Weathervane with magnetic bearing

A weathervane includes a pointer (8a, 8b) provided with a vane and mounted for rotation about a vertical shaft (1) by a magnetic bearing. The magnetic bearing is comprised of a lower block (2a) made integral with the shaft (1) and of an upper block (2b) capable of rotating freely about the shaft. An upper face of the lower block (2a) and a lower face of the upper block (2b) are each provided with a permanent magnet (10a, 10b), which face each other and are oriented so that they have the same polarity. The pointer (8a, 8b) is made integral with the upper block (2b).

The present invention relates to a weathervane of a type comprised of a 
pointer provided with a vane and rotatingly mounted around a vertical 
shaft by means of a magnetic bearing of which the principle is known, as 
for example from the Japanese patent application 58-131426. 
For their rotation, weathervanes currently use glass or metal ball 
bearings, roller devices, or a simple shaft. 
Some of these devices are simple but unreliable, whereas others are more 
technical but also more costly. 
The objective of the present invention is to remedy the inconveniences of 
the known devices by proposing a rotary mounting means that is simple, 
reliable, and economical. 
This objective is attained by the weathervane according to the invention, 
in which the rotary mounting is realised by means of a magnetic bearing 
that is mounted on the vertical shaft and that is composed of a lower 
block which is held stationary to the vertical shaft and of an upper block 
capable of turning freely around said shaft, the upper surface of the 
lower block and lower surface of the upper block each being provided with 
a permanent magnet, said magnets being placed opposite one another and 
oriented so that their surfaces which are face-to-face are of the same 
polarity, the pointer being held stationary to the upper block. 
Due to this disposition, the perament magnets repel each other and 
constantly maintain a distance between the upper block and the lower 
block. It follows that the upper block with its dependent arrow can turn 
without friction around the vertical shaft. 
In a practical embodiment of the invention, the upper surface of the lower 
block presents a first recess adapted to receive a first permanent 
ring-shaped magnet and the lower surface of the upper block presents a 
second recess opposite the said first recess and adapted to receive a 
second permanent ring-shaped magnet, said first and second magnets being 
placed in their respective recesses so that their surface face-to-face are 
of the same polarity. 
Preferably, the second recess offers a sufficient depth to receive one or 
more magnets joined positive polarity against negative polarity, and/or 
one or more rings forming adjustment spacers. 
One can thus regulate the force with which the magnets of the upper and 
lower blocks repel each other and, consequently, the spacing between the 
upper block and the lower block. 
Favorably, the rings which form the spacers are made of Nylon. 
In a practical embodiment of the invention, the arrow is in two parts, each 
being held stationary to the upper block. 
The lower block and the upper block have a complementary exterior form 
giving a spherical form to the magnetic bearing which they constitute.

This FIGURE shows a vertical shaft 1 capable of being attached, for 
example, to the roof of a building. On this axis 1 are mounted a lower 
block 2a in the form of a part of a sphere and an upper block 2b, the form 
of which completes the sphere. The lower block 2a is provided with a 
threaded boring 3, in which a clamp screw is introduced to the point of 
penetrating into a conical recess 5 provided for in the shaft 1. The lower 
block 2a is thus held stationary in regards to the shaft 1. The upper 
block 2b is provided with a boring 6 traversing it from side to side which 
is adapted to receive, at each extremity, a dowel, 7a and 7b 
respectively,depending on the part of a pointer, 8a and 8b respectively. 
It is understood that, for example, the part 8a ends in an arrow point and 
that the part 8b ends in a vane. 
The upper surface of the block 2a is provided with a cylindrical recess 9a 
adapted to receive a permanent ring-shaped magnet 10a. 
Facing the recess 9a, the upper block is provided with a recess 9b adapted 
to receive a permanent ring-shaped magnet 10b. As can be seen, the magnets 
10a and 10b are positioned so that their surfaces of like polarity are 
face to face. 
The recess 9b is deeper than the recess 9a, which would eventually permit 
several ring-shaped magnets to be placed there which, in this case, are 
coupled positive polarity against negative polarity, or as is represented, 
a Nylon ring 11 forming an adjustment spacer. In playing with the 
thickness of this ring 11 and/or the number of magnets 10b, the force 
which is exercised between magnet 10a and magnet 10b can be regulated and 
by consequence the importance of the space 12 maintained between the lower 
block 2a and the upper block 2b. 
The lower block 2a and the upper block 2b each contain a bore 13a, 13b 
permitting the passage of the shaft 1. 
It is to be understood that when the force of the wind acts on the vane 
forming the extremity 8b of the pointer, the force is transmitted to the 
upper block 2b of the magnetic bearing and that this block 2b turns around 
the axis of the shaft 1 without friction on the block 2a.