Balance wheel

Abstract

A balance wheel for a horological instrument comprises a substantially annular rim having an enlarged counterweight portion and carrying a body (e.g., coil, magnet). The balance wheel is designed so that the body position is normally offset from the axis of the balance wheel in order that variations in body weight cause a related movement of the balance wheel about the axis. The rotation of the axially supported and initially unpoised balance wheel presents a portion of the counterweight to a stationary tool. The counterweight portion is of a predetermined configuration and the wheel is so designed that the tool removes sufficient material to poise the balance wheel.

I claim: 
     
       1. A balance wheel comprising: a balance body having an axis, a counterweight portion and at least one element subject to weight variations mounted on the other side of said axis from said counterweight portion to cause rotation of the body through an angle when the axis is horizontal and the wheel is not properly poised,   said counterweight portion being tapered in a peripheral direction so that said angle is determined by the amount of dispoise, and also varying in distance from said axis in a predetermined manner to facilitate removal of greater predetermined sections of said counterweight portion for correction of correspondingly .[.lesser.]. .Iadd.greater .Iaddend.amounts of dispoise.   
     
     
       2. The combination according to claim 1, wherein said wheel comprises: an outer rim having said counterweight portion extending inwardly therefrom and having a predetermined peripheral contour, the contour of said counterweight portion varying to reflect conditions of dispoise between a maximum value and a minimum value when the balance wheel is supported at its rotational axis and the location of said counterweight portion being determined from corresponding variations in the angle of dispoise between predetermined limits, and   a spoke extending inwardly from the rim at a location designed to balance the forces about the axis of the balance wheel and having an area designed to balance said forces, said spoke terminating in a mounting receptacle.   
     
     
       3. The combination according to claim 1, wherein said body is substantially annular and said counterweight portion is located on the outer periphery thereof to facilitate posing of said wheel by removal of a portion of said counterweight, and at least one recess therein for purposes of balance compensation and, said element comprises magnet means mounted in a predetermined position on said body.   
     
     
       4. The combination according to claim 1, wherein said balance body comprises: a balance body including an outer rim, a spoke extending inwardly from the body and having a mounting yoke at the other end thereof, and   wherein said element is mounted to the yoke to cause rotation thereof when the wheel is supported at its rotational axis and is not properly poised.   
     
     
       5. A balance body in accordance with claim 4 wherein: the outer rim has ring-like configuration which is discontinuous forming a gap between the opposite ends, and   the yoke includes a main body portion having a base and two arms extending outwardly from the base, said spoke being joined to the yoke at a predetermined distance from the base.