Patent ID: 8571437

Claim:
A cooling device, comprising: a heat receiving unit disposed to contact a surface of a temperature-increasing part a temperature of which increases during an image forming process; a radiation unit transferring heat from a cooling liquid; a tube for circulating the cooling liquid between the heat receiving unit and the radiation unit in a liquid circulation direction; a conveying unit conveying the cooling liquid through the tube a coupling having an internal flow path and including a first end to which a first part of the tube is connected and a second end to which a second part of the tube is connected; and an outlet for draining the cooling liquid from the tube, wherein at least one of the first part of the tube and the second part of the tube extends to a position lower than a position of the coupling, when the first end of the coupling is an upstream end in the liquid circulation direction and the second end of the coupling is a downstream end in the liquid circulation direction, the first part of the tube connected to the first end of the coupling includes a first horizontal flow path located at a position lower than the position of the coupling and extending in a substantially horizontal direction, a first vertical flow path extending substantially vertically upward from a downstream end in the liquid circulation direction of the first horizontal flow path, and a second horizontal flow path extending in a substantially horizontal direction from a downstream end in the liquid circulation direction of the first vertical flow path and connected to the first end of the coupling; and the second part of the tube connected to the second end of the coupling includes a third horizontal flow path connected to the second end of the coupling and extending in a substantially horizontal direction; a second vertical flow path extending substantially vertically downward from a downstream end in the liquid circulation direction of the third horizontal flow path, and a fourth horizontal flow path extending in a substantially horizontal direction from a downstream end in the liquid circulation direction of the second vertical flow path and located at a position lower than the position of the coupling.