To provide a water pump capable of preventing noise generation, a short lifetime, coming-off of a belt by making variation of a gap due to assembly of a ball bearing small and making an axial gap and an angular gap small.
In this water pump, the ball bearing 5 is put between a cylinder part 2a of an inner fixed member 2 formed by pressing steel plate and a cylinder part 3c of an outer rotating member formed by pressing steel plate, an inner ring 5a of the ball bearing 5 is press-fitted on an outer circumference of the cylinder part 2a of the fixed member 2, and an outer ring 5b is press-fitted in an inner circumference of the cylinder part 3c of the rotating member 3. A pulley part 3e on which a belt is wound around is formed on an outer side of the cylinder part 3 of the rotating member 3 as one body via an outside flange part 3d, thickness t1 of the cylinder part 3c is 0.5 times or more, and 0.93 times or less of thickness t of the outside flange part 3d.
Einosuke Kishimoto
Akira Watanabe
Kiyosue Yasuko
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