Patent ID: 8402992

Claim:
A branching unit for boring without stopping a passage of fluid suitable for boring a portion of a pipe wall of an existing pipe to form an opening in the pipe wall with a boring machine having a hole saw so as to connect a branch pipe to the existing pipe, the branching unit comprising: a sealing case including first and second separate cases separated from each other in a circumferential direction of the existing pipe and enclosing a portion of the existing pipe, wherein a branch pipe portion branching off of the existing pipe by protruding in a radial direction of the existing pipe is formed integral with the first separate case; a valve body including a portion having an arc-shaped lateral cross section for opening/closing a branch hole of the branch pipe portion by rotating in the circumferential direction of the existing pipe between an inner periphery surface of the sealing case and an outer periphery surface of the existing pipe; a valve seat provided on the inner periphery surface of the first separate case with which the valve body contacts in a valve-closed state; and a rotation mechanism for rotating the valve body, the rotation mechanism comprising: an operation portion rotated outside the sealing case; a driving gear unit which rotates by the rotation of the operation portion; and a driven gear provided on the valve body for rotating the valve body in the circumferential direction of the existing pipe following the rotation of the driving gear unit, wherein: a gear case portion is formed integral with an upper portion of the first or second separate case, the gear case portion having a lower opening which opens in a downward direction, allowing for a portion of the driving gear unit to mesh with the driven gear, and an upper opening which opens in an upward direction, wherein the gear case portion forms a depressed portion accommodating a portion of the driving gear unit, and allows the driving gear unit to be inserted and assembled through the upper opening; a cover which shuts the upper opening of the gear case portion is fastened to the gear case portion; the operation portion protrudes in the upward direction through a through hole vertically running through the cover; and the cover is removed from the gear case portion so as to allow the driving gear unit to be taken out from the gear case portion through the upper opening.