Side door opening and closing apparatus for automobile

1. An opening and closing device for a side door configured to enable a door of a vehicle to be automatically opened and closed with respect to a vehicle body, the opening and closing device comprising:

a housing configured to be fixedly disposed in the door and having a receiving space therein;

a drive motor disposed in the receiving space of the housing and comprising a drive shaft;

a worm gear connected to the drive shaft and configured to rotate together with the drive shaft;

a worm wheel configured to engage with the worm gear and rotatable by receiving a rotational force from the worm gear;

a pinion gear configured to rotate in conjunction with the worm wheel; and

a rack gear having one end configured to be hinged to the vehicle body, the rack gear being configured to be engaged with the pinion gear to convert rotational motion of the pinion gear into linear motion,

wherein the worm gear has a reversible structure, wherein the worm gear is rotatable by receiving a rotational force of the worm wheel when the worm wheel rotates, so that, when the drive motor rotates in an automatic mode, the worm gear is configured to rotate the worm wheel, and when a user manually rotates the door in a manual mode, the worm gear is rotatable by the rotating worm wheel,

wherein the drive motor is connected to one end of the worm gear, and a brake configured to stop rotation of the worm gear is disposed at another end of the worm gear, and

wherein the brake is configured to remove a braking force when an electrical signal is applied to the brake and to apply the braking force when the electrical signal is removed from the brake.

2. The opening and closing device of claim 1 , wherein a lead angle of a thread of the worm gear ranges from 5° to 15°.

3. The opening and closing device of claim 1 , further comprising

a load sensor configured to detect a manual opening or closing of the door by the user; and

a controller connected to the load sensor and configured to transmit the electrical signal to the brake when the load sensor detects the manual opening or closing of the door by the user,

wherein, when the load sensor detects that the user manually opens or closes the door in the manual mode, the controller connected to the load sensor is configured to apply the electrical signal to the brake to remove the braking force.

4. The opening and closing device of claim 1 , wherein

a concave groove having a shape corresponding to the pinion gear is defined at a center of the worm wheel, and a part of the pinion gear is disposed in the concave groove so that the pinion gear is configured to rotate in conjunction with the worm wheel, and

a gear shaft supporting the pinion gear is disposed in a center of the pinion gear while being rotationally fixed to the housing.

5. The opening and closing device of claim 4 , wherein

the worm wheel comprises a wheel body having gear teeth disposed at a circumferential edge of the wheel body, and

a central protrusion protruding from one surface of the wheel body, the central protrusion having the concave groove defined at a center of the central protrusion, and

wherein a central hole is defined in the housing at a position corresponding to the central protrusion, and a sealing ring is fixedly disposed at a circumferential edge of the central hole to maintain airtightness.