Rotary air connection with central valve for tire inflation system

1. An automatic tire inflation system comprising:

a rotary fluid connection in substantially continuously-pressurized sealed fluid communication with a fluid pressure source and continuously receiving from the fluid pressure source a pressurized fluid at a substantially constant predetermined fluid pressure for inflating a pneumatic tire, the rotary fluid connection having an axis of rotation and comprising:

a stationary portion having a first channel formed therein on the axis of rotation;

a rotatable portion rotatably coupled to the stationary portion and in continuous sealing contact with the stationary portion at a sealing interface, the rotatable portion having a second channel formed therein on the axis of rotation and in substantially sealed fluid communication with the first channel, the first channel and second channel together forming a central channel on the axis of rotation through which the pressurized fluid for inflating a pneumatic tire may flow; and

a normally-closed check valve disposed in the central channel along the axis of rotation so as to allow the pressurized fluid to flow from the fluid pressure source in one direction through the central channel toward a pneumatic tire but not in the opposite direction toward the fluid pressure source, the normally-closed check valve being directly pneumatically actuatable by the pressurized fluid at the substantially constant predetermined fluid pressure from the pressure source while the rotary fluid connection is in substantially continuously-pressurized sealed fluid communication with the fluid pressure source, the normally-closed check valve being configured to open when fluid pressure in the pneumatic tire is lower than the substantially constant predetermined fluid pressure and close when the fluid pressure in the pneumatic tire substantially equals the substantially constant predetermined fluid pressure; and

a pneumatic tire in sealed fluid communication with the rotary fluid connection such that the pressurized fluid for inflating a pneumatic tire may flow to the pneumatic tire from the rotary fluid connection.

2. The rotary fluid connection of claim 1 , wherein the normally-closed check valve is disposed in one of the first channel of the stationary portion and the second channel of the rotatable portion.

3. The rotary fluid connection of claim 1 further comprising a rotatable tube, wherein the stationary portion comprises a stator having the first channel therein, and the rotatable portion comprises a tee body having the second channel therein, the stator and tee body in fluid communication through the rotatable tube, and the first channel of the stator, the rotatable tube and the second channel of the tee body together forming the central channel.

4. The rotary fluid connection of claim 3 , wherein the normally-closed check valve is disposed in one of the first channel of the stator, the rotatable tube and the second channel of the tee body.

5. The rotary fluid connection of claim 1 , wherein the stationary portion comprises a shaft having the first channel therein, and the rotatable portion comprises a hubcap having the second channel therein, and the first channel of the shaft and the second channel of the hubcap together forming the central channel.

6. The rotary fluid connection of claim 5 , wherein the normally-closed check valve is disposed in one of the first channel of the shaft and the second channel of the hubcap.

7. The rotary fluid connection of claim 1 , wherein the stationary portion comprises a shaft having the first channel therein, and the rotatable portion comprises a housing having a graphite element disposed therein, the housing and the graphite element having the second channel therein and, the graphite element being urged against the shaft to form a face seal, and the first channel of the shaft and the second channel of the housing and the graphite element together forming the central channel.

8. The rotary fluid connection of claim 7 , wherein the normally-closed check valve is disposed in one of the first channel of the shaft and the second channel of the housing and graphite element.

9. The rotary fluid connection of claim 1 , wherein the stationary portion comprises a stator having the first channel therein and the rotatable portion comprises a rotatable tube having a tee body together forming the second channel therein, and the first channel of the stator and the second channel of the rotatable tube and tee body together forming the central channel.

10. The rotary fluid connection of claim 9 , wherein the normally-closed check valve is disposed in one of the first channel of the stator and the second channel of the rotatable tube and tee body.

11. The rotary fluid connection of claim 1 , wherein the normally-closed check valve comprises an automobile tire valve.

12. The rotary system of claim 1 , further comprising a pressure regulator in substantially continuously-pressurized sealed fluid communication with the air pressure source and the rotary air connection.

13. A rotary fluid connection capable of substantially continuously-pressurized sealed fluid communication with a fluid pressure source and capable of continuously receiving from the fluid pressure source a pressurized fluid at a substantially constant predetermined fluid pressure for inflating a pneumatic tire, rotary fluid connection having an axis of rotation and comprising:

a stationary portion having a first channel formed therein on the axis of rotation;

a rotatable portion rotatably coupled to the stationary portion and in continuous sealing contact with the stationary portion at a sealing interface, the rotatable portion having a second channel formed therein on the axis of rotation and in substantially sealed fluid communication with the first channel, the first channel and second channel together forming a central channel on the axis of rotation through which the pressurized fluid for inflating a pneumatic tire may flow; and

a normally-closed check valve disposed in the central channel along the axis of rotation so as to allow the pressurized fluid to flow from the fluid pressure source in one direction through the central channel toward a pneumatic tire but not in the opposite direction toward the fluid pressure source, the normally-closed check valve being directly pneumatically actuatable by the pressurized fluid at the substantially constant predetermined fluid pressure from the pressure source while the rotary fluid connection is in substantially continuously-pressurized sealed fluid communication with the fluid pressure source, the normally-closed check valve being configured to open when fluid pressure in the pneumatic tire is lower than the substantially constant predetermined fluid pressure and close when the fluid pressure in the pneumatic tire substantially equals the substantially constant predetermined fluid pressure.

14. The rotary fluid connection of claim 13 , wherein the normally-closed check valve is disposed in one of the first channel of the stationary portion and the second channel of the rotatable portion.

15. The rotary fluid connection of claim 13 further comprising a rotatable tube, wherein the stationary portion comprises a stator having the first channel therein, and the rotatable portion comprises a tee body having the second channel therein, the stator and tee body in fluid communication through the rotatable tube, and the first channel of the stator, the tube and the second channel of the tee body together forming the central channel.

16. The rotary fluid connection of claim 13 , wherein the stationary portion comprises a shaft having the first channel therein, and the rotatable portion comprises a hubcap having the second channel therein, and the first channel of the shaft and the second channel of the hubcap together forming the central channel.

17. The rotary fluid connection of claim 13 , wherein the stationary portion comprises a shaft having the first channel therein, and the rotatable portion comprises a housing having a graphite element disposed therein, the housing and the graphite element having the second channel therein and being urged against the shaft to form a face seal, and the first channel of the shaft and the second channel of the housing and the graphite element together forming the central channel.

18. The rotary fluid connection of claim 13 , wherein the stationary portion comprises a stator having the first channel therein and the rotatable portion comprises a tube having a tee body together forming the second channel therein, and the first channel of the stator and the second channel of the tube and tee body together forming the central channel.

19. The rotary fluid connection of claim 13 , wherein the normally-closed check valve comprises an automobile tire valve.