Extending and retracting device for vehicle step

1. An extending and retracting device for a vehicle step comprising:

a mounting bracket adapted to be fixed to a body of a vehicle;

a step bracket;

an arc sliding member made in the form of an arc sliding block and defining a pair of ends thereof, an intermediate portion of said arc sliding member fixed in said step bracket;

a driving arm defining a pair of ends thereof pivotally connected to respective said mounting bracket and step bracket; and

a supporting arm defining an upper end portion pivotally connected to said mounting bracket, and a lower end portion, said lower end portion formed with a substantially U-shaped groove defining a pair of side walls thereof, a portion of said step bracket located in said groove, a pair of arc slots are formed in respective said pair of side walls of said groove, said pair of ends of said arc sliding member extending substantially transversely into respective said pair of arc slots; and

wherein said arc sliding member is adapted to fit into said pair of arc slots so as to be slidable in said arc slots such that said lower end portion of said supporting arm is slidably connected to said step bracket.

2. An extending and retracting device for a vehicle step as set forth in claim 1 , wherein said arc sliding member is made in the form of a plurality of columnar bodies arranged in an arc array and defines a pair of ends thereof, said lower end portion of said supporting arm is formed with a substantially U-shaped groove defining a pair of side walls thereof, a portion of said step bracket is located in said groove, a pair of arc slots are formed in respective said pair of side walls of said groove, an intermediate portion of said arc sliding member is fixed in said step bracket, and said pair of ends of said arc sliding member are extended substantially transversely into respective said pair of arc slots.

3. An extending and retracting device for a vehicle step, comprising:

a mounting bracket adapted to be fixed to a body of a vehicle;

a step bracket that is formed with at least one arc slot;

a driving arm defining a pair of ends thereof pivotally connected to respective said mounting bracket and step bracket;

a supporting arm defining an upper end portion and a lower end portion, said upper end portion being pivotally connected to said mounting bracket; and

an arc sliding member that is fixed to said lower end portion of said supporting arm and adapted to fit into said arc slot so as to be slidable in said arc slot such that said lower end portion of said supporting arm is slidably connected to said step bracket.

4. An extending and retracting device for a vehicle step as set forth in claim 3 , wherein said arc sliding member is made in the form of an arc sliding block and defines a pair of ends, said step bracket is formed with a substantially U-shaped groove defining a pair of side walls of said groove, said lower end portion of said supporting arm is located in said groove, a pair of arc slots are formed in respective said side walls of said groove, an intermediate portion of said arc sliding member is fixed in said step bracket, and said pair of ends of said arc sliding member are extended substantially transversely into respective said pair of arc slots.

5. An extending and retracting device for a vehicle step as set forth in claim 3 , wherein said arc sliding member is made in the form of a plurality of columnar bodies arranged in an arc array and defines a pair of ends thereof, said step bracket is formed with a substantially U-shaped groove defining a pair of side walls of said groove, said lower end portion of said supporting arm is located in said groove, a pair of arc slots are formed in respective said side walls of said groove, an intermediate portion of said arc sliding member is fixed in said step bracket, and said pair of ends of said arc sliding member are extended substantially transversely into respective said pair of arc slots.

6. An extending and retracting device for a vehicle step as set forth in claim 3 , wherein said arc sliding member is made in the form of an arc sliding block and defines a pair of ends thereof, said lower end portion of said supporting arm is formed with a substantially U-shaped groove defining a pair of side walls of said groove, a portion of said step bracket is located in said groove, and said pair of ends of said arc sliding member are fixed in respective said pair of side walls of said groove such that said arc sliding member passes through and is slidably fitted into said arc slot.

7. An extending and retracting device for a vehicle step as set forth in claim 3 , wherein said arc sliding member is made in the form of a plurality of columnar bodies arranged in an arc array and defines a pair of ends thereof, said lower end portion of said supporting arm is formed with a substantially U-shaped groove defining a pair of side walls of said groove, a portion of said step bracket is located in said groove, and said pair of ends of said arc sliding member are fixed in respective said pair of side walls of said groove such that said arc sliding member passes through and is slidably fitted into said arc slot.

8. An extending and retracting device for a vehicle step as set forth in claim 3 , wherein said step bracket includes a body portion and an extension portion formed with a step groove therein for fixing the vehicle step to said step bracket, said arc sliding member is located in said arc slot substantially at an upper end of said arc slot when said device is in an extended position, and said arc sliding member is located in said arc slot substantially at a lower end of said arc slot when said device is in a retracted position.

9. An extending and retracting device for a vehicle step as set forth in claim 3 , wherein said arc slot defines a pair of ends and a curvature radius at said pair of ends of said arc slot is smaller than that at an intermediate portion of said arc slot.

10. An extending and retracting device for a vehicle step as set forth in claim 3 , wherein said arc slot defines a center of curvature and said arc slot and center of curvature are located to the same side of an imaginary line connecting with each other a pair of pivot points defined by respective said pair of ends of said driving arm.

11. An extending and retracting device for a vehicle step as set forth in claim 3 , wherein said step bracket includes a body portion and an extension portion formed with a step groove therein for fixing the vehicle step to said step bracket, said body portion is made in the form of a columnar structure defining a substantial center of curvature thereof, and said arc slot defines a center of curvature substantially coinciding with said center of curvature of said columnar structure.