Driving apparatus for swing door

1 . A driving apparatus for a swing door, the driving apparatus comprising:

a drive shaft that is linearly movable;

a drive casing rotatably disposed around the drive shaft; and

a conversion mechanism configured to convert a linear movement of the drive shaft into a rotational movement of the drive casing, wherein the conversion mechanism comprises a first spiral groove provided in an exterior surface of the drive shaft, a second spiral groove provided in an interior surface of the drive casing, and a plurality of balls interposed between the first spiral groove and the second spiral groove;

a sleeve fixed to an exterior surface of the drive casing, wherein the drive casing is connected to the swing door through the sleeve; and

a suppressor received in the sleeve and a spring configured to cause the suppressor to be biased downwardly, wherein the suppressor is configured to suppress an upward movement of the drive casing by a biasing force of the spring.

2 . The driving apparatus according to claim 1 , wherein:

the second spiral groove is recessed from the interior surface of the drive casing by a predetermined depth; and

the predetermined depth of the second spiral groove is less than a thickness of the drive casing.

3 . The driving apparatus according to claim 1 , wherein a radius of each ball is substantially the same as a cross-sectional radius of the first spiral groove and a cross-sectional radius of the second spiral groove.

4 . The driving apparatus according to claim 1 , wherein:

the conversion mechanism further comprises a ball retainer disposed between the drive shaft and the drive casing; and

the ball retainer comprises a plurality of through holes configured to receive the plurality of balls, respectively.

5 . The driving apparatus according to claim 4 , wherein:

the drive casing comprises an upper stopper and a lower stopper mounted therein; and

the upper stopper and the lower stopper are configured to restrict a movement of the ball retainer.

6 . The driving apparatus according to claim 1 , wherein:

the first spiral groove has a single-start spiral configuration or a multi-start spiral configuration; and

the second spiral groove has a single-start spiral configuration or a multi-start spiral configuration.

7 . The driving apparatus according to claim 1 , wherein:

the drive casing comprises an upper stopper and a lower stopper disposed therein; and

the upper stopper is disposed in an upper portion of the drive casing and the lower stopper is disposed in a lower portion of the drive casing.

8 . A driving apparatus for a swing door, the driving apparatus comprising:

a drive shaft that is linearly movable;

a linear actuator coupled to the drive shaft to cause the drive shaft to move linearly;

a drive casing rotatably disposed around the drive shaft; and

a conversion mechanism configured to convert a linear movement of the drive shaft into a rotational movement of the drive casing, wherein the conversion mechanism comprises a first spiral groove provided in an exterior surface of the drive shaft, a second spiral groove provided in an interior surface of the drive casing, and a plurality of balls interposed between the first spiral groove and the second spiral groove;

a sleeve fixed to an exterior surface of the drive casing, wherein the drive casing is connected to the swing door through the sleeve; and

a suppressor received in the sleeve and a spring configured to cause the suppressor to be biased downwardly, wherein the suppressor is configured to suppress an upward movement of the drive casing by a biasing force of the spring.

9 . The driving apparatus according to claim 8 , wherein the linear actuator comprises:

a cylinder tube having a first open end and a second open end opposing each other;

a piston movable in the cylinder tube;

a first end cover mounted in the first open end of the cylinder tube; and

a second end cover mounted in the second open end of the cylinder tube.

10 . The driving apparatus according to claim 9 , wherein:

the linear actuator further comprises an internal rod mounted at the center of the piston; and

the internal rod comprises a first extension portion extending from the piston toward the first end cover and a second extension portion extending from the piston toward the second end cover.

11 . The driving apparatus according to claim 8 , further comprising a lubricating bush and a packing provided between the drive shaft and the linear actuator, wherein the packing is located below the lubricating bush.

12 . The driving apparatus according to claim 11 , wherein:

the lubricating bush comprises a lubricating groove provided in an interior surface thereof; and

the lubricating groove is open to the exterior surface of the drive shaft.

13 . The driving apparatus according to claim 11 , wherein the lubricating bush comprises a brass material.

14 . The driving apparatus according to claim 11 , wherein the packing comprises:

an inner contact portion contacting the exterior surface of the drive shaft;

an outer contact portion contacting the linear actuator; and

a recessed portion provided between the inner contact portion and the outer contact portion.

15 . The driving apparatus according to claim 14 , wherein:

the inner contact portion comprises a plurality of inner lips having different inner diameters; and

the plurality of inner lips define a step structure.

16 . A vehicle comprising:

a vehicle body;

a swing door coupled to the vehicle body and configured to cover an aperture in the vehicle body;

a swing arm having a first end portion mounted on an interior surface of the swing door;

a driving apparatus, wherein a second end portion of the swing arm is connected to the driving apparatus, and wherein the driving apparatus comprises:

a drive shaft that is linearly movable;

a drive casing rotatably disposed around the drive shaft; and

a conversion mechanism configured to convert a linear movement of the drive shaft into a rotational movement of the drive casing, wherein the conversion mechanism comprises a first spiral groove provided in an exterior surface of the drive shaft, a second spiral groove provided in an interior surface of the drive casing, and a plurality of balls interposed between the first spiral groove and the second spiral groove;

a sleeve fixed to an exterior surface of the drive casing, wherein the drive casing is connected to the swing door through the sleeve; and

a suppressor received in the sleeve and a spring configured to cause the suppressor to be biased downwardly, wherein the suppressor is configured to suppress an upward movement of the drive casing by a biasing force of the spring.

17 . The vehicle according to claim 16 , wherein:

the second spiral groove is recessed from the interior surface of the drive casing by a predetermined depth; and

the predetermined depth of the second spiral groove is less than a thickness of the drive casing.

18 . The vehicle according to claim 16 , wherein a radius of each ball is substantially the same as a cross-sectional radius of the first spiral groove and a cross-sectional radius of the second spiral groove.

19 . The vehicle according to claim 16 , wherein:

the conversion mechanism further comprises a ball retainer disposed between the drive shaft and the drive casing;

the ball retainer comprises a plurality of through holes configured to receive the plurality of balls, respectively;

the drive casing comprises an upper stopper and a lower stopper mounted therein; and

the upper stopper and the lower stopper are configured to restrict a movement of the ball retainer.

20 . The vehicle according to claim 16 , wherein:

the driving apparatus further comprises a linear actuator coupled to the drive shaft to cause the drive shaft to move linearly; and

the linear actuator comprises a cylinder tube having a first open end and a second open end opposing each other, and a piston movable in the cylinder tube.