Abstract:
A drilling apparatus has a housing, a motor in the housing, a drive spindle rotatable about an axis on the housing, a chuck body, and a plurality of jaws shiftable in the chuck body. First and second elements interconnected by a screw thread and engaged between the body and the jaws for shifting the jaws on the housing. A drive sleeve rotationally fixed to the first element is drivable by the motor.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a power drill. 
     BACKGROUND OF THE INVENTION 
     A typical power drill has a motor and a drive spindle rotatably mounted in a housing, and a drilling chuck with a chuck body in which displaceable jaws are guided by a threaded connection formed between a threaded drive member and a threaded stem element. 
     A drilling chuck of the kind described above is disclosed in DE 10 2009 026 075 (U.S. application Ser. No. 13/302,037 filed 4 Mar. 2012). It has a housing, a tubular drive spindle extending forward along an axis from the housing, a drive motor in the housing and permanently connected to the spindle for rotating the spindle about the axis, and a chuck body carried on the spindle outside the housing. An internally threaded sleeve element is provided in the spindle, and a driver, sleeve, and holder carried on the chuck body form a plurality of angularly spaced angled guides receiving respective jaws axially rearwardly braced on the driver. A stem element on the driver is threaded into the sleeve element. A rod rotationally coupled to the one of the elements extends axially through the spindle so that relative rotation of the one element and the stem shifts the jaws in the guides. A coupling rotationally fixed to the rod is axially shiftable between a tightening position engaging the housing and a drilling position engaging the chuck body. Interfitting formations on the coupling, the housing, and the chuck body rotationally lock the one element to the rod and couple the rod to the housing in the tightening position and to the chuck body in the drilling position. 
     In the drilling configuration, the coupling rod is rotationally connected to the tubular drive spindle so that, in the tightening position that serves to displace the jaws, the coupling rod is decoupled from the tubular drive spindle and is rotationally connected to the housing. In doing so, the coupling rod and the threaded stem element are fixed with respect to the rotation of the tubular drive spindle driven by the motor. The tubular drive spindle is rotationally connected to the chuck body and to the jaw holder so that the threaded drive member is screwed in and out on rotation of the chuck body, and the jaws are therefore displaced by the motor of the power drill. This is a possible way of adjusting the jaws with the help of the power drill drive. In doing so however, it is difficult for a user to fit a drilling tool in the power drill between the jaws, as the chuck body, which is on the outside of the power drill and is driven by the power drill motor, rotates during the clamping process. 
     OBJECTS OF THE INVENTION 
     It is therefore an object of the present invention to provide an improved power drill. 
     Another object is the provision of such an improved power drill that overcomes the above-given disadvantages, in particular that also provides a progressive integration of the drilling chuck with the power drill. 
     SUMMARY OF THE INVENTION 
     With a power drill of the kind described above, the object is achieved by providing a drive sleeve that is rotationally connected to the threaded stem element and that can be driven by the motor. This has the advantage that the power drill can be produced more easily, more simply and more cheaply. In addition, the compact design of the power drill guarantees that, in the drilling configuration, rotation of the threaded drive member with respect to the threaded stem element is blocked. With the power drill according to the invention, an interlock such as is shown in EP 0 017 748 [U.S. Pat. No. 4,302,021) that is intended to prevent rotation of the chuck body relative to the parts that release the jaws is therefore no longer necessary. Furthermore, a limitation of the clamping force, such as is often provided with self-tightening drill chucks, is no longer necessary. At the same time, in the drilling configuration, the torques opposing the drilling direction acting on the drilling chuck due to the drilling tool cause no relative movement of the threaded drive member relative to the threaded stem element. Incorrect clamping of the drilling tool, which would prevent the drilling chuck from being easily released, cannot occur. 
     It has been shown to be useful when a gear arrangement, preferably a planetary-gear transmission, is provided between the motor and the drive sleeve. This enables the highest possible torques to be transmitted to the drive spindle and, in the drilling configuration, also to the threaded stem element. 
     At the same time, it is particularly beneficial when the planetary-gear transmission has a sun gear that can be driven by the motor and that engages with at least one planet gear that is mounted on a planet carrier connected to the drive sleeve, and that for its part interacts with a ring gear associated with the housing. This enables the power drill drive to be applied directly to the sun gear, as a result of which the planet carrier drives the drive sleeve by the planet gear that rolls on the nonrotating ring gear. 
     It has been shown to be beneficial that the threaded stem element is formed in two parts from a threaded sleeve and an axially displaceable coupling rod that is rotationally connected thereto and is guided in the drive spindle designed as a tubular drive spindle, when the coupling rod has a coupling spur gear and the tubular drive spindle has a spindle spur gear, and when the drive sleeve and possibly the gear arrangement are axially displaceably mounted in the housing. The spindle spur gear and the coupling spur gear make it very easy to produce a torque-transmitting connection between the drive sleeve and the tubular drive spindle or coupling rod. 
     A particular embodiment is characterized in that the drive sleeve has internal gear teeth and can reversibly be brought from a tightening position, in which the coupling spur gear is engaged with the internal gear teeth, into a drilling configuration, in which the coupling spur gear and the spindle spur gear are engaged with the internal gear teeth. In the tightening position, the spindle spur gear is also engaged with the ring gear, as a result of which the tubular drive spindle is rotationally connected to the housing and to the chuck body. This ensures that the coupling rod rotates relative to the tubular drive spindle. The power drill can very easily be switched back and forth between the tightening position and the drilling configuration by the axial displacement of the drive sleeve. Here too, rotation of the threaded drive member relative to the threaded stem element is prevented by the spur gear and the spindle spur gear being driven by the drive sleeve. 
     An alternative preferred embodiment of the invention is characterized in that the drive sleeve is securely connected to the coupling spur gear and can reversibly be brought from a tightening position, in which a crown gear provided on the coupling rod is not engaged with the spindle crown gear of the tubular drive spindle, into a drilling configuration, in which the crown gear is engaged with the spindle crown gear. In this case, in the tightening position, the spindle spur gear is also engaged with the ring gear, which facilitates the rotation of the coupling rod relative to the tubular drive spindle. Axial displacement of the drive sleeve produces a rotatably fixed connection between the tubular drive spindle and the coupling rod driving the threaded sleeve, as a result of which an easy changeover is provided between the drilling configuration and the tightening position. 
     Expediently, an adjusting sleeve, which effects on axial displacement of the gear arrangement and the drive sleeve, is associated with the housing. This enables the user to switch between the tightening position and the drilling configuration manually or even electrically. For manual displacement, it can be expedient to provide a control cam in the housing. It is also conceivable to use a changeover between the two configuration positions that is realized with a solenoid, as shown in DE 10 2009 026 075. 
     At the same time, it has been shown to be particularly beneficial when the adjusting sleeve has at least one adjusting element that interacts with the ring gear, as a result of which the planetary-gear transmission can be easily displaced axially by the adjusting sleeve. 
     It has been shown to be beneficial that a cover cap that lies axially in front of the housing and is releasably connected thereto is associated with the housing, as this prevents drilling dust or other contamination getting into sensitive parts, such as into the gear arrangement of the power drill for example. 
     At the same time, it is advantageous when at least one bearing, which ensures the true running accuracy of the drilling chuck and therefore of the whole power drill, is provided between the drive spindle and the housing. 
     A further particularly preferred embodiment is characterized in that the chuck body is designed as a chuck sleeve and has at least one chuck crown gear that lies radially inward, that a spindle rod, which can be driven by the motor and that can be brought from a tightening position in which at least one spindle rod crown gear of the spindle rod is engaged with at least one planet gear and is not engaged with the chuck crown gear into a drilling configuration in which the spindle rod crown gear is engaged with the chuck crown gear, is axially displaceably guided in the chuck body, and that the drive sleeve is in the form of a ring gear that is engaged with the planet gear. Here, only one part, namely the spindle rod, is axially displaced in order to switch back and forth between the tightening position and the drilling configuration. In so doing, the spindle rod serves as a central gear that drives the planet gear, which for its part drives the drive sleeve that is in the form of a ring gear. The threaded stem element engaged with the threaded drive members provided on the jaws is driven by the drive sleeve. 
     At the same time, it has been shown to be particularly beneficial when a spring is arranged between the chuck sleeve and the spindle rod and supports these axially. This causes a resetting force of the spring to act permanently on the spindle rod, as a result of which the power drill is forced into the drilling configuration. 
     It is also advantageous when a coaxially arranged driver ring is associated with the spindle rod. This driver ring provides an additional guide for the spindle rod. In the clamping mode, the driver ring is engaged in a rotatably fixed manner with the chuck sleeve so that it is securely held and the relative rotation of the chuck sleeve relative to the spindle rod is facilitated. The driver ring can also have external gear teeth that, in the drilling mode, engage with housing gear teeth formed on the housing. 
     Furthermore, it has been shown to be beneficial when an adjusting sleeve, which effects the axial displacement of the spindle rod, is associated with the housing, where here too a mechanical, electrical or manual displacement is possible. 
     Finally, it has been shown to be preferable when the adjusting sleeve has at least one adjusting element that interacts with the driver ring, as this ensures a guided and reliable displacement of the spindle rod. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which: 
         FIG. 1  is a partly schematic axial section through a first drill according to the invention, in the clamping position; 
         FIG. 2  is a view like  FIG. 1  but in the drilling position; 
         FIG. 3  is a section taken along line of  FIG. 2 ; 
         FIGS. 4 and 5  are views like respective  FIGS. 1 and 2  of a second drill according to the invention; 
         FIG. 6  is a section taken alone line VI-VI of  FIG. 5 ; 
         FIGS. 7 and 8  are views like respective  FIGS. 1 and 2  of a third drill according to the invention; 
         FIGS. 9 and 10  are sections taken along respective line IX-IX and X-X of  FIG. 7 ; and 
         FIGS. 11 ,  12 , and  13  are sections taken along respective lines XI-XI, XII-XII, and XIII of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION 
     As seen in  FIGS. 1 to 3  a first preferred embodiment of the power drill consisting of a power drill having a motor  37  and a drive spindle  2  rotatable in a housing  1  about its axis A and fixed at its front to a chuck body  3  in which jaws  7  can be shifted axially and radially by a threaded connection  6  formed between a threaded drive member  4  and a threaded stem element  5 . The jaws  7  can shift axially and radially in the chuck body  3  but cannot move angularly relative to it or to the drive member  4 . On the other hand, the stem element  5  can as described below rotate relative to the chuck body  3  but not move axially or radially therein or can be rotationally fixed to the chuck body  3 . 
     In addition as also shown in  FIG. 3 , a planetary-gear transmission has a sun gear  10  that is rotatable about the axis A by the motor  37 , five planet gears  12  meshing radially inward with the sun gear  10  and radially outward with a ring gear  13  that is rotationally fixed on the housing  1  but as described below limitedly axially displaceable thereon. The planet gears  12  are mounted on a planet carrier  11  rotatable about the axis A and connected to a drive sleeve  8  rotationally coupled to the stem element  5 . 
     The threaded stem element  5  is formed in two relatively nonrotatable parts from a threaded sleeve  14  and an axially displaceable coupling rod  15  both centered on and rotatable about the axis A with the rod  15  inside the sleeve  14 . The sleeve  14  is connected by the screwthread  6  to the drive member  4  and is axially nondisplaceable in the chuck body  3 . The sleeve  14  and rod  15  are rotationally coupled to each other, for instance by complementary polygonal cross sections. The sleeve  14  and rod  15  are rotatable in the tubular drive spindle  2  that has a radially enlarged front end  16  against which the sleeve  14  is axially rearwardly braced. The coupling rod  15  has at its rear end a coupling spur gear  17 , and the tubular drive spindle  2  has end immediately thereadjacent at its rear end a similarly toothed spindle spur gear  18 . 
     The planetary-gear transmission  9  and the drive sleeve  8  are axially displaceably relative to the housing  1 , the spindle  2 , the chuck body  3 , and the stem element  5 . An adjusting sleeve  22  is externally carried and axially shiftable on the housing  1  and is coupled to the gear transmission  9  and sleeve  8  to axially shift them relative to the housing  10 . To this end, radially extending screws  23  couple the adjusting sleeve  22  to the ring gear  13 . 
     The housing  1  is provided with a cover cap  24  axially just behind the chuck body, on the side of the power drill facing away from the motor, and releasably connected to the housing. Bearings  25  are provided between the drive spindle  2  and the housing  1 . 
     The drive sleeve  8  is formed with an internal toothing or gear  19  complementary to the gears  17  and  18  and axially long enough to accommodate both of them. Immediately therebelow, the ring gear  13 , which is axially limitedly shiftable in the housing  1  with the rest of the planetary transmission  8  but not rotatable on the housing  1 , is also formed with a ring of internal teeth  38  meshable with the teeth of the gear  17 . The transmission  8  and the gear teeth  19  and  38  can move axially between a rear position shown in  FIG. 1  with the gear  17  meshing with the teeth  19  and the gear  18  meshing with the teeth  38 , and a front position shown in  FIG. 2  with both of the gears  17  and  18  meshing with the teeth  19 . 
     In  FIG. 1 , the structure is shown in the tightening position in which the internal gear teeth  19  of the drive sleeve  8  is in mesh with the coupling spur gear  17  and the spindle spur gear  18  is meshed with the teeth  38  of the nonrotating ring gear  13 . Here, the force of the motor  37  is transmitted as usual via a machine spindle to the sun gear  10  of the planetary-gear transmission  9 . This drives the planet gears  12  mounted on the planet carrier  11  that roll on the ring gear  13  rotationally fixed to the housing  1 , thereby rotating the drive sleeve  8 . For its part, the drive sleeve  8 , which is rotationally connected to the planet carrier  11 , transmits the force to the coupling spur gear  17 , as a result of which the coupling rod  15  and the threaded sleeve  14  are both rotated. As the spindle spur gear  18  and therefore the tubular drive spindle  16  are rotationally connected via the ring gear  13  to the housing  1 , this enables relative rotation of the threaded sleeve  14  relative to the tubular drive spindle  16 , and the threaded stem element  4  is displaced by the threaded connection  8  axially forward, i.e. in a direction away from the motor  37 , or axially backward, taking with it the jaws  7 . Depending on the direction of rotation of the sun gear  10 , the chuck is tightened or loosened. 
       FIG. 2  shows the embodiment in the drilling configuration in which the drive sleeve  8  and the planetary-gear transmission  9  are moved axially forward so that the coupling spur gear  17  and the spindle spur gear  18  both mesh with the internal gear teeth  19  of the drive sleeve  8 . Here too, the force of the motor is transmitted to the sun wheel  10  of the planetary-gear transmission  9 . This drives the planet gears  12  mounted on the planet carrier  11  that roll on the ring gear  13  that is rotationally connected to the housing  1 . Here, the drive sleeve  8  is displaced axially forward by the displacement of the adjusting sleeve  22 . The drive sleeve  8  is driven by the planetary-gear transmission  9  and is now rotationally connected to the coupling rod  15  and to the tubular drive spindle  16  by engagement of the coupling spur gear  17  and the spindle spur gear  18  with the internal gear teeth  19  of the drive sleeve  8  so that the force of the motor is transmitted directly to the coupling rod  15  and the tubular drive spindle  16 . This prevents relative rotation of the threaded sleeve  14  relative to the tubular drive spindle  16  and the displacement of the jaws  7 . 
     A further preferred embodiment is shown in  FIG. 4  to  FIG. 6 . Here, the drive sleeve  8  is fixed by snap rings  40  to the coupling spur gear  17 , and the coupling rod  15  has an external crown gear  20 . For its part, the tubular drive spindle  16  has an internal spindle crown gear  21 . 
       FIG. 4  shows the embodiment in the tightening position, in which the crown gear  20  provided on the coupling rod  15  is not engaged with the spindle crown gear  21  of the tubular drive spindle  16 . In this embodiment, the motor  37  rotates the sun gear  10  of the planetary-gear transmission  9  to drive the planet gears  12  mounted on the planet carrier  11  that roll on the ring gear  13  rotationally connected to the housing  1 . The planet carrier  11  is rotationally connected to the drive sleeve  8  and therefore to the coupling rod  15  that as a result is driven by the motor  37 , regardless of the axial position of the transmission  9  and sleeve  8 . The tubular drive spindle  16  engages with the teeth  39  of the ring gear  13  that is rotationally connected to the housing  1 . The adjusting sleeve  22  is displaced axially backward so that the crown gear  20  of the coupling rod  15  is not engaged with the spindle crown gear  21 . As a result, only the coupling rod  15  is driven by the motor  37  and not the tubular drive spindle  16 . In this tightening position, relative rotation is possible between the tubular drive spindle  16  and the threaded sleeve  14 , so that, in this embodiment, the jaws  7  are also displaced by the axial displacement of the threaded drive member  4 . 
     On the other hand, in  FIG. 5 , the power drill is shown in the drilling configuration where the crown gear  20  meshes with the spindle crown gear  21 . In this configuration, the motor  37  rotates the sun gear  10  of the planetary-gear transmission  9  to drive the planet gears  12  that roll on the ring gear  13  rotationally connected to the housing  1 . The adjusting sleeve  22  is now displaced axially forward, as a result of which the planetary-gear transmission  9  and the drive sleeve  8  with the coupling rod  15  are also displaced axially forward, and the ring gear  13  and the tubular drive spindle  16  are disengaged. In this drilling configuration, the crown gear  20  of the coupling rod  15  is engaged with the spindle crown gear  21 , as a result of which the force of the motor  37  is transmitted to both the coupling rod  15  and to the tubular drive spindle  16 . Relative rotation between the tubular drive spindle  16  and the threaded sleeve  14  is prevented. 
       FIG. 6  shows that, in this illustrated embodiment, the drive sleeve  8  also has internal gear teeth  19 . In addition, the adjusting sleeve  22  does not have to fully surround the power drill. 
     A further preferred embodiment is shown in  FIGS. 7  to  FIG. 11  where the chuck body  3  is a sleeve  26  and has two axially spaced rings  27  of internal gear teeth. A spindle rod  28 , which can be driven by the motor  37  and that in the illustrated embodiment has a socket  32  for a drive tool, is axially displaceably guided in the chuck body  3 . In this embodiment, the drive sleeve  8  takes the place of the ring gear  13  engaged with the planet gears  12 . 
       FIG. 7  shows the power drill in the tightening position, in which a ring of crown-gear teeth  29  on the spindle rod  28  is engaged with a planet gear  12  and not engaged with the chuck crown gear  27 . A spring  30  that supports the spindle rod  28  and forces the power drill into the drilling configuration is provided between the chuck sleeve  26  and the spindle rod  28 . A driver ring  31  that interacts with an adjusting element  23  associated with an adjusting sleeve  22  coaxially surrounds the spindle rod  28 . Usually a control cam is formed between the housing  1  and the adjusting element  23  and/or the adjusting sleeve  22 , thus enabling the spindle rod  28  to be easily displaced manually. 
     In this embodiment, the motor  37  is directly connected to the spindle rod  28 , which for its part drives the planet gears  12  that roll on the ring gear  13 . The planet gears  12  are fixed in the chuck body  3  so that the ring gear  13  rotates as a result of their being driven. The ring gear  13  shown here is rotationally connected to the threaded stem element  5 . The spindle crown gears  29  are not engaged with the chuck crown gears  27 , thus enabling rotation of the spindle rod  28  relative to the rotatably fixed chuck body  3 . In this tightening position, the threaded stem element  5  is therefore driven by the motor  37  via the connection with the ring gear  13  and the planet gears  12  to drive the ring gear  13 . This enables the jaws  7  in the fixed chuck body  3  to be displaced. 
     The power drill from  FIG. 7  is shown in  FIG. 8  in the drilling configuration where each of the spindle rod crown gears  29 , two of which are provided here, is engaged with a respective one of the chuck crown gears  27 . Furthermore, a bearing  25  is provided between the housing  1  and the chuck sleeve  26  in these embodiments. The spindle rod  28  is displaced axially rearward by the adjusting sleeve  22 , as a result of which the motor  37  rotates the spindle rod  28  and the chuck body  3  by engagement of the chuck crown gears  27  with the spindle rod crown gears  29 . In the illustrated embodiment shown, the spindle rod  28  is also rotating with the planet gears  12 , which however, in this drilling configuration, for their part no longer roll on the ring gear  13  however, as the ring gear  13  and the planet gears  12  are carried along with the rotation of the chuck body  3 . Rotation of the chuck body  3  relative to the threaded stem element  5 , which effects the displacement of the jaws  7 , is prevented. 
       FIG. 9  shows that the spindle rod crown gear  29  as sun gear  10  is engaged with a planet gear  12  that for its part is engaged with the drive sleeve  8  in the form of ring gear  13 . 
       FIG. 10  shows that no part of the spindle rod  28  is engaged with the chuck crown gear  27  shown here, enabling the spindle rod  28  to be rotated relative to the chuck sleeve  26 . 
       FIG. 11  shows that the spindle crown gear  29  is engaged with the chuck crown gear  27  and therefore, in the drilling configuration, the chuck sleeve  26  is carried along when the spindle rod  28  rotates. 
       FIG. 12  shows that the driver ring  31  of the illustrated embodiment shown has a ring  33  of internal gear teeth and another ring  36  of external gear teeth. In addition, gear teeth  34  are formed on the housing  1 . In the drilling configuration, the internal gear teeth  33  engage with the chuck-body teeth  35  and the external gear teeth  36  with the housing gear teeth  34 . As a result, the chuck body  3  or chuck sleeve  26  is fixed. As well as gear teeth, other rotatably fixed connections between the above-mentioned parts are also conceivable.