US 2393234 A
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Description (OCR text may contain errors)
'Jan. 22, 1946. w, s, ss 2,393,234
CONTRA -TURNING PROPELLER MECHANISM Filed Jan. 15, 1943 2 Sheets-Sheet 1 gwumi Zilliam difi r qe s;
Jan, 22,1946. w. s. BURGESS 2, 93
CONTRA-TURNING PROPELLER MECHANISM 2 Sheets-Sheet 2 Filed Jan.. 13, 1943 ama: Sawe38, m M.
Patented Jan. 22, 1946 CONTRATURNING PROPELLER MECHANISM William Starling Burgess, Washington, D. (3., as-
signor to Weaver Associates Corporation, Washington, D. 0., a corporation of Maryland Application January 13, 1943, Serial No. 472,289
Claims. (01. 114-163) The present invention relates to propulsion means for vessels or other craft adapted for movement in or upon a fluid medium. Although not confined in its broadest aspects thereto, the invention relates primarily to marine propulsion means. More particularly, it is concerned with improvements in propulsion means of the contraturning screw-propeller type. i
It is well understood by those skilled in the art that marine propulsion devices, such asthe propeller and the paddle wheel, operate upon the broad principle of the reaction of the instrumentality upon the adjacent water in the transmission of the energy of the propelling engine to the water. This transmission of energy results in a sternward acceleration of the water, referred to as the slip stream. In this transmission of energy certain losses inevitably occur, the principal ones of which are frictional resistance of the water to the revolving blades, the disturbance of the streamline iiow and the friction of the slip stream itself with the surrounding water, i. e., the friction in the water itself.
It is well understood that the slip stream produced by a screw propeller has two components of motion, a sternward motion and a revolving motion with the result that the water in the slip stream follows a generally spiral path.
Only the sternward component of movement is useful, since it alone results from forwardly directed reaction forces in the propeller blades' The revolving component in the slip stream is a total loss and represents wasted energy.
The principle of the contra-turning propelleraims to utilize this wasted energy and to enable the forces in the revolving body of water in the slip stream to do useful work. Contra-turning propellers have other well known advantages, one of the principal ones of which is that greater power may be delivered to the surrounding body of water by instrumentalities of much smaller overall dimensions (one-half or less). As a result, smaller propellers and lighter supporting and driving devices may be employed.
Although the advantages flowing from the use of contra-turning propellers have long been appreciated by those skilled in the art, propulsion devices of this type have enjoyed little or no practical use, prior to the present invention, for the reason that the difficulties which have arisen in connection with power transmission means, supporting means, journal means and lubricating means have proven insuperable. With the sole exception of its application to torpedoes, the contra-turning propeller system of marine propulsion has not been employed in the commercial or practical art.
The main reason for the lack of use of the system is that conventional ships have always been driven by substantially horizontal propeller shafts connected at their forward ends to suitable prime movers and having propellers on their rear ends. With such a construction, the only way in which coaxial contra-turning propellers can be mounted is to have the forward propeller fast upon a rotating, hollow shaft or sleeve and the aft propeller fast upon a coaxial shaft disposed interiorly of the first-mentioned shaft and rotat- 'ing in the opposite direction. In constructions of this type, insuperable problems arise in connection with providing suitable bearings for the two shafts, supplying lubricant thereto, and providing water seals around the outer shaft and in the space between the two shafts. Moreover, with large ships, it is difficult, if not impossible, to provide sufiiciently strong shafts to transmit the necessary power, without making the shafts unduly large, cumbersome and expensive. In view of these difiiculties, the practical ship propulsion art has found it more economical to employ single propellers mounted on independent shafts in spite of the inherent inefiiciency of this type of construction.
The principal object of the present invention is to obviate all of 'these difficulties and to pro vide a marine propulsion system which has all of the advantages of the contra-turning propeller system.
A further object of the invention is to provide improved supporting means for contra-turning propellers and to provide improved and simplified driving and lubricating means for the propellers.
A further object of the invention is to provide independent supporting means for each propeller of a pair of contra-turning propellers, to the end that either of the propellers may be removed for replacement or repair independently of the other.
A further object of the invention is to provide means whereby the independently supported propellers may be mounted in closely spaced, face to face relation, in order to gain the maximum efficiency from the contra-turning propeller principle.
A further object of the invention is to provide, if desired, independent prime movers or driving means for the individual propellers of a pair of contra-turning propellers.
A further object of the invention is to produce a shallowed draft vessel, such as a river barge or tug, having contra-turning propellers mounted in an improved manner in a propulsion tunnel or channel, without increasing the draft of the vessel. Another object is to improve the steering characteristics of such a vessel by the use of a forward rudder, positioned directly in alignment with the propellers, in the slip stream when the ship is moving astern.
Other and further objects and advanta es of the invention will be apparent to those skilled in the art from a consideration of the following description of a specific embodiment of the invene tion, illustrated in the accompanying drawings, in which:
Figure 1 is a side elevation of a shallow draft river tug having the invention embodied therein.
Figure 2 is a horizontal section and plan view, taken substantially On line 2-2 of Figure 1.
Figure 3 is a vertical section and elevation, on an enlarged scale, taken substantially on line 3-3 of Figure 2, and
Figure 4 is a transverse section, taken on line 44 of Figure 3.
Although the invention is not confined to its use in combination with a shallow draft barge or tug, or otherwise with a vessel having a propulsion channel or tunnel in its bottom, in the embodiment specifically disclosed herein, a vessel of that type is shown. The hull l may be in substantially the form of a scow, comprising a flat bottom H, sloping upwardly as at l2 toward a substantially square bow l3, and an upwardly sloping after body I4 terminating in a square stern l5. The deck [5 may support the usual cabin i1 and an engine room l8, positioned aft. An upper cabin l9, may contain the officers quarters, galley and mess, and may support an upper pilot house 20, Obviously, any other arrangement of cabins may be employed.
The after body portion of the hull preferably has a bottom shaped to provide a pair of substantially parallel propulsion tunnels or channels having forwardly and downwardly sloping entrance end walls 26, laterally inclined side walls 21, 28 and an arcuately curved top wall 29 (Fig. 4). The tunnels, of course, are open at their rear ends, and a pair of main steering rudders 30. are positioned therein, each mounted foroscillation upon a vertical axis coinciding with the longitudinal axis of a tunnel. A monkey rudder 3| is similarly mounted adjacent the forward end of each tunnel.
As shown in Figure 3, the upper wall 29 of the tunnel 2-5 is interrupted at two spaced points to provide upwardly opening wells 35, 36, defined by walls 37, 38, which may extend upwardly above the deck IS. The wells constitute chambers for the reception of propulsion units which may be removably supported by the Walls 31, 38 thereof. Each unit preferably comprises an upper housing 40 and a lower housing 4|, connected together by a joint 42 of any approved design. The upper housing 40 includes a gear casing 43, a vertical shaft bearing 44 and a plurality of horizontal shaft journals 45. Similarly, the lower housing 4| carries a pair of vertical shaft bearings 46, 4'! and horizontal shaft bearings 48, 49.
In the upper housing 40, there is a vertical drive shaft journalled in the bearing 44 and having a bevel gear 5| fast on its upper end, The bevel gear may be driven by a plurality of pinions 52 fixed to shafts 53, connected through reversing gears 54 to one or another of a plurality of engines 55-58, which may be gasoline engines of standard automotive or marine type, at present readily available on the market. Of course, the
invention is not restricted to the use of such engines, as any approved prime mover may be employed to drive the shaft 50 or its equivalent, such as a steam engine, a turbine, a Diesel engine or an electric motor.
In the lower housing 4| there is a vertically disposed drive shaft 60, journalled in the bearings 46, and 41 and connected to, the upper shaft 53 by a suitable shaft coupling 6!. The shaft 60 carries a pinion 82 on its lower end, in mesh with a larger pinion 63, fast on a stub propeller shaft 64, journalled in bearings 48, 49.
It will be understood that the parts so far described are substantially duplicated in the fore and aft assemblies and that if the plan shown diagrammatically in Figure 2 is adopted, four of these assemblies will be provided, each driven by one or more prime movers having substantially the same power. If desired, the fore and aft drive assemblies may be interconnected, by shafting and gearing to rotate in opposite directions in unison,- Moreover, a single, substantially horizontal drive shaft may be employed to drive both power transmission mechanisms, by simplyhaving worm gear power take-olfs, on the single shaft, one for each vertical shaft 50.
It will be noted that the propeller shaft 640. of the forward assembly projects rearwardly relative to the lower housing M and that the propeller shaft 64 associated with the aft assembly projects forwardly. Each shaft carries a pro.- peller 65v or 6511, comprising a hub 5.8. secured to. the shaft by any appropriate means, such as a. nut Bl, screwed onto the end of the shaft and disposed in an enlargement 68 in the end face of the hub. The propellers may be of substantially identical construction as to size, number of blades and pitch. However, since one faces forwardly and the other faces rearwardly, they will be of opposite pitch, in an operative sense so that they may be driven in opposite directions, to produce the aforementioned, desired contraturning propeller effect. It must be understood, of course, that the propellers may be of different pitch, if desired.
In order to secure the maximum efficiency from the contra-turning propellers, their blades, 69 are preferably raked or tipped axi ll beyond the end face of the propeller hub, so that, when assembled in the relation shown in Figure 3; their tips are quite closely spaced, the blade of the forward propeller being raked rearwardly and those of the rear propeller forwardly.
In order to maintain the streamline effect of the lower, gear casing portion 70 of the lower housing 4! and the propeller hubs 66., the space between the end faces of the hubs is preferably occupied by a cylindrical fairwater or sleeve H, carried by one hub for rotation therewith and spaced a slight distance, as indicated at 12, from the other. The forward gear casing Til carries a streamlined nose piece 13, removably secured thereto by any appropriate means, and the gear case of the rear assembly similarly carries a streamlined tail piece 14.
Thefairwater sleeve H is re-movably secured to the associated propeller hub, by screw threads, set screws or any appropriate means, to the end that it may be removed, if it is desired to pull one or the other propeller. In such case, either propeller may be removed by removing the retaining nut 61 and pulling the propeller from its shaft 54 or 64a, until the end faces of thebro: pellers are in substantial abutment, whereupon the propeller may be dropped from the tunnel 25. Obviously, the propellers must be turned so that the blades are out of alignment, in staggered relation, when this operation is being performed.
Although the invention is not limited to the particular housing-supporting means shown in the accompanying drawings, this arrangement is entirely suitable and is preferred in many constructions. The upper gear casing 43 may conveniently be mounted upon a substantially circular disc 80, supported by the cylindrical wall 3'! or 38 of the well. Preferably, the discs 80 and the housings 43 are rigidly secured against rotation relative to/the walls of the associated well, to prevent the lower assemblies and propellers from being disaligned in use. The main propulsion thrust of the propellers, however, is absorbed by a, heavy thrust bearing which may conveniently take the form of an inflated pneumatic ring, such as an automotive truck tire 82, mounted upon a. rim 83 surrounding the housing 40 and bearing against the wall 31 or 38 of the associated well. This arrangement facilitates installation, since the tire, when deflated, may readily slide within the wells, but will make firm contact therewith when inflated.
The rudder 30 may be of conventional design, but the monkey rudder 3| of the present invention, which is used when the ship is moving astern, has marked advantages over prior constructions of similar type, since it may be positioned for oscillation about an axis in the same plane as the axis of rotation of the propellers. Heretofore, because of the necessity for a propeller shaft extending into the tunnel, the monkey rudder was divided into two sections, one above and the other below the shaft or one on either side of the shaft. The absence of a horizontally extending propeller shaft makes it possible to employ a single, relatively large monkey rudder in each tunnel, ahead of the propellers therein.
It will be appreciated that an arrangement similar to that shown in the accompanying drawings greatly simplifies the supporting and driving means for contra-turning propellers. Concentric shafts and sleeves or tubes are entirely eliminated. The driving gears, shafts and bearings may be lubricated by a splash system or by a simple forced feed system, with a pump return from the lower gear casing 10. The parts may readily be made-strong enough to transmit the power required to drive the propellers, without unduly increasing their size and mass.
It must be understood that the invention is not limited to the details of construction shown in the accompanying drawings and described above, but includes all modifications coming within the scope of the appended claims and their equivalents.
1. Ship propulsion means comprising independent supports projecting downwardly from the ship's bottom in spaced apart, longitudinally aligned relation, said supports terminating at their lower ends in substantially cylindrical, streamlined, coaxial casings, independent propeller shafts journalled for rotation in said casings, propellers carried by the shafts and having hubs disposed in face to face relation and constituting streamlined continuations of the casings, and fairwater means in the space between the propeller hubs.
2. Ship propulsion means comprising independent supports projecting downwardly from the ships bottom and disposed in spaced apart, fore and aft alignment, propellers carried by said supports and mounted for rotation in the space therebetween on a common fore and aft axis, and means for rotating the propellers in opposite directions, each of said propellers comprising a hub and blades projecting outwardly therefrom and raked in an axial direction, to rotate in closely spaced relation to the blades of the other propeller.
3. Ship propulsion means comprising independent housings projecting downwardly from the ship bottom in spaced apart, fore and aft alignment and terminating at their lower ends in streamlined coaxial casings, and independent propellers carried by the casings in the space between the housings and journalled for rotation on the casing axis, said propellers comprising hubs projecting toward each other from the casings and constituting continuations thereof and disposed in face to face relation, and blades projecting outwardly from the hub and raked axially toward the blades of the other propeller to rotate in closely spaced relation thereto.
4. Ship propulsion means comprising independent supports projecting substantially vertically downwardly from a ships bottom and disposed in fore and aft alignment, substantially cylindrical propeller shaft housings carried by the lower ends of the supports, a streamlined nose and tail carried fore and aft by the respective housings, stub-shafts joumalled in the housings, propellers carried by the shafts in face to face relation for rotation in opposite directions in the pace between the supports, said propellers having cylindrical hubs of a diameter substantially equal to the cylindrical housings, and a cylindrical sleeve of the same diameter carried by one of the hubs and substantially filling the space therebetween.
5. In combination, a ship having a propulsion tunnel or channel in the aft portion of its bottom, a pair of spaced apart struts projecting into the tunnel and disposed in fore and aft alignment, independent propellers carried by the struts and disposed substantially in face to face relation, means for rotating the propellers in opposite directions, a running rudder in the tunnel positioned aft of the propellers and a monkey rudder in the tunnel positioned forward of the propellers in axial alignment therewith.
WILLIAM STARLING BURGESS.