| 摘要 |
<p>A self-cycling reciprocating piston motor has the piston biased in return stroke direction and driven in power stroke by air pressure introduced between the head of the piston and a closure across the end of the working chamber cylinder. A valve which closes an exhaust port leading from the working chamber, is opened at the end of the power stroke by working chamber air pressure and the air pressure is evacuated from the working chamber. The valve is returned to closing relation to the port by the returning piston, thereby resetting the motor for another cycle of operation. Working chamber air pressure leads through an air passage from an escape port opening through the cylinder and adapted to be exposed to the working chamber at substantially the end of the power stroke of the piston. The piston has a peripheral groove within which is mounted a pair of O-rings for maintaining a sealed engagement with the cylinder, the O-rings occupying less than the full width of the groove, so that as the piston reaches the escape port, the O-ring nearest the piston rod and of the piston passes the escape port while the o-ring nearest the head end of the piston maintains a sealed relationship about the piston and escape of air pressure is prevented until the first O-ring has passed the escape port, whereafter the second O-ring follows past the escape port and pressure air can escape from the head end of the piston through the groove and out through the escape port, whereby stalling of the piston is prevented.</p> |
