Eccentric element for use in a hand-held power tool

Abstract

The invention refers to an eccentric element (10) configured for use in a hand-held power tool comprising a tool motor for driving a tool shaft (16), in particular for use in an orbital sanding or polishing machine. The eccentric element (10) comprises: an eccentric part (12) with a top surface (18) attachable to a distal end (22) of the tool shaft (16) or forming an integral part therewith so as to transmit a torque from the tool shaft (16) to the eccentric element (10) and to rotate the eccentric part (12) about a first rotational axis (28) upon activation of the tool motor, a bottom surface (32) to which a working element (30) of the power tool is releasably attachable in a manner freely rotatable about a second rotational axis (34), and a counterweight part (14) attached to the eccentric part (12). The eccentric part (12) and the counterweight part (14) are separate components and formed such that they enter into a mutual interlocking relationship upon attachment of the counterweight part (14) to the eccentric part (12), the interlocking relationship acting in at least one direction (76; 82; 86).(FIG. 3)

1 . Eccentric element ( 10 ) configured for use in a hand-held power tool having a tool motor for driving a tool shaft ( 16 ), including for use in an orbital sanding or polishing machine, the eccentric element ( 10 ) comprising:
 an eccentric part ( 12 ) with
 a top surface ( 18 ) releasably attachable or fixedly attached to a distal end ( 22 ) of the tool shaft ( 16 ) or forming an integral part of the tool shaft ( 16 ) so as to transmit a torque from the tool shaft ( 16 ) to the eccentric element ( 10 ) and to rotate the eccentric part ( 12 ) about a first rotational axis ( 28 ) of the eccentric part ( 12 ) upon activation of the tool motor, 
 a bottom surface ( 32 ) to which a working element ( 30 ) of the power tool, including a backing plate, a sanding plate or a polishing plate, is releasably attachable in a manner freely rotatable about a second rotational axis ( 34 ) of the eccentric part ( 12 ), and 
   a counterweight part ( 14 ) attached to the eccentric part ( 12 ), wherein   the eccentric part ( 12 ) and the counterweight part ( 14 ) are separate components and formed such that they enter into a mutual interlocking relationship upon attachment of the counterweight part ( 14 ) to the eccentric part ( 12 ), the mutual interlocking relationship acting in at least one direction ( 76 ;  82 ;  86 ).   
     
     
         2 . Eccentric element ( 10 ) according to  claim 1 , wherein the mutual interlocking relationship between the eccentric part ( 12 ) and the counterweight part ( 14 ) acts in a radial direction ( 76 ) in respect to the first rotational axis ( 28 ) of the eccentric part ( 12 ), at least during activation of the tool motor. 
     
     
         3 . Eccentric element ( 10 ) according to  claim 1 , wherein the mutual interlocking relationship between the eccentric part ( 12 ) and the counterweight part ( 14 ) acts in a circumferential direction ( 82 ) in respect to the first rotational axis ( 28 ) or the second rotational axis ( 34 ) of the eccentric part ( 12 ). 
     
     
         4 . Eccentric element ( 10 ) according to  claim 1 , wherein the mutual interlocking relationship between the eccentric part ( 12 ) and the counterweight part ( 14 ) acts in an axial direction ( 86 ) extending parallel to the first rotational axis ( 28 ) or the second rotational axis ( 34 ) of the eccentric part ( 12 ). 
     
     
         5 . Eccentric element ( 10 ) according to  claim 1 , wherein the first rotational axis ( 28 ) of the eccentric part ( 12 ) corresponds to a rotational axis of the tool shaft ( 16 ) once the eccentric part ( 12 ) is attached to the tool shaft ( 16 ), and/or the second rotational axis ( 34 ) of the eccentric part ( 12 ) corresponds to a rotational axis of the working element ( 30 ) once the working element ( 30 ) is attached to the eccentric part ( 12 ). 
     
     
         6 . Eccentric element ( 10 ) according to  claim 1 , wherein the eccentric element ( 10 ) comprises at least one fastening element ( 62 ), including a screw, configured for securing the counterweight part ( 14 ) in respect to the eccentric part ( 12 ) in their mutual interlocking relationship before, during and after activation of the tool motor. 
     
     
         7 . Eccentric element ( 10 ) according to  claim 1 , wherein
 the eccentric element ( 10 ) comprises at least one bearing ( 36 ) associated with the bottom surface ( 32 ) of the eccentric part ( 12 ) and configured to receive a rotational pin ( 38 ) in a manner freely rotatable about the second rotational axis ( 34 ) of the eccentric part ( 12 ), and   a distal end ( 40 ) of the rotational pin ( 38 ) is configured to be releasably attached to the working element ( 30 ).   
     
     
         8 . Eccentric element ( 10 ) according to  claim 7 , wherein
 the distal end ( 40 ) of the rotational pin ( 38 ) comprises a head portion ( 46 ) having a larger diameter than part ( 48 ) of the rotational pin ( 38 ), which is received in the at least one bearing ( 36 ), and having a non-rotational symmetric outer circumferential surface ( 50 ), the head portion ( 46 ) being configured to be received by a respective cavity ( 52 ) provided in the working element ( 30 ) and having an inner circumferential surface ( 56 ) corresponding to the non-rotational symmetric outer circumferential surface ( 50 ) of the head portion ( 46 ), and   the working element ( 30 ) is secured to the rotational pin ( 38 ) in an axial direction by means of a fastening element ( 58 ), including a screw.   
     
     
         9 . Eccentric element ( 10 ) according to  claim 7 , wherein a part of the counterweight part ( 14 ) facing the second rotational axis ( 34 ) of the eccentric part ( 12 ) after attachment to the eccentric part ( 12 ), holds the at least one bearing ( 36 ) in an axial direction in respect to the eccentric part ( 12 ). 
     
     
         10 . Eccentric element ( 10 ) according to  claim 1 , wherein the top surface ( 18 ) of the eccentric part ( 12 ) comprises a threaded hole ( 24 ), a longitudinal axis ( 26 ) of the threaded hole ( 24 ) corresponding to the first rotational axis ( 28 ) of the eccentric part ( 12 ), and the threaded hole ( 24 ) being configured to receive for releasable threaded attachment a threaded distal end ( 22 ) of the tool shaft ( 16 ) or of a component fixedly attached to the tool shaft ( 16 ) or forming an integral part therewith. 
     
     
         11 . Eccentric element ( 10 ) according to  claim 1 , wherein in a top view parallel to first and/or second rotational axes ( 28 ;  34 ) of the eccentric part ( 12 ), the eccentric part ( 12 ) has a circular form with the second rotational axis ( 34 ) forming a centre of the circular form. 
     
     
         12 . Eccentric element ( 10 ) according to  claim 1 , wherein
 in a bottom view parallel to first and/or second rotational axes ( 28 ;  34 ) of the eccentric part ( 12 ), the counterweight part ( 14 ) has a circular form or the form of a circular sector; and   a centre ( 90 ) of the circular form or of the circular sector is spaced apart from the second rotational axis ( 34 ).   
     
     
         13 . Eccentric element ( 10 ) according to  claim 12 , wherein the first rotational axis ( 28 ) extends through a straight line ( 92 ) interconnecting the centre ( 90 ) of the circular form or of the circular sector of the counterweight part ( 14 ) with the second rotational axis ( 34 ). 
     
     
         14 . Eccentric element ( 10 ) according to  claim 1 , wherein the eccentric part ( 12 ) is made of metal, including steel or aluminium, or of a plastic material having metal inserts. 
     
     
         15 . Eccentric element ( 10 ) according to  claim 1 , wherein the counterweight part ( 14 ) is made of metal, including steel. 
     
     
         16 . Eccentric element ( 10 ) according to  claim 2 , wherein the mutual interlocking relationship between the eccentric part ( 12 ) and the counterweight part ( 14 ) acts in a circumferential direction ( 82 ) in respect to the first rotational axis ( 28 ) or the second rotational axis ( 34 ) of the eccentric part ( 12 ). 
     
     
         17 . Eccentric element ( 10 ) according to  claim 16 , wherein the mutual interlocking relationship between the eccentric part ( 12 ) and the counterweight part ( 14 ) acts in an axial direction ( 86 ) extending parallel to the first rotational axis ( 28 ) or the second rotational axis ( 34 ) of the eccentric part ( 12 ). 
     
     
         18 . Eccentric element ( 10 ) according to  claim 2 , wherein the mutual interlocking relationship between the eccentric part ( 12 ) and the counterweight part ( 14 ) acts in an axial direction ( 86 ) extending parallel to the first rotational axis ( 28 ) or the second rotational axis ( 34 ) of the eccentric part ( 12 ). 
     
     
         19 . Eccentric element ( 10 ) according to  claim 2 , wherein the first rotational axis ( 28 ) of the eccentric part ( 12 ) corresponds to a rotational axis of the tool shaft ( 16 ) once the eccentric part ( 12 ) is attached to the tool shaft ( 16 ) and/or the second rotational axis ( 34 ) of the eccentric part ( 12 ) corresponds to a rotational axis of the working element ( 30 ), once the working element ( 30 ) is attached to the eccentric part ( 12 ). 
     
     
         20 . Eccentric element ( 10 ) according to  claim 2 , wherein the eccentric element ( 10 ) comprises at least one fastening element ( 62 ), including a screw, configured for holding the counterweight part ( 14 ) in respect to the eccentric part ( 12 ) in their mutual interlocking relationship before, during and after activation of the tool motor. 
     
     
         21 . Eccentric element ( 10 ) according to  claim 2 , wherein
 the eccentric element ( 10 ) comprises at least one bearing ( 36 ) associated with the bottom surface ( 32 ) of the eccentric part ( 12 ) and configured to receive a rotational pin ( 38 ) in a manner freely rotatable about the second rotational axis ( 34 ) of the eccentric part ( 12 ); and   a distal end ( 40 ) of the rotational pin ( 38 ) is configured to be releasably attached to the working element ( 30 ).   
     
     
         22 . Eccentric element ( 10 ) according to  claim 8 , wherein a part of the counterweight part ( 14 ) facing the second rotational axis ( 34 ) of the eccentric part ( 12 ) after attachment to the eccentric part ( 12 ), holds the at least one bearing ( 36 ) in an axial direction in respect to the eccentric part ( 12 ). 
     
     
         23 . Eccentric element ( 10 ) according to  claim 2 , wherein the mutual interlocking relationship acts and provides for a force relief in a direction ( 76 ) directed only radially outwards during rotation of the eccentric element ( 10 ) about the first rotational axis ( 28 ).