Patent CA-1145961-A (CA)
Inventor: CHELMINSKI STEPHEN V
IPC: B21J7/24
Filed: 1980-07-22
Granted: 1983-05-10
Abstract: 735.066 GKP     S P E C I F I C A T I O N      QUIET BOUNCER PILE DRIVER METHOD AND APPARATUS WITH ANNULAR AIR STORAGE CHAMBER ENCIRCLING AND TRAVELLING            WITH BOUNCING PISTON WEIGHT               Inventor :  Stephen V. Chelminski ABSTRACT OF THE DISCLOSURE              A massive piston weight, which might be called a "ram" except that it does not strike anything during pile driving operation, reciprocates with a bouncing action up and down within a cylinder.  The intermediate portion of this piston weight has a narrowed waist spaced inwardly from the cylinder wall to provide an annular pressurized gas storage chamber which encircles and travels with the piston weight.          Pressurized gas is continuously fed through the cylinder wall into this  movable annular chamber to be accumulated therein.          As the piston weight falls toward a bottom assembly at the lower end of the cylinder, the accumulated pressurized gas in this travelling annular chamber is suddenly allowed to bypass the lower portion of the piston weight, thereby suddenly being injected into a bounce chamber between the piston weight and the bottom assembly.   When this surge of pressurized gas pass-es through the bypass into the bounce chamber it forces an ex-haust valve closed, so that the bounce chamber can be charged with the injected compressed gas.  The bypass includes two vertically spaced sets of gas feed ports in communication with both the cylinder and an outer shroud surrounding the cylinder wall.  As the piston weight continues falling closer to the bottom assembly, the injected pressurized gas is suddenly trapped within the bounce chamber and is further compressed as a cushion with great pressure multiplication between the falling piston weight and the bottom assembly to drive the bottom assembly downwardly for driving a pile.  The rapid in-crease in pressure of the trapped gas in the bounce chamber bounces the massive piston weight upwardly in a powerful bouncing action producing a powerful driving thrust on the pile being driven.  As the piston weight is ascending addi-tional pressurized gas bypasses from the annular storage chamber into the cylinder beneath the piston weight, and ex-pansion of this additional gas aids in propelling the ascend-ing piston weight up to a relatively high position within the cylinder.  The ascending piston weight allows the gas in the cylinder to expand until the pressure within the cylinder beneath the piston has dropped approximately to atmospheric pressure, thereby allowing the exhaust valve automatically to open.  At the time when the exhaust valve opens the piston weight is near the top of its stroke, and it begins falling again while the gas escapes through the open exhaust valve from the cylinder below the descending piston.  Thus, the piston weight is now again falling toward the bottom assembly and the cycle repeats.  The massive piston weight is quiet in operation for it is bouncing upon compressed gas.  A muffler associated with the exhaust valve quiets the exhaust gas flow During start-up of the pile driver, the exhaust valve, which is in the form of a large ring encircling the whole cylinder, is biased toward its open position but is held closed by pressurized gas being fed into the bounce chamber for raising the piston weight.  This pressurized gas is slowly fed into the bounce chamber through a pathway including special grooves in the lower surface of at least one piston ring, and the massive piston weight is thereby initially slowly lifted up from the bottom assembly.  As soon as the piston weight clears the lower set of gas feed ports, pressurized gas is injected directly into the cylinder beneath the piston weight for throwing it upwardly in the cylinder to start the cycle of operation.  During operation, the specially grooved piston ring(s) do not leak, because it is the upper surface of each ring which provides the sealing action during normal operation.  These grooves also help to expand the rings as gas pressure builds up in the bounce chamber, thereby augmenting the piston ring sealing action.