GB1325498A - Pressurized gas driven motors - Google Patents

Abstract

1325498 Impelling-tools ATLAS COPCO AB 4 Nov 1970 [7 Nov 1969] 52397/70 Heading B4C [Also in Division F1] A tool comprises a cylinder housing 4 and a hollow drive piston 5 reciprocably guided in the housing, the chamber 6 enclosed by the piston being arranged to be fed with gas under pressure from a source thereof, and the piston and housing having openings 13-17 and the housing having distributing channels 18, 19 for distributing pressure gas from the chamber 6 to piston work and return stroke chambers 12a, 12b and from these chambers to atmosphere in such a way that the piston is driven backwards and forwards in the housing. The openings 14, 20 are so located in the housing that when the piston approaches its rear end position a closed chamber 12a is formed in which a cushion of gas is trapped which causes the piston to rebound. The piston has a driving portion 23 which drives, e.g., a hammer piston 22, via a cushion of gas 25 which also causes the piston to rebound at its forward end position. In the embodiment shown, the hammer piston 22 is arranged to drive a drill steel. An auxiliary piston 24 having a flange 27 engages a flange 28 on the piston 22 during the return stroke thereof to position this piston ready for the next stroke. Air under pressure is admitted to the chamber 25 via an opening 26 when the piston 5 is retracted, and this air passing through clearances maintains the piston 24 in its lowest position and provides cushioning in a chamber 31 for the piston 22. In a second embodiment, of reduced length, the drive piston is annular and the hammer piston passes through the centre thereof. The auxiliary piston is above the drive piston and engages the rear end of the hammer piston on its return stroke. The cushioning chamber for the drive piston is provided by an internal flange on the drive piston and an external flange on the hammer piston. In a third embodiment, Fig. 3 (not shown), intended for "down the hole" drilling, the drive-piston includes a plurality of pistons working in several respective coaxial cylinder chambers. The drive piston includes a second chamber which receives exhaust gases from the motor and directs them via an extension of the drive piston through the hammer piston and a drill tool, for flushing. In any embodiment the tool can be fitted with a drill steel chuck and drill steel rotation mechanism.