Pump apparatus

A pump apparatus that is installed in a cooling system of an internal combustion engine which circulates cooling water of the internal combustion engine and which cools the cooling water according to temperature of the cooling water, the pump apparatus comprising:

• a first housing member having a generally circular recess portion;
• a pump rotor that is placed within the recess portion and that is rotatably supported by the first housing member;
• and
• a second housing member that is fixed to an opening end side of the recess portion of the first housing member so as to define, together with the first housing member, a pump operation chamber that corresponds to the recess portion,
• wherein the first housing member includes a housing body portion in which the recess portion is formed, and a discharge-side cylindrical portion that is formed integrally with the housing body portion so as to define a discharge passageway of the cooling water from the pump operation chamber, wherein an outer peripheral portion of the housing body portion has a bolt hole configured to fasten and fix the pump apparatus to the internal combustion engine;
• and
• wherein the second housing member includes a cover portion that covers the opening end side of the recess portion, and a suction-side cylindrical portion that is formed integrally with the cover portion so as to define a suction passageway of the cooling water,
• wherein the cooling system includes a thermostat that is capable of restricting amount of flow of the cooling water sucked from an upstream side to a pump operation chamber side, at an intermediate position in the suction passageway, and the thermostat is supported by the suction-side cylindrical portion of the second housing member so as to be positioned at an intermediate position in the suction passageway.