HYDRAULIC BELT TENSIONER CONSTRUCTION

摘要

A hydraulic tensioning device for maintaining a predetermined amount of tensioning force on an endless drive belt of a vehicle accessories drive system. A housing is mounted in a fixed position on the engine in close proximity to the drive belt. A shaft is movably mounted within the housing by an elastomer block which biases the shaft in a belt tensioning rotational direction. A lever extends outwardly from the housing and is integrally connected to the shaft for pivotal movement upon rotation of the shaft. An expandable bladder or actuator is mounted in the housing and is engageable with the shaft and pivots the rotor and lever toward a belt tensioning direction when the bladder is expanded by hydraulic fluid. A hydraulic fluid supply and pump assembly supplies fluid under pressure to inflate the bladder. An idler pulley drivingly engages the fluid pump and is driven by the endless drive belt for actuating the pump. The elastomer block applies a pretensioning force on the drive belt with the hydraulically inflatable bladder supplying the major portion of the tensioning force when the vehicle engine is running. In one form of the invention, the fluid supply and pump assembly is mounted in the housing and the lever either moves a pivotally mounted vehicle accessory or moves an idler pulley into belt engagement to tension the belt. In another embodiment, the fluid supply and pump assembly is mounted on the extended end of the lever in engagement with an idler pulley which both tension the belt and drives the fluid pump with the elastomer block, bladder and shaft being mounted in a fixed position on the engine.