Gear assembly and a door mount mechanism including the same

1. A gear assembly comprising:

a planetary gear set which includes

a sun gear,

at least one planet gear meshing with said sun gear,

a carrier supporting said at least one planet gear, and

an outer ring gear meshing with said at least one planet gear; and

a clutch which is operable to engage with and disengage from said planetary gear set to enable said planetary gear set to switch between a first mode and a second mode,

wherein said clutch is an electromechanical solenoid which includes:

a movable armature,

an electromagnetically inductive coil which is wound around said movable armature, which produces an induced magnetic field when provided with an electric current for applying forces to control extension and retraction of said movable armature relative to said electromagnetically inductive coil for engaging or disengaging said movable armature from said carrier, and

a sensor which detects the extension and retraction of said movable armature,

wherein said carrier is formed with at least one engagement part, said electromechanical solenoid is operable to engage with said engagement part for enabling said planetary gear set to operate in the first mode, and is operable to disengage from said engagement part for enabling said planetary gear set to operate in the second mode

said movable armature is controlled to retract so as to disengage from said engagement part of said carrier to switch said planetary gear set from the first mode to the second mode, and

during retraction of said movable armature said carrier is driven by said at least one planet gear and said sun gear to rotate away from said movable armature of said electromechanical solenoid to prevent friction between said movable armature and said engagement part during retraction of said movable armature.

2. The gear assembly according to claim 1 , wherein, in the first mode, said clutch engages with said carrier to limit movement of said carrier relative to said clutch such that rotation of said sun gear drives said at least one planet gear to spin on an axis of said at least one planet gear without revolving around said sun gear so as to drive rotation of said outer ring gear.

3. The gear assembly according to claim 1 , wherein, in the second mode, said clutch disengages from said carrier to allow movement of said carrier relative to said clutch such that said at least one planet gear is spinnable on an axis of said at least one planet gear and is revolvable around said sun gear so as to allow free rotation of said outer ring gear.

4. The gear assembly according to claim 1 , wherein said electromechanical solenoid further includes:

an electrically conductive housing which accommodates said electromagnetically inductive coil therein, which is formed with an opening for permitting movable extension of said movable armature therethrough into said electrically conductive housing, and which is grounded; and

a dielectric cover which covers said opening of said electrically conductive housing, which is formed with a hole for the extension and re traction of said movable armature therethrough, and which provides electrical insulation between said movable armature and said opening of said electrically conductive housing;

said sensor including an electrically conductive member which is disposed on said dielectric cover, which is electrically connected to said movable armature, and which is applied with a voltage;

when said movable armature is retracted into said electrically conductive housing and said movable armature is in electrical contact with a bottom of said electrically conductive housing such that said electrically conductive member is grounded, variation in voltage of said electrically conductive member is measured so as to determine the retraction of said movable armature; and

when said movable armature is extended from said electrically conductive housing and said movable armature is not in electrical contact with the bottom of said electrically conductive housing, said electrically conductive member is measured to maintain at the voltage so as to determine the extension of said movable armature.

5. The gear assembly according to claim 1 , wherein said electromechanical solenoid further includes:

an electrically conductive housing which accommodates said electromagnetically inductive coil therein, and which is formed with an opening for permitting movable extension of said movable armature therethrough into said electrically conductive housing;

a cover which covers said opening of said electrically conductive housing, and which is formed with a hole for the extension and retraction of said movable armature therethrough; and

a spring which has two ends abutting against said cover and a stopper member fixed onto said movable armature, respectively;

when said movable armature is retracted into or extended from said electrically conductive housing such that a length of said spring is changed, said sensor measures variation in electrical resistance of said spring so as to determine one of the retraction and extension of said movable armature.

6. The gear assembly according to claim 1 , wherein said electromechanical solenoid further includes:

an electrically conductive housing which accommodates said electromagnetically inductive coil therein, and which is formed with an opening for permitting movable extension of said movable armature therethrough into said electrically conductive housing;

said sensor including a strain gage which has one end attached to said movable armature and another end attached to said electrically conductive housing; and

when said movable armature is retracted into or extended from said electrically conductive housing such that said strain gage is deformed, said sensor measured variation in electrical resistance of said strain gage so as to determine one of the retraction and extension of said movable armature.

7. A door mount mechanism adapted to be mounted onto a door for rotating a thumb turn of a door lock which is mounted on the door, said door mount mechanism comprising:

a casing having a door-mounting end that is adapted for abutting against the door, and defining a receiving space that is adapted for receiving the door lock, and that has an opening at said door-mounting end and adapted for extension of the door lock therethrough;

a rotatable component coupled rotatably to said casing;

an intermediate coupling connected co-rotatably to said rotatable component, and adapted for driving rotation of the thumb turn of the door lock such that the thumb turn is co-rotatable with said rotatable component; and

an actuating unit controllable to actuate rotation of said rotatable component, and including a motor and a gear assembly, said gear assembly including

a planetary gear set which is driven rotatably by said motor and which includes:

a sun gear;

at least one planet gear meshing with said sun gear;

a carrier supporting said at least one planet gear; and

an outer ring gear meshing with said at least one planet gear, and

a clutch which is operable to engage with and disengage from said planetary gear set to enable said planetary gear set to switch between a first mode and a second mode;

wherein said clutch is an electromechanical solenoid which includes:

a movable armature,

an electromagnetically inductive coil which is wound around said movable armature, which produces an induced magnetic field when provided an electric current for applying forces to control extension and retraction of said movable armature relative to said electromagnetically inductive coil for engaging or disengaging said movable armature from said carrier, and

a sensor which detects the extension and retraction of said movable armature;

wherein said carrier is formed with at least one engagement part, said electromechanical solenoid is operable to engage with said engagement part for enabling said planetary gear set to operate in the first mode, and the electromechanical solenoid is operable to disengage from said engagement part for enabling said planetary gear set to operate in the second mode,

said movable armature is controlled to retract so as to disengage from said engagement part of said carrier to switch said planetary gear set from the first mode to the second mode, and

during retraction of said movable armature, said carrier is driven by said at least one planet gear and said sun gear to rotate away from said movable armature of said electromechanical solenoid to prevent friction between said movable armature and said engagement part.

8. The door mount mechanism according to claim 7 , wherein, in the first mode, when said motor is not operating and is not driving rotation of said sun gear, rotation of said rotatable component is hindered by rotational resistance of said motor.

9. The door mount mechanism according to claim 7 , wherein, in the second mode, said clutch disengages from said carrier to allow movement of said carrier relative to said clutch such that said at least one planet gear is spinnable on an axis of said at least one planet gear and is revolvable around said sun gear so as to allow free rotation of said outer ring gear.

10. The door mount mechanism according to claim 7 , wherein said electromechanical solenoid further includes:

an electrically conductive housing which accommodates said electromagnetically inductive coil therein, which is formed with an opening for permitting movable extension of said movable armature therethrough into said electrically conductive housing, and which is grounded; and

a dielectric cover which covers said opening of said electrically conductive housing, which is formed with a hole for the extension and retraction of said movable armature therethrough, and which provides electrical insulation between said movable armature and said opening of said electrically conductive housing;

said sensor including an electrically conductive member which is disposed on said dielectric cover, which is electrically connected to said movable armature, and which is applied with a voltage;

when said movable armature is retracted into said electrically conductive housing and said movable armature is in electrical contact with a bottom of said electrically conductive housing such that said electrically conductive member is grounded, variation in voltage of said electrically conductive member is measured so as to determine the retraction of said movable armature; and

when said movable armature is extended from said electrically conductive housing and said movable armature is not in electrical contact with the bottom of said electrically conductive housing, said electrically conductive member is measured to maintain at the voltage so as to determine the extension of said movable armature.

11. The door mount mechanism according to claim 7 , wherein said electromechanical solenoid further includes:

an electrically conductive housing which accommodates said electromagnetically inductive coil therein, and which is formed with an opening for permitting movable extension of said movable armature therethrough into said electrically conductive housing;

a cover which covers said opening of said electrically conductive housing, and which is formed with a hole for the extension and retraction of said movable armature therethrough; and

a spring which has two ends abutting against said cover and a stopper member fixed onto said movable armature, respectively;

when said movable armature is retracted into or extended from said electrically conductive housing such that a length of said spring is changed, said sensor measures variation in electrical resistance of said spring so as to determine the retraction and extension of said movable armature.

12. The door mount mechanism according to claim 7 , wherein said electromechanical solenoid further includes:

an electrically conductive housing which accommodates said electromagnetically inductive coil therein, and which is formed with an opening for movable extension of said movable armature therethrough into said electrically conductive housing;

said sensor including a strain gage which has one end attached to said movable armature and another end attached to said electrically conductive housing; and

when said movable armature is retracted into or extended from said electrically conductive housing such that said strain gage is deformed, said sensor measured variation in electrical resistance of said strain gage so as to determine the retraction and extension of said movable armature.

13. The door mount mechanism according to claim 7 , wherein said rotatable component is formed with gear teeth for meshing with said outer ring gear.

14. The door mount mechanism according to claim 7 , wherein, in the first mode, said clutch engages with said carrier to limit movement of said carrier relative to said clutch such that rotation of said sun gear drives said at least one planet gear to spin on an axis of said at least one planet gear without revolving around said sun gear so as to drive rotation of said outer ring gear.