Mechanical timepiece movement with a lever escapement

Patent metadata

Field	Value
Publication number	US-10222746-B2
Application number	US-201615373514-A
Country	US
Kind code	B2
Filing date	Dec 9, 2016
Priority date	Dec 23, 2015
Publication date	Mar 5, 2019
Grant date	Mar 5, 2019

Abstract

The mechanical timepiece movement includes an escapement having a pallet-lever arranged to move alternately into abutment with two banking elements in locking periods. The pallet-lever carries at least a first permanent magnet and the timepiece movement further includes a first element and a second element of high magnetic permeability and a second magnet and a third magnet respectively integral with first and second elements of high magnetic permeability and each arranged on an opposite side to a first magnet relative to the respective elements of high magnetic permeability. This magnetic system generates, in a first part of a first half vibration of any vibration of the pallet-lever, an overall force of magnetic attraction, defining a magnetic draw additional to the mechanical draw generated by the escape wheel, and, in a second part of this first half vibration, an overall force of magnetic repulsion.

First claim

What is claimed is:

1. A mechanical timepiece movement, comprising:
a balance provided with a pivot shaft;
an escapement associated with said balance, said escapement comprising a pallet-lever provided with a fork;
an impulse pin integral with the balance and cooperating with the fork to allow the latter to provide the balance with impulses maintaining the oscillation thereof by a drive force applied to an escape wheel, which is coupled to the pallet-lever; and
two banking elements preventing rotation of the pallet-lever, which define two locking positions of the pallet-lever and between said two locking positions an angular distance for the pallet-lever, said pallet-lever being arranged to move alternately into abutment with the two banking elements in locking periods occurring between said impulses provided to the balance;
wherein the pallet-lever carries at least one permanent magnet which has an axis of magnetisation oriented substantially tangentially to a circular axis of displacement of said at least one permanent magnet, when the pallet-lever is subjected to said movements of said movements of rotation;
wherein the timepiece movement comprises a first element of high magnetic permeability and a second element of high magnetic permeability respectively arranged on either side of said at least one permanent magnet so as to be substantially aligned on the circular axis of displacement, the first element of high magnetic permeability and the second element of high magnetic permeability and the two banking elements having substantially the same plane of symmetry;
wherein the timepiece movement further includes a second permanent magnet integral with the first element of high magnetic permeability and a third permanent magnet integral with the second element of high magnetic permeability, the second permanent magnet being arranged further away from said at least one permanent magnet than the first element of high magnetic permeability, and the third permanent magnet being arranged further away from said at least one permanent magnet than the second element of high magnetic permeability;
wherein said at least one permanent magnet and a first assembly formed of the second permanent magnet and the first element of high magnetic permeability are arranged to generate, between said at least one permanent magnet and said first assembly, a force of magnetic attraction on a first section of said angular distance and a force of magnetic repulsion on a second section of said angular distance, the second section corresponding to a distance of separation between said at least one permanent magnet and said first assembly that is greater than the distance of separation corresponding to the first section, and
wherein said at least one permanent magnet and a second assembly formed of the third permanent magnet and the second element of high magnetic permeability are arranged to generate, between said at least one permanent magnet and said second assembly, a force of magnetic attraction on a third section of said angular distance and a force of magnetic repulsion on a fourth section of said angular distance, the fourth section corresponding to a distance of separation between said at least one permanent magnet and said second assembly that is greater than the distance of separation corresponding to the third section.

2. The timepiece mechanism according to claim 1 , wherein the first element of high magnetic permeability has a central axis that is substantially coincident with an axis of magnetisation of the second permeant magnet, and the second element of high magnetic permeability has a central axis that is substantially coincident with an axis of magnetisation of the third permeant magnet, said central axis of the first element of high magnetic permeability and the central axis of the second element of high magnetic permeability being substantially tangent to the circular axis of displacement.

3. The timepiece mechanism according to claim 1 , wherein said at least one permanent magnet carried by the pallet-lever consists only of a first permanent magnet that has an opposite polarity to a polarity of the second permanent magnet and a polarity of the third permanent magnet in projection along the circular axis of displacement.

4. The timepiece mechanism according to claim 1 , wherein said at least one permanent magnet carried by the pallet-lever is formed by a first permanent magnet and a fourth permanent magnet, said fourth permanent magnet also having an axis of magnetisation substantially oriented tangentially to the circular axis of displacement, said first permanent magnet and said fourth permanent magnet being respectively arranged facing the first element of high magnetic permeability and the second element of high magnetic permeability along the circular axis of displacement; and wherein, in projection along the circular axis of displacement, the first permanent magnet has an opposite polarity to a polarity of the second permanent magnet, and the fourth permanent magnet has an opposite polarity to a polarity of the third permanent magnet.

5. The timepiece mechanism according to claim 1 , wherein the first element of high magnetic permeability and the second element of high magnetic permeability are respectively mounted on the two banking elements.

6. The timepiece mechanism according to claim 1 , wherein the first element of high magnetic permeability and the second element of high magnetic permeability also form the two banking elements so that the first element of high magnetic permeability and the second element of high magnetic permeability are respectively coincident with the two banking elements, and wherein said first element of high magnetic permeability and the second element of high magnetic permeability are of spherical shape.

7. The timepiece mechanism according to claim 1 , wherein said first assembly and said second assembly and said at least one permanent magnet are arranged such that an overall force of magnetic attraction, exerted by said first assembly and said second assembly on said at least one permanent magnet, is substantially cancelled out when a centre of said at least one permanent magnet is substantially in said plane of symmetry, and
wherein the centre of said at least one permanent magnet, starting from said plane of symmetry along the circular axis of displacement in the direction of said first assembly or said second assembly, defines, in a first angular range, a force of magnetic repulsion relative to said first assembly or said second assembly and then, in a second angular range moving closer to said first assembly or said second assembly, a force of magnetic attraction relative to said first assembly or said second assembly.

8. The timepiece mechanism according to claim 7 , wherein the pallet-lever is provided with a guard pin cooperating with a lateral surface of said pivot shaft or of a roller mounted around the latter.

Assignees

• Montres Breguet Sa

Inventors

• Sarchi Davide
• Legeret Benoit
• Junod Benoit
• Karapatis Polychronis Nakis

Classifications

• G04C5/005

  Magnetic or electromagnetic means · CPC title

• G04B15/14 Primary

  Component parts or constructional details, e.g. construction of the lever or the escape wheel {(assembly and manufacture of the spring G04B1/145; assembly and manufacture of components, e.g. pinions, spindles G04B13/02; lubrication of clockwork bearings G04B31/008; oils for clockwork bearings in general G04B31/08)} · CPC title

• G04B15/12

  Adjusting (tools therefor G04D1/02); Restricting the amplitude of the lever or the like {(adjusting the gear train G04B35/00)} · CPC title

• G04B15/08

  Lever escapements · CPC title