| 摘要 |
<p>(Case No. 59-1A) A hydraulic tensioning device for maintaining a predetermined amount of tensioning force on an endless drive bolt for the vehicle accessories drive system. A hydraulic cylinder is adapted to be mounted in a fixed position with respect to the vehicle engine and is operatively connected to the lowpressure hydraulic fluid system of the engine. A bellcrank mechanism is pivotally mounted on the cylinder and has a boltengaging idler pulley rotatably mounted on an extended end of one of the levers. The other lever is operatively engaged by the cylinder piston which moves the idler pulley into tensioning engagement with the drive belt. The cylinder has a plurality of discs mounted in a spaced relationship on the piston rod for imparting movement to the rod when acted upon by hydraulic fluid. Each disc forms a movable forward wall of a separate hydraulic subchamber located within the cylinder. A hollow bore is formed in the rear portion of the piston rod to provide a fluid passage between the spaced subchambers. The discs and associated subchambers enable a sufficiently large force to be exerted on the piston rod for actuation of the bellcrank from the low pressure of the engine lubricating system. A check valve is provided in the incoming hydraulic fluid passage of the cylinder and keeps those portions of each cylinder subchambers which are located behind the piston discs filled with hydraulic fluid to maintain a constant predetermined tensioning force on the belt without regard to the operating condition of the engine, and to provide a shock-absorbing damping action for the idler pulley.</p> |
