US2153055A - Propeller - Google Patents

Description

April 4, 1939. H. WE-ISQSMANN PROPELLER Filed April 6, 1938 2 Sheets-Sheet l IINVENTOR. flerzry WZZJJWIdiZI WM J M ATTORNEY.

April 1939- H. WEISSMANN 2,153,055

PROPELLER 2 Sheets-Sheet 2 Filed April 6, 193

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Patented Apr. 4, 1939 UNITED STATES PATENT OFFICE PROPELLEB.

Henry Weissmann, Staten Island, N. Y.

Application April 6, 1938, Serial No. 200,398

9 Claims.

The present invention relates to marine propulsion and more particularly to an improved shaftless screw propeller.

Screw propellers which are generally used for marine propulsion comprise a hub secured to a drive shaft and three or four propeller blades projecting outwardly from the hub. One of the diiiiculties of such propellers is that the outer portions of the blades do most of the work while the inner portions serve primarily as a support or holder. greater at the outer portions thereof than at the inner portions, whereby the outer portions propel the vessel and the inner portions act as a drag and resist the movement of the propeller through the water. As a result, more power is required to move the vessel. Also, due to the fact that the peripheral speed is greater at the outer portion of the blades, the blades tend to Q0 churn the water or create a turbulent actiont causing vacuum pockets about the blades which decreases the efliciency thereof. This phenomenon is usually referred to as cavitation".

The present invention aims to overcome the 5 above difiiculties by providing an improved shaftless screw propeller.

An object of the present invention is to provide a shaftless screw propeller having a high operating efiiciency.

b Another object of the invention is to provide a simple, inexpensive shaftless propeller which is compact in construction, takes up a minimum amount of space, and 'is readily adapted for vessels of allsizes.

35 Another object of the invention is to provide a shaftless propeller having spaced screw blades of substantially true helical form.

Another object of the invention is to provide propeller blades having a greater surface area 0 effective to propel the vessel and thereby increase a the efliciency of the propeller.

Another object of the invention is to minimize cavitation and the decreased emciency incident thereto. l

45 Another object of the invention is to provide an improved casing for a shaftless, propeller, I

which can be readily connected to the hull of a vessel.

A further object of the invention is to provide 50 an improved drive means for a shaftless'pi-opeller.

, Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various 55 advantages not referred to herein will occur to The peripheral speed of the blades is one skilled in the art upon employment of the invention in practice.

A preferred embodiment of the invention has been .chosen for purposes of illustration and description and is shown in the accompanying draw- 5 ings, forming a part of the specification, wherein Fig. 1 is an end view partly in section, illustrating a preferred embodiment of the invention;

Fig. 2 is a sectional view taken along the line 2--2 of Fig. 1, illustrating details of the propeller l0 casing;

Fig. 3 is a perspective view of one of the blade members;

Fig. 4 is a fragmentary end view illustrating a modified propeller casing; and I 15 Fig. 5 is a sectional view taken along the line 5-5 of Fig. 4.

Referring to the drawings and more particularly to Figs. 1, 2 and 3, there is shown the hull I of a vessel having a pair of shaftless screw pro I pellers 2 at the stern thereof (Fig. 1) By shaftless it is meant that the propeller blades are not integral or secured to a hub mounted on a drive shaft. The two propellers shown are substantially alike and only one of them need be described in detail. Also, it will be understood that, for example, one, two or three or more propellers may be used depending upon the size of the vessel.

The shaftless propeller illustrated herein preferably comprises a plurality of blade members 4 bolted, welded or otherwise secured to a rotatable ring member 5, and a casing 6 having a channel I (Fig. 2) for receiving the ring member 5. These parts will now be described in detail.

The blade members 4 are helical or spiral in shape (Fig. 3) and when rotated act like a screw to propel the vessel through the.water. Preferably, the blade members are circumferentially extending segments of a substantially true helix and have a true screw action. At any point along the length of the blade, the surface at a transverse section is a straight line inclined withmespect to the mounting ring (Fig. 2). The blade members do not have any portions which are parallel to the plane of rotation of the ring member. Such portions would do nothingtowards advancing the vessel. Also, the blade members do not have any portions which are perpendicular to the plane ofrotation or extend fore and aft with respect to the vessel. Hence, the blade members do not have any portions which would produce a threshing or paddle wheel effect to merely churn the water like arotary pump without contributing to the advance of the vessel.

By eliminating portions which. might cause a churning action, cavitation is decreased and the eiliciency of the propeller is increased.

Another advantage of the propeller described herein, is that the blade members are mounted on the inner periphery of the ring member and are spaced away from the center of the ring so that the water can flow freely through the open space between the blades. The blades, by being spaced from the center, can do the work of a propeller'normally having a larger diameter than the ring. As compared with a propeller-having blades of equal surface area mounted on a. central shaft, the efiective area of the present blades is more than twice as great. One of the reasons for this is that no blade portions are required for supporting the effective portions.

A further feature of the present invention, is that the leading edge 9 of the blades projects slightly radially inwardly at In and that the blade at the leading edge is slightly greater in width than at other portions. The inwardly projecting portion Ill of the leading edge is closer to the center of the ring member and rotates at a slower peripheral speed than other portions of the blade member. Consequently, the portion ill of the leading edge moves slowly while the portions following the leading edge rotate at a higher peripheral speed through the body of water. This causes the water to closely follow the contour of the blade and prevents the formation of vacuum pockets to decrease the slip between the blades and the water. In order to minimize any turbulent action at the trailing edges ll of the blade members, the ends H of the blades slope outwardly towards the ring member so that the blades are decreased in width; It has been found that by constructing the blade members in the above manner, the water offers a minimum amount of resistance to the forward or rearward movement of the propeller, and also that the streamlining of the blade members increases the propelling action of the blade mem-.

are spaced endwise to permit a free flow of water through the casing.-

The blade members preferably are provided with a base portion ll adapted to be seated in recesses H3 at the inner periphery of the ring member and adapted to be secured thereto by bolts IE or the like (Fig. 2). By placing the base portions of the blade members in recesses, the inner peripheral surface of the ring member is substantially fiush with the inner surface of the base portions and there are no portions which impede the propelling action of the blades.

The casing 6 for the ring member may be constructed in any suitable manner. The preferred embodiment of the casing may comprise a pair of substantially annular members i'l adapted to be secured together by suitable bolts i9 having their heads seated in a recess 20 to minimize resistance to the flow of water. Also, the outerends 2| of the casing members converge to reduce resistance to movement through the water to a minimum.

The casing members have opposed recess portions forming the channel I for the ring member and preferably each casing member has a ballbearing race 22 adapted to receive ball-bearings 24 to facilitate rotation of the ring member 5, and to sustain the fore and aft thrust occasioned by the rotation of the propeller in driving the ship forward or backward. Each of the casing members also has an annular groove 25 wherein a suitable packing member or gasket 26 is mounted, which is adapted to form a seal between the ring member and the channel (Fig. 2) to prevent water from getting into the casing. The groove and packing are shown conventionally in the drawingsas illustrative of means of sealing the casing to prevent seepage of salt water. Any

other known means of sealing the casing may be used, if desired.

In order to attach the casing members conveniently to the hull of the vessel, the casing members are provided with suitable flange or lug portions 27. ,The flange portions preferably con form to the shape of the hull and are adapted to be bolted or otherwise secured to the side or bottom oi the hull to securely mount the propeller casing. In addition, .a suitable bracket 28 may be secured to the casing members at 29 and to the hull of the vessel at 30.

The ring member carrying the propeller blades preferably is rotated by suitable gear means. Preferably, these means comprise a gear 36 mounted on the drive shaft 32 having a pair of gear portions 33 extending through an aperture 34 in the casing members adjacent the flanges 21! and engaging a pair of annular gear portions 36 on the outer periphery of the ring member 5. Intermediate the gear portions 33, there is a recess 31 adapted to receive a corresponding rib or annular projection 39 of the ring member which aifords additional structural strength. An advantage of the above construction is that the drive gear 3| is substantially smaller in diameter than the gear portions 36 of the ring member, so that the propeller is rotated at a lower speed than the shaft. This enables turbines having a relatively high speed of rotation to be connected directly to the drive shaft 32 while the drive gear and the gear portions 36 of the ring member act as reducing gears to reduce the rotary speed of the propeller.

In Figs. 4 and 5, a slightly diiferent casing construction is illustrated, which differs from the casing illustrated in the preferred embodiment, in that the casing members 42 are semi-circular instead of annular. Each casing member has the flanges 44 at the ends thereof which are adapted to be bolted to the respective flanges of the other casing member, as shown in Fig. 4. Such construction is'simple and very efiective in sealing against entry of sea water. The ball-bearing race d5 preferably is constructed separately and is continuous and circular in shape to eliminate connecting edges which would'impede movement of the ball-bearings. The packing members 25 preferably areannular to provide a tight contlnuous seal between the ring member and the casing. The casing members are adapted to be attached to the hull of the vessel in the same manner. as the casing members illustrated in the .type. The blades of the propeller are helical and have a screw-like action to propel the vessel. The blades are spaced equi-distantly to facilitate uniform rotation without excessive-strains on the eter. The. casing and drive connection for the propeller comprise a minimum number of parts 7 and can be readily assembled. Furthermore, the

propeller drive herein is suitable for small vessels such -as motor boats as well as large seagoing ships. The parts of the propeller are rugged in construction and can readily withstand any rough usage to which they may be subjected.

As various changes may be made in the form, construction and arrangement of the parts herein without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and. not in a limiting sense.

Having thus described my invention, I claim:

1. A propelling device of the class described,

comprising a rotatable ring member, and a pl urality of blade members secured to the inner periphery of said ring member, said blade members being wider at the leading edge than the trailing edge thereof.

2. A propelling device of the class' described,

comprising a rotatab1e annular member, a plurality of blade members of substantially true helical form, spaced circumferentially and secured to the inner periphery ofsaid annular member, said blade members having a leading edge and a trailing edge, the leading edge extending further radially inwardly than the trailing edge.

3. A propelling device of the class described, comprising a rotatable ring member and a plurality of blade members of substantially true helical form, spaced circumferentially and secured to the inner periphery of said ring memher, said blade members having an inwardly projecting leading edge and an outwardly sloping trailing edge.

4. A propelling device of the classdescribed,

comprising a ring member having a plurality of blade members secured to the inner periphery thereof, said blade members being wider at the leading edge than at the trailing edge, a casing having a channel for receiving-said ring member, means in said casing at the side of the channel rotating said ring member. v

5. A propelling device of the class described,

comprising a ring member having a plurality of blade members secured to the inner periphery thereof, a casing having a channel for receiving said ring member and provided with an aperture at the sidethereof adjacent said -channel, said tions on'the outer periphery thereof and an annular outwardly projecting rib intermediate said gear portions, a gear member extending into said aperture of the casing having a pair of gear portions adapted to engage the gear portions of said ring member and having an annular groove for receiving said rib, and means for rotating 'sai gear member to rotate said ring member.

6. A propelling device of the class described, comprising a ring member having a plurality of substantially true helical blade members secured to the inner periphery thereof, an annular casing having a channel for receiving said ring member and provided with an aperture at the side thereof adjacent said channel, said casing having flanges adjacent said aperture for securing said casing to the hull of a vessel, said ring member having a pair of annular gear portions on the outer periphery thereof and an annular outwardly prolecting rib intermediate said portions, a shaft, a gear member on said shaft extending into said aperture having a pair of gear portions adapted to engage the gear portions of said ring member and having an annular groove for receiving said rib, sealing members in said casing at said channel, and means for rotating said shaft to rotate said gear and ring members.

'7. A propelling device of the class described, comprising a ring member having gear teeth on the outer periphery thereof, a plurality of blade members, spaced circumferentially and secured to at the inner periphery thereof, a pair of semicircular casing members having a channel at the inner periphery thereof for receiving said ring member, a continuous circular ball-bearing race adjacent said channel, said casing members having a groove adjacent said ball bearing race, and.

sealing means seated in said groove adapted to engage said rotatable ring member to seal said channel.

9. A propelling device of the class described,

of diametrically split semi-circular casing members having a channel at the inner periphery for receiving said ring member and for receiving ball-bearing races, a'pair of continuous ball-bearing races. in said channel, said casing members having a. flange at each end thereof, and means for securing the flanges of one of said casing members to the respective flanges 'of said other casing member.

HENRY WEISSMANN.

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