CH506824A - Device producing friction on a rotating part of a clockwork movement - Google Patents

Description

  

  
 



  Device producing friction on a rotating part of a clockwork movement
 The present invention relates to a device producing friction on a rotating element of a clockwork movement, comprising an annular spring coaxial with said element and which acts on said rotating element to bias it axially and produce said friction.



   This device is characterized by the fact that said rotary element has an annular rib, coaxial with its axis of rotation, on which said spring bears.



   It follows from this arrangement that the torque transmitted is practically constant, without fine adjustment operations being necessary for this purpose.



   Indeed, if the bearing surface is flat, within the limits of ordinary manufacturing tolerances, it is difficult to determine exactly where the friction occurs, that is, at what distance from the center, so that the couple remains undetermined; in the present construction, on the contrary, the distance from the point of application of the force to the center of rotation of the part is perfectly determined.



   It should be noted that the establishment of friction on an annular bearing surface is known per se and that it is applied in so-called Roskopf watches for the adjustment of the timer return on the barrel cover. It is not then a question of a brake, but of a coupling.



   The drawing represents, by way of example, an embodiment of the object of the invention and a variant.



   Fig. 1 is a partial axial section of a chronograph mobile.



   Fig. 2 is a plan view of a detail.



   Fig. 3 is a perspective view of a detail of a variant.



   The chronograph mobile shown in FIG. 1 comprises a chronograph wheel 1 carried by a shaft 2, of which it is integral, pivoted in a bearing 3 of a bridge 4 of the frame of the movement, and which freely crosses a bridge 5 of this frame to be supported, at its end opposite, not shown, in the movement plate, also not shown.



   The shaft 2 of the chronograph wheel 1 carries a drive finger 6 intended to actuate, once per revolution, a minute counter.



   This finger 6 is axially biased by a spring 7 creating, on the shaft 2, a braking torque intended to prevent the rebating of the chronograph hand carried by the shaft 2.



   This spring 7 comprises an annular part 7a, coaxial with the shaft ', resting on the finger 6, and two radial arms 7b, diametrically opposed, the ends of which are pierced with holes 8 traversed, with a slight bead, by pins 9 engaged in holes 10 of the bridge 5. These pegs 9 are within reach and thus exert an axial force on the arms 7b so as to place the spring under tension and to apply it against the finger 6.

 

   Thus, the resultant of all the forces exerted by the spring 7 on the finger 6 coincides with the geometric axis of the shaft 2.



   It should be noted that the face 11 of the finger 6 against which the annular part 7a of the spring 7 bears has a recess coaxial with the shaft 2, leaving an annular rib 6a on which the spring 7 acts.



   Alternatively (fig. 3), the ends 12a of the spring, designated by 12, are bent at right angles and have their edges 13 concurrent. These ends 12a are intended to be engaged, with a slight bend, directly into the holes 10 of the bridge 5. This simplified construction thus does not require dowels 9.

 

Claims (1)

CLAIM Device producing friction on a rotating element of a clockwork movement, comprising an annular spring coaxial with said element and which acts on the latter to urge it axially and produce said friction, characterized in that said rotating element has an annular rib, coaxial with its axis of rotation, on which the said spring bears.