US 5,368,442 AGranted

Automatic variable discrete pitch marine propeller

AssigneeNautical Development, Inc.

InventorStephen R. Speer

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Abstract

A self-actuating variable pitch marine propeller which incorporates two or more blades which are rotatably connected to a central hub; the blades rotate relative to the hub center about the shank axis. In operation, the blades are biassed towards the lower pitch, both by mechanical means, such as a spring, and optionally also by hydrodynamic load means. As the propeller rotational speed increases, centrifugal forces act to move the blades towards the higher pitch position. In one alternative mode the hydrodynamic load also acts towards the higher pitch position. There is further provided a holding mechanism to retain or hold the blades at least preferably in the lower pitch position, the holding mechanism being so designed that at a sharply defined combination of parameters, including rotational speed and optimally hydrodynamic load acting on the blades, the holding mechanism is caused to be released and the blades permitted to move to a second higher pitch position.

Claims15

Dependent claims

A self-actuating variable pitch marine propeller comprising a hub case, drive securing means designed to secure the propeller to a rotating drive shaft on a boat propulsion system such that the propeller rotates with the drive shaft;

a plurality of blades extending radially outward from the hub case, each blade comprising a hydrodynamic surface, and a blade shaft extending from the hydrodynamic surface and having a blade shaft axis extending transverse to the drive shaft axis, the center of pressure of the hydrodynamic surface being located forward of the blade shaft axis so as to generate a hydrodynamic torque on the blade tending to turn the blade, towards a higher pitch, about the blade axis when the propeller is rotated, said blade shaft being pivotally connected to the hub case, about the blade shaft axis, such that rotation of the propeller by the drive shaft generates a centrifugal reaction force tending to cause each blade to pivot about the blade axis;
mechanical blade holding means mounted to the hub case, and which tends to hold the blade in one extreme pitch position until the rotational movement of the propeller generates sufficient centrifugal force effect to overcome such mechanical hold;
whereby the blades are automatically movable between a first lower angle of pitch operational position, and a second higher angle of pitch operational position, as the rotational speed of the propeller increases.

a plurality of blades extending radially outward from the hub case, each blade comprising a hydrodynamic surface and a blade shaft extending from the hydrodynamic surface along a blade axis extending transverse to the drive shaft axis, the center of pressure of the hydrodynamic surface being distant from the blade axis so as to generate a hydrodynamic torque about the blade axis when the propeller is rotated, said blade shaft being pivotally, about the blade axis, slidably connected to the hub case, such that rotation of the propeller by the drive shaft generates a centrifugal reaction force tending to cause the blades to pivot about the blade axis;
motion direction means, comprising a cam surface and a cam follower, operatively connected between the hub case and a blade shaft, the cam surface having at least two portions, a first portion designed to cause such blade to move pivotally about the blade axis, and a second portion designed to prevent pivoting movement when the blade is in a first operational pitch position;
whereby the second portion resists the hydrodynamic force torque generated by the blade surface, and thus tends to hold the blade in the first operational pitch position until the rotational movement of the propeller generates sufficient centrifugal force effect to cause the cam follower to move to the second portion of the cam surface, and thus to permit pivotal movement of the blade towards the second pitch position.

Dependencies are inferred from the claim text.

Facts

Application: 08/152,966Filed 15 Nov 1993 · continuation
Priority: 17 Jul 1988
Granted: 29 Nov 1994
Term ends: Not estimatedThe source records don’t support an estimate.

Classification3 codes

B63H 3/008
Propeller-blade pitch changing: characterised by self-adjusting pitch, e.g. by means of springs, centrifugal forces, hydrodynamic forces
B63H 3/04
Actuated by control element coaxial with propeller shaft, e.g. the control element being rotary: the control element being reciprocatable
B63H
Marine propulsion or steering

Family

Serial216,014Parent of this division · filed 17 Jul 1988
Serial376,112Parent of this continuation-in-part · filed 6 Jul 1989
Serial645,096Parent of this division · filed 24 Jan 1991
Serial912,153Parent of this continuation · filed 10 Jul 1992
US 5,129,785 AParent of this division
US 5,032,057 AParent of this continuation-in-part
US 4,929,153 AParent of this division
US 5,368,442 AThis patent

From the US filing history. Foreign family members aren’t listed.

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