Percussive tool

A percussive tool comprising a percussion mechanism having:

• a hollow housing the interior of which is isolated from the outside, said housing having a working end;
• a piston hammer arranged in the interior of said housing for reciprocation therein and separating the interior of said housing into two closed chambers of variable volume, said chambers including a first chamber and a second chamber, said first chamber communicating only with said second chamber, and said second chamber communicating with said first chamber and with a source of pressurized gaseous fluid;
• a restrictor passage continuously freely intercommunicating said first and second chambers of said housing during the entire operation of the percussive tool;
• and
• a pressure pulser having:
• a housing;
• a source of gaseous fluid;
• a fluid displacer arranged inside said housing of said pressure pulser and defining with the walls of said housing a working chamber;
• communicating means for communicating said working chamber with said source of gaseous fluid, said communicating means including an opening provided in the side surface of the housing of the pressure pulser to communicate said working chamber with the source of gaseous fluid and also to be closed by the side surface of the fluid displacer depending on the position of the fluid displacer relative to the housing of the pressure pulser;
• means for constantly communicating said working chamber with said second chamber of said percussion mechanism while said first chamber of said percussion mechanism remains closed except for the continuous free intercommunication between said first chamber and said second chamber provided by said restrictor passage;
• and
• driving means for driving said fluid displacer inside said housing of said pressure pulser for periodically varying the volume of said working chamber to transmit to said second chamber of said percussion mechanism a pulsed pressure under action of which reciprocations of said piston hammer are effected to deliver impacts to said working end of said hollow housing.