Patent ID: 9221162
Filing Date: 2015-12-29
Classification: B25C

Abstract:
1. A pneumatic driving machine comprising: a housing; a cylinder provided in said housing; a piston reciprocating between a first position and a second position within said cylinder and dividing the interior of said cylinder into an above-the-piston chamber and a below-the-piston chamber; an accumulator accumulating compressed air for moving said piston from said first position to said second position; a main valve sending said compressed air accumulated in said accumulator to said above-the-piston chamber to move said piston from said first position to said second position upon operation of a trigger; a return air chamber communicating with said above-the-piston chamber and said below-the-piston chamber while said piston is positioned at said second position, and accumulating compressed air supplied from said above-the-piston chamber when said piston moves from said first position to said second position; a push lever connected to said housing via a first resilient member and biased by the first resilient member to abut on a workpiece; a driver blade fixed to said piston and hitting and driving a fastener into said workpiece; and a driving force control mechanism controlling the driving force of said driver blade for hitting said fastener based on a moving distance of said housing relative to said push lever as a result of receiving a reaction force from said workpiece upon driving said fastener, wherein: at least said cylinder is disposed in a first air path between said accumulator and said return air chamber in said housing, at least said driving force control mechanism is disposed in a second air path between said above-the-piston chamber and said return air chamber in said housing, and said driving force control mechanism increases a resistance to said piston, by said push lever maintaining the second air path in an open state, as the moving distance of said housing relative to said push lever as a result of receiving said reaction force from said workpiece upon driving said fastener is smaller.