Air maintenance tire assembly

Abstract

A pumping device is used with a pneumatic tire mounted on a tire rim to keep the pneumatic tire from becoming underinflated. The pumping device includes a housing attached to the tire rim, a dynamic mass mechanically confined to linear movement relative to the housing and the tire rim, the dynamic mass moving in response to shock loads transferred from the tire rim to the dynamic mass and pumping ambient air into the housing, an intake port for ambient air to enter the housing, and an exhaust port for forcing pressurized air into a tire cavity of the pneumatic tire for restoring air loss from an inflation volume within the tire cavity.

What is claimed: 
     
         1 . A pumping device for use with a pneumatic tire mounted on a tire rim to keep the pneumatic tire from becoming underinflated, the pumping device comprising:
 a housing attached to the tire rim;   a dynamic mass mechanically confined to linear movement relative to the housing and the tire rim, the dynamic mass moving in response to shock loads transferred from the tire rim to the dynamic mass and pumping ambient air into the housing;   an intake port for ambient air to enter the housing; and   an exhaust port for forcing pressurized air into a tire cavity of the pneumatic tire for restoring air loss from an inflation volume within the tire cavity.   
     
     
         2 . The pumping device as set forth in  claim 1  wherein the dynamic mass is mechanically confined to radial movement relative to the pneumatic tire. 
     
     
         3 . The pumping device as set forth in  claim 1  wherein the dynamic mass changes position corresponding to a shock loads from a contact surface to the pneumatic tire. 
     
     
         4 . The pumping device as set forth in  claim 1  wherein a plane about which the dynamic mass moves is coplanar with a rotational plane of the tire rim. 
     
     
         5 . The pumping device as set forth in  claim 1  wherein movement of the dynamic mass transfers work energy to air pressure in the housing. 
     
     
         6 . The pumping device as set forth in  claim 1  further including a first check valve disposed proximate to the intake port for preventing air from flowing out of the housing. 
     
     
         7 . The pumping device as set forth in  claim 6  further including a second check valve disposed proximate to the exhaust port for preventing air from flowing out of the tire cavity and into the housing. 
     
     
         8 . The pumping device as set forth in  claim 7  further including a biasing element for returning the housing from a high volume intake condition to a low volume exhaust condition. 
     
     
         9 . The pumping device as set forth in  claim 8  wherein the first check valve and the second check valve are self checking ball-type check valves. 
     
     
         10 . The pumping device as set forth in  claim 1  further including a gear rotating to pump pressurized air from the housing and forcing pressurized air into the tire cavity. 
     
     
         11 . The pumping device as set forth in  claim 10  wherein the housing receives ambient air from an exterior of the housing and exhausts pressurized air into the tire cavity simultaneously. 
     
     
         12 . The pumping device as set forth in  claim 1  further including a gear rotated by movement of the dynamic mass. 
     
     
         13 . The pumping device as set forth in  claim 12  further including a biasing member for restoring an actuation cam to an initial position. 
     
     
         14 . The pumping device as set forth in  claim 1  further including a slot arm rotated by movement of the dynamic mass. 
     
     
         15 . The pumping device as set forth in  claim 1  further including two coaxial gears rotated by movement of the dynamic mass. 
     
     
         16 . The pumping device as set forth in  claim 1  further including a second housing attached to the tire rim diametrically opposite the first housing. 
     
     
         17 . The pumping device as set forth in  claim 16  wherein the pumping device also restores air loss from an inflation volume within a second tire cavity of a second pneumatic tire. 
     
     
         18 . The pumping device as set forth in  claim 1  further including two springs for returning the dynamic mass to a neutral position. 
     
     
         19 . The pumping device as set forth in  claim 18  further including an additional spring for returning a cam to an initial position. 
     
     
         20 . The pumping device as set forth in  claim 1  further including two slot arms for rotating an actuation cam in a single direction.