Dual piston actuator

摘要

A power transmitting component can include a friction clutch, hydraulic ram, and an actuator. The actuator can include first and second pistons, and a resilient member. The resilient member can translate the first piston to provide a high volume of fluid at low pressure to the ram when a pressure in a first chamber is less than a predetermined pressure and the second piston is translated in a first direction. The resilient member can compress between the first and second pistons to permit relative motion between the pistons when the pressure is equal to, or greater than, the predetermined pressure and the second piston is translated in the first direction. The second piston provides a low volume of fluid at high pressure to the ram when pressure in the first chamber is equal to, or greater than, the predetermined pressure and the second piston is translated in the first direction.

主权项

1. A power transmitting component comprising:
a friction clutch having a plurality of first clutch plates and a plurality of second clutch plates that are interleaved with the first clutch plates; a hydraulic ram coupled to the friction clutch, the hydraulic ram having a ram chamber and a ram piston that is movable in the ram chamber between a first ram position in which the ram piston is retracted relative to the first and second clutch plates, and a second ram position in which the ram piston is extended toward the first and second clutch plates to a greater extent than when the ram piston is in the first ram position; and an actuator including:
a first piston and cylinder, the first piston being received in the first cylinder, the first piston and cylinder defining a first chamber;a second piston and cylinder, the second piston being received in the second cylinder, the second piston and cylinder defining a second chamber in fluid communication with the ram chamber, the second piston defining a fluid passage fluidly coupling the first and second chambers;a valve body being movable between a first valve position wherein the fluid passage is open to permit fluid communication between the first and second chambers, and a second valve position wherein the valve body blocks the fluid passage to prevent fluid communication between the first and second chambers; anda drive mechanism configured to axially translate the second piston, and configured to axially translate the first piston when a pressure in the first chamber is less than a predetermined pressure and not translate the first piston when the pressure in the first chamber is equal to, or greater than, the predetermined pressure;wherein the valve body is prevented from moving to the second valve position and the first piston provides a first volume of fluid at a first pressure to the ram chamber when the drive mechanism translates the first piston in a first axial direction;wherein the valve body is permitted to move to the second valve position when the pressure in the first chamber is equal to, or greater than the predetermined pressure and the second piston is translated in the first axial direction;wherein the second piston provides a second volume of fluid at a second pressure to the ram chamber, the first volume of fluid being greater than the second volume of fluid, and the first pressure being less than the second pressure, when the valve body is in the second valve position and the second piston is translated in the first axial direction.