Abstract A reciprocatory pneumatic tool has a positive displacement pump for introducing a constant volume of liquid into the tool side of the piston upon each return stroke, and a valve operated in timed sequence with the pump for exhausting liquid upon each return stroke. The air on the opposite side of the piston is confined and of constant quantity, so that when the tool encounters high resistance, the tool will not advance as far on the working stroke and liquid will tend to accumulate on the tool side of the piston and the air will be more greatly compressed to deliver a more powerful working stroke. Conversely, when the tool encounters less resistance, the tool advances farther on the working stroke and more liquid is pumped out than is pumped into the cylinder, so that the compressed air is expanded and delivers a less powerful stroke. The force of impact is thus automatically adjusted in accordance with the resistance encountered. In a modification, liquid can be pumped through the piston one way in the direction of the air, and an outlet port normally covered by the piston can be exposed when the piston moves too far in either direction.
In a pneumatic tool comprising a cylinder, and a piston in the cylinder that acts on a pneumatic tool to effect a working stroke under the influence of a gaseous medium which is on the side of the piston opposite the tool; the improvement comprising means for repeatedly supplying to the cylinder on the same side of the piston as the tool a constant volume of liquid between working strokes, and means to exhaust from the cylinder at least some of said liquid between periods of supply of said liquid thereby to permit the volume of said liquid in said cylinder to vary as the resistance met by said tool, a portion of said liquid being disposed on said opposite side of said piston, said gaseous medium being confined in an accumulator in which is also disposed a portion of said liquid, said piston having a duct therethrough communicating between opposite sides of said piston, said cylinder having an outlet port for said liquid, the range of possible movement of said piston being such as to permit exposure of said outlet port by said piston on either side of said piston.
Claim 2
Dependent Claim
191 words
In a pneumatic tool comprising a cylinder, and a piston in the cylinder that acts on a pneumatic tool to effect a working stroke under the influence of a gaseous medium which is on the side of the piston opposite the tool; the improvement comprising means for repeatedly supplying to the cylinder on the same side of the piston as the tool a constant volume of liquid between working strokes, and means to exhaust from the cylinder at least some of said liquid between periods of supply of said liquid thereby to permit the volume of said liquid in said cylinder to vary as the resistance met by said tool, a portion of said liquid being disposed on said opposite side of said piston, said gaseous medium being confined in an accumulator in which is also disposed a portion of said liquid, said piston having a duct therethrough communicating between opposite sides of said piston, said cylinder having an outlet port for said liquid, the range of possible movement of said piston being such as to permit exposure of said outlet port by said piston on either side of said piston.
Claim 3
Dependent Claim
32 words
Apparatus as claimed in claim 1, and a one-way check valve in said duct to permit flow of liquid toward said accumulator but to prevent flow of liquid away from said accumulator.
Claim 4
Dependent Claim
12 words
Apparatus as claimed in claim 1, and throttling means in said duct.