Rotary wheel set system of a horological movement

Patent metadata

Field	Value
Publication number	US-11886151-B2
Application number	US-202117341536-A
Country	US
Kind code	B2
Filing date	Jun 8, 2021
Priority date	Jun 26, 2020
Publication date	Jan 30, 2024
Grant date	Jan 30, 2024

Abstract

A rotary wheel set system of a horological movement with a rotary wheel set, a first and a second bearing, for a first and a second pivot of the arbor of the rotary wheel set, the wheel set including a mass center in a position of its arbor, the first bearing including an endstone including a main body equipped with a pyramidal cavity configured to receive the first pivot of the arbor of the rotary wheel set, the cavity having at least three faces giving its pyramidal shape, the first pivot being capable of cooperating with the cavity of the endstone to rotate in the cavity, at least one contact zone between the first pivot and a face being generated, the normal at the contact zone or zones forming a contact angle (α h ) relating to the plane perpendicular to the arbor of the pivot, wherein the contact angle (α h ) is less than 45°.

First claim

The invention claimed is:

1. A rotary wheel set system of a horological movement, the system comprising:
a rotary wheel set; and
a first and a second bearing, for a first and a second pivot of an arbor of the rotary wheel set,
wherein the wheel set including a mass centre G in a position of its arbor,
wherein the first bearing includes an endstone comprising a main body equipped with a pyramidal cavity configured to receive the first pivot of the arbor of the rotary wheel set,
wherein the cavity includes at least three faces,
wherein the first pivot is configured to cooperate with the cavity of the endstone in order to be able to rotate in the cavity, at least one contact zone between the first pivot and a face being generated, the normal at the contact zone or zones forming a contact angle α h relating to a plane perpendicular to the arbor of the pivot, and
wherein the contact angle α h is less than 45° , and
wherein the second bearing cooperates with the second pivot to enable the rotary wheel set to rotate about its arbor, the second bearing comprising a second pyramidal cavity including at least three faces, the second pivot being capable of cooperating with the second cavity of a second endstone in order to be able to rotate in the second cavity, at least one second contact zone between the second pivot and a face of the second cavity being generated, the normal of the second contact zone forming a second contact angle α b in relation to the plane perpendicular to the arbor of the second pivot, wherein the contact angles α h , α b of the two pivots and of the two bearings are defined by the following equation,

cot
⁢

α
h

+

cot
⁢

α
b

=

4
⁢
cos
⁢

π
N

≥
2

,

where N is the number of faces of each pyramid.

2. The wheel set system according to claim 1 ,
wherein the pivots have a rounded tip, the rounded tips of the two pivots having identical radii R b , R h ,
wherein μ b is a friction coefficient of the first bearing and μ h is a friction coefficient of the second bearing, and
wherein the contact angles α h , α b are defined by the following equations:

tan
⁢

⁢

α
b

=

BH
_

4
⁢

⁢
cos
⁢

⁢

π
N

⁢

⁢

GH
_

tan
⁢

⁢

α
h

=

BH
_

4
⁢

⁢
cos
⁢

⁢

π
N

⁢

⁢

GB
_

R
h

R
b

=

μ
b

μ
h

⁢

GH
_

GB
_

where N is the number of faces of the two pyramids, BH is a distance between the ends of the two pivots, GH is a distance between the end of the first pivot in contact with the first bearing and the mass centre G of the balance, and GB is a distance between the end of the second pivot in contact with the second bearing and the mass centre G of the balance 2 .

3. The wheel set system according to claim 1 , wherein the first contact angle α h is less than or equal to arctan(½) and the second contact angle α b is greater than or equal to arctan(½).

4. The wheel set system according to claim 1 , further comprising as many contact zones as faces of the pyramidal cavity with one contact zone per face.

5. The wheel set system according to claim 1 , wherein the cavity comprises three or four faces.

6. The wheel set system according to claim 1 , wherein the first pivot has a conical shape.

7. The wheel set system according to claim 1 , wherein the two contact angles α b , α h are equal.

8. The wheel set system according to claim 1 , wherein the end of the pivot is defined by an intersection between the normal at the contact and the arbor of the pivot.

9. The wheel set system according to claim 1 , wherein the pivots have a rounded tip, the rounded tips of the two pivots having identical radii R b , R h .

10. A horological movement comprising a plate and at least one bridge, said plate and/or the bridge including an orifice, wherein the horological movement includes a rotary wheel set system according to claim 1 .

11. The wheel set system according to claim 1 , wherein

cot
⁢

α
h

±

cot

Assignees

• Eta Sa Mft Horlogere Suisse

Inventors

• Helfer Jean-Luc
• Lechot Dominique

Classifications

• G04B31/0087 Primary

  with jewel hole only · CPC title

• G04B31/008

  Jewel bearings (G04B31/04 takes precedence) · CPC title

• G04B31/0082

  with jewel hole and cap jewel (shock damping bearings with jewel hole and cap jewel G04B31/04) · CPC title

• G04B31/02 Primary

  Shock-damping bearings {(shock damping in the case G04B37/052, G04B37/055, G04B37/0418)} · CPC title

• G04B31/04 Primary

  with jewel hole and cap jewel {(jewel bearings with jewel hole and cap jewel G04B31/0082; tools for inserting jewel bearings G04D3/042)} · CPC title