Patent ID: 8066598

Claim:
An apparatus for tensioning a chain, comprising: a chain drive tensioner assembly having: a tensioner body with a bore therein; a piston portion movable within the bore; and a shoe portion connected with the piston portion and configured to contact the chain; wherein the piston portion moves within the bore due to force from the chain to cause oil to leak from the bore with tensioning of the chain by the chain drive tensioner assembly decreasing as oil leakage from the bore increases; wherein the tensioner body defines a first passage in fluid communication with the bore and operable to leak oil from the bore in an amount that increases as temperature of the oil increases; and wherein the tensioner body defines a variable flow passage in fluid communication with the bore; an actuator movable in response to a predetermined temperature between a first temperature and a second temperature greater than the first temperature to at least partially block the variable flow passage; wherein the first passage is not blocked by movement of the actuator and is therefore operable to leak oil at both the first and second temperatures; and wherein the variable flow passage is operable to leak oil at the first temperature and the actuator at least partially prevents leakage of oil through the variable flow passage at the second temperature so that the variable flow passage provides a first amount of oil leakage from the bore at the first temperature and a second amount of oil leakage from the bore at the second temperature greater than the first temperature; and wherein viscosity of leaked oil is greater at the first temperature than at the second temperature and the second amount of oil leakage is lower than the first amount of oil leakage.