Flow Restricted Positioner Control Apparatus and Methods

A position control apparatus that maintains a component at a stationary position within a positioner range defined by two extremes, said apparatus able to reposition said component from said stationary position to a different stationary position within said positioner range, and said component capable of receiving an impulse force while in either of said stationary positions, said apparatus comprising:

• a positioner a positioner actuator, said actuator comprising a piston in a cylinder, said piston having a piston face area, said piston pressurized by a pressurized fluid, part of which is established in a pressurized fluid portion of said cylinder, and said pressurized fluid at a pressurized fluid pressure and generating a pressurized fluid force that acts against said piston in a first relative direction, wherein said piston divides said cylinder into said pressurized fluid portion and a vent cylinder portion, said vent cylinder portion vented to a vent pressure that is less than said pressurized fluid pressure, and
• said positioner actuator further comprising a mechanical biaser that generates a bias force that acts against said pressurized fluid force in a second relative direction, said second relative direction opposite said first relative direction,
• wherein, when said component is in any of said stationary positions, said pressurized fluid is at a controlled, stationary position fluid pressure that generates a controlled, stationary position pressurized fluid force that is opposed by and is equal to a stationary position, mechanical bias force,
• said position control apparatus further comprising at least one flow orifice that is in fluidic contact with said pressurized fluid, that has a cross-sectional area that is less than 1/2500th of said piston face area, and that is configured to oppose motion of said component induced by said impulse force,
• wherein, during application of said impulse force, when flow through said orifice reaches a threshold flow value, said flow orifice automatically, without monitoring any fluid or valve characteristic, limits said flow through said flow orifice to a constant value, said flow orifice thereby reducing motion induced by said impulse force, and
• wherein said positioner actuator is fluidicly linked in parallel with at least one other positioner actuator that each controls the position of a respective one of at least one other different component, such that said pressurized fluid is shared among all said positioner actuators.

A method for reducing impulse force induced motion of a component capable of receiving an impulse force and whose position is controlled by a position control apparatus, said method comprising the steps of:

• internally pressurizing componentry of said position control apparatus with a pressurized fluid at a controlled pressure, said position control apparatus comprising a positioner actuator that comprises a piston in a cylinder and that is configured to control the position of said component capable of receiving an impulse force, wherein said piston has a piston face area;
• establishing a flow orifice so as to produce an opposition force that opposes impulse force induced motion of said component capable of receiving an impulse force, said flow orifice have a cross-sectional area that is less than 1/2500th of said piston face area;
• controllably moving said component to a desired stationary position;
• balancing a force generated by said pressurized fluid with a mechanical bias force so as to maintain said component in said desired stationary position;
• receiving, during an impulse event, an impulse force onto said component capable of receiving an impulse force;
• then limiting flow through said flow orifice to constant value, wherein said constant value is selected from the group consisting of non-zero value and zero;
• and
• reducing impulse force induced motion of said component capable of receiving an impulse force.