Patent Publication Number: US-6213695-B1

Title: Automatic spindle arresting device

Description:
FIELD OF THE INVENTION 
     The invention relates to an automatic spindle arresting device, for hand tools especially for drill screwdrivers, angle grinders and the like. 
     BACKGROUND OF THE INVENTION 
     The DE 297 15 257 U1 discloses a driving device for a spindle of a motor-driven, hand-guided working tool, especially a drilling or impact screwdriver, with a driving part, which is connected with the spindle, so that there cannot be mutual rotation, and which can be coupled in both directions of rotation of the spindle over clamping bodies in the form of rollers of a free-wheel with a ring, which is fastened to the housing, with a driving part, which is disposed equiaxially to the spindle and has unlocking elements, which interact with the rollers, which act as clamping bodies and, when the driving part is driven, release the clamping bodies so that the driving part is uncoupled from the ring fastened to the housing and can be rotated, and with torque-transmnitting driving surfaces being provided at the driving part and the driving part for driving the spindle by motor, in the neutral position of the driving part the distance between the driving surfaces being larger than the distance between the unlocking element and the assigned clamping body. In the case of this driving device, the driving part has claws, which are spatially separated from the unlocking element and protrude into the driving part, the surfaces of the claws and of the driving openings, which face one another in the respective direction of rotation, forming the torque-transferring driving surfaces. For the driving device, a total of six clamping bodies in the form of balls are provided. The construction of such an automatic spindle arresting device or driving device is very expensive. As a result, the installation is very expensive and costly since, aside from the driving part and the driving part, six clamping bodies must be installed. Considering the large number of moving parts, malfunctions, breakdowns and defects in the spindle arresting device cannot be excluded. 
     Furthermore, the EP 0 761 350 A1, for example, also discloses a spindle arresting device, the construction of which is expensive. 
     Furthermore, DE 44 45 597 A1 and DE 44 45 598 A1 disclose spindle 1 arresting devices in the form of adapters. These also have a relatively complicated construction. 
     OBJECT OF THE INVENTION 
     It is an object of the invention to develop an automatic spindle arresting device for hand tools of the generic type further in such a manner, that they comprise the least possible number of individual parts, can be produced in a simple manner and, as far as possible, are not susceptible to breakdowns and are resistant to wear. 
     SUMMARY OF THE INVENTION 
     This objective is accomplished pursuant to the invention for an automatic spindle arresting device for hand tools of the type described above by the distinguishing features of claim  1 . 
     Owing to the fact that the unlocking elements comprise one or more control curves disposed at the driving part and one or more control cams sliding along the control curves by a rotational movement of the driving part in such a manner, that the latching part and the arresting part can be uncoupled by axially shifting the latching part and/or the arresting part, an automatic spindle arresting device is made possible, which functions reliably, has a simple structure and therefore is manufactured easily, and is resistant to wear. 
     As far has the construction of the arresting part, the driving parts and the latching part is concerned, different constructions are conceivable in principle. 
     In the case of an advantageous embodiment, provisions are made so that the arresting part is disposed attached to the housing, provided with openings, and disposed concentrically to the spindle, it being possible to engage locking cams, disposed on the than latching part, by shifting the latching part axially. Such an arresting part, which is provided with openings, can be produced simply and installed easily in the housing. 
     Moreover, provisions can also be made so that the arresting part is formed in one piece with the housing. In this case, additional installation of the arresting part can be omitted completely. 
     Preferably, moreover, provisions are made so that the openings in each case are disposed offset by the same angle in the arresting part. This enables the spindle to be arrested quickly in both direction of rotation 
     Likewise, provisions are advantageously made so that the arresting cams and the control cams are disposed in each case consecutively on the latching part, being offset by the same angle as the openings in the arresting part. 
     The arresting part advantageously is disposed, so that it can be shifted axially on the spindle against a restoring force of a restoring spring, acting in the direction of the arresting part. By means of these restoring springs, it is ensured that, when the hand tools is at rest, the arresting cams, disposed on the latching part, engage the openings of the arresting part. 
     In the case of a different, advantageous embodiment, which can be used especially with hand tools with a planetary gearing and a torque coupling, provisions are made so that the arresting between the housing and the arresting part is brought about by a latching part assigned to the housing. 
     The arresting part is, for example, a planet carrier of a planet gearing. 
     The driving element preferably is an internal gear of the planet gearing. 
     Advantageously, provisions are made so that the openings are disposed at always the same angle in the planet carrier. By these means, rapid arresting is made possible in both direction of rotation of the spindle. 
     The arresting cams and the control cams are disposed consecutively at the latching part, being offset by the same angle as the openings in the planet carrier. 
     The axially displaceable latching part advantageously is disposed at the housing so that that it cannot rotate relative to the housing and, moreover, against a restoring force of a restoring spring, acting in the direction of the planet wheel. By means of these restoring springs, it is ensured that the arresting cams, disposed on the latching part, engage the openings of the planet wheel, acting as arresting part, when the hand tool is stopped. 
     In the case of a hand tool machine, which has a torque coupling, provisions are advantageously made so that the internal gear is part of a torque coupling, the periodicity of the clamping bodies of the torque coupling corresponding to the periodicity of the control paths or control cams. 
     The control paths, disposed on the driving part, can be limited by a unilateral stop. In this way, a precise disengagement of the arresting part from the driving part and the reverse are realized and an unwanted, renewed engagement of these two parts is avoided. 
     The control paths themselves can be constructed in different ways. One embodiment, which is particularly advantageous with respect to its manufacture, makes provisions so that the control paths have a basic surface, an essentially flat inclined surface with an inclination disposed in the axial direction and a flat plateau surface, which adjoins the inclined surface and extends perpendicularly to the axial direction. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further advantages and distinguishing features are the object of the following description as well as of the diagrammatic representation of a few examples. In the drawing 
     FIG. 1 shows a partially truncated partial sectional representation of the front part of a hand tool machine with an inventive, automatic spindle arresting mechanism, 
     FIG. 2 shows a representation of the arresting part and of the latching part, 
     FIG. 3 shows a side view of the driving part, the latching part and the arresting part, shown in FIG. 1, 
     FIG. 4 shows a plan view of the latching part shown in FIGS. 1 to  3 , 
     FIG. 5 shows a partially truncated partial sectional representation of a drilling screw driver with a further embodiment of an inventive spindle arresting device and 
     FIG. 6 shows a detailed sectional representation as well as plan views of the latching part, the power take-off part and the automatic arresting part of the automatic spindle arresting device shown in FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A hand tool, such as a drill, the front part of which is shown in FIG. 1, comprises a housing  10 , in which a spindle  20  is rotatably mounted. The spindle  20  is driven by a drive shaft  30  of a (not shown) motor over an internal gear  34 , which is constructed as driving part and connected to the spindle  20  so that there cannot be any relative rotation. For this purpose, the driving shaft  30  of the motor is provided at its front end with gearing  32 , which engages the gearing of the internal gear  34 . 
     Aside from the internal gear  34 , an automatic spindle arresting device comprises an arresting part  40 , which is fastened to the housing and is in the form of an arresting disk, and a latching part  50 , which can be shifted axially, against the restoring force of a restoring spring  60 , onto multi-sided, beveled sliding surfaces  22  of the spindle  20  in the region of the latching part  50 . The spindle  20  is intended to accommodate a (not shown) tool, such as a drill, which can be fastened by means of a rotatable clamping element  26  in a spindle opening. 
     The mode of functioning of the automatic spindle arresting device, formed from the internal gear  34 , the arresting part  40  and the latching part  50 , is described in the following in conjunction with FIGS. 2,  3  and  4 . 
     When the drill is not running, arresting cams  52 , disposed on the latching part  50 , engage openings  42 , which are provided in the arresting part  40 , which is constructed as an arresting disk, as shown in the upper half of FIG.  1  and in FIG.  2 . The openings  42  of the arresting part  40 , as well as the locking cams  52  on the latching part  50  are disposed offset periodically to one another by the same, preferably small angles, by means of which rapid engagement of the automatic spindle arresting device becomes possible when the spindle  20  is rotating in its two directions of rotation. 
     In order to bring about the normal operating state, that is, a drilling or screwdriving operation of the hand tool, control cams  54 , which are disposed on the latching part  50 , slide on control paths  38 , which are provided on the internal gear  34  on the side of the latter facing the latching part  50 , in such a manner, that the latching part  50  carries out an axial motion against the restoring force of the spring  60 , that is, away from the internal gear  34 . At the same time, the control paths  38  and the control cams  54  interact in such a manner, that an axial motion takes place to the extent that the arresting cams  52  are disengaged from the openings  42  in the arresting disk  40 . Such a disengagement occur in both of the directions of rotation of the spindle  20 . In this disengaged state, the spindle  20  is driven by die internal gear  34  by means of the drive shaft  30  and can rotate freely. This state is shown in FIG. 1 in the lower half. 
     In order to fasten a tool in the accommodating spindle, the latching part  50  is rotated by rotating at the clamping element  26 , the drive shaft  30  and, with that, the internal gear  34  being idle. Because of this rotational movement, the control cams  54 , which are disposed on the latching part  50 , slide on the control paths  38  along the internal gear  34 , until the arresting cams  52  engage the openings  42  in the arresting disk  40  and the spindle  20  is in the arrested state of a rest, so that, by rotating the clamping element  26 , opening and closing for fastening or removing a drilling tool is possible. 
     As shown particularly in FIGS. 2 and 3, the control paths  38 , disposed on the internal gear  34 , have a basic surface  38   a,  an essentially flat inclined surface  38   b,  with an inclination disposed in the axial direction, and a flat plateau surface  38   c,  which adjoins the inclined surface  38   b  and extends perpendicularly to the axial direction. Between adjacent control paths  38 , a stop cam  37  for the control cams  54  can be provided (FIG.  2 ). In this position, the axial displacement of the latching part  50  is a maximum. The arresting cams  52  are disengaged completely from the openings  42  of the arresting part  40 . 
     In the case of a further embodiment, which is shown in FIG. 5, an automatic spindle arresting device, which is used particularly for drilling screwdrivers, the driving element is constructed as an internal gear to  110  of a planetary gearing  100 . This internal gear  110  is driven in a known manner over a planet wheel  112 . 
     For this embodiment, the latching part  120  is assigned non-rotationally to the housing  10 , which is provided with the projections  130 , and, on its side facing the driving part  110 , has arresting cams  122  and control cams  124 , as can be seen, particularly, in FIG.  6 . 
     A planet carrier  140 , which acts as an arresting part and has openings  142 , which in each case are mutually offset by the same angle, is disposed concentrically to the internal gear  110 . The openings  142  and the arresting cams  122  are offset on the planet carrier  140  as well as on the latching part  120  in each case by the same angle to one another, so that an engagement of the arresting cams  122  of the latching part  120  in the openings  142  of the planet carrier  140  is possible. 
     On its front side, the internal gear  110  furthermore has guided paths for clamping bodies  114 , which are pressed against the restoring force of a restoring spring  115  onto one another or onto the guiding path  113 . A known torque coupling is realized in this way, the guiding paths  113  being disposed periodically on the internal gear  110  in such a manner that, depending on the adjustable force of the restoring spring  115 , torque transfer is possible. 
     The details of this torque coupling, which is not an object of the present invention, are not dealt with further. It is, however, an important distinguishing feature that the periodicity of the guiding paths  113  is identical with periodicity of control paths  116 , which are provided at the internal gear (see FIG. 6, left half). These control paths  116  comprise a flat, basic surface  116   a,  a flat surface of inclination  116   b  in the circumferential direction and a further flat plateau surface  116   c,  which is disposed axially offset relative to the basic surface  116   a  in the direction of the latching part  120 . 
     The function of the automatic spindle arresting device, shown in FIGS. 5 and 6, is described in the following. It should be noted that the not arrested state of the spindle is shown in each case in the upper half of FIGS. 5 and 6 and the arrested state, the state of rest, is shown in the lower half. 
     To bring about the normal operating state, that is, while drilling or screwing, the control cams  124  of the latching part  120 , guided axially displaceably on projections  130 , slide against the restoring force over the restoring spring  120  over the inclined surface  116   b  onto the plateau surface  116   c  and, in this way, bring about an axial displacement of the latching part  120 . The inclination of the inclined surfaces  116   b  is designed so that axial shifting of the latching part  120  results to such an extent, that the arresting cams  122  are disengaged from the openings  142  of the planet wheel  140 . In this state, which is shown in the lower half in FIG. 5, the spindle  20  is driven by the motor. 
     For clamping a tool while the motor is stationary, the latching part  120  is carried along by rotating at a clamping element  190  in such a manner, that the control cams  124  slide in the opposite direction from the plateau surface  116   c  over the inclined surface  116   b  onto the basic surface  116   a,  in which the arresting cams wanted to engage the openings  142  of the planet wheel  140 . In this state, the spindle  20  is arrested and tools, such as drills or screwing tools can be fastened, in seats provided for this purpose, by rotating the clamping element  190 .