STRUCTURE OF WATER PUMP

PROBLEM TO BE SOLVED: To prevent the occurrence of a problem in which discharge of water from a drain is erroneously detected as water leakage caused by failure of a water pump, a problem in which slipping arises between a belt and a pulley caused by wetting of the belt and the pulley due to the water discharged from the drain, and a problem in which leakage of water from the drain in acceleration of a vehicle or on uphill is erroneously detected as water leakage due to the failure of the water pump.SOLUTION: A structure of a water pump includes a driving shaft 1 receiving transmission of power from a crank shaft of an internal combustion engine through a pump-side pulley 2, a housing 3 including a shaft hole 3a as a shaft supporting part rotatably supporting the driving shaft 1, a chain cover 4 as a pump chamber member forming a pump chamber 5 together with the housing 3, a seal part 7 disposed between the pump chamber 5 and the shaft hole 3a of the housing 3, a water reservoir part 8 formed between the housing 3 and the chain cover 4, and a drain 9 opened at a side opposite to the side of the pump-side pulley 2 from the chain cover 4, and discharging the water from the water reservoir part 8. 【課題】ドレンからの水の排出がウォータポンプの故障による水漏れと誤認される不具合や、ドレンから排出された水がベルトやプーリにかかることによりベルトとプーリとの間でスリップが発生する不具合や、車両の加減速や登坂時に水がドレンから漏れ出ることが、ウォータポンプの故障による水漏れと誤認される不具合の発生を抑制する。【解決手段】内燃機関のクランクシャフトからポンプ側プーリ２を介して動力の伝達を受ける駆動軸１と、この駆動軸１を回転自在に支持する軸支持部たる軸孔３ａを備えたハウジング３と、ハウジング３との間でポンプ室５を形成するポンプ室構成部材たるチェーンカバー４と、ポンプ室５とハウジング３の軸孔３ａとの間に設けられるシール部７と、ハウジング３とチェーンカバー４との間に形成される水溜部８と、チェーンカバー４からポンプ側プーリ２がある側と反対側に開口し水溜部８から水を排出するドレン９とを具備する。【選択図】図１