Plural-stage air filter assembly

Claim 2

AN ASSEMBLY FOR FILTERING COMPRESSED AIR, COMPRISING A HOUSING HAVING AN INLET PORT CONNECTABLE TO AN OUTLET OF A COMPRESSOR FOR ADMITTING COMPRESSED AIR THEREFROM INTO SAID HOUSING AND AN OUTLET PORT, SAID HOUSING CONTAINING MEANS FOR FILTERING COMPRESSED AIR PASSING THERETHROUGH BETWEEN SAID INLET AND OUTLET PORTS AND A SUMP HAVING A DRAIN PORT FOR COLLECTING AND DISCHARGING CONTAMINANTS, A DRAIN VALVE OPENING INDEPENDENTLY OF AIR PRESSURE WITHIN SAID HOUSING IN RESPONSE TO AND SUBSTANTIALLY THROUGHOUT UNLOADING OF SAID COMPRESSOR FOR DRAINING CONTAMINANTS FROM SAID SUMP THROUGH SAID DRAIN PORT, AND VALVE MEANS IN SAID INLET PORT FOR CONTROLLING FLOW OF COMPRESSED AIR THERETHROUGH INTO SAID HOUSING, SAID VALVE MEANS BEING OPEN DURING A PUMPING CYCLE OF SAID COMPRESSOR AND CLOSING AT A PREDETERMINED LOW PRESSURE DURING AN UNLOADING CYCLE THEREOF FOR THEN MAINTAINING SAID LOW PRESSURE IN SAID COMPRESSOR BY PREVENTING COMPLETE UNLOADING THEREOF THROUGH SAID DRAIN PORT.

Claim 3

A plural-stage assembly for filtering compressed air, comprising a housing divided vertically into detachably connected upper and lower parts, said housing having on an upper portion of said upper part an inlet port connected directly to a compressor and an outlet port, a vertical bore in said upper portion of said upper part and having a downward extension of larger diameter in a lower portion of said part, a helical air passage in said upper portion about said bore and opening upwardly onto said inlet port and downwardly onto an interior of said lower portion outwardly of said bore extension therein, said helical passage directing compressed air from said inlet port to flow cyclonically downwardly therethrough for centrifugally filtering contaminants from said air and cooling said air by concentrating heat therefrom on said upper portion and discharging said air and contaminants into said interior of said lower portion outwardly of said bore extension, baffle means in said lower portion between a side wall thereof and said bore extension for arresting the cyclonic flow of said air to prevent forming of a boundary layer of dead air along said side wall while passing said air and contaminants, external finning on said upper and lower portions of said upper part for transferring heat to ambient air, a sump in said lower part opening upwardly onto said interior of said lower portion and having a drain port in a bottom thereof, external and internal finning on said lower part, a porous filter unit having a hood slidably received in said baffle means in said lower portion and seated in said downward bore extension and a filter element contained in said hood for filtering air passing therethrough from said sump, tube means fixed to said hood and slidably received in and extending upwardly through said bore for passing to said outlet port air received from said filter unit, and drain valve means suspended from said housing below said drain port for periodically draining therethrough contaminants collected in said sump.

Claim 4

A plural-stage assembly for filtering compressed air, comprising a housing divided vertically into detachably connected upper and lower parts, said housing having on an upper portion of said upper part an inlet port connected directly to a compressor and an outlet port, a vertical bore in said upper portion of said upper part and having a downward extension of larger diameter in a lower portion of said part, a helical air passage in said upper portion about said bore and opening upwardly onto said inlet port and downwardly onto an interior of said lower portion outwardly of said bore extension therein, said helical passage directing compressed air from said inlet port to flow cyclonically downwardly therethrough for centrifugally filtering contaminants from said air and cooling said air by concentrating heat therefrom on said upper portion and discharging said air and contaminants into said interior of said lower portion outwardly of said bore extension, baffle means in said lower portion between a side wall thereof and said bore extension for arresting the cyclonic flow of said air to prevent forming of a boundary layer of dead air along said side wall while passing said air and contaminants, external finning on said upper and lower portions of said upper part for transferring heat to ambient air, a sump in said lower part opening upwardly onto said interior of said lower portion and having a drain port in a bottom thereof, external and internal finning on said lower part, a porous filter unit having a hood slidably received in said baffle means in said lower portion and seated in said downward bore extension and a filter element contained in said hood for filtering air passing therethrough from said sump, tube means fixed to said hood and slidably received in and extending upwardly through said bore for passing to said outlet port air received from said filter unit, and drain valve means suspended from said housing below said drain port for periodically draining therethrough contaminants collected in said sump.

Claim 5

A plural-stage assembly according to claim 1, wherein the baffle means are vertically spaced rows of circumferentially spaced baffles staggered relative to baffles of any adjoining row and instanding radially from the side wall of the lower portion to and laterally bounding the downward bore extension, and the external finning on said upper and lower portions are respectively a helical fin following the perimeter of the helical passage and a plurality of vertically spaced rows of annular radial fins.

Claim 6

A plural-stage assembly according to claim 2, wherein the external and internal finning of the lower part are circumferentially spaced vertical fins respectively radially outstanding and instanding from a side of said part and said inner vertical fins support the porous filter unit.

Claim 7

A plural-stage assembly according to claim 1, wherein the filter unit is one of a pair of selectively interchangeably coarse and fine filter units each removable with the tube fixed thereto from the housing on detachment of the lower part from the upper part.

Claim 8

A plural-stage assembly according to claim 1, wherein the drain valve means is a double-seated drain valve having a pair of opposed alternately seatable valve elements on a differential piston and opening at short intervals during advance and return movements of said piston for draining contaminants through the drain port without substantially affecting air pressure in advance of and beyond the assembly.

Claim 9

A plural-stage assembly according to claim 1, wherein the drain valve means is a single-seated drain valve having a single valve element on a differential piston and opening in response to unloading of the compressor, and including inlet and outlet check valve means respectively communicating with the inlet and outlet ports, said check valve means being open during a filtering cycle of the assembly, and said inlet check valve means closing at a pressure predetermined to prevent complete unloading of the compressor.

Claim 10

A plural-stage assembly according to claim 4, wherein the drain valve means is a double-seated drain valve having a pair of opposed alternately seatable valve elements on a differential piston and opening at short intervals during advance and return movements of the piston for draining contaminants through the drain port without substantially affecting air pressure in advance of and beyond the assembly.

Claim 11

A plural-stage assembly according to claim 4, wherein the drain valve means is a single-seated drain valve having a single valve element on a differential piston and opening in response to unloading of the compressor, and including inlet and outlet check valve means respectively communicating with the inlet and outlet ports, said check valve means being open during a filtering cycle of the assembly, and said inlet check valve means closing at a pressure predetermined to prevent complete unloading of the compressor.

Claim 12

A plural-stage assembly according to claim 4, wherein each of the filter units includes a bypass passage inside the filter element thereof, and a check valve normally closing said passage and openable under a predetermined pressure differential between the sump and said passage for enabling the filter element to be bypassed in the case of plugging thereof.

Claim 13

An air filter assembly according to claim 10, including a check valve in the outlet port open while the compressor is pumping and closing on unloaDing thereof for preventing loss of pressure beyond the outlet port.