Patent Publication Number: US-2019184528-A1

Title: Attachment device

Description:
FIELD OF THE INVENTION 
     The present invention relates to an attachment device for mounting to a handheld power tool and a related handheld power tool system. 
     BACKGROUND INFORMATION 
     Patent document DE 10 2005 048 345 A1 discusses an attachment device for mounting to a handheld power tool, including a tool fixture for receiving an insertable tool, and including at least one rotary impact mechanism, which, in at least one operating state, is configured to generate a rotary impact pulse for an impact drive of the tool fixture. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an attachment device for mounting to a handheld power tool, including a tool fixture for receiving an insertable tool, and including at least one rotary impact mechanism, which, in at least one operating state, is configured to generate a rotary impact pulse for an impact drive of the tool fixture. 
     It is provided that the rotary impact mechanism include at least one planetary gear set, which is configured to convert a rotational speed and/or a torque of an output shaft of the handheld power tool to a rotational speed and/or a torque of the tool fixture. 
     In this connection, an “attachment device” should be understood as, in particular, a device, which is configured for operation by a base device, which includes a drive unit for a rotary drive. The attachment device may be provided for a specific intended use. The attachment device may be intended exclusively for operation by a base device, in particular, by a handheld power tool. The attachment device may be replaceable with other attachment devices having the same intended use or having a different intended use. It particularly may be provided for the base device to be operable independently of the attachment device. A “handheld power tool” should be understood as, in particular, a machine tool, which may be held in the hand for use by an operator, but is advantageously a cordless screwdriver, a drill, a hammer drill and/or percussion hammer, a milling tool, a grinder, and/or a multifunctional tool. The handheld power tool may include a drive unit for a rotary drive, which may be, an electric drive unit, for example, an electric motor. The handheld power tool may be operable independently of an electrical network. The handheld power tool may be connectible to an energy storage device, for example, a battery pack. A “tool fixture” should be understood as, in particular, a component part, which is configured to hold a machining tool in a mounting region and to enter into a form-locked and/or force-locked connection with the machining tool in the circumferential direction. 
     In this connection, a “rotary impact mechanism” is to be understood as, in particular, a striking mechanism, which is configured to convert an at least substantially continuous power output of a drive unit to a rotational pulse in the form of a stroke. The rotary impact mechanism may take the form of, in particular, a cam-type rotary impact mechanism or a V-groove rotary impact mechanism. In this connection, a “rotational impact pulse” is to be understood as, in particular, a periodically repeatable striking pulse. The striking pulse may take the form of a radial pulse and includes a radially directed component, whose magnitude is at least 80 percent, which may be 90 percent, and particularly may be 95 percent of a total magnitude of the striking pulse. In this connection, directional information, such as “axial,” “radial,” and “in the circumferential direction,” should be understood to be, in particular, in relation to an axis of rotation. In this context, “provided” is to be understood as, in particular, specially configured and/or equipped. That an object is provided for a particular function, is to be understood to mean that, in particular, the object fulfills and/or executes this particular function in at least one application state and/or operating state. A “planetary gear set” is to be understood as, in particular, a gear unit, which includes at least one planet, which is connected to a planet carrier and is coupled to a ring gear in an outward radial direction and/or coupled to a sun gear in an inward radial direction. The sun gear, the planet and/or the ring gear may be made up of, in particular, circular gear wheels or of non-circular gear wheels matched to each other. A plurality of planetary gear sets may be connected in series, and/or a plurality of stages may be interposed between the planet gear and ring gear. A “ring gear” should be understood as, in particular, a gear wheel, which has a rim that is formed in the shape of a cylinder sleeve or in the shape of a discontinuous cylinder sleeve. As an alternative to the use of a planetary gear set, it is also conceivable to use a different type of gear construction appearing suitable to one skilled in the art, for example, a spur gear unit, and/or to use a combination of different types of gear construction. 
     Using such a refinement, an attachment device of the species may be provided, which has advantageous configuration features. In particular, by using a planetary gear set, an advantageously compact, inexpensive, efficient and/or robust supplementary device may be provided for implementing a rotary impact drive on a handheld power tool. In this manner, a range of application of a handheld power tool may be expanded in an advantageous manner. An attachment device may be provided, which is usable with different base devices, in particular, different handheld power tools. An attachment device for a large number of different insertable tools may be provided. 
     The rotary impact mechanism advantageously includes at least one drive element, which has an interconnection region that is connectible to an insertable tool fixture of the handheld power tool so as to be able to transmit power. An “insertable tool fixture” is to be understood as a fixture for at least an insertable tool, for example, for an insertable bit. The insertable tool fixture is advantageously formed as part of a machine interface, which is configured to couple the attachment devices simultaneously to a housing unit and to an output shaft. In this connection, a “drive element” should be understood as, in particular, an element, which is configured to transmit and/or relay a driving motion, which may be, an angular motion and/or rotational pulse. The drive element may be configured to transmit an angular motion in an axial direction and takes the form of, for example, a shaft. The drive element may be capable of being attached onto the insertable tool fixture. In this manner, an angular motion may be transmitted advantageously from the handheld power tool to the attachment device. 
     In addition, it is provided that at least part of the drive element be formed in one piece with a planet carrier of the planetary gear set. In particular, at least part of the drive element is formed as a spindle, which is connectible to an insertable tool fixture of the handheld power tool in an axially movable and rotatably fixed manner. “Formed in one piece” is to be understood as, in particular, at least integrally joined, for example, by a welding method, an adhesive bonding method, an injection molding method, and/or another method appearing to be suitable to one skilled in the art; and/or understood as formed advantageously in one piece, such as by production from casting and/or by production in a single-component or multicomponent injection molding method, and advantageously from a single blank. In a coupled state, the drive element advantageously mates with an opening of the insertable tool fixture. It is also conceivable for the drive element to have a holding fixture, with which, in a coupled state, an element of the insertable tool fixture engages. In this manner, the rotary impact mechanism may be joined to the handheld power tool particularly simply, rapidly and reliably, so as to be able to transmit power. A rotary impact mechanism constructed particularly simply may be provided. A particularly compact, rotary impact mechanism may be provided. 
     In addition, it is provided that the planetary gear set include at least two switchable gear speeds. The planetary gear set may have a gear ratio less than 1. In particular, the planetary gear set has a gear ratio between 0.1 and 0.8. Due to this, a rotational speed of the attachment device may be adapted advantageously to a rotary impact drive. A particularly efficient attachment device may be provided. 
     In addition, it is provided that the rotary impact mechanism have a switch element for switching off striking action and/or switching on striking action. The switch element may be configured for manipulation by the operator. In particular, the switch element includes an actuating element, which is situated between the drill chuck and the coupling unit in the axial direction. “Switching off striking action” should be understood as a unit, which is provided for switching off, interrupting and/or decoupling an impact drive. The attachment device may include a rotary drive, which is usable independently of the switching-off of striking action. Alternatively, it is conceivable for the rotary impact mechanism to have no device for switching off striking action. In such a variant, the attachment device is configured for constant rotary impact operation. The switch element may be configured to bring snap-in locking elements and/or detent regions of the rotary impact mechanism out of engagement and/or to fix them in an alternately disengaged position. In this manner, an attachment device usable in a particularly flexible manner may be provided. 
     In addition, it is provided that the attachment device have a coupling unit, which is provided for coupling to a housing of the handheld power tool in a detachable, rotatably fixed manner. This may allow an advantageously reliable connection between the attachment device and a handheld power tool to be achieved. 
     In addition, the attachment device may include a positioning unit, which is provided for fixing a handle in position. The positioning unit may be compatible with a handle positioning unit of a handheld power tool, which means that a handle belonging to a handheld power tool may be used advantageously. This may allow a handle to be mounted to the attachment device in an advantageously simple manner. 
     Furthermore, a handheld power tool system is provided, including an attachment device of the present invention, and including at least one handheld power tool for driving the attachment device. The handheld power tool may take the form of a battery-operated, handheld power tool. This allows a handheld power tool system to be provided for a large range of application. A large number of operating cases and/or applications may be achieved. A particularly cost-effective, handheld power tool system for rotary impact operation may be provided. This may eliminate the need to use a specially configured impact screwdriver. A particularly lightweight and/or particularly compact, handheld power tool, in particular, a cordless screwdriver, may be provided for coupling to the attachment device. A particularly efficient, handheld power tool system may be provided. 
     Further advantages are derived from the description of the figures that follows. Two exemplary embodiments of the present invention are shown in the figures. The drawing, the description, and the claims include numerous features in combination. One skilled in the art will necessarily consider the features individually, as well, and unite them to form useful, further combinations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a side view of a system including an attachment device of the present invention, and including a handheld power tool. 
         FIG. 2  shows a perspective view of a drive and operating region of the handheld power tool. 
         FIG. 3  shows a perspective view of a detail of a machine interface of the handheld machine tool. 
         FIG. 4  shows a sectional view of the attachment device along a drive and operating axis. 
         FIG. 5  shows a schematic representation of a further exemplary embodiment, including a gear unit. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a handheld power tool system  34   a  including a handheld power tool  12   a  and including an attachment device  10   a , which has a rotary impact mechanism  20   a . Attachment device  10   a  is configured for mounting to handheld power tool  12   a  and includes a coupling unit  14   a , which is provided for coupling attachment device  10   a  to handheld power tool  12   a . Coupling unit  14   a  is configured for coupling to an insertable tool fixture  16   a  of handheld power tool  12   a . Coupling unit  14   a  is provided for coupling to a tool housing unit  58   a  of handheld power tool  12   a  in a detachable, rotatably fixed manner. Attachment device  10   a  includes a tool fixture  18   a  for holding an insertable tool. It is conceivable for handheld power tool system  34   a  to include further attachment devices, which are configured for coupling to handheld power tool  12   a . Attachment device  10   a  includes a positioning unit  100   a , which is provided for fixing a handle  102   a  in position. In at least one operating state, rotary impact mechanism  20   a  is configured to generate a rotary impact pulse for an impact drive of tool fixture  18   a . Attachment device  10   a  includes a housing unit  36   a , in which rotary impact mechanism  20   a  is situated. Rotary impact mechanism  20   a  includes a switch element  28   a  for switching off striking action and/or switching on striking action. 
     In the present exemplary embodiment, handheld power tool  12   a  takes the form of a cordless screwdriver. Handheld power tool  12   a  includes an electric drive unit  38   a , which has an electric motor. Handheld power tool  12   a  includes an output shaft  32   a , which is configured to transmit a torque and/or an angular motion generated by drive unit  38   a  (cf.  FIG. 2 ). In the present exemplary embodiment, handheld power tool  12   a  is formed in the shape of a pistol. Handheld power tool  12   a  has a driving and operating region  40   a  and a handle region  42   a . Handheld power tool  12   a  has a driving and operating axis  44   a  and a handle axis  46   a . Driving and operating axis  44   a  and handle axis  46   a  form an angle of approximately 80 degrees with each other. It is conceivable for driving and operating axis  44   a  and handle axis  46   a  to form an angle, which has a value in a range of values between 60 degrees and 90 degrees, or another value appearing suitable to one skilled in the art. It is also conceivable for driving and operating axis  44   a  and handle axis  46   a  to be positioned in alignment with each other. 
     Handheld power tool  12   a  includes a switch element, which is configured to switch on and/or switch off drive unit  38   a  and/or to set a rotational speed of handheld power tool  12   a  and/or a torque of handheld power tool  12   a . The switch element includes an actuating element  48   a , which is configured to be manipulated by a user. Actuating element  48   a  takes the form of a pressure-operated switch. Handheld power tool  12   a  includes a torque limiter, which is configured to set a maximum torque transmitted by drive unit  38   a  to output shaft  32   a . The torque limiter includes an adjusting collar  50   a , which is configured for manipulation by the user. Handheld power tool  12   a  includes a gear unit  52   a . Gear unit  52   a  is configured to convert a rotational speed and/or a torque of drive unit  38   a  to a rotational speed and/or a rotational speed of tool fixture  18   a . Gear unit  52   a  has a plurality of gear speeds, which have a different gear ratio. Handheld power tool  12   a  includes a gear changer, which is configured to set a gear speed. The gear changer includes an actuating element  54   a , which is configured to be actuated by the user. In the present exemplary embodiment, actuating element  54   a  takes the form of a sliding element. Handheld power tool  12   a  includes a rotational direction switch, which is provided for setting a direction of rotation of output shaft  32   a . The rotational direction switch includes an actuating element  56   a , which is configured for manipulation by the user. In the present exemplary embodiment, actuating element  56   a  takes the form of a sliding element. 
     Handheld power tool  12   a  includes a tool housing unit  58   a , which encloses and supports drive unit  38   a  and gear unit  52   a . Tool housing unit  58   a  extends over driving and operating region  40   a  and handle region  42   a . Handheld power tool  12   a  is configured to be supplied power by a battery device  60   a . Handheld power tool  12   a  includes a battery interface unit for battery device  60   a . The battery interface unit for battery device  60   a  is situated at an end of the handle region  42   a  facing away from driving and operating region  40   a . The battery interface unit is configured to connect a housing unit  62   a  of battery device  60   a  to tool housing unit  58   a  of handheld power tool  12   a  without a tool, in a detachably secure manner. 
     Handheld power tool  12   a  includes a machine interface  64   a , which is configured for mounting attachment device  10   a  in what may be a rotation-locked manner (cf.  FIG. 3 ). Machine interface  64   a  has a fastening element  66   a  situated at an end face of tool housing unit  58   a . At least sections of fastening element  66   a  are sleeve-shaped and/or annular. At an outer circumference, fastening element  66   a  includes at least one blocking element  68   a  and at least two retaining elements  70   a ,  72   a . Blocking element  68   a  may include at least one set of blocking gear teeth, and in the present exemplary embodiment, the at least two retaining elements  70   a ,  72   a  take the form of a type of bayonet to produce a bayonet joint. Machine interface  64   a  is provided for connecting the attachment device  10   a  mechanically. Coupling unit  14   a  of attachment device  10   a  is configured for detachable mechanical coupling to machine interface  64   a.    
     Output shaft  32   a  emerges from handheld power tool  12   a  in the region of machine interface  64   a . Output shaft  32   a  has an axis of rotation, which corresponds to driving and operating axis  44   a  of handheld power tool  12   a . On a free end, output shaft  32   a  forms the insertable tool fixture  16   a  of handheld power tool  12   a . Insertable tool fixture  16   a  is configured to hold an exchangeable, insertable tool, for example, a tool bit, which may be, having a screwdriver blade, or a hex headpiece. Insertable tool fixture  16   a  takes the form of a many-sided inner holding fixture and has a polygonal cross section. Insertable tool fixture  16   a  takes the form of a hexagonal inner fixture, for example, for receiving a hex drill bit or a screw bit. 
     Coupling unit  14   a  of attachment device  10   a  is configured to interact with machine interface  64   a  of handheld power tool  12   a . Coupling unit  14   a  and machine interface  64   a  are configured to interconnect tool housing unit  58   a  of handheld power tool  12   a  and housing unit  62   a  of attachment device  10   a  in a detachable, secure manner, without a tool. Machine interface  64   a  and coupling unit  14   a  each have a form-locking region. The form-locking regions are provided for a form-locked connection with each other. Machine interface  64   a  and coupling unit  14   a  each have a force-locking region. The force-locking regions are provided for a frictional connection with each other. Coupling unit  14   a  and machine interface  64   a  are configured to lock onto each other. In the present exemplary embodiment, coupling unit  14   a  and machine interface  64   a  form a bayonet joint. Coupling unit  14   a  includes an actuating element  74   a , which is configured to release a locked connection of coupling unit  14   a  with machine interface  64   a  of handheld power tool  12   a . Tool fixture  18   a  is configured to receive an insertable tool. 
     Rotary impact mechanism  20   a  includes a drive element  22   a , which has an interconnection region  24   a ; in a state, in which the interconnection region is connected to handheld power tool  12   a  with the aid of coupling unit  14   a , the interconnection region being connectible to the insertable tool fixture  16   a  of handheld power tool  12   a  so as to be able transmit power (cf.  FIG. 4 ). Rotary impact mechanism  20   a  takes the form of a V-groove rotary impact mechanism. Rotary impact mechanism  20   a  is configured to convert a continuous power output of drive unit  38   a  of handheld power tool  12   a  to a rotational pulse in the form of a stroke. The energy release of drive unit  38   a  via a blow of a striker  104   a  of rotary impact mechanism  20   a  to a corresponding anvil  106   a  is transmitted to the insertable tool by a pulse of high power intensity. Anvil  106   a  is formed in one piece with tool fixture  18   a . Striker  104   a  is supported in such a manner, that an axial movement and radial movement are possible. The axial movement is controlled, using V-shaped grooves  108   a  and driving balls  122   a . A spring  110   a  provides for the restoring movement of striker  104   a.    
     Rotary impact mechanism  20   a  includes a planetary gear set  30   a , which is configured to convert a rotational speed and/or a torque of an output shaft  32   a  of handheld power tool  12   a  to a rotational speed and/or a torque of tool fixture  18   a . Planetary gear set  30   a  is formed to have a single stage. Planetary gear set  30   a  has a gear ratio less than 1. Planetary gear set  30   a  includes a ring gear  88   a , a planet carrier  82   a  and a sun gear  90   a . Drive element  22   a  is configured to transmit a torque and/or an angular motion of output shaft  32   a  of handheld power tool  12   a  to planetary gear set  30   a . Drive element  22   a  is formed in one piece with a planet carrier  82   a  of planetary gear set  30   a . Rotary impact mechanism  20   a  includes an intermediate shaft  112   a , which is at least substantially in alignment with output shaft  32   a  of handheld power tool  12   a . Intermediate shaft  112   a  forms the sun gear  90   a  of planetary gear set  30   a . In addition, rotary impact mechanism  20   a  includes a bearing  114   a  for supporting drive element  22   a  and a bearing  116   a  for supporting intermediate shaft  112   a . Bearings  114   a ,  116   a  take the form of rolling-contact bearings, in particular, ball bearings. 
     Interconnection region  24   a  is situated at an end of drive element  22   a  facing away from tool fixture  18   a . Interconnection region  24   a  is formed to correspond to insertable tool fixture  16   a  of handheld power tool  12   a . Interconnection region  24   a  has a cross section, which is formed to correspond to the cross section of insertable tool fixture  16   a  of handheld power tool  12   a . In the present exemplary embodiment, interconnection region  24   a  has an outer circumference in the form of a regular hexagon. In the state in which it is connected to handheld power tool  12   a , interconnection region  24   a  engages with part of insertable tool fixture  16   a . In the present exemplary embodiment, interconnection region  24   a  and insertable tool fixture  16   a  form a plug-and-socket connection. As an alternative, it is conceivable for interconnection region  24   a  to include a driving fixture, and, in a connected state, for output shaft  32   a  to engage with the driving fixture of interconnection region  24   a . Housing unit  36   a  of attachment device  10   a  includes a housing element  118   a , which is configured, in at least one operating state, to brace rotary impact mechanism  20   a  against insertable tool fixture  16   a  of handheld power tool  12   a . In the present exemplary embodiment, housing element  118   a  forms engagement devices  120   a  of coupling unit  14   a.    
     A further exemplary embodiment of the present invention is shown in  FIG. 5 . The following description and the figures are limited mainly to the differences between the exemplary embodiments; with regard to identically designated components, in particular, with regard to components having the same reference characters, reference also being able to be made, in principle, to the figures and/or the description of the other exemplary embodiments, in particular, of  FIGS. 1 through 4 . In order to distinguish between the exemplary embodiments, the letter “a” follows the reference numerals of the exemplary embodiment in  FIGS. 1 through 4 . In the exemplary embodiment of  FIG. 5 , the letter “a” is replaced by the letter “b.” 
       FIG. 5  shows a schematic representation of a further exemplary embodiment of an attachment device  10   b , which includes a rotary impact mechanism  20   b . Attachment device  10   b  is configured to be mounted on a handheld power tool  12   b  not shown in further detail and includes a coupling unit  14   b , which is provided for coupling to the handheld power tool  12   b . Coupling unit  14   b  is configured for coupling to an insertable tool fixture  16   b  of handheld power tool  12   b . Attachment device  10   b  includes a tool fixture  18   b  for holding an insertable tool. In at least one operating state, rotary impact mechanism  20   b  is configured to generate a rotary impact pulse for an impact drive of tool fixture  18   b . Attachment device  10   b  includes a housing unit  36   b , in which rotary impact mechanism  20   b  is situated. Tool fixture  18   b  is configured to receive an insertable tool. 
     Attachment device  10   b  includes a two-stage planetary gear set  30   b  having a first gear stage  76   b  and an additional gear stage  78   b . First gear stage  76   b  includes an input sun gear  80   b , a planet carrier  82   b , a plurality of planet elements  84   b ,  86   b  and a ring gear  88   b  mounted to the housing. Additional gear stage  78   b  includes a sun gear  90   b  connected to planet carrier  82   b  of first gear stage  76   b  in a rotatably fixed manner, a planet carrier  92   b , a plurality of planet elements  94   b ,  96   b  and a switch-actuating ring gear  98   b . Planetary gear set  30   b  has two switchable gear speeds. In a first of the gear speeds, switch-actuating ring gear  98   b  is mounted to the housing. In the present exemplary embodiment, switch-actuating ring gear  98   b  includes engagement devices not shown in further detail, which, in the first gear speed, are provided for a form-locked connection with housing unit  36   b  of attachment device  10   b . In another of the gear speeds, switch-actuating ring gear  98   b  is connected to planet carrier  82   b  of first gear stage  76   b  in a rotatably fixed manner. At the same time, planet elements  94   b ,  96   b  of additional gear stage  78   b  are meshed with switch-actuating ring gear  98   b . In the other gear speed, second gear stage  78   b  is short-circuited. In the other gear speed, planet carrier  92   b  of additional gear stage  78   b  has a rotational speed equal to that of sun gear  90   b.