Control apparatus of control surface of aircraft

A control apparatus of a control surface of an aircraft comprising first and second servomechanisms each including:

• a hydraulic working oil source for supplying working oil under pressure;
• an actuator for driving said control surface, said actuator having a piston slidably received in a cylinder, and a piston rod fixed to said piston, the cylinder being divided into a pair of first and second cylinder chambers by said piston, the actuator being connected through said piston rod to said control surface;
• a servo valve for controlling said control surface said servo valve being shiftable between a first position thereof, in which said working oil is supplied to either one of said pair of cylinder chambers to change a driving direction of said actuator, and a second position, in which supply of said working oil to said actuator is interrupted to stop the drive of said actuator;
• a switch valve interposed between said hydraulic working oil source and said servo valve and shiftable between a first position thereof, in which said working oil from said hydraulic working oil source is supplied to said servo valve, and a second position thereof, in which the supply of said working oil is cut off;
• a bypass valve interposed between said servo valve and said actuator, actuated by means of a pilot pressure in said switch valve introduced thereto through a pilot conduit between said switch valve and said bypass valve, and shiftable between a first position thereof, so that when said switch valve is shifted to said first position thereof, said working oil from said servo valve is supplied to said actuator, and a second position thereof, so that when said switch valve is shifted to said second position, said working oil from said servo valve is cut off and said first and second cylinder chambers are held in fluid communication with each other through a bypass conduit connected to said bypass valve thereby releasing the control of said control surface;
• a control valve provided in said bypass conduit of said bypass valve and shiftable between a first position, in which the entire working oil in said bypass conduit is allowed to pass through said control valve so that said control surface becomes freely movable, and a second position thereof, in which said working oil in said bypass conduit is restricted so as to regulate the motion of said control surface connected to said piston rod of said actuator;
• and
• a control circuit for outputting to said switch valve a first control signal for cutting off the supply of said working oil and for outputting to said control valve a second control signal for shifting said control valve to said first position thereof and a third control signal for shifting said control valve to said second position thereof,
• whereby when either one of said servomechanisms is damaged, the control of said control surface by said damaged servomechanism being released by outputting said first control signal of said control circuit of said one damaged servomechanism to said switch valve of said one damaged servomechanism and outputting said second control signal of said control circuit of the other servomechanism to said control valve of said one damaged servomechanism, and
• whereby when both first and second servomechanisms are damaged, the free motion of said control surface being regulated by outputting said first control signal of said first servomechanism to said switch valve of said first servomechanism and said third control signal of said second servomechanism to said control valve of said first servomechanism and by outputting said first control signal of said second servomechanism to aid switch valve of said second servomechanism signal of said first servomechanism to said control valve of said second servomechanism.

A control apparatus of a control surface of an aircraft having at least two servomechanisms each including:

• a hydraulic working oil source for supplying working oil under pressure;
• an actuator for driving said control surface said actuator having a piston slidably received in a cylinder, and a piston rod fixed to said piston, the cylinder being divided into a pair of cylinder chambers by said piston, the actuator being connected through said piston rod to said control surface;
• a servo valve for controlling said control surface which is shiftable between a first position thereof, in which said working oil is supplied to either one of said pair of cylinder chambers to change a driving direction of said actuator, and a second position, in which supply of said working oil to said actuator is interrupted to stop the drive of said actuator;
• a switch valve interposed between said hydraulic working oil source and said servo valve and shiftable between a first position thereof, in which said working oil form said hydraulic working oil source is supplied to said servo valve, and a second position thereof, in which the supply of said working oil is cut off;
• a bypass valve interposed between said servo valve and said actuator, actuated by means of a pilot pressure in said switch valve introduced thereto through a pilot conduit between said switch valve and said bypass valve, and shiftable between a first position thereof, in which when said switch valve is shifted to said first position thereof, said working oil from said servo valve is supplied to said actuator, and a second position thereof, so that when said switch valve is shifted to said second position, said working oil from said servo valve is cut off and said first and second cylinder chambers are held in fluid communication with each other through a bypass conduit connected to said bypass valve in order to release the control of said control surface;
• a control valve provided in said bypass conduit of said bypass valve and shiftable between a first position, in which the entire working oil in said bypass conduit is allowed to pass through said control valve so that said control surface becomes freely movable, and a second position thereof, in which said working oil in said bypass conduit is restricted so as to regulate the motion of said control surface connected to said piston rod of said actuator;
• and
• a control circuit for outputting to said switch valve a first control signal for cutting off the supply of said working oil and for outputting to said control valve a second control signal for shifting said control valve to said first position thereof and a third control signal for shifting said control valve to said second position thereof;
• whereby when either one of said servomechanisms is damaged, the control of said control surface by said damaged servomechanism being released by outputting said first control signal of said control circuit of said one damaged servomechanism to said switch valve of said one damaged servomechanism and outputting said second control signal of said control circuit of the other servomechanism to said control valve of said one damaged servomechanism;
• and
• whereby when all said servomechanisms are damaged, the free motion of said control surface being regulated by shifting the control valve to the second position thereof in all said servomechanisms.