Patent Publication Number: US-2011049817-A1

Title: Tool holder

Description:
This claims the benefit of German Patent Application DE 10 2009 028 890.2, filed Aug. 26, 2009 and hereby incorporated by reference herein. 
     FIELD OF THE INVENTION 
     The present invention relates to a tool holder for a power tool of the type known from British patent application GB 232 61 23 A1. A tool that is in the tool holder is unlocked by moving an actuation sleeve against a coil spring. No dust or drillings can penetrate into the areas where the actuation sleeve is connected to the housing parts of the power tool and of the tool holder. 
     SUMMARY OF THE INVENTION 
     An object of the present invention includes sealing the actuation sleeve. The present invention provides a tool holder for a hammer drill having an external cover and an axially movable actuation sleeve for unlocking an inserted tool. The end area of the actuation sleeve on the tool side overlaps an end area of the cover on the machine side. A plastic coating made of an elastic material is spray-coated onto the end area of the actuation sleeve on the tool side and/or onto the end area of the cover on the machine side. The plastic coating is arranged at least partially between the actuation sleeve and the cover. This makes it possible seal the actuation sleeve and a hollow space that is surrounded by the sleeve and located at one end on the tool side. 
     One embodiment has a one-piece sealing ring whose radially outer section is made of an elastic plastic, and whose radially inner section is made of a brittle plastic, whereby the radially outer section touches an inner surface of the actuation sleeve. The one-piece sealing ring made of two different plastics has proven to be very effective for sealing purposes and to be durable. The one-piece structure of the sealing ring, that is to say, the integral joining of the material of the inner and outer sections, reduces the number of boundary surfaces in comparison to cases where conventional sealing rings are used near the actuation sleeve. The hard inner section mechanically supports the outer section. A cuff that protrudes perpendicularly with respect to an axis of a tubular base can be attached to said base and the radially inner section of the sealing ring can lie flat against a protruding area of the cuff. 
     One embodiment has a coil spring that is arranged coaxially inside the actuation sleeve, whereby the end of this spring on the machine side is supported on the radially inner section of the sealing ring. The tool holder can have locking elements for a tool upon which a force is exerted by the coil spring. The coil spring that is used for the locking mechanism holds the sealing ring in place. This advantageously allows the number of components of the tool holder to be kept to a minimum. 
     One embodiment provides that an end of the coil spring on the tool side axially exerts force on the actuation sleeve in the direction of an end of the tool holder on the tool side. The actuation sleeve can have a contact surface facing radially inwards against which the end of the coil spring on the tool side rests. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The description that follows explains the invention on the basis of examples of embodiments and figures. The figures show the following: 
         FIG. 1 : a hammer drill; 
         FIG. 2 : a tool holder of the hammer drill. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a hammer drill  10  and a detailed view of an embodiment of a tool holder  11 . A tubular base  12 , as shown in  FIG. 2 , of the tool holder  11  for holding a tool is provided with a receiving opening  14  at one end  13  on the tool side. The shaft  15  of a tool  16 , for instance, a drill, can be inserted through this receiving opening  14  lengthwise into the base  12 . 
     The base  12  has lateral openings  17  through which the locking elements  18  engage from the outside into axially closed lengthwise grooves  19  in the shaft  15  of the tool  16 . The locking elements  18  shown by way of an example are configured as pawls that can be moved in the axial direction  20 . 
     In its basic position, the tool  16  is locked in the tool holder  11 . A force is exerted onto the pawls  18  by a coil spring  21  in the direction of the receiving opening  14 . In the position of the pawl  18  when it is advanced towards the receiving opening  14 , the surface  22  of the pawl facing outwards in the radial direction is in contact with a link  23 . 
     The tool  16  can be removed from the tool holder  11  in that a user pushes an axially movable actuation sleeve  24  away from the receiving opening  14 . The actuation sleeve  24  has a contact surface  25  that is arranged between the pawls  18  and the coil spring  21  in the axial direction and upon which a force is exerted by the coil spring  21 . Moving the actuation sleeve  24  and compressing the coil spring  21  cause the pawls  18  to be released from the link  23 . The pawls  18  can be swiveled radially outwards around a point of rotation  38 , thereby releasing the tool  16 . 
     The hammer drill  10  has a machine housing  26  for the drive components. The tool holder  11  is surrounded by a cover  27 . The movable actuation sleeve  24  is partially arranged between the machine housing  26  and the cover  27 , so that the user can grasp the actuation sleeve  24  from the outside. In the embodiment shown, the coil spring  21  is located inside the actuation sleeve  24  in the axial direction. A front section  34  of the actuation sleeve  24  facing in the direction of the receiving opening  14  is arranged radially inside the cover  27 . An edge  36  of the cover on the machine side is made of a soft elastic plastic having, for instance, a Shore A hardness ranging from 50 to 95. The soft edge can be spray-coated onto the cover  27 , the rest of which is made of hard plastic. The soft plastic coating  36  touches the front section  34  of the actuation sleeve  24  and ensures a dust-proof closure. As an alternative, a soft plastic coating that touches the cover  27  can be spray-coated onto the front section  34  of the actuation sleeve  24 . 
     A dust seal on the end of the actuation sleeve  24  on the machine side comprises a sealing ring  28 . The sealing ring  28  is pushed over the base  12  and is arranged between the machine housing  26  and the coil spring  21  in the axial direction. The coil spring  21  is in contact with a radial inner section  29  of the sealing ring  28 . The sealing ring  28  is supported on a cuff  32  that is welded onto the base  12  or that is in positive contact with a conically expanding section of the base  12  and that is clamped by the coil spring  21 . 
     A rim  33  of the cuff  32  is positioned perpendicularly to the axis of the base  12 . On the machine side, the radial inner section  23  lies flat on the rim  33 . When the coil spring  21  presses the sealing ring  28  against the cuff  32 , this area is sealed so as to be dust-proof. 
     A radially outer section  30  of the sealing ring  28  is made of a soft, elastic plastic. The soft plastic of the outer section  30  is spray-coated onto the inner section  29 . The outer section  30  touches the inside  31  of the actuation sleeve  24  and ensure a dust-proof seal.