US 2415380 A
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Description (OCR text may contain errors)
Feb. 4, 1947. M. WEBER 2,415,380
PROPELLER BLADE Filed Nov. 15, 1944 3 Sheets-Sheet l Z4 Max IVE 3&6?
Feb, 4,. 1947. M, WEBER PROPELLER BLADE Filed Nov. 15, 1944 Sheets-Sheet 2 N UTRAL ONE Feb. 4, 1947. M. WEBER 2,415,380
PROPELLER BLADE Filed Nov. 15, 1944 s Sheet's-Shet 3 Patented Feb. 4, 1947 2 Claims.
This invention relates to propeller blades and is an improvement over the blade embodied in my co-pending application Serial No. 464,813, filed November 3, 1942, for Propellers which issued on Get. 2, 1945, as Patent No. 2,386,154.
An object of this invention is to provide a propeller blade structure wherein the blades are formed with outer reversely pitched tip portions so as to eliminate fatigue strain on the blades.
Another object of this invention is to provide a propeller blade structure wherein each blade is formed with a relatively wide and deeply pitched draft portion, the trailing edge of each blade extending rearwardly of the hub.
A further object of this invention is to provide a propeller blade structure which will generate a relatively narrow draft of high velocity air.
A further object of this invention is to provide a propeller blade structure wherein the hub or the central portion of the blade structure is formed as a continuation of the blades so as to thereby provide a swift helically moving vacuum stream travelling together with the dynamic pressure of the surrounding air so as to thereby produce cyclonic air motion in principle.
To the foregoing objects, and others which may hereinafter more fully appear, the invention consists of the novel construction, combination and arrangement of parts, as will be more specifically referred to and illustrated in the accompanying drawings, but it is to be understood that changes, variations, and modifications may be resorted to which fall within the scope of the invention as claimed.
in the drawings:
Figure l is a detail front elevation of a propeller constructed according to an embodiment of this invention.
Figure 2 is a detail side elevation of the propeller.
Figure 3 is a front elevation partly in section of one or" the blades.
Figure 4 is a sectional view taken on the line l-d of Figure 3.
Figure 5 is a sectional view taken on the line 5-5 of Figure 3.
Figure 6 is a sectional view taken on the line 6-6 of Figure 3.
Figure 7 is a sectional view taken on the line l---'! of Figure 3.
Figure 8 is a sectional view taken on the line 88 of Figure 3.
Figure 9 is a sectional view taken on the line 8-9 of Figure 3.
Figure 1G is a sectional view taken on the line lillll of Figure 3.
Figure 11 is a sectional view taken on the line iill of Figure 3.
Figure 12 is a sectional view taken on the line iZ-IZ of Figure 3.
Referring to the drawings, the numeral l5 designates generallya hub whichis adapted to be mounted on a shaft such as a motor shaft, or the like. The hub has projecting radially therefrom a plurality of impeller blades generally designated as l6. The blades it are of like construction and each includes an elongated body ll which is formed with an arcuate leading edge 53, an arcuate leading edge E9, the edge is being oppositely curved from the leading edge E3.
The body H is formed with a pitch which decreases in degree from the inner portion 23 thereof to the outer portion, the inner portion of the blade it having substantially deep pitch and this pitch gradually decreasing towards the outer end of the blade.
At a point spaced inwardly from the outer end of the blade it there is a neutral zone 2! wherein the pitch of the blade is zero and the neutral portion 2! rotates in a plane at right angles to the longitudinal axis of the hub lb. The blade i6 is formed with a tip 22 which is of a pitch reverse from the pitch of the body ll, the pitch of the tip 22 being a relatively shallow pitch and designed for the purpose'of relieving fatigue at the tips of the blades, in addition to providing a means for counter-balancing the thrust caused by rotation of the blade Hi. The neutral zone 2! which is shown by dot and dash lines in Figure 3 is at a point substantially equal to onethird the length of the blade 86. The reversing of the pitch of the blade also provides a means whereby air at the outer ends or tips of the blades will be drawn inwardly towards the axial center at the rear side of the blade, so that the air forced forwardly by rotation of the propeller will enter the suction zone at the rear side of the propeller from both the rear side and the outer ends of the blades.
The hub 55 of the propeller is also formed with a plurality of blades 23, which are formed as continuations of blades it. The central or hub blades 23 have a substantially deep pitch, and the blades 23 are extended forwardly and terminate at a central point 2 3, which isthe axis of the hub lb. The trailing edge E9 of each blade is projected rearwardly from the hub i5, so as to provide a greater depth for each blade thereby increasing the effectiveness of each blade.
The hub blades 23 at their rear edges merge with the trailing edge 19 in a. concave curvature, as indicated at 25, the blades [6 at the point of mergence between these blades and the hub blades 23 being narrower than at their intermediate portions.
With a propeller structure as hereinbefore olescribed the propeller will provide a central air column which is thrust'forwardly and will also provide an outer substantially cylindrical column of air, which is alsothrust forwardly, but the outer column of air will be moving forwardly at a speed less than the central air column. This I variation in the speed of the movement of the air columns is caused by the deep pitch of the center blades, whereas the radial blades extending from the hub while having a relatively deep pitch are pitched less than the hub blades.
The reversing of the pitch, as indicated at 22, in the tip portions of the blades is of such character that there will not be an undue drag on the tips of the blades due to the greater travel of the tips of the blades. The blades are reversed in pitch at their tips not only for the purpose of causing inward movement of air on the rear sides of the blades, but also to provide a counter-balancing thrust, so that the propeller will substantially float and will not form a heavy thrust on the motor shaft. This reversing of the pitch of the blades also provides a means whereby the propeller may be rotated at a very high speed and the speed of the propeller will not cause metal fatigue.
.In Figures 7 to 11, inclusive, there is disclosed the variation in the pitch of the body'll from the outer to the inner portion thereof, this pitch increasing towards the inner end of the body H, where this body merges with the hub blades 23.
What I claim is:
1. A propeller comprising a hub, and a plurality of blades carried by said hub, said blades at their inner ends extending forwardly of said hub, and terminating at substantially the axial center of said hub, the pitch of each blade gradually decreasing from the hub axis toward the outer end thereof, each blade comprising a forwardly pitched forward thrust area for the major length thereof, a reversely pitched tip area and an intermediate neutral area defining a neutral zone between the forward thrust area and the reversely pitched tip area, the pitch of said tip being substantially less than the average forward REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 528,253 Jay Oct. 30, 1894 553,131 Parini Jan. 14, 1896 1,506,937 Miller Sept. 2, 1924 1,933,948 Weber Nov. '7, 1933