Balance-hairspring oscillator for a timepiece

Patent metadata

Field	Value
Publication number	US-11249440-B2
Application number	US-201716078952-A
Country	US
Kind code	B2
Filing date	Mar 15, 2017
Priority date	Mar 23, 2016
Publication date	Feb 15, 2022
Grant date	Feb 15, 2022

Abstract

In an oscillator for a timepiece including a balance and a hairspring, the balance lacks equilibrium, such that: the curves for running of the oscillator owing to weight of the hairspring as a function of the oscillation amplitude of the balance in at least four vertical positions of the oscillator spaced by 90° each pass through 0 at an oscillation amplitude of the balance between 200° and 240°; and between oscillation amplitudes of 150° and 280°, curves representing the running of the oscillator owing to lack of equilibrium in the balance as a function of the oscillation amplitude in the vertical positions each has an average slope of opposite sign to the average slope of the corresponding curve among the curves representing the running of the oscillator owing to the weight of the hairspring. A reduction in the running discrepancies between the vertical positions can thus be achieved.

First claim

The invention claimed is:

1. An oscillator for a timepiece, comprising:
a balance ( 1 ); and
a hairspring ( 3 ; 3 ′), the balance having a lack of equilibrium,
wherein the lack of equilibrium in the balance and the geometry of the hairspring are such that
a) first curves (S 1 -S 4 ; S 1 ′-S 4 ′) representing the running of the oscillator owing to the weight of the hairspring as a function of the oscillation amplitude of the balance in at least four vertical positions of the oscillator spaced apart by 90° each pass through a value zero of running at an oscillation amplitude of the balance between 200° and 240°; and
b) between the oscillation amplitude of 150° and the oscillation amplitude of 280°, second curves (B 1 -B 4 ; B 1 ′-B 4 ′) representing the running of the oscillator owing to the lack of equilibrium in the balance as a function of the oscillation amplitude of the balance in said vertical positions of the oscillator each have an average slope of opposite sign to the average slope of a corresponding curve among said first curves (S 1 -S 4 ; S 1 ′-S 4 ′) representing the running of the oscillator owing to the weight of the hairspring,
wherein said first curves are obtained by the following formula:

μ
⁡

(

θ
0

)

=

-
8

⁢
6
⁢
4
⁢
0
⁢

0
.

M
s

.
L

E
.
I

.
g
.

1

2
.
π
.

θ
0
2

⁢

∫
0

2.
⁢
π

⁢

δ
⁢

y
g

⁡

(

θ
⁡

(
φ
)

)

δ
⁢
θ

.

θ
⁡

(
φ
)

.
d

⁢

⁢
φ

and said second curves are obtained by the following formula:

μ
⁡

(

θ
0

)

=

8
⁢
6
⁢
4
⁢
0
⁢

0
.

M
b

.
g
.
d

J
b

.

ω
0
2

.

J
1

⁡

(

θ
0

)

θ
0

.

cos
⁡

(

ϕ
+
β

)

where μ is the running, M s is the mass of the hairspring, L is the length of the hairspring, E is the Young's modulus of the hairspring, I is the second moment of area of the hairspring, g is the gravitational constant, θ is the elongation of the balance with respect to its equilibrium position, θ 0 is the amplitude of the balance with respect to its equilibrium position, φ is the phase, y g is the ordinate of the center of gravity of the hairspring in a coordinate system (O, x, y) where the y axis is opposite to gravity, M b is the mass of the balance, d is the radial position of the center of gravity of the balance, J b is the moment of inertia of the balance, ω o is the natural angular frequency of the oscillator, J 1 is the Bessel function of order 1 , β is the angular position of the center of gravity of the balance with respect to an impulse pin of the balance and ϕ is the angular position of the impulse pin with respect to the direction of gravity.

2. The oscillator as claimed in claim 1 , wherein the geometry of the hairspring is such that said first curves (S 1 -S 4 ; S 1 ′-S 4 ′) representing the running of the oscillator owing to the weight of the hairspring each pass through the value zero at an oscillation amplitude of the balance between 210° a

Assignees

• Patek Philippe Sa Geneve

Inventors

• Bucaille Jean-Luc

Classifications

• G04D7/08 Primary

  for balance wheels · CPC title

• G04D7/10 Primary

  for hairsprings {of balances} · CPC title

• G04B17/066

  Manufacture of the spiral spring (locking of the spiral spring by the regulating lever G04B18/026; spiral spring with temperature compensation G04B17/227; fixation of the spiral spring on the collet G04B17/32; mainspring G04B1/14) · CPC title

• G04B17/28

  for the effect of imbalance of the weights, e.g. tourbillon · CPC title

• G04B17/06 Primary

  Oscillators with hairsprings, e.g. balance {(electrically driven balances G04C3/04; contacts actuated by a balance G04C13/065)} · CPC title