JP2015179014A - Barrel for spiral spring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a barrel capable of improving the utilization efficiency of the volumetric capacity for storing energy while reducing variation in the torque generated in the process when a spiral spring is released.SOLUTION: A spiral spring is constituted of a first spiral spring 1 and a second spiral spring 2 each of which has height dimension varying in a longitudinal direction, which are used being wound and overlapped with each other. The two spiral springs may be disposed so that the height of the overlapped spiral springs is constant. The position of the overlapping part of the two spiral springs in height direction of the spiral spring varies in order in a longitudinal direction. The barrel is arranged so that the inner/outer overlapping parts are prevented from overlapping or interfering with each other while preventing useless space from being generated in the spiral springs when the spiral springs are wound to thereby ensure the utilization efficiency of the space in the barrel 5. The width w in the overlapping part 3 gets smaller from the inner end toward the outer end to reduce the rigidity of the spiral spring toward the outer end. With this, uniform torque is obtained as time passes.

Description

  The present invention relates to a structure of a barrel having an improved mainspring serving as a power source for a mechanical timepiece or the like.

In a mechanical timepiece, a mainspring is generally used as a power source. A barrel having a normal mainspring will be described with reference to FIG.
FIG. 7 is a cross-sectional view schematically showing a conventional barrel, FIG. 7 (a) shows a state where the mainspring is unwound to some extent, and FIG. 7 (b) shows that the mainspring is wound. Shows the state.

  In FIG. 7, reference numeral 4 denotes a conventional mainspring, in which a long and narrow elastic member having a uniform rectangular cross section is wound in a coil shape, and the height of the cross section is h and the thickness is t. Reference numeral 5 denotes an incense box, which is a substantially cylindrical container that houses the wound mainspring 4. Reference numeral 5 a denotes an inner peripheral surface of the barrel 5. A barrel 6 is a true barrel, which serves as a winding shaft for the mainspring 4 and a rotation shaft for the barrel 5, and fixes or holds the inner end of the mainspring 4 to a fixing portion 6a on the outer periphery thereof.

  The outer end of the mainspring 4 is fixed to the inner peripheral surface 5a of the barrel 5 or is frictionally coupled to the inner peripheral surface 5a of the barrel 5 via a slipping attachment (not shown). The elastic force to unwind the mainspring 4 generates a torque that rotates the barrel 5 with respect to the barrel 6. A gear for transmitting the torque to the train wheel of the watch is usually provided on the outer periphery of the barrel 5, but this is also not shown.

Next, the torque generated by the conventional mainspring built in the conventional barrel is described.
FIG. 8 is a diagram for explaining a change in torque at which the mainspring in the barrel is generated. The figure shows a change in torque generated while the barrel is rotated from the fully wound state of the mainspring to the open state. The vertical axis represents torque, and the horizontal axis represents time change. A curve 8 is a torque curve when a conventional mainspring is used.

  The mainspring is tightened to the winding stem side in the full winding state, but the diameter increases as it unwinds, and is deformed so as to be in close contact with the inner peripheral surface 5a of the barrel in order from the outer end. The mainspring of the portion that is in close contact with the inner peripheral surface 5a no longer generates torque, and torque is generated from the mainspring in the inner portion. However, since the portion gradually becomes smaller in diameter, the arm length of the torque decreases, and the torque decreases with time as the mainspring is unwound.

  Generally, the barrel is required to rotate at a constant time for as long as possible. This is because the accuracy of the mechanical timepiece using the barrel is lowered unless the barrel is rotated at a constant rate. Therefore, it is preferable that the built-in mainspring generate a constant torque for as long as possible. However, as shown in FIG. 6, the torque variation of the conventional mainspring is considerably large.

  The torque T at which the mainspring is generated is obtained by the following formula 1.

T = (Eht ³ πN) / 6L (1)

Here, L is the mainspring length, h is the mainspring height (cross-sectional dimension in the direction parallel to the true axis of the barrel)
, T is the mainspring thickness, N is the effective number of turns, and E is the elastic modulus.

Generally, in the barrel, the following characteristics are required.
(A) The fluctuation of the generated torque should be small within the range of the effective rotation speed of the barrel that is set between the fully wound state and the open state.
(A) The time for which the predetermined torque is maintained is long.
(C) The use efficiency of the inner volume of the cylindrical barrel is good and a large amount of energy can be stored.
(D) The barrel is small.
The terms (a) to (d) are strongly related to each other and are often achieved with the same configuration.

  From the above viewpoint, various efforts have been made for improvement. For example, this is a technique in which a plurality of mainsprings are provided in one barrel (for example, refer to Patent Document 1). Moreover, it is the technique of not making the width | variety of the mainspring of an incense case uniform over the length of a mainspring (for example, refer patent document 2).

  In the prior art shown in Patent Document 1, by increasing the mainspring length L in Formula 1 as much as possible, a large amount of energy is accumulated, the duration is increased and the torque is substantially flattened. It was intended to spread.

  As a means for this, a configuration in which three mainsprings are connected in series by stacking flat spiral springs in three stages and connecting inner ends and outer ends of adjacent mainsprings.

  The prior art shown in Patent Document 2 intends to flatten the torque, and does not make the mainspring height h in Formula 1 above constant over the entire length, but widens the height on the inner end side (winding shaft side). The height is narrowed on the outer end side and changed into a taper shape.

  In the prior art disclosed in Patent Document 2, the portion that generates the torque of the mainspring moves toward the inner diameter side (that is, the mainspring having a larger height and higher rigidity) as it is unwound, while the height is narrower. Since the portion near the outer end with small rigidity is in close contact with the inner side surface of the barrel inner wall and does not operate, it seems that there is certainly an effect of compensating for the torque reduction even if it is unwound.

Japanese Examined Patent Publication No. 36-14655 (Pages 1 and 2, Fig. 2) Japanese Patent Laid-Open No. 53-13051 (pages 1 to 3, FIG. 2)

  The problem of the technique shown in Patent Document 1 is that the mainsprings are stacked in multiple stages above all, and if these are housed together with the discs for partitioning, the thickness of the barrel becomes thick, which reduces the size of equipment such as a watch to be mounted. It is disadvantageous. In particular, there is a strong demand for wristwatches, making it impossible to downsize the movement. In addition, the structure in the barrel is complicated, and there is a doubt whether stable operation can be obtained.

  In the conventional technique shown in Patent Document 2, the mainspring height h (b in the literature) is tapered, so that the space surrounding the spiral mainspring is like an abacus ball with a thin edge and a flat shape. Presents a unique shape.

As a result, when it is accommodated in the cylindrical space of the barrel, waste space is created above and below the abacus balls, and the volume in which energy can be stored (the volume occupied in the process of unwinding the mainspring, in this example the abacus ball shape) is reduced. However, there is a problem that the use efficiency of the volume is poor and the generated torque must be reduced as a whole.

  As described above, none of the conventional techniques is highly effective and satisfactory. The first object of the present invention is to reduce the fluctuation of the generated torque in the process of unwinding the mainspring. In addition, a second object is to provide a barrel with high volumetric efficiency for energy storage.

  The barrel of the present invention employs the following configuration in order to achieve the above object.

  In the barrel that houses the mainspring, one end of the barrel is fixed, wound around the barrel, and the other end is in contact with the inner wall of the barrel, the mainspring has a low mainspring height at one end, A first mainspring having a high mainspring height at the other end and a second mainspring having a high mainspring height at one end and a low mainspring height at the other end, and the first mainspring and the second mainspring. Is characterized in that they are joined with an overlapping portion partially overlapping in the height direction.

  By adopting such a configuration, the mainspring thickness can be substantially increased by the overlapping portion, and the generated torque can be increased.

  The overlapping portion may be displaced in the height direction from the true barrel side toward the inner wall side.

  By adopting such a configuration, it is possible to avoid further overlapping of the mainspring overlapping with the adjacent mainspring and the overlapping portion, to prevent the number of windings from decreasing, and to increase the efficiency of the mainspring.

  You may make it an overlapping part become small with respect to a height direction as it goes to an inner wall side from a barrel complete side.

  By adopting such a configuration, the partial rigidity in the length direction of the mainspring can be changed small from the inner end toward the outer end.

  The barrel complete has a first diameter portion having a large diameter and a second diameter portion having a small diameter. The first mainspring has one end fixed to the first diameter portion, and the second mainspring is The one end may be fixed to the second diameter portion.

  By adopting such a configuration, the thickness of the overlapping portion on the inner end side of the mainspring can be absorbed by the small-diameter step portion formed in the true barrel and the mainspring accommodation efficiency can be increased.

  The barrel of the present invention can improve the rigidity distribution of the mainspring and reduce the fluctuation of the generated torque. In addition, the space utilization efficiency of the mainspring can be improved and the stored energy can be increased.

It is sectional drawing explaining the barrel in Example 1 of this invention. It is the top view and side view explaining the mainspring which comprises the barrel of this invention. It is a figure which shows the torque curve which compares the barrel of this invention with the conventional barrel. It is a top view explaining the mainspring which comprises the barrel of the present invention. It is a top view explaining the mainspring which comprises the barrel of the present invention. It is sectional drawing explaining the barrel in Example 2 of this invention. It is sectional drawing explaining the conventional barrel. It is a figure which shows the torque curve of the conventional barrel.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are schematically shown for easy explanation, and portions not related to the explanation are omitted. The same number is assigned to the same configuration.

[Description of the barrel of Example 1: FIG. 1]
First, the element which comprises the barrel of Example 1 is demonstrated.
FIG. 1 is a diagram for explaining the barrel, and is a schematic sectional view represented by a section including the barrel true. FIG. 1A shows a state in which the mainspring is unwound. FIG.1 (b) has shown the state by which the mainspring was wound up substantially.

  In FIG. 1, 5 is a barrel, and its central axis is a barrel 6. The barrel 6 is provided with a fixing portion 6a having a slightly larger diameter for fixing the inner end portion of the mainspring, and a step portion 6b formed by a difference in shaft diameter between other portions.

  The mainspring built in the barrel 5 includes a first mainspring 1 having a predetermined thickness t1 and a second mainspring 2 having a predetermined thickness t2. These two mainsprings are partially overlapped in the mainspring height h direction, and are referred to as overlapping portions 3. The width of the overlapping portion 3 is a width w (a dimension in the direction of the height h of the mainspring).

  In the first mainspring 1, an inner end 1 a which is one end is fixed to a fixing portion 6 a of the barrel 6. In the example shown in FIG. 1, the outer end 1 b that is the other end is in contact with the inner peripheral surface 5 a of the barrel 5 by a slipping attachment (not shown) or the like.

  The second mainspring 2 is fixed to the first mainspring 1 that is fixed to the stepped portion 6b of the barrel complete 6 or the inner end 2a that is one end of the second mainspring 2 is fixed to the barrel fixed portion 6a. Indirectly fixed (substantially fixed) to the barrel 6. In the example shown in FIG. 1, the outer end 2 b that is the other end is in contact with the surface of the outer end 1 b of the first mainspring 1 on the barrel 6 side.

  The first mainspring 1 and the second mainspring 2 are partially overlapped by the overlapping portion 3, but in the inside of the barrel from the barrel true 6 side to the inner peripheral surface 5 a of the barrel, the first mainspring 1 and The height h of the mainspring formed of the second mainspring 2 is kept at a predetermined value. The height h of the mainspring can be freely determined by the performance required for the barrel 5.

  The width w of the overlapping portion 3 between the first mainspring 1 and the second mainspring 2 may be uniform for each turn formed by winding these two mainsprings around the barrel 6. However, the torque characteristic of the mainspring can be controlled by giving a change to the width w. This torque characteristic control will be described in detail later. In this embodiment, as shown in FIG. 1, the width w gradually decreases from the barrel 6 side to the inner peripheral surface 5a of the barrel. And the position of the overlapping part 3 also reaches the inner peripheral surface 5a of the barrel 5 from the barrel case 6 side, and is shifted in the height direction of the mainspring so that the overlapping parts 3 of the adjacent rounds do not overlap at the same position. Yes.

  In addition, in the overlapping part 3, it is desirable that at least a part of the contact surfaces of the mainsprings is joined by welding, adhesion, or the like, and the operation will be described below for the purpose, but the overlapping surfaces are only in frictional contact. Even so, a certain degree of effect is exhibited.

  In FIG. 1, a gear to be provided on the outer periphery of the barrel 5, a winding mechanism such as a square wheel to be coupled to the barrel 6, and a detailed shape for fixing the inner end of the mainspring and the barrel 6. Etc. are not shown.

[Description of mainspring: Fig. 2]
Next, the mainspring built in the barrel 5 will be described in detail.
FIG. 2 is a plan view and a side view for explaining the mainspring used in the barrel of the first embodiment.
FIG. 2A is a plan view showing a state in which the mainspring made up of the first mainspring 1 and the second mainspring 2 is taken out from the barrel 5 and completely unwound and stretched (or a state before being wound into the true barrel). FIG. FIG. 2B is a plan view showing a state in which the two mainsprings shown in FIG. 2C is a side view seen from the direction of arrow A in FIG. 2B, and FIG. 2D is a side view seen from the direction of arrow B in FIG. 2B.

  The first mainspring 1 and the second mainspring 2 housed in the barrel 5 as shown in FIG. 2 (a) are both elongated with a bottom in the longitudinal direction when viewed from the height direction. It has a rough shape that becomes a trapezoid.

  The first mainspring 1 shows a state in which the base 1f of the trapezoid is on the lower side of the drawing and the hypotenuse 1s is on the upper side of the drawing. The second mainspring 2 shows the trapezoidal base 2f on the upper side of the drawing and the hypotenuse 2s on the lower side of the drawing.

  As shown in FIG. 2 (b), in this example, the first mainspring 1 is placed in front of the drawing so that both the mainsprings have a predetermined width w of the overlapping portion 3 (the dimension in the direction of the height h of the mainspring). It is piled up to become. The height h of the mainspring made up of the first mainspring 1 and the second mainspring 2 is kept constant at a predetermined value.

  The width w of the overlapping portion 3 is not constant and changes over the longitudinal direction of the mainspring. That is, as shown in FIG. 2C, the width w increases toward the inner end direction of the mainspring (the direction of the inner end portions 1a and 2a), and as shown in FIG. It becomes smaller toward the ends 1b and 2b. The shapes of the first mainspring 1 and the second mainspring 2 are determined so as to be like this (the width w of the overlapping portion 3 is determined).

If it does in this way, the rigidity of the arbitrary parts in the mainspring which consists of the 1st mainspring 1 and the 2nd mainspring 2 can be adjusted.
That is, the larger the width w of the overlapping portion 3 of the mainspring is, the equivalent thickness tv () of the cross section of the mainspring when the first mainspring 1 and the second mainspring 2 are considered as the mainspring. In other words, the thickness t1 of the first mainspring 1 and the thickness t2 of the second mainspring 2 overlap each other, and the second moment of the cross section increases.

  In the configuration in which the first mainspring 1 and the second mainspring 2 are overlapped, as shown in FIG. 2 (c), in the portion close to the inner ends 1a, 2a of the barrel 5 of the barrel 5 The width of the overlapping portion 3 is defined as the width wa, the equivalent thickness thereof is defined as tva (not shown), and the outer end portions 1b and 2b on the inner peripheral surface 5a side of the barrel 5 as shown in FIG. Assuming that the width of the overlapping portion 3 in the portion close to is the width wb and the equivalent thickness is tvb (not shown), wa> wb and tva> tvb.

  As a result, the partial rigidity of the mainspring made up of the first mainspring 1 and the second mainspring 2 increases as it approaches the barrel complete 6, and decreases as it approaches the inner peripheral surface 5a of the barrel 5. .

As explained in the prior art shown in Patent Document 2, as the mainspring is unwound,
In the portion that generates torque, the torque that is closer to the barrel 6 tends to be smaller. In the present invention, since the width wa of the overlapping portion 3 on the side close to the barrel 6 is increased (the equivalent thickness ta is increased) and the rigidity can be increased, the torque of the loose mainspring is compensated. In addition, it is possible to perform control such that the torque characteristics of the mainspring can be flattened.

  Further, as shown in FIGS. 1 and 2B, the position of the overlapping portion 3 in the mainspring composed of the first mainspring 1 and the second mainspring 2 is high within the range of the mainspring height h. It is shifted in the direction of h. In the present embodiment, the overlapping portion 3 has a low position in the portion close to the inner end 1a, 2a on the barrel 6 side of the barrel 5 and is close to the outer end 1b, 2b on the inner peripheral surface 5a side of the barrel 5. It will be high. That is, the mainspring overlapping portion 3 wound around the barrel 6 has a spiral shape.

  With such a configuration, even when the mainspring made up of the first mainspring 1 and the second mainspring 2 is wound around the barrel complete 6 as shown in FIG. 3 and the overlapping portion 3 that circulates adjacently can be avoided (the first mainspring 1 and the second mainspring 2 may interfere with each other in the overlapping portion 3).

  By doing so, the mainspring does not become thick in the direction of the inner peripheral surface 5a of the barrel 5, and it is possible to prevent the number of turns from decreasing. That is, the efficiency of housing the mainspring can be increased, and the energy stored in the barrel 5 can be increased.

As described above, in the barrel 5 described above, even if the first mainspring 1 and the second mainspring 2 are tightened, the steps produced by the mainsprings are almost overlapped with each other to reduce a useless space generated in the spiral space. be able to.
As a result, the torque characteristic can be flattened, and the energy that can be stored can be increased.

[Comparison of torque characteristics: Fig. 3]
As a result of these, the torque characteristics of the barrel 5 of the present invention are compared with the torque characteristics of a conventional barrel.
FIG. 3 is a diagram comparing both torque characteristics on the assumption that the size of the barrel is equal to the number of windings of the mainspring wound in the barrel, and the mainspring comprising the first mainspring 1 and the second mainspring 2 is compared. The change in torque generated while the barrel 5 is rotated until the barrel 5 is unwound and released from the entire winding (tightening) state. A curve 7 shown in FIG. 3 is a torque characteristic of the barrel 5 of the present invention, and a curve 8 is a torque characteristic of the conventional barrel shown in FIG.

  As shown in FIG. 3, comparing the torque characteristic 7 of the barrel 5 of the present invention with the torque curve 8 of the conventional barrel, it can be seen that the barrel 5 of the present invention flattens the generated torque. By flattening the torque generated by the barrel, a stable torque can be generated for a long period of time while the barrel is rotating, and the accuracy of the mechanical timepiece using the barrel is stabilized.

  By the way, as shown in FIG. 3, the barrel of the present invention has a reduced maximum torque compared to the conventional barrel. This is because, as described above, the size of the barrel is the same and the number of windings of the mainspring built in the barrel is the same as that of the conventional barrel. That is, the thickness of each of the first mainspring 1 and the second mainspring 2 is thinner than the thickness of the mainspring built in the conventional barrel (see Formula 1).

  As is known, the maximum torque generated by the barrel can be determined by the connected gear train mechanism. Therefore, the barrel gear of the present invention shown in FIG. Therefore, there is no problem if a suitable torque calculation is performed.

[Description of Modification: FIG. 4]
In the barrel 5 of the first embodiment already described, the width w of the overlapping portion 3 of the mainspring composed of the first mainspring 1 and the second mainspring 2 is determined from the inner end direction (the direction of the inner end portions 1a and 2a). Until the outer end direction (the direction of the outer end portions 1b and 2b), it gradually changes linearly. Of course, the mainspring used in the barrel 5 of the present invention is not limited thereto.

  FIG. 4 is a diagram for explaining a modification of the mainspring, and is a plan view for explaining a state in which the first mainspring 1 and the second mainspring 2 are overlapped. In the example shown in FIG. 4, the width of the overlapping portion 3 is the same as the example shown in FIG. 2 described above, but the hypotenuses 1s and 2s of both mainsprings are curved. It has become.

[Explanation about the inner diameter of the mainspring or the true shape of the barrel: FIG. 5]
The shape of the first mainspring 1 and the second mainspring 2 constituting the mainspring used in the barrel of the present invention is that the shape of the hypotenuses 1s and 2s is particularly important. It can also be understood in view of what must be done.

  When winding the first mainspring 1 and the second mainspring 2 around the barrel 6, there is a gap in the mainspring wound so that the overlapping portions 3 are further overlapped so that the mainsprings do not interfere after one round. In order to avoid impairing space efficiency, the inner diameter of the mainspring or the diameter of the barrel 6 may inevitably be determined.

  FIG. 5 is a plan view showing the first mainspring 1 and the second mainspring 2 that are overlapped at the overlapping portion 3. As in the example already described, the first mainspring 1 is in front of the drawing.

  When winding the barrel 6, as shown in FIG. 5, the hypotenuse 1 s of the first mainspring 1 that is inside the first round and the hypotenuse 2 s of the second mainspring 2 that is inside the second round are as follows. It is desirable not to overlap.

  When the minimum winding diameter wound around the barrel 6 (that is, the diameter of the barrel 6 can be considered) is d, a distance s1 obtained by s1 = πd is obtained. Since the position 10 at the end of the hypotenuse 1s is a portion connected to the barrel 6 not shown in FIG. 5, when a virtual line J parallel to the bases 1f and 2f is drawn from this position 10 by a distance s1, The thickness and shape of the first mainspring 1 and the second mainspring 2 (particularly the hypotenuse 1s, so that the position 20 which is the intersection of the virtual line J and the hypotenuse 2s of the second mainspring 2 is higher than the position 10). 2s) is determined.

  This prevents the first mainspring 1 and the second mainspring 2 that have made one turn from overlapping (interfering) in the thickness direction after the first winding of the mainspring from the minimum diameter when the mainspring is tightened. It becomes the condition for. In the first embodiment, if the slope between the hypotenuse 1s of the first mainspring 1 and the hypotenuse 2s of the second mainspring 2 is loose, the distance s1, and therefore the minimum winding diameter d, tends to be relatively large.

  Therefore, when it is desired to reduce the minimum winding diameter d, i.e., to use the barrel 6 having a small diameter, the mainspring constituted by the first mainspring 1 and the second mainspring 2 has a shape that can reduce the distance s1. For example, the first mainspring 1 and the second mainspring 2 having the shape shown in FIG. 4 may be used.

[Explanation of the barrel of Example 2: FIG. 6]
Next, the barrel of Example 2 will be described.

  FIG. 6 is a view for explaining the barrel of the second embodiment, and is a schematic sectional view represented by a section including the barrel barrel true. This figure shows a state in which the mainspring is almost tightened.

  The barrel 50 shown in FIG. 6 is an example in which a barrel 60 having no step on the surface is used. The first mainspring 1 and the second mainspring 2 in which the overlapping portion 3 is overlapped with a width w are a barrel 60 that does not have a portion corresponding to the fixing portion 6a of the barrel 6 of the barrel 5 of the first embodiment shown in FIG. Fixed and wound.

  Although the barrel 50 according to the present invention can be constructed using such a barrel 60, the mainspring must be fixed to the barrel 6 at one end, so the inner end 1a of the first mainspring 1 and the barrel 60 A space 65 is created between the two.

  The space 65 is a dead space inside the barrel 50, but can wind the mainspring constituted by the first mainspring 1 and the second mainspring 2 described above, and the barrel 5 described above. The same effect can be achieved.

  When the first mainspring 1 and the second mainspring 2 are wound around the barrel full 60, there is no fixed portion 6a and stepped portion 6b of the barrel main stem 6 shown in FIG. It is desirable to take care not to overlap.

  Therefore, the mainspring having the shape shown in FIG. 4 may be used for the barrel 50 of the second embodiment. Since the hypotenuse 1s of the first mainspring 1 and the hypotenuse 2s of the second mainspring 2 are steeply inclined near the inner end, the minimum winding diameter d of the mainspring can be made smaller than that of the first embodiment, as described above. This is because there is less risk of interference between the first mainspring 1 and the second mainspring 2.

  In the embodiment of the present invention, the generation of interference and dead space is allowed up to, for example, several turns on the inner end side of the mainspring, but there is a possibility of avoiding interference and exhibiting space efficiency outside it.

  As described above, the barrel of the present invention flattens the generated torque without reducing the elastic energy that can be used by changing the partial rigidity and improving the efficiency of use of the volume by overlapping the first mainspring and the second mainspring. can do. Therefore, in a mechanical timepiece, the driving force of the escapement can be stabilized to improve isochronism and a sufficient duration can be obtained, and excellent effects can be obtained even when the present invention is applied to other devices. Is obtained.

  The present invention is suitable for a mechanical timepiece that requires a stable torque during the operation time.

DESCRIPTION OF SYMBOLS 1 1st mainspring 1a Inner end part of 1st mainspring 1b Outer end part of 1st mainspring 2 2nd mainspring 2a Inner end part of 2nd mainspring 2b Outer end part of 2nd mainspring 3 Overlapping of mainspring Part 5, 50 Incense box 6, 60 Incense box true 6a Incense box true fixing part 6b Incense box true stepped part 7 Torque curve of embodiment of the present invention 8 Torque curve of conventional example h mainspring height t mainspring thickness w mainspring overlap part Width of

Claims (4)

In the barrel that houses the mainspring, the one end is fixed to the barrel and is wound around the barrel, and the other end is in contact with the inner wall of the barrel,
The mainspring is a first mainspring having a low mainspring height at the one end and a high mainspring height at the other end, and a second mainspring having a high mainspring height at the one end and a low mainspring height at the other end. The mainspring and
The barrel according to claim 1, wherein the first mainspring and the second mainspring are coupled to each other with an overlapping portion partially overlapping in a height direction. The barrel according to claim 1, wherein the overlapping portion is displaced in the height direction from the true side of the barrel to the inner wall side. 3. The barrel according to claim 1, wherein the overlapping portion becomes smaller with respect to the height direction from the true side of the barrel to the inner wall side. The barrel complete has a first diameter portion having a large diameter and a second diameter portion having a small diameter,
The first mainspring has the one end fixed to the first diameter portion,
The barrel according to any one of claims 1 to 3, wherein the second mainspring fixes the one end to the second diameter portion.

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