A sliding door opening and closing device that horizontally opens and closes the sliding door with application of light weight is provided. A load-type door opening and closing device includes: a sliding support rail slidably supporting the door to open and close the door; a door opening rail provided in the door and inclined upward in an opening direction of the door; a sliding member sliding on the door opening rail; a footboard; and a coupling member that couples the sliding member with the footboard. The sliding member is located at an upper end side of the door opening rail when the door is closed, and is depressed against the door opening rail by stepping force acting on the footboard during opening operation, to displace the door in the opening direction.

A sliding door opening and closing device that horizontally opens and closes the sliding door with application of light weight is provided. A load-type door opening and closing device includes: a sliding support rail slidably supporting the door to open and close the door; a door opening rail provided in the door and inclined upward in an opening direction of the door; a sliding member sliding on the door opening rail; a footboard; and a coupling member that couples the sliding member with the footboard. The sliding member is located at an upper end side of the door opening rail when the door is closed, and is depressed against the door opening rail by stepping force acting on the footboard during opening operation, to displace the door in the opening direction.

An automatic door opening and closing device include a housing which may contain a control unit. A motor may be in electronic communication with the control unit, and a wheel may be coupled to the motor so that the motor may be operable to rotate the wheel in a clockwise direction and in a counter clockwise direction. A chassis may be configured to couple the motor to a door so that the wheel is in contact with a ground surface below the door. The motor may be operable to rotate the wheel clockwise across the ground surface to motivate the door in a first direction, and the motor may be operable to rotate the wheel counterclockwise across the ground surface to motivate the door in a second direction. By motivating the door in either the first direction or the second direction, the device may be configured to move the door into, out of, and between the open and closed positions.

A sliding door opening and closing device that horizontally opens and closes the sliding door with application of light weight is provided. A load-type door opening and closing device includes: a sliding support rail slidably supporting the door to open and close the door; a door opening rail provided in the door and inclined upward in an opening direction of the door; a sliding member sliding on the door opening rail; a footboard; and a coupling member that couples the sliding member with the footboard. The sliding member is located at an upper end side of the door opening rail when the door is closed, and is depressed against the door opening rail by stepping force acting on the footboard during opening operation, to displace the door in the opening direction.

A sliding door opening and closing device that horizontally opens and closes the sliding door with application of light weight is provided. A load-type door opening and closing device includes: a sliding support rail slidably supporting the door to open and close the door; a door opening rail provided in the door and inclined upward in an opening direction of the door; a sliding member sliding on the door opening rail; a footboard; and a coupling member that couples the sliding member with the footboard. The sliding member is located at an upper end side of the door opening rail when the door is closed, and is depressed against the door opening rail by stepping force acting on the footboard during opening operation, to displace the door in the opening direction.