Patent Abstract:
A hand power tool has a tool holder with a base body; a drive part; at least one locking body for connecting the base body of the tool holder with the drive part; a securing body which radially fixes the at least one locking body in an engaging position; an actuating element operative for unlocking the tool holder and guiding the securing body to a position which radially releases the locking body, the base body in a locking position surrounding at least a part of the drive part.

Full Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to hand power tools. 
     German patent document DE 196 21 610 A1 discloses a hand power tool with a removable tool holder. The hand power tool has a spindle sleeve, in which a base body of the tool holder is insertable and lockable by locking bodies. The locking bodies are non releasably held in the spindle sleeve and are radially covered in a locking position by a securing body. For removing the tool holder, the securing body is displaceable by an actuating sleeve axially to a position which radially releases the locking bodies. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a hand power tool of the above mentioned general type, which is a further improvement of the existing hand power tools. 
     More particularly, it is an object of the present invention to provide a hand power tool, in which a tool holder is connectable by its base body releasably with a drive part through at least one locking body. 
     In accordance with the invention, the locking body in its engaging position is radially fixable by a securing body, which is guided by an actuating element for unlocking the tool holder to a position which radially releases the locking bodies. 
     It is proposed that the base body in its locking position is surrounded by at least a part of the drive part. An anvil can form with the drive part gap seal, which protects the drive unit of the hand power tool from dirt. A low wear can be therefore obtained and damages during insertion of the tool can be avoided. Furthermore, the locking bodies can be mounted on the base body of the tool holder and can be easily replaced or changed with the tool holder when needed. 
     In accordance with a further embodiment, it is proposed that in the unlocked condition a component holds the locking body in its unlocking position. The tool holder can be easily mounted on the drive part without displacing the locking body. Furthermore, with the component, a recess of the locking body is preferably radially inwardly closed, and a dirtying in the region of the locking body can be avoided, in particular in the dismounted condition. The locking bodies can be loaded in its unlocking position in the locking direction, and thereby an advantageous acoustic and/or optical signal can be provided which signals to a consumer a reliable connection between the tool holder and the drive part. Furthermore, by the position of the locking body, simply a signal can be released through which an energy supply of the hand power tool is controllable. With the not completely mounted tool holder, the energy supply can be interrupted, a damage to the tool can be reliably prevented, and the user can be protected. 
     Advantageously, several recesses can be arranged over the periphery of the drive part as locking bodies in the base body. Thereby a small turning angle can be obtained during joining the tool holder and the drive part. With the high number of the recesses, the wear of several recesses can be avoided, so that a greater service life can be obtained. 
     For providing automatic turning of the tool holder to the proper location during fitting of the tool holder on the drive part, the base body and the drive part are advantageously connected through at least one set of teeth in the peripheral direction. In the axial direction they can have reduced contact surfaces, or in other words inclined and/or rounded contact surfaces. The teeth can have a flat contact surfaces in the axial direction and can be guided by hand to a proper position. 
     Advantageously the base body and the drive part are connected in a peripheral direction via at least one roller mounted on the base body. Instead of the locking body, advantageously the roller can be used as an abutment for the locking bodies in the dismounted condition of the arrestable component, and the locking bodies can be covered in their unlocking position completely by the component in a structural simple manner. Furthermore, a standard component can be used as a roller, and the rotary transmission can be performed in a cost favorable manner. 
     In accordance with a further embodiment of the present invention, it is proposed that at least one locking body is used for torque transmission. Additional components, as well as structural space, weight and mounting expenses can be saved, or available rotary transmission element can be supported in its function. For example, the locking body formed as a sphere can be guided in a recess formed as a spherical calotte so that a favorable force transmission can be provided. In order to obtain a small surface pressure, the locking body, in addition to being formed as a sphere, can be also formed with different shapes, for example roller-shaped parallelopiped-shaped, etc. A high torque can be transmitted with a simultaneously reduced wear and higher service life. 
     It is further proposed that the base body has a stepped inner contour to the drive part, and the drive part has a corresponding outer contour. A good guidance and thereby true running are provided by the cylindrical guiding diameter at the front and at the rear receiving region. 
     The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view showing a section of a hammer drill with a tool holder in accordance with the present invention; 
     FIG. 2 is a view showing a section of the inventive tool holder taken along the line II—II in FIG. 1; 
     FIG. 3 is a view showing an inventive tool holder of FIG. 1 in the engaged condition; 
     FIG. 4 is a view showing a variant of FIG. 1, with rollers for rotation of the tool holder; 
     FIG. 5 is a view showing a section of the inventive tool holder, taken along the line V—V in FIG. 4; and 
     FIG. 6 is a view showing a tool holder of FIG. 4 in the engaged condition. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows an unlocked tool holder  12  of a hammer drill. It is releasably connectable with its base body  14  to a drive part  16  through three locking bodies  18 ,  42 ,  44  shown in FIG.  2 . In their engaging position, the locking bodies  18 ,  42 ,  44  are readily fixable by a securing ring  20 . The securing ring is guidable via an actuating sleeve  22  to a position which radially releases the locking bodies  18 ,  42 ,  44 . 
     The drive part  16  has a spindle sleeve  110 , in which an anvil  74  is guided. The spindle sleeve  110  is mounted via a clamping ring  108  in a hammer tube  106 . The spindle sleeve  110  and the hammer tube  106  can be formed of one piece with one another. 
     In accordance with the present invention, the base body  14  of the tool holder  12  in a locking position surrounds the spindle sleeve  110  shown in FIGS. 1,  2  and  3 . The locking bodies  18 ,  42 ,  44  are arranged in the base body  14  and held in their unlocking position via a component formed as a securing sleeve  24 . The securing sleeve  24  is loaded with a helical spring  112  in direction of the drive part  16 . It is supported with one end on the locking bodies  18 ,  42 ,  44  and fixes them in their radially outer position. 
     The securing ring  20  has a first region  118  with a smaller inner diameter and a second region  122  with a greater inner diameter. A transition between the diameters is performed through an incline  120 . The securing ring  20  abuts radially outwardly against the actuating sleeve  22 . In the unlocking position, the locking bodies  18 ,  42 ,  44  act as an abutment for the securing ring  22  which is loaded in direction of the drive part  16  by a helical spring  124 . The helical spring  124  is supported with one end via a ring  126  and a clamping ring  128  against the base body  14 . The locking bodies  18 ,  42 ,  44  are loaded radially inwardly in their locking directions  28 ,  60 ,  62  via an incline  120  formed of the safety ring  20 . 
     The base body  14  and the drive part  16  are connectable through a set of teeth  30  in the peripheral direction. It has contact surfaces  32  which are narrowed or inclined in an axial direction. The spindle sleeve  110  of the drive part  16  has spherical-calotte-shaped recesses  82 , for receiving the locking bodies  18 ,  42 ,  44  in their engaging position. Thereby they are usable for the torque transmission. Several recesses  82  are arranged over the periphery of the spindle sleeve  110  as locking bodies  18 ,  42 ,  44 , in the base body  14 . Furthermore, the base body  14  has an inner contour  38  which is stepped to the spindle sleeve  110 , and the spindle  110  forms a gap seal  80  with the anvil  74 . 
     When the base body  14  is fitted on the spindle sleeve  110 , the teeth  30  with their contact surfaces  32  which face in the axial direction and are narrowing, lead the base body  14  automatically in the correct locking position to the corresponding recesses  100  of the spindle sleeve  110 . When the locking bodies  18 ,  42 ,  44  are located over the recesses  82 , the securing sleeve  24  is supported against an abutment  134  of the spindle sleeve  110  and displaced against the spring force of the helical spring  112  in direction  114 , so that the locking bodies  18 ,  42 ,  44  are radially inwardly released. The locking bodies  18 ,  42 ,  44  are pressed by the helical spring  124  via the incline  120  of the safety ring  20 , radially inwardly into the recesses  26 ,  34 ,  36 . 
     The helical spring  124  displaces the safety ring  20  with the region  118  radially over the locking bodies  18 ,  42 ,  44  and secures them in their locking positions. The securing ring  20  is supported in direction of the drive part  16  via a clamping ring  104  which is mounted in the actuating sleeve  22 , through the actuating sleeve  22 , and through a projection  88  formed on the actuating sleeve  22 , against the ring  126 . The ring  126  is supported via a projection  132  against the base body  14 . FIG. 3 shows the tool holder  12  which is fitted on the drive part  16  and engaged. 
     A tool receptacle  116  for the tool with a grooved shaft is arranged in the base body  14 . The tool receptacle  116  has a radially displaceable locking body  19  formed as a locking ball  94 . It is guidable in the grooves of the tool which are closed on the shaft end, and is held in its locking position by a locking ring  98  which is axially movable within certain limits and by a holding plate  96 . The locking ring  98  is loaded via the holding plate  96  with a spring  84  in direction of its locking position. In the locking position of the locking ball  94  the locking ring  98  radially overlaps the locking ball  94  and the holding plate  96  secures the locking ball  94  with a projection in an axial direction. 
     During insertion of the tool, the locking ball  94  is displaced by the shaft end of the tool in a longitudinal slot  90  in an insertion direction. The holding plate  96  is displaced on its projection over the locking ball  94  against the spring  84 . Between the locking spring  98  and the holding plate  96  there is a free space, in which the locking ball  94  can be radially outwardly deviated. The tool can be therefore inserted. Subsequently, the pre-stressed spring  84  displaces the holding plate  96  to its initial position and presses the locking ball  94  in the groove of the tool. For protecting the tool receptacle  116  from dirt, a rubber cap  86  with sealing lips  76 ,  78  is mounted in the front region of the base body  14 . 
     For removing the tool, an actuating sleeve  130  displaces the locking ring  98  against the holding plate  96  and against the spring  84  which loads the holding plate  26 . Therefore the locking balls  94  can deviate radially outwardly and the tool can be removed. After this, the spring  84  presses the holding plate  26 , the locking plate  96 , the locking ring  28  and the locking ball  94  back to their initial positions. 
     The connection between the tool holder  12  and the drive part  16  is separated, by displacing the actuating sleeve  22  in direction  114  of the tool receptacle  116 . Via the clamping ring  104  which is mounted on the actuating sleeve  22 , the securing ring  20  is axially displaced in direction  114  of the tool receptacle  116  against the spring force of the helical spring  124 , until the securing ring  20  with its second region  122  radially outwardly releases the locking bodies  18 ,  42 ,  44 . 
     The securing sleeve  24  which is loaded by the helical spring  112  presses against the abutment  134  of the spindle sleeve  110  and supports the pulling out of the tool holder  12 . The locking bodies  18 ,  42 ,  44  during the axial movement of the tool holder  12  are pressed radially outwardly by the calotte-shaped recesses  82  and held in their radially outer position by the securing ring  20 . 
     The connection between the drive part  16  and the tool holder  12  is opened, and the locking bodies  18 ,  42 ,  44  are fixed so that they can not be lost. The spring-loaded securing ring  20  abuts with its incline  120  against the locking bodies  18 ,  42 ,  44  and loads them in their locking directions  28 ,  60 ,  62 . 
     FIGS. 4-6 show further embodiment of the hammer drill with a tool holder  72  and a drive part  50 . Substantially the same remaining parts are identified with the same reference numerals. The differences between the embodiment of FIGS. 4-6 and the embodiment of FIGS. 1-3 are described herein below. With respect to the remaining functions and features, the description of FIGS. 1-3 can be utilized in this embodiment as well. 
     In contrast to the embodiment shown in FIG. 1, the tool holder  72  has a base body  52  which is connectable in a peripheral direction with a spindle sleeve  102  of the drive part  50 , instead of the teeth  30  through three rollers  54 ,  56 ,  58  which are mounted on the base body  52 . The locking bodies  18 ,  42 ,  44 , and the rollers  54 ,  56 ,  58  are arranged in the recesses  46 ,  48 ,  64 ,  66 ,  68 ,  70  of the base body  52  as shown in FIG.  5 . The recesses  66 ,  68 ,  70  of the rollers  54 ,  56 ,  58  are radially inwardly narrowed, and thereby the rollers  54 ,  56 ,  58  are limited radially inwardly with respect to their movement. The rollers  54 ,  56 ,  58  are held radially outwardly by a ring  10 . 
     The locking bodies  18 ,  42 ,  44  are held in their radially outer position or unlocking positions via the securing ring  24 , which is loaded via a helical spring  92  in direction of the drive part  50  and is supported on the rollers  54 ,  56 ,  58 . The securing sleeve  24  closes the recesses  26 ,  34 ,  36  of the locking bodies  18 ,  42 ,  44  radially inwardly. 
     It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above. 
     While the invention has been illustrated and described as embodied in hand power tool, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

Technology Classification (CPC): 8