Regenerative air dryer

1. A modular valve cartridge for a regenerative air dryer including a housing having a dry air passage and a desiccant canister having a desiccant bed, the modular valve cartridge comprising:

a cylindrical body having an air passage extending axially there through between a first opening and second opening, a first end of the cylindrical body, including the first opening, to releasably couple to the housing to place the cartridge air passage in communication with the dry air passage via the first opening, and a second end of the cylindrical body, including the second opening, to releasably couple to the desiccant canister to place the cartridge air passage in communication with the desiccant bed via the second opening;

a check valve disposed within the cartridge air passage, the check value including a valve head and being moveable in a first direction to a closed position and in a second direction, opposite the first direction, to an open position, the check valve biased in the first direction to normally be in the closed position such that the valve head closes the second opening to close the cartridge air passage, and to be biased to the open position such that the valve head opens the second opening in response to receiving a pressurized air in the second direction via the second opening, the check valve including a regenerative orifice extending through the valve head to pass a pressurized air flow through the valve head from the first opening to the second opening when the check valve is in the closed position, the modular valve cartridge having a maximum air flow volume based on a size of the second opening of the cylindrical body and the size of the check valve;

and wherein there are threads on an external surface of the cylindrical body at the first and second ends.

2. The modular valve cartridge of claim 1 , the cylindrical body including an integral nut extending circumferentially about the external surface between the first and second ends.

3. The modular valve cartridge of claim 1 , the check valve including a spring to bias the valve in a normally closed position to close the cartridge air passage and prevent air flow through the cartridge air passage from the second end to the first end.

4. A regenerative air drying system comprising:

a housing including a dry air passage;

a desiccant canister including desiccant material forming a desiccant bed; and

a modular valve cartridge having a cartridge air passage, the modular valve cartridge to selectively couple to the desiccant canister and to selectively couple to the housing such that the desiccant bed is in communication with the dry air passage via the cartridge air passage, the modular valve cartridge including a check valve including a valve head biased in a normally closed position to prevent air flow from the dry air passage to the desiccant bed and to open in response to a pressurized dry air flow from the desiccant bed to enable the dry air flow from the desiccant bed to the dry air passage via the cartridge air passage, the valve head including regenerative orifice extending there through to pass a wash air flow from the cartridge air passage to the desiccant canister when in the closed position.

5. The regenerative air drying system of claim 4 , an external surface of the modular valve cartridge being threaded to selectively thread into respective openings in the desiccant canister and the housing.

6. The regenerative air drying system of claim 5 , the modular valve cartridge including an integral nut to limit an extent to which the modular valve cartridge can be threaded into the desiccant canister and into the housing.