Portable percussive machine
First Claim
1. A percussive machine comprising a housing having a cylinder including a bottom end housed therein, a drive piston reciprocally movable within said cylinder for repeatedly driving a hammer piston towards said bottom end via a gas cushion in a working chamber defined in said cylinder between said drive piston and said hammer piston, said hammer piston impacting against a neck of a tool carried by said housing at said bottom end, said hammer piston being displaced towards said bottom end of said cylinder past ports defined in a wall of said cylinder through which said gas cushion in said working chamber is relieved to inactivate said hammer piston when said tool is displaced away from said bottom end to a position out of the reach of said hammer piston, said machine further including a braking chamber defined in said cylinder between said ports and said bottom end of said cylinder for pneumatically braking said displacement of said hammer piston, and means in said housing for resiliently supporting said bottom end of said cylinder to allow displacement of said bottom end relative to said cylinder in response to pneumatic pressure generated by said hammer piston in said braking chamber during said displacement of said hammer piston into said braking chamber.
1 Assignment
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Accused Products
Abstract
A percussive machine comprises a housing (10) with a cylinder (11) therein, in which a reciprocating drive piston (40) via a gas cushion in a working chamber (44) repeatedly drives a hammer piston (15) to impact on the neck (17) of a tool (20) carried by the housing (10). At empty blows with the neck (17) out of reach, the hammer piston (15) is thrown forwardly and caught pneumatically in a braking chamber (47) at the bottom end (12) of the cylinder (11). The braking is combined with an elastic yielding of the bottom end (12) against the action of a recoil spring (23) in the housing (10). The pressure in the braking chamber (47) during such yielding is controlled by throttling apertures (48) in the cylinder (11) uncovered by the bottom end (12). The hammer piston (15) is thus checked to halt pneumatically by throttling avoiding a collision with the bottom end (12) and takes an inactive position below ports (46) in the cylinder wall through which the working chamber (44) is relieved and ventilated. The bottom end (12) is returned upon yielding by the recoil spring (23) and closes the throttling apertures (48) by check valve action.
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Citations
8 Claims
- 1. A percussive machine comprising a housing having a cylinder including a bottom end housed therein, a drive piston reciprocally movable within said cylinder for repeatedly driving a hammer piston towards said bottom end via a gas cushion in a working chamber defined in said cylinder between said drive piston and said hammer piston, said hammer piston impacting against a neck of a tool carried by said housing at said bottom end, said hammer piston being displaced towards said bottom end of said cylinder past ports defined in a wall of said cylinder through which said gas cushion in said working chamber is relieved to inactivate said hammer piston when said tool is displaced away from said bottom end to a position out of the reach of said hammer piston, said machine further including a braking chamber defined in said cylinder between said ports and said bottom end of said cylinder for pneumatically braking said displacement of said hammer piston, and means in said housing for resiliently supporting said bottom end of said cylinder to allow displacement of said bottom end relative to said cylinder in response to pneumatic pressure generated by said hammer piston in said braking chamber during said displacement of said hammer piston into said braking chamber.
Specification