GB2039389A

GB2039389A - Balance-wheel for time-keeping instruments

Info

Publication number: GB2039389A
Application number: GB7944265A
Authority: GB
Original assignee: SCHIEBUHR E
Current assignee: SCHIEBUHR E
Priority date: 1979-01-25
Filing date: 1979-12-21
Publication date: 1980-08-06
Also published as: FR2447571A1; JPS55101884A; DE2902810B1; DE2902810C2

Abstract

A balance-wheel for time-keeping instruments, in which two identical hair springs 1,2 of flat spiral design have their inner and outer ends respectively attached, at points which are diametrically opposite to one another, on the one hand to the staff or balance-wheel arbor 5 and on the other hand to the balance cock 8 and are arranged to lie in two planes parallel to one another and normal to the balance-wheel axis, is characterised in that the hair-springs are coiled in the same sense and are rotationally staggered relative to one another through 180 DEG about the axis of the balance-wheel. The two spiral hair- springs may each be provided with an overcoil 6, 7 and turned outwards in like manner but in opposite axial directions with regard to the balance-wheel arbor. Regulation is preferably effected through a symmetrical two-armed lever 4 seated on the balance-cock 8 and rotatable with regard to the balance- wheel arbor, said lever arms spanning the two spiral hair-springs at the circular regulating ends of the outermost coils. <IMAGE>

Description

SPECIFICATION Balance-wheel for time-keeping instruments The invention relates to a balance-wheel for timekeeping instruments, in which two identical spiral hair-springs of flat spiral design are attached at points at any given time diametrally opposite to one another on the one hand to the staff or balancewheel arbor and on the other hand to the balancewheel cheek in two planes parallel to one another and normal to the balance-wheel axis.

There is known a balance-wheel-like movement regulatorfortime-keeping instruments, in which the arbor of an oscillatory member is connected through respective first and second spiral hair-springs with respective plates. The two identical spiral hairsprings are attached to the balance-wheel arbor and to the balance-wheel cheek in two planes extending normal to the balance-wheel axis and parallel to one another, in such a way that they confront one another when projected and brought together. With such an arrangement of the spiral springs the centre of gravity of the arrangement changes its position on deflection of the balance-wheel from the equilibrium position. Considered in the plane of projection, the centre of gravity is moved to the axis of symmetry of the confrontation.

The object of the invention is to provide a balance-wheel of the kind first-mentioned, in the case of which a change of the centre of gravity can no longer occur on deflection of the balance-wheel.

In accordance with the present invention, I provide a balance-wheel for time-keeping instruments, in which two identical spiral hair-springs of flat spiral design are attached at points at any given time diametrally opposite to one another on the one hand to the staff or balance-wheel arbor and on the other hand to the balance-wheel cheek in two planes parallel to one another and normal to the balancewheel axis, the two spiral hair-springs being coiled in the same sense and being rotationally staggered relative to one another through 1800 about the axis of the balance-wheel.

Through such an arrangement of the spiral hairsprings relative to one another, what is attained is that, apart from a slight deformation of the spiral hair-springs under the influence of the force of gravity, the centre ofgravity of the balance-wheel with the two spiral hair-springs is continually in the axis of the balance-wheel whatever the deflection of same. The consequence of this is that the bearing friction of the balance-wheel is less irregular and, moreover, is also smaller; the accuracy is greater and the working life superior to that of a balancewheel of the known type.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings wherein: Figure lisa diagrammatic plan view of a balancewheel with two spiral hair-springs in accordance with the invention; Figure 2 is a side view of the balance-wheel system according to Figure 1, and Figure 3 shows the structural appearance of the balance-wheel system according to Figure 2.

In the drawings the reference numerals 1 and 2 each denote a breguet hair-spring, the reference numeral 3 denotes the rim of the balance-wheel, the reference numeral 4 denotes a regulating lever with arms, the reference numeral 5 denotes the balancewheel arbor, the reference numeral 6 denotes the overcoil for the spiral hair-spring 1, the reference numeral 7 denotes the overcoil for the spiral hairspring 2, and the reference numerals 8 and 9 denote plates for the bearing of the balance-wheel arbor and of the regulating lever.

As can be seen in the drawings, the two spiral hair-springs 1 and 2 are arranged in the same sense of winding rotationally staggered relative to one anotherthrough 180 about the balance-wheel axis.

The projection of one flat spiral hair-spring in a plane normal to the balance-wheel axis proceeds away from that of the other by rotation through a straight angle, namely by 1800, and conversely.

The two spiral hair-springs 1 and 2 are each provided with an overcoil 6 and 7, respectively, being turned outwards in like manner in opposite directions with regard to the balance-wheeld axis.

The regulation may be effected through a symmetrical two-armd lever 4 seated on one balance-wheele cheek in a plane normal to the balance-wheel axis and rotatable with regard to the balance-wheel arbor, which lever spans with associated arms the two spiral hair-springs at the circular regulating ends of the outermost coils.

1. A balance-wheel fortime-keeping instruments, in which two identical spiral hair-springs of flat spiral design are attached at points at any given time diametrally opposite to one another on the one hand to the staff or balance-wheel arbor and on the other hand to the balance-wheel cheek in two planes parallel to one another and normal to the balancewheel axis, the two spiral hair-springs being coiled in the same sense and being rotationally staggered relative to one another through 1800 about the axis of the balance-wheel.

2. A balance-wheel according to claim 1, in which the two spiral hair-springs are each provided with an overcoil and are turned outwards in like manner in opposite directions with regard to the balance-wheel arbor.

3. A balance-wheel according to claim 1 or 2, in which the regulation is effected through a symmetrical two-armed lever seated on the balance-wheel cheek in a plane normal to the balance-wheel arbor and rotatable with regard to the balance-wheel arbor, which lever spans with associated arms the two spiral hair-springs at the circular regulating ends of the outermost coils.

4. A balance-wheel fortime-keeping instruments substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Balance-wheel for time-keeping instruments The invention relates to a balance-wheel for timekeeping instruments, in which two identical spiral hair-springs of flat spiral design are attached at points at any given time diametrally opposite to one another on the one hand to the staff or balancewheel arbor and on the other hand to the balancewheel cheek in two planes parallel to one another and normal to the balance-wheel axis. There is known a balance-wheel-like movement regulatorfortime-keeping instruments, in which the arbor of an oscillatory member is connected through respective first and second spiral hair-springs with respective plates. The two identical spiral hairsprings are attached to the balance-wheel arbor and to the balance-wheel cheek in two planes extending normal to the balance-wheel axis and parallel to one another, in such a way that they confront one another when projected and brought together. With such an arrangement of the spiral springs the centre of gravity of the arrangement changes its position on deflection of the balance-wheel from the equilibrium position. Considered in the plane of projection, the centre of gravity is moved to the axis of symmetry of the confrontation. The object of the invention is to provide a balance-wheel of the kind first-mentioned, in the case of which a change of the centre of gravity can no longer occur on deflection of the balance-wheel. In accordance with the present invention, I provide a balance-wheel for time-keeping instruments, in which two identical spiral hair-springs of flat spiral design are attached at points at any given time diametrally opposite to one another on the one hand to the staff or balance-wheel arbor and on the other hand to the balance-wheel cheek in two planes parallel to one another and normal to the balancewheel axis, the two spiral hair-springs being coiled in the same sense and being rotationally staggered relative to one another through 1800 about the axis of the balance-wheel. Through such an arrangement of the spiral hairsprings relative to one another, what is attained is that, apart from a slight deformation of the spiral hair-springs under the influence of the force of gravity, the centre ofgravity of the balance-wheel with the two spiral hair-springs is continually in the axis of the balance-wheel whatever the deflection of same. The consequence of this is that the bearing friction of the balance-wheel is less irregular and, moreover, is also smaller; the accuracy is greater and the working life superior to that of a balancewheel of the known type. An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings wherein: Figure lisa diagrammatic plan view of a balancewheel with two spiral hair-springs in accordance with the invention; Figure 2 is a side view of the balance-wheel system according to Figure 1, and Figure 3 shows the structural appearance of the balance-wheel system according to Figure 2. In the drawings the reference numerals 1 and 2 each denote a breguet hair-spring, the reference numeral 3 denotes the rim of the balance-wheel, the reference numeral 4 denotes a regulating lever with arms, the reference numeral 5 denotes the balancewheel arbor, the reference numeral 6 denotes the overcoil for the spiral hair-spring 1, the reference numeral 7 denotes the overcoil for the spiral hairspring 2, and the reference numerals 8 and 9 denote plates for the bearing of the balance-wheel arbor and of the regulating lever. As can be seen in the drawings, the two spiral hair-springs 1 and 2 are arranged in the same sense of winding rotationally staggered relative to one anotherthrough 180 about the balance-wheel axis. The projection of one flat spiral hair-spring in a plane normal to the balance-wheel axis proceeds away from that of the other by rotation through a straight angle, namely by 1800, and conversely. The two spiral hair-springs 1 and 2 are each provided with an overcoil 6 and 7, respectively, being turned outwards in like manner in opposite directions with regard to the balance-wheeld axis. The regulation may be effected through a symmetrical two-armd lever 4 seated on one balance-wheele cheek in a plane normal to the balance-wheel axis and rotatable with regard to the balance-wheel arbor, which lever spans with associated arms the two spiral hair-springs at the circular regulating ends of the outermost coils. CLAIMS