Vertical actuator having a gravity compensation device
A vertical actuator has a stationary part that includes an upper part made of magnetic material which is magnetically separated from a yoke which bears a coil. The upper magnetic part generates an overall reluctance force on the movable part of the actuator which, over the entire functional range of the actuator, is slightly greater than the gravitational force. When the coil is not energized, the movable part has a position of stable equilibrium which is in the upper section of this functional range.
1. A vertical actuator, comprising:
a stationary part including a magnet yoke and at least one coil supported by the yoke; and
a movable part including at least one permanent magnet and movably disposed in an interior of the yoke;
wherein the stationary part includes an upper magnetic part formed of a magnetic material, the upper magnetic part arranged above the movable part, the upper magnetic part and the yoke magnetically separated from each other by a part formed of a non-magnetic material.
2. The vertical actuator according to claim 1 , wherein the permanent magnet is axially magnetized, the movable part including a device configured to close the magnetic field, the device, together with the yoke, forming a magnetic circuit adapted to couple the magnetic field to the at least one coil.
3. The vertical actuator according to claim 2 , wherein the device includes a magnetic disk provided on each of an upper end and a lower end of the permanent magnet.
4. The vertical actuator according to claim 1 , wherein the permanent magnet is axially magnetized, the movable part including a device configured to close the magnetic field, the device, together with the yoke, forming a magnetic circuit that couples the magnetic field to the at least one coil.
5. The vertical actuator according to claim 1 , wherein the permanent magnet is axially magnetized, the movable part including means for closing the magnetic field, the means, together with the yoke, forming a magnetic circuit that couples the magnetic field to the at least one coil.
6. The vertical actuator according to claim 5 , wherein the means includes a magnetic disk provided on each of an upper end and a lower end of the permanent magnet.
7. The vertical actuator according to claim 1 , wherein the upper magnetic part includes a metal pin having an axis that coincides with a central axis of the movable part.
8. The vertical actuator according to claim 1 , wherein the upper magnetic part and the yoke are arranged to direct a reluctance force exerted on the movable part upward, and over an entire functional range of the vertical actuator, the reluctance force having a value slightly greater than a force of gravity to which the movable part is subjected, upon an absence of a current supply to the at least one coil, the vertical actuator has, for the movable part, a point of stable equilibrium located at least one of (a) in an upper section and (b) above the functional range of the vertical actuator.
9. The vertical actuator according to claim 3 , wherein the magnetic disk provided on the upper end of the permanent magnet includes a recess adapted to receive a portion of the upper magnetic part.
10. The vertical actuator according to claim 3 , wherein the upper magnetic part includes a metal pin, the magnetic disk provided on the upper end of the permanent magnet includes a recess adapted to receive a portion of the metal pin.
11. The vertical actuator according to claim 1 , wherein the part formed of the non-magnetic material is arranged as cover of the vertical actuator.
12. The vertical actuator according to claim 1 , wherein the upper magnetic part is supported above the movable part by the part formed of the non-magnetic material.