Eddy current brake appratus, systems, and related methods for use with actuators having a fail-safe mode of operation
Aspects of the disclosure provide an electric actuator including a first driving source coupled to an output through a first pathway created by a transmission, a second driving source coupled to the output though a second pathway created by the transmission that, upon the electric actuator losses electrical power to the electric actuator, causes the output to be positioned at a fail-safe position, a differential coupled to the first driving source and the second driving source through a third pathway created by the transmission to store energy from the first driving source in the second driving source, and an eddy current brake coupled to the output through the transmission that reduces a speed at which the second driving source moves the output to the fail-safe position.
1. An electric actuator, comprising:
a first driving source coupled to an output through a first pathway created by a transmission;
a second driving source coupled to the output through a second pathway created by the transmission that, upon loss of electrical power to the electric actuator, causes the output to be positioned at a fail-safe position;
a differential coupled to the first driving source and the second driving source through a third pathway created by the transmission to store energy from the first driving source in the second driving source; and
an eddy current brake coupled to the output through the transmission that reduces a speed at which the second driving source moves the output to the fail-safe position.
2. The electric actuator of claim 1 , wherein the eddy current brake includes:
a support member fixedly coupled to the electric actuator;
a magnet portion supported by the support member including one or more permanent magnets creating a magnetic field; and
a conductor portion in the magnetic field adjacent the magnet portion and connected to a transmission shaft to receive torque from the transmission shaft, the conductor portion rotatable relative to the magnetic field about an axis to generate a braking force that is applied to the output through transmission.
3. The electric actuator of claim 2 , wherein the magnet portion is adjustably coupled to the support member such that the magnet portion is movable relative to the conductor portion to change the braking force.
4. The electric actuator of claim 3 , wherein the magnet portion includes a body holding the one or more permanent magnets and defining a slot that extends through the body in which a fastener connecting the body to the support member is positioned.
5. The electric actuator of claim 2 , further including a gear train coupling the conductor portion of the eddy current brake to an output member of the second driving source, the gear train including a plurality of gears connected together structured to increase an angular speed of the conductor portion relative to an angular speed of the output member.
6. The electric actuator of claim 1 , further including an electromagnetic brake coupled to the second driving source through the transmission that, when engaged, prevents the second driving source from releasing the energy stored therein, wherein the eddy current brake and the electromagnetic brake are proximate to each other and connected to a same transmission shaft.
7. An apparatus, comprising:
an actuator configured to change from a normal operating mode to a fail-safe operating mode upon loss of electrical power to the actuator, the actuator including:
a differential including a first input member, a second input member, and an output member operatively coupled together to form part of a transmission in the actuator;
an output connected to the output member of the differential that is movable between different positions including a fail-safe position;
a first driving source connected to the first input member of the differential configured to drive the output when the actuator is in the normal operating mode;
a second driving source connected to the second input member of the differential configured to drive the output when the actuator is in the fail-safe operating mode; and
an eddy current brake connected to the differential that is driven by the second driving source when the actuator is in the fail-safe operating mode to generate a braking force, the eddy current brake configured to apply the braking force to the output through the transmission while the output moves to the fail-safe position.
8. The apparatus of claim 7 , wherein the eddy current brake includes at least two magnets and at least one disk-shaped conductor between the at least two magnets that is supported by a transmission shaft defining a rotation axis of the disk-shaped conductor.
9. The apparatus of claim 8 , wherein the eddy current brake includes a body holding the at least two magnets and at least one fastener adjustably coupling the body to a part of the actuator adjacent the disk-shaped conductor, movement of the body relative to the disk-shaped conductor causing the eddy current brake to change between a high drag state associated with a first characteristic relating to drag of the eddy current brake and a low drag state associated with a second characteristic relating to drag of the eddy current brake different from the first characteristic.
10. The apparatus of claim 7 , wherein the actuator includes a gear train creating a pathway through which the second driving source and the eddy current brake are coupled to the second input member of the differential.
11. The apparatus of claim 10 , wherein the actuator includes an electromagnetic brake coupled to the second input member of the differential through the pathway that is configured to lock the second input member and the gear train to prevent the second driving source from releasing energy stored therein.
12. A method for driving an electric actuator, comprising:
supplying electrical power to a first driving source coupled to a differential driving a transmission coupled to an output or a second driving source;
disengaging an electromagnetic brake of the electric actuator coupled to the second driving source to enable the differential to transfer energy through the transmission from the first driving source to the second driving source;
storing energy in the second driving source from the first driving source;
engaging the electromagnetic brake to prevent the second driving source from releasing energy stored therein;
disengaging the electromagnetic brake upon loss of the electrical power to enable the differential to transfer energy through the transmission from the second driving source to the output and an eddy current brake of the electric actuator; and
generating, via the eddy current brake, a braking force that is applied to the output through the transmission to reduce a speed at which the second driving source moves the output to a fail-safe position.
13. The method of claim 12 , further including adjusting a magnet portion of the eddy current brake supported by the electric actuator relative to a conductor portion of the eddy current brake coupled to a transmission shaft to change the braking force.