Pipe unit coupling structure

A pipe unit coupling structure comprising:

• a first member in which a first hole that is opened to a lower side is formed;
• a second member including a pipe unit which is coupled to the first member by being inserted into the first hole;
• and
• a third member coupled to the second member by a coupling unit, wherein
• the second member has an inclined surface formed on an upper end surface of a tip of the pipe unit on an insertion side and positioned on a plane inclined with respect to a horizontal plane,
• the coupling unit is positioned at a lower side of the pipe unit, and is configured such that a direction of separation is in a horizontal direction, and
• the inclined surface is configured in such a manner that, when the inclined surface is pressed against the first member from an upper side when the pipe unit of the second member is inserted into the first hole of the first member from the lower side by the first member being assembled in a downward direction with respect to the pipe unit of the second member in a state where the second member and the third member are coupled to each other, a force is applied from the second member to the third member at the coupling unit, in a direction opposite to a direction of separation of the second member, by a component force in the horizontal direction, of a load applied from the first member to the inclined surface.