Quasi-open loop hydraulic ram incremental actuator with power conserving properties

Apparatus aboard an aircraft for positioning a component of the aircraft, capable of accepting a digital command, comprising:

• a balance piston linear hydraulic ram comprising a cylinder, a balanced piston within said cylinder dividing the cylinder into first and second expansible chambers on opposite sides of the piston;
• and
• means for incrementally driving said ram comprising:
• a reversible positive displacement pumping means operable in one direction to transfer hydraulic fluid from the first expansible chamber of said ram to the second expansible chamber of said ram, and operable in the opposite direction to transfer hydraulic fluid from the second chamber to the first chamber;
• and
• means for incrementally driving said rotary positive displacement pumping means, comprising;
• hydraulic motoring means drivenly connected to said positive displacement pumping means, said hydraulic motoring means comprising a plurality of cylinders, pistons within said cylinders, and means operable in response to sequenced pressurization of the cylinders, said attendant piston movement, to apply driving forces to pumping means;
• distributor valve means including a rotary control member and port means controlled by rotation of said rotary control member for communicating hydraulic pressure to a group of said cylinders which are a series while venting the rest of said cylinders to a return line;
• means for generating electrical digital command pulse signals;
• and;
• an electric stepping motor operable by said digital command pulse signals to rotate in increments, and including a rotary output connected to the rotary control member of the distributor valve means,
• with rotation of said rotary control member sequencing pressurization by progressively adding a cylinder to the forward edge of the pressurized group of cylinders and removing a cylinder from the trailing edge of the pressurized group of cylinders, to in that manner deliver driving pulses of hydraulic pressure to the hydraulic motoring means, with the pistons of each new group of pressurized cylinders functioning to drive the pumping means into a new position of equilibrium and then hold it in such position until there is another change in the makeup of the pressurized group of cylinders,
• whereby an increment of displacement occurs in direct response to each command pulse that is received by the stepping motor, attended by an increment of fluid transfer by the displacement means, and a corresponding increment of linear movement of the ram and an aircraft component positioned by it.

An electrohydraulic mechanism, comprising:

• an electric stepping motor operable by digital command signals to rotate in increments, and including a rotary output;
• pumping means comprising a plurality of cylinders, and pistons within said cylinders movable axially;
• hydraulic motoring means including a plurality of cylinders, pistons within said cylinders, and means operable in response to sequenced pressurization of the cylinders, and attendant piston movement, to apply driving forces to the pistons of said pumping means;
• distributor valve means including a rotary control member and port means controlled by rotation of said rotary control member for communicating hydraulic pressure to a group of said motoring means cylinders which are in series while venting the rest of said cylinders;
• means connecting the rotary output of the electric stepping motor to the rotary control member of the distributor valve means;
• and
• valve means for said pumping cylinders, communicating each pumping cylinder with a hydraulic fluid inlet port during retraction of the pistons and with an outlet port during extension of the pistons.

Apparatus for effecting incremental drive of a balanced piston hydraulic ram, comprising:

• a balanced piston hydraulic ram having a first expansible chamber on one side of the balanced piston and a second expansible chamber on the opposite side of the piston;
• a reversible positive displacement means operable in one direction to transfer hydraulic fluid from the first expansible chamber to the second expansible chamber, and operable in the opposite direction to transfer hydraulic fluid from the second chamber to the first chamber;
• and
• means for effecting incremental operation of said positive displacement means, comprising:
• hydraulic motoring means drivingly connected to said positive displacement means, said hydraulic motoring means comprising a plurality of cylinders, pistons within said cylinders, and means operable in response to sequenced pressurization of the cylinders, and attendant piston movement, to apply a driving force to said reversible positive displacement means;
• distributor valve means including a rotary control member and port means controlled by rotation of said rotary control member for communicating hydraulic pressure to a group of said cylinders which are in series while venting the rest of said cylinders to a return line;
• means for generating electrical digital command pulse signals;
• and
• an electric stepping motor operable by said electrical digital command pulse signals to rotate in increments, and including a rotary output connected to the rotary control member of the distributor valve means,
• with rotation of said rotary control member sequencing pressurization by progressively adding a cylinder to the forward edge of the pressurized group of cylinders and removing a cylinder from the trailing edge of the pressurized group of cylinders, to in that manner deliver driving pulses of hydraulic pressure to the hydraulic motoring means, with the pistons of each new group of pressurized cylinders functioning to drive the positive displacement means into a new position of equilibrium and then hold it in such position until there is another change in the make-up of the pressurized group of cylinders,
• whereby an increment of movement of the positive displacement means occurs in direct response to each command pulse that is received by the stepping motor, attended by an increment of fluid transfer between the expansible chambers of the ram and a corresponding increment of linear movement of the hydraulic ram.