Sound absorber for an intermittently discharged gaseous working medium

摘要

A sound absorber for intermittent exhaust gas, particularly for use in connection with a compressed air operated motor employed, for example, in a hand grinder. The sound absorber is arranged predominantly in the housing of the motor and includes an exhaust air discharging channel having an alternately varying cross-section to define a succession of continuously alternating narrow and wide passages for changing continuously the direction of flow of the exhaust air about an angle that is always lower than 90 DEG with respect to the axis of the discharge channel so that the ratio of successive minimum and maximum cross-sections of the channel is at most 4:1. The discharge channel is terminated with a nozzle plate defining a plurality of outlet nozzles the central axes of which converge in the direction of flow. The discharge channel further includes at least one dead air space which in the case of a hand grinder is preferably formed by the interior of a hollow handle of the grinder and a portion of the discharge channel is divided by an air guiding partition into two partial conduits of different lengths and each communicating with one group of outlet nozzles.