Abstract:
In this reverser mechanism the winding wheel is assembled on a common axis with two ratchet wheels each assigned to one of the pivoting direction of the oscillating mass. 
     The winding wheel is pierced by rivets which bear respectively a pawl and a spring. The spring which is thus mounted on a pivot means of a pawl cooperating with one of the ratchet wheels loads the pawl which cooperates with the other ratchet wheel. 
     The mechanism is for use with timepieces having automatic winding of the mainspring.

Description:
TECHNICAL FIELD 
     This invention concerns automatic winding arrangements for timepieces by means of an oscillating mass. 
     More precisely, the invention concerns a reverser mechanism for such an automatic winding arrangement. 
     BACKGROUND OF THE INVENTION 
     In standard arrangements, the automatic winding arrangement for a timepiece is assured by an assembly comprising a pivoting oscillating mass which is coupled to the barrel of the main spring through a reverser mechanism in order that the mass deliver kinetic energy for winding the spring regardless of the direction of rotation sense of said mass. 
     Among the most widespread types of reverser mechanisms may be considered those which for each direction of rotation of the oscillating mass comprises a ratchet wheel and a pawl loaded by a spring. The pawls and their associated springs are carried by a common winding wheel which is alternately coupled to the reducer winding gear train through respective pawls acting on the ratchet wheels. 
     Such an arrangement is described in Swiss Pat. No. 344.370. In this case, the winding wheel bears a pawl on each of its faces while the ratchet wheels are mounted on either side of this winding wheel on a common pivot axis. The pawls are hinged on the winding wheel by means of studs fixed in the latter. This patent however does not specify how the springs loading the pawls are arranged on the winding wheel. 
     In another known mechanism described in Swiss Pat. No. 348.922 there is provided a pawl bearing plate associated with a mounting ring coaxial with the plate but spaced apart from the latter. This pawl is mounted hinged on a pivot secured between the plate and the ring and cooperates with a spring anchored in the plate by means of a special stud provided for such anchoring. 
     The purpose of the present invention is to provide a reverser mechanism of the general type suggested hereinabove having a simplified construction so as to render the assembly thereof as simple as possible. 
     SUMMARY OF THE INVENTION 
     The invention thus has as principal object a reverser mechanism for automatic winding of a timepiece by an oscillating mass including a winding wheel coaxially mounted with two ratchet wheels arranged on either face of said winding wheel which bears on each of its faces at least one pawl loaded by a spring and cooperating respectively with one of the ratchet wheels, the assembly thus formed being inserted between the kinematic chain interposed between the oscillating mass and the mainspring barrel of the timepiece, the pawls assigned to the transmission of the rotation of said mass being articulately mounted respectively on pivot means fixed to said winding wheel, the pivot means being the pawl assigned to one of the directions of rotation of the mass serving at the same time as anchoring means for the spring which loads the pawl assigned to transmit the other direction of rotation of said mass. 
     There is thus obtained a reverser mechanism in which each pawl is commonly mounted with a spring which loads the other pawl on a single and common pivot means. There results therefrom not only a reduction in size but likewise a considerable simplification of the assembly. 
     The invention will be better understood from reading the description to follow given solely by way of example and having reference to the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-section and exterior view of a reverser mechanism according to the invention; 
     FIG. 2 is a cross-section view to a larger scale of the winding wheel and the associated elements incorporated in the mechanism according to the invention; 
     FIG. 3 is a plan view of the winding wheel showing the mounting of the pawls and the pawl springs; 
     FIG. 4 is a plan view of one of the rivets employed for fastening a pawl and spring onto the winding wheel; 
     FIG. 5 is a side view of such rivet; 
     FIG. 6 is a partial view of the winding wheel without the elements which it bears and 
     FIG. 7 is a schematic drawing illustrating the operation of the reverser mechanism according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In referring to the drawings, it is seen that the winding wheel 1 of the reverser mechanism according to the invention includes a plate 1a and a bushing 1b which is freely engaged on a pivot axis 2. This latter is mounted for rotation between a bottom plate 3a and a bridge 3b of the timepiece. The plate 1a of the winding wheel 1 includes a crown 1c which meshes with the pinion 4 fixed in rotation to the oscillating mass 5. 
     Axis 2 forms a wheel set with a first ratchet wheel 6 and a transmission wheel 7 meshing with a wheel set 8 of a speed reducer train leading to the barrel (not shown) of the main spring of the timepiece in conformity with the arrangement well known to those skilled in the art. 
     A second ratchet wheel 9 arranged against the face of the plate 1a of the winding wheel 1 opposite to the first ratchet wheel 6 is wedged onto a transmission pinion 10 mounted for free rotation around the bushing 1b of the winding wheel 1. 
     Pinion 10 is in mesh with an intermediate wheel 11 meshing likewise with the wheel set 8 of the speed reducer train. It is to be noted that the cross-section of FIG. 1 corresponds to the broken line I--I shown on FIG. 7. 
     FIG. 6 shows that the plate 1a of winding wheel 1 is pierced with holes 12 situated respectively at 3, 6, 9 and 12 o&#39;clock (FIG. 3), each hole being bounded by two opposed rectilinear edge portions 12a joined by two curved edge portions 12b. 
     Each of these holes 12 receives a rivet 13 serving for the mounting of the winding wheel 1 of an assembly formed respectively by pawls 14a to 14d and springs 15a to 15d. 
     Each rivet includes a stem 16 (FIGS. 4 and 5) provided at one of its ends with a flange 17, a peripheral segment of which is cut off and which thus provides a rectilinear edge 18. 
     A cylindrical portion of small height 19 on stem 16 situated proximate the flange 17 serves for the articulation of pawls 14a to 14d mounted on the rivet 13 under consideration. 
     The remainder of stem 16 exhibits two diametrally opposed flats 20 adjusted to the rectilinear edges 12a of holes 12 of the winding wheel 1. 
     It is seen that the embodiment described each ratchet wheel 6 and 9 cooperates with two respective pawls 14a  14b and 14c, 14d to which are associated springs 15c, 15d and 15a, 15b respectively, it being understood that the pawl (14a for instance) assigned to a given ratchet wheel (6 for instance) is articulated on rivet 13 which bears at the same time the spring (15a for instance) which loads the pawl (14c for instance) acting on the other ratchet wheel (9 for instance). 
     At the same time, it is not indispensable that two pawls act simultaneously on a same ratchet wheel. In a simplified version of the reverser mechanism according to the invention, one would provide only the assemblies pawl-spring 14a, 15a and 14c, 15c or indeed the assemblies pawl-spring 14b, 15b and 14d, 15d. 
     The advantage of the double arrangement seen on figure 3 consists in that one may displace the ends of the pawls acting on a common ratchet wheel by a half-tooth which reduces by half the minimum path of the oscillating mass required to obtain a winding action relative to the case in which a single pawl per ratchet wheel is provided. 
     However, whatever be the solution adopted, in view of the fact that each rivet receives a pawl and a spring, not only is the mechanism simplified, takes up less space and requires fewer machining operations and smaller pieces, but simplifies likewise the assembly of the mechanism. 
     The cut-out provided on the flange 17 of each rivet 13 in order to form edge 18 facilitates engagement of the elastic blade 25 below such flange and avoids too great a deformation during such operation. 
     The operation of the reverser mechanism appears on FIG. 7. 
     The oscillating mass 5 being moved in both directions, the winding wheel 1 follows it in these movements by displacing pawls 14a to 14d. 
     If the direction corresponds to the arrow F1 of figure 7, pawls 14a and 14b are engaged in the teeth of the ratchet wheel 6 while pawls 14c and 14d slip relative to ratchet wheel 9. Wheel 6 being coupled to wheel 7, wheel 8 is driven in the direction of arrows F3. 
     If, on the other hand, winding wheel 1 turns in the direction of arrow F2, pawls 14c and 14d are engaged in the teeth of ratchet wheel 9 while pawls 14a and 14b slip relative to ratchet wheel 6. Wheel 9 is wedged onto pinion 10 then drives wheel 8 in the direction of arrows F3 in view of the intermediate wheel 11. 
     Stem 16 of each rivet 13 includes at its free end a conical recess 21 which is coaxial with the rivet. In its mounted position each rivet 13 retains a pawl 14a to 14d between its flange 17 and the facing surface of plate 1a. Each pawl bears to this effect an articulation portion 22 being adjusted to the cylindrical portion 19 of the corresponding rivet. It includes likewise an active heel 23 which cooperates with the ratchet wheel 6 or 9 which is found situated on the same side of the plate 1a. 
     The end of each rivet opposite flange 17 projects beyond the plate 1a by a certain distance in order to receive the fastening portion 24 of a spring 15a to 15d from which extends an active elastic blade 25 cooperating with the conjugate pawl 14a to 14d which is located on the same surface of plate 1a. The free end of each active elastic blade 25 is supported against a rectilinear edge 26 provided on the articulation portion 22 of the pawl 14a to 14d with which it cooperates. 
     The fastening portion 24 of each spring 15a to 15d includes a hole 27 of the same form as the holes 12 in plate 1a. The springs are thus blocked from rotation on their corresponding rivet while they are likewise axially blocked thanks to a deformation towards the exterior of the end of the stem of each rivet, effected following mounting of each assembly on plate 1a. This deformation operation acts as riveting.