US3639077A

US3639077A - Belt-driven pi-pitch cycloidal propeller

Info

Publication number: US3639077A
Application number: US57739A
Authority: US
Inventors: Elmer F Slates
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1970-07-23
Filing date: 1970-07-23
Publication date: 1972-02-01
Anticipated expiration: 1989-02-01

Abstract

A cycloidal propelling device for use on submersibles which operates in a flooded sea water environment and thereby eliminates the need for a protective sealing housing containing oil. While the propeller blades of the device are being driven in an orbital path, if a change in blade pitch is desired, a control shaft is rotated. Rotation of the blade pitch control shaft rotates a central pinion gear which drives a timing belt. Movement of the timing belt simultaneously and in synchronization rotates propeller blade gears and changes the pitch of the propeller blades which are mounted thereon with water-lubricated plastic bearings. Plug-in, pullout type plastic breakway propeller blades are used for easy repair and replacement.

Description

United States Patent Slates 1 Feb. 1, 1972 Elmer F. Slates, Ridgecrast, Calif.

(73] Assignee: The United States of America as represented by the Secretary of the Navy [22] Filed. July 23,1970

[21] AppI.No.: 57,739

[72] Inventor:

[52] U.S.Cl ..4l6/ll1,416/2,4l6/l74,

416/241 [51] lnt.Cl B631! 1/10 [58] Field ofSearch ..416/2,110,111,99,174, 224.

[56] References Cited UNITED STATES PATENTS 3,515.449 6/1970 Harbage ..4l6/l74 UX 3,302,988 2/1967 Senter..... 3,233,678 2/1966 Wilk ..416/241 FOREIGN PATENTS OR APPLlCATlONS 915,892 8/1946 France ..416/111 Primary Examiner-Everette A. Powell, Jr. Attorney-R. S. Sciascia and Thomas 0. Watson. Jr.

{57] ABSTRACT A cycloidal propelling device for use on submersibles which operates in a flooded sea water environment and thereby eliminates the need for a protective sealing housing containing oil. While the propeller blades of the device are being driven in an orbital path, if a change in blade pitch is desired. a control shaft is rotated. Rotation of the blade pitch control shaft rotates a central pinion gear which drives a timing belt. Movement of the timing belt simultaneously and in synchronization rotates propeller blade gears and changes the pitch of the propeller blades which are mounted thereon with wateriubricated plastic bearings. Plug-in, pullout type plastic breakway propeller blades are used for easy repair and replacement.

6 Claims, 1 Drawing Figure PATENTED FEB 1 I972 INVENTOR.

ELMER E SLATEZS VA... 0. ma}...

ATTORNEY BELT-DRIVEN Pl-PITCH CYCLOIDAL PROPELLER STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION The present invention relates generally to improvements in propelling apparatus, and more particularly it pertains to new and improved cycloidal propellers and driving means therefor.

The cycloidal propeller derives its name from the combined orbital motion of the propeller blades and the straight line motion of the vessel. The blades project from a rotating disc into the flow and orbit about an axis normal to the hull surface. The angle of attack of the blades is varied in a programmed manner to produce a resultant force in any direction normal to the axis of rotation.

The pitch ratio is defined as the ratio of the propeller advance per revolution (at zero slip) to the blade orbit radius, i.e., P=A/R, In the present invention, A=R by virtue of a simple belt and sun gear system and in this manner a fixed pi-pitch propeller with the steering center (P) located at R is obtained. (To obtain cycloidal blade motion, kinematics requires that the perpendicular to the profile cord of each blade pass through the same point, called the steering center).

Pi-pitch cycloidal propellers were used in the present invention because: (I of their high theoretical efficiency, and good efficiency over a broad speed range, (2) a cycloidal propeller can provide a 360 directional control through simple blade angle changes and does not require reversing gears or motors (two cycloidal propellers can control a vehicle in azimuth, updown, sideways and fore and aft directions, while it would take a minimum of three reversing-less efficient-motors and screw propellers to accomplish this), (3) cycloidal propellers have stabilizing characteristics, (4) the cycloidal propeller blades are essentially noiseless as compared to screw propellers, (5) they are readily water flooded, lubricated and pressure compensated for unlimited depth applications, and (6) the friction losses of a well-designed pi'pitch cycloidal propeller are quite small as they are mechanically more efficient.

In the field of cycloidal propellers, it has been the general practice to operate prior art propellers with an environmental protected planetary gear system and a speed-reducing gear box. To accomplish this a pressure-compensated sealed housing unit containing oil has been used. Such devices have been unsatisfactory in that the requirement of a pressure-compen' sated sealed housing to prevent destruction by the sea water environment is costly. Moreover, expensive gears with high tolerances to provide accurate meshing of the gears has been necessary. Also, the use of such intermeshing gears at times produces much noise when quiet operation is critical, as in some military uses. In addition, the propeller blades often become damaged and it has been difficult to repair or replace such blades.

OBJECTS OF THE INVENTION Accordingly, it is the object of the present invention to provide a more efficient, reliable, and less costly operation.

Another object is to provide a device which eliminates many moving parts and gears, is simple in construction, and is easy to manufacture.

A further object of the invention is the provision ofa timing belt which allows the device to operate in a flooded sea water and sandy environment and thereby eliminates the need for a protective sealed housing with oil heretofore required.

Still another object is to provide a srnooth-running and noiseless (noncavitating) operation due to the use of a timing belt and water-lubricated plastic hearing at every moving part.

A still further object of the invention is to provide plastic breakaway propeller blades which are easily repaired or replaced and are ofthe plug-in, pullout type.

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION To accomplish the above objects the pi-pitch cycloidal propeller of the present invention comprises a plurality oftiming gears held in synchronization by means of a timing belt which controls the angle of attack of the propeller blades (in this instance three blades). The typical gearbox is eliminated and a belt-driven timing gear speed reducer is employed. The unit operates in a flooded sea water environment and thereby eliminates the sealed housing heretofore required. The water lubricates plastic bearings which are used at every moving part. The plastic bearings are critical to the smooth and noiseless operation of the device.

The driving means for the cycloidal propeller includes a sun gear or central'pinion gear, which is the thrust directional controller, two idler gears and three propeller blade gears all held in synchronization by the timing belt. The pinion gear is one half of the diameter of the propeller blade gears; thus for every revolution of the pinion gear (or of the main propeller disc) the symmetrical propeller blades will rotate Each blade of a pi-pitch propeller operates at a constant rotational velocity of one-half the propeller r.p.m. (i.e., the sun gear). A unique timing belt-pulley arrangement was chosen to eliminate gears and their associated problems.

BRIEF DESCRIPTION OF THE DRAWING The drawing illustrates an exploded perspective view of a preferred embodiment ofthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The drawing, which illustrates a preferred embodiment of the invention, shows a belt-driven cycloidal propeller [0 including a plurality of timing gears held in synchronization by means ofa timing belt 12 which controls the angle of attack of propeller blades [4, I6 and 18. The timing belt 12 and the gearing system are located within a one-piece cylindrical housing 20 which includes a cylindrical propeller gear housing 22 and a fixedly attached driving pulley 24,

The gearing system includes three

propeller blade gears

26, 28 and 30 which are symmetrically mounted within the periphery of propeller gear housing 22. Two idler gears 32 and 34 are also mounted within housing 22 to provide tension on timing belt 12.

To control the pitch movement of the timing belt 12 and

propeller blade gears

26, 28 and 30, a pinion gear 36 is located in the center of propeller gear housing 22. The pinion gear 36 is pinned to a blade pitch control shaft 38, so that rotation of shaft 38 rotates pinion gear 36 and timing belt 12 to change the pitch of

propeller blades

14, 16 and 18.

Two propeller discs 40 and 41 are mounted on shaft 38 on both sides of gear housing 22 and support the gearing system. The discs 40 and 41 may be of the same diameter as gear housing 22 with holes 42 formed therein to allow the inflow of sea water. Or, discs 40 and 41 may be of a smaller diameter than housing 22 and thereby allow sea water flooding of gear housing 22.

Propeller disc 40 mounts the propeller blades I4, 16 and IS on water-lubricated

plastic bearings

44, 46 and 48 located in propeller disc 40. The propeller blades [4, l6 and 18 have

studs

50, 52 and 54, respectively, formed thereon for projection through their

respective bearings

44, 46 and 48 and into their respective

propeller blade gears

26, 28 and 30, which are in axial alignment with the bearings.

Blade studs

50, 52 and 54 are keyed to their respective propeller blade gears 26, 28 and 30 in order to control the pitch of propeller blades [4, l6 and I8. Slots 56 are formed in propeller discs .40 and 41 to adjust timing belt l2.

Propeller blades l4, l6 and 18 are of the plastic breakaway type which are easily repaired with suitable epoxy or they are easily replaced. Also, blade studs 50. 52 and 54 are of the plug-in. pullout type and provide a detachable means of connection to propeller blade gears 26, 28 and 30.

The driving assembly consists of a motor 58 which drives a belt 60. A plastic all support bearing 62 provides a boss which is connected to the boat.

The propeller and motor housing are of sand castings of 356T6 aluminum protected by hard anodize. The 30-inch propeller discs 40 and 41 are also hard anodized aluminum. Water-resistant plastic is molded over the aluminum blade cores to combine the good virtues of metal and plastic. Moreover water-resistant plastic was used whenever possible to eliminate the corrosion problem. The propeller blades [4. l6 and 18 were designed with a modified elliptical plan form and an elliptical cord with an aspect ratio of to I.

In operation the motor 58 drives a belt 60 to rotate the onepiece housing 20, the gearing system mounted therein, the propeller discs 40 and 4t and propeller blades l4, l6 and [8. While the propeller blade gears 26, 28 and 30 are orbiting in this manner, if a change in pitch is desired, control shaft 38 is rotated (manually or by a servomotor). This will rotate central pinion gear 36 and move the timing belt 12 to synchronize the rotation of propeller blade gears 26, 28 and 30. Since the propeller blades l4, l6 and 18 are keyed to

gears

26, 28 and 30, they will rotate together to change the pitch of propeller blades l4, l6 and [8. In this manner, the propeller blade gears are rotated to change the pitch of the blades while they are orbiting with the housing 20.

From the above description it is apparent that the cycloidal propeller of the present invention accomplishes the objective of operation in a flooded sea water and sandy environment and thereby eliminates the need for protective sealed housing and a plurality of meshing gears. Also the objective of a smooth-running and noiseless operation is accomplished through the use of a timing belt and water-lubricated plastic bearings at every moving part.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings.

What is claimed is:

l. A cycloidal propeller and driving means therefor, comprising:

a rotatable propeller gear housing whose interior is open to a sea water environment;

a plurality of timing gears mounted in said housing to rotate therewith;

a timing belt engaging said gears to hold said timing gears in synchronization;

a plurality of breakaway propeller blades detachably connected to said timing gears and rotatable therewith; water-lubricated plastic bearings to mount said blades; means for rotating said gear housing; and

means for controlling the pitch of said propeller blades.

2. A cycloidal propeller and driving means therefor as recited in claim I, wherein said plurality of timing gears comprises a central pinion gear and a plurality of orbiting propeller blade gears, all of which are mounted on waterlubricated plastic bearings.

3. A cycloidal propeller and driving means therefor as recited in claim 2. wherein said propeller blades have keyed studs mounted thereon for plug-in, pullout type of connection to said gears.

4. A cycloidal propeller and driving means therefor as recited in claim 3, wherein said pitch control means includes a shaft to rotate said central pinion gear which causes said orbiting propeller blade gears to rotate about their own axes and change the pitch of said rotating propeller blades.

5. A cycloidal propeller and driving means therefor as recited in claim 2, wherein said plurality of timing gears comprises two idler gears wherein one of said idler gears is adjustably mounted to said housing.

6. A cycloidal propeller and driving means therefor as recited in claim 3, wherein said propeller blades are exterior of said rotatable propeller gear housing.

tart-it

Claims

1. A cycloidal propeller and driving means therefor, comprising: a rotatable propeller gear housing whose interior is open to a sea water environment; a plurality of timing gears mOunted in said housing to rotate therewith; a timing belt engaging said gears to hold said timing gears in synchronization; a plurality of breakaway propeller blades detachably connected to said timing gears and rotatable therewith; water-lubricated plastic bearings to mount said blades; means for rotating said gear housing; and means for controlling the pitch of said propeller blades.

2. A cycloidal propeller and driving means therefor as recited in claim 1, wherein said plurality of timing gears comprises a central pinion gear and a plurality of orbiting propeller blade gears, all of which are mounted on water-lubricated plastic bearings.

3. A cycloidal propeller and driving means therefor as recited in claim 2, wherein said propeller blades have keyed studs mounted thereon for plug-in, pullout type of connection to said gears.