EP3889689A1 - Motor member for a timepiece - Google Patents

Abstract

Motor unit (1) for a timepiece comprising: - a mainspring (7); - a drum (5) delimiting an outer wall of a housing housing said mainspring (7), an outer end of said mainspring (7) ) being linked to said drum (5), said drum (5) being arranged to pivot about an axis of rotation and having the shape of a toothed annular ring; - a toothed wheel (11) integral with a bung (9) ) to which an inner end of said mainspring (7) is connected; in which an open face of said housing is intended to be closed by being positioned facing a fixed element (3) of the timepiece against which said drum (5) is intended to be mounted.According to the invention, the plug (9) and said toothed wheel (11) come in one piece, said drum (5) being supported by a ball bearing (37) comprising a first groove (38a) located on the outer wall of said drum and a second groove (38b) facing said first th groove (38a), said second groove (38b) being located on the inner wall of an outer ring (39) arranged to be fixed to said fixed element (3), a plurality of balls being housed in the cavity formed by said grooves (38a, 38b).

Description

Technical area

The present invention relates to the field of watchmaking. It relates, more particularly, to a motor unit with reduced bulk.

State of the art

Currently, the most commonly used driving member in mechanical timepieces is the barrel. Typically, a barrel comprises a hollow drum comprising a cylindrical wall closed on one side by a bottom formed integrally with it, and on the other side by a cover, in order to form a housing for a spiral spring. The outer end of the spiral spring is linked by a fixed or sliding flange to the cylindrical wall of the drum, and the inner end of the spring is linked to a bung associated with a barrel shaft. The outer wall of the drum is typically provided with teeth in order to drive a finishing gear, and the shaft is integral with a ratchet wheel, which is used for winding the spring. It is also known practice to drive the finishing gear train via the shaft and to wind the spring via the drum. Furthermore, smooth drums, devoid of toothing, are known, which drive the finishing gear train by means of a chain and a spindle system.

The conventional barrel mentioned above is mounted on the frame by its center, in particular directly or indirectly via the shaft. This arrangement is relatively bulky, and requires a certain height between the frame elements located on either side of the barrel in order to ensure that the barrel does not come into contact with neighboring components.

Solutions to this problem have already been proposed in the prior art. For example, the patent CH26510 omits the drum cover, the housing for the spring being delimited on one side by the bottom of the drum, and on the other side by a frame element of the movement, in particular the plate.

An even more compact solution was proposed in the document CH 46863 . The driving member of this document proposes a drum which is also closed on one side by a frame element, in which the shaft comes in one piece with a wheel which is located completely within the thickness of this frame element, in a recess provided in the latter.

The drums of all the embodiments mentioned above are supported by their center, which requires the drum to have a bottom integral with its side wall. The document CH 334702 reveals several variants of barrels in which the drum consists of a ring guided at its peripheral wall by means of three pairs of rollers distributed around the periphery of the drum. This drum has neither cover or bottom, and the housing for the mainspring is defined on its lower and upper faces by bridges of the movement frame.

Although the barrels disclosed in the latter document result in a significant reduction in height compared to a conventional barrel, the use of pairs of rollers located around the drum increases the diameter of the barrel, and increases the complexity of the motor member. Furthermore, the rollers are rotary, and therefore require axes of rotation. There are therefore four axes (the shaft and those of the three pairs of rollers) which must be properly aligned when mounting the barrel bridge on the plate, which causes some difficulty in its assembly.

Finally, the document FR 2229087 discloses a motor member in which the drum is supported radially by a recess made in the bottom of the housing, this bottom serving as a frame element. The drum is open on both sides, and the housing thus defined to house the spring is closed on the one hand by the bottom and on the other hand by the toothed wheel. This arrangement is even simpler and more compact than those mentioned above, but the toothed wheel is supported on both sides. The compactness of the motor unit as well as its simplicity can therefore be further improved.

An object of the invention is therefore to provide a motor member in which the aforementioned defects are at least partially overcome.

Disclosure of the invention

More precisely, the invention relates to a driving member for a timepiece which comprises a driving spring such as a spiral spring, and a drum delimiting an outer wall of a housing housing said driving spring. The outer end of the mainspring is linked to the drum, which is arranged to pivot about an axis of rotation. Furthermore, the drum has the shape of a toothed annular crown.

The drive member further comprises a toothed wheel, which can for example serve as a ratchet wheel, integral with a bung to which an inner end of said drive spring is linked.

One face of said housing is intended to be defined by a fixed element of said timepiece against which said drum is intended to be mounted, such as a frame element, a back, or a crystal.

According to the invention, said plug and said toothed wheel are made in one piece. This construction results in a significant reduction in bulk compared to the barrels of the prior art. The combination of a toothed wheel coming in one piece with the bung (and therefore compact) with a drum formed by a toothed annular crown and therefore devoid not only of a cover but also of a bottom, allows a very thin construction The separate bung is thus made superfluous, which reduces the number of parts. Furthermore, the fact that the toothed wheel and the toothed wheel are made in one piece makes it possible to bring the wheel closer to the drum, without having to leave any room to compensate for the necessary tolerances when using two separate parts integral with each other.

For the rest, said drum is supported by a ball bearing. The friction undergone by the drum during its rotations can therefore be minimized, while keeping the thickness of the motor member to a minimum. The ball bearing can be bidirectional, or unidirectional. This last possibility allows the drum to function as a ratchet, without requiring any pawl, in the event that the motor member is reassembled by the drum.

More particularly, said ball bearing comprises a first groove located on the outer wall of said drum and a second groove facing said first groove, said second groove being situated on the inner wall of an outer ring designed to be fixed to said element fixed, the grooves thus defining an annular cavity. A plurality of balls are housed in this annular cavity. A compact construction is thus proposed.

Advantageously, said drum and said motor member can come from one piece, which reduces the number of parts of the motor member and facilitates its assembly.

Advantageously, the motor member as defined above is integrated into a timepiece movement which said fixed element comprises.

Advantageously, said toothed wheel can be mounted to pivot on a fixed shaft extending from the fixed element or from the barrel bridge.

Advantageously, said fixed element may be a frame element of a watch movement of said timepiece such as a plate or a bridge, or a crystal that a timepiece comprises on the back side or on the dial side, or else a bottom that the said timepiece comprises.

In the case where the fixed element is a glass of the timepiece, said barrel bridge can be integrated into a frame element or into a back that comprises said timepiece.

Brief description of the drawings

• La figure 1 est une vue en coupe d'une première variante d'un organe moteur ne faisant pas objet de l'invention ;
• La figure 2 est une vue agrandie de la moitié gauche de la figure 1 ;
• La figure 3 est une vue en perspective de l'organe moteur de la figure 1 ;
• La figure 4 représente le pont de barillet en perspective, vu des deux côtés ;
• La figure 5 représente le tambour en perspective, vu des deux côtés ;
• La figure 6 représente une partie de l'élément de bâti sur lequel l'organe moteur de la figure 1 est monté ;
• La figure 7 représente la roue dentée de la première variante en perspective, vu des deux côtés ;
• La figure 8 est une vue en coupe d'une deuxième variante d'un organe moteur ne faisant pas objet de l'invention ;
• La figure 9 est une vue agrandie de la moitié gauche de la figure 7 ;
• La figure 10 est une vue éclatée de ladite deuxième variante d'un organe moteur ;
• La figure 11 est une vue perspective d'une variante du tambour et du ressort moteur ;
• La figure 12 est une vue perspective coupée d'une variante d'un organe moteur selon l'invention ;
• La figure 13 est une vue élargie d'un détail de la figure 12 ;
• La figure 14 est une vue en plan de la variante de la figure 12 ;
• La figure 15 est une vue en perspective d'encore une variante d'un organe moteur ne faisant pas objet l'invention ; et
• La figure 16 est une vue en coupe de la variante de la figure 15.

Other details of the invention will emerge more clearly on reading the following description, given with reference to the appended drawings in which:

• The figure 1 is a sectional view of a first variant of a motor member not forming the subject of the invention;
• The figure 2 is an enlarged view of the left half of the figure 1 ;
• The figure 3 is a perspective view of the motor organ of the figure 1 ;
• The figure 4 shows the barrel bridge in perspective, seen from both sides;
• The figure 5 shows the drum in perspective, seen from both sides;
• The figure 6 represents a part of the frame element on which the motor of the figure 1 has climbed ;
• The figure 7 shows the toothed wheel of the first variant in perspective, seen from both sides;
• The figure 8 is a sectional view of a second variant of a motor member not forming the subject of the invention;
• The figure 9 is an enlarged view of the left half of the figure 7 ;
• The figure 10 is an exploded view of said second variant of a driving member;
• The figure 11 is a perspective view of a variant of the drum and the mainspring;
• The figure 12 is a cutaway perspective view of a variant of a motor member according to the invention;
• The figure 13 is an enlarged view of a detail of the figure 12 ;
• The figure 14 is a plan view of the variant of the figure 12 ;
• The figure 15 is a perspective view of yet another variant of a motor member not forming the subject of the invention; and
• The figure 16 is a sectional view of the variant of the figure 15 .

Modes of Carrying Out the Invention

The figures 1 to 7 show a first variant of a motor member 1 not forming the subject of the invention, which has been provided by way of example. The driving member 1 is mounted on a fixed element 3 of a timepiece in which the driving member is used. This fixed element 3 can be a plate or a bridge, or else a base on which the motor member 1 is directly or indirectly mounted.

The motor member comprises a drum 5 having a peripheral toothing 6. This drum 5 has no cover and no bottom, and defines a cylindrical housing in which is disposed a motor spring 7. The latter is of conventional shape, spiral, and is connected at its outer end to the inner wall of the drum 5, and at its inner end to a bung 9. The latter comes in one piece with a toothed wheel 11 which serves as a ratchet wheel in the illustrated embodiment, but which can also be used for driving the cogs, the drum 5 serving as a ratchet in such a case. The toothed wheel 11 extends in superposition of the spring 7, and serves as a barrel cover, but the bung may consist of a separate part secured to the toothed wheel 11. The bung 9 is pivoted around a fixed shaft 13 , and is held on the latter by means of a screw 15 or the like which rests against the fixed shaft 13. As best seen on the figure 7 the bung 9 comprises a hook 9a for connection with the inner end of the mainspring 7 formed directly in the bung 9, for example by means of wire EDM or sinking. Alternatively, it can be achieved by broaching or traditional milling.

The toothed wheel 11 acts as a cover for the barrel, which is not integral in rotation with the drum 5, as known for example in the document CH 28684 .

On its side opposite to the toothed wheel 11, the barrel is closed by a surface of the fixed element 3. The drum 5 as such has no bottom and cover, and is only a simple toothed ring.

The drum 5 is positioned axially and radially by guide elements 17 distributed around the periphery of the drum 5. As best seen on the figures 3 and 4 , these guide elements 17 are, in the variant shown, studs, made here in the form of stones, driven into a barrel bridge 19, and which abut against a shoulder 21 provided on the drum 5. An advantage of the use of stones, such as rubies, for the studs is the low coefficient of friction of this material, but other materials are possible. For example, the pads 17 may be made of hard metal, polymer or ceramic, and, in the case of metal, may be integral with the barrel bridge 19. Alternatively, the pads may be replaced by a continuous or discontinuous surface of the cylinder. barrel bridge 19, or by ball bearings. The studs 17 extend from the barrel bridge 19 in a direction parallel to the axis of rotation of the drum 5, and do not extend radially beyond the peripheral teeth 6 of the drum 5. In fact, the elements of guide 17 are inscribed in the diameter of the drum 5, which reduces the bulk in the plane of the drum 5 with respect to the document CH 334702 aforementioned.

In principle, the drum 5 can simply abut against the surface of the fixed element 3 and slide on the latter during its pivoting. However, in order to reduce friction, the drum 5 comprises guide stones 23 driven into corresponding housings and extending in the direction of the fixed part 3. These guide stones reduce the contact surface between the drum 5 and the fixed part 3 as well as the coefficient of friction.

The barrel bridge 19 also comprises a winding pawl 25 which cooperates in a known manner with the teeth of the toothed wheel 11. Furthermore, the lower face of the barrel bridge 19 comprises a recess 27 which serves to allow a mobile of the cylinder. finishing gear (not shown) to mesh with peripheral toothing 6 of drum 5.

The barrel bridge 19 is fixed to the fixed element 3 by means of screws 29 engaged in threaded tubes 31, which project from the upper face of the fixed element 3. These tubes 31 serve as as centering studs for the barrel bridge 19, and ensure its positioning on the fixed element 3. Alternatively, the bridge can be fixed to the fixed element 3 by means of other fixing methods such as clipping, punching or gluing.

The figures 8 to 10 illustrate a second variant of a motor member 1 not forming the subject of the invention. This variant differs from that of figures 1 to 7 mainly in that its construction is the reverse of that of the latter.

In this variant, the fixed element 3 is a crystal, which can be located either on the dial side or on the back side, and delimits the housing of the mainspring 7 on one of its sides. The barrel bridge 19 can be a separate element, secured to the plate or to the bottom, or can come integrally with one of the latter. The term "bridge" used rather means a functional part of the structure of the motor member 1 which can be part of another element such as a plate or a bottom.

The barrel bridge 19 of this variant comprises a hollow 20 in its bottom, in which the toothed wheel 11 is located, which is pivoted around a fixed shaft 13 which said bridge 19 comprises. The axial positioning of the toothed wheel 11 is secured on one side by a stop 33, and on the other side by the glass 3.

The drum 5 is superimposed on the toothed wheel 11, and is guided in rotation and axially by guide elements 17 similar to those of the first variant, and which also extend from the barrel bridge 19 in the direction of the element. fixed 3 in a direction parallel to the axis of rotation of the drum 5. As for the other variant, the guide elements 17 cooperate with the shoulder 21 located on the drum 5 in order to ensure the positioning of the latter.

The guide elements 17 are located in blind holes 35 which are deeper than necessary to receive the guide elements 17 in order to allow the watchmaker to adjust the height of the latter according to his needs. Alternatively, the blind holes 35 may have a sufficient depth to receive the guide elements 17 to the bottom of the holes 35.

On the other face of the drum 5, the latter is guided simply by the fixed element 3 against which the drum 5 abuts. Nevertheless, it is possible to envisage providing guide stones 23 in the drum which extend in the direction of the glass 3 in a manner analogous to the variant of figures 1 to 7 .

• montage de la roue dentée 11 sur l'axe fixe 13 ;
• montage du tambour 5 en superposition de la roue dentée 11 ;
• montage du ressort moteur 7 dans le tambour 5 et accroche de celui-ci sur la bonde 9 de la roue dentée 11 ;
• montage de la glace.

This variant is assembled in the following order:

• mounting the toothed wheel 11 on the fixed axis 13;
• mounting of the drum 5 in superposition of the toothed wheel 11;
• mounting the mainspring 7 in the drum 5 and hooks the latter onto the plug 9 of the toothed wheel 11;
• mounting the ice.

In a variant not shown, the axial positioning of the toothed wheel 11 can be ensured not by the glass 3, but by the drum 5 which can serve as an axial stop.

The figure 11 illustrates a variant of the drum 5 and of the mainspring 7 which can be implemented in connection with all of the aforementioned embodiments. The drum 5 as well as the mainspring 7 form a one-piece assembly, coming in one piece. The internal end of the mainspring 7 also comprises a ferrule 7a allowing a kinematic connection with the toothed wheel 11, but this ferrule 7a can obviously be omitted. In the example illustrated, the ferrule comprises a polygonal opening, but other known shapes are also possible. A mainspring 7 of this type can be made of metal, or silicon-based material (for example amorphous, monocrystalline or polycrystalline silicon, its mono- or polycrystalline oxide, carbide or nitride), alumina, polymer, composite or similar.

Since the construction of the illustrated motor member 1 includes many contact surfaces between moving parts, it could be advantageous to provide a fine polishing or diamond coating of the contact surfaces, or to perform a surface treatment such as deposition of DLC (carbon in diamond form), nanostructuring, teflonnage, electroplating or ion implantation on one or more surfaces intended to undergo friction.

The figures 12 to 14 illustrate a variant of a motor member 1 according to the invention. In this variant, the toothed wheel 11 is supported on a fixed shaft 13 in a similar manner to the variant of figures 1 to 3 , and the housing for the mainspring is defined on both sides by the toothed wheel 11 as well as a fixed element 3 of the timepiece, such as a frame element.

However, the drum 5 is maintained in its axial and radial positions by means of a ball bearing 37. This ball bearing 37 consists of a first groove 38a provided on the outer wall of the drum 5, and of a second groove 38b formed in the inner face of an outer ring 39. The two grooves 38a, 38b are one facing the other in order to define a cavity, and balls (not shown) take place in this cavity in a generally known manner.

In the illustrated variant, the first groove 38a is formed by a first bevelled surface 5a provided on the outer face of the drum 5, which is adjacent to a second bevelled surface 41a with which an inner ring 41 is provided. The latter is driven out, glued. , welded or otherwise secured to the outer face of the drum 5, but it is also possible to form the first groove 38a directly in the body of the drum 5, which would therefore be in one piece.

The outer ring 39 is held in place by a bridge 19 as well as screws 43, which hold it against a shoulder 45 provided on the fixed element 3 to which it is thus fixed.

The drum 5 is thus suspended by the ball bearing 37, and does not come into contact with either the fixed element 3 or with the toothed wheel 11. Consequently, and unlike the other variants described above, no member additional guidance is required. The friction undergone by the drum during its pivoting can thus be reduced to a minimum value. Moreover, this variant has an exceptionally thin thickness.

The figures 12 to 14 also illustrate the arrangement of the gears with the toothed wheel 11 and with the drum 5. We can clearly see a reference 47 which is in the same plane as the toothed wheel 11 which meshes with this last, as well as another reference 49 which is in the same plane as the toothing 6 of the drum 5 and also meshes there with. The references 47, 49 therefore pass on either side of the outer ring 39.

This arrangement still presents other possibilities for other construction variants. First, the same considerations with respect to the configuration of the mainspring 7 set out above (monobloc spring with drum 5, conventional spring, etc.) also apply here. It is also possible to reassemble the motor member by its drum 5 and to use the toothed wheel 11 as a power take-off for the movement.

In the latter case, if the ball bearing 37 is of the unidirectional type, the motor member can be wound up by the drum 5 without requiring any pawl, thus reducing the number of components used in the construction. Moreover, this arrangement eliminates the overvoltage during the winding of the mainspring 7 by the dead angle of a unidirectional bearing.

The figures 15 to 16 illustrate an additional variant of a motor member 1 not forming the subject of the invention. This variant differs from that of figures 1 to 7 mainly in that the drum 5 is positioned radially by guide elements carried or integral with the fixed element 3, and axially on the one hand by the fixed element 3, on the other hand by the toothed wheel 11.

More precisely, the fixed element 3 comprises a recess 22 in which the drum 5 is placed. The side wall 22a of this recess 22 forms a guide element making it possible to position the drum 5 radially and axially limit the position of the drum 5 in a first direction. Other forms of guide elements are also possible, such as, for example, studs integral with the fixed element 3 which take place in a circular groove provided in the underside of the drum 5 or vice versa, or a system of one or more several circular grooves or rails distributed between the fixed element 3 and the drum 5, which interact for the same purpose.

In the illustrated variant, the drum 5 simply abuts against the surface of the fixed element 3 and slides on the latter during its pivoting. However, it is also possible to provide guide members 17 such as stones on the drum 5 or on the fixed element 3, or to arrange a ball bearing in the underside of the drum 5 in order to reduce friction.

In the direction opposite to the axial stop defined by the recess 22 of the fixed element 3, the axial displacement of the drum 5 is limited by the toothed wheel 11. The latter is supported on a fixed shaft 13 in a similar manner to the variant of figures 1 to 3 , and said toothed wheel 11 has an outside diameter large enough to cover or overlap, at least partially, an area of the drum 5. This at least partial overlap makes it possible to define a second axial stop for the drum 5 in the direction opposite to the axial stop previously defined by the hollow of the fixed element 3. In other words, the drum 5 is sandwiched between the fixed element 3 and the toothed wheel 11.

Advantageously, this variant offers a reduced number of parts and makes it possible to dispense with the presence of a barrel bridge.

Although the invention has been described in connection with particular embodiments, it is obvious that it is in no way limited thereto and that it comprises all the technical equivalents of the means described as well as their combinations if these come within the scope of the invention as defined by the claims.

Claims (7)

Motor unit (1) for a timepiece comprising: - a mainspring (7); - a drum (5) delimiting an outer wall of a housing housing said mainspring (7), an outer end of said mainspring (7) being linked to said drum (5), said drum (5) being arranged to pivot around it 'an axis of rotation and having the shape of a toothed annular crown; - a toothed wheel (11) integral with a plug (9) to which an inner end of said mainspring (7) is linked; wherein an open face of said housing is intended to be closed by being positioned facing a fixed element (3) of the timepiece against which said drum (5) is intended to be mounted,
characterized in that said plug (9) and said toothed wheel (11) are made in one piece,
and in that said drum (5) is supported by a ball bearing (37) comprising a first groove (38a) located on the outer wall of said drum and a second groove (38b) facing said first groove (38a) ), said second groove (38b) being located on the inner wall of an outer ring (39) arranged to be fixed to said fixed element (3), a plurality of balls being housed in the cavity formed by said grooves (38a, 38b ). Motor unit (1) according to claim 1, wherein said drum (5) and said motor member (7) are integrally formed. Watch movement comprising a motor member (1) according to one of claims 1 to 2. Watch movement according to claim 3, wherein said toothed wheel (11) is pivotally mounted on a fixed shaft (13) extending from one of the fixed element (3) or from the barrel bridge (19). Watch movement according to one of claims 3 to 4, wherein said fixed element (3) is a frame element of said movement. Timepiece comprising a watch movement according to one of claims 3 to 5. Timepiece according to Claim 6, in which the said fixed element is a crystal (3) which the said timepiece comprises or a back which the said timepiece comprises.

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