CH713409B1 - Balance wheel for balance-spring of the thermocompensated type, balance-spring of the thermocompensated type, movement and timepiece. - Google Patents

Abstract

The object of the invention is to provide a balance wheel for a balance-spring of the thermocompensated type, a movement and a timepiece. A balance for a balance-spring of the thermocompensated type comprises a main balance body (62) comprising a balance shaft (61) extending along a first axis (O1) and arranged to be driven in rotation around the first axis (O1) by the power of a hairspring (63). The balance for a balance-spring of the thermocompensated type comprising an adjustment part (100) extending along a second axis (02), from a position where it is in rotational symmetry about the first axis (O1) of the main body (62) of the pendulum, allowing angular adjustment around the second axis (02) and comprising a part made of two materials (121) obtained by stacking together, in a direction crossing the second axis (02), materials (130, 131) having different expansion coefficients.

Description

BACKGROUND OF THE INVENTION

Field of the invention

The present invention relates to a balance for a balance-spring of the thermocompensated type, a balance-spring of the thermocompensated type, a movement and a timepiece.

Prior art

[0002] A balance-spring fulfilling the function of a regulator in a mechanical timepiece comprises a balance shaft extending along an axis, a balance wheel fixed to the balance shaft, as well as a hairspring . As the hairspring expands and contracts, the balance shaft and balance wheel perform a periodic alternating rotational motion (oscillation) around the axis.

[0003] With the balance-spring described above, it is important that the period of oscillation be set to a predetermined prescribed value. If the period of oscillation is shifted from the prescribed value, the rate of the mechanical timepiece (the amount by which the timepiece advances and retards) is changed.

[0004] The period of oscillation T of the balance-spring is expressed by the following equation (1). In equation 1, I is the „moment of inertia“ of the balance-spring and K is the „stiffness“ of the balance-spring.

[0005] According to equation 1, when the moment of inertia I of the balance-spring and the stiffness K of the spring are modified due to a change in temperature, the period of oscillation of the balance-spring is modified. More specifically, in some cases, the balance wheel described above is made of a material whose coefficient of expansion is positive (a material that expands with an increase in temperature). In this case, when the temperature increases, the balance wheel sees its diameter increase and the moment of inertia increases it. On the other hand, in certain cases, the hairspring is made of a material whose thermal coefficient of the Young's modulus is negative (for example a steel). In this case, when the temperature increases, the stiffness K decreases.

[0006] Thus, when the temperature increases, the moment of inertia I increases and the stiffness K decreases, which has the consequence that the period of oscillation T lengthens. As a result, the period of oscillation T of the balance-spring is short at a low temperature, and long at a high temperature, so that the thermal characteristic of the timepiece increases at low temperature and drops at high temperature.

[0007] As a measure to overcome the fact that the period of oscillation T depends on the temperature, it could be possible to employ a material with a constant modulus (for example Co-elinvar) as the material constituting the hairspring. By employing a constant modulus material, it would be possible to suppress the fluctuations of stiffness K with temperature changes and to suppress the influence of temperature on the period of oscillation T. However, to suppress the fluctuations affecting the thermal coefficient of Young's modulus, strict production conduct is required, and the production of the hairspring is difficult to perform.

[0008] On the other hand, as a measure to overcome that the period of oscillation T depends on the temperature, it could be possible to provide a bimetallic part in a position of rotational symmetry of the balance wheel. The bimetallic part is formed by stacking together flattened elements having different coefficients of expansion.

In this constitution, when the temperature increases, the bimetallic part undergoes a deformation, for example radially inwards, due to the difference between the coefficients of expansion of the flattened elements. As a result, the average diameter of the balance wheel is decreased, whereby it is possible to reduce the moment of inertia I. As a result, it is possible to correct the thermal characteristics of the moment of inertia I, thereby which makes it possible to eliminate the influence of the temperature on the period of oscillation T.

[0010] Further, for example, UK Patent No. 256953 (Patent Document 1) mentioned below discloses a constitution in which the effective length of each bimetallic piece (the amount by which it protrudes from the balance wheel) is changed so as to allow the amount of thermal coefficient correction (the amount by which the bimetallic part changes in the radial direction due to a change in temperature) to be changed. In this constitution, we must start from the principle that, by adjusting the effective length of each bimetallic part according to the thermal coefficient of the Young's modulus, it becomes easier to compensate for the variation of the thermal coefficient of the Young's modulus thanks to the thermal characteristic of the moment of inertia I.

[0011] However, the constitution of the aforementioned patent document 1 has a problem which is that it is difficult to make the effective lengths of the bimetallic parts equal. When the effective lengths of the bimetallic parts differ from each other, the center of gravity of the balance-spring is offset with respect to the axis of rotation. As a result, a balancing error is generated affecting the balance-spring, which results in a large fluctuation affecting the period of oscillation T due to the behavior of the balance-spring (what is called a difference in behavior is generated).

[0012] In addition, in the case where a material with a constant modulus is used as the material constituting the hairspring, there is the possibility that the temperature coefficient of the Young's modulus fluctuates more or less depending on the manufacturing conditions with which the production of the hairspring takes place (for example the dissolving and heating process).

However, in a balance-spring comprising a conventional bimetallic part, the thermal coefficient of the moment of inertia I (the slope of the thermal coefficient) can only be adjusted up or down.

SUMMARY OF THE INVENTION

The present invention has been made in view of the problems mentioned above. An object of the present invention is to provide a thermocompensated balance-spring, a movement and a timepiece which are of high quality and better in terms of thermocompensation performance.

To achieve the above object, according to the present invention, there is proposed a balance for a balance-spring of the thermocompensated type according to claim 1.

[0016] According to the invention, the part made of two materials undergoes deformation during a change in temperature, whereby the average diameter of the main rocker body is modified. As a result, it is possible to correct the thermal characteristic of the moment of inertia.

[0017] In particular, the adjustment part allows angular adjustment around the second axis, so that it is possible to change the orientation of the part in two materials according to the thermal coefficient of the Young's modulus of the hairspring. . As a result, the amount of thermal coefficient correction performed by the two-material workpiece can be changed both in the increasing direction and in the decreasing direction, whereby it is possible to correct the thermal coefficient of the moment of inertia of the balance-spring both in the direction of increase and in the direction of reduction. This means that a variation of the thermal coefficient of the Young's modulus can easily be canceled thanks to the thermal characteristic of the moment of inertia of the balance-spring. As a result, the period of oscillation of the balance-spring can be kept constant, which makes it possible to propose a balance-spring that is better with regard to the thermocompensation property.

[0018] Furthermore, even if the orientation of the part made of two materials is changed, the length, in the direction of the second axis, of the adjustment part is maintained at a fixed value. Consequently, contrary to the classic case in which the effective length of the part in two materials is modified, it is possible to avoid a displacement of the center of gravity of the balance-spring at a predefined temperature (ambient temperature for example of the order 23°C). As a result, it is possible to avoid the occurrence of a balancing error and to reduce the differences in behavior.

[0019] The balance for a thermocompensated balance-spring can be according to claim 2.

[0020]According to this possibility, the adjustment part is provided on the rim of the balance wheel, so that it is possible to move the adjustment part away from the first axis, in the first radial direction. As a result, it is possible to increase the amount of radial deformation of the fitting part (the difference, in the first radial direction, between the distance between the distal end of the fitting part at a preset temperature and the first axis and the distance between the distal end of the adjustment portion after a temperature change and the first axis), thereby increasing the amount of thermal coefficient correction due to the two-material workpiece.

[0021] The balance for a thermocompensated balance-spring can be according to claim 3.

[0022] According to this possibility, it is possible to obtain the amount of radial deformation resulting from a change in temperature, while preventing an increase in the size of the balance-spring from being caused by the addition of the part d 'adjustment.

The balance for a balance-spring of the thermocompensated type can be according to claim 4.

[0024] In this possibility, during a deformation, in the first radial direction, of the adjustment part due to a change in temperature, it is possible to avoid interference between the serge and the part of adjustment, which makes it possible to guarantee the amount of radial deformation of the adjustment part (the adjustment part can deform radially by the desired amount without abutting against the serge).

[0025] In the balance wheel for balance-spring of the heat-compensated type according to the invention, each adjustment part may comprise a flyweight.

[0026] With this possibility, it is possible to increase the mass of the adjusting part, so that it is possible to increase the amount of correction of the thermal coefficient due to the part made of two materials.

The balance for a balance-spring of the thermocompensated type can be according to claim 6.

[0028] With this possibility, it is possible to couple a tool to the coupling portion of the fixing portion, through the through-hole. Therefore, it is possible to easily perform the angular adjustment of the adjustment part around the second axis. Further, the angle of rotation of the adjusting part is changed through the fixing part, whereby, compared to the case where the angle of rotation of the adjusting part is changed through of the distal end (the two-material part and the flyweight), it is possible to avoid plastic deformation of the fitting part during the angular adjustment of the fitting part. Therefore, it is possible to preventing a rate change from occurring at a predetermined temperature due to plastic deformation of the adjustment part.

The balance for a balance-spring of the thermocompensated type can be according to claim 7.

[0030] With this possibility, it is possible to guarantee the (desired) amount of radial deformation resulting from a change in temperature and to increase the amount of correction of the thermal coefficient due to the part made of two materials.

The balance for a balance-spring of the thermocompensated type can be according to claim 8.

[0032]According to this possibility, the center of gravity of the adjustment part is on the second axis, so that, when the position of the adjustment part is adjusted around the second axis, it is possible to preventing the center of gravity of the adjustment part from shifting from the second axis due to the angle of rotation of the adjustment part, it follows that it is possible to avoid a shift of the center of gravity of the balance-spring depending on the angle of rotation of the adjustment part, so that it is possible to reliably reduce the difference in behavior.

The invention also relates to a balance-spring of the thermocompensated type according to claim 9.

[0034] The balance-spring of the thermocompensated type can be according to claim 10.

[0035] With this balance-spring, it is possible to reduce the variation of the Young's modulus caused by a change in temperature and to eliminate the dependence of the oscillation period on temperature. Further, in the present aspect, it is possible to correct the variation of the thermal coefficient of the Young's modulus by means of the rotation angle of the adjusting part, so that the production of the hairspring and the steering at the moment of the production of the hairspring are facilitated. Therefore, it is possible to improve the production efficiency of the balance spring and realize a cost reduction.

The invention also relates to a movement according to claim 11.

The invention also relates to a timepiece according to claim 12.

[0038] With the balance wheel for balance-spring of the thermocompensated type according to the invention, it is possible to propose a movement and a timepiece which are of high quality and which involve a small variation in rate.

According to the present invention, it is possible to provide a balance-spring of the thermocompensated type, a movement and a timepiece which are of high quality and which are better in terms of thermocompensation performance.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is an external view of a timepiece according to a first embodiment. Figure 2 is a plan view of a movement according to the first embodiment, as seen from the front side. Figure 3 is a plan view of a balance-spring according to the first embodiment, as seen from the front side. Figure 4 is a side view of the balance-spring according to the first embodiment. Figure 5 is a sectional view along line V-V of Figure 3. Figure 6 is a sectional view along line VI-VI of Figure 3. Figure 7 is a partial plan view of the balance- hairspring, serving to illustrate the operation of an adjustment part. FIG. 8 is an enlarged view, in section, of the adjustment part, this adjustment part being therein in a reference position. Figure 9 is an enlarged view, in section, of the adjustment part, this adjustment part being turned therein by an angle of 45°. Figure 10 is an enlarged view, in section, of the adjustment part, this adjustment part being turned therein by an angle of 90°. Figure 11 is an enlarged view, in section, of the adjustment part, this adjustment part being turned therein by an angle of -45°. Figure 12 is an enlarged view, in section, of the adjustment part, this adjustment part being turned therein by an angle of -90°. Fig. 13 is a graph showing the rotation between the orientation of the two-material workpiece and the amount of deformation of the two-material workpiece when the angle by which the adjustment part is rotated is changed within the range of - 90 degrees to +90. Fig. 14 is a graph showing the rotation between the angle by which the adjustment portion is rotated and the amount of radial change (R). FIG. 15 is a graph showing the relationship between temperature (°C) and rate due to a difference in the thermal coefficient of the Young's modulus of the hairspring. FIG. 16 is a perspective view of a balance-spring according to a second embodiment. Figure 17 is a plan view of a balance-spring according to a variant, as seen from the front side. Figure 18 is a sectional view, corresponding to Figure 6, and represents a variant. Figure 19 is a partial view, in plan, of a balance-spring according to a variant.

DESCRIPTION OF EMBODIMENTS

In the following, embodiments of the present invention will be described with reference to the drawings.

First embodiment

timepiece

[0042] Figure 1 is an external view of a timepiece 1. In what follows, to facilitate understanding of the drawings, timepiece components are omitted and, in some cases, components of timepiece are represented in a simplified form.

As shown in Figure 1, in the timepiece 1 of this embodiment, a movement 2, a dial 3, various indicator hands 4 to 6, etc. are incorporated in a timepiece case 7 .

[0044] The timepiece box 7 comprises a main box body 11, a lid (not shown) and a crystal 12. A crown 15 is provided at the 3 o'clock position (on the right side in Figure 1) from the side surface of the main case body 11. The crown 15 is used to actuate the movement 2 from outside the main case body 11. The crown 15 is fixed to a winding stem 19 introduced into the main case body 11.

[0045] Figure 2 is a plan view of the movement 2 as seen from the front side.

As shown in Figure 2, in movement 2, several mobiles, etc., are rotatably supported by a main plate 21 forming the base plate of movement 2. In the following description, crystal side 12 (the dial side 3) of the timepiece case 7 with respect to the main plate 21 will be called the "rear side" of the movement 2, while the case cover side (the side opposite the dial side 3) will be called the „front side“ of movement 2. In addition, all the spindles described below are provided so that the antero-posterior direction of movement 2 is their axial direction.

The aforementioned winding stem 19 is incorporated into the main plate 21. The winding stem 19 is used to correct the date and time. The winding stem 19 is rotatable on its axis and movable in the axial direction. The position of winding stem 19 in the axial direction is determined by a switching device comprising a pull tab 23, a rocker 24, a rocker spring 25 and a pull tab jumper 26.

When the winding stem 19 is rotated, the winding pinion 31 rotates due to the rotation of a clutch wheel (not shown). Due to the rotation of the winding pinion 31, a crown wheel 32 and a ratchet 33 rotate in sequence and a barrel spring (not shown) housed in the movement barrel 34 is wound.

The movement barrel 34 is rotatably supported between the main plate 21 and the barrel bridge 35. A center wheel set 41, an average wheel set 42 and a second wheel set 43 are rotatably supported between the main plate main 21 and the gear train 45.

[0050] When the movement barrel 34 is driven in rotation by the mainspring maintenance force, the center wheel set 41, the average wheel set 42 and the second wheel set 43 rotate consecutively. The movement barrel 34, the center wheel set 41, the middle wheel set 42 and the second wheel set 43 form the front wheel train.

The minute hand 5 (see Figure 1) is mounted on the center wheel set 41 of the aforementioned front gear train. The hour hand 4 is mounted on an hour wheel (not shown) rotating with the rotation of the center mobile 41. In addition, the seconds hand 6 (see FIG. 1) rotates according to the rotation of the mobile second 43.

[0052] An exhaust regulator 51 is mounted in movement 2.

The escapement regulator 51 comprises an escape wheel set 52, an anchor 53 and a balance-spring 54 (balance-spring of the thermocompensated type).

The escapement wheel set 52 is rotatably mounted between the main plate 21 and the gear-train bridge 45. The escape wheel set 52 rotates with the rotation of the second wheel set 43.

The anchor 53 is supported between the main plate 21 and an anchor bridge 55 so as to be able to perform an alternating rotational movement. Anchor 53 includes a pair of vanes 56a and 56b. The pallets 56a and 56b are alternately engaged with the escapement wheel 52a of the escapement wheel set 52 due to the alternating rotational movement of the lever 53. When one of the two pallets 56a and 56b is engaged with the escapement wheel 52a, escapement wheel set 52 temporarily stops rotating. When the two pallets 56a and 56b are at a distance from escape wheel 52a, escape wheel set 52 rotates. These operations are repeated consecutively, whereby the mobile 52 rotates intermittently. Due to the intermittent rotational movement of the escapement wheel set 52, the aforementioned gear train (front gear) works intermittently, whereby the rotation of the front gear is controlled.

Balance-spring

[0056] Figure 3 is a plan view of a balance-spring 54 as seen from the front side. Figure 4 is a side view of sprung balance 54. As shown in Figures 3 and 4, sprung balance 54 controls escapement wheel 52 (it causes escapement wheel 52 to escape at a fixed speed). The balance-spring 54 mainly comprises a balance shaft 61, a balance wheel 62 and a hairspring 63.

As shown in Figure 4, the balance shaft 61 is supported between the main plate 21 and a cock 65 so as to be rotatable on a first axis O1. In the following description, in some cases, the direction along the first axis O1 will be called the direction of the first axis, the direction orthogonal to the first axis O1 will be called the first radial direction and the direction around the first axis O1 will be called the first peripheral direction. In the present case, the direction of the first axis coincides with the anteroposterior direction.

The balance shaft 61 performs an alternating rotation movement according to a constant oscillation cycle, on the first axis O1, due to the power received from the hairspring 63. The front end, in the direction of the first axis , of the balance shaft 61 is supported by the cock 65, via a bearing (not shown). The rear end in the direction of the first axis, of the balance shaft 61 is supported by a bearing (not shown) formed in the main plate 21.

A double plate 67 is fitted on the rear end, in the direction of the first axis, of the balance shaft 61. The double plate 67 is shaped like a tube disposed coaxially with the first axis O1. A chainring peg 68 is provided on a portion, along the first peripheral direction, of the double chainring 67. Repeatedly, the chainring peg 68 engages with and disengages from the fork of the anchor 53, in a synchronized manner with the alternating rotational movement of the balance-spring 54. As a result, the lever 53 performs an alternating rotational movement, whereby the pallets 56a and 56b are repeatedly engaged with and disengaged from the escapement wheel set 52 .

[0060] Figure 5 is a sectional view along the line V-V of Figure 3.

As shown in Figures 3 and 5, the balance wheel 52 is fixed to the balance shaft 61, on the front of the double plate 67 in the direction of the first axis. The balance wheel 62 essentially comprises a hub 71, spokes 72 and a rim 73. In the present embodiment, the hub 71, the spokes 72 and the rim 73 are one-piece and are made of a metal (for example brass ).

The hub 71 is fixed to the balance shaft 61 by driving or the like.

The spoke 72 extends outwards in the first radial direction, from the hub 71. In the present embodiment, the spokes 72 extend in the first radial direction, from opposite positions with , between them, the first axis O1 of the hub 71. The positions, the number, etc., of the spokes 72 can however be modified as needed.

The serge 73 has an annular shape and it is arranged coaxially with the first axis O1. The rim 73 surrounds the hub 71, on the outer side in the first radial direction. On the outer side in the first radial direction, one end of spoke 72 is connected to the inner peripheral surface of rim 73.

[0065] The hairspring 63 is a flat hairspring, extending spirally in a plan view obtained when looking from the direction of the first axis. Hairspring 63 is wound so as to extend in an Archimedean spiral. The inner end of balance spring 63 is connected to balance shaft 61 via a ferrule 75. The outer end of balance spring 63 is connected to cock 65 via a stud (not shown) . The hairspring 63 is used to store the power transmitted from the second wheel 43 to the escapement wheel 52, and to transmit it to the balance shaft 61.

[0066] In the present embodiment, a material with a constant modulus (for example Co-elinvar) is suitably employed for the hairspring 63. The thermal characteristic of the hairspring 63 is such that it has a positive Young's modulus on the operating temperature range. In this case, the thermal coefficient of the Young's modulus of balance spring 63 is adjusted so that the period of oscillation of balance-spring 54 is as fixed as possible with respect to the thermal characteristic of the moment of inertia of the wheel. pendulum 62 accompanying a change in temperature. However, balance spring 63 can be made of a material other than a constant modulus material. In this case, as the constituent material of balance spring 63, it is possible to use a general steel whose Young's modulus has a negative thermal coefficient (behaviour according to which the stiffness decreases during a temperature increase).

[0067] Here, the sprung balance 54 of this embodiment comprises two adjustment parts 100 placed in positions having rotational symmetry (invariance by rotation of these positions) around the first axis O1 of the balance wheel 62 (symmetry of order 2 in the present embodiment).

[0068] Here, the expression rotational symmetry is an example of an expression for characterizing a figure and it is a well-known concept. More precisely, n being an integer equal to or greater than 2, the property of a figure which is superimposed on itself (rotation invariant figure) when it is applied a rotation of 360/n degrees around a certain center (in the case of a two-dimensional figure) or around an axis (in the case of a three-dimensional figure) is called n-order symmetry or 360/n degree symmetry. For example, when n=2, a 180 degree rotation of the figure results in it superimposing itself (it is unchanged), i.e. there is order symmetry 2. Each adjustment part 100 has the shape of a bar extending along the second axis 02 parallel to the tangent to the serge 73. The adjustment parts 100 are individually supported by a pair of support portions 110 provided continuously on the serge 73. The adjustment portions 100 have a similar construction and so do the support portions 110, so that the following description will focus on a single adjustment portion 100 and on a single support portion 110. In addition, in the following description, the direction along the second axis O2 will sometimes be called the direction of the second axis, and the direction orthogonal to the second axis will be called the second radial direction, while the direction around the second axis 02 will be called the second direction p peripheral.

[0069] Figure 6 is a sectional view along line VI-VI of Figure 3.

[0070] The support portion 110 forms an inward bulge, in the first radial direction, from the inner peripheral surface of the rim 73. A mounting hole 115 (through hole) is formed in the support portion 110. It extends through the support portion 110, in the direction of the second axis. The mounting hole 115 has a round (circular) shape in a front view obtained when looking from the direction of the second axis. The shape of the mounting hole 115 is not limited to the round shape. It can also be a rectangular shape, a triangular shape, etc.

A slot 116 communicating with the interior of the mounting hole 115 is formed in a part of the support portion, namely in its part located on the rear side in the direction of the first axis. The slot 116 is formed in the support portion 110, from one end to the other of the latter in the direction of the second axis.

As shown in Figure 4, an intervention hole 117 (through hole) extending through the serge 73 in the direction of the second axis is formed in the serge 73, where it passes in front of the hole mounting 115. The intervention hole 117 allows the insertion of a tool (not shown) (eg a flat end operating tool).

As shown in Figure 3, the adjustment part 100 is supported cantilevered by the support portion 110, on the inside of the rim 73. More specifically, the adjustment part 100 comprises a fixing portion 120, a bimetallic two-material (bi-material) part 121 and a flyweight 122, which are formed continuously from the proximal end (fixing end) to the distal end (free end), according to the direction of the second axis.

As shown in Figure 6, the fixing portion 120 is made, for example, of metal. In order to correspond to the aforementioned mounting hole 115, the fixing portion 120 has a circular shape in a front view obtained when looking from the direction of the second axis. The attachment portion 120 is driven into the aforementioned mounting hole 115 (which elastically retains it). The fixing portion 120 can be pushed out so as to straddle the mounting hole 115 and the intervention hole 117.

[0075] In the present embodiment, the degree of adjustment between the attachment portion 120 and the mounting hole 115 is chosen so that the adjustment part 100 can be rotated around the second axis O2 when a torque predetermined around the second axis 02 (second peripheral direction) is applied to the adjusting part 100. In other words, the adjusting part 100 of the present embodiment rotates around the second axis 02, the outer peripheral surface of the fixing portion 120 sliding on the inner peripheral surface of the mounting hole 115, whereby the position of the adjusting part 100 around the second axis O2 can be adjusted.

The shape of the cross section of the attachment portion 120 is not limited to the round shape. It can also be a rectangular shape, a triangular shape, etc. Further, while in the present embodiment as described above, the cross-sectional shape of the attachment portion 120 corresponds to the mounting hole 115, the attachment portion 120 and the mounting hole 115 may have different shapes when the fixing portion 120 can be rotated on the second axis 02.

As shown in Figure 4, a coupling portion 135 is formed on the proximal end surface, in the direction of the second axis, of the fixing portion 120. The coupling portion 135 is a groove s extending linearly in the second radial direction. A tool is inserted into the coupling portion, through the intervention hole 117. The coupling portion 135 is not limited to a groove since it can be coupled to a tool.

As shown in Figure 3, the part in two materials 121 is bonded (for example welded or glued) to the distal end surface, in the direction of the second axis, of the fixing portion 120. The part in two materials 121 has the form of a plate extending linearly in the direction of the second axis, on the internal side, in the first radial direction, of the rim 73. The part in two materials 121 is formed by stacking (adjoining) together, in the second radial direction, two flattened elements which differ by their coefficient of expansion (a low expansion element 130 and a high expansion element 131). In the present embodiment, invar (Ni-Fe alloy), silicon, ceramics or the like can be suitably employed as the material constituting the low expansion member 130. Copper, a copper alloy, aluminum or the like can suitably be used as the material constituting the high expansion member 131. The low expansion member 130 and the high expansion member 131 have a like shape (a rectangular shape in orthogonal cross section to the second axis 02). In the example shown, the boundary zone between the low expansion element 130 and the high expansion element 131 is at the level of the second axis 02. It is desirable that the center of gravity of each adjustment part 100 be located at the second axis 02. Thus, the thickness of the low expansion member 130 and the thickness of the high expansion member 131 may be different from each other (thickness may be changed as needed). In the event that the thickness of the low expansion element 130 and the thickness of the high expansion element 131 differ from each other, the boundary zone between the low expansion element 130 and the high expansion element 131 extends parallel to the second axis 02.

The part in two materials 121 (the low expansion element 130 and the expansion element 131) allows a change of orientation in the second radial direction, since the adjustment part 100 rotates around the second axis 02 The part in two materials 121 can deform according to the second radial direction during a change in temperature, which uses the difference between the coefficient of expansion of the element of low expansion 130 and the coefficient of expansion of the element of high expansion 131. The specific operation of the part in two materials 121 will be described later.

As shown in Figure 3, the weight 122 is bonded (for example welded or glued) to the distal end surface, in the direction of the second axis, of the part in two materials 121. The weight 122 is made , for example, metal. The cross section, perpendicular to the second axis O2, of the flyweight 122 is circular in shape. In a front view obtained looking from the direction of the second axis, the flyweight 122 has a larger external shape than the bimaterial part 121. The flyweight 122 can be mounted on the bimaterial part 121 so as to be removable .

Temperature correction method

A method for adjusting the amount of correction of the thermal coefficient will now be explained concerning the balance-spring 54 described above. Figure 7 is a partial plan view of the sprung balance 54, and serves to show the operation of the adjustment portion 100. In the state of Figure 7, the low expansion member 130 and the high expansion element 131 are arranged side by side along the first radial direction, within the part made of two materials 121, the low expansion element 130 being on the internal side along the first radial direction.

As shown in Figure 7, in the balance-spring 54 of this embodiment, when a change in temperature takes place, the part in two materials 121 undergoes a deformation, a bending, due to the difference between the expansion coefficient of the low expansion element 130 and the expansion coefficient of the expansion element 131. More precisely, when the temperature increases from a predetermined temperature T0 (ambient temperature, for example of the order 23°C), the high expansion element 131 expands more than the low expansion element 130. low expansion element 130 and high expansion element 131 (the inner side along the first radial direction in Figure 7). When the temperature drops from the predetermined temperature T0, the high expansion member 131 contracts more than the low expansion member 130. As a result, the adjusting portion 100 undergoes deformation toward the other side according to the stacking direction (the outer side along the first radial direction in Figure 7).

[0083] Due to the deformation of the adjustment part 100, the distance, in the first radial direction, between the distal end of the adjustment part 100 and the first axis O1 is modified. More precisely, if R0 is the distance, according to the first radial direction, between the distal end of the adjustment part 100 and the first axis O1 at the predetermined temperature T0 and if R1 is the distance, according to the first radial direction, between the distal end of the adjustment part 100 and the first axis O1 after the temperature change, the difference between the distance R0 and the distance R1 is the amount of radial change ΔR according to the first radial direction. It is possible to increase or decrease the average diameter of the balance wheel 62 in accordance with the amount of radial change ΔR, and to change the moment of inertia, around the first axis O1, of the balance-spring 54. In d In other words, in the event that the temperature increases, it is possible to reduce the average diameter of the balance wheel 62 in order to reduce the moment of inertia. In the case where the temperature has dropped, it is possible to increase the average diameter of the balance wheel 62 in order to increase the moment of inertia. As a result, it is possible to correct the thermal coefficient of the moment of inertia.

[0084] In the case where, as in the present embodiment, a material with a constant modulus is used as the material constituting the hairspring 63, there is the possibility that the thermal coefficient of the Young's modulus fluctuates more or less depending on the depending on the process conditions of the hairspring manufacturing process (e.g. dissolution and heat treatment).

On the other hand, in the present embodiment, the orientation of the part in two materials 121 (the angle of rotation θ around the second axis 02) can be changed according to the thermal coefficient of the Young's modulus of the spiral 63. More specifically, a tool is coupled inside the coupling portion 135 constituting the adjustment part 100 represented in FIG. 4, by the intervention hole 117. The tool is then turned on the second axis 02, whereby the adjustment part 100 rotates on the second axis 02, the outer peripheral surface of the fixing portion 120 sliding on the inner peripheral surface of the mounting hole 115. As a result, the angle of rotation θ is modified.

[0086] Figures 8 to 12 are enlarged views, in section, of the adjustment part 100.

In the state shown in Figure 8, the low expansion element 130 is located on the front side in the direction of the first axis, the low expansion element 130 and the high expansion element 131 being arranged side by side along the direction of the first axis. By using this state as the reference position (0 degrees) of the adjusting part 100, the angle of rotation θ around the second axis θ2 is adjusted. For example, in figure 9, the adjustment part 100 is rotated 45 degrees clockwise (+ direction), from the reference position, around the second axis 02. In the figure 10, the adjustment part 100 is rotated 90 degrees clockwise (+ direction), from the reference position, around the second axis 02.

[0088] In FIG. 11, the adjustment part 100 is rotated by -45 degrees in the counter-clockwise direction (direction -) from the reference position, around the second axis 02. On the Figure 12, the adjustment part 100 is rotated -90 degrees counterclockwise (direction -), from the reference position around the second axis 02.

Fig. 13 is a graph showing the relationship between the orientation of the two-material part 121 and the amount of deformation of the two-material part 121 when, at the same temperature (high temperature), the angle of rotation θ of the adjustment part 100 is changed in the range from -90 degrees to +90. In FIG. 13, the component along the first radial direction (hereinafter called X component) of the deformation vector of the part made of two materials 121 is on the abscissa. The component along the direction of the first axis (hereinafter called Y component) of the deformation vector of the part in two materials 121 is on the ordinate. In this case, in FIG. 13, the -X direction corresponds to the inner side in the first radial direction, while the +X direction corresponds to the outer side in the first radial direction. Further, in Fig. 13, the two-material part 121 at the origin represents the state at the predetermined temperature (T0) (before deformation).

As shown in Figure 13, when the adjustment part 100 is at the reference position (0 degrees), the two-material part 121 deforms only towards the front side, in the direction of the first axis (A1 in Figure 13). At the reference position, the component in Y of the deformation vector of the part in two materials 121 is therefore maximum and the component in X of the deformation vector of the part in two materials 121 is therefore 0. In this case, the quantity of radial modification ΔR is 0, so that the thermal coefficient of the moment of inertia is not modified.

[0091] When the adjustment part 100 is turned in the direction + from the reference position, the part made of two materials 121 is also deformed towards the external side in the first radial direction, so that the X component of the deformation vector of the two-material part 121 is produced (A2 and A3 in Fig. 13). By increasing the angle of rotation θ in the + direction, the positive X-component is gradually increased. That is, by setting the rotation angle θ of the adjustment part 100 in the + direction from the reference position, it is possible to increase the amount of increase in the moment of inertia of the pendulum. - hairspring 54 during a temperature increase. In addition, when the angle of rotation θ is 90 degrees (A3 in Fig. 13), the two-material part 121 is deformed only towards the outer side in the first radial direction. Therefore, in the case where the angle of rotation θ is 90 degrees, the positive X component is maximum and the Y component is zero. In this way, by turning the adjustment portion 100 in the + direction from the reference position, the thermal coefficient of the moment of inertia can be increased.

[0092] On the other hand, when the adjusting part 100 is rotated in one direction from the reference position, the part made of two materials is also deformed towards the inner side according to the first radial direction, whereby the The negative X-component of the strain vector of the two-material part 121 is produced (A4 and A5 in Fig. 13). By increasing the angle of rotation in one direction, the negative X-component increases. This means that, by situating the angle of rotation θ of the adjustment part 100 in one direction from the reference position, it is possible to suppress the increase in the moment of inertia of the sprung balance 54 during an increase in temperature. Furthermore, in the case where the angle of rotation θ is 90 degrees (A5 in FIG. 13), the part made of two materials 121 deforms only towards the inner side in the first radial direction. Therefore, in the case where the angle of rotation θ is 90 degrees, the negative X component is maximum and the Y component is zero. In this way, by turning the adjustment part 100 in the direction - from the reference position, the thermal coefficient of the moment of inertia can be reduced.

Fig. 14 is a graph showing the rotation between the rotation angle θ of the adjustment part 100 and the amount of radial change ΔR.

As shown in Fig. 14, from the results of Fig. 13 described above, when the adjustment portion 100 is rotated in the + direction from the reference position, the amount of radial change ΔR increases. in the + direction (towards the outer side in the first radial direction). On the other hand, when the adjusting part 100 is rotated in the - direction from the reference position, the amount of radial change ΔR of the adjusting part 100 increases in the - direction (towards the inner side along the first radial direction).

FIG. 15 is a graph showing the relationship between the temperature (°C) and the rate due to the difference in the thermal coefficient of the Young's modulus of balance spring 63. In FIG. 15, the broken line G1 corresponds to the case where the step (the oscillation cycle of the balance-spring 54) has a negative thermal characteristic, and the dashed line G2 corresponds to the case where the step has a positive thermal characteristic.

As G1 shows in FIG. 15, due to the relationship between the Young's modulus of hairspring 63 and the moment of inertia of balance-spring 54, when walking has a negative thermal characteristic, walking tends to be delayed when the temperature increases. In this case, the adjusting part 100 is rotated in the - direction from the reference position. This achieves a radial change amount ΔR toward the inner side in the first radial direction upon a temperature increase and reduces the coefficient of the moment of inertia, so that it is possible to suppress an increase in the moment of inertia of balance-spring 54 accompanying a temperature increase. As a result, an adjustment is made so that the thermal coefficient of the period of oscillation of the balance-spring 54 approaches 0, which makes it possible to maintain a constant rate, independent of changes in temperature (see the solid line G3 in figure 15).

On the other hand, as G2 shows in Figure 15, due to the relationship between the Young's modulus of the balance spring and the moment of inertia of the balance-spring 54, when the step has a thermal characteristic positive, the rate tends to advance when the temperature increases. In this case, the adjusting part 100 is rotated in the + direction from the reference position. This makes it possible to guarantee a radial change amount ΔR towards the outer side according to the first radial direction accompanying a temperature increase and to increase the coefficient of the moment of inertia, so that it is possible to increase the moment of inertia of balance-spring 54 accompanying a temperature increase. As a result, an adjustment is made so that the thermal coefficient of the period of oscillation of the balance-spring 54 approaches 0, which makes it possible to maintain a constant rate, independent of changes in temperature (see the solid line G3 in Figure 15).

[0098] In this way, the angle of rotation θ of the adjustment part 100 is modified as a function of the thermal characteristic of the step, whereby it is possible to correct the thermal coefficient of the moment of inertia of the balance- spiral 54 both plus and minus. As a result, it is easier to suppress variations affecting the thermal coefficient of the Young's modulus, thanks to the thermal characteristic of the moment of inertia of the balance-spring 54.

In the present embodiment described above, the part in two materials 121 is provided at a position having rotational symmetry, on the balance wheel 62.

[0100] With this constitution, the part in two materials 121 undergoes a deformation during a change in temperature, whereby the average diameter of the balance wheel 62 is modified. As a result, it is possible to correct the thermal characteristic of the moment of inertia.

[0101] In particular, in the present embodiment, the position of the adjustment part 100 around the second axis O2 can be adjusted. Therefore, it is possible to change the orientation of the two-material part 121 depending on the thermal coefficient of the Young's modulus of the hairspring 63. As a result, the amount of correction of the thermal coefficient of the two-material part 121 can be changed both plus and minus and the thermal coefficient of the moment of inertia of the sprung balance 54 can be corrected both plus and minus. This means that a variation affecting the thermal coefficient of the Young's modulus can easily be canceled thanks to the thermal characteristic of the moment of inertia of the balance-spring 54. As a result, it is possible to keep the period of oscillation of the sprung balance 54, which makes it possible to propose a better sprung balance 54 with regard to the thermocompensation capacity.

[0102] In addition, in the present embodiment, even if the orientation of the part in two materials 121 is modified, the length, in the direction of the second axis 02, of the adjustment part 100 is kept constant. Consequently, unlike the conventional case in which the effective length of the part in two materials 121 is modified, it is possible to eliminate the center of gravity of the balance-spring 54 shifting at the predetermined temperature T0. As a result, it is possible to suppress the generation of a balancing error and reduce the difference in behavior.

[0103] In the present embodiment, the adjustment part 100 is provided on the rim 73 of the balance wheel 62, so that it is possible to move the adjustment part 100 away from the first axis O1, in the first radial direction. As a result, it is possible to increase the radial change amount ΔR, thereby increasing the amount of thermal coefficient correction due to the two-material part 121.

In the present embodiment, the adjustment part 100 is arranged on the internal side in the first radial direction, with respect to the rim 73, and extends along the tangent to the rim 73.

[0105] In this constitution, it is possible to obtain the quantity of change ΔR accompanying a change in temperature, while avoiding an increase in the size of the balance-spring 54 resulting from the addition of the adjustment part 100.

[0106] In the present embodiment, the adjustment portion 100 has the flyweight 122 at the distal end, so that it is possible to increase the weight of the distal end, which is the with the greatest deformation of the adjusting part 100. Therefore, it is possible to increase the amount of correction of the thermal coefficient due to the two-material part 121.

[0107] In the present embodiment, the adjusting part 100 extends cantilevered, so that it is possible to obtain the amount of a radial change ΔR resulting from a change of temperature and increase the amount of thermal coefficient correction due to the bimaterial part 121.

[0108] In the present embodiment, the intervention hole 117 is formed in the serge 73, so that it is possible to couple a tool to the coupling portion of the fixing portion 120, by the intervention hole 117. Therefore, the position of the adjusting part 100 around the second axis O2 can be easily adjusted. In addition, the angle of rotation θ of the adjustment part 100 is changed via the fixing portion 120 so that, compared to the case where the angle of rotation θ of the adjustment part 100 is modified via the distal end (the two-material part 121 and the flyweight 122), it is possible to avoid plastic deformation of the adjustment part 100 during the angular adjustment of the adjustment part 100 Therefore, it is possible to prevent a variation affecting the running at the predetermined temperature T0 from being generated due to plastic deformation of the adjusting part 100.

In the present embodiment, balance spring 63 is made of a constant modulus material.

[0110] With this constitution, it is possible to reduce the change affecting the Young's modulus following a change in temperature in order to eliminate the period of oscillation being dependent on the temperature. Furthermore, in the present embodiment, it is possible to correct variations affecting the thermal coefficient of the Young's modulus, by a rotation angle θ of the adjustment part 100, so that the production and organization at the time of production of the hairspring 63 are facilitated. Thus, it is possible to obtain progress in the manufacturing efficiency of the hairspring 63 and to obtain a reduction in costs.

In the present embodiment, the center of gravity of the adjustment part 100 is on the second 02 so that, when the position of the adjustment part 100 around the second axis 02 is adjusted, it It is possible to prevent the center of gravity of the adjustment part 100 from being offset away from the second axis O2 due to the angle of rotation θ of the adjustment part 100. As a result, it It is possible to prevent the center of gravity of the balance-spring 54 from shifting as a function of the angle of rotation θ of the adjustment part 100, so that it is possible to reliably reduce a difference in behavior.

The movement 2 and the timepiece 1 of this embodiment are provided with the balance-spring 54 described above, so that it is possible to propose a movement 2 and a timepiece 1 having a high quality leading to low rate variations.

Second embodiment

A second embodiment of the present invention will now be described. FIG. 16 is a perspective view of a balance-spring 201 according to the second embodiment. This embodiment differs from the embodiment described above in that the support portion 202 extends along the direction of the first axis, from the rim 73. In the following description, the components which are the same that those of the embodiment described above are designated by the same reference numerals and description thereof will be omitted.

[0114] In the balance-spring 201 shown in Figure 16, the support portions 202 are formed in positions of the rim 73 which have rotational symmetry (which are rotationally invariant). The support portion 202 extends from the rim 73, rearwards in the direction of the first axis, and extends inwards in the first radial direction. In the part of the support portion 202 which extends inwards along the first radial direction relative to the rim 73, are formed mounting holes 205 extending through the support portion 202 along the direction of the second axis. The attachment portion 120 of the adjustment portion 100 is driven into a mounting hole 205.

[0115] In this way, in the present embodiment, the rim 73 and the adjustment part 100 are at different positions according to the direction of the first axis. Consequently, during a deformation, in the first radial direction, of the adjustment part 100 due to a change in temperature, it is possible to avoid interference between the serge 73 and the adjustment part 100 and it is possible to obtain the amount of radial change ΔR of the adjustment part 100.

The technical scope of the present invention is not limited to that of the embodiments described above, but allows various modifications without departing from the scope of the present invention.

[0117] For example, although in the embodiments described above, two adjustment portions 100 are provided at positions having rotational symmetry on the rim 73, this should not be interpreted restrictively. This means that, for example as shown in Fig. 17, three or more adjustment parts 100 can be provided as long as the adjustment parts 100 are provided at positions having rotational symmetry, i.e. - say a symmetry of any order (these positions are invariant under rotation).

[0118] While in the embodiments described above, the adjustment part 100 rotates around the second axis O2, provided that the outer peripheral surface of the fixing portion 120 slides on the inner peripheral surface of the hole. mounting 115, this should not be interpreted restrictively. This means that any other constitution will be suitable as long as the position of the adjustment part 100 can be adjusted around the second axis 02. In this case, for example as shown in FIG. 18, a male spline 120a formed on the fixing portion 120 can be engaged with a female spline 115a formed in the mounting hole 115. With this constitution, the orientation of the part in two materials 121 having been chosen, the fixing portion 120 is engaged in a manner adjusted in the mounting hole 115, whereby it is possible to adjust the position of the adjustment part 100 around the second axis 02.

[0119] After the angular adjustment of the adjustment part 100, the adjustment part 100 can be fixed to the support portion 110 so as to no longer be able to rotate. The technique for securing adjustment portion 100 may be welding, gluing, or the like, or it may be secured by means of separate fasteners (eg, set screw).

[0120] While in the embodiments described above, the attachment portion 120 is snugly engaged in the mounting hole 115, this should not be construed restrictively. The mounting technique of the adjustment part 100 allows modifications according to needs. For example, a protrusion formed on the serge 73 may snugly engage with a depression formed in the adjustment portion 100.

[0121] While, in the embodiments described above, the second axis 02 of the adjustment part 100 extends along a tangent to the serge 73, this should not be interpreted restrictively. This means that any other constitution will be suitable since the X-component of the deformation vector of the adjusting part 100 is produced due to the deformation of the two-material part 121 due to a change in temperature. In this case, the second axis O2 can, for example, be positioned in a direction crossing the direction of the first axis or in a direction parallel to the direction of the first axis.

[0122] Whereas, in the embodiments described above, the adjustment part 100 is carried by the rim 73, via the support portion 110, this should not be interpreted restrictively. This means that any other construction will be suitable as long as the adjustment part 100 is provided on the part (the main balance wheel body) of the balance-spring 54 rotated by the power of the balance spring 63. In this case , examples of balance wheel main bodies include balance shaft 61, balance wheel 62 (hub 71, spokes 72, etc.), and double chainring 67.

[0123] While, in the embodiments described above, the low expansion element 130 and the high expansion element 131 are formed as plates having the same shape, this should not be interpreted restrictively. For example, as shown in Figure 19, low expansion element 130 and high expansion element 131 may have different thicknesses. Furthermore, the sections of the low expansion element 130 and of the high expansion element 131 orthogonal to the second axis O2 have a shape which is not limited to the rectangular shape. This allows modifications as required and these sections can be triangular, semi-circular or the like.

[0124] While, in the embodiments described above, the low expansion element 130 and the high expansion element 131 are stacked together in the second radial direction, this should not be interpreted restrictively. Any other constitution will be suitable provided that the elements are stacked together in a direction crossing the direction of the second axis. In this case, as shown for example in Figure 19, the low expansion element 130 gradually widening towards the distal end and the high expansion element 131 gradually thinning towards the distal end. can be stacked together.

[0125] While in the embodiments described above the adjustment portion 100 extends linearly, this should not be construed restrictively. The adjustment part 100 can extend so as to cross the direction of the second axis or can be formed in a wave shape since it allows angular adjustment around the second axis 02.

[0126] While in the embodiments described above the adjustment portion 100 extends cantilevered, this should not be construed restrictively. It can also extend according to the shape of an eccentric.

[0127] While, in the embodiments described above, the part made of two materials 121 extends over the entire zone of the adjustment part 100 located between the support portion 110 and the flyweight 122, this does not should not be interpreted restrictively. Any other construction may be suitable as long as at least a part of the adjustment part 100 is made of the part in two materials 121.

Furthermore, without departing from the scope of the present invention, the components of the embodiments described above can be replaced by well-known components as needed. Furthermore, the modifications mentioned above can be combined with each other, as required.

Claims (12)

1. Balance for balance-spring of the thermocompensated type, comprising: a main balance body comprising a balance shaft (61) extending along a first axis (O1) and configured to be driven in an alternating rotational movement around the first axis (O1) by the power of a hairspring; and at least two adjustment parts (100) which extend from locations where they have rotational symmetry about the first axis (O1) of the balance main body, each adjustment part extending along a second axis (02) and allowing their angular adjustment around the corresponding second axis (02), each adjustment part comprising a part made of two materials (121) obtained by joining together, in a direction crossing the second axis (02), materials with different coefficients of expansion. 2. Balance for a balance-spring of the thermocompensated type according to claim 1, in which the main body of the balance comprises: the balance shaft (61); and a balance wheel (62) which includes a rim (73) surrounding the balance shaft (61) on the outer side in a radial direction orthogonal to the first axis (O1) and which is mounted on the balance shaft (61 ); and each adjustment portion (100) extends from the serge (73). 3. Balancer for a balance-spring of the thermocompensated type according to claim 2, in which each adjustment part (100) is arranged on the inner side of the rim (73) in a plan view obtained by looking from the direction of the first axis (O1), each adjustment part (100) extending along a direction tangential to the rim (73). 4. Balance for a balance-spring of the thermocompensated type according to claim 2 or 3, in which the part made of two materials (121) is offset from the rim (73) in the direction of the first axis (O1). 5. Balance for balance-spring of the thermocompensated type according to one of claims 1 to 4, wherein each adjustment part (100) comprises a flyweight (122). 6. Balance for balance-spring of the thermocompensated type according to one of claims 1 to 5, wherein at least two through holes (115; 205) extending through the main balance body in the direction of the second axis (02 ) are formed in the main body of the balance wheel; each adjustment part (100) comprises a fixing portion (120) which is located at one end, in the direction of the second axis (02), with respect to the part made of two materials (121) and which is engaged in such a way fitted into and engaged with one of the through holes (115); and a portion (135) for coupling a tool is formed in the end surface of the fixing portion (120) facing said end in the direction of the second axis (02). 7. Balance for balance-spring of the thermocompensated type according to one of claims 1 to 6, wherein each adjustment part (100) extends cantilevered along the second axis (O2). 8. Balance for balance-spring of the thermocompensated type according to one of claims 1 to 7, wherein the center of gravity of each adjustment part (100) is on the second axis (02) corresponding. 9. Balance-spring of the thermocompensated type, comprising a balance for balance-spring of the thermocompensated type according to one of claims 1 to 8, as well as a balance spring (63). 10. Balance-spring of the thermocompensated type according to claim 9, characterized in that the balance-spring is made of a material with a Young's modulus without fluctuation with changes in temperature. 11. Movement, comprising a balance for a balance-spring of the thermocompensated type according to one of claims 1 to 8 or a balance-spring of the thermocompensated type (54; 201) according to claim 9 or 10. 12. Timepiece, comprising a movement according to claim 11.