US 5,873,418 A · Percussive tool having a reduced impact at the start of percussive operation

Abstract

A percussive tool generates a reduced impact at the start of percussive operation following idling operation. The percussive tool has a cylinder containing a piston, an air chamber in front of the piston, and a striker disposed in front of the air chamber. A slide sleeve and a rimmed ring at the rear end thereof are fitted around the cylinder. The cylinder has formed therein an exhaust port and auxiliary ports in front of the exhaust port for placing the air chamber in communication with the atmosphere. When the slide sleeve is retracted, the exhaust port is closed by the rimmed ring. During percussive operation of the percussive tool, the auxiliary ports are always closed by the reciprocating striker and therefore not open to the air chamber. During idling operation, the striker takes an advanced position and opens the auxiliary ports, thereby placing the air chamber in communication with the atmosphere. The distance between the rear end of the striker and the auxiliary ports is set slightly shorter than the distance between the rear end of the ring and the exhaust port in normal operation, so that the auxiliary ports are opened prior to the exhaust port.

Claims10

Dependent claims

A percussive tool comprising:

a cylinder;
a piston contained and reciprocable in said cylinder;
an air chamber formed adjacent to said piston in said cylinder for creating an air spring therein;
at least one exhaust port formed in the part of said cylinder where said air chamber is located;
a striker element contained in said cylinder and capable of being interlocked with said piston via said air spring created in said air chamber to transmit a percussive motion performed by said piston to a tool bit mounted at a front end of the percussive tool;
an axially displaceable slide sleeve mounted around said cylinder and urged forward, said slide sleeve being retracted to close said at least one exhaust port formed in said cylinder when said percussive motion is transmitted and being advanced to open said at least one exhaust port during idling operation;
and
ventilation control means formed in said cylinder for restraining the effect of said air spring in said air chamber by placing said air chamber in communication with the atmosphere at least for a predetermined time period after said at least one exhaust port is closed by said slide sleeve during a switchover from idling operation to normal percussive operation.

5 more elements

Dependencies are inferred from the claim text.

Percussive tool having a reduced impact at the start of percussive operation

Life of this patent

Percussive tool having a reduced impact at the start of percussive operation

Life of this patent

Abstract

Claims10