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US 4,375,780 AGranted
Fail-fixed electrohydraulic servosystem
AssigneeGeneral Electric Company
InventorDonald Y. Davis
Life of this patent
Estimating the term…
Abstract
A fail-fixed electrohydraulic servosystem in which a variation from a predetermined range of electrical input to the servosystem results in the output of the system being fixed in position. Fixing-in-position is accomplished by either hydraulically or mechanically locking a linkage to the output arm of the servosystem. Provision is also made for controlled drift and manual adjustment of the output after it is fixed in position.
Claims11
A fail-fixed electrohydraulic servosystem for positioning a component to be controlled in response to an electrical input comprising:
- (1) an electrohydraulic servovalve including a translatably positionable servopiston having an end connectable to the component to be controlled, the position of said servopiston being proportional to the electrical input;
- (2) linkage means including a lever arm having first and second end portions and an intermediate portion disposed therebetween, said first end portion being pivotably connected to said servopiston and said intermediate portion being pivotably connected to a fulcrum member connected to a fixed member;
- (3) a rod having first and second end portions, said first end portion being pivotably connected to said second end portion of said lever arm;
- and
- (4) locking means cooperating with said second end portion of said rod for securing said rod in a fixed position when the electrical input varies from a predetermined range, thereby fixing said servopiston in a locked position, including:
- (a) a cylinder having a conduit providing communication of hydraulic fluid from a pressurized source thereof, containing a piston translatably actuatable in response to fluid pressure in said cylinder and receiving slidably said second end portion of said rod;
- (b) means including a valve in said conduit operative when the electrical input to said servosystem varies from said predetermined range to open said valve to effect a translatory actuation of said piston;
- and
- (c) a frictional locking member cooperating with said second end portion of said rod and said piston and effective for frictionally locking said rod relative to said cylinder upon actuation of said piston.
6 more elements
A fail-fixed electrohydraulic servosystem for positioning a component to be controlled in response to an electrical input comprising:
- (1) an electrohydraulic servovalve including a translatably positionable servopiston having an end connectable to the component to be controlled, the position of said servopiston being proportional to the electrical input;
- (2) linkage means including a lever arm having first and second end portions and an intermediate portion disposed therebetween, said first end portion being pivotably connected to said servopiston and said intermediate portion being pivotably connected to a fulcrum member connected to a fixed member;
- (3) a rod having first and second end portions, said first end portion being pivotably connected to said second end portion of said lever arm;
- and
- (4) locking means cooperating with said second end portion of said rod for securing said rod in a fixed position when the electrical input varies from a predetermined range, thereby fixing said servopiston in a locked position, including:
- (a) a cylinder having a conduit providing communication of hydraulic fluid from a pressurized source thereof, containing a piston having a portion defining a cam surface and being longitudinally actuatable in said cylinder in response to fluid pressure in said cylinder and receiving slidably said second end portion of said rod;
- (b) means including a solenoid-operated valve in said conduit and operative when the electrical input to said servosystem varies from said predetermined range to open said valve to effect actuation of said piston, and to close said valve when said electrical input to said servosystem is within said predetermined range;
- (c) a plurality of wedge-shaped locking members surrounding said rod and having cam surfaces cooperating with said cam surface on said piston and movable by said piston into frictional locking engagement with said rod when said piston is actuated;
- and
- (d) means effective for unlocking said rod relative to said cylinder when said electrical input to said servosystem is within said predetermined range;
- and
- wherein said fulcrum member is manually translatable with respect to said fixed member for thereby adjusting the position of said servopiston.
9 more elements
Dependencies are inferred from the claim text.