PROPULSION UNIT OF SMALL SHIP

To provide a propulsion unit of a small ship using a cylinder having a piston reciprocating in a tube push out water backward in both the forward motion and the backward motion.SOLUTION: A propulsion unit is composed by providing a front chamber side input unit 731 and a front chamber side output unit in a front chamber 73 of a cylinder 7, and a rear chamber side input unit 741 and a rear chamber side output unit in a rear chamber 74. The front chamber side input unit 731 has a check valve 732 for front chamber side input which is opened in water, closes when a piston 72 moves forward, and opens when the piston moves backward. The front chamber side output unit has a check valve for front chamber side output which opens toward a rear side of a hull, closes when the piston moves backward, and opens when the piston moves forward. The rear chamber side input unit 741 has a check valve 732 for rear chamber side input which is opened in water, opens when the piston moves forward, and closes when the piston moves backward. The rear chamber side output unit has a check valve for front chamber side output which opens toward the rear side of the hull, closes when the piston moves backward, and opens when the piston moves forward.SELECTED DRAWING: Figure 9 【課題】チューブ内を往復するピストンが往動及び復動いずれでも水を後方に押し出すシリンダを利用した小型船舶の推進ユニットを提供する。【解決手段】シリンダ７の前室73に前室側入力部731及び前室側出力部を、後室74に後室側入力部741及び後室側出力部を設けて構成され、前室側入力部731は、水中に開口し、ピストン72が前進する際に閉じ、後退する際に開く前室側入力用逆止弁732を有し、前室側出力部は、船体の後方に向けて開口し、ピストンが後退する際に閉じ、前進する際に開く前室側出力用逆止弁を有し、後室側入力部741は、水中に開口し、ピストンが前進する際に開き、後退する際に閉じる後室側入力用逆止弁732を有し、そして後室側出力部は、船体の後方に向けて開口し、ピストンが後退する際に閉じ、前進する際に開く前室側出力用逆止弁を有する。【選択図】図９