System for maintaining a pressing force by the combined action of two members

1. An aircraft electromechanical braking system comprising:

braking control means ( 10 ) and at least one electromechanical brake ( 1 ) fitted to at least one braked wheel ( 3 ) of the aircraft,

wherein the brake ( 1 ) is fitted with friction members ( 2 ) and with at least one electromechanical actuator ( 4 ) having a pusher ( 6 ) suitable for being moved by means of an electric motor ( 7 ) in order to selectively apply a pressing force against the friction members ( 2 ), the actuator ( 4 ) also having a blocking member ( 8 ) for blocking the pusher ( 6 ) in position,

wherein the control means ( 10 ) is configured to cause the braking system to operate at least in a controlled mode in which the electric motor ( 7 ) is controlled to selectively apply a pressing force in response to a braking setpoint, or in a parking mode in which the motor ( 7 ) is controlled to bring the pusher ( 6 ) into a position in which it exerts a parking force on the friction members ( 2 ), and then the blocking member is activated and the motor is deactivated, and

wherein the control means ( 10 ) also is configured to cause the braking system to operate in a combined mode, in which:

first, the motor ( 7 ) is activated to bring the pusher ( 6 ) into a position in which it exerts a given holding force,

second, the given holding force is maintained solely by the blocking member, and

then activation of the motor ( 7 ) is maintained,

whereby the motor alone develops an additional pressing force, a total pressing force against the friction members ( 2 ) being the sum of the given holding force and the additional pressing force.

2. The braking system according to claim 1 , characterized in that the control means ( 10 ) are adapted:

to control the electric motor ( 7 ) to bring the pusher into a position in which it exerts a target pressing force greater than the holding force, the blocking member ( 8 ) being inactive;

to activate the blocking member ( 8 ) to block the pusher ( 6 ) of the electromechanical actuator ( 4 ) when the pusher exerts a force equal to the holding force;

to reduce the force generated by the motor; and

to maintain activation of the motor in order to enable the pusher ( 6 ) to develop a force equal to the target force.

3. The braking system according to claim 1 , characterized in that the control means ( 10 ) are also adapted, in combined mode, to adjust the position of the pusher when the electric current consumed by the electric motor ( 7 ) becomes greater than a maximum current threshold (Smax) or less than a minimum current threshold (Smin).

4. The braking system according to claim 3 , characterized in that an adjustment in the position of the pusher consists in:

deactivating the blocking member ( 8 );

controlling the electric motor ( 7 ) to bring the pusher into a position in which it exerts the target pressing force; and

activating the blocking member ( 8 ), while maintaining activation of the motor in order to enable the pusher ( 6 ) to develop a force equal to the target force, and then reducing the force generated by the motor.

5. The braking system according to claim 1 , characterized in that the combined mode is activated by detecting a command for braking in parking mode that is simultaneous with thrust from a propulsion engine of the aircraft, or by detecting a command for a parking braking mode to generate a pressing force greater than a predefined force threshold, or by the pilot taking action on an actuator member.

6. The braking system according to claim 1 , characterized in that the electricity consumption of the motor ( 7 ) is limited by a predefined current threshold (Isat).

7. The braking system according to claim 2 , characterized in that the combined mode is activated by detecting a command for braking in parking mode that is simultaneous with thrust from a propulsion engine of the aircraft, or by detecting a command for a parking braking mode to generate a pressing force greater than a predefined force threshold, or by the pilot taking action on an actuator member.

8. The braking system according to claim 2 , characterized in that the electricity consumption of the motor ( 7 ) is limited by a predefined current threshold (Isat).

9. The braking system according to claim 3 , characterized in that the combined mode is activated by detecting a command for braking in parking mode that is simultaneous with thrust from a propulsion engine of the aircraft, or by detecting a command for a parking braking mode to generate a pressing force greater than a predefined force threshold, or by the pilot taking action on an actuator member.

10. The braking system according to claim 3 , characterized in that the electricity consumption of the motor ( 7 ) is limited by a predefined current threshold (Isat).

11. The braking system according to claim 4 , characterized in that the combined mode is activated by detecting a command for braking in parking mode that is simultaneous with thrust from a propulsion engine of the aircraft, or by detecting a command for a parking braking mode to generate a pressing force greater than a predefined force threshold, or by the pilot taking action on an actuator member.

12. The braking system according to claim 4 , characterized in that the electricity consumption of the motor ( 7 ) is limited by a predefined current threshold (Isat).