Cooling device for additive injection valve

A cooling device configured to cool, using a coolant, an injection valve that injects an additive, the cooling device comprising:

• a first port into which the coolant flows;
• a first passage connected to the first port and extending to an outer periphery of a tip portion of the injection valve;
• a second port provided above the first port, through which the coolant flows out;
• a second passage connected to the first passage and extending along the injection valve from the outer periphery of the tip portion and connected to the second port;
• and
• a movable member configured to move in response to a flow of the coolant within a height between the first port and the second port to communicate the first passage and the second passage with each other when a flow rate of the coolant is lower than a predetermined flow rate and to disconnect the first passage and the second passage from each other when the flow rate of the coolant is higher than the predetermined flow rate.