Filter device for compressed air

1 . A filter device for compressed air, comprising:

a first filter assembly having a first air inlet and a first air outlet, wherein the first air inlet is configured to receive compressed air to be filtered;

a second filter assembly having a second air inlet and a second air outlet, wherein the second air inlet is in fluid communication with the first air outlet;

a third filter assembly having a third air inlet and a third air outlet, wherein the third air inlet is in fluid communication with the second air outlet, and the third air outlet is configured to discharge filtered compressed air for use;

an air pressure regulating assembly connected to an upper end of the second filter assembly, the air pressure regulating assembly having an air inlet passage in fluid communication with the second air inlet, wherein the air pressure regulating assembly is configured to regulate pressure of air entering the second filter assembly.

2 . The filter device according to claim 1 , wherein the air pressure regulating assembly comprises a base, a first elastic component, a valve needle, an active valve, a second elastic component, a moving part, and an adjustment knob;

the base is connected to the upper end of the second filter assembly, and the base is provided with the air inlet passage and a valve chamber;

the first elastic member comprises two ends respectively abutting against a bottom of the valve needle and a bottom wall of the valve chamber;

the valve needle is movably abutted against the active valve to open or close a vent hole in the active valve;

a lower end of the second elastic component is abutted against an upper portion of the active valve, and an upper end of the second elastic component is abutted against the moving part;

the adjustment knob is rotatably connected to the base and configured to drive the moving part upward and downward;

a side wall of the base is further provided with an exhaust hole in fluid communication with the valve chamber.

3 . The filter device according to claim 2 , wherein the active valve is provided with a first sealing component, wherein the vent hole extends through the active valve and the first sealing component;

an upper end of the valve needle abuts against the first sealing component and covers the vent hole;

an outer surface of the active valve comprises a first sealing ring sealingly engaged with an inner wall of the valve chamber.

4 . The filter device according to claim 2 , wherein the adjustment knob comprises a threaded rod portion extending through a top wall of the valve chamber into the valve chamber;

wherein the moving part is threadedly engaged with the threaded rod portion and configured to slide upward and downward within the valve chamber.

5 . The filter device according to claim 2 , wherein the second filter assembly comprises an elastic driving piece, a push rod, a push rod seat, and a third elastic component;

wherein the elastic driving piece is positioned between the base and the second filter assembly, wherein a pressure chamber is formed between the elastic driving piece and the base;

the base comprises an air guiding passage communicating the valve chamber with the pressure chamber;

an exhaust chamber communicating with the second air outlet is formed between the elastic driving piece and an upper surface of the second filter assembly;

an upper portion of the second filter assembly is provided with a push rod chamber; the push rod chamber is in communication with the exhaust chamber through an air guide hole;

a lower end of the third elastic component is abutted against a lower wall of the push rod chamber, an upper end of the third elastic component is abutted against the push rod seat, thereby biasing the push rod seat toward covering the air guide hole;

and an upper end of the push rod is abutted against a lower surface of the elastic driving piece.

6 . The filter device according to claim 5 , wherein the second filter assembly is provided with a limiting groove;

wherein the push rod seat comprises an insertion portion and an abutting portion, and a second sealing ring is disposed around an outer periphery of the insertion portion;

the insertion portion is movably inserted into the limiting groove;

an upper surface of the abutting portion is provided with a third sealing ring that surrounds and seals the air guide hole when the push rod seat is in a position covering the air guide hole.

7 . The filter device according to claim 1 , wherein the first filter assembly comprises a first mounting seat, a first filtering component, a first housing, and an automatic drain device;

wherein the first housing is connected to the first mounting seat, the first housing and the first mounting seat together enclose a first filtering space;

the first filtering component is connected to the first mounting seat and is accommodated within the first filtering space;

wherein the automatic drain device is disposed in the first filtering space, and the automatic drain device is configured to open a drain passage when a liquid level of accumulated liquid is higher than a preset level, thereby discharging the accumulated liquid.

8 . The filter device according to claim 7 , wherein the automatic drain device comprises a limiting housing, a floating part, a second sealing component, a drain seat, and a fourth elastic component;

wherein a lower portion of the drain seat is provided with a drainage hole communicating with the drain passage;

the second sealing component is disposed in the drain seat;

wherein a lower end of the fourth elastic component is abutted against an upper surface of the second sealing component, an upper end of the fourth elastic component is abutted against an inner wall of the drain seat, thereby biasing the second sealing component toward sealing the drainage hole;

the floating part is connected to the second sealing component through a connecting rod; and

the floating part is configured to, under an action of a buoyancy force exerted by the accumulated liquid, drive the second sealing component away from the drainage hole;

and the limiting housing is disposed to cover the floating part.

9 . The filter device according to claim 8 , wherein the drain seat is provided with a limiting boss, the floating part is provided with a limiting channel, the limiting boss is inserted into the limiting channel, and the connecting rod extends through the limiting boss.

10 . The filter device according to claim 5 , wherein the second filter assembly comprises a second mounting seat, a second filtering component, and a second housing;

wherein the second housing is connected to the second mounting seat, and the second housing and the second mounting seat together enclose a second filtering space; and

the second filtering component is connected to the second mounting seat and is accommodated within the second filtering space.

11 . The filter device according to claim 1 , wherein the third filter assembly comprises a third mounting seat, a third filtering component, and a third housing;

wherein the third housing is connected to the third mounting seat, the third housing and the third mounting seat together enclosing a third filtering space; and

the third filtering component is connected to the third mounting seat and accommodated within the third filtering space.

12 . The filter device according to claim 7 , wherein the first filter assembly further comprises a first protective cover and a first connecting rod;

wherein an upper end of the first connecting rod is threadedly connected to the first mounting seat, a lower end of the first connecting rod is threadedly connected to a bottom of the first protective cover and a bottom of the first filtering component;

an upper portion of the first filtering component is abutted against the first mounting seat;

the bottom of the first protective cover is further provided with a plurality of through holes.

13 . The filter device according to claim 7 , wherein the first filtering component is a frustoconical porous brass filter having a wider upper portion and a narrower lower portion.

14 . The filter device according to claim 10 , wherein the second filter assembly further comprises a first end cap, a second connecting rod, and a second end cap;

wherein the first end cap and the second end cap are respectively sleeved over two ends of the second filtering component;

an upper end of the second connecting rod is threadedly connected to the second mounting seat, and a lower end of the second connecting rod passes through the first end cap and the second filtering component, and the second connecting rod is fixedly connected to the second end cap.

15 . The filter device according to claim 14 , wherein the second filtering component is a cylindrical coalescing filter formed by multiple layers of filter media sequentially wound and enclosed around each other.

16 . The filter device according to claim 11 , wherein the third filter assembly further comprises a third connecting rod;

wherein an upper end of the third connecting rod passes upwardly through the third filtering component and is threadedly connected to the third mounting seat; and

a lower end of the third connecting rod abuts against a lower portion of the third filtering component.

17 . The filter device according to claim 16 , wherein the third filtering component is an activated carbon filter.

18 . The filter device according to claim 14 , wherein the second mounting seat is provided with an annular airflow chamber, an airflow inlet channel, and an airflow outlet channel;

wherein the annular airflow chamber in communication with the second air inlet, the airflow inlet channel in communication with the annular airflow chamber and a central cavity of the second filtering component, and the airflow outlet channel in communication with the second filtering space and the push rod chamber.

19 . The filter device according to claim 10 , wherein the second filter assembly is further provided with a semi-automatic drain assembly configured to allow accumulated liquid to flow out upon manual pressing by a user;

wherein the semi-automatic drain assembly comprises a movable plug and a fourth sealing ring, a bottom of the second housing is provided with a drain channel and a counterbore communicating with the drain channel;

the fourth sealing ring is disposed in the counterbore;

the movable plug comprises a main body portion and a head portion, the main body portion is movably inserted in the drain channel, and the head portion is movably inserted in the counterbore and is configured for selectively abutting against or separating from the fourth sealing ring.

20 . The filter device according to claim 19 , wherein the semi-automatic drain assembly further comprises a fifth elastic component;

wherein an inner wall of the drain channel is provided with a mounting platform;

a lower end of the fifth elastic component is abutted against the mounting platform; an upper end of the fifth elastic component is abutted against the head portion; and

a portion of an outer surface of the main body portion that protrudes out of the drain channel is further provided with a limiting portion, the limiting portion is configured to limit a distance by which the main body portion enters the drain channel.