초록 ▼

The application discloses a method of making a balance spring (100) from continuous fibers or ceramic by winding them around a cylindrical former (90), interspaced with a releasing agent (110). Also disclosed is a method of making a balance spring, preferably of a ceramic material (60), by applying

The application discloses a method of making a balance spring (100) from continuous fibers or ceramic by winding them around a cylindrical former (90), interspaced with a releasing agent (110). Also disclosed is a method of making a balance spring, preferably of a ceramic material (60), by applying it to a rotating former (70) mandrel or plate and subsequently heat treating. Balance wheels (30) having a moment of inertia which decreases with a rise in temperature due to a special arrangement of components (8, 9, 10) having different coefficients of thermal expansion are also disclosed. A mechanical oscillator system comprising a non-magnetic ceramic or continuous fiber balance spring (50) and a non-magnetic balance wheel (30) formed of a material having a coefficient of thermal expansion of less than 6×10−6K−1 and having a plurality of non-magnetic poising or timing appendages (5) is also disclosed.

대표청구항 ▼

The invention claimed is: 1. A thermally compensating non-magnetic balance wheel for use in conjunction with a thermally stable non-magnetic balance spring in a mechanical oscillator system in a horological or other precision instrument, the balance wheel comprising: components of two different non

The invention claimed is: 1. A thermally compensating non-magnetic balance wheel for use in conjunction with a thermally stable non-magnetic balance spring in a mechanical oscillator system in a horological or other precision instrument, the balance wheel comprising: components of two different non-magnetic materials having different thermal expansion coefficients, the components including a balance arm attached to a balance rim, the balance arm having a thermal expansion coefficient that is less than 6×10−6K−1 and the balance rim having a thermal expansion coefficient different from the thermal expansion coefficient of the balance arm, the components being arranged to give equipoise to the balance wheel and to cause a decrease in the moment of inertia of the balance wheel with an increase in temperature, wherein the decrease in the moment of inertia is arranged to compensate for changes in the elasticity of the balance spring caused by the increase in temperature. 2. A balance wheel according to claim 1, wherein the balance arm has one or more cross members and the balance rim is attached to or integral with said cross members. 3. A balance wheel according to claim 2, wherein the balance rim and cross member(s) are formed of a first material having a first coefficient of thermal expansion and the balance wheel further comprises two concave segments inside said rim, formed of a different material to said rim having a second coefficient of thermal expansion greater than said first coefficient of thermal expansion. 4. A balance wheel according to claim 2, wherein the balance rim is formed of a first material having a first coefficient of thermal expansion and two or more members formed of a second material having a second coefficient of thermal expansion greater than said first material are attached to said rim and extend inwardly therefrom. 5. A balance wheel according to claim 2, wherein the cross member(s) is of a first material having a first coefficient of thermal expansion and the rim is of a second material having a second coefficient of thermal expansion less than the first coefficient of thermal expansion, such that the increase in temperature causes an increase in the cross member(s) length and radially inward deflection of the rim to cause the decrease in the moment of inertia of the balance wheel. 6. A balance wheel according to claim 5, wherein there are at least two appendages to the rim in the form of non-magnetically sensitive timing weights. 7. A balance wheel according to claim 5, wherein said second coefficient of thermal expansion is negative. 8. A balance wheel according to claim 5, wherein there are one or more appendages arranged on the cross member(s), said appendage(s) comprising a stem and an eccentric head on the stem, the stem being rotatably mounted in an aperture of the balance wheel such that it is rotatable about an axis parallel to the axis of rotation of the balance wheel, whereby the moment of inertia of the balance wheel can be fine tuned by turning of the eccentric head. 9. A balance wheel according to claim 2, wherein the cross member(s) is of a first material having a first coefficient of thermal expansion and the rim comprises concave segments of a second material having a second coefficient of thermal expansion greater than said first coefficient of thermal expansion. 10. A balance wheel according to claim 9, wherein the second coefficient of thermal expansion is positive and greater than said first coefficient of thermal expansion, such that said concave segments are arranged to extend further radially inward with the increase in temperature to cause the decrease in the moment of inertia of the balance wheel. 11. A balance wheel according to claim 10, wherein there are a plurality of appendages to the concave segments in the form of non-magnetically sensitive timing weights. 12. A balance wheel according to claim 10, wherein said first coefficient of thermal expansion is negative, such that the cross member length(s) decreases with the increase in temperature to cause the decrease in the moment of inertia of the balance wheel. 13. A balance wheel assembly comprising: a thermally compensating non-magnetic balance wheel for use in conjunction with a thermally stable non-magnetic balance spring in a mechanical oscillator system in a horological or other precision instrument, the balance wheel including components of two different non-magnetic materials having different coefficients of thermal expansion, the components including a balance arm attached to a balance rim, the balance arm having a thermal expansion coefficient that is less than 6×10−6K−1 and the balance rim having a thermal expansion coefficient different from the thermal expansion coefficient of the balance arm, the components being arranged to give equipoise to the balance wheel and to cause a decrease in the moment of inertia of the balance wheel with an increase in temperature, wherein the decrease in the moment of inertia is arranged to compensate for changes in the elasticity of the balance spring caused by the increase in temperature; and a balance staff formed integrally with the balance wheel. 14. A balance wheel assembly according to claim 13, wherein the balance wheel and balance staff are formed of a ceramic material. 15. A balance wheel assembly according to claim 13, wherein the balance staff is integrally formed with one or more cross members which are arranged to support the balance rim. 16. A method of forming a balance wheel assembly, the balance wheel assembly comprising: a thermally compensating non-magnetic balance wheel for use in conjunction with a thermally stable non-magnetic balance spring in a mechanical oscillator system in a horological or other precision instrument, the balance wheel including components of two different non-magnetic materials having different materials having different coefficients of thermal expansion, the components including a balance arm attached to a balance rim, the balance arm having a thermal expansion coefficient that is less than 6×10−6K−1 and the balance rim having a thermal expansion coefficient different from the thermal expansion coefficient of the balance arm, the components being arranged to give equipoise to the balance wheel and to cause a decrease in the moment of inertia of the balance wheel with an increase in temperature, wherein the decrease in the moment of inertia is arranged to compensate for changes in the elasticity of the balance spring caused by the increase in temperature; and a balance staff formed integrally with the balance wheel; the method comprising attaching the balance staff and balance wheel together when they are in their green state and using a bonding or heat treatment process to secure them together.