US3465514A

US3465514A - Mainspring slipping ring for a self-winding timepiece

Info

Publication number: US3465514A
Application number: US694983A
Authority: US
Inventors: Jean Haueter
Original assignee: VIMETAL
Current assignee: VIMETAL
Priority date: 1967-01-24
Filing date: 1968-01-02
Publication date: 1969-09-09
Anticipated expiration: 1986-09-09
Also published as: DE1673717B2; FR1552454A; CH111867A4; DE1673717A1; CH593507B5

Description

Sept. 9, 1969 J. H A'UETER 3,465,514

MAINSPRING SLIPPING RING FOR A SELF-WINDING TIMEPIECE Filed Jan. 2, 1968 //YV/WOR Jean HAl/[TER Alforney United States Patent O Int. 01. G04b 1/16 U.S. Cl. 58-86 2 Claims ABSTRACT OF THE DISCLOSURE A mainspring for a self-winding timepiece of the type including a barrel comprising, a blade, the blade being extended at its outer extremity to provide an end portion of increased thickness, said end portion being integral with the blade and adapted to bear against the inner wall of the barrel in the manner of a slipping ring.

BACKGROUND OF THE INVENTION Field of the invention Mainsprings for self-winding timepieces.

Description of the prior art In self-Winding watches of the prior art, the outer extremity of the mainspring is generally not rigidly secured to the barrel, as in the conventional watches, but is connected to the barrel through the intermediary of a supplementary elastic blade, called a slipping spring, arranged in such a manner as to bear elastically against the inner wall of the barrel. This slipping spring does not move relatively to the barrel so long as the winding of the mainspring is lower than a determined value. When this winding value of the mainspring is reached, the slipping spring slips on the inner wall of the barrel, thereby preventing any overwinding of the mainspring even when the automatic Winding continues to operate.

The slipping spring is secured to the extremity of the outer coils of the mainspring by rivets or, more generally, by points of electric welding. The assembling and the securing of the slipping spring to the mainspring are delicate, due to the fact that the longitudinal axes of the mainspring and of the slipping spring must be in very precise alignment. Moreover, the rivets or the welding break away, thereby rendering the watch unusable.

SUMMARY OF THE INVENTION A primary object of the present invention is to remedy the drawbacks of the prior art.

The mainspring according to the invention is characterized by the fact that its blade is extended, at its outer extremity, by an integral portion of greater thickness, intended to be applied against the inner wall of the barrel in which the mainspring is located and to act as a slipping spring.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a plan view of a barrel and mainspring for a self-winding watch, and embodying one form of the invention;

FIG. 2 is an enlarged, fragmentary, broken perspective view of the outer extremity of the mainspring contained in the barrel represented in FIG. 1, and

FIG. 3 is an enlarged, fragmentary, broken plan view of a modification of a mainspring embodying the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The barrel represented in FIG. 1 is designated by 1aand contains a mainspring 2, the inner coil of which is hooked to a core 3 and the outer extremity of which is extended by 3,465,514 Patented Sept. 9, 1969 a portion 2a of greater thickness than that of the main body portion or blade of the mainspring, but formed integrally therewith.

When the spring is not mounted in the barrel, the portion 2a is reversed with respect to the winding direction of the mainspring, so that once the mainspring is in place in the barrel, it exerts on the inner wall thereof a pressure which depends from its thickness, the end portion 2a of the spring thus acting like a slipping spring.

The portion 2a of the spring is produced during the rolling of the spring, for instance by varying the distance between the two rollers of the rolling mill during the operation, by means of a servo mechanism setting this distance according to the advance of the rolled strap.

The effect of this process is that the end portion 2aof the mainspring, constituting the slipping spring, is of slightly less height than the blade of the spring.

In the example represented in FIGS. 1 and 2, the thickness of the portion 2a of the mainspring is substantially double that of the main body or blade of the spring; in practise, the thickness of end portion 2a will be about 1.3 to 2 times that of the blade. Of course, this thickness is variable as desired. In the case of the spring of FIGS. 1 and 2, the thickness of the portion 2a is constant throughout its whole length. As seen in plan, this portion has substantially the shape of a rectangle. However, this thickness could vary; for example, the thickness could increase from the free extremity of the portion 2a towards the middle part thereof, and then decrease from the middle part to the inner extremity where it connects to the main body portion or blade of the mainspring. In such an embodiment, the plan view of the end portion of the mainspring would have the general shape of a rhomb; such an arrangement would reinforce, in the middle portion of the slipping spring, the force exerted by the slipping spring on the wall of the barrel.

It is to be noted that, as soon as a rolling mill is arranged in such a way as to produce end portions of variable thickness, it is possible to use the mill for obtaining springs, the blades of which are also of variable thickness. Such a construction is shown for the mainspring 4 of FIG. 3, which is provided with an end portion 4a of greater height, constituting a slipping spring, the blade of which is itself of a thickness which decreases from the inner extremity of the mainspring towards its outer extremity.

I claim:

1. A mainspring for a self-winding timepiece of the type including a barrel comprising, a blade, the blade being extended at its outer extremity by an integral end portion of increased thickness, the thickness being constant throughout its length and being between 1.3 and 2 times the thickness of the blade, the thickened end portion being adapted to bear against the inner wall of the barrel in which the spring is disposed for functioning as a slipping ring.

2. A mainspring according to claim 1, characterized by the fact that the thickness of its end portion acting as a slipping spring is substantially the same throughout the whole length of the end portion.

References Cited UNITED STATES PATENTS 43,464 7/1864 Philippe 58-86 FOREIGN PATENTS 1,496,479 9/1967 France.

1,828 7/1863 Great Britain.

RICHARD B. WILKINSON, Primary Examiner GEORGE H. MILLER, JR., Assistant Examiner