Windmill blade

A self-starting windmill of the vertical axis type. Upstanding helical in configuration, pivotally mounted outer blade members surround a central, rotatably mounted shaft are connected to the shaft by radially disposed strut members. Arcuate in planform, pivotally mounted inner blade members are mounted radially inwardly of the outer blade members in a collective triangular configuration and have their respective convex surfaces facing toward the shaft. A weight member and a spring member bias a preselected edge of each outer blade member against wind force.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to windmills, generally, and more particularly 
relates to a windmill construction of the vertical axis type having an 
upstanding set of rotatably mounted outer blades and an upstanding set of 
conjointly rotatable inner blades positioned radially inwardly of the 
outer blades. 
2. Description of the Prior Art 
Vertical axis windmills in general are well known, of course, and have been 
described in numerous U.S. and foreign patents. 
For example, U.S. Pat. No. 2,515,713, awarded in 1950 to Johnson and other, 
discloses a mixer device having helical blades of the type that could be 
adapted for a windmill construction. 
U.S. Pat. No. 4,115,032, issued in 1978 to Lange, shows a windmill having 
blades that rotate about a vertical axis. The Lange device converts the 
energy of wind into mechanical rotation of an upstanding output shaft for 
driving an electric generator, a pump, or the like. 
A U.S. patent awarded in 1981 to Dereng, U.S. Pat. No. 4,264,279, discloses 
a self starting wind turbine having a single blade rotatable about a 
vertical axis. 
Another U.S. patent to Lange, U.S. Pat. No. 4,543,042 (1985), discloses a 
windmill rotor of the vertical axis type having at least three main blades 
mounted symmetrically around a shaft which blades are bowed to define a 
generally spherical configuration. 
U.S. Pat. No. 4,281,965, awarded in 1981 to Stjernhom, discloses a 
cantilever mounted wind turbine having an interior stationary support 
column and a concentrically mounted rotatable rotor. 
None of the earlier patents known to the present inventor teaches a 
windmill having blades constructed out of a metal drum, nor do the patents 
of the prior art of which the present inventor is aware include mechanisms 
for maintaining a constant rotational velocity of the type disclosed 
hereinafter. 
It is an important object of this invention is to provide a mechanism that 
allows rotational movement of windmill blades at a constant, nonsurging 
speed, which speed is maintained independent of wind speed. 
Another object of this invention is to provide a simple method of 
constructing windmill blades from readily available materials. 
SUMMARY OF THE INVENTION 
The invention accomplishes these and other objects that will become 
apparent as this disclosure proceeds by providing a windmill that includes 
helical blades positioned around a rotatably mounted vertical shaft to 
which the blades are attached for conjoint rotation by radially disposed 
struts. 
A governor means includes a plurality of inner blade members having an 
arcuate plan form. 
The novel device provides various features and advantages. The windmill is 
self-starting since there is no need for the application of an external 
force other than wind force to set it in motion. 
Moreover, the blades of the windmill can be formed from a metallic drum, 
and any number of blades may be emplyed, including only one blade. 
The invention accordingly comprises the features of construction, 
combination of elements and arrangement of parts that will be exemplified 
in the construction hereinafter set forth, and the scope of the invention 
will be indicated in the claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 shows three blade members, collectively designated 12, of the novel 
windmill 10 arranged in a helical configuration with respect to shaft 20. 
The phantom lines appearing in FIG. 1 suggest the presence of a drum such 
as a fifty five gallon drum, it being understood that blade members 12 
could be cut from such a drum. 
Each blade 12 is fixedly secured for conjoint rotation to rotatably mounted 
shaft 20 by a plurality of radially disposed upper strut members 14 and 
lower strut members 16. 
Referring now to FIG. 2, a first embodiment of the governor mechanism for 
windmill 10 is shown. 
Each blade 12, only one of which is shown in FIG. 2 to simplify the 
drawing, is pivotally mounted as at 28 to its associated lower radial 
strut 16 and its associated upper radial strut 14. This pivotal mount 
enables each blade member 12 to pivot about pivot point 28, in response to 
wind forces indicated by directional arrows 30, while simultaneously 
rotating about shaft 20. 
Travel stop 26 limits the pivotal movement of each blade 12, and a pair of 
horizontally disposed, vertically spaced spring members 22, only one of 
which is shown in FIG. 2, extend from vertically spaced points on the 
trailing edge of each blade 12 to associated upper or lower strut members 
14 and 16. 
A lead weight 24 is fixedly secured to the trailing edge of each blade 12 
adjacent each upper and lower spring 22 as depicted. When wind exerts 
pressure against the blade members 12, such pressure is counteracted by 
the tension of spring 22, the gravitational force of lead weight 24 and 
the centrifugal force generated by the rotation of the outer blade members 
12. Thus, the assembly represents a servomechanism since increased wind 
pressure will meet with increased resistance so that s substantially 
constant rotational velocity is achieved. The position of weight member 24 
can be adjusted by suitable means to vary the counteracting force. The 
adjustability of weight member 24 represents a fine tuning means for the 
governor mechanism. 
A second embodiment of the governor mechanism is shown in FIGS. 3 and 4. 
This mechanism includes governor blade members 34 disposed in a triangular 
configuration as shown in FIG. 4. Each blade member 34 has an arcuate 
planform and the respective convex surfaces of said blade members face 
shaft 20 as shown. In the position shown in FIG. 4, the wind is not 
blowing or is blowing lightly because the blade members 34 are in their 
respective equilibrium, or unpivoted positions in said FIG. 
The upper end of each blade member 34 is mounted to its associated radially 
disposed governor bar member 36 (which governor bar members extend 
radially from shaft 20 adjacent the upper strut members 14) as at 38: the 
lower end of each inner blade member 34 is pivotally secured to its 
associated lower strut member 16 as at 40. 
This mounting enables blade members 34 to pivot in response to wind 
pressure. Such pivotal movement of blades 34 alters their "at rest" 
triangular configuration. When blades 34 are in their unpivoted position, 
as depicted in FIG. 4 as a foresaid, their individual and collective 
resistance to wind pressure is low. When blade members 34 pivot in 
response to wind pressure, their individual and collective resistance 
increases. Such increased resistance enables a substantially constant 
speed rotation of windmill blades 12 because the resistance to the wind 
offered by each inner blade member 34 is proportional to the wind speed. 
Each inner blade member 34 has a center of gravity C.G. and a center of 
effort C.E.; these centers flank the pivotal axis 44 of each blade 34 as 
shown in FIG. 3 and serve to balance the blade members 34. 
The assembly thus has two governor mechanisms, i.e., the biased pivotal 
mounting of the outer blades 12 and the uniquely shaped inner blade 
members 34. Both governing features could be provided in a single 
windmill, or either mechanism could be provided to the exclusion of the 
other. 
It will thus be seen that the objects set forth above, and those made 
apparent from the foregoing description, are efficiently attained and 
since certain changes may be made in the above construction without 
departing from the scope of the invention, it is intended that all matters 
contained in the foregoing description or shown in the accompanying 
drawings shall be interpreted as illustrative and not in a limiting sense. 
It is also to be understood that the following claims are intended to cover 
all of the generic and specific features of the invention herein 
described, and all statements of the scope of the invention which, as a 
matter of language, might be said to fall therebetween.