, which is intended for being performed by the computing unit. In a particularly preferred exemplary embodiment, an open-loop and/or closed-loop control unit is at least partially formed in one piece with the electronics unit, with software and/or firmware of the electronics unit at least partially being intended for open-loop and/or closed-loop control and/or for switching over between the operating modes. 
         [0010]    A “drive unit” should be understood in this connection as meaning in particular a unit which is intended for driving an insert tool coupled to the handheld power tool in an operating state. The drive unit preferably comprises at least one electric motor. However, it is also conceivable that the drive unit is at least partially formed such that it can be driven pneumatically and/or can be driven in some other way that appears appropriate to a person skilled in the art. An “electronics unit” should be understood in this connection as meaning in particular a unit which is intended at least partially for open-loop and/or closed-loop control, in particular of the drive unit of the handheld power tool, at least in an operating state of the handheld power tool. Preferably, the electronics unit comprises at least one motor controller of the drive unit. The electronics unit preferably has electronic components, such as in particular at least one transistor, at least one capacitor, at least one processor, with particular preference at least one field-effect transistor (MOSFET) and/or at least one bipolar transistor, in particular with an insulated gate electrode (IGBT). As a result, an advantageously powerful, operator-friendly and versatile handheld power tool can be achieved. 
         [0011]    Moreover, it is proposed that the open-loop and/or closed-loop control unit is intended for controlling the boost mode unit in an open-loop or closed-loop manner at least in dependence on the operating parameter. As a result, a handheld power tool which is advantageously powerful and is adapted to a respective application can be achieved in an advantageously easy way. 
         [0012]    What is more, it is proposed that the drive unit comprises at least one EC motor. An “EC motor” should be understood in this connection as meaning in particular a brushless, electrically commutated motor. As a result, a configuration of the drive unit of the handheld power tool that is with preference powerful, advantageously compact and inexpensive can be achieved. 
         [0013]    Furthermore, a boost mode unit of a handheld power tool according to the disclosure is proposed. 
         [0014]    Moreover, a method for operating a handheld power tool according to the disclosure in a boost mode of a boost mode unit is proposed. 
         [0015]    The handheld power tool according to the disclosure should not be restricted here to the application and embodiment described above. In particular, the handheld power tool according to the disclosure may have a different number of individual elements, components and units than the number mentioned here to perform a functioning mode that is described here. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    Further advantages emerge from the following description of a drawing. In the drawing, three exemplary embodiments of the disclosure are represented. The drawing, the description and the claims contain numerous features in combination. A person skilled in the art will expediently also consider the features individually and put them together to form meaningful further combinations. 
           [0017]    In the drawings: 
           [0018]      FIG. 1  shows a handheld power tool according to the disclosure in a schematic, perspective view, 
           [0019]      FIG. 2  shows the handheld power tool according to the disclosure in a schematic representation in a sectional view and 
           [0020]      FIG. 3  shows a diagram for the schematic representation of a power characteristic of the handheld power tool according to the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    In  FIG. 1 , a handheld power tool is represented. The handheld power tool is formed by an angle grinder. However, other configurations of the handheld power tool that appear appropriate to a person skilled in the are also conceivable, such as for example as a power drill, hammer drill, oscillating handheld power tool or orbital sander. The handheld power tool comprises a housing  20 . The housing  20  is formed from a plastic. The housing  20  forms a main handle  22 , which is intended for being grasped by a hand of an operator. When viewed in the main direction of extent  24  of the handheld power tool, a power cable  26  is arranged at one end of the housing  20 . The power cable  26  is intended for supplying electrical power to a drive unit  18  of the handheld power tool. The power cable  26  is intended for being connected to an electrical power supply system. For this purpose, the power cable  26  has a plug element (not represented). However, it is also conceivable that the handheld power tool is formed by a battery-operated handheld power tool. The handheld power tool also has a switching element  28 , which is formed such that it can be actuated by an operator. The switching element  28  is intended for activation of the drive unit  18 . The switching element  28  is formed by a pawl. 
         [0022]    The handheld power tool also has a transmission housing  30 . The transmission housing  30  is connected to the housing  20  at an end of the housing  20  that is opposite from the power cable  26 . The transmission housing  30  is formed from a metal. The transmission housing  30  is formed from aluminum. The handheld power tool comprises a tool holder  32  (not represented any more specifically), which is intended for receiving an insert tool  34  and captively holding it. The insert tool  34  is formed by a grinding disk. The insert tool  34  is detachably connected to the tool holder  32 . When viewed perpendicularly to the main direction of extent  24  of the handheld power tool, the tool holder  32  is arranged at an open end of the transmission housing  30 . The tool holder  32  protrudes out of the transmission housing  30 . Moreover, a protective shroud  36  is coupled to the tool holder  32 . The protective shroud  36  is detachably connected to the handheld power tool. 
         [0023]    The handheld power tool also has an additional handle  38 . The additional handle  38  is intended for being grasped by a further hand of the operator. The additional handle  38  is detachably coupled to the handheld power tool. In a state in which the additional handle  38  is mounted on the handheld power tool, a main direction of extent  40  of the additional handle  38  runs perpendicularly to the main direction of extent  24  of the handheld power tool and parallel to a main plane of extent of the insert tool  34 . 
         [0024]    The handheld power tool has the drive unit  18  and an electronics unit  42  ( FIG. 2 ). The housing  20  of the handheld power tool encloses the drive unit  18  and the electronics unit  42 . The drive unit  18  comprises an electric motor. The drive unit  18  comprises an EC motor. The drive unit  18  has a driven shaft  44 , which is connected by way of a transmission unit  46  to a drive shaft  48 . The transmission unit  46  has an angle-gear transmission (not represented). The drive shaft  48  is intended for driving an insert tool  34  (not represented here), which is coupled to the tool holder  32 . The drive shaft  48  is connected to the tool holder  32 . The drive shaft  48  is coupled to the tool holder  32  with positive and/or non-positive engagement. The drive shaft  48  extends perpendicularly to the driven shaft  44 . The drive shaft  48  runs perpendicularly to the main direction of extent  24  of the handheld power tool. 
         [0025]    The drive unit  18  is operatively connected to the electronics unit  46 . The drive unit  18  is connected to the electronics unit  42  electronically. The electronics unit  42  is intended for open-loop or closed-loop control of the drive unit  18 . The electronics unit  42  may alternatively or additionally also be intended for open-loop or closed-open loop control of a further functional unit that appears appropriate to a person skilled in the art. The electronics unit  42  comprises field-effect transistors. The electronics unit  42  comprises metal-oxide semiconductor field-effect transistors (MOSFETs). Alternatively or additionally, the electronics unit  42  may also comprise other electronic components that appear appropriate to a person skilled in the art, such as for example a bipolar transistor with an insulated gate electrode (IGBT). 
         [0026]    The handheld power tool comprises a boost mode unit  10 , which is intended for providing a boost mode. The boost mode unit  10  is formed in one piece with the electronics unit  42 . The electronics unit  42  is intended also for making a conventional mode available. The handheld power tool has a switching-over unit  12 , which is intended for switching over between the conventional mode and the boost mode. The switching-over unit  12  comprises a switching-over element  50  that can be actuated by an operator. The switching-over element  50  is formed by a pawl. The switching-over element  50  is formed in one piece with the switching element  28 . However, it is also conceivable that the switching-over unit  12  is intended for an autonomous switching over between the conventional mode and the boost mode that is independent of an operator. 
         [0027]    The handheld power tool has a sensor unit  14 , which is intended for sensing an operating parameter in the boost mode. The sensor unit  14  is intended for sensing a number of operating parameters in the boost mode. The sensor unit  14  is coupled to the boost mode unit  10 . The sensor unit  14  is coupled to the boost mode unit  10  electronically. The sensor unit  14  is intended for directly sensing the operating parameters to be sensed. However, it is also conceivable that the sensor unit  14  is intended for indirectly determining the operating parameters to be sensed, such as for example by an evaluation, conversion and/or extrapolation of values of adjacent components and/or indirect measurements. 
         [0028]    The sensor unit  14  comprises one or more sensor elements. A first sensor element  52  is intended for sensing a temperature of the drive unit  18 . Alternatively or additionally, it is also conceivable that the sensor unit  14  is intended for sensing a temperature of the electronics unit  42  and/or some other functional unit of the handheld power tool that appears appropriate to a person skilled in the art, such as for example output stages, transistors or a motor winding. The first sensor element  52  is formed as a temperature sensor. The sensor unit  14  comprises a further sensor element  54 , which is intended for sensing a time parameter. The further sensor element  54  comprises a time sensing element  56 . The time sensing element  56  is intended for sensing a period in which the handheld power tool is operated in a boost mode. Furthermore, the time sensing element  56  is intended for sensing a period since the handheld power tool was operated in a boost mode. However, it is also conceivable that the sensor unit  14  is intended for sensing a rotational speed and/or a power take-up of the drive unit  18  and/or some other operating parameter of the handheld power tool that appears appropriate to a person skilled in the art. 
         [0029]    The boost mode unit  10  comprises an open-loop and/or closed-loop control unit  16 , which is intended for open-loop and/or closed-loop control of the drive unit  18 . The open-loop and/or closed-loop control unit  16  is formed as an open-loop control unit  58 , which is intended for open-loop control of the drive unit  18 . Alternatively or additionally, it is also conceivable that the open-loop and/or closed-loop control unit  16  is formed as a closed-loop control unit, which is intended for closed-loop control of the drive unit  18 . The open-loop control unit  58  is intended for controlling the boost mode unit  10  in an open-loop manner in dependence on the operating parameter formed by the temperature of the drive unit  18 . The open-loop control unit  58  is also intended for controlling the boost mode unit  10  in an open-loop manner in dependence on the further operating parameter sensed by the time sensing element  56 . 
         [0030]    The handheld power tool also comprises the switching-over unit  12 , which is intended for switching over between a conventional mode and a boost mode in an operating state of the handheld power tool. The switching-over unit  12  comprises a switching-over element  50 , which is intended for switching over between a conventional mode and a boost mode in an operating state of the handheld power tool. The switching-over element  50  is formed in one piece with the switching element  28 . However, it is also conceivable that the switching-over element  50  is formed separately from the switching element  28  and/or is formed as a switching slide or in some other way that appears appropriate to a person skilled in the art. The switching element  28  has a first switching position, which is reached by an operator pressing the switching element  28  formed by the pawl toward the housing  20  of the handheld power tool. The switching-over element  50  and the switching element  28  are coupled to the electronics unit  42 . When the switching element  28  is actuated by an operator, the drive unit  18  is activated by way of the electronics unit  42  and the handheld power tool is put into an operating state. 
         [0031]    In this first switching position of the switching element  28 , the handheld power tool works in a conventional operating mode. The electronics unit  42  thereby activates the drive unit  18  in such a way that a motor power output P conv  of the drive unit  18  in the operating state is in the range of a nominal power output P nom  ( FIG. 3 ). By the operator pressing the switching element  28  with increased expenditure of force, the switching element  28  can be brought into a further switching position. In this further switching position of the switching element  28 , the handheld power tool works in a boost mode. The electronics unit  42  thereby activates the drive unit  18  in such a way that a motor power output P boost  of the drive unit  18  in the boost mode is higher than the motor power output P conv  in a conventional operating mode. The motor power output P boost  of the drive unit  18  in the boost mode significantly exceeds the nominal power output P nom . The motor power output P boost  of the drive unit  18  in the boost mode is about 150% of the nominal power output P nom . Alternatively or additionally, it is also conceivable that the motor power output P boost  of the drive unit  18  in the boost mode is for a short time about 180% of the nominal power output P nom . 
         [0032]    An operating period of the handheld power tool in boost mode is limited, so that premature wearing of the handheld power tool can be limited or prevented. For this, in the boost mode the first sensor element  52  of the sensor unit  14  senses the temperature of the drive unit  18 . The sensed values of the first sensor element  52  of the sensor unit  14  are passed on to the open-loop control unit  58  of the boost mode unit  10 . Here, the sensed values are compared with prescribed limit values. If the sensed values, and consequently the temperature of the drive unit  18 , exceed the limit values, the boost mode is ended, in order to prevent the drive unit  18  from being damaged by overheating. Moreover, the further sensor element  54  of the sensor unit  14  senses a period in which the handheld power tool is operated in the boost mode. If a prescribed maximum period t max , which is stored in the open-loop control unit  58 , is exceeded without the boost mode having been ended on account of the temperature exceeding the limit, the boost mode is automatically ended. As a result, damage to the drive unit  18  can be dependably prevented. 
         [0033]    The further sensor element  54  of the sensor unit  14  is also intended for sensing a period that has elapsed since the ending of the boost mode. This value is passed on to the open-loop control unit  58  and compared with a prescribed value stored in the open-loop control unit  58 . If the sensed value goes below the prescribed value, renewed activation of the boost mode is blocked by the open-loop control unit  58  and is consequently not possible. Only after the elapse of a minimum period that must have elapsed after operating the handheld power tool in the boost mode can the boost mode be activated once again by the operator. 
         [0034]    Once the boost mode has been automatically ended by the open-loop control unit  58  on account of the maximum temperature of the drive unit  18  being exceeded or on account of the prescribed maximum period of time t max  being exceeded, the handheld power tool continues to run in the conventional operating mode even in the further switching position of the switching element  28 . The operator can of its own accord change from the boost mode into the conventional operating mode, in that the operator brings the switching element  28  from the further switching position into the first switching position by reducing the force expended. 
         [0035]    However, it is also conceivable that the power characteristic of the drive unit  18  in the boost mode can be dynamically adapted in dependence on the temperature of the drive unit  18  sensed by the first sensor element  52 . For example, the motor power output P boost  in the boost mode may be thereby reduced as the temperature of the drive unit  18  increases. Furthermore, it is also conceivable to increase a cooling power output of a cooling unit (not represented) of the handheld power tool during operation of the handheld power tool in a boost mode, in order to slow down or counteract a rise in temperature due to the increased power take-up of the drive unit  18 . 
         [0036]    The handheld power tool also has an information unit  60 , which is intended for informing an operator of the handheld power tool about an operating mode of the handheld power tool in an operating state. The information unit  60  is coupled to the electronics unit  42 . The information unit  60  is coupled to the electronics unit  42  electronically. The information unit  60  is incorporated in the housing  20 . The information unit  60  is intended for emitting an optical signal that can be perceived by an operator. However, it is also conceivable that the information unit  60  is intended for emitting an acoustic and/or haptic signal that can be perceived by an operator. The information unit  60  is formed by a display. However, it is also conceivable that the information unit  60  is formed as an LED, loudspeaker and/or in some other way that appears appropriate to a person skilled in the art. The information unit  60  is intended for informing an operator about a remaining maximum period of time that is left to use the boost mode or about a period of time that is left until the next-possible time at which the boost mode can be activated once again.

Technology Category: 7