Filter unit having a constant rate purging cycle

Abstract

A filtering unit for use in a fluid pressure system having an inlet port for admitting fluid flowing under pressure through a filter and a desiccant bed to a distributing chamber. During the system's compression cycle, a portion of the fluid under pressure flows from the distributing chamber through metering orifices into a purge cylinder moving a piston therein to the bottom of the purge cylinder. During the system's purging cycle, fluid flowing under pressure is admitted to the bottom of the purge cylinder moving the piston towards the metering orifices causing the pressurized fluid therein to flow at a constant rate in a reverse direction through the filter and desiccant bed into a sump which is exhausted to the atmosphere through a drain valve for renewing the filter and desiccant bed. Also , a one-way valve is provided between the inlet port and the distributing chamber to permit the fluid flowing under pressure to bypass the filter and desiccant bed in the event they become clogged.

Dependencies are inferred from the claim text.