Variable pitch marine propeller

Details Variable pitch marine propeller Variable pitch marine propeller

1999-10-14

2001-08-21

Look, Edward K. (Department: 3745)

Fluid reaction surfaces (i.e., impellers)

Having positive means for impeller adjustment

Power or manual actuator on non-rotatable part

C416S166000, C440S050000

Reexamination Certificate

active

06276898

ABSTRACT:

BACKGROUND
The present invention relates to propeller propulsion devices, and more particularly to variable pitch propeller devices for marine craft such as inboard and outboard pleasure boats, yachts and fishing boats.
Variable pitch aircraft propellers are well known, implementations including hydraulic actuators being disclosed, for example, in U.S. Pat. Nos. 2,425,261 to Murphy et al., 2,554,611 to Biermann, and 4,362,467 to the present inventor. The '467 patent, which is incorporated herein by this reference, discloses a mounting flange for mounting to the propeller shaft flange of an engine, a hub for pivotally supporting a plurality of blades on respective radial axes, and a stationary annular hydraulic cylinder and piston between the mounting flange and the hub, the piston being connected by a yoke and transverse pin to a longitudinal rack member that engages respective pinions of the blades to rotate same through a wide angle of approximately 90°.
Typical marine propeller installations include a rearwardly extending propeller shaft on which is mounted a one-piece propeller having an annular hub portion, the shaft extending through the hub and threadingly engaging a retainer nut. The hub is secured against rotation relative to the shaft such as by splined engagement or by one or more keys or shear pins.
The aircraft propeller implementation of the '467 patent, while having certain advantages including the stationary annular hydraulic cylinder, is unsuitable for use in typical marine applications for a number of reasons. For example:
1. The shaft interferes with placement and movement of the yoke pin and the rack member;
2. The rear of the hub, including a biasing spring mechanism therein, interferes with access to the nut whereby the hub would be secured to the shaft;
3. The hub and blades would be difficult to remove for servicing and/or replacement in case of damage by underwater hazards; and
4. The device would be subject to water damage in that hub is unsealed, and the piston seals would have to operate in a wet environment.
A further problem exhibited in the prior art relates to the need in marine applications for means to decouple the propeller in case of impact with potentially damaging foreign objects such as submerged rocks and logs. Typically, such a device couples the propeller to it's shaft by a “shear pin” that transmits normal driving torques but which is supposed to sever when the propeller strikes an obstacle. The shear pins of the prior art are difficult to replace in that the propeller must be removed from the shaft, typically with significant difficulty resulting from interference with jagged edges of the severed shear pin. Moreover, the difficulty with which the propeller is removed significantly increases the risk of it's being dropped into the water.
Thus there is a need for a variable pitch marine propeller that is effective for providing a wide angular range, that is compatible with existing fixed-pitch installations, that is easy to service, repair, and replace, and is resistant to water damage.
SUMMARY
The present invention meets this need by providing a modular variable pitch system configuration of propeller and stationary annular actuator for facilitating assembly, servicing and replacement particularly of parts most subject to damage by under-water hazards. The system is adapted for marine drives including a driven shaft having a locating surface, a torque-transmitting surface, and a retainer surface for engagement by a retaining device, the shaft extending from a base structure such as a drive housing. In one aspect of the invention, a propeller system having an easily serviceable torque limiting safety device includes a propeller unit having a hub rotatably mountable on the driven shaft for supporting a plurality of radially projecting blade members, a hub passage being formed in structure rigidly fixed relative to the hub; a sleeve member mountable on the driven shaft in engagement with the torque-transmitting surface and having a sleeve passage formed in one wall thereof, the sleeve passage being alignable with the hub passage for placement of a shear pin in engagement with the hub and sleeve passages; and a retainer member removably mountable in covering relation to at least one of the hub and sleeve passages when the shear pin is placed therein for retaining the shear pin, whereby torque is transmittable from the sleeve member through the shear pin to the hub until fracture of the shear pin in response to occurrence of a predetermined limiting torque, allowing the hub to rotate relative to the driven shaft, and when the retainer member is removed from covering the at least one of the hub and sleeve passages, the shear pin is removable from the passages for replacement without the hub being removed from the driven shaft. The system can be assembled with the shear pin located in engagement with the hub and sleeve passages, the retainer member being removably fastened in fixed relation to the hub.
Preferably the blade members are movably supported relative to the hub, a yoke member being axially movable relative to the hub in response to a power actuator, and means for moving the blade members in variable pitch relation to the hub in response to axial movement of the yoke member. The means for moving can include each blade member being rotatably mounted on a respective radially extending axis of the hub and having a pinion fixedly connected thereto, and the propeller yoke including axially extending rack elements engaging corresponding ones of the pinions.
The power actuator can include an annular hydraulic cylinder rotatably supportable relative to the spindle and having a fluid port and means for preventing rotation of the cylinder by mechanical coupling to the base structure, an actuator piston sealingly axially movable in the hydraulic cylinder for coupling fluid flow relative to the port, a thrust bearing for transmitting axial force between the actuator piston and the yoke member, whereby the yoke member moves axially relative to the spindle in response to fluid flow into the port, and the spindle, the hub, and the yoke member can be rotated by the shaft while the cylinder and the piston are being prevented from rotation by the coupling to the base.
The shaft is operable submerged in water, and the system can further include power unit seal means for excluding water from the actuator piston and the thrust bearing. Preferably the propeller unit is separable from the drive shaft without disturbing the power actuator.
The yoke member can be a propeller yoke and the power actuator can be in a power unit, the power unit further including a spindle for coupling to the shaft and rotation therewith, a piston yoke for contacting the propeller yoke, a first thrust bearing for transmitting axial force between the spindle and the cylinder, and a second thrust bearing for transmitting axial force between the piston and the piston yoke. The piston yoke moves axially relative to the spindle in response to fluid flow into the port, and the spindle and the piston yoke can be rotated by the shaft while the cylinder and the piston are being prevented from rotation by the coupling to the base. The power unit is locatable adjacent the propeller unit opposite the retainer device whereby the axial force is transmitted from the locating surface, through the power unit to the propeller yoke by the piston yoke, and through the means for moving and the hub to the retainer device. The axial movement of the propeller yoke causes the blade members to move from a first position toward a second position relative to the hub in response to the fluid flow into the port.
Preferably the spindle is adapted for being clamped between the locating surface and the hub by the retainer device. Preferably the system further includes an antifriction radial bearing for concentrically supporting the cylinder relative to the spindle.
The system can further include a hydraulic control unit being fluid-connectable to the fluid port and including a primary hydr

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