US1454542A - Screw propeller - Google Patents

Description

May 8, 1923.

A. GRILLI SCREW PROPELLER Filed Oct. 2'7. 1921 R! m we ma 0 L E m H ATTORNEY.

Patented May 8, 1923.

PA ENT OFFICE.

ANGELO GRILLI, OF MILWAUKEE; WISCONSIN.

scanw PROPELLERT Application filed October 27, 1921.. Seria l'No. 510,910.

To all whom it may concern:

Be it known thatI, ANGELO GRJLLI, a subject of the King of Italy, residing at Milwaukee, in the county of Milwaukee and 6 State of Wisconsin, have invented a certain new and useful Improvement in Screw Propellers, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawin forming a part of this specification.

iis invention relates to screw propellers.

Objectionable vibration is not an uncommon occurrence in the ordinary bladed prollers so commonly used in ship propulsion.

is is due to the limited width of the blades and the consequent uncertain reaction thereof against the water. To avoid this, the

. use of a propeller having extended spiral surfaces has been proposed. The increased surface area thus provided reduces the vibration tendency, but in the propellers of this type heretofore constructed the increased resistance oifered by the water to this increased area of contact materially reduces the efliciency of the propeller.

The general aim of the present invention is the provision of an eflicient, smooth running propeller which will be free of the above noted objections. This is accomplished by the use of spiral surfaces of pregressively increasing width from the forward to the rear of the propeller.

Other objects and advantages will later ap ar.

85 no embodiment of this invention is illustrated in the accompanying drawings, in which:

Figure 1 is an end elevation of a screw propeller constructed in accordancewith the to present invention.

Figure 2 is a side elevation of the pro peller shown in Figure 1.

Figure 3 is a side elevation of the propeller turned through ,a ninety degree angle from the position of Figure 2.

The propeller selected for illustration includes a hollow hub 10 provided with the usual keyway 11 by which it may be secured to a drive shaft in the usual manner.

so The hub carries a pair of spirals 12 preferably formed as an integral part thereof and extending substantially from one end of the hub to the other. Each spiral terminates at its opposite ends in narrow straight edges 13 and 14.- radially disposed with respect to the longitudinal axis of the hub 10. It will be noted from an inspection of Figures 1 and 2 that the edges 13 are somewhat shorter than the edges 14, and that the radial width of each spiral surface increases progressively from one end 13 toward the other end until a maximum width is obtained at a point such as 15 near the rear end of the spiral. These spirals 12 are symmetrically arranged with respect to the hub so as to provide a 55 well balanced unit, and in the propeller shown each extends through an angle of substantially one hundred and eighty degrees about the axis of rotation and each is of substantially uniform pitch throughout. It will also be noted that the pitch of the spirals adjacent the hub portion is substantially the same as the pitch adjacent the outer edges. In fact, the pitch of the spiral surfaces is substantially the same at all diameters. In other words, each spiral surface maybe described as generated by a line maintained at a substantially constant angle with the axis of the propeller. In the propeller shown, this generating line is disposed normal to the axis of the propeller,

as indicated by the normal disposition of the radial edges 13 and 14 relative to the propeller axis. This formation of spiral surfaces produces a driving thrust upon the 35 water in a direction lengthwise rather than radially of the propeller.

In use, the propeller is so mounted that the edges 13 are positioned at the forward end thereof. As the propeller turns in a counter-clockwise direction (Fig. 1), both edges cut through the water and the rear surfaces of the spirals force the water rearwardly and cause an advance of the propeller. As the propeller advances with re spect to the water, the water is engaged by the surfaces of increasing 'area, with the result that a progressively increasing gri is established between the propeller an water. A very good traction is thus afforded. The gradual reduction in the radial width of the spiral surfaces be 0nd the point 15 of maximum width pro uces.

a progressively decreasing grip upon the water, thus avoiding an abrupt release and 106 resulting in a smooth action.

Various changes may be made in the embodiment of the invention hereinabove described, Without departing from or sacrificing any of the advantages of the invention as defined in the appended claims.

I claim:

1. A screw propeller having a hub and a pair of symmetrically arranged spiral surfaces carried thereby, each of said surfaces extending through substantially one hundred and eighty degrees about said hub, and each gradually increasing in Width from one end to a point in advance of the other end and then decreasing in Width from said point to the other end.

2. A screw propeller having a hub, a pair of spiral surfaces extending through substantially one hundred and eighty degrees about said hub, each surface having a substantially constant pitch at all diameters and having a progressively varying Width approaching a maximum between the ends thereof.

In Witness whereof, I hereunto subscribe my name this 24th day of October, 1921.

. ANGELO GRILLI.

Images