Marine propulsion – Screw propeller – Propeller arrangement
Reexamination Certificate
1999-10-04
2001-04-24
Morano, S. Joseph (Department: 3617)
Marine propulsion
Screw propeller
Propeller arrangement
C440S072000, C440S079000, C114S020100, C114S338000, C416S128000
Reexamination Certificate
active
06220906
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The invention relates to marine propulsion systems including drive shafts and propellers, and is directed more particularly to a marine propulsion system in which there is only a single drive shaft and two counter rotatable propellers.
(2) Description of the Prior Art
The use of counter-rotating propellers in marine propulsion systems is known. In particular, and referring to
FIG. 1
, such arrangements of propellers
10
,
12
have found utility in torpedoes and unmanned undersea vehicles
14
, and are favored in view of their efficiency, quiet operation, and the fact that they are torque balanced.
Known systems, as shown in
FIG. 2
, include two propeller drive shafts
16
,
18
, one for each propeller. Inasmuch as the two propellers
10
,
12
typically are in axial alignment with each other, one of the drive shafts
18
is nested inside the other
16
. A drive source
20
, such as a motor or engine, drives the two shafts
16
,
18
. Bearings
22
are required between the two shafts, as well as between the outer shaft
16
and the vehicle body, or other support structure
24
. Seals (not shown) are also required between the two shafts.
When an electric motor is used for the drive source
20
, the use of two counter-rotating shafts requires a relatively complex motor, typically requiring a hole through the motor in which the inner shaft is disposed, or a secondary outer case which allows the field to rotate as well as the outer shaft.
There is a need for a simpler structure with respect to the drive shaft component of the assembly and a structure which permits use of an ordinary electric motor.
SUMMARY OF THE INVENTION
An object of the invention is to provide a marine propulsion assembly wherein two propellers rotate in opposite directions and are driven by a single drive shaft.
With the above and other objects in view, as will hereinafter appear, a feature of the present invention is the provision of a marine propulsion assembly which includes a drive shaft, a first propeller fixed to the drive shaft and turnable therewith in a first direction, and an annular array of gear teeth disposed on the first propeller and turnable therewith. The assembly further includes a second propeller aligned with the first propeller, and an annular array of gear teeth disposed on the second propeller. Bevel gears are disposed between the first and second propellers and are each provided with a single array of teeth engaged with the first and second annular arrays of gear teeth. The bevel gears transmit rotation of the drive shaft and the first propeller to the second propeller, such that the second propeller turns in an opposite direction relative to the first propeller.
The above and other features of the invention, including various novel details of construction and combinations of parts, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular devices embodying the invention are shown by way of illustration only and not as limitations of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention.
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patent: D. 325916 (1992-05-01), Lanier
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patent: 3087553 (1963-04-01), Kostyun
patent: 5389020 (1995-02-01), Clark
patent: 421255 (1911-02-01), None
patent: 433998 (1998-09-01), None
patent: 6194 (1984-01-01), None
patent: 92296 (1984-05-01), None
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patent: 98/38085 (1998-09-01), None
Kasischke James M.
Lall Prithvi C.
McGowan Michael J.
Morano S. Joseph
The United States of America as represented by the Secretary of
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