Housing assembly for use in fan unit and fan unit including the same

A housing assembly for use in a fan unit, the housing assembly comprising:

• an upper housing and a lower housing coaxially coupled to each other to define a substantially cylindrical space for accommodating a plurality of blades therein;
• wherein
• the upper housing has a lower end surface and a lower engaging portion adjacent thereto, and the lower housing has an upper end surface and an upper engaging portion adjacent thereto;
• the lower and upper engaging portions are arranged to engage each other to couple the upper and lower housings to each other by rotating one of the upper and lower housings about a center axis of the upper and lower housings relative to the other in a first direction with the lower end surface of the upper housing in axial contact with the upper end surface of the lower housing;
• and
• when the lower and upper engaging portions are in engagement, one of the lower and upper engaging portions presses the other lower and upper engaging portion in two axial directions to cause elastic axial deformation of the other lower and upper engaging portion, and one of the lower and upper engaging portions presses the other lower and upper engaging portion in both the first direction and a second direction opposite thereto to cause elastic circumferential deformation of the other lower and upper engaging portion.