US 7,247,068 B2Granted

Boat propulsion unit

AssigneeHonda Motor Co., Ltd.

InventorsHiroshi Iwakami, Atsushi Kusuda, Masahiko Tsuchiya

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Abstract

A propulsion unit for a boat has a cooling water intake structure through which entry of cooling water is obstructed when the boat is towed while the impeller is not turned, and through which sufficient cooling water enters when the impeller is turned. The propulsion unit includes an impeller, plural stationary blades provided on the downstream side of the impeller, and a cooling water intake structure. The intake structure is disposed between adjacent first and second stationary blades, on the side of the first stationary blade relative to a bisecting line between the two stationary blades. Hydraulic pressure on the side of the first stationary blade, relative to the bisecting line, is lowered by guide action of the impeller, and hydraulic pressure on the side of the second stationary blade relative to the bisecting line is raised, respectively, when the boat is towed while the impeller is stopped.

Claims10

Dependent claims

A propulsion unit for a boat, the propulsion unit comprising

a cylindrical pump housing,
a rotatable impeller disposed in the cylindrical pump housing, said impeller having an upstream side and a downstream side,
a plurality of stationary blades disposed within the pump housing on the downstream side of the impeller, wherein the stationary blades are provided for guiding a fluid stream in an axial direction of the pump housing,
an intake structure for extracting cooling water from the pump housing and sending the cooling water to an engine, a water muffler and other water-cooled members, the intake structure disposed between a first stationary blade and a second stationary blade which is adjacent to the first stationary blade, wherein:
a bisecting line bisects the space between the first stationary blade and the second stationary blade,
the intake structure is provided on a part of the pump housing on a side of the first stationary blade relative to the bisecting line, and
wherein the propulsion unit is constructed and arranged such that when the boat is towed while the impeller is stopped, hydraulic pressure on the side of the first stationary blade relative to the bisecting line is lowered by the guide action of the impeller, and hydraulic pressure on a side of the second stationary blade relative to the bisecting line is raised, respectively.

4 more elements

A propulsion unit for a boat, the propulsion unit comprising

a cylindrical pump housing,
a rotatable impeller disposed in the cylindrical pump housing, and
a plurality of stationary blades disposed on the downstream side of the impeller for guiding a fluid stream in an axial direction of the pump housing,
an intake structure for extracting cooling water from the cylindrical pump housing, the cooling water sent from the intake structure to an engine, a water muffler and other water-cooled members, the intake structure disposed between a first stationary blade and a second stationary blade, the first stationary blade disposed adjacent to the second stationary blade, wherein
a bisecting line bisects the space between the first stationary blade and the second stationary blade,
the intake structure is provided between the first stationary blade and the second stationary blade such that the intake structure is displaced toward a side of the first stationary blade relative to the bisecting line, and
when the boat is towed while the impeller is stopped, hydraulic pressure on the side of the first stationary blade relative to the bisecting line is lowered by the guide action of the impeller, and hydraulic pressure on a side of the second stationary blade relative to the bisecting line is raised, respectively.

4 more elements

Dependencies are inferred from the claim text.