PURPOSE: To reduce a cover space by providing a cover composed of a pair of a fan-shaped side plate and a circular arc-shaped outer plate and rotatably, developably and reducibly forming the cover as an inner edge end part of the side plate part is made a supporting point.
CONSTITUTION: A cover 23 is a multi-stage collapsible type, divided into four parts of a first stage cover part 23a to a fourth stage cover part 23d, which are formed of fan-shaped small side plate parts 24a-24d and small outer plate parts 25a-25d between the outer edges thereof. In addition, the cover 23 is rotatably, developably and reduciably formed around the axis center of a fulcrum 27. At first, when the cover 23 is opened, the cover part 23a is rotated up to the side of a pit 44 by an electric motor. As a result. engagement of an engaged pawl provided on the outer plate parts 25a-25d is slipped, the cover parts 23b-23d are rotated by their dead load, the cover 23 is collapsed, housed in the pit 44 and a space of the cover 23 can be reduced. When the cover 23 is closed, the cover part 23a is rotated up to the side of a control part 8 with the electric motor. At this time, a locking pawl 29 of the cover part 23a is engaged with a pawl 30 to be locked of the cover part 23b, which is rotated. Successively, the cover parts 23c, 23d are rotated and the cover 23 can be stopped at a desired position or can be shut down wholly.
HAYASHI TOMOAKI
MIYOSHI KAZUHIKO
IWAOKA JUNZO
